ATtiny212/214/412/414/416
tinyAVR® 1-series
Introduction
The ATtiny212/214/412/414/416 are members of the tinyAVR®1-series of microcontrollers, using the AVR® processor
with hardware multiplier, running at up to 20 MHz, with 2/4 KB Flash, 128/256 bytes of SRAM, and 64/128 bytes of
EEPROM in a 8-, 14-, and 20-pin package. The tinyAVR®1-series uses the latest technologies with a flexible, lowpower architecture, including Event System, accurate analog features, and Core Independent Peripherals (CIPs).
Attention: Automotive products are documented in separate data sheets.
Features
•
•
•
CPU
– AVR® CPU
– Running at up to 20 MHz
– Single-cycle I/O access
– Two-level interrupt controller
– Two-cycle hardware multiplier
Memories
– 2/4 KB In-system self-programmable Flash memory
– 64/128 bytes EEPROM
– 128/256 bytes SRAM
– Write/erase endurance:
• Flash 10,000 cycles
• EEPROM 100,000 cycles
– Data retention:
• 40 years at 55°C
System
– Power-on Reset (POR)
– Brown-out Detector (BOD)
– Clock options:
• 16/20 MHz low-power internal RC oscillator
• 32.768 kHz Ultra Low-Power (ULP) internal RC oscillator
• 32.768 kHz external crystal oscillator
• External clock input
– Single-Pin Unified Program and Debug Interface (UPDI)
– Three sleep modes:
• Idle with all peripherals running for immediate wake-up
• Standby
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ATtiny212/214/412/414/416
•
•
•
•
– Configurable operation of selected peripherals
• Power-Down with full data retention
Peripherals
– One 16-bit Timer/Counter type A (TCA) with a dedicated period register and three compare channels
– One 16-bit Timer/Counter type B (TCB) with input capture
– One 12-bit Timer/Counter type D (TCD) optimized for control applications
– One 16-bit Real-Time Counter (RTC) running from an external crystal, external clock, or internal RC
oscillator
– Watchdog Timer (WDT) with Window mode, with a separate on-chip oscillator
– One USART with fractional baud rate generator, auto-baud, and start-of-frame detection
– One host/client Serial Peripheral Interface (SPI)
– One Two-Wire Interface (TWI) with dual address match
• Philips I2C compatible
• Standard mode (Sm, 100 kHz)
• Fast mode (Fm, 400 kHz)
• Fast mode plus (Fm+, 1 MHz)
– Analog Comparator (AC) with a low propagation delay
– 10-bit 115 ksps Analog-to-Digital Converter (ADC)
– 8-bit Digital-to-Analog Converter (DAC) with one external channel
– Multiple voltage references (VREF):
• 0.55V
• 1.1V
• 1.5V
• 2.5V
• 4.3V
– Event System (EVSYS) for CPU independent and predictable inter-peripheral signaling
– Configurable Custom Logic (CCL) with two programmable look-up tables
– Automated CRC memory scan
– External interrupt on all general purpose pins
I/O and Packages:
– Up to 18 programmable I/O lines
– 8-pin SOIC150
– 14-pin SOIC150
– 20-pin SOIC300
– 20-pin VQFN 3x3 mm
Temperature Ranges:
– -40°C to 105°C
– -40°C to 125°C
Speed Grades:
– 0-5 MHz @ 1.8V – 5.5V
– 0-10 MHz @ 2.7V – 5.5V
– 0-20 MHz @ 4.5V – 5.5V
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ATtiny212/214/412/414/416
Table of Contents
Introduction.....................................................................................................................................................1
Features......................................................................................................................................................... 1
1.
Silicon Errata and Data Sheet Clarification Document..........................................................................10
2.
tinyAVR® 1-series Overview..................................................................................................................11
2.1.
Configuration Summary..............................................................................................................11
3.
Block Diagram.......................................................................................................................................13
4.
Pinout.................................................................................................................................................... 14
4.1.
4.2.
4.3.
4.4.
5.
I/O Multiplexing and Considerations..................................................................................................... 18
5.1.
6.
Peripheral Address Map.............................................................................................................45
Interrupt Vector Mapping............................................................................................................ 46
System Configuration (SYSCFG)...............................................................................................47
AVR® CPU............................................................................................................................................ 50
8.1.
8.2.
8.3.
8.4.
8.5.
8.6.
8.7.
9.
Overview.................................................................................................................................... 20
Memory Map.............................................................................................................................. 21
In-System Reprogrammable Flash Program Memory................................................................21
SRAM Data Memory.................................................................................................................. 22
EEPROM Data Memory............................................................................................................. 22
User Row....................................................................................................................................22
Signature Bytes.......................................................................................................................... 22
I/O Memory.................................................................................................................................23
Memory Section Access from CPU and UPDI on Locked Device..............................................25
Configuration and User Fuses (FUSE).......................................................................................26
Peripherals and Architecture.................................................................................................................45
7.1.
7.2.
7.3.
8.
Multiplexed Signals.................................................................................................................... 18
Memories.............................................................................................................................................. 20
6.1.
6.2.
6.3.
6.4.
6.5.
6.6.
6.7.
6.8.
6.9.
6.10.
7.
8-Pin SOIC................................................................................................................................. 14
14-Pin SOIC............................................................................................................................... 15
20-Pin SOIC............................................................................................................................... 16
20-Pin VQFN.............................................................................................................................. 17
Features..................................................................................................................................... 50
Overview.................................................................................................................................... 50
Architecture................................................................................................................................ 50
Arithmetic Logic Unit (ALU)........................................................................................................ 52
Functional Description................................................................................................................52
Register Summary......................................................................................................................58
Register Description................................................................................................................... 58
NVMCTRL - Nonvolatile Memory Controller......................................................................................... 62
9.1.
Features..................................................................................................................................... 62
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9.2.
9.3.
9.4.
9.5.
Overview.................................................................................................................................... 62
Functional Description................................................................................................................63
Register Summary......................................................................................................................69
Register Description................................................................................................................... 69
10. CLKCTRL - Clock Controller................................................................................................................. 77
10.1.
10.2.
10.3.
10.4.
10.5.
Features..................................................................................................................................... 77
Overview.................................................................................................................................... 77
Functional Description................................................................................................................79
Register Summary......................................................................................................................83
Register Description................................................................................................................... 83
11. SLPCTRL - Sleep Controller................................................................................................................. 93
11.1.
11.2.
11.3.
11.4.
11.5.
Features..................................................................................................................................... 93
Overview.................................................................................................................................... 93
Functional Description................................................................................................................93
Register Summary......................................................................................................................97
Register Description................................................................................................................... 97
12. RSTCTRL - Reset Controller................................................................................................................ 99
12.1.
12.2.
12.3.
12.4.
12.5.
Features..................................................................................................................................... 99
Overview.................................................................................................................................... 99
Functional Description..............................................................................................................100
Register Summary....................................................................................................................104
Register Description................................................................................................................. 104
13. CPUINT - CPU Interrupt Controller..................................................................................................... 107
13.1.
13.2.
13.3.
13.4.
13.5.
Features................................................................................................................................... 107
Overview.................................................................................................................................. 107
Functional Description..............................................................................................................108
Register Summary ...................................................................................................................113
Register Description................................................................................................................. 113
14. EVSYS - Event System....................................................................................................................... 118
14.1.
14.2.
14.3.
14.4.
14.5.
Features................................................................................................................................... 118
Overview...................................................................................................................................118
Functional Description..............................................................................................................120
Register Summary....................................................................................................................122
Register Description................................................................................................................. 122
15. PORTMUX - Port Multiplexer.............................................................................................................. 129
15.1. Overview.................................................................................................................................. 129
15.2. Register Summary....................................................................................................................130
15.3. Register Description................................................................................................................. 130
16. PORT - I/O Pin Configuration..............................................................................................................135
16.1. Features................................................................................................................................... 135
16.2. Overview.................................................................................................................................. 135
16.3. Functional Description..............................................................................................................137
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16.4.
16.5.
16.6.
16.7.
Register Summary - PORTx.....................................................................................................140
Register Description - PORTx.................................................................................................. 140
Register Summary - VPORTx.................................................................................................. 152
Register Description - VPORTx................................................................................................152
17. BOD - Brown-out Detector.................................................................................................................. 157
17.1.
17.2.
17.3.
17.4.
17.5.
Features................................................................................................................................... 157
Overview.................................................................................................................................. 157
Functional Description..............................................................................................................158
Register Summary....................................................................................................................160
Register Description................................................................................................................. 160
18. VREF - Voltage Reference..................................................................................................................167
18.1.
18.2.
18.3.
18.4.
18.5.
Features................................................................................................................................... 167
Overview.................................................................................................................................. 167
Functional Description..............................................................................................................167
Register Summary ...................................................................................................................168
Register Description................................................................................................................. 168
19. WDT - Watchdog Timer.......................................................................................................................171
19.1.
19.2.
19.3.
19.4.
19.5.
Features................................................................................................................................... 171
Overview.................................................................................................................................. 171
Functional Description..............................................................................................................172
Register Summary - WDT........................................................................................................ 175
Register Description................................................................................................................. 175
20. TCA - 16-bit Timer/Counter Type A.....................................................................................................178
20.1.
20.2.
20.3.
20.4.
20.5.
20.6.
20.7.
Features................................................................................................................................... 178
Overview.................................................................................................................................. 178
Functional Description..............................................................................................................180
Register Summary - Normal Mode...........................................................................................190
Register Description - Normal Mode........................................................................................ 190
Register Summary - Split Mode............................................................................................... 209
Register Description - Split Mode.............................................................................................209
21. TCB - 16-Bit Timer/Counter Type B.................................................................................................... 225
21.1.
21.2.
21.3.
21.4.
21.5.
Features................................................................................................................................... 225
Overview.................................................................................................................................. 225
Functional Description..............................................................................................................227
Register Summary....................................................................................................................235
Register Description................................................................................................................. 235
22. TCD - 12-Bit Timer/Counter Type D.................................................................................................... 246
22.1.
22.2.
22.3.
22.4.
22.5.
Features................................................................................................................................... 246
Overview.................................................................................................................................. 246
Functional Description..............................................................................................................248
Register Summary....................................................................................................................271
Register Description................................................................................................................. 271
23. RTC - Real-Time Counter................................................................................................................... 296
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ATtiny212/214/412/414/416
23.1. Features................................................................................................................................... 296
23.2. Overview.................................................................................................................................. 296
23.3. Clocks.......................................................................................................................................297
23.4. RTC Functional Description..................................................................................................... 297
23.5. PIT Functional Description....................................................................................................... 298
23.6. Events...................................................................................................................................... 299
23.7. Interrupts.................................................................................................................................. 300
23.8. Sleep Mode Operation............................................................................................................. 301
23.9. Synchronization........................................................................................................................301
23.10. Debug Operation......................................................................................................................301
23.11. Register Summary....................................................................................................................302
23.12. Register Description.................................................................................................................302
24. USART - Universal Synchronous and Asynchronous Receiver and Transmitter................................318
24.1.
24.2.
24.3.
24.4.
24.5.
Features................................................................................................................................... 318
Overview.................................................................................................................................. 318
Functional Description..............................................................................................................319
Register Summary....................................................................................................................334
Register Description................................................................................................................. 334
25. SPI - Serial Peripheral Interface..........................................................................................................351
25.1.
25.2.
25.3.
25.4.
25.5.
Features................................................................................................................................... 351
Overview.................................................................................................................................. 351
Functional Description..............................................................................................................352
Register Summary....................................................................................................................359
Register Description................................................................................................................. 359
26. TWI - Two-Wire Interface.................................................................................................................... 366
26.1.
26.2.
26.3.
26.4.
26.5.
Features................................................................................................................................... 366
Overview.................................................................................................................................. 366
Functional Description..............................................................................................................367
Register Summary....................................................................................................................378
Register Description................................................................................................................. 378
27. CRCSCAN - Cyclic Redundancy Check Memory Scan...................................................................... 395
27.1.
27.2.
27.3.
27.4.
27.5.
Features................................................................................................................................... 395
Overview.................................................................................................................................. 395
Functional Description..............................................................................................................396
Register Summary - CRCSCAN...............................................................................................399
Register Description................................................................................................................. 399
28. CCL - Configurable Custom Logic...................................................................................................... 403
28.1.
28.2.
28.3.
28.4.
28.5.
Features................................................................................................................................... 403
Overview.................................................................................................................................. 403
Functional Description..............................................................................................................405
Register Summary....................................................................................................................412
Register Description................................................................................................................. 412
29. AC - Analog Comparator.....................................................................................................................419
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29.1.
29.2.
29.3.
29.4.
29.5.
Features................................................................................................................................... 419
Overview.................................................................................................................................. 419
Functional Description..............................................................................................................421
Register Summary....................................................................................................................423
Register Description................................................................................................................. 423
30. ADC - Analog-to-Digital Converter...................................................................................................... 428
30.1.
30.2.
30.3.
30.4.
30.5.
Features................................................................................................................................... 428
Overview.................................................................................................................................. 428
Functional Description..............................................................................................................429
Register Summary - ADCn.......................................................................................................436
Register Description................................................................................................................. 436
31. DAC - Digital-to-Analog Converter...................................................................................................... 454
31.1.
31.2.
31.3.
31.4.
31.5.
Features................................................................................................................................... 454
Overview.................................................................................................................................. 454
Functional Description..............................................................................................................455
Register Summary....................................................................................................................457
Register Description................................................................................................................. 457
32. UPDI - Unified Program and Debug Interface.....................................................................................460
32.1.
32.2.
32.3.
32.4.
32.5.
Features................................................................................................................................... 460
Overview.................................................................................................................................. 460
Functional Description..............................................................................................................462
Register Summary....................................................................................................................482
Register Description................................................................................................................. 482
33. Instruction Set Summary.....................................................................................................................493
34. Conventions........................................................................................................................................ 494
34.1.
34.2.
34.3.
34.4.
34.5.
Numerical Notation...................................................................................................................494
Memory Size and Type.............................................................................................................494
Frequency and Time.................................................................................................................494
Registers and Bits.................................................................................................................... 495
ADC Parameter Definitions...................................................................................................... 496
35. Electrical Characteristics.....................................................................................................................499
35.1. Disclaimer.................................................................................................................................499
35.2. Absolute Maximum Ratings .....................................................................................................499
35.3. General Operating Ratings ......................................................................................................500
35.4. Power Consumption................................................................................................................. 501
35.5. Wake-Up Time..........................................................................................................................503
35.6. Peripherals Power Consumption..............................................................................................503
35.7. BOD and POR Characteristics................................................................................................. 504
35.8. External Reset Characteristics................................................................................................. 505
35.9. Oscillators and Clocks..............................................................................................................505
35.10. I/O Pin Characteristics............................................................................................................. 507
35.11. TCD.......................................................................................................................................... 508
35.12. USART..................................................................................................................................... 508
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35.13.
35.14.
35.15.
35.16.
35.17.
35.18.
35.19.
35.20.
35.21.
SPI........................................................................................................................................... 509
TWI...........................................................................................................................................510
VREF........................................................................................................................................513
ADC..........................................................................................................................................514
TEMPSENSE........................................................................................................................... 516
DAC..........................................................................................................................................517
AC............................................................................................................................................ 518
UPDI Timing.............................................................................................................................518
Programming Time...................................................................................................................519
36. Typical Characteristics........................................................................................................................ 521
36.1. Power Consumption................................................................................................................. 521
36.2. GPIO........................................................................................................................................ 528
36.3. VREF Characteristics............................................................................................................... 536
36.4. BOD Characteristics.................................................................................................................538
36.5. ADC Characteristics................................................................................................................. 541
36.6. TEMPSENSE Characteristics.................................................................................................. 546
36.7. AC Characteristics....................................................................................................................546
36.8. OSC20M Characteristics..........................................................................................................550
36.9. OSCULP32K Characteristics................................................................................................... 552
36.10. TWI SDA Hold Timing ............................................................................................................. 553
37. Ordering Information........................................................................................................................... 554
37.1. Product Information.................................................................................................................. 554
37.2. Product Identification System...................................................................................................554
38. Package Drawings.............................................................................................................................. 556
38.1.
38.2.
38.3.
38.4.
38.5.
38.6.
Online Package Drawings........................................................................................................ 556
8-Pin SOIC............................................................................................................................... 557
14-Pin SOIC............................................................................................................................. 560
20-Pin SOIC............................................................................................................................. 563
20-Pin VQFN............................................................................................................................ 566
Thermal Considerations........................................................................................................... 569
39. Errata.................................................................................................................................................. 570
39.1. Errata - ATtiny212/214/412/414/416........................................................................................ 570
40. Data Sheet Revision History............................................................................................................... 571
40.1. Rev. A - 12/2020.......................................................................................................................571
40.2. Appendix - Obsolete Revision History......................................................................................577
The Microchip Website...............................................................................................................................582
Product Change Notification Service..........................................................................................................582
Customer Support...................................................................................................................................... 582
Product Identification System.....................................................................................................................583
Microchip Devices Code Protection Feature.............................................................................................. 583
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ATtiny212/214/412/414/416
Legal Notice............................................................................................................................................... 583
Trademarks................................................................................................................................................ 584
Quality Management System..................................................................................................................... 584
Worldwide Sales and Service.....................................................................................................................585
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ATtiny212/214/412/414/416
Silicon Errata and Data Sheet Clarification ...
1.
Silicon Errata and Data Sheet Clarification Document
Microchip aims to provide its customers with the best documentation possible to ensure the successful use of
Microchip products. Between data sheet updates, a Silicon errata and data sheet clarification document will contain
the most recent information for the data sheet. The ATtiny212/214/412/414/416 Silicon Errata and Data Sheet
Clarification(www.microchip.com/DS80000933) is available at the device product page on www.microchip.com.
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ATtiny212/214/412/414/416
tinyAVR® 1-series Overview
2.
tinyAVR® 1-series Overview
The following figure shows the tinyAVR 1-series devices, laying out pin count variants and memory sizes:
•
•
Vertical migration upwards is possible without code modification, as these devices are pin-compatible and
provide the same or more features. Downward migration may require code modification due to fewer available
instances of some peripherals.
Horizontal migration to the left reduces the pin count and, therefore, the available features
Figure 2-1. tinyAVR® 1-series Overview
Devices described in this data sheet
Devices described in other data sheets
Flash
32 KB
ATtiny3216
ATtiny3217
16 KB
ATtiny1614
ATtiny1616
ATtiny1617
8 KB
ATtiny814
ATtiny816
ATtiny817
ATtiny416
ATtiny417
20
24
4 KB
ATtiny412
ATtiny414
2 KB
ATtiny212
ATtiny214
8
14
Pins
Devices with different Flash memory sizes typically also have different SRAM and EEPROM.
2.1
Configuration Summary
2.1.1
Peripheral Summary
ATtiny212
ATtiny214
ATtiny412
ATtiny414
ATtiny416
Table 2-1. Peripheral Summary
Pins
8
14
8
14
20
SRAM
128B
128B
256B
256B
256B
Flash
2 KB
2 KB
4 KB
4 KB
4 KB
EEPROM
64B
64B
128B
128B
128B
Max. frequency (MHz)
20
20
20
20
20
16-bit Timer/Counter type A (TCA)
1
1
1
1
1
16-bit Timer/Counter type B (TCB)
1
1
1
1
1
12-bit Timer/Counter type D (TCD)
1
1
1
1
1
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ATtiny212/214/412/414/416
tinyAVR® 1-series Overview
ATtiny212
ATtiny214
ATtiny412
ATtiny414
ATtiny416
...........continued
Real-Time Counter (RTC)
1
1
1
1
1
USART
1
1
1
1
1
SPI
1
1
1
1
1
1
1
1
1
1
ADC
1
1
1
1
1
ADC channels
6
10
6
10
12
DAC
1
1
1
1
1
AC
1
1
1
1
1
AC inputs
1p/1n
1p/1n
1p/1n
1p/1n
2p/2n
Peripheral Touch Controller (PTC)
No
No
No
No
No
Configurable Custom Logic
1
1
1
1
1
Window Watchdog
1
1
1
1
1
Event System channels
6
6
6
6
6
General purpose I/O
6
12
6
12
18
External interrupts
6
12
6
12
18
CRCSCAN
1
1
1
1
1
TWI
(I2C)
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ATtiny212/214/412/414/416
Block Diagram
3.
Block Diagram
Figure 3-1. tinyAVR® 1-series Block Diagram
Analog peripherals
®
analog
Digital peripherals
analog
peripherals
Core components
UPDI
UPDI / RESET
CRC
CPU
analog
peripherals
Clocks/generators
OCD
To
detectors
Flash
SRAM
BUS Matrix
EEPROM
NVMCTRL
AINP[3:0]
AINN[1:0]
OUT
OUT
AIN[11:0]
X[13:0]
Y[13:0]
VREFA
LUTn-IN[2:0]
LUTn-OUT
WO[5:0]
WO
GPIOR
DAC [2:0]
ADC0 / PTC
AIN[11:0]
PORTS
AC [2:0]
ADC1
CCL
TCA0
TCB[1:0]
E
V
E
N
T
R
O
U
T
I
N
G
N
E
T
W
O
R
K
D
A
T
A
B
U
S
CPUINT
I
N
/
O
U
T
D
A
T
A
B
U
S
System
Management
MISO
MOSI
SCK
SS
SPI0
SDA
SCL
TWI0
POR
BOD
VLM
CLKCTRL
SLPCTRL
Clock Generation
CLKOUT
OSC20M
OSC32K
RTC
USART0
RST
Bandgap
TCD0
RXD
TXD
XCK
XDIR
Detectors/
References
RSTCTRL
WDT
WO[A,B,C,D]
PA[7:0]
PB[7:0]
PC[5:0]
TOSC1
XOSC32K
TOSC2
EXTCLK
EVSYS
EXTCLK
EVOUT[n:0]
Note: The block diagram represents the largest device of the tinyAVR®1-series, both in terms of pin count and Flash
size. See sections 2.1 Configuration Summary and 5. I/O Multiplexing and Considerations for an overview of the
features of the specific devices in this data sheet.
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ATtiny212/214/412/414/416
Pinout
4.
Pinout
4.1
8-Pin SOIC
VDD
1
8
GND
PA6
2
7
PA3 (EXTCLK)
PA7
3
6
PA0 (RESET/UPDI)
PA1
4
5
PA2
Power
Functionality
Power Supply
Programming/Debug
Ground
Clock/Crystal
Pin on VDD Power Domain
Digital Function Only
Analog Function
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Pinout
4.2
14-Pin SOIC
VDD
1
14
GND
PA4
2
13
PA3 (EXTCLK)
PA5
3
12
PA2
PA6
4
11
PA1
PA7
5
10
PA0 (RESET/UPDI)
(TOSC1) PB3
6
9
PB0
(TOSC2) PB2
7
8
PB1
Power
Functionality
Power Supply
Programming/Debug
Ground
Clock/Crystal
Pin on VDD Power Domain
Digital Function Only
Analog Function
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Pinout
4.3
20-Pin SOIC
VDD
1
20
GND
PA4
2
19
PA3 (EXTCLK)
PA5
3
18
PA2
PA6
4
17
PA1
PA7
5
16
PA0 (RESET/UPDI)
PB5
6
15
PC3
PB4
7
14
PC2
(TOSC1) PB3
8
13
PC1
(TOSC2) PB2
9
12
PC0
10
11
PB0
PB1
Power
Functionality
Power Supply
Programming/Debug
Ground
Clock/Crystal
Pin on VDD Power Domain
Digital Function Only
Analog Function
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Pinout
PC3
PC2
PC1
20 19
18
17
16
PA1
PA0 (RESET/UPDI)
20-Pin VQFN
PC0
(EXTCLK) PA3
2
14
PB0
GND
3
13
PB1
VDD
4
12
PB2 (TOSC2)
PA4
5
11
PB3 (TOSC1)
Note: It is recommended to
6
7
8
9
PB5
15
PA7
1
PA6
PA2
PA5
10
solder the large center pad to
ground for mechanical stability
Power
PB4
4.4
Functionality
Power Supply
Programming/Debug
Ground
Clock/Crystal
Pin on VDD Power Domain
Digital Function Only
Analog Function
© 2020 Microchip Technology Inc.
Complete Datasheet
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ATtiny212/214/412/414/416
I/O Multiplexing and Considerations
5.
I/O Multiplexing and Considerations
5.1
Multiplexed Signals
VQFN 20-Pin
SOIC 20-Pin
SOIC 14-Pin
Table 5-1. PORT Function Multiplexing, 14 and 20 Pins
Pin Name (1,2)
19
16
10
PA0
20
17
11
PA1
1
18
12
PA2
EVOUT0
AIN2
RxD(3)
MISO
EXTCLK
AIN3
XCK(3)
SCK
WO3
XDIR(3)
SS
WO4
Other/Special
ADC0
RESET/ UPDI
AIN0
AC0
DAC0
USART0
SPI0
TWI0
TCA0
AIN1
TxD(3)
MOSI
SDA(3)
TCD0
CCL
LUT0-IN1
SCL(3)
LUT0-IN2
LUT0-IN0
2
19
13
PA3
3
20
14
GND
4
1
1
VDD
5
2
2
PA4
AIN4
6
3
3
PA5
AIN5
OUT
7
4
4
PA6
AIN6
AINN0
8
5
5
PA7
AIN7
AINP0
9
6
PB5
AIN8
AINP1
WO2(3)
10
7
PB4
AIN9
AINN1
WO1(3)
CLKOUT
TCB0
WO5
WOA
WO
LUT0-OUT
WOB
MOSI(3)(4)
OUT
MISO(3)(4)
LUT1-OUT
LUT0-OUT(3)
WO0(3)
11
8
6
PB3
TOSC1
RxD
12
9
7
PB2
TOSC2, EVOUT1
TxD
13
10
8
PB1
AIN10
XCK
SDA
WO1
14
11
9
PB0
AIN11
XDIR
SCL
WO0
15
12
PC0
SCK(3)
16
13
PC1
MISO(3)(4)
17
14
PC2
18
15
PC3
WO2
WO(3)
WOC
WOD
LUT1-OUT(3)
MOSI(3)(4)
EVOUT2
SS(3)
WO3(3)
LUT1-IN0
Notes:
1. Pin names are of type Pxn, with x being the PORT instance (A, B) and n the pin number. The notation for
signals is PORTx_PINn. All pins can be used as event input.
2. All pins can be used for external interrupt, where pins Px2 and Px6 of each port have full asynchronous
detection.
3. Alternate pin positions. For selecting the alternate positions, refer to section 15. PORTMUX - Port Multiplexer.
4. Alternate pins for SPI MISO and MOSI are respectively at PA7 and PA6 for 14-pin devices and PC1 and PC2
for 20-pin devices.
Table 5-2. PORT Function Multiplexing, Eight Pins
SOIC 8-Pin
Pin Name
(1,2)
Other/
Special
6
PA0
RESET/UPDI AIN0
4
PA1
AIN1
5
PA2
EVOUT0
AIN2
7
PA3
EXTCLK
AIN3
OUT
8
GND
1
VDD
2
PA6
AIN6
AINN0
3
PA7
AIN7
AINP0
ADC0
© 2020 Microchip Technology Inc.
AC0
DAC0
OUT
USART0
SPI0
TWI0
TCA0
XDIR
SS
TxD(3)
TCB0
TCD0
CCL
MOSI
SDA
WO1
LUT0-IN1
RxD(3)
MISO
SCL
WO2
LUT0-IN2
XCK
SCK
TxD
MOSI(3)
RxD
MISO(3)
LUT0-IN0
Complete Datasheet
WO0/WO3
WO0
WO0(3)
WOA
LUT0-OUT
WOB
LUT1-OUT
DS40002287A-page 18
ATtiny212/214/412/414/416
I/O Multiplexing and Considerations
Notes:
1. Pin names are of type Pxn, with x being the PORT instance (A, B) and n the pin number. Notation for signals is
PORTx_PINn. All pins can be used as event inputs.
2. All pins can be used for external interrupts, where pins Px2 and Px6 of each port have full asynchronous
detection.
3. Alternate pin positions. For selecting the alternate positions, refer to section 15. PORTMUX - Port Multiplexer.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 19
ATtiny212/214/412/414/416
Memories
6.
Memories
6.1
Overview
The main memories are SRAM data memory, EEPROM data memory, and Flash program memory. Also, the
peripheral registers are located in the I/O memory space.
Table 6-1. Physical Properties of Flash Memory
Property
ATtiny212
ATtiny214
ATtiny412
ATtiny414
ATtiny416
Size
2 KB
2 KB
4 KB
4 KB
4 KB
Page size
64B
64B
64B
64B
64B
Number of pages 32
32
64
64
64
Start address
0x8000
0x8000
0x8000
0x8000
0x8000
Table 6-2. Physical Properties of SRAM
Property
ATtiny212
ATtiny214
ATtiny412
ATtiny414
ATtiny416
Size
128B
128B
256B
256B
256B
Start address
0x3F80
0x3F80
0x3F00
0x3F00
0x3F00
Table 6-3. Physical Properties of EEPROM
Property
ATtiny212
ATtiny214
ATtiny412
ATtiny414
ATtiny416
Size
64B
64B
128B
128B
128B
Page size
32B
32B
32B
32B
32B
Number of pages 2
2
4
4
4
Start address
0x1400
0x1400
0x1400
0x1400
0x1400
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ATtiny212/214/412/414/416
Memories
6.2
Memory Map
Figure 6-1. Memory Map
CPU Code space
0x0000
UPDI/CPU Data space
64 I/O Registers
0x0000 – 0x003F
960 Ext. I/O Registers
0x0040 – 0x0FFF
NVM I/O Registers and
Data
0x1000 – 0x13FF
0x1400
EEPROM 64/128B
0x1440 (For EEPROM 64B)/
0x1480 (For EEPROM 128B)
(Reserved)
0x3F80/0x3F00
Flash Code
2/4 KB
Internal SRAM
128/256B
0x3FFF
(Reserved)
0x8000
Flash Code
2/4 KB
0x87FF (For Flash 2K)/
0x8FFF (For Flash 4K)
6.3
In-System Reprogrammable Flash Program Memory
The ATtiny212/214/412/414/416 contains 2/4 KB on-chip in-system reprogrammable Flash memory for program
storage. Since all AVR instructions are 16 or 32-bit wide, the Flash is organized with 16-bit data width. For write
protection, the Flash program memory space can be divided into three sections (see the illustration below):
Bootloader section, Application code section, and Application data section, with restricted access rights among them.
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ATtiny212/214/412/414/416
Memories
The Program Counter (PC) is 11-bit wide to address the whole program memory. The procedure for writing Flash
memory is described in detail in the documentation of the Nonvolatile Memory Controller (NVMCTRL) peripheral.
The entire Flash memory is mapped in the memory space and is accessible with normal LD/ST instructions as well as
the LPM instruction. For LD/ST instructions, the Flash is mapped from address 0x8000. For the LPM instruction, the
Flash start address is 0x0000.
The ATtiny212/214/412/414/416 also has a CRC peripheral that is a host on the bus.
Figure 6-2. Flash and the Three Sections
FLASHSTART: 0x8000
BO OT
BOOTEND>0: 0x8000+BOOTEND*256
FLASH
AP PL ICA TIO N
CO DE
APPEND>0: 0x8000+APPEND*256
AP PL ICA TIO N
DA TA
FLASHEND
6.4
SRAM Data Memory
The 128/256 bytes SRAM is used for data storage and stack.
6.5
EEPROM Data Memory
The ATtiny212/214/412/414/416 has 64/128 bytes of EEPROM data memory. See also section 6.2 Memory Map.
The EEPROM memory supports single-byte read and write. The EEPROM is controlled by the Nonvolatile Memory
Controller (NVMCTRL).
6.6
User Row
In addition to the EEPROM, the ATtiny212/214/412/414/416 has one extra page of EEPROM memory that can be
used for firmware settings; the User Row (USERROW). This memory supports single-byte read and write as the
normal EEPROM. The CPU can write and read this memory as normal EEPROM, and the UPDI can write and read it
as a normal EEPROM memory if the part is unlocked. The User Row can be written by the UPDI when the part is
locked. USERROW is not affected by a chip erase.
6.7
Signature Bytes
All tinyAVR® microcontrollers have a 3-byte signature code that identifies the device. The three bytes reside in a
separate address space. For the device, the signature bytes are given in the following table.
Note: When the device is locked, only the System Information Block (SIB) can be accessed.
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ATtiny212/214/412/414/416
Memories
Table 6-4. Device ID
Device Name
6.8
Signature Bytes Address
0x00
0x01
0x02
ATtiny212
0x1E
0x91
0x21
ATtiny214
0x1E
0x91
0x20
ATtiny412
0x1E
0x92
0x23
ATtiny414
0x1E
0x92
0x22
ATtiny416
0x1E
0x92
0x21
I/O Memory
All ATtiny212/214/412/414/416 I/Os and peripherals are located in the I/O memory space. The I/O address range
from 0x00 to 0x3F can be accessed in a single cycle using IN and OUT instructions. The extended I/O memory space
from 0x0040 to 0x0FFF can be accessed by the LD/LDS/LDD and ST/STS/STD instructions, transferring data between
the 32 general purpose working registers and the I/O memory space.
I/O registers within the address range 0x00-0x1F are directly bit-accessible using the SBI and CBI instructions. In
these registers, the value of single bits can be checked by using the SBIS and SBIC instructions. Refer to the
Instruction Set section for more details.
For compatibility with future devices, reserved bits must be written to ‘0’ if accessed. Reserved I/O memory
addresses must never be written.
Some of the interrupt flags are cleared by writing a ‘1’ to them. On ATtiny212/214/412/414/416 devices, the CBI and
SBI instructions will only operate on the specified bit and can be used on registers containing such interrupt flags.
The CBI and SBI instructions work with registers 0x00-0x1F only.
General Purpose I/O Registers
The ATtiny212/214/412/414/416 devices provide four general purpose I/O registers. These registers can be used for
storing any information, and they are particularly useful for storing global variables and interrupt flags. General
purpose I/O registers, which reside in the address range 0x1C-0x1F, are directly bit-accessible using the SBI, CBI,
SBIS, and SBIC instructions.
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ATtiny212/214/412/414/416
Memories
6.8.1
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
GPIOR0
GPIOR1
GPIOR2
GPIOR3
7:0
7:0
7:0
7:0
6.8.2
7
6
5
4
3
2
1
0
GPIOR[7:0]
GPIOR[7:0]
GPIOR[7:0]
GPIOR[7:0]
Register Description
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.8.2.1
General Purpose I/O Register n
Name:
Offset:
Reset:
Property:
GPIORn
0x00 + n*0x01 [n=0..3]
0x00
-
These are general purpose registers that can be used to store data, such as global variables and flags, in the bitaccessible I/O memory space.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
GPIOR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – GPIOR[7:0] General Purpose I/O Register Byte
6.9
Memory Section Access from CPU and UPDI on Locked Device
The device can be locked so that the memories cannot be read using the UPDI. The locking protects both the Flash
(all Boot, Application Code, and Application Data sections), SRAM, and the EEPROM, including the FUSE data. This
prevents successful reading of application data or code using the debugger interface. Regular memory access from
within the application is still enabled.
The device is locked by writing a non-valid key to the LOCKBIT bit field in FUSE.LOCKBIT.
Table 6-5. Memory Access Unlocked (FUSE.LOCKBIT Valid Key)(1)
Memory Section
CPU Access
UPDI Access
Read
Write
Read
Write
SRAM
Yes
Yes
Yes
Yes
Registers
Yes
Yes
Yes
Yes
Flash
Yes
Yes
Yes
Yes
EEPROM
Yes
Yes
Yes
Yes
USERROW
Yes
Yes
Yes
Yes
SIGROW
Yes
No
Yes
No
Other fuses
Yes
No
Yes
Yes
Table 6-6. Memory Access Locked (FUSE.LOCKBIT Invalid Key)(1)
Memory Section
CPU Access
UPDI Access
Read
Write
Read
Write
SRAM
Yes
Yes
No
No
Registers
Yes
Yes
No
No
Flash
Yes
Yes
No
No
EEPROM
Yes
Yes
No
No
USERROW
Yes
Yes
No
Yes(2)
SIGROW
Yes
No
No
No
Other fuses
Yes
No
No
No
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 25
ATtiny212/214/412/414/416
Memories
Notes:
1. Read operations marked No in the tables may appear to be successful, but the data are not valid. Hence, any
attempt of code validation through the UPDI will fail on these memory sections.
2. In the Locked mode, the USERROW can be written using the Fuse Write command, but the current
USERROW values cannot be read out.
Important: The only way to unlock a device is through a CHIPERASE. No application data are retained.
6.10
Configuration and User Fuses (FUSE)
Fuses are part of the nonvolatile memory and hold the device configuration. The fuses are available from the device
power-up. The fuses can be read by the CPU or the UPDI but can only be programmed or cleared by the UPDI. The
configuration values stored in the fuses are written to their respective target registers at the end of the start-up
sequence.
The fuses for peripheral configuration (FUSE) are pre-programmed but can be altered by the user. Altered values in
the configuration fuse will be effective only after a Reset.
Note: When writing the fuses, all reserved bits must be written to ‘1’.
© 2020 Microchip Technology Inc.
Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.1
Signature Row Summary
Offset
Name
Bit Pos.
0x00
DEVICEID0
7:0
DEVICEID[7:0]
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
...
0x1F
0x20
0x21
0x22
0x23
0x24
0x25
DEVICEID1
DEVICEID2
SERNUM0
SERNUM1
SERNUM2
SERNUM3
SERNUM4
SERNUM5
SERNUM6
SERNUM7
SERNUM8
SERNUM9
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
DEVICEID[7:0]
DEVICEID[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
SERNUM[7:0]
7:0
7:0
7:0
7:0
7:0
7:0
TEMPSENSE[7:0]
TEMPSENSE[7:0]
OSC16ERR3V[7:0]
OSC16ERR5V[7:0]
OSC20ERR3V[7:0]
OSC20ERR5V[7:0]
6.10.2
7
6
5
4
3
2
1
0
Reserved
TEMPSENSE0
TEMPSENSE1
OSC16ERR3V
OSC16ERR5V
OSC20ERR3V
OSC20ERR5V
Signature Row Description
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 27
ATtiny212/214/412/414/416
Memories
6.10.2.1 Device ID n
Name:
Offset:
Default:
Property:
DEVICEIDn
0x00 + n*0x01 [n=0..2]
[Device ID]
-
Each device has a device ID identifying this device and its properties such as memory sizes, pin count, and die
revision. This ID can be used to identify a device and hence, the available features by software. The Device ID
consists of three bytes: SIGROW.DEVICEID[2:0].
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
DEVICEID[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – DEVICEID[7:0] Byte n of the Device ID
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 28
ATtiny212/214/412/414/416
Memories
6.10.2.2 Serial Number Byte n
Name:
Offset:
Default:
Property:
SERNUMn
0x03 + n*0x01 [n=0..9]
[device serial number]
-
Each device has an individual serial number, representing a unique ID. This ID can be used to identify a specific
device in the field. The serial number consists of ten bytes: SIGROW.SERNUM[9:0].
Bit
7
6
5
4
3
2
1
0
R
x
R
x
R
x
R
x
SERNUM[7:0]
Access
Default
R
x
R
x
R
x
R
x
Bits 7:0 – SERNUM[7:0] Serial Number Byte n
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 29
ATtiny212/214/412/414/416
Memories
6.10.2.3 Temperature Sensor Calibration n
Name:
Offset:
Default:
Property:
TEMPSENSEn
0x20 + n*0x01 [n=0..1]
[Temperature sensor calibration value]
-
The Temperature Sensor Calibration registers contain correction factors for temperature measurements from the onchip sensor. The ADC.SIGROW.TEMPSENSE0 is a correction factor for the gain/slope (unsigned), and
SIGROW.TEMPSENSE1 is a correction factor for the offset (signed).
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
TEMPSENSE[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – TEMPSENSE[7:0] Temperature Sensor Calibration Byte n
Refer to the ADC section for a description of how to use this register.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 30
ATtiny212/214/412/414/416
Memories
6.10.2.4 OSC16 Error at 3V
Name:
Offset:
Default:
Property:
OSC16ERR3V
0x22
[Oscillator frequency error value]
-
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
OSC16ERR3V[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – OSC16ERR3V[7:0] OSC16 Error at 3V
These registers contain the signed oscillator frequency error value relative to the nominal oscillator frequency when
running at an internal 16 MHz at 3V, as measured during production.
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.2.5 OSC16 Error at 5V
Name:
Offset:
Default:
Property:
OSC16ERR5V
0x23
[Oscillator frequency error value]
-
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
OSC16ERR5V[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – OSC16ERR5V[7:0] OSC16 Error at 5V
These registers contain the signed oscillator frequency error value relative to the nominal oscillator frequency when
running at an internal 16 MHz at 5V, as measured during production.
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.2.6 OSC20 Error at 3V
Name:
Offset:
Default:
Property:
OSC20ERR3V
0x24
[Oscillator frequency error value]
-
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
OSC20ERR3V[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – OSC20ERR3V[7:0] OSC20 Error at 3V
These registers contain the signed oscillator frequency error value relative to the nominal oscillator frequency when
running at an internal 20 MHz at 3V, as measured during production.
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.2.7 OSC20 Error at 5V
Name:
Offset:
Default:
Property:
OSC20ERR5V
0x25
[Oscillator frequency error value]
-
Bit
7
6
5
Access
Default
R
x
R
x
R
x
4
3
OSC20ERR5V[7:0]
R
R
x
x
2
1
0
R
x
R
x
R
x
Bits 7:0 – OSC20ERR5V[7:0] OSC20 Error at 5V
These registers contain the signed oscillator frequency error value relative to the nominal oscillator frequency when
running at an internal 20 MHz at 5V, as measured during production.
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ATtiny212/214/412/414/416
Memories
6.10.3
Fuse Summary - FUSE
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
WDTCFG
BODCFG
OSCCFG
Reserved
TCD0CFG
SYSCFG0
SYSCFG1
APPEND
BOOTEND
Reserved
LOCKBIT
7:0
7:0
7:0
6.10.4
7:0
7:0
7:0
7:0
7:0
7
6
5
WINDOW[3:0]
LVL[2:0]
4
3
2
1
SAMPFREQ
ACTIVE[1:0]
CMPAEN
CMPD
CMPC
RSTPINCFG[1:0]
OSCLOCK
CMPDEN
CMPCEN
CRCSRC[1:0]
7:0
CMPBEN
0
PERIOD[3:0]
SLEEP[1:0]
FREQSEL[1:0]
CMPB
CMPA
EESAVE
SUT[2:0]
APPEND[7:0]
BOOTEND[7:0]
LOCKBIT[7:0]
Fuse Description
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.4.1 Watchdog Configuration
Name:
Offset:
Default:
Property:
WDTCFG
0x00
0x00
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
7
6
5
4
3
2
WINDOW[3:0]
Access
Default
R
0
R
0
1
0
R
0
R
0
PERIOD[3:0]
R
0
R
0
R
0
R
0
Bits 7:4 – WINDOW[3:0] Watchdog Window Time-Out Period
This value is loaded into the WINDOW bit field of the Watchdog Control A (WDT.CTRLA) register during Reset.
Bits 3:0 – PERIOD[3:0] Watchdog Time-Out Period
This value is loaded into the PERIOD bit field of the Watchdog Control A (WDT.CTRLA) register during Reset.
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Complete Datasheet
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ATtiny212/214/412/414/416
Memories
6.10.4.2 BOD Configuration
Name:
Offset:
Default:
Property:
BODCFG
0x01
0x00
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
The bit values of this fuse register are written to the corresponding BOD configuration registers at the start-up.
Bit
Access
Default
7
R
0
6
LVL[2:0]
R
0
5
R
0
4
SAMPFREQ
R
0
3
2
1
ACTIVE[1:0]
R
0
0
SLEEP[1:0]
R
0
R
0
R
0
Bits 7:5 – LVL[2:0] BOD Level
This value is loaded into the LVL bit field of the BOD Control B (BOD.CTRLB) register during Reset.
Value
Name
Description
0x0
BODLEVEL0
1.8V
0x2
BODLEVEL2
2.6V
0x7
BODLEVEL7
4.2V
Notes:
• The values in the description are typical
• Refer to the BOD and POR Characteristics in Electrical Characteristics for maximum and minimum values
Bit 4 – SAMPFREQ BOD Sample Frequency
This value is loaded into the SAMPFREQ bit of the BOD Control A (BOD.CTRLA) register during Reset.
Value
Description
0x0
Sample frequency is 1 kHz
0x1
Sample frequency is 125 Hz
Bits 3:2 – ACTIVE[1:0] BOD Operation Mode in Active and Idle
This value is loaded into the ACTIVE bit field of the BOD Control A (BOD.CTRLA) register during Reset.
Value
Description
0x0
Disabled
0x1
Enabled
0x2
Sampled
0x3
Enabled with wake-up halted until BOD is ready
Bits 1:0 – SLEEP[1:0] BOD Operation Mode in Sleep
This value is loaded into the SLEEP bit field of the BOD Control A (BOD.CTRLA) register during Reset.
Value
Description
0x0
Disabled
0x1
Enabled
0x2
Sampled
0x3
Reserved
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Memories
6.10.4.3 Oscillator Configuration
Name:
Offset:
Default:
Property:
OSCCFG
0x02
0x02
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
Access
Default
7
OSCLOCK
R
0
6
5
4
3
2
1
0
FREQSEL[1:0]
R
R
1
0
Bit 7 – OSCLOCK Oscillator Lock
This Fuse bit is loaded to LOCK in CLKCTRL.OSC20MCALIBB during Reset.
Value
Description
0
Calibration registers of the OSC20M oscillator are accessible
1
Calibration registers of the OSC20M oscillator are locked
Bits 1:0 – FREQSEL[1:0] Frequency Select
This bit field selects the operation frequency of the 16/20 MHz internal oscillator (OSC20M) and determines the
respective factory calibration values to be written to CAL20M in CLKCTRL.OSC20MCALIBA and TEMPCAL20M in
CLKCTRL.OSC20MCALIBB.
Value
Description
0x1
Run at 16 MHz with corresponding factory calibration
0x2
Run at 20 MHz with corresponding factory calibration
Other
Reserved
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Memories
6.10.4.4 Timer Counter Type D Configuration
Name:
Offset:
Default:
Property:
TCD0CFG
0x04
0x00
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
The bit values of this fuse register are written to the corresponding bits in the TCD.FAULTCTRL register of TCD0 at
start-up.
Bit
Access
Default
7
CMPDEN
R
0
6
CMPCEN
R
0
5
CMPBEN
R
0
4
CMPAEN
R
0
3
CMPD
R
0
2
CMPC
R
0
1
CMPB
R
0
0
CMPA
R
0
Bits 4, 5, 6, 7 – CMPEN Compare x Enable
Value
Description
0
Compare x output on Pin is disabled
1
Compare x output on Pin is enabled
Bits 0, 1, 2, 3 – CMP Compare x
This bit selects the default state of Compare x after Reset, or when entering debug if FAULTDET is '1'.
Value
Description
0
Compare x default state is ‘0’
1
Compare x default state is ‘1’
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Memories
6.10.4.5 System Configuration 0
Name:
Offset:
Default:
Property:
SYSCFG0
0x05
0xF6
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
7
6
5
4
CRCSRC[1:0]
Access
Default
R
1
R
1
3
2
RSTPINCFG[1:0]
R
R
0
1
1
0
EESAVE
R
0
Bits 7:6 – CRCSRC[1:0] CRC Source
This bit field controls which section of the Flash will be checked by the CRCSCAN peripheral during Reset
initialization.
Value
Name
Description
0x0
FLASH
CRC of full Flash (boot, application code and application data)
0x1
BOOT
CRC of the boot section
0x2
BOOTAPP
CRC of application code and boot sections
0x3
NOCRC
No CRC
Bits 3:2 – RSTPINCFG[1:0] Reset Pin Configuration
This bit field selects the Reset/UPDI pin configuration.
Value
Description
0x0
GPIO
0x1
UPDI
0x2
RESET
Other
Reserved
Note: When configuring the RESET pin as GPIO, there is a potential conflict between the GPIO actively driving the
output, and a high-voltage UPDI enable sequence initiation. To avoid this, the GPIO output driver is disabled for 768
OSC32K cycles after a System Reset. Enable any interrupts for this pin only after this period.
Bit 0 – EESAVE EEPROM Save During Chip Erase
Note: If the device is locked, the EEPROM is always erased by a chip erase, regardless of this bit.
Value
0
1
Description
EEPROM erased during chip erase
EEPROM not erased under chip erase
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Memories
6.10.4.6 System Configuration 1
Name:
Offset:
Default:
Property:
SYSCFG1
0x06
0x07
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
7
6
5
4
3
Access
Default
2
R
1
1
SUT[2:0]
R
1
0
R
1
Bits 2:0 – SUT[2:0] Start-Up Time Setting
This bit field selects the start-up time between power-on and code execution.
Value
Description
0x0
0 ms
0x1
1 ms
0x2
2 ms
0x3
4 ms
0x4
8 ms
0x5
16 ms
0x6
32 ms
0x7
64 ms
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Memories
6.10.4.7 Application Code End
Name:
Offset:
Default:
Property:
APPEND
0x07
0x00
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
APPEND[7:0]
Access
Default
R
0
R
0
R
0
R
0
Bits 7:0 – APPEND[7:0] Application Code Section End
This bit field sets the end of the application code section in blocks of 256 bytes. The end of the application code
section will be set as (BOOT size) + (application code size). The remaining Flash will be application data. A value of
0x00 defines the Flash from BOOTEND*256 to the end of Flash as the application code. When both FUSE.APPEND
and FUSE.BOOTEND are 0x00, the entire Flash is the BOOT section.
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Memories
6.10.4.8 Boot End
Name:
Offset:
Default:
Property:
BOOTEND
0x08
0x00
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
7
6
5
Access
Default
R
0
R
0
R
0
4
3
BOOTEND[7:0]
R
R
0
0
2
1
0
R
0
R
0
R
0
Bits 7:0 – BOOTEND[7:0] Boot Section End
This bit field sets the end of the boot section in blocks of 256 bytes. A value of 0x00 defines the whole Flash as the
BOOT section. When both FUSE.APPEND and FUSE.BOOTEND are 0x00, the entire Flash is the BOOT section.
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Memories
6.10.4.9 Lockbits
Name:
Offset:
Default:
Property:
LOCKBIT
0x0A
0xC5
-
The default value given in this fuse description is the factory-programmed value and should not be mistaken for the
Reset value.
Bit
Access
Default
7
6
5
R/W
1
R/W
1
R/W
0
4
3
LOCKBIT[7:0]
R/W
R/W
0
0
2
1
0
R/W
1
R/W
0
R/W
1
Bits 7:0 – LOCKBIT[7:0] Lockbits
When the part is locked, UPDI cannot access the system bus, so it cannot read out anything but the System
Information Block (SIB).
Value
Description
0xC5
Valid key - memory access is unlocked
other
Invalid key - memory access is locked
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Peripherals and Architecture
7.
Peripherals and Architecture
7.1
Peripheral Address Map
The address map shows the base address for each peripheral. For a complete register description and summary for
each peripheral, refer to the respective sections.
Table 7-1. Peripheral Address Map
Base Address
Name
Description
0x0000
VPORTA
Virtual Port A
0x0004
VPORTB
Virtual Port B(1)
0x0008
VPORTC
Virtual Port C(1)
0x001C
GPIO
General Purpose I/O registers
0x0030
CPU
CPU
0x0040
RSTCTRL
Reset Controller
0x0050
SLPCTRL
Sleep Controller
0x0060
CLKCTRL
Clock Controller
0x0080
BOD
Brown-out Detector
0x00A0
VREF
Voltage Reference
0x0100
WDT
Watchdog Timer
0x0110
CPUINT
Interrupt Controller
0x0120
CRCSCAN
Cyclic Redundancy Check Memory Scan
0x0140
RTC
Real-Time Counter
0x0180
EVSYS
Event System
0x01C0
CCL
Configurable Custom Logic
0x0200
PORTMUX
Port Multiplexer
0x0400
PORTA
Port A Configuration
0x0420
PORTB
Port B Configuration(1)
0x0440
PORTC
Port C Configuration(1)
0x0600
ADC0
Analog-to-Digital Converter 0
0x0670
AC0
Analog Comparator 0
0x0680
DAC0
Digital-to-Analog Converter 0
0x0800
USART0
Universal Synchronous Asynchronous Receiver Transmitter 0
0x0810
TWI0
Two-Wire Interface 0
0x0820
SPI0
Serial Peripheral Interface 0
0x0A00
TCA0
Timer/Counter Type A 0
0x0A40
TCB0
Timer/Counter Type B 0
0x0A80
TCD0
Timer/Counter Type D 0
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Peripherals and Architecture
...........continued
Base Address
Name
Description
0x0F00
SYSCFG
System Configuration
0x1000
NVMCTRL
Nonvolatile Memory Controller
0x1100
SIGROW
Signature Row
0x1280
FUSES
Device-specific fuses
0x1300
USERROW
User Row
Note:
1. The availability of this register depends on the device pin count. PORTB/VPORTB is available for devices with
14 pins or more. PORTC/VPORTC is available for devices with 20 pins or more.
7.2
Interrupt Vector Mapping
Each of the interrupt vectors is connected to one peripheral instance, as shown in the table below. A peripheral can
have one or more interrupt sources, see the Interrupt section in the Functional Description of the respective
peripheral for more details on the available interrupt sources.
When the Interrupt condition occurs, an Interrupt flag (nameIF) is set in the Interrupt Flags register of the peripheral
(peripheral.INTFLAGS).
An interrupt is enabled or disabled by writing to the corresponding Interrupt Enable (nameIE) bit in the peripheral's
Interrupt Control (peripheral.INTCTRL) register.
The naming of the registers may vary slightly in some peripherals.
An interrupt request is generated when the corresponding interrupt is enabled, and the interrupt flag is set. The
interrupt request remains Active until the Interrupt flag is cleared. See the peripheral's INTFLAGS register for details
on how to clear interrupt flags.
Interrupts must be enabled globally for interrupt requests to be generated.
Table 7-2. Interrupt Vector Mapping
Vector Program Peripheral
Number Address Source
(word) (name)
Description
0
0x00
RESET
1
0x01
CRCSCAN_NMI Non-Maskable Interrupt available for CRCSCAN
2
0x02
BOD_VLM
Voltage Level Monitor interrupt
3
0x03
PORTA_PORT
Port A interrupt
4
0x04
PORTB_PORT
Port B interrupt(1)
5
0x05
PORTC_PORT
Port C interrupt(1)
6
0x06
RTC_CNT
Real-Time Counter interrupt
7
0x07
RTC_PIT
Periodic Interrupt Timer interrupt (in RTC peripheral)
8
0x08
TCA0_OVF
TCA0_LUNF
Normal: Timer Counter Type A Overflow interrupt.
Split: Timer Counter Type A Low Underflow interrupt.
9
0x09
TCA0_HUNF
Normal: Unused.
Split: Timer/Counter Type A High Underflow.
TCA0_CMP0
TCA0_LCMP0
Normal: Timer/Counter Type A Compare Channel 0 interrupt.
Split: Timer/Counter Type A Low byte Compare Channel 0 interrupt.
10
0x0A
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Peripherals and Architecture
...........continued
Vector Program Peripheral
Number Address Source
(word) (name)
Description
11
0x0B
TCA0_CMP1
TCA0_LCMP1
Normal: Timer/Counter Type A Compare Channel 1 interrupt.
Split: Timer/Counter Type A Low byte Compare Channel 1 interrupt.
12
0x0C
TCA0_CMP2
TCA0_LCMP2
Normal: Timer/Counter Type A Compare Channel 2 interrupt.
Split: Timer/Counter Type A Low byte Compare Channel 2 interrupt.
13
0x0D
TCB0_INT
Timer Counter Type B Capture interrupt
14
0x0E
TCD0_OVF
Timer/Counter Type D Overflow interrupt
15
0x0F
TCD0_TRIG
Timer/Counter Type D Trigger interrupt
16
0x10
AC0_AC
Analog Comparator interrupt
17
0x11
ADC0_RESRDY Analog-to-Digital Converter Result Ready interrupt
18
0x12
ADC0_WCOMP
Analog-to-Digital Converter Window Compare interrupt
19
0x13
TWI0_TWIS
Two-Wire Interface/I2C Client interrupt
20
0x14
TWI0_TWIM
Two-Wire Interface/I2C Host interrupt
21
0x15
SPI0_INT
Serial Peripheral Interface interrupt
22
0x16
USART0_RXC
Universal Asynchronous Receiver-Transmitter Receive Complete interrupt
23
0x17
USART0_DRE
Universal Asynchronous Receiver-Transmitter Data Ready interrupt
24
0x18
USART0_TXC
Universal Asynchronous Receiver-Transmitter Transmit Complete interrupt
25
0x19
NVMCTRL_EE
Nonvolatile Memory EEPROM Ready interrupt
Note:
1. The availability of the port pins depends on the device pin count. PORTB is available for devices with 14 pins
or more. PORTC is available for devices with 20 pins or more.
7.3
System Configuration (SYSCFG)
The system configuration contains the revision ID of the part. The revision ID is readable from the CPU, making it
useful for implementing application changes between part revisions.
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Peripherals and Architecture
7.3.1
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
Reserved
REVID
7:0
7.3.2
7
6
5
4
3
2
1
0
REVID[7:0]
Register Description
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Peripherals and Architecture
7.3.2.1
Device Revision ID Register
Name:
Offset:
Reset:
Property:
REVID
0x01
[revision ID]
-
This register is read-only and displays the device revision ID.
Bit
7
6
5
4
3
2
1
0
R
R
R
R
REVID[7:0]
Access
Reset
R
R
R
R
Bits 7:0 – REVID[7:0] Revision ID
This bit field contains the device revision. 0x00 = A, 0x01 = B, and so on.
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AVR® CPU
8.
AVR® CPU
8.1
Features
•
•
•
•
•
•
•
•
8.2
8-Bit, High-Performance AVR RISC CPU:
– 135 instructions
– Hardware multiplier
32 8-Bit Registers Directly Connected to the ALU
Stack in RAM
Stack Pointer Accessible in I/O Memory Space
Direct Addressing of up to 64 KB of Unified Memory
Efficient Support for 8-, 16-, and 32-Bit Arithmetic
Configuration Change Protection for System-Critical Features
Native On-Chip Debugging (OCD) Support:
– Two hardware breakpoints
– Change of flow, interrupt, and software breakpoints
– Run-time read-out of Stack Pointer (SP) register, Program Counter (PC), and Status Register (SREG)
– Register file read- and writable in Stopped mode
Overview
All AVR devices use the AVR 8-bit CPU. The CPU is able to access memories, perform calculations, control
peripherals, and execute instructions in the program memory. Interrupt handling is described in a separate section.
8.3
Architecture
To maximize performance and parallelism, the AVR CPU uses a Harvard architecture with separate buses for
program and data. The instructions in the program memory are executed with a single-level pipeline. While one
instruction is being executed, the next instruction is prefetched from the program memory. This enables instructions
to be executed on every clock cycle.
Refer to the Instruction Set Summary section for a summary of all AVR instructions.
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AVR® CPU
Figure 8-1. AVR® CPU Architecture
Register file
R31 (ZH)
R29 (YH)
R27 (XH)
R25
R23
R21
R19
R17
R15
R13
R11
R9
R7
R5
R3
R1
R30 (ZL)
R28 (YL)
R26 (XL)
R24
R22
R20
R18
R16
R14
R12
R10
R8
R6
R4
R2
R0
Program
Counter
Flash Program
Memory
Instruction
Register
Instruction
Decode
Data Memory
Stack
Pointer
Status
Register
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ALU
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AVR® CPU
8.4
Arithmetic Logic Unit (ALU)
The Arithmetic Logic Unit (ALU) supports arithmetic and logic operations between working registers or between a
constant and a working register. Also, single-register operations can be executed.
The ALU operates in a direct connection with all the 32 general purpose working registers in the register file. The
arithmetic operations between working registers or between a working register and an immediate operand are
executed in a single clock cycle, and the result is stored in the register file. After an arithmetic or logic operation, the
Status Register (CPU.SREG) is updated to reflect information about the result of the operation.
ALU operations are divided into three main categories – arithmetic, logical, and bit functions. Both 8- and 16-bit
arithmetic are supported, and the instruction set allows for an efficient implementation of the 32-bit arithmetic. The
hardware multiplier supports signed and unsigned multiplication and fractional formats.
8.4.1
Hardware Multiplier
The multiplier is capable of multiplying two 8-bit numbers into a 16-bit result. The hardware multiplier supports
different variations of signed and unsigned integer and fractional numbers:
•
•
•
•
Multiplication of signed/unsigned integers
Multiplication of signed/unsigned fractional numbers
Multiplication of a signed integer with an unsigned integer
Multiplication of a signed fractional number with an unsigned fractional number
A multiplication takes two CPU clock cycles.
8.5
8.5.1
Functional Description
Program Flow
After being reset, the CPU will execute instructions from the lowest address in the Flash program memory, 0x0000.
The Program Counter (PC) addresses the next instruction to be fetched.
The CPU supports instructions that can change the program flow conditionally or unconditionally and are capable of
addressing the whole address space directly. Most AVR instructions use a 16-bit word format, and a limited number
use a 32-bit format.
During interrupts and subroutine calls, the return address PC is stored on the stack as a word pointer. The stack is
allocated in the general data SRAM, and consequently, the stack size is only limited by the total SRAM size and the
usage of the SRAM. After the Stack Pointer (SP) is reset, it points to the highest address in the internal SRAM. The
SP is read/write accessible in the I/O memory space, enabling easy implementation of multiple stacks or stack areas.
The data SRAM can easily be accessed through the five different Addressing modes supported by the AVR CPU.
8.5.2
Instruction Execution Timing
The AVR CPU is clocked by the CPU clock, CLK_CPU. No internal clock division is applied. The figure below shows
the parallel instruction fetches and executions enabled by the Harvard architecture and the fast-access register file
concept. This is the basic pipelining concept enabling up to 1 MIPS/MHz performance with high efficiency.
Figure 8-2. The Parallel Instruction Fetches and Executions
T1
T2
T3
T4
clkCPU
1st Instruction Fetch
1st Instruction Execute
2nd Instruction Fetch
2nd Instruction Execute
3rd Instruction Fetch
3rd Instruction Execute
4th Instruction Fetch
The following figure shows the internal timing concept for the register file. In a single clock cycle, an ALU operation
using two register operands is executed, and the result is stored in the destination register.
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AVR® CPU
Figure 8-3. Single Cycle ALU Operation
T1
T2
T3
T4
clkCPU
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
8.5.3
Status Register
The Status Register (CPU.SREG) contains information about the result of the most recently executed arithmetic or
logic instructions. This information can be used for altering the program flow to perform conditional operations.
CPU.SREG is updated after all ALU operations, as specified in the Instruction Set Summary section, which will, in
many cases, remove the need for using the dedicated compare instructions, resulting in a faster and more compact
code. CPU.SREG is not automatically stored or restored when entering or returning from an Interrupt Service Routine
(ISR). Therefore, maintaining the Status Register between context switches must be handled by user-defined
software. CPU.SREG is accessible in the I/O memory space.
8.5.4
Stack and Stack Pointer
The stack is used for storing return addresses after interrupts and subroutine calls. Also, it can be used for storing
temporary data. The Stack Pointer (SP) always points to the top of the stack. The address pointed to by the SP is
stored in the Stack Pointer (CPU.SP) register. The CPU.SP is implemented as two 8-bit registers that are accessible
in the I/O memory space.
Data are pushed and popped from the stack using the instructions given in Table 8-1, or by executing interrupts. The
stack grows from higher to lower memory locations. This means that when pushing data onto the stack, the SP
decreases, and when popping data off the stack, the SP increases. The SP is automatically set to the highest
address of the internal SRAM after being reset. If the stack is changed, it must be set to point above the SRAM start
address (see the SRAM Data Memory topic in the Memories section for the SRAM start address), and it must be
defined before any subroutine calls are executed and before interrupts are enabled. See the table below for SP
details.
Table 8-1. Stack Pointer Instructions
Instruction
Stack Pointer
Description
PUSH
Decremented by 1 Data are pushed onto the stack
ICALL
RCALL
Decremented by 2 A return address is pushed onto the stack with a subroutine call or interrupt
POP
Incremented by 1
Data are popped from the stack
RET
RETI
Incremented by 2
A return address is popped from the stack with a return from subroutine or return
from interrupt
During interrupts or subroutine calls, the return address is automatically pushed on the stack as a word, and the SP is
decremented by two. The return address consists of two bytes and the Least Significant Byte (LSB) is pushed on the
stack first (at the higher address). As an example, a byte pointer return address of 0x0006 is saved on the stack as
0x0003 (shifted one bit to the right), pointing to the fourth 16-bit instruction word in the program memory. The return
address is popped off the stack with RETI (when returning from interrupts) and RET (when returning from subroutine
calls), and the SP is incremented by two.
The SP is decremented by one when data are pushed on the stack with the PUSH instruction, and incremented by
one when data are popped off the stack using the POP instruction.
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AVR® CPU
To prevent corruption when updating the SP from software, a write to SPL will automatically disable interrupts for up
to four instructions or until the next I/O memory write, whichever comes first.
8.5.5
Register File
The register file consists of 32 8-bit general purpose working registers used by the CPU. The register file is located in
a separate address space from the data memory.
All CPU instructions that operate on working registers have direct and single-cycle access to the register file. Some
limitations apply to which working registers can be accessed by an instruction, like the constant arithmetic and logic
instructions SBCI, SUBI, CPI, ANDI, ORI and LDI. These instructions apply to the second half of the working
registers in the register file, R16 to R31. See the AVR Instruction Set Manual for further details.
Figure 8-4. AVR® CPU General Purpose Working Registers
0 Addr.
7
0x00
R0
0x01
R1
0x02
R2
...
R13
R14
R15
R16
R17
0x0D
0x0E
0x0F
0x10
0x11
R26
R27
R28
R29
R30
R31
0x1A
0x1B
0x1C
0x1D
0x1E
0x1F
...
8.5.5.1
X-register Low Byte
X-register High Byte
Y-register Low Byte
Y-register High Byte
Z-register Low Byte
Z-register High Byte
The X-, Y-, and Z-Registers
Working registers R26...R31 have added functions besides their general purpose usage.
These registers can form 16-bit Address Pointers for indirect addressing of data memory. These three address
registers are called the X-register, Y-register, and Z-register. The Z-register can also be used as Address Pointer for
program memory.
Figure 8-5. The X-, Y-, and Z-Registers
Bit (individually)
7
X-register
15
Bit (individually)
7
Y-register
Bit (individually)
7
R29
15
7
R31
8
7
0
7
0
0
R28
0
YL
8
7
0
7
8
7
ZH
15
R26
XL
YH
Z-register
Bit (Z-register)
0
XH
Bit (X-register)
Bit (Y-register)
R27
0
R30
0
ZL
0
The lowest register address holds the Least Significant Byte (LSB), and the highest register address holds the Most
Significant Byte (MSB). These address registers can function as fixed displacement, automatic increment, and
automatic decrement, with different LD*/ST* instructions. See the Instruction Set Summary section for details.
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AVR® CPU
8.5.6
Accessing 16-bit Registers
Most of the registers for the ATtiny212/214/412/414/416 devices are 8-bit registers, but the devices also features a
few 16-bit registers. As the AVR data bus has a width of 8 bits, accessing the 16-bit requires two read or write
operations. All the 16-bit registers of the ATtiny212/214/412/414/416 devices are connected to the 8-bit bus through a
temporary (TEMP) register.
Figure 8-6. 16-Bit Register Write Operation
DATAH
TEMP
DATAL
Write Low Byte
A
V
R
D
A
T
A
B
U
S
DATAH
TEMP
DATAL
A
V
R
D
A
T
A
B
U
S
Write High Byte
For a 16-bit write operation, the low byte register (e.g. DATAL) of the 16-bit register must be written before the high
byte register (e.g. DATAH). Writing the low byte register will result in a write to the temporary (TEMP) register instead
of the low byte register, as shown in the left side of Figure 8-6. When the high byte register of the 16-bit register is
written, TEMP will be copied into the low byte of the 16-bit register in the same clock cycle, as shown in the right side
of Figure 8-6.
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Figure 8-7. 16-Bit Register Read Operation
DATAH
TEMP
DATAL
A
V
R
DATAH
D
A
T
A
B
U
S
TEMP
DATAL
A
V
R
D
A
T
A
B
U
S
Read High Byte
Read Low Byte
For a 16-bit read operation, the low byte register (e.g. DATAL) of the 16-bit register must be read before the high byte
register (e.g. DATAH). When the low byte register is read, the high byte register of the 16-bit register is copied into
the temporary (TEMP) register in the same clock cycle, as show in the left side of Figure 8-7. Reading the high byte
register will result in a read from TEMP instead of the high byte register, as shown in right side of Figure 8-7.
The described mechanism ensures that the low and high bytes of 16-bit registers are always accessed
simultaneously when reading or writing the registers.
Interrupts can corrupt the timed sequence if an interrupt is triggered during a 16-bit read/write operation and a 16-bit
register within the same peripheral is accessed in the interrupt service routine. To prevent this, interrupts should be
disabled when writing or reading 16-bit registers. Alternatively, the temporary register can be read before and
restored after the 16-bit access in the interrupt service routine.
8.5.6.1
Accessing 24-Bit Registers
For 24-bit registers, the read and write access is done in the same way as described for 16-bit registers, except there
are two temporary registers for 24-bit registers. The Most Significant Byte must be written last when writing to the
register, and the Least Significant Byte must be read first when reading the register.
8.5.7
Configuration Change Protection (CCP)
System critical I/O register settings are protected from accidental modification. Flash self-programming (via store to
NVM controller) is protected from accidental execution. This is handled globally by the Configuration Change
Protection (CCP) register.
Changes to the protected I/O registers or bits, or execution of protected instructions, are only possible after the CPU
writes a signature to the CCP register. The different signatures are listed in the description of the CCP register
(CPU.CCP).
There are two modes of operation: One for protected I/O registers, and one for protected self-programming.
8.5.7.1
Sequence for Write Operation to Configuration Change Protected I/O Registers
In order to write to registers protected by CCP, these steps are required:
1.
2.
The software writes the signature that enables change of protected I/O registers to the CCP bit field in the
CPU.CCP register.
Within four instructions, the software must write the appropriate data to the protected register.
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AVR® CPU
Most protected registers also contain a Write Enable/Change Enable/Lock bit. This bit must be written to ‘1’ in
the same operation as the data are written.
The protected change is immediately disabled if the CPU performs write operations to the I/O register or data
memory, if load or store accesses to Flash, NVMCTRL, or EEPROM are conducted, or if the SLEEP instruction
is executed.
8.5.7.2
Sequence for Execution of Self-Programming
In order to execute self-programming (the execution of writes to the NVM controller’s command register), the
following steps are required:
1.
2.
The software temporarily enables self-programming by writing the SPM signature to the CCP register
(CPU.CCP).
Within four instructions, the software must execute the appropriate instruction. The protected change is
immediately disabled if the CPU performs accesses to the Flash, NVMCTRL, or EEPROM, or if the SLEEP
instruction is executed.
Once the correct signature is written by the CPU, interrupts will be ignored for the duration of the configuration
change enable period. Any interrupt request (including non-maskable interrupts) during the CCP period will set the
corresponding Interrupt flag as normal, and the request is kept pending. After the CCP period is completed, any
pending interrupts are executed according to their level and priority.
8.5.8
On-Chip Debug Capabilities
The AVR CPU includes native On-Chip Debug (OCD) support. It contains some powerful debug capabilities to enable
profiling and detailed information about the CPU state. It is possible to alter the CPU state and resume code
execution. Also, normal debug capabilities like hardware Program Counter breakpoints, breakpoints on change of
flow instructions, breakpoints on interrupts, and software breakpoints (BREAK instruction) are present. Refer to the
Unified Program and Debug Interface section for details about OCD.
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AVR® CPU
8.6
Offset
0x00
...
0x03
0x04
0x05
...
0x0C
Register Summary
Name
7
6
5
4
3
2
1
0
V
N
Z
C
Reserved
CCP
7:0
CCP[7:0]
7:0
15:8
7:0
SP[7:0]
SP[15:8]
Reserved
0x0D
SP
0x0F
SREG
8.7
Bit Pos.
I
T
H
S
Register Description
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8.7.1
Configuration Change Protection
Name:
Offset:
Reset:
Property:
Bit
7
CCP
0x04
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CCP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – CCP[7:0] Configuration Change Protection
Writing the correct signature to this bit field allows changing protected I/O registers or executing protected
instructions within the next four CPU instructions executed.
All interrupts are ignored during these cycles. After these cycles are completed, the interrupts will automatically be
handled by the CPU, and any pending interrupts will be executed according to their level and priority.
When the protected I/O register signature is written, CCP[0] will read ‘1’ as long as the CCP feature is enabled.
When the protected self-programming signature is written, CCP[1] will read ‘1’ as long as the CCP feature is enabled.
CCP[7:2] will always read ‘0’.
Value
Name
Description
0x9D
SPM
Allow self-programming
0xD8
IOREG
Unlock protected I/O registers
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AVR® CPU
8.7.2
Stack Pointer
Name:
Offset:
Reset:
Property:
SP
0x0D
Top of stack
-
The CPU.SP register holds the Stack Pointer (SP) that points to the top of the stack. After being reset, the SP points
to the highest internal SRAM address.
Only the number of bits required to address the available data memory, including external memory (up to 64 KB), is
implemented for each device. Unused bits will always read ‘0’.
The CPU.SPL and CPU.SPH register pair represents the 16-bit value, CPU.SP. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
To prevent corruption when updating the SP from software, a write to CPU.SPL will automatically disable interrupts
for the next four instructions or until the next I/O memory write, whichever comes first.
Bit
15
14
13
12
11
10
9
8
R/W
R/W
R/W
R/W
3
2
1
0
R/W
R/W
R/W
R/W
SP[15:8]
Access
Reset
Bit
R/W
R/W
R/W
R/W
7
6
5
4
SP[7:0]
Access
Reset
R/W
R/W
R/W
R/W
Bits 15:8 – SP[15:8] Stack Pointer High Byte
These bits hold the MSB of the 16-bit register.
Bits 7:0 – SP[7:0] Stack Pointer Low Byte
These bits hold the LSB of the 16-bit register.
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AVR® CPU
8.7.3
Status Register
Name:
Offset:
Reset:
Property:
SREG
0x0F
0x00
-
The Status Register contains information about the result of the most recently executed arithmetic or logic
instructions. For details about the bits in this register and how they are influenced by different instructions, see the
Instruction Set Summary section.
Bit
Access
Reset
7
I
R/W
0
6
T
R/W
0
5
H
R/W
0
4
S
R/W
0
3
V
R/W
0
2
N
R/W
0
1
Z
R/W
0
0
C
R/W
0
Bit 7 – I Global Interrupt Enable Bit
Writing a ‘1’ to this bit enables interrupts on the device.
Writing a ‘0’ to this bit disables interrupts on the device, independent of the individual interrupt enable settings of the
peripherals.
This bit is not cleared by hardware while entering an Interrupt Service Routine (ISR) or set when the RETI instruction
is executed.
This bit can be set and cleared by software with the SEI and CLI instructions.
Changing the I bit through the I/O register results in a one-cycle Wait state on the access.
Bit 6 – T Transfer Bit
The bit copy instructions, Bit Load (BLD) and Bit Store (BST), use the T bit as source or destination for the operated
bit.
Bit 5 – H Half Carry Flag
This flag is set when there is a half carry in arithmetic operations that support this, and is cleared otherwise. Half
carry is useful in BCD arithmetic.
Bit 4 – S Sign Flag
This flag is always an Exclusive Or (XOR) between the Negative flag (N) and the Two’s Complement Overflow flag
(V).
Bit 3 – V Two’s Complement Overflow Flag
This flag is set when there is an overflow in arithmetic operations that support this, and is cleared otherwise.
Bit 2 – N Negative Flag
This flag is set when there is a negative result in an arithmetic or logic operation, and is cleared otherwise.
Bit 1 – Z Zero Flag
This flag is set when there is a zero result in an arithmetic or logic operation, and is cleared otherwise.
Bit 0 – C Carry Flag
This flag is set when there is a carry in an arithmetic or logic operation, and is cleared otherwise.
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NVMCTRL - Nonvolatile Memory Controller
9.
NVMCTRL - Nonvolatile Memory Controller
9.1
Features
•
•
•
•
•
•
9.2
Unified Memory
In-System Programmable
Self-Programming and Boot Loader Support
Configurable Sections for Write Protection:
– Boot section for boot loader code or application code
– Application code section for application code
– Application data section for application code or data storage
Signature Row for Factory-Programmed Data:
– ID for each device type
– Serial number for each device
– Calibration bytes for factory-calibrated peripherals
User Row for Application Data:
– Can be read and written from software
– Can be written from UPDI on locked device
– Content is kept after chip erase
Overview
The NVM Controller (NVMCTRL) is the interface between the CPU and Nonvolatile Memories (Flash, EEPROM,
Signature Row, User Row, and fuses). These are reprogrammable memory blocks that retain their values when they
are not powered. The Flash is mainly used for program storage and can also be used for data storage, while the
EEPROM, Signature Row, User Row, and fuses are used for data storage.
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NVMCTRL - Nonvolatile Memory Controller
9.2.1
Block Diagram
Figure 9-1. NVMCTRL Block Diagram
Nonvolatile
Memory Block
Program Memory Bus
`
Flash
EEPROM
Data Memory Bus
Signature Row
User Row
Fuses
Register access
NVMCTRL
9.3
Functional Description
9.3.1
Memory Organization
9.3.1.1
Flash
The Flash is divided into a set of pages. A page is the basic unit addressed when programming the Flash. It is only
possible to write or erase a whole page at a time. One page consists of several words.
The Flash can be divided into three sections in blocks of 256 bytes for different security. The three different sections
are BOOT, Application Code (APPCODE), and Application Data (APPDATA).
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NVMCTRL - Nonvolatile Memory Controller
Figure 9-2. Flash Sections
FLASHSTART : 0x8000
BOOT
BOOTEND>0: 0x8000+BOOTEND*256
APPLICATION
CODE
APPEND>0: 0x8000+APPEND*256
APPLICATION
DATA
Section Sizes
The sizes of these sections are set by the Boot Section End (FUSE.BOOTEND) fuse and the Application Code
Section End (FUSE.APPEND) fuse.
The fuses select the section sizes in blocks of 256 bytes. The BOOT section stretches from the start of the Flash until
BOOTEND. The APPCODE section runs from BOOTEND until APPEND. The remaining area is the APPDATA
section.
Table 9-1. Setting Up Flash Sections
BOOTEND
APPEND
BOOT Section
0
—
0 to FLASHEND
> 0
0
0 to 256*BOOTEND
> 0
≤ BOOTEND 0 to 256*BOOTEND
> 0
> BOOTEND 0 to 256*BOOTEND
APPCODE Section
APPDATA Section
—
—
256*BOOTEND to
FLASHEND
—
256*BOOTEND to
256*APPEND
—
256*BOOTEND to
FLASHEND
256*APPEND to
FLASHEND
If BOOTEND is written to ‘0’, the entire Flash is regarded as the BOOT section. If APPEND is written to ‘0’ and
BOOTEND > 0, the APPCODE section runs from BOOTEND to the end of Flash (no APPDATA section). When
APPEND ≤ BOOTEND, the APPCODE section is removed, and the APPDATA runs from BOOTEND to the end of
Flash. When APPEND > BOOTEND, the APPCODE section spreads from BOOTEND until APPEND. The remaining
area is the APPDATA section.
If there is no boot loader software, it is recommended to use the BOOT section for Application Code.
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NVMCTRL - Nonvolatile Memory Controller
Notes:
1. After Reset, the default vector table location is at the start of the APPCODE section. The peripheral interrupts
can be used in the code running in the BOOT section by relocating the interrupt vector table at the start of this
section. That is done by setting the IVSEL bit in the CPUINT.CTRLA register. Refer to the CPUINT section for
details.
2. If BOOTEND/APPEND, as resulted from BOOTEND and APPEND fuse setting, exceed the device
FLASHEND, the corresponding fuse setting is ignored, and the default value is used. Refer to “Fuse” in the
Memories section for default values.
Example 9-1. Size of Flash Sections
If FUSE.BOOTEND is written to 0x04 and FUSE.APPEND is written to 0x08, the first 4*256 bytes
will be BOOT, the next 4*256 bytes will be APPCODE, and the remaining Flash will be APPDATA.
Inter-Section Write Protection
Between the three Flash sections, directional write protection is implemented:
• The code in the BOOT section can write to APPCODE and APPDATA
• The code in APPCODE can write to APPDATA
• The code in APPDATA cannot write to Flash or EEPROM
Boot Section Lock and Application Code Section Write Protection
Additional to the inter-section write protection, the NVMCTRL provides a security mechanism to avoid unwanted
access to the Flash memory sections. Even if the CPU can never write to the BOOT section, a Boot Section Lock
(BOOTLOCK) bit in the Control B (NVMCTRL.CTRLB) register is provided to prevent the read and execution of code
from the BOOT section. This bit can be set only from the code executed in the BOOT section and has effect only
when leaving the BOOT section.
The Application Code Section Write Protection (APCWP) bit in the Control B (NVMCTRL.CTRLB) register can be set
to prevent further updates of the APPCODE section.
9.3.1.2
EEPROM
The EEPROM is divided into a set of pages where one page consists of multiple bytes. The EEPROM has byte
granularity on erase/write. Within one page, only the bytes marked to be updated will be erased/written. The byte is
marked by writing a new value to the page buffer for that address location.
9.3.1.3
User Row
The User Row is one extra page of EEPROM. This page can be used to store various data, such as calibration/
configuration data and serial numbers. This page is not erased by a chip erase. The User Row is written as normal
EEPROM, but also, it can be written through UPDI on a locked device.
9.3.2
9.3.2.1
Memory Access
Read
Reading of the Flash and EEPROM is done by using load instructions with an address according to the memory map.
Reading any of the arrays while a write or erase is in progress will result in a bus wait, and the instruction will be
suspended until the ongoing operation is complete.
9.3.2.2
Page Buffer Load
The page buffer is loaded by writing directly to the memories as defined in the memory map. Flash, EEPROM, and
User Row share the same page buffer, so only one section can be programmed at a time. The Least Significant bits
(LSb) of the address are used to select where in the page buffer data are written. The resulting data will be a binary
AND operation between the new and the previous content of the page buffer. The page buffer will automatically be
erased (all bits set) after:
• A device Reset
• Any page write or erase operation
• A Clear Page Buffer command
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NVMCTRL - Nonvolatile Memory Controller
•
9.3.2.3
A device wake-up from any sleep mode
Programming
For page programming, filling the page buffer and writing the page buffer into Flash, User Row, and EEPROM are
two separate operations.
Before programming a Flash page with the data in the page buffer, the Flash page must be erased. The page buffer
is also erased when the device enters a sleep mode. Programming an unerased Flash page will corrupt its content.
The Flash can either be written with the erase and write separately, or one command handling both:
Alternative 1:
1. Fill the page buffer.
2. Write the page buffer to Flash with the Erase and Write Page (ERWP) command.
Alternative 2:
1. Write to a location on the page to set up the address.
2. Perform an Erase Page (ER) command.
3. Fill the page buffer.
4. Perform a Write Page (WP) command.
The NVM command set supports both a single erase and write operation, and split Erase Page (ER) and Write Page
(WP) commands. This split commands enable shorter programming time for each command, and the erase
operations can be done during non-time-critical programming execution.
The EEPROM programming is similar, but only the bytes updated in the page buffer will be written or erased in the
EEPROM.
9.3.2.4
Commands
Reading the Flash/EEPROM and writing the page buffer is handled with normal load/store instructions. Other
operations, such as writing and erasing the memory arrays, are handled by commands in the NVM.
To execute a command in the NVM:
1. Confirm that any previous operation is completed by reading the Busy (EEBUSY and FBUSY) Flags in the
NVMCTRL.STATUS register.
2. Write the appropriate key to the Configuration Change Protection (CPU.CCP) register to unlock the NVM
Control A (NVMCTRL.CTRLA) register.
3. Write the desired command value to the CMD bit field in the Control A (NVMCTRL.CTRLA) register within the
next four instructions.
9.3.2.4.1 Write Page Command
The Write Page (WP) command of the Flash controller writes the content of the page buffer to the Flash or EEPROM.
If the write is to the Flash, the CPU will stop executing code as long as the Flash is busy with the write operation. If
the write is to the EEPROM, the CPU can continue executing code while the operation is ongoing.
The page buffer will automatically be cleared after the operation is finished.
9.3.2.4.2 Erase Page Command
The Erase Page (ER) command erases the current page. There must be one byte written in the page buffer for the
Erase Page (ER) command to take effect.
For erasing the Flash, first, write to one address in the desired page, then execute the command. The whole page in
the Flash will then be erased. The CPU will be halted while the erase is ongoing.
For the EEPROM, only the bytes written in the page buffer will be erased when the command is executed. To erase a
specific byte, write to its corresponding address before executing the command. To erase a whole page, all the bytes
in the page buffer have to be updated before executing the command. The CPU can continue running code while the
operation is ongoing.
The page buffer will automatically be cleared after the operation is finished.
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NVMCTRL - Nonvolatile Memory Controller
9.3.2.4.3 Erase/Write Page Command
The Erase and Write Page (ERWP) command is a combination of the Erase Page and Write Page commands, but
without clearing the page buffer after the Erase Page command: The erase/write operation first erases the selected
page, then it writes the content of the page buffer to the same page.
When executed on the Flash, the CPU will be halted when the operations are ongoing. When executed on EEPROM,
the CPU can continue executing code.
The page buffer will automatically be cleared after the operation is finished.
9.3.2.4.4 Page Buffer Clear Command
The Page Buffer Clear (PBC) command clears the page buffer. The contents of the page buffer will be all ‘1’s after
the operation. The CPU will be halted when the operation executes (seven CPU cycles).
9.3.2.4.5 Chip Erase Command
The Chip Erase (CHER) command erases the Flash and the EEPROM. The EEPROM is unaltered if the EEPROM
Save During Chip Erase (EESAVE) fuse in FUSE.SYSCFG0 is set. The Flash will not be protected by Boot Section
Lock (BOOTLOCK) bit or Application Code Section Write Protection (APCWP) bit in NVMCTRL.CTRLB register. The
memory will be all ‘1’s after the operation.
9.3.2.4.6 EEPROM Erase Command
The EEPROM Erase (EEER) command erases the EEPROM. The EEPROM will be all ‘1’s after the operation. The
CPU will be halted while the EEPROM is being erased.
9.3.2.4.7 Write Fuse Command
The Write Fuse (WFU) command writes the fuses. It can only be used by the UPDI; the CPU cannot start this
command.
Follow this procedure to use the Write Fuse command:
1. Write the address of the fuse to the Address (NVMCTRL.ADDR) register.
2. Write the data to be written to the fuse to the Data (NVMCTRL.DATA) register.
3. Execute the Write Fuse command.
4. After the fuse is written, a Reset is required for the updated value to take effect.
For reading fuses, use a regular read on the memory location.
9.3.2.5
Write Access after Reset
After a Power-on Reset (POR), the NVMCTRL rejects any write attempts to the NVM for a certain time. During this
period, the Flash Busy (FBUSY) and the EEPROM Busy (EEBUSY) bit field in the NVMCTRL.STATUS register will
read ‘1’. EEBUSY and FBUSY bit field must read ‘0’ before the page buffer can be filled, or NVM commands can be
issued.
This time-out period is disabled either by writing the Time-Out Disable bit (TOUTDIS) in the System Configuration 0
(FUSE.SYSCFG0) Fuse to ‘0’ or by configuring the RSTPINCFG bit field in FUSE.SYSCFG0 Fuse to UPDI.
9.3.3
Preventing Flash/EEPROM Corruption
During periods of low VDD, the Flash program or EEPROM data can be corrupted if the supply voltage is too low for
the CPU and the Flash/EEPROM to operate properly. These issues are the same on-board level systems using
Flash/EEPROM, and the same design solutions may be applied.
A Flash/EEPROM corruption can be caused by two situations when the voltage is too low:
1. A regular write sequence to the Flash, which requires a minimum voltage to operate correctly.
2. The CPU itself can execute instructions incorrectly when the supply voltage is too low.
See the Electrical Characteristics section for Maximum Frequency vs. VDD.
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NVMCTRL - Nonvolatile Memory Controller
Attention: Flash/EEPROM corruption can be avoided by taking these measures:
1. Keep the device in Reset during periods of insufficient power supply voltage. This can be done by
enabling the internal Brown-out Detector (BOD).
2. The voltage level monitor in the BOD can be used to prevent starting a write to the EEPROM close
to the BOD level.
3. If the detection levels of the internal BOD do not match the required detection level, an external low
VDD Reset protection circuit can be used. If a Reset occurs while a write operation is ongoing, the
write operation will be aborted.
9.3.4
Interrupts
Table 9-2. Available Interrupt Vectors and Sources
Offset
Name
Vector Description
Conditions
0x00
EEREADY
NVM
The EEPROM is ready for new write/erase operations.
When an interrupt condition occurs, the corresponding interrupt flag is set in the Interrupt Flags
(NVMCTRL.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding bit in the Interrupt Control
(NVMCTRL.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the NVMCTRL.INTFLAGS register for
details on how to clear interrupt flags.
9.3.5
Sleep Mode Operation
If there is no ongoing write operation, the NVMCTRL will enter a sleep mode when the system enters a sleep mode.
If a write operation is ongoing when the system enters a sleep mode, the NVM block, the NVM Controller, and the
system clock will remain ON until the write is finished. This is valid for all sleep modes, including Power-Down sleep
mode.
The EEPROM Ready interrupt will wake up the device only from Idle sleep mode.
The page buffer is cleared when waking up from sleep.
9.3.6
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 9-3. NVMCTRL - Registers under Configuration Change Protection
Register
Key
NVMCTRL.CTRLA
SPM
NVMCTRL.CTRLB
IOREG
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NVMCTRL - Nonvolatile Memory Controller
9.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
CTRLA
CTRLB
STATUS
INTCTRL
INTFLAGS
Reserved
7:0
7:0
7:0
7:0
7:0
0x06
DATA
0x08
ADDR
9.5
7
7:0
15:8
7:0
15:8
6
5
4
3
2
1
WRERROR
CMD[2:0]
BOOTLOCK
EEBUSY
0
APCWP
FBUSY
EEREADY
EEREADY
DATA[7:0]
DATA[15:8]
ADDR[7:0]
ADDR[15:8]
Register Description
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NVMCTRL - Nonvolatile Memory Controller
9.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
0x00
Configuration Change Protection
6
5
4
3
Access
Reset
2
R/W
0
1
CMD[2:0]
R/W
0
0
R/W
0
Bits 2:0 – CMD[2:0] Command
Write this bit field to issue a command. The Configuration Change Protection key for self-programming (SPM) has to
be written within four instructions before this write.
Value
Name
Description
0x0
No command
0x1
WP
Write page buffer to memory (NVMCTRL.ADDR selects which memory)
0x2
ER
Erase page (NVMCTRL.ADDR selects which memory)
0x3
ERWP Erase and write page (NVMCTRL.ADDR selects which memory)
0x4
PBC
Page buffer clear
0x5
CHER Chip erase: Erase Flash and EEPROM (unless EESAVE in FUSE.SYSCFG is ‘1’)
0x6
EEER
EEPROM Erase
0x7
WFU
Write fuse (only accessible through UPDI)
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NVMCTRL - Nonvolatile Memory Controller
9.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x01
0x00
Configuration Change Protection
6
5
4
3
Access
Reset
2
1
BOOTLOCK
R/W
0
0
APCWP
R/W
0
Bit 1 – BOOTLOCK Boot Section Lock
Writing this bit to ‘1’ locks the BOOT section from reading and instruction fetching.
If this bit is ‘1’, a read from the BOOT section will return ‘0’. A fetch from the BOOT section will also return ‘0’ as
instruction.
This bit can be written from the BOOT section only. It can only be cleared to ‘0’ by a Reset.
This bit will take effect only when the BOOT section is left the first time after the bit is written.
Bit 0 – APCWP Application Code Section Write Protection
Writing this bit to ‘1’ prevents further updates to the Application Code section.
This bit can only be written to ‘1’. It is cleared to ‘0’ only by Reset.
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NVMCTRL - Nonvolatile Memory Controller
9.5.3
Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x02
0x00
-
6
5
4
3
Access
Reset
2
WRERROR
R
0
1
EEBUSY
R
0
0
FBUSY
R
0
Bit 2 – WRERROR Write Error
This bit will read ‘1’ when a write error has happened. A write error could be writing to different sections before doing
a page write or writing to a protected area. This bit is valid for the last operation.
Bit 1 – EEBUSY EEPROM Busy
This bit will read ‘1’ when the EEPROM is busy with a command.
Bit 0 – FBUSY Flash Busy
This bit will read ‘1’ when the Flash is busy with a command.
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NVMCTRL - Nonvolatile Memory Controller
9.5.4
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x03
0x00
-
6
5
4
3
Access
Reset
2
1
0
EEREADY
R/W
0
Bit 0 – EEREADY EEPROM Ready Interrupt
Writing a ‘1’ to this bit enables the interrupt, which indicates that the EEPROM is ready for new write/erase
operations.
This is a level interrupt that will be triggered only when the EEREADY flag in the INTFLAGS register is set to ‘0’.
Thus, the interrupt must not be enabled before triggering an NVM command, as the EEREADY flag will not be set
before the NVM command issued. The interrupt may be disabled in the interrupt handler.
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NVMCTRL - Nonvolatile Memory Controller
9.5.5
Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x04
0x00
-
6
5
4
3
2
1
0
EEREADY
R/W
0
Access
Reset
Bit 0 – EEREADY EEREADY Interrupt Flag
This flag is set continuously as long as the EEPROM is not busy. This flag is cleared by writing a ‘1’ to it.
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NVMCTRL - Nonvolatile Memory Controller
9.5.6
Data
Name:
Offset:
Reset:
Property:
DATA
0x06
0x00
-
The NVMCTRL.DATAL and NVMCTRL.DATAH register pair represents the 16-bit value, NVMCTRL.DATA. The low
byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset
+ 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:0 – DATA[15:0] Data Register
This register is used by the UPDI for fuse write operations.
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NVMCTRL - Nonvolatile Memory Controller
9.5.7
Address
Name:
Offset:
Reset:
Property:
ADDR
0x08
0x00
-
The NVMCTRL.ADDRL and NVMCTRL.ADDRH register pair represents the 16-bit value, NVMCTRL.ADDR. The low
byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset
+ 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
ADDR[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
ADDR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:0 – ADDR[15:0] Address
The Address register contains the address to the last memory location that has been updated.
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CLKCTRL - Clock Controller
10.
CLKCTRL - Clock Controller
10.1
Features
•
•
•
•
All Clocks and Clock Sources are Automatically Enabled when Requested by Peripherals
Internal Oscillators:
– 16/20 MHz Oscillator (OSC20M)
– 32.768 kHz Ultra Low-Power Oscillator (OSCULP32K)
External Clock Options:
– 32.768 kHz Crystal Oscillator (XOSC32K)(1)
– External clock
Main Clock Features:
– Safe run-time switching
– Prescaler with 1x to 64x division in 12 different settings
Note:
1. Available for devices with 14 pins or more.
10.2
Overview
The Clock Controller (CLKCTRL) peripheral controls, distributes, and prescales the clock signals from the available
oscillators. The CLKCTRL supports internal and external clock sources.
The CLKCTRL is based on an automatic clock request system implemented in all peripherals on the device. The
peripherals will automatically request the clocks needed. If multiple clock sources are available, the request is routed
to the correct clock source.
The Main Clock (CLK_MAIN) is used by the CPU, RAM, and the I/O bus. The main clock source can be selected and
prescaled. Some peripherals can share the same clock source as the main clock or run asynchronously to the main
clock domain.
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CLKCTRL - Clock Controller
10.2.1
Block Diagram - CLKCTRL
Figure 10-1. CLKCTRL Block Diagram
NVM
RAM
CPU
CLK_CPU
CLKOUT
Other
Peripherals
CLK_PER
RTC
WDT
Int.
BOD
TCD
Prescaler
CLK_RTC
CLK_WDT
CLK_BOD
CLK_TCD
TCD
CLKCSEL
Main Clock Prescaler
CLK_MAIN
RTC
CLKSEL
Main Clock Switch
DIV32
XOSC32K
OSCULP32K
OSC20M
XOSC32K
SEL
OSC20M
Int. Oscillator
32.768 kHz ULP
Int. Oscillator
32.768 kHz
Ext. Crystal Osc.
TOSC2
TOSC1
EXTCLK
Note: The availability of the TOSC1, TOSC2 and the CLKOUT pin depends on the pin count of the device. See
section 5. I/O Multiplexing and Considerations for an overview of which pins are available for each device
represented in this data sheet.
The clock system consists of the Main Clock and other asynchronous clocks:
• Main Clock
This clock is used by the CPU, RAM, Flash, the I/O bus, and all peripherals connected to the I/O bus. It is
always running in Active and Idle sleep modes and can be running in Standby sleep mode if requested.
•
The main clock CLK_MAIN is prescaled and distributed by the Clock Controller:
• CLK_CPU is used by the CPU, SRAM and the NVMCTRL peripheral to access the non-volatile memory
• CLK_PER is used by all peripherals that are not listed under asynchronous clocks
Clocks running asynchronously to the Main Clock domain:
– CLK_RTC is used by the RTC/PIT. It will be requested when the RTC/PIT is enabled. The clock source for
CLK_RTC must only be changed if the peripheral is disabled.
– CLK_WDT is used by the WDT. It will be requested when the WDT is enabled.
– CLK_BOD is used by the BOD. It will be requested when the BOD is enabled in Sampled Mode.
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CLKCTRL - Clock Controller
– CLK_TCD is used by the TCD. It will be requested when the TCD is enabled. The clock source can only be
changed if the peripheral is disabled.
The clock source for the Main Clock domain is configured by writing to the Clock Select (CLKSEL) bits in the Main
Clock Control A (CLKCTRL.MCLKCTRLA) register. The asynchronous clock sources are configured by registers in
the respective peripheral.
10.2.2
Signal Description
Signal
Type
Description
CLKOUT
Digital output
CLK_PER output
10.3
Functional Description
10.3.1
Sleep Mode Operation
When a clock source is not used/requested, it will turn off. It is possible to request a clock source directly by writing a
'1' to the Run in Standby (RUNSTDBY) bit in the respective oscillator's Control A (CLKCTRL.[osc]CTRLA) register.
This will cause the oscillator to run constantly, except for Power-Down sleep mode. Additionally, when this bit is
written to '1', the oscillator start-up time is eliminated when the clock source is requested by a peripheral.
The main clock will always run in Active and Idle sleep mode. In Standby sleep mode, the main clock will only run if
any peripheral is requesting it, or the Run in Standby (RUNSTDBY) bit in the respective oscillator's Control A
(CLKCTRL.[osc]CTRLA) register is written to '1'.
In Power-Down sleep mode, the main clock will stop after all NVM operations are completed.
10.3.2
Main Clock Selection and Prescaler
All internal oscillators can be used as the main clock source for CLK_MAIN. The main clock source is selectable from
software and can be safely changed during normal operation.
Built-in hardware protection prevents unsafe clock switching.
Upon selection of an external clock source, a switch to the chosen clock source will only occur if edges are detected.
Until a sufficient number of clock edges are detected, the switch will not occur, and it will not be possible to change to
another clock source again without executing a Reset.
An ongoing clock source switch is indicated by the System Oscillator Changing (SOSC) flag in the Main Clock Status
(CLKCTRL.MCLKSTATUS) register. The stability of the external clock sources is indicated by the respective status
(EXTS and XOSC32KS in CLKCTRL.MCLKSTATUS) flags.
CAUTION
If an external clock source fails while used as CLK_MAIN source, only the WDT can provide a mechanism
to switch back via System Reset.
CLK_MAIN is fed into a prescaler before it is used by the peripherals (CLK_PER) in the device. The prescaler divides
CLK_MAIN by a factor from 1 to 64.
Figure 10-2. Main Clock and Prescaler
OSC20M
32.768 kHz Osc.
32.768 kHz crystal Osc.
External clock
CLK_MAIN
Main Clock Prescaler
(Div 1, 2, 4, 8, 16, 32,
64, 6, 10, 24, 48)
CLK_PER
The Main Clock and Prescaler configuration (CLKCTRL.MCLKCTRLA, CLKCTRL.MCLKCTRLB) registers are
protected by the Configuration Change Protection Mechanism, employing a timed write procedure for changing these
registers.
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CLKCTRL - Clock Controller
10.3.3
Main Clock After Reset
After any Reset, CLK_MAIN is provided by the 16/20 MHz Oscillator (OSC20M), with a prescaler division factor of 6.
Since the actual frequency of the OSC20M is determined by the Frequency Select (FREQSEL) bits of the Oscillator
Configuration (FUSE.OSCCFG) fuse, these frequencies are possible after Reset:
Table 10-1. Peripheral Clock Frequencies After Reset
CLK_MAIN as Per FREQSEL in FUSE.OSCCFG
Resulting CLK_PER
16 MHz
2.66 MHz
20 MHz
3.3 MHz
See the OSC20M description for further details.
10.3.4
Clock Sources
All internal clock sources are automatically enabled when they are requested by a peripheral. The crystal oscillator,
based on an external crystal, must be enabled by writing a '1' to the ENABLE bit in the 32.768 kHz Crystal Oscillator
Control A (CLKCTRL.XOSC32KCTRLA) register before it can serve as a clock source.
The respective Oscillator Status bits in the Main Clock Status (CLKCTRL.MCLKSTATUS) register indicate whether
the clock source is running and stable.
10.3.4.1 Internal Oscillators
The internal oscillators do not require any external components to run.
10.3.4.1.1 16/20 MHz Oscillator (OSC20M)
This oscillator can operate at multiple frequencies, selected by the value of the Frequency Select (FREQSEL) bits in
the Oscillator Configuration (FUSE.OSCCFG) fuse. The center frequencies are:
• 16 MHz
• 20 MHz
After a System Reset, FUSE.OSCCFG determines the initial frequency of CLK_MAIN.
During Reset, the calibration values for the OSC20M are loaded from fuses. There are two different Calibration bit
fields:
• The Calibration (CAL20M) bit field in the Calibration A (CLKCTRL.OSC20MCALIBA) register enables calibration
around the current center frequency
• The Oscillator Temperature Coefficient Calibration (TEMPCAL20M) bit field in the Calibration B
(CLKCTRL.OSC20MCALIBB) register enables adjustment of the slope of the temperature drift compensation
For applications requiring a more fine-tuned frequency setting than the oscillator calibration provides, factory-stored
frequency error after calibrations are available.
The oscillator calibration can be locked by the Oscillator Lock (OSCLOCK) Fuse (FUSE.OSCCFG). When this fuse is
‘1’, it is not possible to change the calibration. The calibration is locked if this oscillator is used as the main clock
source and the Lock Enable (LOCKEN) bit in the Control B (CLKCTRL.OSC20MCALIBB) register is ‘1’.
The Calibration bits are protected by the Configuration Change Protection Mechanism, requiring a timed write
procedure for changing the main clock and prescaler settings.
The start-up time of this oscillator is the analog start-up time plus four oscillator cycles. Refer to the Electrical
Characteristics section for the start-up time.
When changing the oscillator calibration value, the frequency may overshoot. If the oscillator is used as the main
clock (CLK_MAIN), it is recommended to change the main clock prescaler so that the main clock frequency does not
exceed ¼ of the maximum operation main clock frequency as described in the General Operating Ratings section.
The system clock prescaler can be changed back after the oscillator calibration value has been updated.
OSC20M Stored Frequency Error Compensation
This oscillator can operate at multiple frequencies, selected by the value of the Frequency Select (FREQSEL) bits in
the Oscillator Configuration (FUSE.OSCCFG) fuse at Reset. As previously mentioned, appropriate calibration values
are loaded to adjust to center frequency (OSC20M) and temperature drift compensation (TEMPCAL20M), meeting
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CLKCTRL - Clock Controller
the specifications defined in the internal oscillator characteristics. For applications requiring a wider operating range,
the relative factory stored frequency error after calibrations can be used. The four errors are measured with different
settings and are available in the signature row as signed byte values.
•
•
•
•
SIGROW.OSC16ERR3V is the frequency error from 16 MHz measured at 3V
SIGROW.OSC16ERR5V is the frequency error from 16 MHz measured at 5V
SIGROW.OSC20ERR3V is the frequency error from 20 MHz measured at 3V
SIGROW.OSC20ERR5V is the frequency error from 20 MHz measured at 5V
The error is stored as a compressed Q1.10 fixed point 8-bit value, not to lose resolution, where the MSb is the sign
bit, and the seven LSbs are the lower bits of the Q1.10.
BAUDact��� = BAUD����� +
BAUD����� * �����������
1024
The minimum legal BAUD register value is 0x40. The target BAUD register value must, therefore, not be lower than
0x4A to ensure that the compensated BAUD value stays within the legal range, even for parts with negative
compensation values. The example code below demonstrates how to apply this value for a more accurate USART
baud rate:
#include
/* Baud rate compensated with factory stored frequency error
/* Asynchronous communication without Auto-baud (Sync Field)
/* 16MHz Clock, 3V and 600 BAUD
int8_t sigrow_val
int32_t baud_reg_val
= SIGROW.OSC16ERR3V;
= 600;
assert (baud_reg_val >= 0x4A);
baud_reg_val *= (1024 + sigrow_val);
baud_reg_val /= 1024;
USART0.BAUD = (int16_t) baud_reg_val;
*/
*/
*/
// Read signed error
// Ideal BAUD register value
//
//
//
//
Verify legal min BAUD register value
Sum resolution + error
Divide by resolution
Set adjusted baud rate
10.3.4.1.2 32.768 kHz Oscillator (OSCULP32K)
The 32.768 kHz oscillator is optimized for Ultra Low-Power (ULP) operation. Power consumption is decreased at the
cost of decreased accuracy compared to an external crystal oscillator.
This oscillator provides the 1.024 kHz signal for the Real-Time Counter (RTC), the Watchdog Timer (WDT), and the
Brown-out Detector (BOD).
The start-up time of this oscillator is the oscillator start-up time plus four oscillator cycles. Refer to the Electrical
Characteristics section for the start-up time.
10.3.4.2 External Clock Sources
These external clock sources are available:
• External Clock from pin EXTCLK
• 32.768 kHz Crystal Oscillator on pins TOSC1 and TOSC2
• 32.768 kHz External Clock on pin TOSC1
10.3.4.2.1 External Clock (EXTCLK)
The EXTCLK is taken directly from the pin. This GPIO pin is automatically configured for EXTCLK if any peripheral is
requesting this clock.
This clock source has a start-up time of two cycles when first requested.
10.3.4.2.2 32.768 kHz Crystal Oscillator (XOSC32K)
This oscillator supports two input options: Either a crystal is connected to the pins TOSC1 and TOSC2, or an external
clock running at 32.768 kHz is connected to TOSC1. The input option must be configured by writing the Source
Select (SEL) bit in the XOSC32K Control A (CLKCTRL.XOSC32KCTRLA) register.
The XOSC32K is enabled by writing a '1' to its ENABLE bit in CLKCTRL.XOSC32KCTRLA. When enabled, the
configuration of the GPIO pins used by the XOSC32K is overridden as TOSC1, TOSC2 pins. The ENABLE bit needs
to be set for the oscillator to start running when requested.
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CLKCTRL - Clock Controller
The start-up time of a given crystal oscillator can be accommodated by writing to the Crystal Start-up Time (CSUT)
bits in CLKCTRL.XOSC32KCTRLA.
When XOSC32K is configured to use an external clock on TOSC1, the start-up time is fixed to two cycles.
10.3.5
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 10-2. CLKCTRL - Registers Under Configuration Change Protection
Register
Key
CLKCTRL.MCLKCTRLB
IOREG
CLKCTRL.MCLKLOCK
IOREG
CLKCTRL.XOSC32KCTRLA
IOREG
CLKCTRL.MCLKCTRLA
IOREG
CLKCTRL.OSC20MCTRLA
IOREG
CLKCTRL.OSC20MCALIBA
IOREG
CLKCTRL.OSC20MCALIBB
IOREG
CLKCTRL.OSC32KCTRLA
IOREG
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CLKCTRL - Clock Controller
10.4
Register Summary
Offset
Name
Bit Pos.
7
0x00
0x01
0x02
0x03
0x04
...
0x0F
0x10
0x11
0x12
0x13
...
0x17
0x18
0x19
...
0x1B
0x1C
MCLKCTRLA
MCLKCTRLB
MCLKLOCK
MCLKSTATUS
7:0
7:0
7:0
7:0
CLKOUT
10.5
6
5
4
3
2
XOSC32KS
OSC32KS
0
CLKSEL[1:0]
PEN
LOCKEN
SOSC
PDIV[3:0]
EXTS
1
OSC20MS
Reserved
OSC20MCTRLA
OSC20MCALIBA
OSC20MCALIBB
7:0
7:0
7:0
RUNSTDBY
CAL20M[5:0]
TEMPCAL20M[3:0]
LOCK
Reserved
OSC32KCTRLA
7:0
RUNSTDBY
Reserved
XOSC32KCTRLA
7:0
CSUT[1:0]
SEL
RUNSTDBY
ENABLE
Register Description
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CLKCTRL - Clock Controller
10.5.1
Main Clock Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CLKOUT
R/W
0
MCLKCTRLA
0x00
0x00
Configuration Change Protection
6
5
4
3
2
1
0
CLKSEL[1:0]
R/W
R/W
0
0
Bit 7 – CLKOUT System Clock Out
When this bit is written to '1', the system clock is output to the CLKOUT pin. The CLKOUT pin is available for devices
with 20 pins or more. See section 5. I/O Multiplexing and Considerations for more information.
When the device is in a sleep mode, there is no clock output unless a peripheral is using the system clock.
Bits 1:0 – CLKSEL[1:0] Clock Select
This bit field selects the source for the Main Clock (CLK_MAIN).
Value
Name
Description
0x0
OSC20M
16/20 MHz internal oscillator
0x1
OSCULP32K
32.768 kHz internal ultra low-power oscillator
0x2
XOSC32K
32.768 kHz external crystal oscillator
0x3
EXTCLK
External clock
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CLKCTRL - Clock Controller
10.5.2
Main Clock Control B
Name:
Offset:
Reset:
Property:
Bit
7
MCLKCTRLB
0x01
0x11
Configuration Change Protection
6
5
4
3
2
1
R/W
0
R/W
0
PDIV[3:0]
Access
Reset
R/W
1
R/W
0
0
PEN
R/W
1
Bits 4:1 – PDIV[3:0] Prescaler Division
If the Prescaler Enable (PEN) bit is written to ‘1’, this bit field defines the division ratio of the main clock prescaler.
This bit field can be written during run-time to vary the clock frequency of the system to suit the application
requirements.
The user software must ensure a correct configuration of input frequency (CLK_MAIN) and prescaler settings, such
that the resulting frequency of CLK_PER never exceeds the allowed maximum (see Electrical Characteristics).
Value
Description
Value
Division
0x0
2
0x1
4
0x2
8
0x3
16
0x4
32
0x5
64
0x8
6
0x9
10
0xA
12
0xB
24
0xC
48
other
Reserved
Bit 0 – PEN Prescaler Enable
This bit must be written '1' to enable the prescaler. When enabled, the division ratio is selected by the PDIV bit field.
When this bit is written to '0', the main clock will pass through undivided (CLK_PER=CLK_MAIN), regardless of the
value of PDIV.
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ATtiny212/214/412/414/416
CLKCTRL - Clock Controller
10.5.3
Main Clock Lock
Name:
Offset:
Reset:
Property:
Bit
7
MCLKLOCK
0x02
Based on OSCLOCK in FUSE.OSCCFG
Configuration Change Protection
6
5
4
3
Access
Reset
2
1
0
LOCKEN
R/W
x
Bit 0 – LOCKEN Lock Enable
Writing this bit to '1' will lock the CLKCTRL.MCLKCTRLA and CLKCTRL.MCLKCTRLB registers and, if applicable,
the calibration settings for the current main clock source from further software updates. Once locked, the
CLKCTRL.MCLKLOCK registers cannot be accessed until the next hardware Reset.
This protects the CLKCTRL.MCLKCTRLA and CLKCTRL.MCLKCTRLB registers and calibration settings for the main
clock source from unintentional modification by software.
At Reset, the LOCKEN bit is loaded based on the OSCLOCK bit in FUSE.OSCCFG.
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CLKCTRL - Clock Controller
10.5.4
Main Clock Status
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
EXTS
R
0
MCLKSTATUS
0x03
0x00
-
6
XOSC32KS
R
0
5
OSC32KS
R
0
4
OSC20MS
R
0
3
2
1
0
SOSC
R
0
Bit 7 – EXTS External Clock Status
Value
Description
0
EXTCLK has not started
1
EXTCLK has started
Bit 6 – XOSC32KS XOSC32K Status
The Status bit will only be available if the source is requested as the main clock or by another module. If the oscillator
RUNSTDBY bit is set, but the oscillator is unused/not requested, this bit will be ‘0’.
Value
Description
0
XOSC32K is not stable
1
XOSC32K is stable
Bit 5 – OSC32KS OSCULP32K Status
The Status bit will only be available if the source is requested as the main clock or by another module. If the oscillator
RUNSTDBY bit is set, but the oscillator is unused/not requested, this bit will be ‘0’.
Value
Description
0
OSCULP32K is not stable
1
OSCULP32K is stable
Bit 4 – OSC20MS OSC20M Status
The Status bit will only be available if the source is requested as the main clock or by another module. If the oscillator
RUNSTDBY bit is set, but the oscillator is unused/not requested, this bit will be ‘0’.
Value
Description
0
OSC20M is not stable
1
OSC20M is stable
Bit 0 – SOSC Main Clock Oscillator Changing
Value
Description
0
The clock source for CLK_MAIN is not undergoing a switch
1
The clock source for CLK_MAIN is undergoing a switch and will change as soon as the new source is
stable
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Complete Datasheet
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ATtiny212/214/412/414/416
CLKCTRL - Clock Controller
10.5.5
16/20 MHz Oscillator Control A
Name:
Offset:
Reset:
Property:
Bit
7
OSC20MCTRLA
0x10
0x00
Configuration Change Protection
6
5
4
3
Access
Reset
2
1
RUNSTDBY
R/W
0
0
Bit 1 – RUNSTDBY Run in Standby
This bit forces the oscillator ON in all modes, even when unused by the system. In Standby sleep mode, this can be
used to ensure immediate wake-up and not waiting for the oscillator start-up time.
When not requested by peripherals, no oscillator output is provided.
It takes four oscillator cycles to open the clock gate after a request, but the oscillator analog start-up time will be
removed when this bit is set.
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ATtiny212/214/412/414/416
CLKCTRL - Clock Controller
10.5.6
16/20 MHz Oscillator Calibration A
Name:
Offset:
Reset:
Property:
Bit
7
OSC20MCALIBA
0x11
Based on FREQSEL in FUSE.OSCCFG
Configuration Change Protection
6
Access
Reset
5
4
R/W
x
R/W
x
3
2
CAL20M[5:0]
R/W
R/W
x
x
1
0
R/W
x
R/W
x
Bits 5:0 – CAL20M[5:0] Calibration
This bit field changes the frequency around the current center frequency of the OSC20M for fine-tuning.
At Reset, the factory-calibrated values are loaded based on the FREQSEL bits in FUSE.OSCCFG.
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ATtiny212/214/412/414/416
CLKCTRL - Clock Controller
10.5.7
16/20 MHz Oscillator Calibration B
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
LOCK
R
x
OSC20MCALIBB
0x12
Based on FUSE.OSCCFG
Configuration Change Protection
6
5
4
3
R/W
x
2
1
TEMPCAL20M[3:0]
R/W
R/W
x
x
0
R/W
x
Bit 7 – LOCK Oscillator Calibration Locked by Fuse
When this bit is set, the calibration settings in CLKCTRL.OSC20MCALIBA and CLKCTRL.OSC20MCALIBB cannot
be changed.
At Reset, the value is loaded from the OSCLOCK bit in the Oscillator Configuration (FUSE.OSCCFG) fuse.
Bits 3:0 – TEMPCAL20M[3:0] Oscillator Temperature Coefficient Calibration
This bit field tunes the slope of the temperature compensation.
At Reset, the factory-calibrated values are loaded based on the FREQSEL bits in FUSE.OSCCFG.
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CLKCTRL - Clock Controller
10.5.8
32.768 kHz Oscillator Control A
Name:
Offset:
Reset:
Property:
Bit
7
OSC32KCTRLA
0x18
0x00
Configuration Change Protection
6
5
4
3
Access
Reset
2
1
RUNSTDBY
R/W
0
0
Bit 1 – RUNSTDBY Run in Standby
This bit forces the oscillator ON in all modes, even when unused by the system. In Standby sleep mode, this can be
used to ensure immediate wake-up and not waiting for the oscillator start-up time.
When not requested by peripherals, no oscillator output is provided.
It takes four oscillator cycles to open the clock gate after a request, but the oscillator analog start-up time will be
removed when this bit is set.
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ATtiny212/214/412/414/416
CLKCTRL - Clock Controller
10.5.9
32.768 kHz Crystal Oscillator Control A
Name:
Offset:
Reset:
Property:
XOSC32KCTRLA
0x1C
0x00
Configuration Change Protection
The SEL and CSUT bits cannot be changed as long as the ENABLE bit is set, or the XOSC32K Stable (XOSC32KS)
bit in CLKCTRL.MCLKSTATUS is high.
To change settings safely, write a '0' to the ENABLE bit and wait until XOSC32KS is '0' before re-enabling the
XOSC32K with new settings.
Bit
7
6
5
4
3
CSUT[1:0]
Access
Reset
R/W
0
R/W
0
2
SEL
R/W
0
1
RUNSTDBY
R/W
0
0
ENABLE
R/W
0
Bits 5:4 – CSUT[1:0] Crystal Start-Up Time
This bit field selects the start-up time for the XOSC32K. It is write-protected when the oscillator is enabled
(ENABLE=1).
If SEL=1, the start-up time will not be applied.
Value
Name
Description
0x0
1K
1k cycles
0x1
16K
16k cycles
0x2
32K
32k cycles
0x3
64K
64k cycles
Bit 2 – SEL Source Select
This bit selects the external source type. It is write-protected when the oscillator is enabled (ENABLE=1).
Value
Description
0
External crystal
1
External clock on TOSC1 pin
Bit 1 – RUNSTDBY Run in Standby
Writing this bit to '1' starts the crystal oscillator and forces the oscillator ON in all modes, even when unused by the
system if the ENABLE bit is set. In Standby sleep mode, this can be used to ensure immediate wake-up and not
waiting for oscillator start-up time. When this bit is '0', the crystal oscillator is only running when requested, and the
ENABLE bit is set.
The output of XOSC32K is not sent to other peripherals unless it is requested by one or more peripherals.
When the RUNSTDBY bit is set, there will only be a delay of two to three crystal oscillator cycles after a request until
the oscillator output is received, if the initial crystal start-up time has already completed.
Depending on the RUNSTDBY bit, the oscillator will be turned ON all the time if the device is in Active, Idle, or
Standby sleep mode, or only be enabled when requested.
This bit is I/O protected to prevent any unintentional enabling of the oscillator.
Bit 0 – ENABLE Enable
When this bit is written to '1', the configuration of the respective input pins is overridden to TOSC1 and TOSC2. Also,
the Source Select (SEL) and Crystal Start-Up Time (CSUT) bits become read-only.
This bit is I/O protected to prevent any unintentional enabling of the oscillator.
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
11.
SLPCTRL - Sleep Controller
11.1
Features
•
•
•
11.2
Power Management for Adjusting Power Consumption and Functions
Three Sleep Modes:
– Idle
– Standby
– Power-Down
Configurable Standby Mode where Peripherals Can Be Configured as ON or OFF
Overview
Sleep modes are used to shut down peripherals and clock domains in the device in order to save power. The Sleep
Controller (SLPCTRL) controls and handles the transitions between Active and sleep modes.
There are four modes available: One Active mode in which software is executed, and three sleep modes. The
available sleep modes are Idle, Standby and Power-Down.
All sleep modes are available and can be entered from the Active mode. In Active mode, the CPU is executing
application code. When the device enters sleep mode, the program execution is stopped. The application code
decides which sleep mode to enter and when.
Interrupts are used to wake the device from sleep. The available interrupt wake-up sources depend on the configured
sleep mode. When an interrupt occurs, the device will wake up and execute the Interrupt Service Routine before
continuing normal program execution from the first instruction after the SLEEP instruction. Any Reset will take the
device out of sleep mode.
The content of the register file, SRAM and registers, is kept during sleep. If a Reset occurs during sleep, the device
will reset, start and execute from the Reset vector.
11.2.1
Block Diagram
Figure 11-1. Sleep Controller in the System
SLEEP Instruction
SLPCTRL
Interrupt Request
CPU
Sleep State
Interrupt Request
Peripheral
11.3
11.3.1
Functional Description
Initialization
To put the device into a sleep mode, follow these steps:
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
1.
Configure and enable the interrupts that are able to wake the device from sleep.
Also, enable global interrupts.
WARNING
2.
If there are no interrupts enabled when going to sleep, the device cannot wake up again. Only a
Reset will allow the device to continue operation.
Select which sleep mode to enter and enable the Sleep Controller by writing to the Sleep Mode (SMODE) bit
field and the Enable (SEN) bit in the Control A (SLPCTRL.CTRLA) register.
The SLEEP instruction must be executed to make the device go to sleep.
11.3.2
Operation
11.3.2.1 Sleep Modes
In addition to Active mode, there are three different sleep modes with decreasing power consumption and
functionality.
Idle
Standby
PowerDown
The CPU stops executing code. No peripherals are disabled, and all interrupt sources can wake the
device.
The user can configure peripherals to be enabled or not, using the respective RUNSTBY bit. This
means that the power consumption is highly dependent on what functionality is enabled, and thus may
vary between the Idle and Power-Down levels.
SleepWalking is available for the ADC module.
BOD, WDT, and PIT (a component of the RTC) are active.
The only wake-up sources are the pin change interrupt, PIT, VLM, TWI address match, and CCL.
Table 11-1. Sleep Mode Activity Overview for Peripherals
Peripheral
Active in Sleep Mode
Idle
Standby
Power-Down
-
-
-
RTC
X
X(1,2)
X(2)
WDT
X
X
X
BOD
X
X
X
EVSYS
X
X
X
CCL
X
X(1)
-
ACn
X
X(1)
-
ADCn
X
X(1)
-
DACn
X
X(1)
-
TCBn
X
X(1)
-
All other peripherals
X
-
-
CPU
Notes:
1. For the peripheral to run in Standby sleep mode, the RUNSTDBY bit of the corresponding peripheral must be
set.
2. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY bit to be set.
In Power-Down sleep mode, only the PIT functionality is available.
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
Table 11-2. Sleep Mode Activity Overview for Clock Sources
Clock Source
Active in Sleep Mode
Idle
Standby
Power-Down
Main clock source
X
X(1)
-
RTC clock source
X
X(1,2)
X(2)
WDT oscillator
X
X
X
BOD oscillator(3)
X
X
X
CCL clock source
X
X(1)
-
TCD clock source
X
-
-
Notes:
1. For the clock source to run in Standby sleep mode, the RUNSTDBY bit of the requesting peripheral must be
set.
2. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY bit to be set.
In Power-Down sleep mode, only the PIT functionality is available.
3. The Sampled mode only.
Table 11-3. Sleep Mode Wake-up Sources
Wake-up Sources
Active in Sleep Mode
Idle
Standby
Power-Down
PORT Pin interrupt
X
X
X(1)
BOD VLM interrupts
X
X
X
RTC interrupts
X
X(2,3)
X(3)
TWIn Address Match interrupt
X
X
X
USARTn Start-of-Frame interrupts
X
X
-
ADCn interrupts
X
X
-
TCBn Capture interrupt
X
X
-
All other interrupts
X
-
-
Notes:
1. The I/O pin must be configured according to Asynchronous Sensing Pin Properties in the PORT section.
2. For the peripheral to run in Standby sleep mode, the RUNSTDBY bit of the corresponding peripheral must be
set.
3. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY bit to be set.
In Power-Down sleep mode, only the PIT functionality is available.
11.3.2.2 Wake-up Time
The normal wake-up time for the device is six main clock cycles (CLK_PER), plus the time it takes to start the main
clock source:
• In Idle sleep mode, the main clock source is kept running to eliminate additional wake-up time.
• In Standby sleep mode, the main clock might be running depending on the peripheral configuration.
• In Power-Down sleep mode, only the ULP 32.768 kHz oscillator and the RTC clock may be running if it is used
by the BOD or WDT. All other clock sources will be OFF.
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Complete Datasheet
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
Table 11-4. Sleep Modes and Start-up Time
Sleep Mode
Start-up Time
IDLE
6 CLK
Standby
6 CLK + OSC start-up
Power-Down
6 CLK + OSC start-up
The start-up time for the different clock sources is described in the Clock Controller (CLKCTRL) section.
In addition to the normal wake-up time, it is possible to make the device wait until the BOD is ready before executing
code. This is done by writing 0x3 to the BOD Operation mode in Active and Idle bits (ACTIVE) in the BOD
Configuration fuse (FUSE.BODCFG). If the BOD is ready before the normal wake-up time, the total wake-up time will
be the same. If the BOD takes longer than the normal wake-up time, the wake-up time will be extended until the BOD
is ready. This ensures correct supply voltage whenever code is executed.
11.3.3
Debug Operation
During run-time debugging, this peripheral will continue normal operation. The SLPCTRL is only affected by a break
in the debug operation: If the SLPCTRL is in a sleep mode when a break occurs, the device will wake up, and the
SLPCTRL will go to Active mode, even if there are no pending interrupt requests.
If the peripheral is configured to require periodic service by the CPU through interrupts or similar, improper operation
or data loss may result during halted debugging.
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
11.4
Register Summary
Offset
Name
Bit Pos.
0x00
CTRLA
7:0
11.5
7
6
5
4
3
2
1
SMODE[1:0]
0
SEN
Register Description
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ATtiny212/214/412/414/416
SLPCTRL - Sleep Controller
11.5.1
Control A
Name:
Offset:
Reset:
Property:
CTRLA
0x00
0x00
-
Bit
7
6
5
4
3
Access
Reset
R
0
R
0
R
0
R
0
R
0
2
1
SMODE[1:0]
R/W
R/W
0
0
0
SEN
R/W
0
Bits 2:1 – SMODE[1:0] Sleep Mode
Writing these bits selects which sleep mode to enter when the Sleep Enable (SEN) bit is written to ‘1’ and the SLEEP
instruction is executed.
Value
Name
Description
0x0
IDLE
Idle sleep mode enabled
0x1
STANDBY
Standby sleep mode enabled
0x2
PDOWN
Power-Down sleep mode enabled
other
Reserved
Bit 0 – SEN Sleep Enable
This bit must be written to ‘1’ before the SLEEP instruction is executed to make the MCU enter the selected Sleep
mode.
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ATtiny212/214/412/414/416
RSTCTRL - Reset Controller
12.
RSTCTRL - Reset Controller
12.1
Features
•
•
•
•
12.2
Returns the Device to an Initial State after a Reset
Identifies the Previous Reset Source
Power Supply Reset Sources:
– Power-on Reset (POR)
– Brown-out Detector (BOD) Reset
User Reset Sources:
– External Reset (RESET)
– Watchdog Timer (WDT) Reset
– Software Reset (SWRST)
– Unified Program and Debug Interface (UPDI) Reset
Overview
The Reset Controller (RSTCTRL) manages the Reset of the device. It issues a device Reset, sets the device to its
initial state, and allows the Reset source to be identified by software.
12.2.1
Block Diagram
Figure 12-1. Reset System Overview
RESET SOURCES
VDD
RESET CONTROLLER
POR
Pull-up
resistor
BOD
UPDI
External Reset
RESET
WDT
All other
peripherals
UPDI
CPU (SW)
12.2.2
Signal Description
Signal
Description
Type
RESET
External Reset (active-low)
Digital input
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ATtiny212/214/412/414/416
RSTCTRL - Reset Controller
12.3
Functional Description
12.3.1
Initialization
The RSTCTRL is always enabled, but some of the Reset sources must be enabled individually (either by Fuses or by
software) before they can request a Reset.
After a Reset from any source, the registers in the device with automatic loading from the Fuses or from the
Signature Row are updated.
12.3.2
Operation
12.3.2.1 Reset Sources
After any Reset, the source that caused the Reset is found in the Reset Flag (RSTCTRL.RSTFR) register. The user
can identify the previous Reset source by reading this register in the software application.
There are two types of Resets based on the source:
• Power Supply Reset Sources:
– Power-on Reset (POR)
– Brown-out Detector (BOD) Reset
• User Reset Sources:
– External Reset (RESET)
– Watchdog Timer (WDT) Reset
– Software Reset (SWRST)
– Unified Program and Debug Interface (UPDI) Reset
12.3.2.1.1 Power-on Reset (POR)
The purpose of the Power-on Reset (POR) is to ensure a safe start-up of logic and memories. It is generated by an
on-chip detection circuit and is always enabled. The POR is activated when the VDD rises and gives active reset as
long as VDD is below the POR threshold voltage (VPOR+). The reset will last until the Start-up and reset initialization
sequence is finished. The Start-up Time (SUT) is determined by fuses. Reset is activated again, without any delay,
when VDD falls below the detection level (VPOR-).
Figure 12-2. MCU Start-Up, RESET Tied to VDD
tSUT
VDD
DEVICE
STATE
tINIT
VPOR-
VPOR+
OFF
Active
Reset
Start-up
Initialization
Running
Active
Reset
INTERNAL
RESET
12.3.2.1.2 Brown-out Detector (BOD) Reset
The on-chip Brown-out Detector (BOD) circuit will monitor the VDD level during operation by comparing it to a fixed
trigger level. The trigger level for the BOD can be selected by fuses. If BOD is unused in the application, it is forced to
a minimum level in order to ensure a safe operation during internal Reset and chip erase.
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ATtiny212/214/412/414/416
RSTCTRL - Reset Controller
Figure 12-3. Brown-out Detector Reset
tBOD
tSUT
tINIT
VBOD+
VDD
VBOD-
DEVICE
STATE
Active
Reset
Running
Initialization
Start-up
Running
INTERNAL
RESET
12.3.2.1.3 External Reset
The external Reset is enabled by a fuse, see the RSTPINCFG field in FUSE.SYSCFG0.
When enabled, the external Reset requests a Reset as long as the RESET pin is low. The device will stay in Reset
until RESET is high again.
Figure 12-4. External Reset Characteristics
tRST
tINIT
VDD
VRST+
RESET
DEVICE
STATE
VRST-
Running
Active
Reset
Initialization
Running
INTERNAL
RESET
12.3.2.1.4 Watchdog Reset
The Watchdog Timer (WDT) is a system function for monitoring correct program operation. If the WDT is not reset
from software according to the programmed time-out period, a Watchdog Reset will be issued. See the WDT Watchdog Timer section for further details.
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ATtiny212/214/412/414/416
RSTCTRL - Reset Controller
Figure 12-5. Watchdog Reset
tWDTR
tINIT
VDD
WDT
TIME-OUT
DEVICE
STATE
Running
Active
Reset
Initialization
Running
INTERNAL
RESET
Note: The time tWDTR is approximately 50 ns.
12.3.2.1.5 Software Reset
The software Reset makes it possible to issue a system Reset from software. The Reset is generated by writing a ‘1’
to the Software Reset Enable (SWRE) bit in the Software Reset (RSTCTRL.SWRR) register.
The Reset will take place immediately after the bit is written, and the device will be kept in Reset until the Reset
sequence is completed.
Figure 12-6. Software Reset
tSWR
tINIT
VDD
SWRST
DEVICE
STATE
Running
Active
Reset
Initialization
Running
INTERNAL
RESET
Note: The time tSWR is approximately 50 ns.
12.3.2.1.6 Unified Program and Debug Interface (UPDI) Reset
The Unified Program and Debug Interface (UPDI) contains a separate Reset source used to reset the device during
external programming and debugging. The Reset source is accessible only from external debuggers and
programmers. More details can be found in the UPDI - Unified Program and Debug Interface section.
12.3.2.1.7 Domains Affected By Reset
The following logic domains are affected by the various Resets:
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ATtiny212/214/412/414/416
RSTCTRL - Reset Controller
Table 12-1. Logic Domains Affected by Various Resets
Reset Type
POR
BOD
Software Reset
External Reset
Watchdog Reset
UPDI Reset
Fuses are
Reloaded
X
X
X
X
X
X
TCD Pin Override
Reset of TCD Pin
Functionality Available Override Settings
X
X
X
X
X
X
Reset of
UPDI
X
X
Reset of Other
Volatile Logic
X
X
X
X
X
X
12.3.2.2 Reset Time
The Reset time can be split into two parts.
The first part is when any of the Reset sources are active. This part depends on the input to the Reset sources. The
external Reset is active as long as the RESET pin is low. The Power-on Reset (POR) and the Brown-out Detector
(BOD) are active as long as the supply voltage is below the Reset source threshold.
The second part is when all the Reset sources are released, and an internal Reset initialization of the device is done.
This time will be increased with the start-up time given by the Start-Up Time Setting (SUT) bit field in the System
Configuration 1 (FUSE.SYSCFG1) fuse when the reset is caused by a Power Supply Reset Source. The internal
Reset initialization time will also increase if the Cyclic Redundancy Check Memory Scan (CRCSCAN) is configured to
run at start-up. This configuration can be changed in the CRC Source (CRCSRC) bit field in the System Configuration
0 (FUSE.SYSCFG0) fuse.
12.3.3
Sleep Mode Operation
The RSTCTRL operates in Active mode and in all sleep modes.
12.3.4
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 12-2. RSTCTRL - Registers Under Configuration Change Protection
Register
Key
RSTCTRL.SWRR
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RSTCTRL - Reset Controller
12.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
RSTFR
SWRR
7:0
7:0
12.5
7
6
5
4
3
2
1
0
UPDIRF
SWRF
WDRF
EXTRF
BORF
PORF
SWRE
Register Description
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RSTCTRL - Reset Controller
12.5.1
Reset Flag Register
Name:
Offset:
Reset:
Property:
RSTFR
0x00
0xXX
-
All flags are cleared by writing a ‘1’ to them. They are also cleared by a Power-on Reset (POR), except for the
Power-on Reset Flag (PORF).
Bit
7
6
Access
Reset
5
UPDIRF
R/W
x
4
SWRF
R/W
x
3
WDRF
R/W
x
2
EXTRF
R/W
x
1
BORF
R/W
x
0
PORF
R/W
x
Bit 5 – UPDIRF UPDI Reset Flag
This bit is set if a UPDI Reset occurs.
Bit 4 – SWRF Software Reset Flag
This bit is set if a Software Reset occurs.
Bit 3 – WDRF Watchdog Reset Flag
This bit is set if a Watchdog Reset occurs.
Bit 2 – EXTRF External Reset Flag
This bit is set if an External Reset occurs.
Bit 1 – BORF Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs.
Bit 0 – PORF Power-on Reset Flag
This bit is set if a POR occurs.
After a POR, only the POR flag is set and all the other flags are cleared. No other flags can be set before a full
system boot is run after the POR.
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RSTCTRL - Reset Controller
12.5.2
Software Reset Register
Name:
Offset:
Reset:
Property:
Bit
7
SWRR
0x01
0x00
Configuration Change Protection
6
5
4
3
Access
Reset
2
1
0
SWRE
R/W
0
Bit 0 – SWRE Software Reset Enable
When this bit is written to ‘1’, a software Reset will occur.
This bit will always read as ‘0’.
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CPUINT - CPU Interrupt Controller
13.
CPUINT - CPU Interrupt Controller
13.1
Features
•
•
•
•
•
•
•
13.2
Short and Predictable Interrupt Response Time
Separate Interrupt Configuration and Vector Address for Each Interrupt
Interrupt Prioritizing by Level and Vector Address
Non-Maskable Interrupts (NMI) for Critical Functions
Two Interrupt Priority Levels: 0 (Normal) and 1 (High):
– One of the interrupt requests can optionally be assigned as a priority level 1 interrupt
– Optional round robin priority scheme for priority level 0 interrupts
Interrupt Vectors Optionally Placed in the Application Section or the Boot Loader Section
Selectable Compact Vector Table (CVT)
Overview
An interrupt request signals a change of state inside a peripheral and can be used to alter the program execution.
The peripherals can have one or more interrupts. All interrupts are individually enabled and configured. When an
interrupt is enabled and configured, it will generate an interrupt request when the interrupt condition occurs.
The CPU Interrupt Controller (CPUINT) handles and prioritizes the interrupt requests. When an interrupt is enabled
and the interrupt condition occurs, the CPUINT will receive the interrupt request. Based on the interrupt's priority level
and the priority level of any ongoing interrupt, the interrupt request is either acknowledged or kept pending until it has
priority. After returning from the interrupt handler, the program execution continues from where it was before the
interrupt occurred, and any pending interrupts are served after one instruction is executed.
The CPUINT offers NMI for critical functions, one selectable high-priority interrupt and an optional round robin
scheduling scheme for normal-priority interrupts. The round robin scheduling ensures that all interrupts are serviced
within a certain amount of time.
13.2.1
Block Diagram
Figure 13-1. CPUINT Block Diagram
Interrupt Controller
Priority
Decoder
Peripheral 1
INT REQ
CPU RETI
CPU INT ACK
CPU
CPU INT REQ
Peripheral n
INT REQ
STATUS
LVL0PRI
LVL1VEC
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CPUINT - CPU Interrupt Controller
13.3
Functional Description
13.3.1
Initialization
An interrupt must be initialized in the following order:
1.
2.
3.
13.3.2
Configure the CPUINT if the default configuration is not adequate (optional):
– Vector handling is configured by writing to the respective bits (IVSEL and CVT) in the Control A
(CPUINT.CTRLA) register.
– Vector prioritizing by round robin is enabled by writing a ‘1’ to the Round Robin Priority Enable (LVL0RR)
bit in CPUINT.CTRLA.
– Select the Priority Level 1 vector by writing the interrupt vector number to the Interrupt Vector with Priority
Level 1 (CPUINT.LVL1VEC) register.
Configure the interrupt conditions within the peripheral and enable the peripheral’s interrupt.
Enable interrupts globally by writing a ‘1’ to the Global Interrupt Enable (I) bit in the CPU Status (CPU.SREG)
register.
Operation
13.3.2.1 Enabling, Disabling and Resetting
The global enabling of interrupts is done by writing a ‘1’ to the Global Interrupt Enable (I) bit in the CPU Status
(CPU.SREG) register. To disable interrupts globally, write a ‘0’ to the I bit in CPU.SREG.
The desired interrupt lines must also be enabled in the respective peripheral by writing to the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
The interrupt flags are not automatically cleared after the interrupt is executed. The respective INTFLAGS register
descriptions provide information on how to clear specific flags.
13.3.2.2 Interrupt Vector Locations
The interrupt vector placement is dependent on the value of the Interrupt Vector Select (IVSEL) bit in the Control A
(CPUINT.CTRLA) register. Refer to the IVSEL description in CPUINT.CTRLA for the possible locations.
If the program never enables an interrupt source, the interrupt vectors are not used, and the regular program code
can be placed at these locations.
13.3.2.3 Interrupt Response Time
The minimum interrupt response time is represented in the following table.
Table 13-1. Minimum Interrupt Response Time
Flash Size > 8 KB
Flash Size ≤ 8 KB
Finish ongoing instruction
One cycle
One cycle
Store PC to stack
Two cycles
Two cycles
Jump to interrupt handler
Three cycles (jmp)
Two cycles (rjmp)
After the Program Counter is pushed on the stack, the program vector for the interrupt is executed. See the following
figure.
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CPUINT - CPU Interrupt Controller
Figure 13-2. Interrupt Execution of Single-Cycle Instruction
Clock
Program Counter
"Instruction"
(1)
INT REQ
INT ACK
If an interrupt occurs during the execution of a multi-cycle instruction, the instruction is completed before the interrupt
is served, as shown in the following figure.
Figure 13-3. Interrupt Execution of Multi-Cycle Instruction
Clock
Program Counter
"Instruction"
(1)
INT REQ
INT ACK
If an interrupt occurs when the device is in a sleep mode, the interrupt execution response time is increased by five
clock cycles, as shown in the figure below. Also, the response time is increased by the start-up time from the selected
sleep mode.
Figure 13-4. Interrupt Execution From Sleep
Clock
Program Counter
(1)
"Instruction"
INT REQ
INT ACK
A return from an interrupt handling routine takes four to five clock cycles, depending on the size of the Program
Counter. During these clock cycles, the Program Counter is popped from the stack, and the Stack Pointer is
incremented.
Note:
1. Devices with 8 KB of Flash or less use RJMP instead of JMP, which takes only two clock cycles.
13.3.2.4 Interrupt Priority
All interrupt vectors are assigned to one of three possible priority levels, as shown in the table below. An interrupt
request from a high-priority source will interrupt any ongoing interrupt handler from a normal-priority source. When
returning from the high-priority interrupt handler, the execution of the normal-priority interrupt handler will resume.
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CPUINT - CPU Interrupt Controller
Table 13-2. Interrupt Priority Levels
Priority
Level
Source
Highest
Non-Maskable Interrupt
Device-dependent and statically assigned
...
Level 1 (high priority)
One vector is optionally user selectable as level 1
Lowest
Level 0 (normal priority)
The remaining interrupt vectors
13.3.2.4.1 Non-Maskable Interrupts
A Non-Maskable Interrupt (NMI) will be executed regardless of the I bit setting in CPU.SREG. An NMI will never
change the I bit. No other interrupt can interrupt an NMI handler. If more than one NMI is requested at the same time,
the priority is static according to the interrupt vector address, where the lowest address has the highest priority.
Which interrupts are non-maskable is device-dependent and not subject to configuration. Non-maskable interrupts
must be enabled before they can be used. Refer to the Interrupt Vector Mapping table of the device for available NMI
sources.
13.3.2.4.2 High-Priority Interrupt
It is possible to assign one interrupt request to level 1 (high priority) by writing its interrupt vector number to the
CPUINT.LVL1VEC register. This interrupt request will have a higher priority than the other (normal priority) interrupt
requests. The priority level 1 interrupts will interrupt the level 0 interrupt handlers.
13.3.2.4.3 Normal-Priority Interrupts
All interrupt vectors other than NMI are assigned to priority level 0 (normal) by default. The user may override this by
assigning one of these vectors as a high-priority vector. The device will have many normal-priority vectors, and some
of these may be pending at the same time. Two different scheduling schemes are available to choose which of the
pending normal-priority interrupts to service first: Static or round robin.
IVEC is the interrupt vector mapping, as listed in the Peripherals and Architecture section. The following sections use
IVEC to explain the scheduling schemes. IVEC0 is the Reset vector, IVEC1 is the NMI vector, and so on. In a vector
table with n+1 elements, the vector with the highest vector number is denoted IVECn. Reset, non-maskable
interrupts, and high-level interrupts are included in the IVEC map, but will always be prioritized over the normalpriority interrupts.
Static Scheduling
If several level 0 interrupt requests are pending at the same time, the one with the highest priority is scheduled for
execution first. The following figure illustrates the default configuration, where the interrupt vector with the lowest
address has the highest priority.
Figure 13-5. Default Static Scheduling
Lowest Address
IVEC 0
Highest Priority
IVEC 1
:
:
:
Highest Address
IVEC n
Lowest Priority
Modified Static Scheduling
The default priority can be changed by writing a vector number to the CPUINT.LVL0PRI register. This vector number
will be assigned the lowest priority. The next interrupt vector in the IVEC will have the highest priority among the LVL0
interrupts, as shown in the following figure.
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CPUINT - CPU Interrupt Controller
Figure 13-6. Static Scheduling when CPUINT.LVL0PRI is Different From Zero
Lowest Address
IVEC 0
RESET
IVEC 1
NMI
:
:
:
IVEC Y
Lowest Priority
IVEC Y+1
Highest Priority
:
:
:
Highest Address
IVEC n
Here, value Y has been written to CPUINT.LVL0PRI, so that interrupt vector Y+1 has the highest priority. Note that, in
this case, the priorities will wrap so that the lowest address no longer has the highest priority. This does not include
RESET and NMI, which will always have the highest priority.
Refer to the interrupt vector mapping of the device for available interrupt requests and their interrupt vector number.
Round Robin Scheduling
The static scheduling may prevent some interrupt requests from being serviced. To avoid this, the CPUINT offers
round robin scheduling for normal-priority (LVL0) interrupts. In the round robin scheduling, the CPUINT.LVL0PRI
register stores the last acknowledged interrupt vector number. This register ensures that the last acknowledged
interrupt vector gets the lowest priority and is automatically updated by the hardware. The following figure illustrates
the priority order after acknowledging IVEC Y and after acknowledging IVEC Y+1.
Figure 13-7. Round Robin Scheduling
IVEC Y was the last acknowledged
interrupt
IVEC Y+1 was the last acknowledged
interrupt
IVEC 0
RESET
IVEC 0
RESET
IVEC 1
NMI
IVEC 1
NMI
:
:
:
:
:
:
IVEC Y
Lowest Priority
IVEC Y
IVEC Y+1
Highest Priority
IVEC Y+1
Lowest Priority
IVEC Y+2
Highest Priority
:
:
:
IVEC n
:
:
:
IVEC n
The round robin scheduling for LVL0 interrupt requests is enabled by writing a ‘1’ to the Round Robin Priority Enable
(LVL0RR) bit in the Control A (CPUINT.CTRLA) register.
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CPUINT - CPU Interrupt Controller
13.3.2.5 Compact Vector Table
The Compact Vector Table (CVT) is a feature to allow writing of compact code by having all level 0 interrupts share
the same interrupt vector number. Thus, the interrupts share the same Interrupt Service Routine (ISR). This reduces
the number of interrupt handlers and thereby frees up memory that can be used for the application code.
When CVT is enabled by writing a ‘1’ to the CVT bit in the Control A (CPUINT.CTRLA) register, the vector table
contains these three interrupt vectors:
1. The non-maskable interrupts (NMI) at vector address 1.
2. The Priority Level 1 (LVL1) interrupt at vector address 2.
3. All priority level 0 (LVL0) interrupts at vector address 3.
This feature is most suitable for devices with limited memory and applications using a small number of interrupt
generators.
13.3.3
Debug Operation
When using a level 1 priority interrupt, it is important to make sure the Interrupt Service Routine is configured
correctly as it may cause the application to be stuck in an interrupt loop with level 1 priority.
By reading the CPUINT STATUS (CPUINT.STATUS) register, it is possible to see if the application has executed the
correct RETI (interrupt return) instruction. The CPUINT.STATUS register contains state information, which ensures
that the CPUINT returns to the correct interrupt level when the RETI instruction is executed at the end of an interrupt
handler. Returning from an interrupt will return the CPUINT to the state it had before entering the interrupt.
13.3.4
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 13-3. CPUINT - Registers under Configuration Change Protection
Register
Key
IVSEL in CPUINT.CTRLA
IOREG
CVT in CPUINT.CTRLA
IOREG
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CPUINT - CPU Interrupt Controller
13.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
CTRLA
STATUS
LVL0PRI
LVL1VEC
7:0
7:0
7:0
7:0
13.5
7
6
5
IVSEL
CVT
4
3
NMIEX
2
1
0
LVL1EX
LVL0RR
LVL0EX
LVL0PRI[7:0]
LVL1VEC[7:0]
Register Description
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CPUINT - CPU Interrupt Controller
13.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLA
0x00
0x00
Configuration Change Protection
6
IVSEL
R/W
0
5
CVT
R/W
0
4
3
2
1
0
LVL0RR
R/W
0
Bit 6 – IVSEL Interrupt Vector Select
This bit is protected by the Configuration Change Protection mechanism.
Value
Description
0
Interrupt vectors are placed after the BOOT section of the Flash(1)
1
Interrupt vectors are placed at the start of the BOOT section of the Flash
Note:
1. When the entire Flash is configured as a BOOT section, this bit will be ignored.
Bit 5 – CVT Compact Vector Table
This bit is protected by the Configuration Change Protection mechanism.
Value
Description
0
Compact Vector Table function is disabled
1
Compact Vector Table function is enabled
Bit 0 – LVL0RR Round Robin Priority Enable
This bit is not protected by the Configuration Change Protection mechanism.
Value
Description
0
Priority is fixed for priority level 0 interrupt requests: The lowest interrupt vector address has the
highest priority.
1
The round robin priority scheme is enabled for priority level 0 interrupt requests
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13.5.2
Status
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
NMIEX
R
0
STATUS
0x01
0x00
-
6
5
4
3
2
1
LVL1EX
R
0
0
LVL0EX
R
0
Bit 7 – NMIEX Non-Maskable Interrupt Executing
This flag is set if a non-maskable interrupt is executing. The flag is cleared when returning (RETI) from the interrupt
handler.
Bit 1 – LVL1EX Level 1 Interrupt Executing
This flag is set when a priority level 1 interrupt is executing, or when the interrupt handler has been interrupted by an
NMI. The flag is cleared when returning (RETI) from the interrupt handler.
Bit 0 – LVL0EX Level 0 Interrupt Executing
This flag is set when a priority level 0 interrupt is executing, or when the interrupt handler has been interrupted by a
priority level 1 interrupt or an NMI. The flag is cleared when returning (RETI) from the interrupt handler.
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13.5.3
Interrupt Priority Level 0
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
LVL0PRI
0x02
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
LVL0PRI[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – LVL0PRI[7:0] Interrupt Priority Level 0
This register is used to modify the priority of the LVL0 interrupts. See the section Normal-Priority Interrupts for more
information.
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13.5.4
Interrupt Vector with Priority Level 1
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
LVL1VEC
0x03
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
LVL1VEC[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – LVL1VEC[7:0] Interrupt Vector with Priority Level 1
This bit field contains the number of the single vector with increased priority level 1 (LVL1). If this bit field has the
value 0x00, no vector has LVL1. Consequently, the LVL1 interrupt is disabled.
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EVSYS - Event System
14.
EVSYS - Event System
14.1
Features
•
•
•
•
•
•
•
•
•
14.2
System for Direct Peripheral-to-Peripheral Signaling
Peripherals Can Directly Produce, Use and React to Peripheral Events
Short Response Time
Up to Four Parallel Asynchronous Event Channels Available
Up to Two Parallel Synchronous Event Channels Available
Channels Can Be Configured to Have One Triggering Peripheral Action and Multiple Peripheral Users
Peripherals Can Directly Trigger and React to Events from Other Peripherals
Events Can Be Sent and/or Received by Most Peripherals, and by Software
Works in Active Mode and Standby Sleep Mode
Overview
The Event System (EVSYS) enables direct peripheral-to-peripheral signaling. It allows a change in one peripheral
(the event generator) to trigger actions in other peripherals (the event users) through event channels, without using
the CPU. It is designed to provide short and predictable response times between peripherals, allowing for
autonomous peripheral control and interaction, and also for the synchronized timing of actions in several peripheral
modules. It is thus a powerful tool for reducing the complexity, size, and the execution time of the software.
A change of the event generator’s state is referred to as an event and usually corresponds to one of the peripheral’s
interrupt conditions. Events can be directly forwarded to other peripherals using the dedicated event routing network.
The routing of each channel is configured in software, including event generation and use.
Only one trigger from an event generator peripheral can be routed on each channel, but multiple channels can use
the same generator source. Multiple peripherals can use events from the same channel.
A channel path can be either asynchronous or synchronous to the main clock. The mode must be selected based on
the requirements of the application.
The Event System can directly connect analog and digital converters, analog comparators, I/O port pins, the real-time
counter, timer/counters, and the configurable custom logic peripheral. Events can also be generated from software
and the peripheral clock.
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EVSYS - Event System
14.2.1
Block Diagram
Figure 14-1. Block Diagram
Sync user x
Sync event channel ”k”
Sync event channel 0
Sync source 0
Sync source 1
Sync user 0
Sync source n
SYNCCH
SYNCSTROBE
..
.
..
.
..
.
Async source m
ASYNCCH
SYNCUSER
Async user y
Async user 0
Async event channel ”l”
Async event channel 0
Async source 0
Async source 1
To sync user
..
.
..
.
ASYNCSTROBE
To async user
ASYNCUSER
Figure 14-2. Example of Event Source, Generator, User and Action
Event Generator
Event User
Timer/Counter
ADC
Compare Match
Over-/Underflow
|
Event
Routing
Network
Error
Channel Sweep
Single
Conversion
Event Action Selection
Event Source
Event Action
Notes:
1. For an overview of peripherals supporting events, refer to the block diagram of the device.
2. For a list of event generators, refer to the Channel n Generator Selection (EVSYS.SYNCCH and
EVSYS.ASYNCCH) registers.
3. For a list of event users, refer to the User Channel n Input Selection (EVSYS.SYNCUSER and
EVSYS.ASYNCUSER) registers.
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EVSYS - Event System
14.2.2
Signal Description
Internal Event Signaling
The event signaling can happen either synchronously or asynchronously to the main clock (CLK_MAIN).
Depending on the underlying event, the event signal can be a pulse with a duration of one clock cycle, or a level
signal (similar to a status flag).
Event Output to Pin
14.2.3
Signal
Type
Description
EVOUT[2:0]
Digital Output
Event Output
System Dependencies
To use this peripheral, other parts of the system must be configured correctly, as described below.
Table 14-1. EVSYS System Dependencies
Dependency
Applicable
Peripheral
Clocks
Yes
CLKCTRL
I/O Lines and Connections
Yes
PORTMUX
Interrupts
No
-
Events
Yes
EVSYS
Debug
Yes
UPDI
14.2.3.1 Clocks
The EVSYS uses the peripheral clock for I/O registers and software events. When correctly set up, the routing
network can also be used in sleep modes without any clock. Software events will not work in sleep modes where the
peripheral clock is halted.
14.2.3.2 I/O Lines
The EVSYS can output three event channels asynchronously on pins. The output signals are called EVOUT[2:0].
1. Configure which event channel (one of SYNCCH[1:0] or ASYNCCH[3:0]) is output on which EVOUTn bit by
writing to EVSYS.ASYNCUSER10, EVSYS.ASYNCUSER9, or EVSYS.ASYNCUSER8, respectively.
2. Optional: Configure the pin properties using the port peripheral.
3. Enable the pin output by writing ‘1’ to the respective EVOUTn bit in the Control A (PORTMUX.CTRLA) register
of the PORTMUX peripheral.
14.3
Functional Description
14.3.1
Initialization
Before enabling events within the device, the event users multiplexer and event channels must be configured.
14.3.2
Operation
14.3.2.1 Event User Multiplexer Setup
The event user multiplexer selects the channel for an event user. Each event user has one dedicated event user
multiplexer. Each multiplexer is connected to the supported event channel outputs and can be configured to select
one of these channels.
Event users, which support asynchronous events, also support synchronous events. There are also event users that
support only synchronous events.
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EVSYS - Event System
The event user multiplexers are configured by writing to the corresponding registers:
• Event users supporting both synchronous and asynchronous events are configured by writing to the respective
asynchronous User Channel Input Selection n (EVSYS.ASYNCUSERn) register
• The users of synchronous-only events are configured by writing to the respective Synchronous User Channel
Input Selection n (EVSYS.SYNCUSERn) register
The default setup of all user multiplexers is OFF.
14.3.2.2 Event System Channel
An event channel can be connected to one of the event generators. Event channels support either asynchronous
generators or synchronous generators.
The source for each asynchronous event channel is configured by writing to the respective Asynchronous Channel n
Input Selection (EVSYS.ASYNCCHn) register.
The source for each synchronous event channel is configured by writing to the respective Synchronous Channel n
Input Selection (EVSYS.SYNCCHn) register.
14.3.2.3 Event Generators
Each event channel can receive the events from several event generators. For details on event generation, refer to
the documentation of the corresponding peripheral.
For each event channel, there are several possible event generators, only one of which can be selected at a time.
The event generator trigger is selected for each channel by writing to the respective channel registers
(EVSYS.ASYNCCHn, EVSYS.SYNCCHn). By default, the channels are not connected to any event generator.
14.3.2.4 Software Event
In a software event, the CPU will “strobe” an event channel by inverting the current value for one system clock cycle.
A software event is triggered on a channel by writing a ‘1’ to the respective Strobe bit in the appropriate Channel
Strobe register:
• Software events on asynchronous channel l are initiated by writing a ‘1’ to the ASYNCSTROBE[l] bit in the
Asynchronous Channel Strobe (EVSYS.ASYNCSTROBE) register
• Software events on synchronous channel k are initiated by writing a ‘1’ to the SYNCSTROBE[k] bit in the
Synchronous Channel Strobe (EVSYS.SYNCSTROBE) register
Software events are no different to those produced by event generator peripherals with respect to event users: When
the bit is written to ‘1’, an event will be generated on the respective channel, and received and processed by the
event user.
14.3.3
Interrupts
Not applicable.
14.3.4
Sleep Mode Operation
When configured, the Event System will work in all sleep modes. One exception is software events that require a
system clock.
14.3.5
Debug Operation
This peripheral is unaffected by entering Debug mode.
14.3.6
Synchronization
Asynchronous events are synchronized and handled by compatible event users. Event user peripherals not
compatible with asynchronous events can only be configured to listen to synchronous event channels.
14.3.7
Configuration Change Protection
Not applicable.
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EVSYS - Event System
14.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
...
0x09
0x0A
0x0B
0x0C
...
0x11
0x12
...
0x1C
0x1D
...
0x21
0x22
0x23
ASYNCSTROBE
SYNCSTROBE
ASYNCCH0
ASYNCCH1
ASYNCCH2
ASYNCCH3
7:0
7:0
7:0
7:0
7:0
7:0
ASYNCSTROBE[7:0]
SYNCSTROBE[7:0]
ASYNCCH[7:0]
ASYNCCH[7:0]
ASYNCCH[7:0]
ASYNCCH[7:0]
7:0
7:0
SYNCCH[7:0]
SYNCCH[7:0]
ASYNCUSER0
7:0
ASYNCUSER[7:0]
ASYNCUSER10
7:0
ASYNCUSER[7:0]
7:0
7:0
SYNCUSER[7:0]
SYNCUSER[7:0]
14.5
7
6
5
4
3
2
1
0
Reserved
SYNCCH0
SYNCCH1
Reserved
Reserved
SYNCUSER0
SYNCUSER1
Register Description
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EVSYS - Event System
14.5.1
Asynchronous Channel Strobe
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
ASYNCSTROBE
0x00
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
ASYNCSTROBE[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – ASYNCSTROBE[7:0] Asynchronous Channel Strobe
If the Strobe register location is written, each event channel will be inverted for one system clock cycle (i.e., a single
event is generated).
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EVSYS - Event System
14.5.2
Synchronous Channel Strobe
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
SYNCSTROBE
0x01
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
SYNCSTROBE[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – SYNCSTROBE[7:0] Synchronous Channel Strobe
If the Strobe register location is written, each event channel will be inverted for one system clock cycle (i.e., a single
event is generated).
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EVSYS - Event System
14.5.3
Asynchronous Channel n Generator Selection
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
ASYNCCHn
0x02 + n*0x01 [n=0..3]
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
ASYNCCH[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – ASYNCCH[7:0] Asynchronous Channel Generator Selection
Value
ASYNCCH0
ASYNCCH1
ASYNCCH2
ASYNCCH3
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
Other
OFF
OFF
OFF
OFF
PORTA_PIN0
PORTA_PIN1
PORTA_PIN2
PORTA_PIN3
PORTA_PIN4
PORTA_PIN5
PORTA_PIN6
PORTA_PIN7
UPDI
-
CCL_LUT0
CCL_LUT1
AC0_OUT
TCD0_CMPBCLR
TCD0_CMPASET
TCD0_CMPBSET
TCD0_PROGEV
RTC_OVF
RTC_CMP
PORTB_PIN0
PORTC_PIN0
PORTB_PIN1
PORTC_PIN1
PORTB_PIN2
PORTC_PIN2
PORTB_PIN3
PORTC_PIN3
PORTB_PIN4
PORTB_PIN5
-
PIT_DIV8192
PIT_DIV4096
PIT_DIV2048
PIT_DIV1024
PIT_DIV512
PIT_DIV256
PIT_DIV128
PIT_DIV64
-
Note: Not all pins of a port are available on devices with low pin counts. Check the Pinout Diagram and/or the I/O
Multiplexing table for details.
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EVSYS - Event System
14.5.4
Synchronous Channel n Generator Selection
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
SYNCCHn
0x0A + n*0x01 [n=0..1]
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
SYNCCH[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – SYNCCH[7:0] Synchronous Channel Generator Selection
Value
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
0x14
Other
SYNCCH0
SYNCCH1
OFF
TCB0
TCA0_OVF_LUNF
TCA0_HUNF
TCA0_CMP0
TCA0_CMP1
TCA0_CMP2
PORTC_PIN0
PORTC_PIN1
PORTC_PIN2
PORTC_PIN3
PORTA_PIN0
PORTA_PIN1
PORTA_PIN2
PORTA_PIN3
PORTA_PIN4
PORTA_PIN5
PORTA_PIN6
PORTA_PIN7
-
PORTB_PIN0
PORTB_PIN1
PORTB_PIN2
PORTB_PIN3
PORTB_PIN4
PORTB_PIN5
-
Note: Not all pins of a port are available on devices with low pin counts. Check the Pinout Diagram and/or the I/O
Multiplexing table for details.
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EVSYS - Event System
14.5.5
Asynchronous User Channel n Input Selection
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
ASYNCUSERn
0x12 + n*0x01 [n=0..10]
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
ASYNCUSER[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – ASYNCUSER[7:0] Asynchronous User Channel Selection
ASYNCUSERn
User Multiplexer
Description
0
1
2
3
4
5
6
7
8
9
10
TCB0
ADC0
CCL_LUT0EV0
CCL_LUT1EV0
CCL_LUT0EV1
CCL_LUT1EV1
TCD0_EV0
TCD0_EV1
EVOUT0
EVOUT1
EVOUT2
Timer/Counter B 0
ADC 0
CCL LUT0 Event 0
CCL LUT1 Event 0
CCL LUT0 Event 1
CCL LUT1 Event 1
Timer Counter D 0 Event 0
Timer Counter D 0 Event 1
Event OUT 0
Event OUT 1
Event OUT 2
Value
Name
0x0
0x1
0x2
0x3
0x4
0x5
0x6
Other
OFF
SYNCCH0
SYNCCH1
ASYNCCH0
ASYNCCH1
ASYNCCH2
ASYNCCH3
-
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EVSYS - Event System
14.5.6
Synchronous User Channel n Input Selection
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
SYNCUSERn
0x22 + n*0x01 [n=0..1]
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
SYNCUSER[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – SYNCUSER[7:0] Synchronous User Channel Selection
SYNCUSERn
User Multiplexer
Description
0
1
TCA0
USART0
Timer/Counter A
USART
Value
Name
0x0
0x1
0x2
Other
OFF
SYNCCH0
SYNCCH1
-
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PORTMUX - Port Multiplexer
15.
PORTMUX - Port Multiplexer
15.1
Overview
The Port Multiplexer (PORTMUX) can either enable or disable the functionality of pins or change between default and
alternative pin positions. This depends on the actual pin and property and is described in detail in the PORTMUX
register map.
For available pins and functionalities, refer to 5. I/O Multiplexing and Considerations.
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PORTMUX - Port Multiplexer
15.2
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
CTRLA
CTRLB
CTRLC
CTRLD
7:0
7:0
7:0
7:0
15.3
7
6
5
4
LUT1
LUT0
TWI0
3
2
1
0
EVOUT1
TCA03
EVOUT2
SPI0
TCA02
EVOUT0
USART0
TCA00
TCB0
TCA01
Register Description
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PORTMUX - Port Multiplexer
15.3.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
0x00
-
6
Access
Reset
5
LUT1
R/W
0
4
LUT0
R/W
0
3
2
EVOUT2
R/W
0
1
EVOUT1
R/W
0
0
EVOUT0
R/W
0
Bit 5 – LUT1 CCL LUT 1 Output
Write this bit to '1' to select the alternative pin location for CCL LUT 1.
Bit 4 – LUT0 CCL LUT 0 Output
Write this bit to '1' to select the alternative pin location for CCL LUT 0.
Bit 2 – EVOUT2 Event Output 2
Write this bit to '1' to enable event output 2.
Bit 1 – EVOUT1 Event Output 1
Write this bit to '1' to enable event output 1.
Bit 0 – EVOUT0 Event Output 0
Write this bit to '1' to enable event output 0.
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PORTMUX - Port Multiplexer
15.3.2
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x01
0x00
-
6
Access
Reset
5
4
TWI0
R/W
0
3
2
SPI0
R/W
0
1
0
USART0
R/W
0
Bit 4 – TWI0 TWI 0 Communication
Write this bit to '1' to select alternative communication pins for TWI 0.
Bit 2 – SPI0 SPI 0 Communication
Write this bit to '1' to select alternative communication pins for SPI 0.
Bit 0 – USART0 USART 0 Communication
Write this bit to '1' to select alternative communication pins for USART 0.
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PORTMUX - Port Multiplexer
15.3.3
Control C
Name:
Offset:
Reset:
Property:
Bit
7
CTRLC
0x02
0x00
-
6
Access
Reset
5
4
3
TCA03
R/W
0
2
TCA02
R/W
0
1
TCA01
R/W
0
0
TCA00
R/W
0
Bit 3 – TCA03 TCA0 Waveform Output 3
Write this bit to '1' to select the alternative output pin for TCA0 waveform output 3 in Split mode.
Not applicable when TCA is in Normal mode.
Bit 2 – TCA02 TCA0 Waveform Output 2
Write this bit to '1' to select the alternative output pin for TCA0 waveform output 2.
In Split Mode, this bit controls output from low byte compare channel 2.
Bit 1 – TCA01 TCA0 Waveform Output 1
Write this bit to '1' to select the alternative output pin for TCA0 waveform output 1.
In Split mode, this bit controls output from low byte compare channel 1.
Bit 0 – TCA00 TCA0 Waveform Output 0
Write this bit to '1' to select the alternative output pin for TCA0 waveform output 0.
In Split mode, this bit controls output from low byte compare channel 0.
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PORTMUX - Port Multiplexer
15.3.4
Control D
Name:
Offset:
Reset:
Property:
Bit
7
CTRLD
0x03
0x00
-
6
5
4
3
2
Access
Reset
1
0
TCB0
R/W
0
Bit 0 – TCB0 TCB0 Output
Write this bit to '1' to select the alternative output pin for 16-bit timer/counter B 0.
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PORT - I/O Pin Configuration
16.
PORT - I/O Pin Configuration
16.1
Features
•
•
•
•
16.2
General Purpose Input and Output Pins with Individual Configuration:
– Pull-up
– Inverted I/O
Interrupts and Events:
– Sense both edges
– Sense rising edges
– Sense falling edges
– Sense low level
Asynchronous Pin Change Sensing that Can Wake the Device From all Sleep Modes
Efficient and Safe Access to Port Pins
– Hardware Read-Modify-Write (RMW) through dedicated toggle/clear/set registers
– Mapping of often-used PORT registers into bit-accessible I/O memory space (virtual ports)
Overview
The I/O pins of the device are controlled by instances of the PORT peripheral registers. Each PORT instance has up
to eight I/O pins. The PORTs are named PORTA, PORTB, PORTC, etc. Refer to the I/O Multiplexing and
Considerations section to see which pins are controlled by what instance of PORT. The base addresses of the PORT
instances and the corresponding Virtual PORT instances are listed in the Peripherals and Architecture section.
Each PORT pin has a corresponding bit in the Data Direction (PORTx.DIR) and Data Output Value (PORTx.OUT)
registers to enable that pin as an output and to define the output state. For example, pin PA3 is controlled by DIR[3]
and OUT[3] of the PORTA instance.
The input value of a PORT pin is synchronized to the Peripheral Clock (CLK_PER) and then made accessible as the
data input value (PORTx.IN). The value of the pin can be read whether the pin is configured as input or output.
The PORT also supports asynchronous input sensing with interrupts and events for selectable pin change conditions.
Asynchronous pin change sensing means that a pin change can trigger an interrupt and wake the device from sleep,
including sleep modes where CLK_PER is stopped.
All pin functions are individually configurable per pin. The pins have hardware Read-Modify-Write functionality for a
safe and correct change of the drive values and/or input and sense configuration.
The PORT pin configuration controls input and output selection of other device functions.
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PORT - I/O Pin Configuration
16.2.1
Block Diagram
Figure 16-1. PORT Block Diagram
Pull-up Enable
DIRn
Q
D
Peripheral Override
R
OUTn
Q
D
Pxn
Peripheral Override
R
Invert Enable
Synchronizer
INn
Synchronous
Input
Q
D Q
R
D
R
Sense Configuration
Interrupt
Generator
Interrupt
Asynchronous
Input/Event
Input Disable
Peripheral Override
Analog
Input/Output
16.2.2
Signal Description
Signal
Type
Description
Pxn
I/O pin
I/O pin n on PORTx
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PORT - I/O Pin Configuration
16.3
Functional Description
16.3.1
Initialization
After Reset, all outputs are tri-stated, and digital input buffers enabled even if there is no clock running.
The following steps are all optional when initializing PORT operation:
•
•
•
•
Enable or disable the output driver for pin Pxn by respectively writing ‘1’ to bit n in the PORTx.DIRSET or
PORTx.DIRCLR register
Set the output driver for pin Pxn to high or low level respectively by writing ‘1’ to bit n in the PORTx.OUTSET or
PORTx.OUTCLR register
Read the input of pin Pxn by reading bit n in the PORTx.IN register
Configure the individual pin configurations and interrupt control for pin Pxn in PORTx.PINnCTRL
Important: For lowest power consumption, disable the digital input buffer of unused pins and pins that
are used as analog inputs or outputs.
Specific pins, such as those used to connect a debugger, may be configured differently, as required by their special
function.
16.3.2
Operation
16.3.2.1 Basic Functions
Each pin group x has its own set of PORT registers. I/O pin Pxn can be controlled by the registers in PORTx.
To use pin number n as an output, write bit n of the PORTx.DIR register to ‘1’. This can be done by writing bit n in the
PORTx.DIRSET register to ‘1’, which will avoid disturbing the configuration of other pins in that group. The nth bit in
the PORTx.OUT register must be written to the desired output value.
Similarly, writing a PORTx.OUTSET bit to ‘1’ will set the corresponding bit in the PORTx.OUT register to ‘1’. Writing a
bit in PORTx.OUTCLR to ‘1’ will clear that bit in PORTx.OUT to ‘0’. Writing a bit in PORTx.OUTTGL or PORTx.IN to
‘1’ will toggle that bit in PORTx.OUT.
To use pin n as an input, bit n in the PORTx.DIR register must be written to ‘0’ to disable the output driver. This can
be done by writing bit n in the PORTx.DIRCLR register to ‘1’, which will avoid disturbing the configuration of other
pins in that group. The input value can be read from bit n in the PORTx.IN register as long as the ISC bit is not set to
INPUT_DISABLE.
Writing a bit to ‘1’ in PORTx.DIRTGL will toggle that bit in PORTx.DIR and toggle the direction of the corresponding
pin.
16.3.2.2 Pin Configuration
The Pin n Control (PORTx.PINnCTRL) register is used to configure inverted I/O, pull-up, and input sensing of a pin.
The control register for pin n is at the byte address PORTx + 0x10 + �.
All input and output on the respective pin n can be inverted by writing a ‘1’ to the Inverted I/O Enable (INVEN) bit in
PORTx.PINnCTRL. When INVEN is ‘1’, the PORTx.IN/OUT/OUTSET/OUTTGL registers will have an inverted
operation for this pin.
Toggling the INVEN bit causes an edge on the pin, which can be detected by all peripherals using this pin, and is
seen by interrupts or events if enabled.
The input pull-up of pin n is enabled by writing a ‘1’ to the Pull-up Enable (PULLUPEN) bit in PORTx.PINnCTRL. The
pull-up is disconnected when the pin is configured as an output, even if PULLUPEN is ‘1’.
Pin interrupts can be enabled for pin n by writing to the Input/Sense Configuration (ISC) bit field in
PORTx.PINnCTRL. Refer to 16.3.3 Interrupts for further details.
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PORT - I/O Pin Configuration
The digital input buffer for pin n can be disabled by writing the INPUT_DISABLE setting to ISC. This can reduce
power consumption and may reduce noise if the pin is used as analog input. While configured to INPUT_DISABLE,
bit n in PORTx.IN will not change since the input synchronizer is disabled.
16.3.2.3 Virtual Ports
The Virtual PORT registers map the most frequently used regular PORT registers into the I/O Register space with
single-cycle bit access. Access to the Virtual PORT registers has the same outcome as access to the regular
registers but allows for memory specific instructions, such as bit manipulation instructions, which cannot be used in
the extended I/O Register space where the regular PORT registers reside. The following table shows the mapping
between the PORT and VPORT registers.
Table 16-1. Virtual Port Mapping
Regular PORT Register
Mapped to Virtual PORT Register
PORTx.DIR
VPORTx.DIR
PORTx.OUT
VPORTx.OUT
PORTx.IN
VPORTx.IN
PORTx.INTFLAGS
VPORTx.INTFLAGS
16.3.2.4 Peripheral Override
Peripherals such as USARTs, ADCs and timers may be connected to I/O pins. Such peripherals will usually have a
primary and, optionally, one or more alternate I/O pin connections, selectable by PORTMUX or a multiplexer inside
the peripheral. By configuring and enabling such peripherals, the general purpose I/O pin behavior normally
controlled by PORT will be overridden in a peripheral dependent way. Some peripherals may not override all the
PORT registers, leaving the PORT module to control some aspects of the I/O pin operation.
Refer to the description of each peripheral for information on the peripheral override. Any pin in a PORT that is not
overridden by a peripheral will continue to operate as a general purpose I/O pin.
16.3.3
Interrupts
Table 16-2. Available Interrupt Vectors and Sources
Name
Vector Description Conditions
PORTx PORT interrupt
INTn in PORTx.INTFLAGS is raised as configured by the Input/Sense Configuration
(ISC) bit in PORTx.PINnCTRL
Each PORT pin n can be configured as an interrupt source. Each interrupt can be individually enabled or disabled by
writing to ISC in PORTx.PINnCTRL.
When an interrupt condition occurs, the corresponding interrupt flag is set in the Interrupt Flags register of the
peripheral (peripheral.INTFLAGS).
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral's INTFLAGS register for
details on how to clear interrupt flags.
When setting or changing interrupt settings, take these points into account:
• If an Inverted I/O Enable (INVEN) bit is toggled in the same cycle as ISC is changed, the edge caused by the
inversion toggling may not cause an interrupt request
• If an input is disabled by writing to ISC while synchronizing an interrupt, that interrupt may be requested on reenabling the input, even if it is re-enabled with a different interrupt setting
• If the interrupt setting is changed by writing to ISC while synchronizing an interrupt, that interrupt may not be
requested
16.3.3.1 Asynchronous Sensing Pin Properties
All PORT pins support asynchronous input sensing with interrupts for selectable pin change conditions. Fully
asynchronous pin change sensing can trigger an interrupt and wake the device from all sleep modes, including
modes where the Peripheral Clock (CLK_PER) is stopped, while partially asynchronous pin change sensing is limited
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PORT - I/O Pin Configuration
as per the table below. See the I/O Multiplexing and Considerations section for further details on which pins support
fully asynchronous pin change sensing.
Table 16-3. Behavior Comparison of Sense Pins
Property
Partially Asynchronous Pins
Waking the device from sleep
modes with CLK_PER running
From all interrupt sense configurations
Waking the device from sleep
modes with CLK_PER stopped
Only from BOTHEDGES or LEVEL
interrupt sense configurations
Minimum pulse-width to trigger an
interrupt with CLK_PER running
Minimum one CLK_PER cycle
Minimum pulse-width to trigger an
interrupt with CLK_PER stopped
The pin value must be kept until
CLK_PER has restarted(1)
Interrupt “dead-time”
No new interrupt for three CLK_PER
cycles after the previous
Fully Asynchronous Pins
From all interrupt sense
configurations
Less than one CLK_PER cycle
Note:
1. If a partially asynchronous input pin is used for wake-up from sleep with CLK_PER stopped, the required level
must be held long enough for the MCU to complete the wake-up to trigger the interrupt. If the level disappears,
the MCU can wake up without any interrupt generated.
16.3.4
Events
PORT can generate the following events:
Table 16-4. Event Generators in PORTx
Generator Name
Peripheral
Event
PORTx
PINn
Description
Event Type
Generating Clock Domain
Length of Event
Pin level
Level
Asynchronous
Given by pin level
All PORT pins are asynchronous event system generators. PORT has as many event generators as there are PORT
pins in the device. Each event system output from PORT is the value present on the corresponding pin if the digital
input buffer is enabled. If a pin input buffer is disabled, the corresponding event system output is zero.
PORT has no event inputs. Refer to the Event System (EVSYS) section for more details regarding event types and
Event System configuration.
16.3.5
Sleep Mode Operation
Except for interrupts and input synchronization, all pin configurations are independent of sleep modes. All pins can
wake the device from sleep, see the PORT Interrupt section for further details.
Peripherals connected to the PORTs can be affected by sleep modes, described in the respective peripherals’ data
sheet section.
Important: The PORTs will always use the Peripheral Clock (CLK_PER). Input synchronization will halt
when this clock stops.
16.3.6
Debug Operation
When the CPU is halted in Debug mode, the PORT continues normal operation. If the PORT is configured in a way
that requires it to be periodically serviced by the CPU through interrupts or similar, improper operation or data loss
may result during debugging.
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PORT - I/O Pin Configuration
16.4
Register Summary - PORTx
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
...
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
DIR
DIRSET
DIRCLR
DIRTGL
OUT
OUTSET
OUTCLR
OUTTGL
IN
INTFLAGS
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
16.5
7
6
5
4
3
2
1
0
DIR[7:0]
DIRSET[7:0]
DIRCLR[7:0]
DIRTGL[7:0]
OUT[7:0]
OUTSET[7:0]
OUTCLR[7:0]
OUTTGL[7:0]
IN[7:0]
INT[7:0]
Reserved
PIN0CTRL
PIN1CTRL
PIN2CTRL
PIN3CTRL
PIN4CTRL
PIN5CTRL
PIN6CTRL
PIN7CTRL
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
INVEN
INVEN
INVEN
INVEN
INVEN
INVEN
INVEN
INVEN
PULLUPEN
PULLUPEN
PULLUPEN
PULLUPEN
PULLUPEN
PULLUPEN
PULLUPEN
PULLUPEN
ISC[2:0]
ISC[2:0]
ISC[2:0]
ISC[2:0]
ISC[2:0]
ISC[2:0]
ISC[2:0]
ISC[2:0]
Register Description - PORTx
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PORT - I/O Pin Configuration
16.5.1
Data Direction
Name:
Offset:
Reset:
Property:
Bit
7
DIR
0x00
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DIR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DIR[7:0] Data Direction
This bit field controls the output driver for each PORTx pin.
This bit field does not control the digital input buffer. The digital input buffer for pin n (Pxn) can be configured in the
Input/Sense Configuration (ISC) bit field in the Pin n Control (PORTx.PINnCTRL) register.
The available configuration for each bit n in this bit field is shown in the table below.
Value
Description
0
Pxn is configured as an input-only pin, and the output driver is disabled
1
Pxn is configured as an output pin, and the output driver is enabled
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PORT - I/O Pin Configuration
16.5.2
Data Direction Set
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
DIRSET
0x01
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
DIRSET[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DIRSET[7:0] Data Direction Set
This bit field controls the output driver for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will set the corresponding bit in PORTx.DIR, which will configure pin n (Pxn) as an
output pin and enable the output driver.
Reading this bit field will return the value of PORTx.DIR.
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PORT - I/O Pin Configuration
16.5.3
Data Direction Clear
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
DIRCLR
0x02
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
DIRCLR[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DIRCLR[7:0] Data Direction Clear
This bit field controls the output driver for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will clear the corresponding bit in PORTx.DIR, which will configure pin n (Pxn) as
an input-only pin and disable the output driver.
Reading this bit field will return the value of PORTx.DIR.
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PORT - I/O Pin Configuration
16.5.4
Data Direction Toggle
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
DIRTGL
0x03
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
DIRTGL[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DIRTGL[7:0] Data Direction Toggle
This bit field controls the output driver for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will toggle the corresponding bit in PORTx.DIR.
Reading this bit field will return the value of PORTx.DIR.
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PORT - I/O Pin Configuration
16.5.5
Output Value
Name:
Offset:
Reset:
Property:
Bit
7
OUT
0x04
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
OUT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – OUT[7:0] Output Value
This bit field controls the output driver level for each PORTx pin.
This configuration only has an effect when the output driver (PORTx.DIR) is enabled for the corresponding pin.
The available configuration for each bit n in this bit field is shown in the table below.
Value
Description
0
The pin n (Pxn) output is driven low
1
The Pxn output is driven high
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PORT - I/O Pin Configuration
16.5.6
Output Value Set
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
OUTSET
0x05
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
OUTSET[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – OUTSET[7:0] Output Value Set
This bit field controls the output driver level for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will set the corresponding bit in PORTx.OUT, which will configure the output for pin
n (Pxn) to be driven high.
Reading this bit field will return the value of PORTx.OUT.
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PORT - I/O Pin Configuration
16.5.7
Output Value Clear
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
OUTCLR
0x06
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
OUTCLR[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – OUTCLR[7:0] Output Value Clear
This bit field controls the output driver level for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will clear the corresponding bit in PORTx.OUT, which will configure the output for
pin n (Pxn) to be driven low.
Reading this bit field will return the value of PORTx.OUT.
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PORT - I/O Pin Configuration
16.5.8
Output Value Toggle
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
OUTTGL
0x07
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
OUTTGL[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – OUTTGL[7:0] Output Value Toggle
This bit field controls the output driver level for each PORTx pin, without using a read-modify-write operation.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will toggle the corresponding bit in PORTx.OUT.
Reading this bit field will return the value of PORTx.OUT.
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PORT - I/O Pin Configuration
16.5.9
Input Value
Name:
Offset:
Reset:
Property:
Bit
7
IN
0x08
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
IN[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – IN[7:0] Input Value
This bit field shows the state of the PORTx pins when the digital input buffer is enabled.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will toggle the corresponding bit in PORTx.OUT.
If the digital input buffer is disabled, the input is not sampled, and the bit value will not change. The digital input buffer
for pin n (Pxn) can be configured in the Input/Sense Configuration (ISC) bit field in the Pin n Control
(PORTx.PINnCTRL) register.
The available states of each bit n in this bit field is shown in the table below.
Value
Description
0
The voltage level on Pxn is low
1
The voltage level on Pxn is high
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PORT - I/O Pin Configuration
16.5.10 Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x09
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
INT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – INT[7:0] Pin Interrupt Flag
Pin interrupt flag n is cleared by writing a ‘1’ to it.
Pin interrupt flag n is set when the change or state of pin n (Pxn) matches the pin's Input/Sense Configuration (ISC)
in PORTx.PINnCTRL.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will clear Pin interrupt flag n.
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PORT - I/O Pin Configuration
16.5.11 Pin n Control
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
INVEN
R/W
0
PINnCTRL
0x10 + n*0x01 [n=0..7]
0x00
-
6
5
4
3
PULLUPEN
R/W
0
2
R/W
0
1
ISC[2:0]
R/W
0
0
R/W
0
Bit 7 – INVEN Inverted I/O Enable
This bit controls whether the input and output for pin n are inverted or not.
Value
Description
0
Input and output values are not inverted
1
Input and output values are inverted
Bit 3 – PULLUPEN Pull-up Enable
This bit controls whether the internal pull-up of pin n is enabled or not when the pin is configured as input-only.
Value
Description
0
Pull-up disabled
1
Pull-up enabled
Bits 2:0 – ISC[2:0] Input/Sense Configuration
This bit field controls the input and sense configuration of pin n. The sense configuration determines how a port
interrupt can be triggered.
Value
Name
Description
0x0
INTDISABLE
Interrupt disabled but input buffer enabled
0x1
BOTHEDGES
Interrupt enabled with sense on both edges
0x2
RISING
Interrupt enabled with sense on rising edge
0x3
FALLING
Interrupt enabled with sense on falling edge
0x4
INPUT_DISABLE
Interrupt and digital input buffer disabled(1)
0x5
LEVEL
Interrupt enabled with sense on low level
other
—
Reserved
Note:
1. If the digital input buffer for pin n is disabled, bit n in the Input Value (PORTx.IN) register will not be updated.
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PORT - I/O Pin Configuration
16.6
Register Summary - VPORTx
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
DIR
OUT
IN
INTFLAGS
7:0
7:0
7:0
7:0
16.7
7
6
5
4
3
2
1
0
DIR[7:0]
OUT[7:0]
IN[7:0]
INT[7:0]
Register Description - VPORTx
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16.7.1
Data Direction
Name:
Offset:
Reset:
Property:
DIR
0x00
0x00
-
Access to the Virtual PORT registers has the same outcome as access to the regular registers but allows for memory
specific instructions, such as bit manipulation instructions, which cannot be used in the extended I/O Register space
where the regular PORT registers reside.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DIR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DIR[7:0] Data Direction
This bit field controls the output driver for each PORTx pin.
This bit field does not control the digital input buffer. The digital input buffer for pin n (Pxn) can be configured in the
Input/Sense Configuration (ISC) bit field in the Pin n Control (PORTx.PINnCTRL) register.
The available configuration for each bit n in this bit field is shown in the table below.
Value
Description
0
Pxn is configured as an input-only pin, and the output driver is disabled
1
Pxn is configured as an output pin, and the output driver is enabled
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16.7.2
Output Value
Name:
Offset:
Reset:
Property:
OUT
0x01
0x00
-
Access to the Virtual PORT registers has the same outcome as access to the regular registers but allows for memory
specific instructions, such as bit manipulation instructions, which cannot be used in the extended I/O Register space
where the regular PORT registers reside.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
OUT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – OUT[7:0] Output Value
This bit field controls the output driver level for each PORTx pin.
This configuration only has an effect when the output driver (PORTx.DIR) is enabled for the corresponding pin.
The available configuration for each bit n in this bit field is shown in the table below.
Value
Description
0
The pin n (Pxn) output is driven low
1
The Pxn output is driven high
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PORT - I/O Pin Configuration
16.7.3
Input Value
Name:
Offset:
Reset:
Property:
IN
0x02
0x00
-
Access to the Virtual PORT registers has the same outcome as access to the regular registers but allows for memory
specific instructions, such as bit manipulation instructions, which cannot be used in the extended I/O Register space
where the regular PORT registers reside.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
IN[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – IN[7:0] Input Value
This bit field shows the state of the PORTx pins when the digital input buffer is enabled.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will toggle the corresponding bit in PORTx.OUT.
If the digital input buffer is disabled, the input is not sampled, and the bit value will not change. The digital input buffer
for pin n (Pxn) can be configured in the Input/Sense Configuration (ISC) bit field in the Pin n Control
(PORTx.PINnCTRL) register.
The available states of each bit n in this bit field is shown in the table below.
Value
Description
0
The voltage level on Pxn is low
1
The voltage level on Pxn is high
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16.7.4
Interrupt Flags
Name:
Offset:
Reset:
Property:
INTFLAGS
0x03
0x00
-
Access to the Virtual PORT registers has the same outcome as access to the regular registers but allows for memory
specific instructions, such as bit manipulation instructions, which cannot be used in the extended I/O Register space
where the regular PORT registers reside.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
INT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – INT[7:0] Pin Interrupt Flag
Pin interrupt flag n is cleared by writing a ‘1’ to it.
Pin interrupt flag n is set when the change or state of pin n (Pxn) matches the pin's Input/Sense Configuration (ISC)
in PORTx.PINnCTRL.
Writing a ‘0’ to bit n in this bit field has no effect.
Writing a ‘1’ to bit n in this bit field will clear Pin interrupt flag n.
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BOD - Brown-out Detector
17.
BOD - Brown-out Detector
17.1
Features
•
•
•
•
•
17.2
Brown-out Detector Monitors the Power Supply to Avoid Operation Below a Programmable Level
Three Available Modes:
– Enabled mode (continuously active)
– Sampled mode
– Disabled
Separate Selection of Mode for Active and Sleep Modes
Voltage Level Monitor (VLM) with Interrupt
Programmable VLM Level Relative to the BOD Level
Overview
The Brown-out Detector (BOD) monitors the power supply and compares the supply voltage with the programmable
brown-out threshold level. The brown-out threshold level defines when to generate a System Reset. The Voltage
Level Monitor (VLM) monitors the power supply and compares it to a threshold higher than the BOD threshold. The
VLM can then generate an interrupt as an “early warning” when the supply voltage is approaching the BOD threshold.
The VLM threshold level is expressed as a percentage above the BOD threshold level.
The BOD is controlled mainly by fuses and has to be enabled by the user. The mode used in Standby sleep mode
and Power-Down sleep mode can be altered in normal program execution. The VLM is controlled by I/O registers as
well.
When activated, the BOD can operate in Enabled mode, where the BOD is continuously active, or in Sampled mode,
where the BOD is activated briefly at a given period to check the supply voltage level.
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BOD - Brown-out Detector
17.2.1
Block Diagram
Figure 17-1. BOD Block Diagram
VDD
BOD
+
BOD
Reset
-
BOD Threshold
VLM
+
VLM
Interrupt
-
VLM Threshold
17.3
Functional Description
17.3.1
Initialization
The BOD settings are loaded from fuses during Reset. The BOD level and operating mode in Active and Idle sleep
mode are set by fuses and cannot be changed by software. The operating mode in Standby and Power-Down sleep
mode is loaded from fuses and can be changed by software.
The Voltage Level Monitor function can be enabled by writing a ‘1’ to the VLM Interrupt Enable (VLMIE) bit in the
Interrupt Control (BOD.INTCTRL) register. The VLM interrupt is configured by writing the VLM Configuration
(VLMCFG) bits in BOD.INTCTRL. An interrupt is requested when the supply voltage crosses the VLM threshold
either from above, below, or any direction.
The VLM functionality will follow the BOD mode. If the BOD is disabled, the VLM will not be enabled, even if the
VLMIE is ‘1’. If the BOD is using Sampled mode, the VLM will also be sampled. When the VLM interrupt is enabled,
the interrupt flag will be set according to VLMCFG when the voltage level is crossing the VLM level.
The VLM threshold is defined by writing the VLM Level (VLMLVL) bits in the Control A (BOD.VLMCTRLA) register.
17.3.2
Interrupts
Table 17-1. Available Interrupt Vectors and Sources
Name Vector Description
VLM
Conditions
Voltage Level Monitor Supply voltage crossing the VLM threshold as configured by the VLM Configuration
(VLMCFG) bit field in the Interrupt Control (BOD.INTCTRL) register
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BOD - Brown-out Detector
The VLM interrupt will not be executed if the CPU is halted in Debug mode.
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
17.3.3
Sleep Mode Operation
The BOD configuration in the different sleep modes is defined by fuses. The mode used in Active mode and Idle
sleep mode is defined by the ACTIVE fuses in FUSE.BODCFG, which is loaded into the ACTIVE bit field in the
Control A (BOD.CTRLA) register. The mode used in Standby sleep mode and Power-Down sleep mode is defined by
SLEEP in FUSE.BODCFG, which is loaded into the SLEEP bit field in the Control A (BOD.CTRLA) register.
The operating mode in Active mode and Idle sleep mode (i.e., ACTIVE in BOD.CTRLA) cannot be altered by
software. The operating mode in Standby sleep mode and Power-Down sleep mode can be altered by writing to the
SLEEP bit field in the Control A (BOD.CTRLA) register.
When the device is going into Standby or Power-Down sleep mode, the BOD will change the operation mode as
defined by SLEEP in BOD.CTRLA. When the device is waking up from Standby or Power-Down sleep mode, the
BOD will operate in the mode defined by the ACTIVE bit field in the Control A (BOD.CTRLA) register.
17.3.4
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 17-2. Registers Under Configuration Change Protection
Register
Key
SLEEP in BOD.CTRLA
IOREG
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BOD - Brown-out Detector
17.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
...
0x07
0x08
0x09
0x0A
0x0B
CTRLA
CTRLB
7:0
7:0
17.5
7
6
5
4
SAMPFREQ
3
2
ACTIVE[1:0]
1
0
SLEEP[1:0]
LVL[2:0]
Reserved
VLMCTRLA
INTCTRL
INTFLAGS
STATUS
7:0
7:0
7:0
7:0
VLMCFG[1:0]
VLMLVL[1:0]
VLMIE
VLMIF
VLMS
Register Description
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ATtiny212/214/412/414/416
BOD - Brown-out Detector
17.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
Loaded from fuse
Configuration Change Protection
6
Access
Reset
5
4
SAMPFREQ
R
x
3
2
1
0
ACTIVE[1:0]
R
x
SLEEP[1:0]
R
x
R/W
x
R/W
x
Bit 4 – SAMPFREQ Sample Frequency
This bit controls the BOD sample frequency.
The Reset value is loaded from the SAMPFREQ bit in FUSE.BODCFG.
This bit is not under Configuration Change Protection (CCP).
Value
Description
0x0
Sample frequency is 1 kHz
0x1
Sample frequency is 125 Hz
Bits 3:2 – ACTIVE[1:0] Active
These bits select the BOD operation mode when the device is in Active or Idle mode.
The Reset value is loaded from the ACTIVE bit field in FUSE.BODCFG.
This bit field is not under Configuration Change Protection (CCP).
Value
Name
Description
0x0
DIS
Disabled
0x1
ENABLED Enabled in continuous mode
0x2
SAMPLED Enabled in sampled mode
0x3
ENWAKE
Enabled in continuous mode. Execution is halted at wake-up until BOD is running
Bits 1:0 – SLEEP[1:0] Sleep
These bits select the BOD operation mode when the device is in Standby or Power-Down sleep mode. The Reset
value is loaded from the SLEEP bit field in FUSE.BODCFG.
Value
Name
Description
0x0
DIS
Disabled
0x1
ENABLED
Enabled in continuous mode
0x2
SAMPLED
Enabled in sampled mode
0x3
Reserved
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BOD - Brown-out Detector
17.5.2
Control B
Name:
Offset:
Reset:
Property:
CTRLB
0x01
Loaded from fuse
-
Bit
7
6
5
4
3
2
Access
Reset
R
0
R
0
R
0
R
0
R
0
R
x
1
LVL[2:0]
R
x
0
R
x
Bits 2:0 – LVL[2:0] BOD Level
This bit field controls the BOD threshold level.
The Reset value is loaded from the BOD Level (LVL) bits in the BOD Configuration Fuse (FUSE.BODCFG).
Value
Name
Description
0x0
BODLEVEL0
1.8V
0x2
BODLEVEL2
2.6V
0x7
BODLEVEL7
4.2V
Notes:
• Refer to the BOD and POR Characteristics in Electrical Characteristics for further details
• Values in the description are typical values
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ATtiny212/214/412/414/416
BOD - Brown-out Detector
17.5.3
VLM Control A
Name:
Offset:
Reset:
Property:
Bit
7
VLMCTRLA
0x08
0x00
-
6
5
4
3
2
Access
Reset
1
0
VLMLVL[1:0]
R/W
R/W
0
0
Bits 1:0 – VLMLVL[1:0] VLM Level
These bits select the VLM threshold relative to the BOD threshold (LVL in BOD.CTRLB).
Value
Description
0x0
VLM threshold 5% above BOD threshold
0x1
VLM threshold 15% above BOD threshold
0x2
VLM threshold 25% above BOD threshold
other
Reserved
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ATtiny212/214/412/414/416
BOD - Brown-out Detector
17.5.4
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x09
0x00
-
6
5
4
3
Access
Reset
2
1
VLMCFG[1:0]
R/W
R/W
0
0
0
VLMIE
R/W
0
Bits 2:1 – VLMCFG[1:0] VLM Configuration
These bits select which incidents will trigger a VLM interrupt.
Value
Name
Description
0x0
BELOW
VDD falls below VLM threshold
0x1
ABOVE
VDD rises above VLM threshold
0x2
CROSS
VDD crosses VLM threshold
Other
Reserved
Bit 0 – VLMIE VLM Interrupt Enable
Writing a ‘1’ to this bit enables the VLM interrupt.
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ATtiny212/214/412/414/416
BOD - Brown-out Detector
17.5.5
VLM Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x0A
0x00
-
6
5
4
3
Access
Reset
2
1
0
VLMIF
R/W
0
Bit 0 – VLMIF VLM Interrupt Flag
This flag is set when a trigger from the VLM is given, as configured by the VLMCFG bit in the BOD.INTCTRL register.
The flag is only updated when the BOD is enabled.
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ATtiny212/214/412/414/416
BOD - Brown-out Detector
17.5.6
VLM Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x0B
0x00
-
6
5
4
3
Access
Reset
2
1
0
VLMS
R
0
Bit 0 – VLMS VLM Status
This bit is only valid when the BOD is enabled.
Value
Description
0
The voltage is above the VLM threshold level
1
The voltage is below the VLM threshold level
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ATtiny212/214/412/414/416
VREF - Voltage Reference
18.
VREF - Voltage Reference
18.1
Features
•
•
18.2
Programmable Voltage Reference Sources:
– One for each ADC peripheral
– One for each AC and DAC peripheral
Each Reference Source Supports Five Different Voltages:
– 0.55V
– 1.1V
– 1.5V
– 2.5V
– 4.3V
Overview
The Voltage Reference (VREF) peripheral provides control registers for the voltage reference sources used by
several peripherals. The user can select the reference voltages for the ADC0 by writing to the ADC0 Reference
Select (ADC0REFSEL) bit field in the Control A (VREF.CTRLA) register, and for both AC0 and DAC0 by writing to the
DAC0 Reference Select (DAC0REFSEL) bit field in the Control A (VREF.CTRLA) register.
A voltage reference source is automatically enabled when requested by a peripheral. The user can enable the
reference voltage sources (and thus, override the automatic disabling of unused sources) by writing to the respective
Force Enable (ADC0REFEN, DAC0REFEN) bit in the Control B (VREF.CTRLB) register. This may be done to
decrease start-up time, at the cost of increased power consumption.
18.2.1
Block Diagram
Figure 18-1. VREF Block Diagram
Reference reque st
Reference enable
Reference se lect
Band gap
Band gap
ena ble
18.3
Functional Description
18.3.1
Initialization
Reference
Gen erator
0.55V
1.1V
1.5V
2.5V
4.3V
BUF
Inte rnal
Reference
The default configuration will enable the respective source when the ADC0, AC0, or DAC0 is requesting a reference
voltage. The default reference voltages are 0.55V but can be configured by writing to the respective Reference Select
(ADC0REFSEL, DAC0REFSEL) bit field in the Control A (VREF.CTRLA) register.
© 2020 Microchip Technology Inc.
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ATtiny212/214/412/414/416
VREF - Voltage Reference
18.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
CTRLA
CTRLB
7:0
7:0
18.5
7
6
5
4
ADC0REFSEL[2:0]
3
2
1
0
DAC0REFSEL[2:0]
ADC0REFEN DAC0REFEN
Register Description
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DS40002287A-page 168
ATtiny212/214/412/414/416
VREF - Voltage Reference
18.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLA
0x00
0x00
-
6
R/W
0
5
ADC0REFSEL[2:0]
R/W
0
4
3
R/W
0
2
R/W
0
1
DAC0REFSEL[2:0]
R/W
0
0
R/W
0
Bits 6:4 – ADC0REFSEL[2:0] ADC0 Reference Select
This bit field selects the reference voltage for the ADC0.
Value
Description
0x0
0.55V
0x1
1.1V
0x2
2.5V
0x3
4.3V
0x4
1.5V
other
Reserved
Bits 2:0 – DAC0REFSEL[2:0] DAC0 and AC0 Reference Select
This bit field selects the reference voltage for DAC0 and AC0.
Value
Description
0x0
0.55V
0x1
1.1V
0x2
2.5V
0x3
4.3V
0x4
1.5V
other
Reserved
© 2020 Microchip Technology Inc.
Complete Datasheet
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ATtiny212/214/412/414/416
VREF - Voltage Reference
18.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x01
0x00
-
6
5
4
3
Access
Reset
2
1
ADC0REFEN
R/W
0
0
DAC0REFEN
R/W
0
Bit 1 – ADC0REFEN ADC0 Reference Force Enable
Writing a '1' to this bit forces the voltage reference for the ADC0 to be running, even if it is not requested.
Writing a '0' to this bit allows automatic enable/disable of the reference source by the peripheral.
Bit 0 – DAC0REFEN DAC0 and AC0 Reference Force Enable
Writing a '1' to this bit forces the voltage reference for the DAC0 and AC0 to be running, even if it is not requested.
Writing a '0' to this bit allows automatic enable/disable of the reference source by the peripheral.
© 2020 Microchip Technology Inc.
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
19.
WDT - Watchdog Timer
19.1
Features
•
•
•
•
•
•
•
19.2
Issues a System Reset if the Watchdog Timer is not Cleared Before its Time-out Period
Operating Asynchronously from System Clock Using an Independent Oscillator
Using the 1.024 kHz Output of the 32.768 kHz Ultra Low-Power Oscillator (OSCULP32K)
11 Selectable Time-out Periods, from 8 ms to 8s
Two Operation Modes:
– Normal mode
– Window mode
Configuration Lock to Prevent Unwanted Changes
Closed Period Timer Activation After First WDT Instruction for Easy Setup
Overview
The Watchdog Timer (WDT) is a system function for monitoring correct program operation. It allows the system to
recover from situations such as runaway or deadlocked code by issuing a Reset. When enabled, the WDT is a
constantly running timer configured to a predefined time-out period. If the WDT is not reset within the time-out period,
it will issue a system Reset. The WDT is reset by executing the Watchdog Timer Reset (WDR) instruction from
software.
The WDT has two modes of operation: Normal mode and Window mode. The settings in the Control A (WDT.CTRLA)
register determine the mode of operation.
A Window mode defines a time slot or "window" inside the time-out period during which the WDT must be reset. If the
WDT is reset outside this window, either too early or too late, a system Reset will be issued. Compared to the Normal
mode, the Window mode can catch situations where a code error causes constant WDR execution.
When enabled, the WDT will run in Active mode and all sleep modes. It is asynchronous (i.e., running from a CPU
independent clock source). For this reason, it will continue to operate and be able to issue a system Reset even if the
main clock fails.
The CCP mechanism ensures that the WDT settings cannot be changed by accident. For increased safety, a
configuration for locking the WDT settings is available.
© 2020 Microchip Technology Inc.
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
19.2.1
Block Diagram
Figure 19-1. WDT Block Diagram
"Inside closed window"
CTRLA
WINDOW
CLK_WDT
=
"Enable
open window
and clear count"
COUNT
PERIOD
=
System
Reset
CTRLA
WDR
(instruction)
19.2.2
Signal Description
Not applicable.
19.3
Functional Description
19.3.1
Initialization
•
•
The WDT is enabled when a non-zero value is written to the Period (PERIOD) bits in the Control A
(WDT.CTRLA) register
Optional: Write a non-zero value to the Window (WINDOW) bits in WDT.CTRLA to enable the Window mode
operation.
All bits in the Control A register and the Lock (LOCK) bit in the STATUS (WDT.STATUS) register are write-protected
by the Configuration Change Protection mechanism.
The Reset value of WDT.CTRLA is defined by a fuse (FUSE.WDTCFG), so the WDT can be enabled at boot time. If
this is the case, the LOCK bit in WDT.STATUS is set at boot time.
19.3.2
Clocks
A 1.024 kHz Oscillator Clock (CLK_WDT_OSC) is sourced from the internal Ultra Low-Power Oscillator,
OSCULP32K. Due to the ultra low-power design, the oscillator is not very accurate, and so the exact time-out period
may vary from device to device. This variation must be kept in mind when designing software that uses the WDT to
ensure that the time-out periods used are valid for all devices.
The 1.024 kHz Oscillator Clock, CLK_WDT_OSC, is asynchronous to the system clock. Due to this asynchronicity,
writing to the WDT Control register will require synchronization between the clock domains.
19.3.3
Operation
19.3.3.1 Normal Mode
In Normal mode operation, a single time-out period is set for the WDT. If the WDT is not reset from software using the
WDR any time before the time-out occurs, the WDT will issue a system Reset.
A new WDT time-out period will be started each time the WDT is reset by WDR.
There are 11 possible WDT time-out periods (TOWDT), selectable from 8 ms to 8s by writing to the Period (PERIOD)
bit field in the Control A (WDT.CTRLA) register.
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
Figure 19-2. Normal Mode Operation
WDT Count
Timely WDT Reset (WDR)
WDT Timeout
System Reset
Here:
TO WDT = 16 ms
5
10
15
20
25
30
TOWDT
35
t [ms]
Normal mode is enabled as long as the WINDOW bit field in the Control A (WDT.CTRLA) register is 0x0.
19.3.3.2 Window Mode
In Window mode operation, the WDT uses two different time-out periods: A closed Window Time-out period
(TOWDTW) and the normal time-out period (TOWDT):
• The closed window time-out period defines a duration from 8 ms to 8s, where the WDT cannot be reset. If the
WDT is reset during this period, the WDT will issue a system Reset.
• The normal WDT time-out period, which is also 8 ms to 8s, defines the duration of the open period during which
the WDT can (and needs to) be reset. The open period will always follow the closed period, so the total duration
of the time-out period is the sum of the closed window and the open window time-out periods.
When enabling Window mode or when going out of Debug mode, the first closed period is activated after the first WDR
instruction.
If a second WDR is issued while a previous WDR is being synchronized, the second one will be ignored.
Figure 19-3. Window Mode Operation
WDT Count
Open
Timely WDT Reset (WDR)
Closed
WDR too early:
System Reset
Here:
TOWDTW =TOWDT = 8 ms
5
10
15
20
TOWDTW
25
30
TOWDT
35
t [ms]
The Window mode is enabled by writing a non-zero value to the WINDOW bit field in the Control A (WDT.CTRLA)
register, and disabled by writing it to 0x0.
19.3.3.3 Configuration Protection and Lock
The WDT provides two security mechanisms to avoid unintentional changes to the WDT settings.
The first mechanism is the Configuration Change Protection mechanism, employing a timed-write procedure for
changing the WDT control registers.
The second mechanism locks the configuration by writing a ‘1’ to the LOCK bit in the STATUS (WDT.STATUS)
register. When this bit is ‘1’, the Control A (WDT.CTRLA) register cannot be changed. Consequently, the WDT cannot
be disabled from the software.
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
LOCK in WDT.STATUS can only be written to ‘1’. It can only be cleared in Debug mode.
If the WDT configuration is loaded from fuses, LOCK is automatically set in WDT.STATUS.
19.3.4
Sleep Mode Operation
The WDT will continue to operate in any sleep mode where the source clock is Active.
19.3.5
Debug Operation
When run-time debugging, this peripheral will continue normal operation. Halting the CPU in Debugging mode will
halt the normal operation of the peripheral.
When halting the CPU in Debug mode, the WDT counter is reset.
When starting the CPU again and the WDT is operating in Window mode, the first closed window time-out period will
be disabled, and a Normal mode time-out period is executed.
19.3.6
Synchronization
Due to asynchronicity between the main clock domain and the peripheral clock domain, the Control A (WDT.CTRLA)
register is synchronized when written. The Synchronization Busy (SYNCBUSY) flag in the STATUS (WDT.STATUS)
register indicates if there is an ongoing synchronization.
Writing to WDT.CTRLA while SYNCBUSY=1 is not allowed.
The following registers are synchronized when written:
• PERIOD bits in Control A (WDT.CTRLA) register
• Window Period (WINDOW) bits in WDT.CTRLA
The WDR instruction will need two to three cycles of the WDT clock to be synchronized. Issuing a new WDR instruction
while a WDR instruction is being synchronized will be ignored.
19.3.7
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 19-1. WDT - Registers Under Configuration Change Protection
Register
Key
WDT.CTRLA
IOREG
LOCK bit in WDT.STATUS
IOREG
List of bits/registers protected by CCP:
•
•
•
Period bits in Control A (CTRLA.PERIOD) register
Window Period bits in Control A (CTRLA.WINDOW) register
LOCK bit in STATUS (STATUS.LOCK) register
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
19.4
Register Summary - WDT
Offset
Name
Bit Pos.
7
0x00
0x01
CTRLA
STATUS
7:0
7:0
LOCK
19.5
6
5
4
WINDOW[3:0]
3
2
1
0
PERIOD[3:0]
SYNCBUSY
Register Description
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ATtiny212/214/412/414/416
WDT - Watchdog Timer
19.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
Access
Reset
R/W
x
CTRLA
0x00
From FUSE.WDTCFG
Configuration Change Protection
6
5
WINDOW[3:0]
R/W
R/W
x
x
4
3
R/W
x
R/W
x
2
1
PERIOD[3:0]
R/W
R/W
x
x
0
R/W
x
Bits 7:4 – WINDOW[3:0] Window
Writing a non-zero value to these bits enables the Window mode, and selects the duration of the closed period
accordingly.
The bits are optionally lock-protected:
• If LOCK bit in WDT.STATUS is ‘1’, all bits are change-protected (Access = R)
•
If LOCK bit in WDT.STATUS is ‘0’, all bits can be changed (Access = R/W)
Value
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
other
Name
OFF
8CLK
16CLK
32CLK
64CLK
128CLK
256CLK
512CLK
1KCLK
2KCLK
4KCLK
8KCLK
-
Description
0.008s
0.016s
0.031s
0.063s
0.125s
0.25s
0.5s
1s
2s
4s
8s
Reserved
Bits 3:0 – PERIOD[3:0] Period
Writing a non-zero value to this bit enables the WDT, and selects the time-out period in Normal mode accordingly. In
Window mode, these bits select the duration of the open window.
The bits are optionally lock-protected:
• If LOCK in WDT.STATUS is ‘1’, all bits are change-protected (Access = R)
•
If LOCK in WDT.STATUS is ‘0’, all bits can be changed (Access = R/W)
Value
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
other
Name
OFF
8CLK
16CLK
32CLK
64CLK
128CLK
256CLK
512CLK
1KCLK
2KCLK
4KCLK
8KCLK
-
© 2020 Microchip Technology Inc.
Description
0.008s
0.016s
0.031s
0.063s
0.125s
0.25s
0.5s
1s
2s
4s
8s
Reserved
Complete Datasheet
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WDT - Watchdog Timer
19.5.2
Status
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
LOCK
R/W
0
STATUS
0x01
0x00
Configuration Change Protection
6
5
4
3
2
1
0
SYNCBUSY
R
0
Bit 7 – LOCK Lock
Writing this bit to ‘1’ write-protects the WDT.CTRLA register.
It is only possible to write this bit to ‘1’. This bit can be cleared in Debug mode only.
If the PERIOD bits in WDT.CTRLA are different from zero after boot code, the lock will be automatically set.
This bit is under CCP.
Bit 0 – SYNCBUSY Synchronization Busy
This bit is set after writing to the WDT.CTRLA register, while the data is being synchronized from the system clock
domain to the WDT clock domain.
This bit is cleared by the system after the synchronization is finished.
This bit is not under CCP.
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TCA - 16-bit Timer/Counter Type A
20.
TCA - 16-bit Timer/Counter Type A
20.1
Features
•
•
•
•
•
•
•
•
•
20.2
16-Bit Timer/Counter
Three Compare Channels
Double-Buffered Timer Period Setting
Double-Buffered Compare Channels
Waveform Generation:
– Frequency generation
– Single-slope PWM (Pulse-Width Modulation)
– Dual-slope PWM
Count on Event
Timer Overflow Interrupts/Events
One Compare Match per Compare Channel
Two 8-Bit Timer/Counters in Split Mode
Overview
The flexible 16-bit PWM Timer/Counter type A (TCA) provides accurate program execution timing, frequency and
waveform generation, and command execution.
A TCA consists of a base counter and a set of compare channels. The base counter can be used to count clock
cycles or events or let events control how it counts clock cycles. It has direction control and period setting that can be
used for timing. The compare channels can be used together with the base counter to perform a compare match
control, frequency generation, and pulse-width waveform modulation.
Depending on the mode of operation, the counter is cleared, reloaded, incremented, or decremented at each timer/
counter clock or event input.
A timer/counter can be clocked and timed from the peripheral clock, with optional prescaling, or from the Event
System. The Event System can also be used for direction control or to synchronize operations.
By default, the TCA is a 16-bit timer/counter. The timer/counter has a Split mode feature that splits it into two 8-bit
timer/counters with three compare channels each.
A block diagram of the 16-bit timer/counter with closely related peripheral modules (in grey) is shown in the figure
below.
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
Figure 20-1. 16-bit Timer/Counter and Closely Related Peripherals
Timer/Counter
Base Counter
Timer Period
Counter
Prescaler
Control Logic
Event
System
Waveform
Generation
Buffer
Block Diagram
The figure below shows a detailed block diagram of the timer/counter.
Figure 20-2. Timer/Counter Block Diagram
Base Counter
Clock Select
CTRL A
BV
PERBUF
Mode
CTRL B
PER
EVCTRL
Event
Action
‘‘count’’
‘‘clear’’
‘‘load’’
‘‘direction’’
Counter
CNT
=
=0
TOP
BOTTOM
OVF
(INT Req. and Event)
Control Logic
Event
UPDATE
20.2.1
PORTS
Compare Channel 0
Compare Channel 1
Compare Channel 2
Comparator
CLK_PER
Compare Unit n
BV
CMPnBUF
Control Logic
CMPn
=
© 2020 Microchip Technology Inc.
Waveform
Generation
‘‘match’’
Complete Datasheet
WOn Out
CMPn
(INT Req. and Event)
DS40002287A-page 179
ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
The Counter (TCAn.CNT) register, Period and Compare (TCAn.PER and TCAn.CMPn) registers, and their
corresponding buffer registers (TCAn.PERBUF and TCAn.CMPnBUF) are 16-bit registers. All buffer registers have a
Buffer Valid (BV) flag that indicates when the buffer contains a new value.
During normal operation, the counter value is continuously compared to zero and the period (PER) value to
determine whether the counter has reached TOP or BOTTOM. The counter value can also be compared to the
TCAn.CMPn registers.
The timer/counter can generate interrupt requests, events, or change the waveform output after being triggered by
the Counter (TCAn.CNT) register reaching TOP, BOTTOM, or CMPn. The interrupt requests, events, or waveform
output changes will occur on the next CLK_TCA cycle after the triggering.
CLK_TCA is either the prescaled peripheral clock or events from the Event System, as shown in the figure below.
Figure 20-3. Timer/Counter Clock Logic
CLK_PER
Prescaler
Event System
Event
CLKSEL
EVACT
(Encoding)
CLK_TCA
CNT
CNTxEI
20.2.2
Signal Description
Signal
Description
Type
WOn
Digital output
Waveform output
20.3
Functional Description
20.3.1
Definitions
The following definitions are used throughout the documentation:
Table 20-1. Timer/Counter Definitions
Name
Description
BOTTOM The counter reaches BOTTOM when it becomes 0x0000
MAX
The counter reaches MAXimum when it becomes all ones
TOP
The counter reaches TOP when it becomes equal to the highest value in the count sequence
The update condition is met when the timer/counter reaches BOTTOM or TOP, depending on the
UPDATE Waveform Generator mode. Buffered registers with valid buffer values will be updated unless the Lock
Update (LUPD) bit in the TCAn.CTRLE register has been set.
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TCA - 16-bit Timer/Counter Type A
...........continued
Name
Description
CNT
Counter register value
CMP
Compare register value
PER
Period register value
In general, the term timer is used when the timer/counter is counting periodic clock ticks. The term counter is used
when the input signal has sporadic or irregular ticks. The latter can be the case when counting events.
20.3.2
Initialization
To start using the timer/counter in basic mode, follow these steps:
1. Write a TOP value to the Period (TCAn.PER) register.
2. Enable the peripheral by writing a ‘1’ to the ENABLE bit in the Control A (TCAn.CTRLA) register.
The counter will start counting clock ticks according to the prescaler setting in the Clock Select (CLKSEL) bit
field in the TCAn.CTRLA register.
3. Optional: By writing a ‘1’ to the Enable Count on Event Input (CNTEI) bit in the Event Control (TCAn.EVCTRL)
register, events are counted instead of clock ticks.
4. The counter value can be read from the Counter (CNT) bit field in the Counter (TCAn.CNT) register.
20.3.3
Operation
20.3.3.1 Normal Operation
In normal operation the counter is counting clock ticks in the direction selected by the Direction (DIR) bit in the
Control E (TCAn.CTRLE) register until it reaches TOP or BOTTOM. The clock ticks are given by the peripheral clock
(CLK_PER), prescaled according to the Clock Select (CLKSEL) bit field in the Control A (TCAn.CTRLA) register.
When TOP is reached while the counter is counting up, the counter will wrap to ‘0’ at the next clock tick. When
counting down, the counter is reloaded with the Period (TCAn.PER) register value when the BOTTOM is reached.
Figure 20-4. Normal Operation
CNT written
MAX
‘‘update’’
CNT
TOP
BOTTOM
DIR
It is possible to change the counter value in the Counter (TCAn.CNT) register when the counter is running. The write
access to TCAn.CNT register has higher priority than count, clear or reload, and will be immediate. The direction of
the counter can also be changed during normal operation by writing to the Direction (DIR) bit in the Control E
(TCAn.CTRLE) register.
20.3.3.2 Double Buffering
The Period (TCAn.PER) register value and the Compare n (TCAn.CMPn) register values are all double-buffered
(TCAn.PERBUF and TCAn.CMPnBUF).
Each buffer register has a Buffer Valid (BV) flag (PERBV, CMPnBV) in the Control F (TCAn.CTRLF) register, which
indicates that the buffer register contains a valid (new) value that can be copied into the corresponding Period or
Compare register. When the Period register and Compare n registers are used for a compare operation, the BV flag
is set when data are written to the buffer register and cleared on an UPDATE condition. This is shown for a Compare
(CMPn) register in the figure below.
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TCA - 16-bit Timer/Counter Type A
Figure 20-5. Period and Compare Double Buffering
‘‘write enable’’
BV
EN
EN
UPDATE
‘‘data write’’
CMPnBUF
CMPn
CNT
=
‘‘match’’
Both the TCAn.CMPn and TCAn.CMPnBUF registers are available as I/O registers. This allows the initialization and
bypassing of the buffer register and the double-buffering function.
20.3.3.3 Changing the Period
The Counter period is changed by writing a new TOP value to the Period (TCAn.PER) register.
No Buffering: If double-buffering is not used, any period update is immediate.
Figure 20-6. Changing the Period Without Buffering
Counter wrap-around
MAX
‘‘update’’
‘‘write’’
CNT
BOTTOM
New TOP written to
New TOP written to
PER that is higher
PER that is lower
than current CNT.
than current CNT.
A counter wrap-around can occur in any mode of operation when counting up without buffering, as the TCAn.CNT
and TCAn.PER registers are continuously compared. If a new TOP value is written to TCAn.PER that is lower than
the current TCAn.CNT, the counter will wrap first, before a compare match occurs.
Figure 20-7. Unbuffered Dual-Slope Operation
Counter wrap-around
MAX
‘‘update’’
‘‘write’’
CNT
BOTTOM
New TOP written to
PER that is higher
than current CNT.
New TOP written to
PER that is lower
than current CNT.
With Buffering: When double-buffering is used, the buffer can be written at any time and still maintain the correct
operation. The TCAn.PER is always updated on the UPDATE condition, as shown for dual-slope operation in the
figure below. This prevents wrap-around and the generation of odd waveforms.
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Figure 20-8. Changing the Period Using Buffering
MAX
‘‘update’’
‘‘write’’
CNT
BOTTOM
New Period written to
PERB that is higher
than current CNT.
New Period written to
PERB that is lower
than current CNT.
New PER is updated
with PERB value.
Note: Buffering is used in figures illustrating TCA operation if not otherwise specified.
20.3.3.4 Compare Channel
Each Compare Channel n continuously compares the counter value (TCAn.CNT) with the Compare n (TCAn.CMPn)
register. If TCAn.CNT equals TCAn.CMPn the Comparator n signals a match. The match will set the Compare
Channel’s interrupt flag at the next timer clock cycle, and the optional interrupt is generated.
The Compare n Buffer (TCAn.CMPnBUF) register provides double-buffer capability equivalent to that for the period
buffer. The double-buffering synchronizes the update of the TCAn.CMPn register with the buffer value to either the
TOP or BOTTOM of the counting sequence, according to the UPDATE condition. The synchronization prevents the
occurrence of odd-length, non-symmetrical pulses for glitch-free output.
The value in CMPnBUF is moved to CMPn at the UPDATE condition and is compared to the counter value
(TCAn.CNT) from the next count.
20.3.3.4.1 Waveform Generation
The compare channels can be used for waveform generation on the corresponding port pins. The following
requirements must be met to make the waveform visible on the connected port pin:
1.
2.
3.
4.
A Waveform Generation mode must be selected by writing the Waveform Generation Mode (WGMODE) bit
field in the TCAn.CTRLB register.
The compare channels used must be enabled (CMPnEN = 1 in TCAn.CTRLB). This will override the output
value for the corresponding pin. An alternative pin can be selected by configuring the Port Multiplexer
(PORTMUX). Refer to the PORTMUX section for details.
The direction for the associated port pin n must be configured in the Port peripheral as an output.
Optional: Enable the inverted waveform output for the associated port pin n. Refer to the PORT section for
details.
20.3.3.4.2 Frequency (FRQ) Waveform Generation
For frequency generation, the period time (T) is controlled by the TCAn.CMP0 register instead of the Period
(TCAn.PER) register. The corresponding waveform generator output is toggled on each compare match between the
TCAn.CNT and TCAn.CMPn registers.
Figure 20-9. Frequency Waveform Generation
Period (T)
Direction change
CNT written
MAX
‘‘update’’
CNT
TOP
BOTTOM
WG Output
The following equation defines the waveform frequency (fFRQ):
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TCA - 16-bit Timer/Counter Type A
�FRQ =
f CLK_PER
2� CMPn+1
where N represents the prescaler divider used (see the CLKSEL bit field in the TCAn.CTRLA register), and fCLK_PER
is the peripheral clock frequency.
The maximum frequency of the waveform generated is half of the peripheral clock frequency (fCLK_PER/2) when
TCAn.CMP0 is written to 0x0000 and no prescaling is used (N = 1, CLKSEL = 0x0 in TCAn.CTRLA).
20.3.3.4.3 Single-Slope PWM Generation
For single-slope Pulse-Width Modulation (PWM) generation, the period (T) is controlled by the TCAn.PER register,
while the values of the TCAn.CMPn registers control the duty cycles of the generated waveforms. The figure below
shows how the counter counts from BOTTOM to TOP and then restarts from BOTTOM. The waveform generator
output is set at BOTTOM and cleared on the compare match between the TCAn.CNT and TCAn.CMPn registers.
CMPn = BOTTOM will produce a static low signal on WOn while CMPn > TOP will produce a static high signal on
WOn.
Figure 20-10. Single-Slope Pulse-Width Modulation
Period (T)
CMPn=BOTTOM
CMPn>TOP
MAX
TOP
‘‘update’’
‘‘match’’
CNT
CMPn
BOTTOM
Output WOn
Notes:
1. The representation in the figure above is valid when CMPn is updated using CMPnBUF.
2. For single-slope Pulse-Width Modulation (PWM) generation, the counter counting from TOP to BOTTOM is not
supported.
The TCAn.PER register defines the PWM resolution. The minimum resolution is 2 bits (TCAn.PER = 0x0002), and
the maximum resolution is 16 bits (TCAn.PER = MAX-1).
The following equation calculates the exact resolution in bits for single-slope PWM (RPWM_SS):
�PWM_SS =
log PER+2
log 2
�PWM_SS =
�CLK_PER
� PER+1
The single-slope PWM frequency (fPWM_SS) depends on the period setting (TCAn.PER), the peripheral clock
frequency fCLK_PER and the TCA prescaler (the CLKSEL bit field in the TCAn.CTRLA register). It is calculated by the
following equation where N represents the prescaler divider used:
20.3.3.4.4 Dual-Slope PWM
For the dual-slope PWM generation, the period (T) is controlled by TCAn.PER, while the values of TCAn.CMPn
control the duty cycle of the WG output.
The figure below shows how, for dual-slope PWM, the counter repeatedly counts from BOTTOM to TOP and then
from TOP to BOTTOM. The waveform generator output is set at BOTTOM, cleared on compare match when upcounting, and set on compare match when down-counting.
CMPn = BOTTOM produces a static low signal on WOn, while CMPn = TOP produces a static high signal on WOn.
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Figure 20-11. Dual-Slope Pulse-Width Modulation
Period (T)
CMPn=BOTTOM
CMPn=TOP
‘‘update’’
‘‘match’’
MAX
CMPn
TOP
CNT
BOTTOM
Waveform Output WOn
Note: The representation in the figure above is valid when CMPn is updated using CMPnBUF.
The Period (TCAn.PER) register defines the PWM resolution. The minimum resolution is 2 bits (TCAn.PER =
0x0003), and the maximum resolution is 16 bits (TCAn.PER = MAX).
The following equation calculates the exact resolution in bits for dual-slope PWM (RPWM_DS):
�PWM_DS =
log PER+1
log 2
�PWM_DS =
�CLK_PER
2� ⋅ PER
The PWM frequency depends on the period setting in the TCAn.PER register, the peripheral clock frequency
(fCLK_PER), and the prescaler divider selected in the CLKSEL bit field in the TCAn.CTRLA register. It is calculated by
the following equation:
N represents the prescaler divider used.
Using dual-slope PWM results in approximately half the maximum operation frequency compared to single-slope
PWM operation, due to twice the number of timer increments per period.
20.3.3.4.5 Port Override for Waveform Generation
To make the waveform generation available on the port pins, the corresponding port pin direction must be set as
output (PORTx.DIR[n] = 1). The TCA will override the port pin values when the compare channel is enabled
(CMPnEN = 1 in the TCAn.CTRLB register), and a Waveform Generation mode is selected.
The figure below shows the port override for TCA. The timer/counter compare channel will override the port pin
output value (PORTx.OUT) on the corresponding port pin. Enabling inverted I/O on the port pin (INVEN = 1 in the
PORTx.PINnCTRL register) inverts the corresponding WG output.
Figure 20-12. Port Override for Timer/Counter Type A
OUT
WOn
Waveform
CMPnEN
INVEN
20.3.3.5 Timer/Counter Commands
A set of commands can be issued by software to immediately change the state of the peripheral. These commands
give direct control of the UPDATE, RESTART and RESET signals. A command is issued by writing the respective
value to the Command (CMD) bit field in the Control E (TCAn.CTRLESET) register.
An UPDATE command has the same effect as when an UPDATE condition occurs, except that the UPDATE
command is not affected by the state of the Lock Update (LUPD) bit in the Control E (TCAn.CTRLE) register.
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TCA - 16-bit Timer/Counter Type A
The software can force a restart of the current waveform period by issuing a RESTART command. In this case, the
counter, direction, and all compare outputs are set to ‘0’.
A RESET command will set all timer/counter registers to their initial values. A RESET command can be issued only
when the timer/counter is not running (ENABLE = 0 in the TCAn.CTRLA register).
20.3.3.6 Split Mode - Two 8-Bit Timer/Counters
Split Mode Overview
To double the number of timers and PWM channels in the TCA, a Split mode is provided. In this Split mode, the 16-bit
timer/counter acts as two separate 8-bit timers, which each have three compare channels for PWM generation. The
Split mode will only work with single-slope down-count. Event controlled operation is not supported in Split mode.
Activating Split mode results in changes to the functionality of some registers and register bits. The modifications are
described in a separate register map (see 20.6 Register Summary - Split Mode).
Split Mode Differences Compared to Normal Mode
• Count:
– Down-count only
– Low Byte Timer Counter (TCAn.LCNT) register and High Byte Timer Counter (TCAn.HCNT) register are
independent
• Waveform generation:
– Single-slope PWM only (WGMODE = SINGLESLOPE in the TCAn.CTRLB register)
• Interrupt:
– No change for Low Byte Timer Counter (TCAn.LCNT) register
– Underflow interrupt for High Byte Timer Counter (TCAn.HCNT) register
– No compare interrupt or flag for High Byte Compare n (TCAn.HCMPn) register
• Event Actions: Not compatible
• Buffer registers and buffer valid flags: Unused
• Register Access: Byte access to all registers
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Block Diagram
Figure 20-13. Timer/Counter Block Diagram Split Mode
‘‘
‘‘
‘‘
‘‘
Control Logic
‘‘
‘‘
Split Mode Initialization
When shifting between Normal mode and Split mode, the functionality of some registers and bits changes, but their
values do not. For this reason, disabling the peripheral (ENABLE = 0 in the TCAn.CTRLA register) and doing a hard
Reset (CMD = RESET in the TCAn.CTRLESET register) is recommended when changing the mode to avoid
unexpected behavior.
To start using the timer/counter in basic Split mode after a hard Reset, follow these steps:
1. Enable Split mode by writing a ‘1’ to the Split mode enable (SPLITM) bit in the Control D (TCAn.CTRLD)
register.
2. Write a TOP value to the Period (TCAn.PER) registers.
3. Enable the peripheral by writing a ‘1’ to the Enable (ENABLE) bit in the Control A (TCAn.CTRLA) register.
The counter will start counting clock ticks according to the prescaler setting in the Clock Select (CLKSEL) bit
field in the TCAn.CTRLA register.
4. The counter values can be read from the Counter bit field in the Counter (TCAn.CNT) registers.
20.3.4
Events
The TCA can generate the events described in the table below. All event generators except TCAn_HUNF are shared
between Normal mode and Split mode operation.
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Table 20-2. Event Generators in TCA
Generator Name
Peripheral
Description
Event
OVF_LUNF
HUNF
CMP0
TCAn
CMP1
CMP2
Normal mode: Overflow
Split mode: Low byte timer underflow
Normal mode: Not available
Split mode: High byte timer underflow
Normal mode: Compare Channel 0
match
Split mode: Low byte timer Compare
Channel 0 match
Normal mode: Compare Channel 1
match
Split mode: Low byte timer Compare
Channel 1 match
Normal mode: Compare Channel 2
match
Split mode: Low byte timer Compare
Channel 2 match
Event
Type
Generating
Clock Domain
Pulse
CLK_PER
One CLK_PER
period
Pulse
CLK_PER
One CLK_PER
period
Pulse
CLK_PER
One CLK_PER
period
Pulse
CLK_PER
One CLK_PER
period
Pulse
CLK_PER
One CLK_PER
period
Length of Event
Note: The conditions for generating an event are identical to those that will raise the corresponding interrupt flag in
the TCAn.INTFLAGS register for both Normal mode and Split mode.
The TCA has one event user for detecting and acting upon input events. The table below describes the event user
and the associated functionality.
Table 20-3. Event User in TCA
User Name
Description
Peripheral Input
TCAn
Input Detection Async/Sync
Count on a positive event edge
Edge
Sync
Count on any event edge
Edge
Sync
Level
Sync
Level
Sync
CNT Count while the event signal is high
The event level controls the count direction, up when low and
down when high
Notes:
1. Event inputs are not used in Split mode.
2. Event actions with level input detection only work reliably if the event frequency is less than the timer’s
frequency.
The specific actions described in the table above are selected by writing to the Event Action (EVACT) bit field in the
Event Control (TCAn.EVCTRL) register. Input events are enabled by writing a ‘1’ to the Enable Count on Event Input
(CNTEI) bit in the Event Control (TCAn.EVCTRL) register.
Refer to the Event System (EVSYS) chapter for more details regarding event types and Event System configuration.
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20.3.5
Interrupts
Table 20-4. Available Interrupt Vectors and Sources in Normal Mode
Name
OVF
Vector Description
Overflow or underflow interrupt
Conditions
The counter has reached TOP or BOTTOM
CMP0 Compare Channel 0 interrupt
Match between the counter value and the Compare 0 register
CMP1 Compare Channel 1 interrupt
Match between the counter value and the Compare 1 register
CMP2 Compare Channel 2 interrupt
Match between the counter value and the Compare 2 register
Table 20-5. Available Interrupt Vectors and Sources in Split Mode
Name
Vector Description
Conditions
LUNF
Low-byte Underflow interrupt Low byte timer reaches BOTTOM
HUNF
High-byte Underflow interrupt High byte timer reaches BOTTOM
LCMP0 Compare Channel 0 interrupt
Match between the counter value and the low byte of the Compare 0
register
LCMP1 Compare Channel 1 interrupt
Match between the counter value and the low byte of the Compare 1
register
LCMP2 Compare Channel 2 interrupt
Match between the counter value and the low byte of the Compare 2
register
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
20.3.6
Sleep Mode Operation
The timer/counter will continue operation in Idle sleep mode.
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20.4
Register Summary - Normal Mode
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
...
0x0D
0x0E
0x0F
0x10
...
0x1F
CTRLA
CTRLB
CTRLC
CTRLD
CTRLECLR
CTRLESET
CTRLFCLR
CTRLFSET
Reserved
EVCTRL
INTCTRL
INTFLAGS
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
0x20
CNT
0x22
...
0x25
Reserved
0x26
PER
0x28
CMP0
0x2A
CMP1
0x2C
CMP2
0x2E
...
0x35
Reserved
0x36
PERBUF
0x38
CMP0BUF
0x3A
CMP1BUF
0x3C
CMP2BUF
20.5
7
7:0
7:0
7:0
6
5
4
3
CMP2EN
CMP1EN
CMP0EN
ALUPD
2
1
CLKSEL[2:0]
CMP2OV
CMD[1:0]
CMD[1:0]
CMP2BV
CMP1BV
CMP2BV
CMP1BV
EVACT[2:0]
CMP2
CMP2
CMP1
CMP1
CMP0
CMP0
0
ENABLE
WGMODE[2:0]
CMP1OV
LUPD
LUPD
CMP0BV
CMP0BV
CMP0OV
SPLITM
DIR
DIR
PERBV
PERBV
CNTEI
OVF
OVF
Reserved
DBGCTRL
TEMP
7:0
7:0
TEMP[7:0]
DBGRUN
7:0
15:8
CNT[7:0]
CNT[15:8]
7:0
15:8
7:0
15:8
7:0
15:8
7:0
15:8
PER[7:0]
PER[15:8]
CMP[7:0]
CMP[15:8]
CMP[7:0]
CMP[15:8]
CMP[7:0]
CMP[15:8]
Reserved
7:0
PERBUF[7:0]
15:8
7:0
15:8
7:0
15:8
7:0
15:8
PERBUF[15:8]
CMPBUF[7:0]
CMPBUF[15:8]
CMPBUF[7:0]
CMPBUF[15:8]
CMPBUF[7:0]
CMPBUF[15:8]
Register Description - Normal Mode
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20.5.1
Control A - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
0x00
-
6
5
Access
Reset
4
3
R/W
0
2
CLKSEL[2:0]
R/W
0
1
R/W
0
0
ENABLE
R/W
0
Bits 3:1 – CLKSEL[2:0] Clock Select
This bit field selects the clock frequency for the timer/counter.
Value
Name
Description
0x0
DIV1
fTCA = fCLK_PER
0x1
DIV2
fTCA = fCLK_PER/2
0x2
DIV4
fTCA = fCLK_PER/4
0x3
DIV8
fTCA = fCLK_PER/8
0x4
DIV16
fTCA = fCLK_PER/16
0x5
DIV64
fTCA = fCLK_PER/64
0x6
DIV256
fTCA = fCLK_PER/256
0x7
DIV1024
fTCA = fCLK_PER/1024
Bit 0 – ENABLE Enable
Value
Description
0
The peripheral is disabled
1
The peripheral is enabled
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20.5.2
Control B - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
7
Access
Reset
CTRLB
0x01
0x00
-
6
CMP2EN
R/W
0
5
CMP1EN
R/W
0
4
CMP0EN
R/W
0
3
ALUPD
R/W
0
2
R/W
0
1
WGMODE[2:0]
R/W
0
0
R/W
0
Bits 4, 5, 6 – CMPEN Compare n Enable
In the FRQ and PWM Waveform Generation modes, the Compare n Enable (CMPnEN) bits will make the waveform
output available on the pin corresponding to WOn, overriding the value in the corresponding PORT output register.
The corresponding pin direction must be configured as an output in the PORT peripheral.
Value
Description
0
Waveform output WOn will not be available on the corresponding pin
1
Waveform output WOn will override the output value of the corresponding pin
Bit 3 – ALUPD Auto-Lock Update
The Auto-Lock Update bit controls the Lock Update (LUPD) bit in the TCAn.CTRLE register. When ALUPD is written
to ‘1’, the LUPD bit will be set to ‘1’ until the Buffer Valid (CMPnBV) bits of all enabled compare channels are ‘1’. This
condition will clear the LUPD bit.
It will remain cleared until the next UPDATE condition, where the buffer values will be transferred to the CMPn
registers, and the LUPD bit will be set to ‘1’ again. This makes sure that the CMPnBUF register values are not
transferred to the CMPn registers until all enabled compare buffers are written.
Value
Description
0
LUPD bit in the TCAn.CTRLE register is not altered by the system
1
LUPD bit in the TCAn.CTRLE register is set and cleared automatically
Bits 2:0 – WGMODE[2:0] Waveform Generation Mode
This bit field selects the Waveform Generation mode and controls the counting sequence of the counter, TOP value,
UPDATE condition, Interrupt condition, and the type of waveform generated.
No waveform generation is performed in the Normal mode of operation. For all other modes, the waveform generator
output will only be directed to the port pins if the corresponding CMPnEN bit has been set. The port pin direction must
be set as output.
Table 20-6. Timer Waveform Generation Mode
Value
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Group Configuration
NORMAL
FRQ
SINGLESLOPE
DSTOP
DSBOTH
DSBOTTOM
Mode of Operation
Normal
Frequency
Reserved
Single-slope PWM
Reserved
Dual-slope PWM
Dual-slope PWM
Dual-slope PWM
TOP
UPDATE
OVF
PER
CMP0
PER
PER
PER
PER
TOP(1)
TOP(1)
TOP(1)
BOTTOM
TOP
TOP and BOTTOM
BOTTOM
TOP(1)
BOTTOM
BOTTOM
BOTTOM
BOTTOM
Note:
1. When counting up.
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.5.3
Control C - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
7
CTRLC
0x02
0x00
-
6
5
4
3
Access
Reset
2
CMP2OV
R/W
0
1
CMP1OV
R/W
0
0
CMP0OV
R/W
0
Bit 2 – CMP2OV Compare Output Value 2
See CMP0OV.
Bit 1 – CMP1OV Compare Output Value 1
See CMP0OV.
Bit 0 – CMP0OV Compare Output Value 0
The CMPnOV bits allow direct access to the waveform generator’s output compare value when the timer/counter is
not enabled. This is used to set or clear the WG output value when the timer/counter is not running.
Note:
1. When the output is connected to the pad, overriding these bits will not work unless the CMPnEN bits in the
TCAn.CTRLB register have been set. If the output is connected to CCL, the CMPnEN bits in the TCAn.CTRLB
register are bypassed.
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TCA - 16-bit Timer/Counter Type A
20.5.4
Control D - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
7
CTRLD
0x03
0x00
-
6
5
4
3
Access
Reset
2
1
0
SPLITM
R/W
0
Bit 0 – SPLITM Enable Split Mode
This bit sets the timer/counter in Split mode operation and will work as two 8-bit timer/counters. The register map will
change compared to the normal 16-bit mode.
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.5.5
Control Register E Clear - Normal Mode
Name:
Offset:
Reset:
Property:
CTRLECLR
0x04
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to clear individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
4
3
2
CMD[1:0]
Access
Reset
R/W
0
R/W
0
1
LUPD
R/W
0
0
DIR
R/W
0
Bits 3:2 – CMD[1:0] Command
This bit field is used for software control of update, restart, and Reset of the timer/counter. The command bit field is
always read as ‘0’.
Value
Name
Description
0x0
NONE
No command
0x1
UPDATE
Force update
0x2
RESTART
Force restart
0x3
RESET
Force hard Reset (ignored if the timer/counter is enabled)
Bit 1 – LUPD Lock Update
Lock update can be used to ensure that all buffers are valid before an update is performed. This setting will not
prevent an update issued by the Command bit field.
Value
Description
0
The buffered registers are updated as soon as an UPDATE condition has occurred
1
No update of the buffered registers is performed, even though an UPDATE condition has occurred
Bit 0 – DIR Counter Direction
Normally this bit is controlled in hardware by the Waveform Generation mode or by event actions, but can also be
changed from the software.
Value
Description
0
The counter is counting up (incrementing)
1
The counter is counting down (decrementing)
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TCA - 16-bit Timer/Counter Type A
20.5.6
Control Register E Set - Normal Mode
Name:
Offset:
Reset:
Property:
CTRLESET
0x05
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to set individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
4
3
2
CMD[1:0]
Access
Reset
R/W
0
R/W
0
1
LUPD
R/W
0
0
DIR
R/W
0
Bits 3:2 – CMD[1:0] Command
This bit field is used for software control of update, restart, and Reset of the timer/counter. The command bit field is
always read as ‘0’.
Value
Name
Description
0x0
NONE
No command
0x1
UPDATE
Force update
0x2
RESTART
Force restart
0x3
RESET
Force hard Reset (ignored if the timer/counter is enabled)
Bit 1 – LUPD Lock Update
Locking the update ensures that all buffers are valid before an update is performed. This setting will not prevent an
update issued by the Command bit field.
Value
Description
0
The buffered registers are updated as soon as an UPDATE condition has occurred
1
No update of the buffered registers is performed, even though an UPDATE condition has occurred
Bit 0 – DIR Counter Direction
Normally this bit is controlled in hardware by the Waveform Generation mode or by event actions, but can also be
changed from the software.
Value
Description
0
The counter is counting up (incrementing)
1
The counter is counting down (decrementing)
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TCA - 16-bit Timer/Counter Type A
20.5.7
Control Register F Clear
Name:
Offset:
Reset:
Property:
CTRLFCLR
0x06
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to clear individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
Access
Reset
4
3
CMP2BV
R/W
0
2
CMP1BV
R/W
0
1
CMP0BV
R/W
0
0
PERBV
R/W
0
Bit 3 – CMP2BV Compare 2 Buffer Valid
See CMP0BV.
Bit 2 – CMP1BV Compare 1 Buffer Valid
See CMP0BV.
Bit 1 – CMP0BV Compare 0 Buffer Valid
The CMPnBV bits are set when a new value is written to the corresponding TCAn.CMPnBUF register. These bits are
automatically cleared on an UPDATE condition.
Bit 0 – PERBV Period Buffer Valid
This bit is set when a new value is written to the TCAn.PERBUF register. This bit is automatically cleared on an
UPDATE condition.
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TCA - 16-bit Timer/Counter Type A
20.5.8
Control Register F Set
Name:
Offset:
Reset:
Property:
CTRLFSET
0x07
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to set individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
Access
Reset
4
3
CMP2BV
R/W
0
2
CMP1BV
R/W
0
1
CMP0BV
R/W
0
0
PERBV
R/W
0
Bit 3 – CMP2BV Compare 2 Buffer Valid
See CMP0BV.
Bit 2 – CMP1BV Compare 1 Buffer Valid
See CMP0BV.
Bit 1 – CMP0BV Compare 0 Buffer Valid
The CMPnBV bits are set when a new value is written to the corresponding TCAn.CMPnBUF register. These bits are
automatically cleared on an UPDATE condition.
Bit 0 – PERBV Period Buffer Valid
This bit is set when a new value is written to the TCAn.PERBUF register. This bit is automatically cleared on an
UPDATE condition.
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TCA - 16-bit Timer/Counter Type A
20.5.9
Event Control
Name:
Offset:
Reset:
Property:
Bit
7
EVCTRL
0x09
0x00
-
6
Access
Reset
5
4
3
R/W
0
2
EVACT[2:0]
R/W
0
1
R/W
0
0
CNTEI
R/W
0
Bits 3:1 – EVACT[2:0] Event Action
This bit field defines what action the counter will take upon certain event conditions.
Value
Name
Description
0x0
EVACT_POSEDGE Count on positive event edge
0x1
EVACT_ANYEDGE Count on any event edge
0x2
EVACT_HIGHLVL Count prescaled clock cycles while the event signal is high
0x3
EVACT_UPDOWN Count prescaled clock cycles. The event signal controls the count direction, up
when low and down when high.
Other
Reserved
Bit 0 – CNTEI Enable Count on Event Input
Value
Description
0
Count on Event input is disabled
1
Count on Event input is enabled according to EVACT bit field
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TCA - 16-bit Timer/Counter Type A
20.5.10 Interrupt Control Register - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
INTCTRL
0x0A
0x00
-
6
CMP2
R/W
0
5
CMP1
R/W
0
4
CMP0
R/W
0
3
2
1
0
OVF
R/W
0
Bit 6 – CMP2 Compare Channel 2 Interrupt Enable
See CMP0.
Bit 5 – CMP1 Compare Channel 1 Interrupt Enable
See CMP0.
Bit 4 – CMP0 Compare Channel 0 Interrupt Enable
Writing the CMPn bit to ‘1’ enables the interrupt from Compare Channel n.
Bit 0 – OVF Timer Overflow/Underflow Interrupt Enable
Writing the OVF bit to ‘1’ enables the overflow/underflow interrupt.
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TCA - 16-bit Timer/Counter Type A
20.5.11 Interrupt Flag Register - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
INTFLAGS
0x0B
0x00
-
6
CMP2
R/W
0
5
CMP1
R/W
0
4
CMP0
R/W
0
3
2
1
0
OVF
R/W
0
Bit 6 – CMP2 Compare Channel 2 Interrupt Flag
See the CMP0 flag description.
Bit 5 – CMP1 Compare Channel 1 Interrupt Flag
See the CMP0 flag description.
Bit 4 – CMP0 Compare Channel 0 Interrupt Flag
The Compare Interrupt (CMPn) flag is set on a compare match on the corresponding compare channel.
For all modes of operation, the CMPn flag will be set when a compare match occurs between the Count (TCAn.CNT)
register and the corresponding Compare n (TCAn.CMPn) register. The CMPn flag is not cleared automatically. It will
be cleared only by writing a ‘1’ to its bit location.
Bit 0 – OVF Overflow/Underflow Interrupt Flag
This flag is set either on a TOP (overflow) or BOTTOM (underflow) condition, depending on the WGMODE setting.
The OVF flag is not cleared automatically. It will be cleared only by writing a ‘1’ to its bit location.
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TCA - 16-bit Timer/Counter Type A
20.5.12 Debug Control Register - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x0E
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Run in Debug
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.5.13 Temporary Bits for 16-Bit Access
Name:
Offset:
Reset:
Property:
TEMP
0x0F
0x00
-
The Temporary register is used by the CPU for 16-bit single-cycle access to the 16-bit registers of this peripheral. The
register is common for all the 16-bit registers of this peripheral and can be read and written by software. For more
details on reading and writing 16-bit registers, refer to Accessing 16-Bit Registers in the AVR CPU section.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
TEMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TEMP[7:0] Temporary Bits for 16-bit Access
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TCA - 16-bit Timer/Counter Type A
20.5.14 Counter Register - Normal Mode
Name:
Offset:
Reset:
Property:
CNT
0x20
0x00
-
The TCAn.CNTL and TCAn.CNTH register pair represents the 16-bit value, TCAn.CNT. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CNT[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
CNT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CNT[15:8] Counter High Byte
This bit field holds the MSB of the 16-bit Counter register.
Bits 7:0 – CNT[7:0] Counter Low Byte
This bit field holds the LSB of the 16-bit Counter register.
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TCA - 16-bit Timer/Counter Type A
20.5.15 Period Register - Normal Mode
Name:
Offset:
Reset:
Property:
PER
0x26
0xFFFF
-
The TCAn.PER register contains the 16-bit TOP value in the timer/counter in all modes of operation, except
Frequency Waveform Generation (FRQ).
The TCAn.PERL and TCAn.PERH register pair represents the 16-bit value, TCAn.PER. The low byte [7:0] (suffix L)
is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
PER[15:8]
Access
Reset
Bit
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
PER[7:0]
Access
Reset
R/W
1
R/W
1
R/W
1
R/W
1
Bits 15:8 – PER[15:8] Periodic High Byte
This bit field holds the MSB of the 16-bit Period register.
Bits 7:0 – PER[7:0] Periodic Low Byte
This bit field holds the LSB of the 16-bit Period register.
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.5.16 Compare n Register - Normal Mode
Name:
Offset:
Reset:
Property:
CMPn
0x28 + n*0x02 [n=0..2]
0x00
-
This register is continuously compared to the counter value. Normally, the outputs from the comparators are used to
generate waveforms.
The TCAn.CMPn registers are updated with the buffer value from their corresponding TCAn.CMPnBUF register when
an UPDATE condition occurs.
The TCAn.CMPnL and TCAn.CMPnH register pair represents the 16-bit value, TCAn.CMPn. The low byte [7:0]
(suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CMP[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
CMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CMP[15:8] Compare High Byte
This bit field holds the MSB of the 16-bit Compare register.
Bits 7:0 – CMP[7:0] Compare Low Byte
This bit filed holds the LSB of the 16-bit Compare register.
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TCA - 16-bit Timer/Counter Type A
20.5.17 Period Buffer Register
Name:
Offset:
Reset:
Property:
PERBUF
0x36
0xFFFF
-
This register serves as the buffer for the Period (TCAn.PER) register. Writing to this register from the CPU or UPDI
will set the Period Buffer Valid (PERBV) bit in the TCAn.CTRLF register.
The TCAn.PERBUFL and TCAn.PERBUFH register pair represents the 16-bit value, TCAn.PERBUF. The low byte
[7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
Access
Reset
Bit
Access
Reset
15
14
13
R/W
1
R/W
1
R/W
1
7
6
5
R/W
1
R/W
1
R/W
1
12
11
PERBUF[15:8]
R/W
R/W
1
1
4
3
PERBUF[7:0]
R/W
R/W
1
1
10
9
8
R/W
1
R/W
1
R/W
1
2
1
0
R/W
1
R/W
1
R/W
1
Bits 15:8 – PERBUF[15:8] Period Buffer High Byte
This bit field holds the MSB of the 16-bit Period Buffer register.
Bits 7:0 – PERBUF[7:0] Period Buffer Low Byte
This bit field holds the LSB of the 16-bit Period Buffer register.
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TCA - 16-bit Timer/Counter Type A
20.5.18 Compare n Buffer Register
Name:
Offset:
Reset:
Property:
CMPnBUF
0x38 + n*0x02 [n=0..2]
0x00
-
This register serves as the buffer for the associated Compare n (TCAn.CMPn) register. Writing to this register from
the CPU or UPDI will set the Compare Buffer valid (CMPnBV) bit in the TCAn.CTRLF register.
The TCAn.CMPnBUFL and TCAn.CMPnBUFH register pair represents the 16-bit value, TCAn.CMPnBUF. The low
byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset
+ 0x01.
Bit
Access
Reset
Bit
Access
Reset
15
14
13
R/W
0
R/W
0
R/W
0
7
6
5
R/W
0
R/W
0
R/W
0
12
11
CMPBUF[15:8]
R/W
R/W
0
0
4
3
CMPBUF[7:0]
R/W
R/W
0
0
10
9
8
R/W
0
R/W
0
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CMPBUF[15:8] Compare High Byte
This bit field holds the MSB of the 16-bit Compare Buffer register.
Bits 7:0 – CMPBUF[7:0] Compare Low Byte
This bit field holds the LSB of the 16-bit Compare Buffer register.
© 2020 Microchip Technology Inc.
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.6
Register Summary - Split Mode
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
...
0x09
0x0A
0x0B
0x0C
...
0x0D
0x0E
0x0F
...
0x1F
0x20
0x21
0x22
...
0x25
0x26
0x27
0x28
0x29
0x2A
0x2B
0x2C
0x2D
CTRLA
CTRLB
CTRLC
CTRLD
CTRLECLR
CTRLESET
7:0
7:0
7:0
7:0
7:0
7:0
20.7
7
6
5
4
3
HCMP2EN
HCMP2OV
HCMP1EN
HCMP1OV
HCMP0EN
HCMP0OV
2
1
CLKSEL[2:0]
LCMP2EN
LCMP2OV
LCMP1EN
LCMP1OV
CMD[1:0]
CMD[1:0]
0
ENABLE
LCMP0EN
LCMP0OV
SPLITM
CMDEN[1:0]
CMDEN[1:0]
Reserved
INTCTRL
INTFLAGS
7:0
7:0
LCMP2
LCMP2
LCMP1
LCMP1
LCMP0
LCMP0
HUNF
HUNF
LUNF
LUNF
Reserved
DBGCTRL
7:0
DBGRUN
Reserved
LCNT
HCNT
7:0
7:0
LCNT[7:0]
HCNT[7:0]
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
LPER[7:0]
HPER[7:0]
LCMP[7:0]
HCMP[7:0]
LCMP[7:0]
HCMP[7:0]
LCMP[7:0]
HCMP[7:0]
Reserved
LPER
HPER
LCMP0
HCMP0
LCMP1
HCMP1
LCMP2
HCMP2
Register Description - Split Mode
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ATtiny212/214/412/414/416
TCA - 16-bit Timer/Counter Type A
20.7.1
Control A - Split Mode
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
0x00
-
6
5
Access
Reset
4
3
R/W
0
2
CLKSEL[2:0]
R/W
0
1
R/W
0
0
ENABLE
R/W
0
Bits 3:1 – CLKSEL[2:0] Clock Select
This bit field selects the clock frequency for the timer/counter.
Value
Name
Description
0x0
DIV1
fTCA = fCLK_PER
0x1
DIV2
fTCA = fCLK_PER/2
0x2
DIV4
fTCA = fCLK_PER/4
0x3
DIV8
fTCA = fCLK_PER/8
0x4
DIV16
fTCA = fCLK_PER/16
0x5
DIV64
fTCA = fCLK_PER/64
0x6
DIV256
fTCA = fCLK_PER/256
0x7
DIV1024
fTCA = fCLK_PER/1024
Bit 0 – ENABLE Enable
Value
Description
0
The peripheral is disabled
1
The peripheral is enabled
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TCA - 16-bit Timer/Counter Type A
20.7.2
Control B - Split Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLB
0x01
0x00
-
6
HCMP2EN
R/W
0
5
HCMP1EN
R/W
0
4
HCMP0EN
R/W
0
3
2
LCMP2EN
R/W
0
1
LCMP1EN
R/W
0
0
LCMP0EN
R/W
0
Bit 6 – HCMP2EN High byte Compare 2 Enable
See HCMP0EN.
Bit 5 – HCMP1EN High byte Compare 1 Enable
See HCMP0EN.
Bit 4 – HCMP0EN High byte Compare 0 Enable
Setting the HCMPnEN bit in the FRQ or PWM Waveform Generation mode of operation will override the port output
register for the corresponding WO[n+3] pin.
Bit 2 – LCMP2EN Low byte Compare 2 Enable
See LCMP0EN.
Bit 1 – LCMP1EN Low byte Compare 1 Enable
See LCMP0EN.
Bit 0 – LCMP0EN Low byte Compare 0 Enable
Setting the LCMPnEN bit in the FRQ or PWM Waveform Generation mode of operation will override the port output
register for the corresponding WOn pin.
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TCA - 16-bit Timer/Counter Type A
20.7.3
Control C - Split Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLC
0x02
0x00
-
6
HCMP2OV
R/W
0
5
HCMP1OV
R/W
0
4
HCMP0OV
R/W
0
3
2
LCMP2OV
R/W
0
1
LCMP1OV
R/W
0
0
LCMP0OV
R/W
0
Bit 6 – HCMP2OV High byte Compare 2 Output Value
See HCMP0OV.
Bit 5 – HCMP1OV High byte Compare 1 Output Value
See HCMP0OV.
Bit 4 – HCMP0OV High byte Compare 0 Output Value
The HCMPnOV bit allows direct access to the output compare value of the waveform generator when the timer/
counter is not enabled. This is used to set or clear the WO[n+3] output value when the timer/counter is not running.
Bit 2 – LCMP2OV Low byte Compare 2 Output Value
See LCMP0OV.
Bit 1 – LCMP1OV Low byte Compare 1 Output Value
See LCMP0OV.
Bit 0 – LCMP0OV Low byte Compare 0 Output Value
The LCMPnOV bit allows direct access to the output compare value of the waveform generator when the timer/
counter is not enabled. This is used to set or clear the WOn output value when the timer/counter is not running.
Note:
1. When the output is connected to the pad, overriding these bits will not work unless the xCMPnEN bits in the
TCAn.CTRLB register have been set. If the output is connected to CCL, the xCMPnEN bits in the
TCAn.CTRLB register are bypassed.
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TCA - 16-bit Timer/Counter Type A
20.7.4
Control D - Split Mode
Name:
Offset:
Reset:
Property:
Bit
7
CTRLD
0x03
0x00
-
6
5
4
3
Access
Reset
2
1
0
SPLITM
R/W
0
Bit 0 – SPLITM Enable Split Mode
This bit sets the timer/counter in Split mode operation and will work as two 8-bit timer/counters. The register map will
change compared to the normal 16-bit mode.
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TCA - 16-bit Timer/Counter Type A
20.7.5
Control Register E Clear - Split Mode
Name:
Offset:
Reset:
Property:
CTRLECLR
0x04
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to clear individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
4
3
2
CMD[1:0]
Access
Reset
R/W
0
R/W
0
1
0
CMDEN[1:0]
R/W
R/W
0
0
Bits 3:2 – CMD[1:0] Command
This bit field is used for software control of restart and reset of the timer/counter. The command bit field is always
read as ‘0’.
Value
Name
Description
0x0
NONE
No command
0x1
Reserved
0x2
RESTART
Force restart
0x3
RESET
Force hard Reset (ignored if the timer/counter is enabled)
Bits 1:0 – CMDEN[1:0] Command Enable
This bit field configures what timer/counters the command given by the CMD-bits will be applied to.
Value
Name
Description
0x0
NONE None
0x1
Reserved
0x2
Reserved
0x3
BOTH
Command (CMD) will be applied to both low byte and high byte timer/counter
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20.7.6
Control Register E Set - Split Mode
Name:
Offset:
Reset:
Property:
CTRLESET
0x05
0x00
-
Use this register instead of a Read-Modify-Write (RMW) to set individual bits by writing a ‘1’ to its bit location.
Bit
7
6
5
4
3
2
CMD[1:0]
Access
Reset
R/W
0
R/W
0
1
0
CMDEN[1:0]
R/W
R/W
0
0
Bits 3:2 – CMD[1:0] Command
This bit field is used for software control of restart and reset of the timer/counter. The command bit field is always
read as ‘0’. The CMD bit field must be used together with the Command Enable (CMDEN) bits. Using the RESET
command requires that both low byte and high byte timer/counter are selected with CMDEN.
Value
Name
Description
0x0
NONE
No command
0x1
Reserved
0x2
RESTART
Force restart
0x3
RESET
Force hard Reset (ignored if the timer/counter is enabled)
Bits 1:0 – CMDEN[1:0] Command Enable
This bit field configures what timer/counters the command given by the CMD-bits will be applied to.
Value
Name
Description
0x0
NONE None
0x1
Reserved
0x2
Reserved
0x3
BOTH
Command (CMD) will be applied to both low byte and high byte timer/counter
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TCA - 16-bit Timer/Counter Type A
20.7.7
Interrupt Control Register - Split Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
INTCTRL
0x0A
0x00
-
6
LCMP2
R/W
0
5
LCMP1
R/W
0
4
LCMP0
R/W
0
3
2
1
HUNF
R/W
0
0
LUNF
R/W
0
Bit 6 – LCMP2 Low byte Compare Channel 2 Interrupt Enable
See LCMP0.
Bit 5 – LCMP1 Low byte Compare Channel 1 Interrupt Enable
See LCMP0.
Bit 4 – LCMP0 Low byte Compare Channel 0 Interrupt Enable
Writing the LCMPn bit to ‘1’ enables the low byte Compare Channel n interrupt.
Bit 1 – HUNF High byte Underflow Interrupt Enable
Writing the HUNF bit to ‘1’ enables the high byte underflow interrupt.
Bit 0 – LUNF Low byte Underflow Interrupt Enable
Writing the LUNF bit to ‘1’ enables the low byte underflow interrupt.
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20.7.8
Interrupt Flag Register - Split Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
INTFLAGS
0x0B
0x00
-
6
LCMP2
R/W
0
5
LCMP1
R/W
0
4
LCMP0
R/W
0
3
2
1
HUNF
R/W
0
0
LUNF
R/W
0
Bit 6 – LCMP2 Low byte Compare Channel 2 Interrupt Flag
See LCMP0 flag description.
Bit 5 – LCMP1 Low byte Compare Channel 1 Interrupt Flag
See LCMP0 flag description.
Bit 4 – LCMP0 Low byte Compare Channel 0 Interrupt Flag
The Low byte Compare Interrupt (LCMPn) flag is set on a compare match on the corresponding compare channel in
the low byte timer.
For all modes of operation, the LCMPn flag will be set when a compare match occurs between the Low Byte Timer
Counter (TCAn.LCNT) register and the corresponding Compare n (TCAn.LCMPn) register. The LCMPn flag will not
be cleared automatically and has to be cleared by software. This is done by writing a ‘1’ to its bit location.
Bit 1 – HUNF High byte Underflow Interrupt Flag
This flag is set on a high byte timer BOTTOM (underflow) condition. HUNF is not automatically cleared and needs to
be cleared by software. This is done by writing a ‘1’ to its bit location.
Bit 0 – LUNF Low byte Underflow Interrupt Flag
This flag is set on a low byte timer BOTTOM (underflow) condition. LUNF is not automatically cleared and needs to
be cleared by software. This is done by writing a ‘1’ to its bit location.
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TCA - 16-bit Timer/Counter Type A
20.7.9
Debug Control Register - Split Mode
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x0E
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Run in Debug
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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TCA - 16-bit Timer/Counter Type A
20.7.10 Low Byte Timer Counter Register - Split Mode
Name:
Offset:
Reset:
Property:
LCNT
0x20
0x00
-
The TCAn.LCNT register contains the counter value for the low byte timer. CPU and UPDI write access has priority
over count, clear or reload of the counter.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
LCNT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – LCNT[7:0] Counter Value for Low Byte Timer
This bit field defines the counter value of the low byte timer.
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TCA - 16-bit Timer/Counter Type A
20.7.11 High Byte Timer Counter Register - Split Mode
Name:
Offset:
Reset:
Property:
HCNT
0x21
0x00
-
The TCAn.HCNT register contains the counter value for the high byte timer. CPU and UPDI write access has priority
over count, clear or reload of the counter.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
HCNT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – HCNT[7:0] Counter Value for High Byte Timer
This bit field defines the counter value in high byte timer.
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TCA - 16-bit Timer/Counter Type A
20.7.12 Low Byte Timer Period Register - Split Mode
Name:
Offset:
Reset:
Property:
LPER
0x26
0xFF
-
The TCAn.LPER register contains the TOP value for the low byte timer.
Bit
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
LPER[7:0]
Access
Reset
R/W
1
R/W
1
R/W
1
R/W
1
Bits 7:0 – LPER[7:0] Period Value Low Byte Timer
This bit field holds the TOP value for the low byte timer.
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TCA - 16-bit Timer/Counter Type A
20.7.13 High Byte Period Register - Split Mode
Name:
Offset:
Reset:
Property:
HPER
0x27
0xFF
-
The TCAn.HPER register contains the TOP value for the high byte timer.
Bit
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
HPER[7:0]
Access
Reset
R/W
1
R/W
1
R/W
1
R/W
1
Bits 7:0 – HPER[7:0] Period Value High Byte Timer
This bit field holds the TOP value for the high byte timer.
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TCA - 16-bit Timer/Counter Type A
20.7.14 Compare Register n For Low Byte Timer - Split Mode
Name:
Offset:
Reset:
Property:
LCMPn
0x28 + n*0x02 [n=0..2]
0x00
-
The TCAn.LCMPn register represents the compare value of Compare Channel n for the low byte timer. This register
is continuously compared to the counter value of the low byte timer, TCAn.LCNT. Normally, the outputs from the
comparators are then used to generate waveforms.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
LCMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – LCMP[7:0] Compare Value of Channel n
This bit field holds the compare value of channel n that is compared to TCAn.LCNT.
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20.7.15 High Byte Compare Register n - Split Mode
Name:
Offset:
Reset:
Property:
HCMPn
0x29 + n*0x02 [n=0..2]
0x00
-
The TCAn.HCMPn register represents the compare value of Compare Channel n for the high byte timer. This register
is continuously compared to the counter value of the high byte timer, TCAn.HCNT. Normally, the outputs from the
comparators are then used to generate waveforms.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
HCMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – HCMP[7:0] Compare Value of Channel n
This bit field holds the compare value of channel n that is compared to TCAn.HCNT.
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TCB - 16-Bit Timer/Counter Type B
21.
TCB - 16-Bit Timer/Counter Type B
21.1
Features
•
•
•
21.2
16-Bit Counter Operation Modes:
– Periodic interrupt
– Time-out check
– Input capture
• On event
• Frequency measurement
• Pulse-width measurement
• Frequency and pulse-width measurement
– Single-shot
– 8-bit Pulse-Width Modulation (PWM)
Noise Canceler on Event Input
Synchronize Operation with TCAn
Overview
The capabilities of the 16-bit Timer/Counter type B (TCB) include frequency and waveform generation and input
capture on event with time and frequency measurement of digital signals. The TCB consists of a base counter and
control logic that can be set in one of eight different modes, each mode providing unique functionality. The base
counter is clocked by the peripheral clock with optional prescaling.
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TCB - 16-Bit Timer/Counter Type B
21.2.1
Block Diagram
Figure 21-1. Timer/Counter Type B Block
Clock Select
CTRLA
Mode
CTRLB
EVCTRL
Event Action
Count
Counter
CNT
Events
Control
Logic
Clear
CAPT
(Interrupt Request
and Events)
BOTTOM
=0
CCMP
=
Waveform
Generation
Match
WO
The timer/counter can be clocked from the Peripheral Clock (CLK_PER) or a 16-bit Timer/Counter type A
(CLK_TCAn).
Figure 21-2. Timer/Counter Clock Logic
CTRLA
CLK_PER
DIV2
CLK_TCB
CNT
CLK_TCAn
Control
Logic
Events
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TCB - 16-Bit Timer/Counter Type B
The Clock Select (CLKSEL) bit field in the Control A (TCBn.CTRLA) register selects one of the prescaler outputs
directly as the clock (CLK_TCB) input.
Setting the timer/counter to use the clock from a TCAn allows the timer/counter to run in sync with that TCAn.
By using the EVSYS, any event source, such as an external clock signal on any I/O pin, may be used as a control
logic input. When an event action controlled operation is used, the clock selection must be set to use an event
channel as the counter input.
21.2.2
Signal Description
Signal
Description
Type
WO
Digital Asynchronous Output
Waveform Output
21.3
Functional Description
21.3.1
Definitions
The following definitions are used throughout the documentation:
Table 21-1. Timer/Counter Definitions
Name
Description
BOTTOM
The counter reaches BOTTOM when it becomes 0x0000
MAX
The counter reaches the maximum when it becomes 0xFFFF
TOP
The counter reaches TOP when it becomes equal to the highest value in the count sequence
CNT
Count (TCBn.CNT) register value
CCMP
Capture/Compare (TCBn.CCMP) register value
Note: In general, the term ‘timer’ is used when the timer/counter is counting periodic clock ticks. The term ‘counter’
is used when the input signal has sporadic or irregular ticks.
21.3.2
Initialization
By default, the TCB is in Periodic Interrupt mode. Follow these steps to start using it:
1. Write a TOP value to the Compare/Capture (TCBn.CCMP) register.
2. Optional: Write the Compare/Capture Output Enable (CCMPEN) bit in the Control B (TCBn.CTRLB) register to
‘1’. This will make the waveform output available on the corresponding pin, overriding the value in the
corresponding PORT output register.
3. Enable the counter by writing a ‘1’ to the ENABLE bit in the Control A (TCBn.CTRLA) register.
The counter will start counting clock ticks according to the prescaler setting in the Clock Select (CLKSEL) bit
field in the Control A (TCBn.CTRLA) register.
4. The counter value can be read from the Count (TCBn.CNT) register. The peripheral will generate a CAPT
interrupt and event when the CNT value reaches TOP.
4.1.
If the Compare/Capture register is modified to a value lower than the current Count register, the
peripheral will count to MAX and wrap around.
21.3.3
Operation
21.3.3.1 Modes
The timer can be configured to run in one of the eight different modes described in the sections below. The event
pulse needs to be longer than one system clock cycle to ensure edge detection.
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TCB - 16-Bit Timer/Counter Type B
21.3.3.1.1 Periodic Interrupt Mode
In the Periodic Interrupt mode, the counter counts to the capture value and restarts from BOTTOM. A CAPT interrupt
and event is generated when the counter is equal to TOP. If TOP is updated to a value lower than count upon
reaching MAX, the counter restarts from BOTTOM.
Figure 21-3. Periodic Interrupt Mode
CAPT
(Interrupt Request
MAX
and Event)
TOP
CNT
BOTTOM
TOP changed to
a value lower than CNT
CNT set to BOTTOM
21.3.3.1.2 Time-Out Check Mode
In the Time-Out Check mode, the peripheral starts counting on the first signal edge and stops on the next signal edge
detected on the event input channel. Start or Stop edge is determined by the Event Edge (EDGE) bit in the Event
Control (TCBn.EVCTRL) register. If the Count (TCBn.CNT) register reaches TOP before the second edge, a CAPT
interrupt and event will be generated. In Freeze state, after a Stop edge is detected, the counter will restart on a new
Start edge. If TOP is updated to a value lower than the Count (TCBn.CNT) register upon reaching MAX the counter
restarts from BOTTOM. Reading the Count (TCBn.CNT) register or Compare/Capture (TCBn.CCMP) register, or
writing the Run (RUN) bit in the Status (TCBn.STATUS) register in Freeze state will have no effect.
This mode requires TCB to be configured as an event user and is explained in the Events section.
Figure 21-4. Time-Out Check Mode
Event Input
CAPT
(Interrupt Request
and Event)
Event Detector
MAX
TOP
CNT
BOTTOM
TOP changed to a value lower
than CNT
CNT set to
BOTTOM
21.3.3.1.3 Input Capture on Event Mode
In the Input Capture on Event mode, the counter will count from BOTTOM to MAX continuously. When an event is
detected, the Count (TCBn.CNT) register value is transferred to the Compare/Capture (TCBn.CCMP) register, and a
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TCB - 16-Bit Timer/Counter Type B
CAPT interrupt and event is generated. The Event edge detector that can be configured to trigger a capture on either
rising or falling edges.
This mode requires TCB to be configured as an event user and is explained in the Events section.
The figure below shows the input capture unit configured to capture on the falling edge of the event input signal. The
CAPT Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register has
been read.
Figure 21-5. Input Capture on Event
Event Input
CAPT
(Interrupt Request
and Event)
Event Detector
MAX
CNT
BOTTOM
Copy CNT to
CCMP and CAPT
CNT set to
BOTTOM
Copy CNT to
CCMP and CAPT
Important: It is recommended to write 0x0000 to the Count (TCBn.CNT) register when entering this
mode from any other mode.
21.3.3.1.4 Input Capture Frequency Measurement Mode
In the Input Capture Frequency Measurement mode, the TCB captures the counter value and restarts on either a
positive or negative edge of the event input signal.
The CAPT Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register
has been read.
The figure below illustrates this mode when configured to act on the rising edge.
This mode requires TCB to be configured as an event user and is explained in the Events section.
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TCB - 16-Bit Timer/Counter Type B
Figure 21-6. Input Capture Frequency Measurement
CAPT
(Interrupt Request
Event Input
and Event)
Event Detector
MAX
CNT
BOTTOM
CNT set to
BOTTOM
Copy CNT to CCMP,
CAPT and restart
Copy CNT to CCMP,
CAPT and restart
21.3.3.1.5 Input Capture Pulse-Width Measurement Mode
In the Input Capture Pulse-Width Measurement mode, the input capture pulse-width measurement will restart the
counter on a positive edge and capture on the next falling edge before an interrupt request is generated. The CAPT
Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register has been
read. The timer will automatically switch between rising and falling edge detection, but a minimum edge separation of
two clock cycles is required for correct behavior.
This mode requires TCB to be configured as an event user and is explained in the Events section.
Figure 21-7. Input Capture Pulse-Width Measurement
CAPT
Event Input
(Interrupt Request
and Event)
Edge Detector
MAX
CNT
BOTTOM
Start counter
Copy CNT to
CCMP and CAPT
Restart
counter
Copy CNT to
CCMP and CAPT
CNT set to
BOTTOM
21.3.3.1.6 Input Capture Frequency and Pulse-Width Measurement Mode
In the Input Capture Frequency and Pulse-Width Measurement mode, the timer will start counting when a positive
edge is detected on the event input signal. The count value is captured on the following falling edge. The counter
stops when the second rising edge of the event input signal is detected, which will set the interrupt flag.
The CAPT Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register
has been read, and the timer/counter is ready for a new capture sequence. Therefore, the Count (TCBn.CNT)
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TCB - 16-Bit Timer/Counter Type B
register must be read before the Compare/Capture (TCBn.CCMP) register since it is reset to BOTTOM at the next
positive edge of the event input signal.
This mode requires TCB to be configured as an event user and is explained in the Events section.
Figure 21-8. Input Capture Frequency and Pulse-Width Measurement
Ignored until CPU
reads CCMP register
Trigger next capture
sequence
CAPT
(Interrupt Request
Event Input
and Event)
Event Detector
MAX
CNT
BOTTOM
Start
counter
Copy CNT to
CCMP
Stop counter and
CAPT
CPU reads the
CCMP register
21.3.3.1.7 Single-Shot Mode
The Single-Shot mode can be used to generate a pulse with a duration defined by the Compare (TCBn.CCMP)
register every time a rising or falling edge is observed on a connected event channel.
When the counter is stopped, the output pin is driven to low. If an event is detected on the connected event channel,
the timer will reset and start counting from BOTTOM to TOP while driving its output high. The RUN bit in the Status
(TCBn.STATUS) register can be read to see if the counter is counting or not. When the Counter register reaches the
CCMP register value, the counter will stop, and the output pin will go low for at least one prescaler cycle. A new event
arriving during this time will be ignored. There is a two clock-cycle delay from when the event is received until the
output is set high. When the EDGE bit of the TCB.EVCTRL register is written to ‘1’, any edge can trigger the start of
the counter. If the EDGE bit is ‘0’, only positive edges trigger the start.
The counter will start counting as soon as the module is enabled, even without triggering an event. This is prevented
by writing TOP to the Counter register. Similar behavior is seen if the Event Edge (EDGE) bit in the Event Control
(TCBn.EVCTRL) register is ‘1’ while the module is enabled. Writing TOP to the Counter register prevents this as well.
If the Event Asynchronous (ASYNC) bit in the Control B (TCBn.CTRLB) register is written to ‘1’, the timer will react
asynchronously to an incoming event. An edge on the event will immediately cause the output signal to be set. The
counter will still start counting two clock cycles after the event is received.
This mode requires TCB to be configured as an event user and is explained in the Events section.
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TCB - 16-Bit Timer/Counter Type B
Figure 21-9. Single-Shot Mode
Ignored
Ignored
CAPT
(Interrupt Request
and Event)
Edge Detector
TOP
CNT
BOTTOM
Output
Event starts
counter
Counter reaches
TOP value
Event starts
counter
Counter reaches
TOP value
21.3.3.1.8 8-Bit PWM Mode
The TCB can be configured to run in 8-bit PWM mode, where each of the register pairs in the 16-bit Compare/
Capture (TCBn.CCMPH and TCBn.CCMPL) register are used as individual Compare registers. The period (T) is
controlled by CCMPL, while CCMPH controls the duty cycle of the waveform. The counter will continuously count
from BOTTOM to CCMPL, and the output will be set at BOTTOM and cleared when the counter reaches CCMPH.
CCMPH is the number of cycles for which the output will be driven high. CCMPL+1 is the period of the output pulse.
Figure 21-10. 8-Bit PWM Mode
Period (T)
CCMPH=BOTTOM
CCMPH=TOP
CCMPH>TOP
CAPT
(Interrupt Request
and Event)
MAX
TOP
CNT
CCMPL
CCMPH
BOTTOM
Output
21.3.3.2 Output
Timer synchronization and output logic level are dependent on the selected Timer Mode (CNTMODE) bit field in
Control B (TCBn.CTRLB) register. In Single-Shot mode, the timer/counter can be configured so that the signal
generation happens asynchronously to an incoming event (ASYNC = 1 in TCBn.CTRLB). The output signal is then
set immediately at the incoming event instead of being synchronized to the TCB clock. Even though the output is
immediately set, it will take two to three CLK_TCB cycles before the counter starts counting.
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TCB - 16-Bit Timer/Counter Type B
Writing the Compare/Capture Output Enable (CCMPEN) bit in TCBn.CTRLB to ‘1’ enables the waveform output,
which will make the waveform output available on the corresponding pin, overriding the value in the corresponding
PORT output register.
The different configurations and their impact on the output are listed in the table below.
Table 21-2. Output Configuration
CCMPEN
CNTMODE
ASYNC
0
The output is high when
the counter starts, and the
output is low when the
counter stops
1
The output is high when
the event arrives, and the
output is low when the
counter stops
Single-Shot mode
1
0
Output
8-bit PWM mode
Not applicable
8-bit PWM mode
Other modes
Not applicable
The output initial level sets
the CCMPINIT bit in the
TCBn.CTRLB register
Not applicable
Not applicable
No output
It is not recommended to change modes while the peripheral is enabled, as this can produce an unpredictable output.
There is a possibility that an interrupt flag is set during the timer configuration. It is recommended to clear the Timer/
Counter Interrupt Flags (TCBn.INTFLAGS) register after configuring the peripheral.
21.3.3.3 Noise Canceler
The Noise Canceler improves noise immunity by using a simple digital filter scheme. When the Noise Filter (FILTER)
bit in the Event Control (TCBn.EVCTRL) register is enabled, the peripheral monitors the event channel and keeps a
record of the last four observed samples. If four consecutive samples are equal, the input is considered to be stable,
and the signal is fed to the edge detector.
When enabled, the Noise Canceler introduces an additional delay of four system clock cycles between a change
applied to the input and the update of the Input Compare register.
The Noise Canceler uses the system clock and is, therefore, not affected by the prescaler.
21.3.3.4 Synchronized with Timer/Counter Type A
The TCB can be configured to use the clock (CLK_TCA) of a Timer/Counter type A (TCAn) by writing to the Clock
Select (CLKSEL) bit field in the Control A register (TCBn.CTRLA). In this setting, the TCB will count on the same
clock source as selected in TCAn.
When the Synchronize Update (SYNCUPD) bit in the Control A (TCBn.CTRLA) register is written to ‘1’, the TCB
counter will restart when the TCAn counter restarts.
21.3.4
Events
The TCB can generate the events described in the following table:
Table 21-3. Event Generators in TCB
Generator Name
Peripheral
TCBn
Event
Description
CAPT CAPT flag set
Event Type
Generating Clock Domain
Pulse
CLK_PER
Length of Event
One CLK_PER period
The conditions for generating the CAPT event are identical to those that will raise the corresponding interrupt flag in
the Timer/Counter Interrupt Flags (TCBn.INTFLAGS) register. Refer to the Event System section for more details
regarding event users and Event System configuration.
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TCB - 16-Bit Timer/Counter Type B
The TCB can receive the events described in the following table:
Table 21-4. Event Users and Available Event Actions in TCB
User Name
Description
Peripheral Input
Input Detection Async/Sync
Time-Out Check Count mode
Input Capture on Event Count mode
Input Capture Frequency Measurement Count mode
TCBn
CAPT Input Capture Pulse-Width Measurement Count mode
Edge
Sync
Input Capture Frequency and Pulse-Width Measurement
Count mode
Single-Shot Count mode
Both
If the Capture Event Input Enable (CAPTEI) bit in the Event Control (TCBn.EVCTRL) register is written to ‘1’,
incoming events will result in an event action as defined by the Event Edge (EDGE) bit in the Event Control
(TCBn.EVCTRL) register and the Timer Mode (CNTMODE) bit field in Control B (TCBn.CTRLB) register. The event
needs to last for at least one CLK_PER cycle to be recognized.
If the Asynchronous mode is enabled for Single-Shot mode, the event is edge-triggered and will capture changes on
the event input shorter than one system clock cycle.
21.3.5
Interrupts
Table 21-5. Available Interrupt Vectors and Sources
Name Vector Description Conditions
CAPT TCB interrupt
Depending on the operating mode. See the description of the CAPT bit in the
TCBn.INTFLAG register.
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
21.3.6
Sleep Mode Operation
TCBn is, by default, disabled in Standby sleep mode. It will be halted as soon as the sleep mode is entered.
The module can stay fully operational in the Standby sleep mode if the Run Standby (RUNSTDBY) bit in the
TCBn.CTRLA register is written to ‘1’.
All operations are halted in Power-Down sleep mode.
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TCB - 16-Bit Timer/Counter Type B
21.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
...
0x03
0x04
0x05
0x06
0x07
0x08
0x09
CTRLA
CTRLB
EVCTRL
INTCTRL
INTFLAGS
STATUS
DBGCTRL
TEMP
0x0A
CNT
0x0C
CCMP
21.5
7
6
5
4
3
7:0
7:0
RUNSTDBY
ASYNC
CCMPINIT
SYNCUPD
CCMPEN
7:0
7:0
7:0
7:0
7:0
7:0
7:0
15:8
7:0
15:8
FILTER
2
1
CLKSEL[1:0]
CNTMODE[2:0]
0
ENABLE
Reserved
EDGE
CAPTEI
CAPT
CAPT
RUN
DBGRUN
TEMP[7:0]
CNT[7:0]
CNT[15:8]
CCMP[7:0]
CCMP[15:8]
Register Description
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TCB - 16-Bit Timer/Counter Type B
21.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
Access
Reset
CTRLA
0x00
0x00
-
6
RUNSTDBY
R/W
0
5
4
SYNCUPD
R/W
0
3
2
1
CLKSEL[1:0]
R/W
R/W
0
0
0
ENABLE
R/W
0
Bit 6 – RUNSTDBY Run in Standby
Writing a ‘1’ to this bit will enable the peripheral to run in Standby Sleep mode. Not applicable when CLKSEL is set to
0x2 (CLK_TCA).
Bit 4 – SYNCUPD Synchronize Update
When this bit is written to ‘1’, the TCB will restart whenever TCA0 is restarted or overflows. This can be used to
synchronize capture with the PWM period.
Bits 2:1 – CLKSEL[1:0] Clock Select
Writing these bits selects the clock source for this peripheral.
Value
Name
Description
0x0
0x1
0x3
0x4
CLKDIV1
CLKDIV2
CLKTCA
-
CLK_PER
CLK_PER/DIV2
Use TCA_CLK from TCA0
Reserved
Bit 0 – ENABLE Enable
Writing this bit to ‘1’ enables the Timer/Counter type B peripheral.
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TCB - 16-Bit Timer/Counter Type B
21.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLB
0x01
0x00
-
6
ASYNC
R/W
0
5
CCMPINIT
R/W
0
4
CCMPEN
R/W
0
3
2
R/W
0
1
CNTMODE[2:0]
R/W
0
0
R/W
0
Bit 6 – ASYNC Asynchronous Enable
Writing this bit to ‘1’ will allow asynchronous updates of the TCB output signal in Single-Shot mode.
Value
Description
0
The output will go HIGH when the counter starts after synchronization
1
The output will go HIGH when an event arrives
Bit 5 – CCMPINIT Compare/Capture Pin Initial Value
This bit is used to set the initial output value of the pin when a pin output is used. This bit has no effect in 8-bit PWM
mode and Single-Shot mode.
Value
Description
0
Initial pin state is LOW
1
Initial pin state is HIGH
Bit 4 – CCMPEN Compare/Capture Output Enable
Writing this bit to ‘1’ enables the waveform output. This will make the waveform output available on the corresponding
pin, overriding the value in the corresponding PORT output register. The corresponding pin direction must be
configured as an output in the PORT peripheral.
Value
Description
0
Waveform output is not enabled on the corresponding pin
1
Waveform output will override the output value of the corresponding pin
Bits 2:0 – CNTMODE[2:0] Timer Mode
Writing these bits selects the Timer mode.
Value
Name
Description
0x0
INT
Periodic Interrupt mode
0x1
TIMEOUT
Time-out Check mode
0x2
CAPT
Input Capture on Event mode
0x3
FRQ
Input Capture Frequency Measurement mode
0x4
PW
Input Capture Pulse-Width Measurement mode
0x5
FRQPW
Input Capture Frequency and Pulse-Width Measurement mode
0x6
SINGLE
Single-Shot mode
0x7
PWM8
8-Bit PWM mode
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TCB - 16-Bit Timer/Counter Type B
21.5.3
Event Control
Name:
Offset:
Reset:
Property:
Bit
EVCTRL
0x04
0x00
-
7
Access
Reset
6
FILTER
R/W
0
5
4
EDGE
R/W
0
3
2
1
0
CAPTEI
R/W
0
Bit 6 – FILTER Input Capture Noise Cancellation Filter
Writing this bit to ‘1’ enables the Input Capture Noise Cancellation unit.
Bit 4 – EDGE Event Edge
This bit is used to select the event edge. The effect of this bit is dependent on the selected Count Mode (CNTMODE)
bit field in TCBn.CTRLB. “—” means that an event or edge does not affect this mode.
Count Mode
Periodic Interrupt mode
Timeout Check mode
Input Capture on Event mode
Input Capture Frequency
Measurement mode
Input Capture Pulse-Width
Measurement mode
EDGE Positive Edge
Negative Edge
0
1
0
1
0
1
—
—
Stop counter
Start counter
—
Input Capture, interrupt
0
1
0
1
0
Input Capture Frequency and PulseWidth Measurement mode
1
Single-Shot mode
8-Bit PWM mode
0
1
0
1
—
—
Start counter
Stop counter
Input Capture, interrupt
—
Input Capture, clear and restart
counter, interrupt
—
Input Capture, clear and restart
counter, interrupt
Clear and restart counter
Input Capture, interrupt
Input Capture, interrupt
Clear and restart counter
• On the 1st Positive: Clear and restart counter
• On the following Negative: Input Capture
• On the 2nd Positive: Stop counter, interrupt
• On the 1st Negative: Clear and restart counter
• On the following Positive: Input Capture
• On the 2nd Negative: Stop counter, interrupt
Start counter
—
Start counter
Start counter
—
—
—
—
—
Bit 0 – CAPTEI Capture Event Input Enable
Writing this bit to ‘1’ enables the input capture event.
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TCB - 16-Bit Timer/Counter Type B
21.5.4
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x05
0x00
-
6
5
4
3
Access
Reset
2
1
0
CAPT
R/W
0
Bit 0 – CAPT Capture Interrupt Enable
Writing this bit to ‘1’ enables interrupt on capture.
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TCB - 16-Bit Timer/Counter Type B
21.5.5
Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
INTFLAGS
0x06
0x00
-
7
6
5
4
3
2
1
0
CAPT
R/W
0
Access
Reset
Bit 0 – CAPT Capture Interrupt Flag
This bit is set when a capture interrupt occurs. The interrupt conditions are dependent on the Counter Mode
(CNTMODE) bit field in the Control B (TCBn.CTRLB) register.
This bit is cleared by writing a ‘1’ to it or when the Capture register is read in Capture mode.
Table 21-6. Interrupt Sources Set Conditions by Counter Mode
Counter Mode
Interrupt Set Condition
TOP
Value
CAPT
Periodic Interrupt mode
Timeout Check mode
Single-Shot mode
Set when the counter reaches TOP
Set when the counter reaches TOP
Set when the counter reaches TOP
CCMP
CNT == TOP
Input Capture Frequency
Measurement mode
Set on edge when the Capture register is
loaded, and the counter restarts; the flag
clears when the capture is read
Set when an event occurs and the Capture
register is loaded; the flag clears when the
capture is read
-Set on edge when the Capture register is
Input Capture Pulse-Width
loaded; the previous edge initialized the count;
Measurement mode
the flag clears when the capture is read
Input Capture Frequency Set on the second edge (positive or negative)
and Pulse-Width
when the counter is stopped; the flag clears
Measurement mode
when the capture is read
8-Bit PWM mode
Set when the counter reaches CCML
CCML
On Event, copy CNT to
CCMP, and restart
counting (CNT ==
BOTTOM)
Input Capture on Event
mode
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On Event, copy CNT to
CCMP, and continue
counting
CNT == CCML
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TCB - 16-Bit Timer/Counter Type B
21.5.6
Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x07
0x00
-
6
5
4
3
2
1
0
RUN
R
0
Access
Reset
Bit 0 – RUN Run
When the counter is running, this bit is set to ‘1’. When the counter is stopped, this bit is cleared to ‘0’.
The bit is read-only and cannot be set by UPDI.
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TCB - 16-Bit Timer/Counter Type B
21.5.7
Debug Control
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x08
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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TCB - 16-Bit Timer/Counter Type B
21.5.8
Temporary Value
Name:
Offset:
Reset:
Property:
TEMP
0x09
0x00
-
The Temporary register is used by the CPU for 16-bit single-cycle access to the 16-bit registers of this peripheral. The
register is common for all the 16-bit registers of this peripheral and can be read and written by software. For more
details on reading and writing 16-bit registers, refer to Accessing 16-Bit Registers in the AVR CPU section.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
TEMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TEMP[7:0] Temporary Value
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TCB - 16-Bit Timer/Counter Type B
21.5.9
Count
Name:
Offset:
Reset:
Property:
CNT
0x0A
0x00
-
The TCBn.CNTL and TCBn.CNTH register pair represents the 16-bit value TCBn.CNT. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
CPU and UPDI write access has priority over internal updates of the register.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CNT[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
CNT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CNT[15:8] Count Value High
These bits hold the MSB of the 16-bit Counter register.
Bits 7:0 – CNT[7:0] Count Value Low
These bits hold the LSB of the 16-bit Counter register.
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TCB - 16-Bit Timer/Counter Type B
21.5.10 Capture/Compare
Name:
Offset:
Reset:
Property:
CCMP
0x0C
0x00
-
The TCBn.CCMPL and TCBn.CCMPH register pair represents the 16-bit value TCBn.CCMP. The low byte [7:0]
(suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
This register has different functions depending on the mode of operation:
• For Capture operation, these registers contain the captured value of the counter at the time the capture occurs
• In Periodic Interrupt/Time-Out and Single-Shot mode, this register acts as the TOP value
• In 8-bit PWM mode, TCBn.CCMPL and TCBn.CCMPH act as two independent registers: The period of the
waveform is controlled by CCMPL, while CCMPH controls the duty cycle.
Bit
Access
Reset
Bit
15
14
13
R/W
0
R/W
0
R/W
0
7
6
5
12
11
CCMP[15:8]
R/W
R/W
0
0
4
10
9
8
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CCMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CCMP[15:8] Capture/Compare Value High Byte
These bits hold the MSB of the 16-bit compare, capture, and top value.
Bits 7:0 – CCMP[7:0] Capture/Compare Value Low Byte
These bits hold the LSB of the 16-bit compare, capture, and top value.
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TCD - 12-Bit Timer/Counter Type D
22.
TCD - 12-Bit Timer/Counter Type D
22.1
Features
•
•
•
•
•
•
•
•
•
22.2
12-bit Timer/Counter
Programmable Prescaler
Double-Buffered Compare Registers
Waveform Generation:
– One Ramp mode
– Two Ramp mode
– Four Ramp mode
– Dual Slope mode
Two Separate Input Channels
Software and Input Based Capture
Programmable Filter for Input Events
Conditional Waveform Generation on External Events:
– Fault handling
– Input blanking
– Overload protection
– Fast emergency stop by hardware
Half-Bridge and Full-Bridge Output Support
Overview
The Timer/Counter type D (TCD) is a high-performance waveform generator that consists of an asynchronous
counter, a prescaler, and compare, capture and control logic.
The TCD contains a counter that can run on a clock which is asynchronous to the peripheral clock. It contains
compare logic that generates two independent outputs with optional dead time. It is connected to the Event System
for capture and deterministic Fault control. The timer/counter can generate interrupts and events on compare match
and overflow.
This device provides one instance of the TCD peripheral, TCD0.
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TCD - 12-Bit Timer/Counter Type D
22.2.1
Block Diagram
Figure 22-1. Timer/Counter Block Diagram
Peripheral
clock
domain
TCD clock
domain
Counter and
Fractional
Accumulator
CMPASET
CMPASET_
BUF
=
CMPACLR
CMPACLR_
BUF
=
Event Input A
CAPTUREA_
BUF
CMPBSET
CMPBSET_
BUF
=
CMPBCLR_
BUF
=
Waveform
generator A
CLR A
CMPASET/PROGEV
(Event)
WOA
PROGEV (Event)
TRIGA (INT Req.)
WOC
Compare/Capture
Unit B
SET B
Waveform
generator B
CLR B
Event Input
Logic B
Event Input B
CAPTUREB
SET A
Event Input
Logic A
CAPTUREA
CMPBCLR
Compare/Capture
Unit A
CAPTUREB_
BUF
WOD
CMPBSET/PROGEV
(Event)
WOB
CMPBCLR/PROGEV
(Event)
TRIG OVF (INT Req.)
TRIGB (INT Req.)
The TCD core is asynchronous to the peripheral clock. The timer/counter consists of two compare/capture units,
each with a separate waveform output. There are also two extra waveform outputs which can be equal to the output
from one of the units. For each compare/capture unit, there is a pair of compare registers which are stored in the
respective peripheral registers (TCDn.CMPASET, TCDn.CMPACLR, TCDn.CMPBSET, TCDn.CMPBCLR).
During normal operation, the counter value is continuously compared to the compare registers. This is used to
generate both interrupts and events.
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TCD - 12-Bit Timer/Counter Type D
The TCD can use the input events in ten different input modes, selected separately for the two input events. The
input mode defines how the input events will affect the outputs, and where in the TCD cycle the counter must go
when an event occurs.
The TCD can select between four different clock sources that can be prescaled. There are three different prescalers
with separate controls, as shown below.
Figure 22-2. Clock Selection and Prescalers Overview
CLKSEL
Counter
prescaler
OSCHF
PLL
EXTCLK
CLK_PER
CLK_TCD
Synchronization
prescaler
Counter clock
(CLK_TCD_CNT)
Synchronizer clock
(CLK_TCD_SYNC)
Delay
prescaler (1)
Delay clock
(CLK_TCD_DLY)
1. Used by input blanking/delay event out.
The TCD synchronizer clock is separate from the other module clocks, enabling faster synchronization between the
TCD domain and the I/O domain.
The total prescaling for the counter is:
SYNCPRESC_division_factor × CNTPRESC_division_factor
The delay prescaler is used to prescale the clock used for the input blanking/delayed event output functionality. The
prescaler can be configured independently allowing separate range and accuracy settings from the counter
functionality. The synchronization prescaler and counter prescaler can be configured from the Control A
(TCDn.CTRLA) register, while the delay prescaler can be configured from the Delay Control (TCDn.DLYCTRL)
register.
22.2.2
Signal Description
Signal
Description
Type
WOA
TCD waveform output A
Digital output
WOB
TCD waveform output B
Digital output
WOC
TCD waveform output C
Digital output
WOD
TCD waveform output D
Digital output
22.3
Functional Description
22.3.1
Definitions
The following definitions are used throughout the documentation:
Table 22-1. Timer/Counter Definitions
Name
Description
TCD cycle
The sequence of four states that the counter needs to go through before it has returned to the
same position.
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TCD - 12-Bit Timer/Counter Type D
...........continued
22.3.2
Name
Description
Input blanking
The functionality to ignore an event input for a programmable time in a selectable part of the TCD
cycle.
Asynchronous
output control
Allows the event to override the output instantly when an event occurs. It is used for handling
non-recoverable Faults.
One ramp
The counter is reset to zero once during a TCD cycle.
Two ramp
The counter is reset to zero two times during a TCD cycle.
Four ramp
The counter is reset to zero four times during a TCD cycle.
Dual ramp
The counter counts both up and down between zero and a selected top value during a TCD
cycle.
Input mode
A predefined setting that changes the output characteristics, based on the given input events.
Initialization
To initialize the TCD:
1. Select the clock source and the prescaler from the Control A (TCDn.CTRLA) register.
2. Select the Waveform Generation Mode from the Control B (TCDn.CTRLB) register.
3. Optional: Configure the other static registers to the desired functionality.
4. Write the initial values in the Compare (TCDn.CMPxSET/CLR) registers.
5. Optional: Write the desired values to the other double-buffered registers.
6. Ensure that the Enable Ready (ENRDY) bit in the Status (TCDn.STATUS) register is set to ‘1’.
7.
22.3.3
Enable the TCD by writing a ‘1’ to the ENABLE bit in the Control A (TCDn.CTRLA) register.
Operation
22.3.3.1 Register Synchronization Categories
Most of the I/O registers need to be synchronized to the TCD core clock domain. This is done differently for different
register categories.
Table 22-2. Categorization of Registers
Enable and
Command
Registers
Double-Buffered
Registers
Static Registers
TCDn.CTRLA
(ENABLE bit)
TCDn.DLYCTRL
TCDn.CTRLA(1) (All bits TCDn.STATUS
except ENABLE bit)
TCDn.INTCTRL
TCDn.CTRLE
TCDn.DLYVAL
TCDn.CTRLB
TCDn.CAPTUREA
TCDn.INTFLAGS
TCDn.DITCTRL
TCDn.CTRLC
TCDn.CAPTUREB
TCDn.DITVAL
TCDn.CTRLD
TCDn.DBGCTRL
TCDn.EVCTRLA
TCDn.CMPASET
TCDn.EVCTRLB
TCDn.CMPACLR
TCDn.INPUTCTRLA
TCDn.CMPBSET
TCDn.INPUTCTRLB
TCDn.CMPBCLR
TCDn.FAULTCTRL(2)
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Read-Only Registers
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Normal I/O
Registers
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TCD - 12-Bit Timer/Counter Type D
Notes:
1. The bits in the Control A (TCDn.CTRLA) register are enable-protected, except the ENABLE bit. They can only
be written when ENABLE is written to ‘0’ first.
2.
This register is protected by the Configuration Change Protection Mechanism, requiring a timed write
procedure for changing its value settings.
Enable and Command Registers
Because of the synchronization between the clock domains, it is only possible to change the ENABLE bit in the
Control A (TCDn.CTRLA) register, while the Enable Ready (ENRDY) bit in the Status (TCDn.STATUS) register is ‘1’.
The Control E (TCDn.CTRLE) register is automatically synchronized to the TCD core domain when the TCD is
enabled and as long as no synchronization is ongoing already. Check if the Command Ready (CCMDRDY) bit in
TCDn.STATUS is ‘1’ to ensure that it is possible to issue a new command. TCDn.CTRLE is a strobe register that will
clear itself when the command is sent.
Double-Buffered Registers
The double-buffered registers can be updated in normal I/O writes, while TCD is enabled and no synchronization
between the two clock domains is ongoing. Check that the CMDRDY bit in TCDn.STATUS is ‘1’ to ensure that it is
possible to update the double-buffered registers. The values will be synchronized to the TCD core domain when a
synchronization command is sent or when TCD is enabled.
Table 22-3. Issuing Synchronization Command
Synchronization Issuing Bit
Double Register Update
CTRLC.AUPDATE
Every time the CMPBCLRH register is written, the
synchronization occurs at the end of the TCD cycle.
CTRLE.SYNC (1)
Occurs once, as soon as the SYNC bit is synchronized
with the TDC domain.
CTRLE.SYNCEOC (1)
Occurs once at the end of the next TCD cycle.
Note:
1. If synchronization is already ongoing, the action has no effect.
Static Registers
Static registers cannot be updated while TCD is enabled. Therefore, these registers must be configured before
enabling TCD. To see if TCD is enabled, check if ENABLE in TCDn.CTRLA is read as ‘1’.
Normal I/O and Read-Only Registers
Normal I/O and read-only registers are not constrained by any synchronization between the domains. The read-only
registers inform about synchronization status and values synchronized from the core domain.
22.3.3.2 Waveform Generation Modes
The TCD provides four different Waveform Generation modes controlled by the Waveform Generation Mode
(WGMODE) bit field in the Control B (TCDn.CTRLB) register. The Waveform Generation modes are:
• One Ramp mode
• Two Ramp mode
• Four Ramp mode
• Dual Slope mode
The Waveform Generation modes determine how the counter is counting during a TCD cycle and how the compare
values influence the waveform. A TCD cycle is split into these states:
•
•
•
Dead time WOA (DTA)
On time WOA (OTA)
Dead time WOB (DTB)
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TCD - 12-Bit Timer/Counter Type D
•
On time WOB (OTB)
The Compare A Set (CMPASET), Compare A Clear (CMPACLR), Compare B Set (CMPBSET) and Compare B Clear
(CMPBCLR) compare values define when each state ends and the next begins.
22.3.3.2.1 One Ramp Mode
In One Ramp mode, the TCD counter counts up until it reaches the CMPBCLR value. Then, the TCD cycle is
completed, and the counter restarts from 0x000, beginning a new TCD cycle. The TCD cycle period is:
�TCD_cycle =
CMPBCLR + 1
�CLK_TCD_CNT
Figure 22-3. One Ramp Mode
TCD cycle
Dead time A
Compare
values
On time A
Dead time B
On time B
Counter
value
CMPBCLR
CMPBSET
CMPACLR
CMPASET
WOA
WOB
In the figure above, CMPASET < CMPACLR < CMPBSET < CMPBCLR. In One Ramp mode, this is required to avoid
overlapping outputs during the on time. The figure below is an example where CMPBSET < CMPASET < CMPACLR
< CMPBCLR, which has overlapping outputs during the on time.
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Figure 22-4. One Ramp Mode with CMPBSET < CMPASET
TCD cycle
Dead time A
Compare
values
On time A
On time B
Counter
value
CMPBCLR
CMPACLR
CMPASET
CMPBSET
WOA
WOB
A match with CMPBCLR will always result in all outputs being cleared. If any of the other compare values are bigger
than CMPBCLR, their associated effect will never occur. If the CMPACLR is smaller than the CMPASET value, the
clear value will not have any effect.
22.3.3.2.2 Two Ramp Mode
In Two Ramp mode, the TCD counter counts up until it reaches the CMPACLR value, then it resets and counts up
until it reaches the CMPBCLR value. Then, the TCD cycle is completed, and the counter restarts from 0x000,
beginning a new TCD cycle. The TCD cycle period is given by:
�TCD_cycle =
CMPACLR + 1 + CMPBCLR + 1
�CLK_TCD_CNT
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Figure 22-5. Two Ramp Mode
TCD cycle
Dead time A
On time A
Dead time B
On time B
Counter
value
CMPBCLR
CMPACLR
CMPBSET
CMPASET
WOA
WOB
In the figure above, CMPASET < CMPACLR and CMPBSET < CMPBCLR. This causes the outputs to go high. There
are no restrictions on the CMPASET and CMPACLR compared to the CMPBSET and CMPBCLR values.
In Two Ramp mode, it is not possible to get overlapping outputs without using the override feature. Even if
CMPASET/CMPBSET > CMPACLR/CMPBCLR, the counter resets at CMPACLR/CMPBCLR and will never reach
CMPASET/CMPBSET.
22.3.3.2.3 Four Ramp Mode
In Four Ramp mode, the TCD cycle follows this pattern:
1. A TCD cycle begins with the TCD counter counting up from zero until it reaches the CMPASET value, and
resets to zero.
2. The counter counts up until it reaches the CMPACLR value, and resets to zero.
3. The counter counts up until it reaches the CMPBSET value, and resets to zero.
4. The counter counts up until it reaches the CMPBCLR value, and ends the TCD cycle by resetting to zero.
The TCD cycle period is given by:
�TCD_cycle =
CMPASET + 1 + CMPACLR + 1 + CMPBSET + 1 + CMPBCLR + 1
�CLK_TCD_CNT
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Figure 22-6. Four Ramp Mode
TCD cycle
Dead time A
On time A
Dead time B
On time B
Counter
value
CMPBCLR
CMPACLR
CMPBSET
CMPASET
WOA
WOB
There are no restrictions regarding the compare values, because there are no dependencies between them.
In Four Ramp mode, it is not possible to get overlapping outputs without using the override feature.
22.3.3.2.4 Dual Slope Mode
In Dual Slope mode, a TCD cycle consists of the TCD counter counting down from CMPBCLR value to zero, and up
again to the CMPBCLR value. This gives a TCD cycle period:
2 × CMPBCLR + 1
�CLK_TCD_CNT
The WOA output is set when the TCD counter counts down and matches the CMPASET value. WOA is cleared when
the TCD counter counts up and matches the CMPASET value.
�TCD_cycle =
The WOB output is set when the TCD counter counts up and matches the CMPBSET value. WOB is cleared when
the TCD counter counts down and matches the CMPBSET value.
The outputs will overlap if CMPASET > CMPBSET.
CMPACLR is not used in Dual Slope mode. Writing a value to CMPACLR has no effect.
Figure 22-7. Dual Slope Mode
TCD cycle
On time B
CMPBCLR
Dead
time A
On time A
Dead
time B
On time B
Dead
time A
On time A
Counter
value
CMPBSET
CMPASET
WOA
WOB
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When starting the TCD in Dual Slope mode, the TCD counter starts at the CMPBCLR value and counts down. In the
first cycle, the WOB will not be set until the TCD counter matches the CMPBSET value when counting up.
When the Disable at End of Cycle Strobe (DISEOC) bit in the Control E (TCDn.CTRLE) register is set, the TCD will
automatically be disabled at the end of the TCD cycle.
Figure 22-8. Dual Slope Mode Starting and Stopping
TCD cycle
CMPBCLR
Counter
value
CMPBSET
CMPASET
WOA
WOB
Stop
Start
22.3.3.3 Disabling TCD
Disabling the TCD can be done in two different ways:
1. By writing a ‘0’ to the ENABLE bit in the Control A (TCDn.CTRLA) register. This disables the TCD instantly
when synchronized to the TCD core domain.
2. By writing a ‘1’ to the Disable at End of Cycle Strobe (DISEOC) bit in the Control E (TCDn.CTRLE) register.
This disables the TCD at the end of the TCD cycle.
22.3.3.4 TCD Inputs
The TCD has two inputs connected to the Event System: input A and input B. Each input has a functionality
connected to the corresponding output (WOA and WOB). This functionality is controlled by the Event Control
(TCDn.EVCTRLA and TCDn.EVCTRLB) registers and the Input Control (TCDn.INPUTCTRLA and
TCDn.INPUTCTRLB) registers.
To enable the input events, write a ‘1’ to the Trigger Event Input Enable (TRIGEI) bit in the corresponding Event
Control (TCDn.EVCTRLA or TCDn.EVCTRLB) register. The inputs will be used as a Fault detect by default, but they
can also be used as a capture trigger. To enable a capture trigger, write a ‘1’ to the ACTION bit in the corresponding
Event Control (TCDn.EVCTRLA or TCDn.EVCTRLB) register. To disable Fault detect, the INPUTMODE bit field in
the corresponding Input Control (TCDn.INPUTCTRLA or TCDn.INPUTCTRLB) register must be written to ‘0’.
There are ten different input modes for the Fault detection. The two inputs have the same functionality, except for
input blanking which is only supported by input A. Input blanking is configured by the Delay Control
(TCDn.DLYCTRL) register and the Delay Value (TCDn.DLYVAL) register.
The inputs are connected to the Event System. The connections between the event source and the TCD input must
be configured in the Event System.
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Figure 22-9. TCD Input Overview
EVCTRLA.EDGE
Asynchonous overrride
EVCTRLA.ASYNC
Input Event A
INPUT
BLANKING
Input processing logic
(Input mode logic A)
Digital
Filter
EVCTRLA.FILTER
DLYPRESC
Change flow
INPUT
MODE
DLYTRIG
Synchronized
override
TC Core
(Timer/Counter,
compare values,
waveform generator)
DLYSEL
Output state
Output
control
INPUT
MODE
EVCTRLB.FILTER
Digital
Filter
Input Event B
EVCTRLB.EDGE
EVCTRLB.ASYNC
Change flow
Synchronized
override
Input processing logic
(Input mode logic B)
Asynchonous overrride
There is a delay of two/three clock cycles on the TCD synchronizer clock between receiving the input event,
processing it, and overriding the outputs. If using the asynchronous event detection, the outputs will override instantly
outside the input processing.
22.3.3.4.1 Input Blanking
Input blanking functionality masks out the input events for a programmable time in a selectable part of the TCD cycle.
Input blanking can be used to mask out ‘false’ input events triggered right after changes on the outputs occur.
Input blanking can be enabled by configuring the Delay Select (DLYSEL) bit field in the Delay Control
(TCDn.DLYCTRL) register. The trigger source is selected by the Delay Trigger (DLYTRIG) bit field in
TCDn.DLYCTRL.
Input blanking uses the delay clock. After a trigger, a counter counts up until the Delay Value (DLYVAL) bit field in the
Delay Value (TCDn.DLYVAL) register is reached. Afterward, input blanking is turned off. The TCD delay clock is a
prescaled version of the synchronizer clock (CLK_TCD_SYNC). The division factor is set by the Delay Prescaler
(DLYPRESC) bit field in the Delay Control (TCDn.DLYCTRL) register. The duration of the input blanking is given by:
�BLANK =
DLYPRESC_division_factor × DLYVAL
�CLK_TCD_SYNC
Input blanking uses the same logic as the programmable output event. For this reason, it is not possible to use both
at the same time.
22.3.3.4.2 Digital Filter
The digital filter for event input x is enabled by writing a ‘1’ to the FILTER bit in the corresponding Event Control
(TCDn.EVCTRLA or TCDn.EVCTRLB) register. When the digital filter is enabled, any pulse lasting less than four
counter clock cycles will be filtered out. Any change on the incoming event will, therefore, take four counter clock
cycles before it affects the input processing logic.
22.3.3.4.3 Asynchronous Event Detection
To enable asynchronous event detection on an input event, the Event Configuration (CFG) bit field in the
corresponding Event Control (TCDn.EVCTRLA or TCDn.EVCTRLB) register must be configured accordingly.
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TCD - 12-Bit Timer/Counter Type D
The asynchronous event detection makes it possible to asynchronously override the output when the input event
occurs. What the input event will do depends on the input mode. The outputs have direct override while the counter
flow will be changed when the event is synchronized to the synchronizer clock (CLK_TCD_SYNC).
It is not possible to use asynchronous event detection and digital filter at the same time.
22.3.3.4.4 Software Commands
The following table displays the commands for the TCD module.
Table 22-4. Software Commands
Trigger
Software Command
The SYNCEOC bit in the TCDn.CTRLE register
Update the double-buffered registers at the end of the
TCD cycle
The SYNC bit in the TCDn.CTRLE register
Update the double-buffered registers
The RESTART bit in the TCDn.CTRLE register
Restart the TCD counter
The SCAPTUREA bit in the TCDn.CTRLE register
Capture to Capture A (TCDn.CAPTUREAL/H) register
The SCAPTUREB bit in the TCDn.CTRLE register
Capture to Capture B (TCDn.CAPTUREBL/H) register
22.3.3.4.5 Input Modes
The user can select between ten input modes. The selection is done by writing to the Input Mode (INPUTMODE) bit
field in the Input Control (TCDn.INPUTCTRLA and TCDn.INPUTCTRLB) registers.
Input Modes Validity
Not all input modes work in all Waveform Generation modes. The table below shows the Waveform Generation
modes in which the different input modes are valid.
Table 22-5. Input Modes Validity
INPUTMODE
One Ramp Mode
Two Ramp Mode
Four Ramp Mode
Dual Slope Mode
0
Valid
Valid
Valid
Valid
1
Valid
Valid
Valid
Do not use
2
Do not use
Valid
Valid
Do not use
3
Do not use
Valid
Valid
Do not use
4
Valid
Valid
Valid
Valid
5
Do not use
Valid
Valid
Do not use
6
Do not use
Valid
Valid
Do not use
7
Valid
Valid
Valid
Valid
8
Valid
Valid
Valid
Do not use
9
Valid
Valid
Valid
Do not use
10
Valid
Valid
Valid
Do not use
Input Mode 0: Input Has No Action
In Input mode 0, the inputs do not affect the outputs, but they can still trigger captures and interrupts if enabled.
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Figure 22-10. Input Mode 0
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
DTB
WOA
WOB
INPUT A
INPUT B
Input Mode 1: Stop Output, Jump to Opposite Compare Cycle, and Wait
An input event in Input mode 1 will stop the output signal, jump to the opposite dead time, and wait until the input
event goes low before the TCD counter continues.
If Input mode 1 is used on input A, an event will only have an effect if the TCD is in dead time A or on time A, and it
will only affect the WOA output. When the event is done, the TCD counter starts at dead time B.
Figure 22-11. Input Mode 1 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
Wait
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
If Input mode 1 is used on input B, an event will only have an effect if the TCD is in dead time B or on time B, and it
will only affect the WOB output. When the event is done, the TCD counter starts at dead time A.
Figure 22-12. Input Mode 1 on Input B
DTA
OTA
DTB
OTB
Wait
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
Input Mode 2: Stop Output, Execute Opposite Compare Cycle, and Wait
An input event in Input mode 2 will stop the output signal, execute to the opposite dead time and on time, and then
wait until the input event goes low before the TCD counter continues. If the input is done before the opposite dead
time and on time have finished, there will be no waiting, but the opposite dead time and on time will continue.
If Input mode 2 is used on input A, an event will only have an effect if the TCD is in dead time A or on time A, and will
only affect the WOA output.
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Figure 22-13. Input Mode 2 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
Wait
DTA
OTA
WOA
WOB
INPUT A
INPUT B
If Input mode 2 is used on input B, an event will only have an effect if the TCD is in dead time B or on time B, and it
will only affect the WOB output.
Figure 22-14. Input Mode 2 on Input B
DTA
OTA
DTB
OTB
DTA
OTA
Wait
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
Input Mode 3: Stop Output, Execute Opposite Compare Cycle while Fault Active
An input event in Input mode 3 will stop the output signal and start executing the opposite dead time and on time
repetitively, as long as the Fault/input is active. When the input is released, the ongoing dead time and/or on time will
finish, and then the normal flow will start.
If Input mode 3 is used on input A, an event will only have an effect if the TCD is in dead time A or on time A.
Figure 22-15. Input Mode 3 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
If Input mode 3 is used on input B, an event will only have an effect if the TCD is in dead time B or on time B.
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Figure 22-16. Input Mode 3 on Input B
DTA
OTA
DTB
OTB
DTA
OTA
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
Input Mode 4: Stop all Outputs, Maintain Frequency
When Input mode 4 is used, both input A and input B will give the same functionality. An input event will deactivate
the outputs as long as the event is active. The TCD counter will not be affected by events in this input mode.
Figure 22-17. Input Mode 4
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
WOA
WOB
INPUT A/B
Input Mode 5: Stop all Outputs, Execute Dead Time while Fault Active
When Input mode 5 is used, both input A and input B give the same functionality. The input event stops the outputs
and starts on the opposite dead time if it occurs during an on time. If the event occurs during dead time, the dead
time will continue until the next on time is scheduled to start. Though, if the input is still active, the cycle will continue
with the other dead time. As long as the input event is active, alternating dead times will occur. When the input event
stops, the ongoing dead time will finish, and the next on time will continue in the normal flow.
Figure 22-18. Input Mode 5
DTA
OTA
DTB
OTB
DTA
OTA
DTB
DTA
DTB
DTA
DTB
OTB
WOA
WOB
INPUT A/B
Input Mode 6: Stop All Outputs, Jump to Next Compare Cycle, and Wait
When Input mode 6 is used, both input A and input B will give the same functionality. The input event stops the
outputs and jumps to the opposite dead time if it occurs during an on time. If the event occurs during dead time, the
dead time will continue until the next on time is scheduled to start. As long as the input event is active, the TCD
counter will wait. When the input event stops, the next dead time will start, and normal flow will continue.
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Figure 22-19. Input Mode 6
DTA
OTA
DTB
Wait
DTA
OTA
Wait
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A/B
Input Mode 7: Stop all Outputs, Wait for Software Action
When Input mode 7 is used, both input A and input B will give the same functionality. The input events stop the
outputs and the TCD counter. It will be stopped until a Restart command is given. If the input event is still high when
the Restart command (RESTART bit in TCDn.CTRLE register) is given, it will stop again. When the TCD counter
restarts, it will always start on dead time A.
Figure 22-20. Input Mode 7
DTA
OTA
DTB
OTB
DTA
OTA
Wait
DTA
OTA
WOA
WOB
INPUT A/B
Software Restart
command
Input Mode 8: Stop Output on Edge, Jump to Next Compare Cycle
In Input mode 8, a positive edge on the input event while the corresponding output is ON will cause the output to stop
and the TCD counter to jump to the opposite dead time.
If Input mode 8 is used on input A and a positive edge on the input event occurs while in on time A, the TCD counter
jumps to dead time B.
Figure 22-21. Input Mode 8 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
WOA
WOB
INPUT A
OR
INPUT A
If Input mode 8 is used on input B and a positive edge on the input event occurs while in on time B, the TCD counter
jumps to dead time A.
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Figure 22-22. Input Mode 8 on Input B
DTA
OTA
DTB
OTB DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
WOA
WOB
INPUT B
OR
INPUT B
Input Mode 9: Stop Output on Edge, Maintain Frequency
In Input mode 9, a positive edge on the input event while the corresponding output is ON will cause the output to stop
during the rest of the on time. The TCD counter will not be affected by the event, only the output.
If Input mode 9 is used on input A and a positive edge on the input event occurs while in on time A, the output will be
OFF for the rest of the on time.
Figure 22-23. Input Mode 9 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
If Input mode 9 is used on input B and a positive edge on the input event occurs while in on time B, the output will be
OFF for the rest of the on time.
Figure 22-24. Input Mode 9 on Input B
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
Input Mode 10: Stop Output at Level, Maintain Frequency
In Input mode 10, the input event will cause the corresponding output to stop, as long as the input is active. If the
input goes low while there must have been an on time on the corresponding output, the output will be deactivated for
the rest of the on time. The TCD counter is not affected by the event, only the output.
If Input mode 10 is used on input A and an input event occurs, the WOA will be OFF as long as the event lasts. If
released during an on time, it will be OFF for the rest of the on time.
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Figure 22-25. Input Mode 10 on Input A
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
If Input mode 10 is used on input B and an input event occurs, the WOB will be OFF as long as the event lasts. If
released during an on time, it will be OFF for the rest of the on time.
Figure 22-26. Input Mode 10 on Input B
DTA
OTA
DTB
OTB
DTA
OTA
DTB
OTB
DTA
OTA
WOA
WOB
INPUT A
INPUT B
Input Mode Summary
Table 22-6 summarizes the conditions, as illustrated in the timing diagrams of the preceding sections.
Table 22-6. Input Mode Summary
INPUTMODE
Trigger → Output Affected
Fault On/Active
Fault Release/Inactive
0
-
No action.
No action.
1
Input A→WOA
End the current on time and wait.
Start with dead time for
the other compare.
End the current on time, execute the
other compare cycle and wait.
Start with dead time for
the current compare.
Input B→WOB
Execute the current on time, then
execute the other compare cycle
repetitively.
Re-enable the current
compare cycle.
Input A→{WOA, WOB}
Deactivate the outputs.
Input B→WOB
2
Input A→WOA
Input B→WOB
3
4
Input A→WOA
Input B→{WOA, WOB}
5
Input A→{WOA, WOB}
Execute dead time only.
Input B→{WOA, WOB}
6
Input A→{WOA, WOB}
End on time and wait.
Input B→{WOA, WOB}
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...........continued
INPUTMODE
Trigger → Output Affected
Fault On/Active
Fault Release/Inactive
7
Input A→{WOA, WOB}
End on time and wait for software
action.
Start with dead time for
the current compare.
Input B→{WOA, WOB}
8
Input A→WOA
Input B→WOB
9
Input A→WOA
Input B→WOB
10
Input A→WOA
other
End the current on time and continue
with the other off time.
Block the current on time and
continue the sequence.
Input B→WOB
Deactivate on time until the end of
the sequence while the trigger is
active.
-
-
-
Note: When using different modes on each event input, take into consideration possible conflicts, keeping in mind
that TCD has a single counter, to avoid unexpected results.
22.3.3.5 Dithering
If it is not possible to achieve the desired frequency because of the prescaler/period selection limitations, dithering
can be used to approximate the desired frequency and reduce the waveform drift.
The dither accumulates the fractional error of the counter clock for each cycle. When the fractional error overflows, an
additional clock cycle is added to the selected part of the TCD cycle.
Example 22-1. Generate 75 kHz from a 10 MHz Clock
If the timer clock frequency is 10 MHz, it will give the timer a resolution of 100 ns. The desired
output frequency is 75 kHz, which means a period of 13333 ns. This period cannot be achieved
with a 100 ns resolution as it would require 133.33 cycles. The output period can be set to either
133 cycles (75.188 kHz) or 134 cycles (74.626 kHz).
It is possible to change the period between the two frequencies manually in the firmware to get an
average output frequency of 75 kHz (change every third period to 134 cycles). The dither can do
this automatically by accumulating the error (0.33 cycles). The accumulator calculates when the
accumulated error is larger than one clock cycle. When that happens, an additional cycle is added
to the timer period.
Figure 22-27. Dither Logic
Overflow
Dither value
ACCUMULATOR REGISTER
The user can select where in the TCD cycle the dither will be added by writing to the Dither Selection (DITHERSEL)
bits in the Dither Control (TCDn.DITCTRL) register:
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•
•
•
•
On time B
On time A and B
Dead time B
Dead time A and B
How much the dithering will affect the TCD cycle time depends on what Waveform Generation mode is used (see
Table 22-7). Dithering is not supported in Dual Slope mode.
Table 22-7. Mode-Dependent Dithering Additions to TCD Cycle
WAVEGEN
DITHERSEL in TCDn.DITCTRL
Additional TCD Clock Cycles to TCD Cycle
One Ramp mode
On time B
1
On time A and B
1
Dead time B
0
Dead time A and B
0
On time B
1
On time A and B
2
Dead time B
0
Dead time A and B
0
On time B
1
On time A and B
2
Dead time B
1
Dead time A and B
2
On time B
Not supported
On time A and B
Not supported
Dead time B
Not supported
Dead time A and B
Not supported
Two Ramp mode
Four Ramp mode
Dual Slope mode
The differences in the number of TCD clock cycles added to the TCD cycle are caused by the different number of
compare values used by the TCD cycle. For example, in One Ramp mode, only CMPBCLR affects the TCD cycle
time.
For DITHERSEL configurations where no extra cycles are added to the TCD cycles, compensation is reached by
shortening the following output state.
Example 22-2. DITHERSEL in One Ramp Mode
In One Ramp mode with DITHERSEL selecting dead time B, the dead time B will be increased by
one cycle when dither overflow occurs, reducing on time B by one cycle.
22.3.3.6 TCD Counter Capture
The TCD counter is asynchronous to the peripheral clock, so it is not possible to read out the counter value directly. It
is possible to capture the TCD counter value, synchronized to the I/O clock domain, in two ways:
• Capture value on input events
• Software capture
The capture logic contains two separate capture blocks, CAPTUREA and CAPTUREB, that can capture and
synchronize the TCD counter value to the I/O clock domain. CAPTUREA/B can be triggered by input event A/B or by
software.
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The capture values can be obtained by reading first TCDn.CAPTUREAL/TCDn.CAPTUREBL and then
TCDn.CAPTUREAH/TCDn.CAPTUREBH registers.
Captures Triggered by Input Events
To enable the capture on an input event, write a ‘1’ to the ACTION bit in the respective Event Control
(TCDn.EVCTRLA or TCDn.EVCTRLB) register when configuring an event input.
When a capture has occurred, the TRIGA/B flag is raised in the Interrupt Flags (TCDn.INTFLAGS) register. The
corresponding TRIGA/B interrupt can be enabled by writing a ‘1’ to the respective Trigger Interrupt Enable (TRIGA or
TRIGB) bit in the Interrupt Control (TCDn.INTCTRL) register. By polling TRIGA or TRIGB in TCDn.INTFLAGS, the
user knows that a CAPTURE value is available, and can read out the value by reading first the TCDn.CAPTUREAL
or TCDn.CAPTUREBL register and then the TCDn.CAPTUREAH or TCDn.CAPTUREBH register.
Example 22-3. PWM Capture
To perform a PWM capture, connect both event A and event B to the same asynchronous event
channel that contains the PWM signal. To get information on the PWM signal, configure one event
input to capture the rising edge of the signal. Configure the other event input to capture the falling
edge of the signal.
TCD cycle
Dead time A
On time A
Dead time B
On time B
Counter
value
Compare
values
EVENT
CMPBCLR
EVENT
CMPBSET
EVENT
* OVF
CMPACLR
EVENT
CMPASET
WOA
WOB
INPUT A
TRIGA*
INPUT B
TRIGA*
* TRIGB
TRIGA*
* TRIGB
* TRIGB
Note:
▲ Event trigger
* Interrupt trigger
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Capture Triggered by Software
The software can capture the TCD value by writing a ‘1’ to the respective Software Capture A/B Strobe
(SCAPTUREx) bit in the Control E (TCDn.CTRLE) register. When this command is executed and the Command
Ready (CMDRDY) bit in the Status (TCDn.STATUS) register reads ‘1’ again, the CAPTUREA/B value is available. It
can now be read by reading first the TCDn.CAPTUREAL or TCDn.CAPTUREBL register and then the
TCDn.CAPTUREAH or TCDn.CAPTUREBH register.
Using Capture Together with Input Modes
The capture functionality can be used together with input modes. The same event will then both capture the counter
value and trigger a change in the counter flow, depending on the input mode selected.
Example 22-4. Reset One Ramp Mode by Input Event Capture
In One Ramp mode, the counter can be reset by an input event capture. To achieve this, use input
event B and write 0x08 to the INPUTMODE bit field in the Input Control B (TCDn.INPUTCTRLB)
register.
DTA
OTA
DTB
DTA
OTA
Counter
value
CMPBCLR
CMPBSET
CMPACLR
CMPASET
INPUT B
22.3.3.7 Output Control
The outputs are configured by writing to the Fault Control (TCDn.FAULTCTRL) register. TCDn.FAULTCTRL is only
reset to ‘0’ after a POR reset. During the reset sequence after any Reset, TCDn.FAULTCTRL will get its values from
the TCD Fuse (FUSE.TCDCFG).
The Compare x Enable (CMPxEN) bits in TCDn.FAULTCTRL enable the different outputs. The CMPx bits in
TCDn.FAULTCTRL set the output values when a Fault is triggered.
The TCD itself generates two different outputs, WOA and WOB. The two additional outputs, WOC and WOD, can be
configured by software to be connected to either WOA or WOB by writing the Compare C/D Output Select
(CMPCSEL and CMPDSEL) bits in the Control C (TCDn.CTRLC) register.
The user can override the outputs based on the TCD counter state by writing a ‘1’ to the Compare Output Value
Override (CMPOVR) bit in the Control C (TCDn.CTRLC) register. The user can then select the output values in the
different dead and on times by writing to the Compare Value (CMPAVAL and CMPBVAL) bit fields in the Control D
(TCDn.CTRLD) register.
When used in One Ramp mode, WOA will only use the setup for dead time A (DTA) and on time A (OTA) to set the
output. WOB will only use dead time B (DTB) and on time B (OTB) values to set the output.
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When using the override feature together with Faults detection (input modes), the CMPA (and CMPC/D if WOC/D
equals WOA) bit in TCDn.FAULTCTRL must be equal to CMPAVAL[0] and [2] in CTRL. If not, the first cycle after a
Fault is detected can have the wrong polarity on the outputs. The same applies to CMPB in the TCDn.FAULTCTRL
(and CMPC/D if WOC/D equals WOB) bit, which must be equal to CMPBVAL[0] and [2] in TCDn.CTRLD.
Due to the asynchronous nature of the TCD and that input events can immediately affect the output signal, there is a
risk of nanosecond spikes occurring on the output without any load on the pin. The case occurs in any input mode
different from ‘0’ and when an input event is triggering. The spike value will always be in the direction of the CMPx
values given by the TCDn.FAULTCTRL register.
22.3.4
Events
The TCD can generate the events described in the following table:
Table 22-8. Event Generators in TCD
Generator Name
Peripheral
TCDn
Description
Event
CMPBCLR
The counter matches
CMPBCLR
CMPASET
The counter matches
CMPASET
Event
Type
Generating
Clock Domain
Pulse
CLK_TCD
Length of Event
One CLK_TCD_CNT period
CMPBSET The counter matches
CMPBSET
PROGEV
Programmable event output(1)
One CLK_TCD_SYNC period
Note:
1. The user can select the trigger and all the compare matches (including CMPACLR). Also, it is possible to delay
the output event from 0 to 255 TCD delay cycles.
The three events based on the counter match directly generate event strobes that last for one clock cycle on the TCD
counter clock. The programmable output event generates an event strobe that lasts for one clock cycle on the TCD
synchronizer clock.
The TCD can receive the events described in the following table:
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Table 22-9. Event Users and Available Event Actions in TCD
User Name
Peripheral
Description
Input
Input Detection Async/Sync
Stop the output, jump to the opposite compare cycle
and wait.
Stop the output, execute the opposite compare cycle
and wait.
Stop the output, execute the opposite compare cycle
while the Fault is active.
Stop all outputs, maintain the frequency.
TCDn
Level
Stop all outputs, execute dead time while the Fault is
Input A/ Input B active.
Both
Stop all outputs, jump to the next compare cycle and
wait.
Stop all outputs, wait for software action.
Stop the output on the edge, jump to the next
compare cycle.
Edge
Stop the output on the edge, maintain the frequency.
Stop the output at level, maintain the frequency.
Level
Input A and Input B are TCD event users that detect and act upon the input events. Additional information about input
events and how to configure them can be found in the 22.3.3.4 TCD Inputs section. Refer to the Event System
(EVSYS) section for more details regarding event types and Event System configuration.
22.3.4.1 Programmable Output Events
The Programmable Output Event (PROGEV) uses the same logic as the input blanking for trigger selection and
delay. Therefore, it is not possible to configure the functionalities independently. If the input blanking functionality is
used, the output event cannot be delayed, and the trigger used for input blanking will also be used for the output
event.
PROGEV is configured in the TCDn.DLYCTRL and TCDn.DLYVAL registers. It is possible to delay the output event
by 0 to 255 TCD delay clock cycles. The delayed output event functionality uses the TCD delay clock and counts until
the DLYVAL value is reached before the trigger is sent out as an event. The TCD delay clock is a prescaled version
of the TCD synchronizer clock (CLK_TCD_SYNC), and the division factor is set by the DLYPRESC bits in the
TCDn.DLYCTRL register. The output event will be delayed by the TCD clock period x DLYPRESC division factor x
DLYVAL.
22.3.5
Interrupts
Table 22-10. Available Interrupt Vectors and Sources
Name
Vector Description
Conditions
OVF
Overflow interrupt
The TCD finishes one TCD cycle.
TRIG
Trigger interrupt
•
•
TRIGA: On event input A
TRIGB: On event input B
When an interrupt condition occurs, the corresponding interrupt flag is set in the Interrupt Flags (TCDn.INTFLAGS)
register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the Interrupt Control
(TCDn.INTCTRL) register.
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An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
When several interrupt request conditions are supported by an interrupt vector, the interrupt requests are ORed
together into one combined interrupt request to the interrupt controller. The user must read the peripheral’s
INTFLAGS register to determine which of the interrupt conditions are present.
22.3.6
Sleep Mode Operation
The TCD operates in Idle sleep mode and is stopped when entering Standby and Power-Down sleep modes.
22.3.7
Debug Operation
Halting the CPU in Debugging mode will halt the normal operation of the peripheral. This peripheral can be forced to
operate with the CPU halted by writing a ‘1’ to the Debug Run (DBGRUN) bit in the Debug Control
(TCDn.DBGCTRL) register.
When the Fault Detection (FAULTDET) bit in TCDn.DBGCTRL is written to ‘1’, and the CPU is halted in Debug mode,
an event/Fault is created on both input event channels. These events/Faults last as long as the break and can serve
as a safeguard in Debug mode, for example, by forcing external components off.
If the peripheral is configured to require periodic service by the CPU through interrupts or similar, improper operation
or data loss may result during halted debugging.
22.3.8
Configuration Change Protection
This peripheral has registers that are under Configuration Change Protection (CCP). To write to these registers, a
certain key must first be written to the CPU.CCP register, followed by a write access to the protected bits within four
CPU instructions.
Attempting to write to a protected register without following the appropriate CCP unlock sequence leaves the
protected register unchanged.
The following registers are under CCP:
Table 22-11. Registers under Configuration Change Protection in TCD
Register
Key
TCDn.FAULTCTRL
IOREG
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TCD - 12-Bit Timer/Counter Type D
22.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
...
0x07
0x08
0x09
0x0A
...
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16
...
0x17
0x18
0x19
0x1A
...
0x1D
0x1E
0x1F
...
0x21
CTRLA
CTRLB
CTRLC
CTRLD
CTRLE
7:0
7:0
7:0
7:0
7:0
0x22
EVCTRLA
EVCTRLB
INTCTRL
INTFLAGS
STATUS
Reserved
INPUTCTRLA
INPUTCTRLB
FAULTCTRL
Reserved
DLYCTRL
DLYVAL
DITCTRL
DITVAL
CMPDSEL
3
CNTPRES[1:0]
CMPCSEL
CMPBVAL[3:0]
DISEOC
FIFTY
SCAPTUREB SCAPTUREA
2
1
0
SYNCPRES[1:0]
ENABLE
WGMODE[1:0]
AUPDATE
CMPOVR
CMPAVAL[3:0]
RESTART
SYNC
SYNCEOC
7:0
7:0
CFG[1:0]
CFG[1:0]
EDGE
EDGE
ACTION
ACTION
TRIGEI
TRIGEI
7:0
7:0
7:0
7:0
7:0
7:0
TRIGB
TRIGB
TRIGA
TRIGA
OVF
OVF
ENRDY
PWMACTB
CMPDEN
7:0
7:0
PWMACTA
CMPCEN
CMDRDY
CMPBEN
CMPAEN
CMPD
DLYPRESC[1:0]
INPUTMODE[3:0]
INPUTMODE[3:0]
CMPC
CMPB
DLYTRIG[1:0]
CMPA
DLYSEL[1:0]
DLYVAL[7:0]
7:0
7:0
DITHERSEL[1:0]
DITHER[3:0]
Reserved
DBGCTRL
7:0
FAULTDET
DBGRUN
Reserved
CAPTUREA
Reserved
0x28
CMPASET
22.5
CLKSEL[1:0]
4
Reserved
0x26
...
0x27
0x2E
5
Reserved
CAPTUREB
0x2C
6
Reserved
0x24
0x2A
7
CMPACLR
CMPBSET
CMPBCLR
7:0
15:8
7:0
15:8
CAPTUREA[7:0]
7:0
15:8
7:0
15:8
7:0
15:8
7:0
15:8
CMPASET[7:0]
CAPTUREA[11:8]
CAPTUREB[7:0]
CAPTUREB[11:8]
CMPASET[11:8]
CMPACLR[7:0]
CMPACLR[11:8]
CMPBSET[7:0]
CMPBSET[11:8]
CMPBCLR[7:0]
CMPBCLR[11:8]
Register Description
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22.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
CTRLA
0x00
0x00
Enable-protected
7
6
5
CLKSEL[1:0]
R/W
R/W
0
0
Access
Reset
4
3
CNTPRES[1:0]
R/W
R/W
0
0
2
1
SYNCPRES[1:0]
R/W
R/W
0
0
0
ENABLE
R/W
0
Bits 6:5 – CLKSEL[1:0] Clock Select
The Clock Select bits select the clock source of the TCD clock.
Value
Name
Description
0x0
0x1
0x2
0x3
20MHZ
EXTCLK
SYSCLK
Internal 16/20 MHz Oscillator (OSC20M)
Reserved
External Clock
System Clock
Bits 4:3 – CNTPRES[1:0] Counter Prescaler
The Counter Prescaler bits select the division factor of the TCD counter clock.
Value
Name
Description
0x0
DIV1
Division factor 1
0x1
DIV4
Division factor 4
0x2
DIV32
Division factor 32
0x3
Reserved
Bits 2:1 – SYNCPRES[1:0] Synchronization Prescaler
The Synchronization Prescaler bits select the division factor of the TCD clock.
Value
Name
Description
0x0
DIV1
Division factor 1
0x1
DIV2
Division factor 2
0x2
DIV4
Division factor 4
0x3
DIV8
Division factor 8
Bit 0 – ENABLE Enable
When writing to this bit, it will automatically be synchronized to the TCD clock domain.
This bit can be changed as long as the synchronization of this bit is not ongoing. See the Enable Ready (ENRDY) bit
in the Status (TCDn.STATUS) register.
This bit is not enable-protected.
Value
Name
Description
0
NO
The TCD is disabled.
1
YES
The TCD is enabled and running.
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22.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x01
0x00
-
6
5
4
3
Access
Reset
Bits 1:0 – WGMODE[1:0] Waveform Generation Mode
These bits select the waveform generation.
Value
Name
0x0
ONERAMP
0x1
TWORAMP
0x2
FOURRAMP
0x3
DS
© 2020 Microchip Technology Inc.
2
1
0
WGMODE[1:0]
R/W
R/W
0
0
Description
One Ramp mode
Two Ramp mode
Four Ramp mode
Dual Slope mode
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22.5.3
Control C
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CMPDSEL
R/W
0
CTRLC
0x02
0x00
-
6
CMPCSEL
R/W
0
5
4
3
FIFTY
R/W
0
2
1
AUPDATE
R/W
0
0
CMPOVR
R/W
0
Bit 7 – CMPDSEL Compare D Output Select
This bit selects which waveform will be connected to output D.
Value
Name
Description
0
PWMA
Waveform A
1
PWMB
Waveform B
Bit 6 – CMPCSEL Compare C Output Select
This bit selects which waveform will be connected to output C.
Value
Name
Description
0
PWMA
Waveform A
1
PWMB
Waveform B
Bit 3 – FIFTY Fifty Percent Waveform
If the two waveforms have identical characteristics, this bit can be written to ‘1’. This will cause any values written to
the TCDn.CMPBSET/TCDn.CLR register to also be written to the TCDn.CMPASET/TCDn.CLR register.
Bit 1 – AUPDATE Automatically Update
If this bit is written to ‘1’, synchronization at the end of the TCD cycle is automatically requested after the Compare B
Clear High (TCDn.CMPBCLRH) register is written.
If the fifty percent waveform is enabled by setting the FIFTY bit in this register, writing the Compare A Clear High
register will also request a synchronization at the end of the TCD cycle if the AUPDATE bit is set.
Bit 0 – CMPOVR Compare Output Value Override
When this bit is written to ‘1’, default values of the Waveform Outputs A and B are overridden by the values written in
the Compare x Value in Active state bit fields in the Control D register. See the 22.5.4 CTRLD register description for
more details.
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22.5.4
Control D
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
R/W
0
CTRLD
0x03
0x00
-
6
5
CMPBVAL[3:0]
R/W
R/W
0
0
4
3
R/W
0
R/W
0
2
1
CMPAVAL[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 0:3, 4:7 – CMPVAL Compare x Value (in Active state)
These bits set the logical value of the PWMx signal for the corresponding states in the TCD cycle.
These settings are valid only if the Compare Output Value Override (CMPOVR) bit in the Control C (TCDn.CTRLC)
register is written to ‘1’.
Table 22-12. Two and Four Ramp Mode
CMPxVAL
DTA
OTA
DTB
OTB
PWMA
PWMB
CMPAVAL[0]
CMPBVAL[0]
CMPAVAL[1]
CMPBVAL[1]
CMPAVAL[2]
CMPBVAL[2]
CMPAVAL[3]
CMPBVAL[3]
When used in One Ramp mode, WOA will only use the setup for dead time A (DTA) and on time A (OTA) to set the
output. WOB will only use dead time B (DTB) and on time B (OTB) values to set the output.
Table 22-13. One Ramp Mode
CMPxVAL
DTA
OTA
DTB
OTB
PWMA
PWMB
CMPAVAL[1]
-
CMPAVAL[0]
-
CMPBVAL[3]
CMPBVAL[2]
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TCD - 12-Bit Timer/Counter Type D
22.5.5
Control E
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
DISEOC
R/W
0
CTRLE
0x04
0x00
-
6
5
4
SCAPTUREB
R/W
0
3
SCAPTUREA
R/W
0
2
RESTART
R/W
0
1
SYNC
R/W
0
0
SYNCEOC
R/W
0
Bit 7 – DISEOC Disable at End of TCD Cycle Strobe
When this bit is written to ‘1’, the TCD will automatically disable at the end of the TCD cycle.
Note that ENRDY in TCDn.STATUS will stay low until the TCD is disabled.
Writing to this bit has effect only if there is no ongoing synchronization of the ENABLE value in TCDn.CTRLA with the
TCD domain. See also the ENRDY bit in TCDn.STATUS.
Bit 4 – SCAPTUREB Software Capture B Strobe
When this bit is written to ‘1’, a software capture to the Capture B (TCDn.CAPTUREBL/H) register is triggered as
soon as synchronization to the TCD clock domain occurs.
Writing to this bit has effect only if there is no ongoing synchronization of a command. See also the CMDRDY bit in
TCDn.STATUS.
Bit 3 – SCAPTUREA Software Capture A Strobe
When this bit is written to ‘1’, a software capture to the Capture A (TCDn.CAPTUREAL/H) register is triggered as
soon as synchronization to the TCD clock domain occurs.
Writing to this bit has effect only if there is no ongoing synchronization of a command. See also the CMDRDY bit in
TCDn.STATUS.
Bit 2 – RESTART Restart Strobe
When this bit is written to ‘1’, a restart of the TCD counter is executed as soon as this bit is synchronized to the TCD
domain.
Writing to this bit has effect only if there is no ongoing synchronization of a command. See also the CMDRDY bit in
TCDn.STATUS.
Bit 1 – SYNC Synchronize Strobe
When this bit is written to ‘1’, the double-buffered registers will be loaded to the TCD domain as soon as this bit is
synchronized to the TCD domain.
Writing to this bit has effect only if there is no ongoing synchronization of a command. See also the CMDRDY bit in
TCDn.STATUS.
Bit 0 – SYNCEOC Synchronize End of TCD Cycle Strobe
When this bit is written to ‘1’, the double-buffered registers will be loaded to the TCD domain at the end of the next
TCD cycle.
Writing to this bit has effect only if there is no ongoing synchronization of a command. See also the CMDRDY bit in
TCDn.STATUS.
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TCD - 12-Bit Timer/Counter Type D
22.5.6
Event Control A
Name:
Offset:
Reset:
Property:
Bit
EVCTRLA
0x08
0x00
-
7
6
CFG[1:0]
Access
Reset
R/W
0
R/W
0
5
4
EDGE
R/W
0
3
2
ACTION
R/W
0
1
0
TRIGEI
R/W
0
Bits 7:6 – CFG[1:0] Event Configuration
When the input capture noise canceler is activated (FILTERON), the event input is filtered. The filter function requires
four successive equal valued samples of the trigger pin to change its output. The input capture is, therefore, delayed
by four clock cycles when the noise canceler is enabled (FILTERON).
When the Asynchronous Event is enabled (ASYNCON), the event input will affect the output directly.
Value
Name
Description
0x0
NEITHER
Neither filter nor asynchronous event is enabled.
0x1
FILTERON
Input capture noise cancellation filter enabled.
0x2
ASYNCON
Asynchronous event output qualification enabled.
other
Reserved.
Bit 4 – EDGE Edge Selection
This bit is used to select the active edge or level for the event input.
Value
Name
Description
0
FALL_LOW The falling edge or low level of the event input triggers a Capture or Fault action.
1
RISE_HIGH The rising edge or high level of the event input triggers a Capture or Fault action.
Bit 2 – ACTION Event Action
This bit enables capturing on the event input. By default, the input will trigger a Fault, depending on the Input Control
register’s Input mode. It is also possible to trigger a capture on the event input.
Value
Name
Description
0
FAULT
Event triggers a Fault.
1
CAPTURE
Event triggers a Fault and capture.
Bit 0 – TRIGEI Trigger Event Input Enable
Writing this bit to ‘1’ enables event as the trigger for input A.
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TCD - 12-Bit Timer/Counter Type D
22.5.7
Event Control B
Name:
Offset:
Reset:
Property:
Bit
EVCTRLB
0x09
0x00
-
7
6
CFG[1:0]
Access
Reset
R/W
0
R/W
0
5
4
EDGE
R/W
0
3
2
ACTION
R/W
0
1
0
TRIGEI
R/W
0
Bits 7:6 – CFG[1:0] Event Configuration
When the input capture noise canceler is activated (FILTERON), the event input is filtered. The filter function requires
four successive equal valued samples of the trigger pin to change its output. The input capture is, therefore, delayed
by four clock cycles when the noise canceler is enabled (FILTERON).
When the Asynchronous Event is enabled (ASYNCON), the event input will affect the output directly.
Value
Name
Description
0x0
NEITHER
Neither filter nor asynchronous event is enabled.
0x1
FILTERON
Input capture noise cancellation filter enabled.
0x2
ASYNCON
Asynchronous event output qualification enabled.
other
Reserved.
Bit 4 – EDGE Edge Selection
This bit is used to select the active edge or level for the event input.
Value
Name
Description
0
FALL_LOW The falling edge or low level of the event input triggers a Capture or Fault action.
1
RISE_HIGH The rising edge or high level of the event input triggers a Capture or Fault action.
Bit 2 – ACTION Event Action
This bit enables capturing on the event input. By default, the input will trigger a Fault, depending on the Input Control
register’s Input mode. It is also possible to trigger a capture on the event input.
Value
Name
Description
0
FAULT
Event triggers a Fault.
1
CAPTURE
Event triggers a Fault and capture.
Bit 0 – TRIGEI Trigger Event Input Enable
Writing this bit to ‘1’ enables event as a trigger for input B.
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TCD - 12-Bit Timer/Counter Type D
22.5.8
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x0C
0x00
-
6
Access
Reset
5
4
3
TRIGB
R/W
0
2
TRIGA
R/W
0
1
0
OVF
R/W
0
Bit 3 – TRIGB Trigger B Interrupt Enable
Writing this bit to ‘1’ enables the interrupt when trigger input B is received.
Bit 2 – TRIGA Trigger A Interrupt Enable
Writing this bit to ‘1’ enables the interrupt when trigger input A is received.
Bit 0 – OVF Counter Overflow
Writing this bit to ‘1’ enables the restart-of-sequence interrupt or overflow interrupt.
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TCD - 12-Bit Timer/Counter Type D
22.5.9
Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x0D
0x00
-
6
Access
Reset
5
4
3
TRIGB
R/W
0
2
TRIGA
R/W
0
1
0
OVF
R/W
0
Bit 3 – TRIGB Trigger B Interrupt Flag
The Trigger B Interrupt (TRIGB) flag is set on a Trigger B or Capture B condition. The flag is cleared by writing a ‘1’ to
its bit location.
Bit 2 – TRIGA Trigger A Interrupt Flag
The Trigger A Interrupt (TRIGA) flag is set on a Trigger A or Capture A condition. The flag is cleared by writing a ‘1’ to
its bit location.
Bit 0 – OVF Overflow Interrupt Flag
The Overflow Flag (OVF) is set at the end of a TCD cycle. The flag is cleared by writing a ‘1’ to its bit location.
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TCD - 12-Bit Timer/Counter Type D
22.5.10 Status
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
PWMACTB
R/W
0
STATUS
0x0E
0x00
-
6
PWMACTA
R/W
0
5
4
3
2
1
CMDRDY
R
0
0
ENRDY
R
0
Bit 7 – PWMACTB PWM Activity on B
This bit is set by hardware each time the WOB output toggles from ‘0’ to ‘1’ or from ‘1’ to ‘0’.
This status bit must be cleared by software by writing a ‘1’ to it before new PWM activity can be detected.
Bit 6 – PWMACTA PWM Activity on A
This bit is set by hardware each time the WOA output toggles from ‘0’ to ‘1’ or from ‘1’ to ‘0’.
This status bit must be cleared by software by writing a ‘1’ to it before new PWM activity can be detected.
Bit 1 – CMDRDY Command Ready
This status bit tells when a command is synced to the TCD domain and the system is ready to receive new
commands.
The following actions clear the CMDRDY bit:
1. TCDn.CTRLE SYNCEOC strobe.
2. TCDn.CTRLE SYNC strobe.
3. TCDn.CTRLE RESTART strobe.
4. TCDn.CTRLE SCAPTUREA Capture A strobe.
5. TCDn.CTRLE SCAPTUREB Capture B strobe.
6. TCDn.CTRLC AUPDATE written to ‘1’ and writing to the TCDn.CMPBCLRH register.
Bit 0 – ENRDY Enable Ready
This status bit tells when the ENABLE value in TCDn.CTRLA is synced to the TCD domain and is ready to be written
to again.
The following actions clear the ENRDY bit:
1. Writing to the ENABLE bit in TCDn.CTRLA.
2. TCDn.CTRLE DISEOC strobe.
3. Going into BREAK in an On-Chip Debugging (OCD) session while the Debug Run (DBGCTRL) bit in
TCDn.DBGCTRL is ‘0’.
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TCD - 12-Bit Timer/Counter Type D
22.5.11 Input Control A
Name:
Offset:
Reset:
Property:
Bit
7
INPUTCTRLA
0x10
0x00
-
6
Access
Reset
5
4
3
R/W
0
2
1
INPUTMODE[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 3:0 – INPUTMODE[3:0] Input Mode
Value
Name
Description
0x0
NONE
The input has no action.
0x1
JMPWAIT
Stop the output, jump to the opposite compare cycle, and wait.
0x2
EXECWAIT
Stop the output, execute the opposite compare cycle, and wait.
0x3
EXECFAULT
Stop the output, execute the opposite compare cycle while the Fault is active.
0x4
FREQ
Stop all outputs, maintain the frequency.
0x5
EXECDT
Stop all outputs, execute dead time while the Fault is active.
0x6
WAIT
Stop all outputs, jump to the next compare cycle, and wait.
0x7
WAITSW
Stop all outputs, wait for software action.
0x8
EDGETRIG
Stop the output on the edge, jump to the next compare cycle.
0x9
EDGETRIGFREQ Stop the output on the edge, maintain the frequency.
0xA
LVLTRIGFREQ
Stop the output at level, maintain the frequency.
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TCD - 12-Bit Timer/Counter Type D
22.5.12 Input Control B
Name:
Offset:
Reset:
Property:
Bit
7
INPUTCTRLB
0x11
0x00
-
6
Access
Reset
5
4
3
R/W
0
2
1
INPUTMODE[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 3:0 – INPUTMODE[3:0] Input Mode
Value
Name
Description
0x0
NONE
The input has no action.
0x1
JMPWAIT
Stop the output, jump to the opposite compare cycle, and wait.
0x2
EXECWAIT
Stop the output, execute the opposite compare cycle, and wait.
0x3
EXECFAULT
Stop the output, execute the opposite compare cycle while the Fault is active.
0x4
FREQ
Stop all outputs, maintain the frequency.
0x5
EXECDT
Stop all outputs, execute dead time while the Fault is active.
0x6
WAIT
Stop all outputs, jump to the next compare cycle, and wait.
0x7
WAITSW
Stop all outputs, wait for software action.
0x8
EDGETRIG
Stop the output on the edge, jump to the next compare cycle.
0x9
EDGETRIGFREQ Stop the output on the edge, maintain the frequency.
0xA
LVLTRIGFREQ
Stop the output at level, maintain the frequency.
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TCD - 12-Bit Timer/Counter Type D
22.5.13 Fault Control
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CMPDEN
R/W
0
FAULTCTRL
0x12
0x00
Configuration Change Protection
6
CMPCEN
R/W
0
5
CMPBEN
R/W
0
4
CMPAEN
R/W
0
3
CMPD
R/W
0
2
CMPC
R/W
0
1
CMPB
R/W
0
0
CMPA
R/W
0
Bits 4, 5, 6, 7 – CMPEN Compare x Enable
This bit field enable compare as output on the pin. This bit field is reset to ‘0’ after a Power-On Reset. At any other
reset, the content is kept but during the reset sequence loaded from the TCD Configuration Fuse (FUSE.TCDCFG)
Bits 0, 1, 2, 3 – CMP Compare x Value
This bit field set the default state from Reset, or when an input event triggers a fault causing changes to the output.
This bit field is reset to ‘0’ after a Power-On Reset. At any other reset, the content is kept but during the reset
sequence loaded from the TCD Configuration Fuse (FUSE.TCDCFG).
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TCD - 12-Bit Timer/Counter Type D
22.5.14 Delay Control
Name:
Offset:
Reset:
Property:
Bit
7
DLYCTRL
0x14
0x00
-
6
Access
Reset
5
4
DLYPRESC[1:0]
R/W
R/W
0
0
3
2
DLYTRIG[1:0]
R/W
R/W
0
0
1
0
DLYSEL[1:0]
R/W
R/W
0
0
Bits 5:4 – DLYPRESC[1:0] Delay Prescaler
These bits control the prescaler settings for the blanking or output event delay.
Value
Name
Description
0x0
DIV1
Prescaler division factor 1
0x1
DIV2
Prescaler division factor 2
0x2
DIV4
Prescaler division factor 4
0x3
DIV8
Prescaler division factor 8
Bits 3:2 – DLYTRIG[1:0] Delay Trigger
These bits control the trigger of the blanking or output event delay.
Value
Name
Description
0x0
CMPASET
CMPASET triggers delay
0x1
CMPACLR
CMPACLR triggers delay
0x2
CMPBSET
CMPBSET triggers delay
0x3
CMPBCLR
CMPASET triggers delay (end of cycle)
Bits 1:0 – DLYSEL[1:0] Delay Select
These bits control what function must be used by the delay trigger, the blanking or output event delay.
Value
Name
Description
0x0
OFF
Delay functionality not used
0x1
INBLANK
Input blanking enabled
0x2
EVENT
Event delay enabled
0x3
Reserved
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TCD - 12-Bit Timer/Counter Type D
22.5.15 Delay Value
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
DLYVAL
0x15
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
3
DLYVAL[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DLYVAL[7:0] Delay Value
These bits configure the blanking/output event delay time or event output synchronization delay in a number of
prescaled TCD cycles.
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TCD - 12-Bit Timer/Counter Type D
22.5.16 Dither Control
Name:
Offset:
Reset:
Property:
Bit
7
DITCTRL
0x18
0x00
-
6
5
4
3
Access
Reset
2
1
0
DITHERSEL[1:0]
R/W
R/W
0
0
Bits 1:0 – DITHERSEL[1:0] Dither Select
This bit field selects which state of the TCD cycle will benefit from the dither function. See the 22.3.3.5 Dithering
section.
Value
Name
Description
0x0
ONTIMEB
On time ramp B
0x1
ONTIMEAB
On time ramp A and B
0x2
DEADTIMEB
Dead time ramp B
0x3
DEADTIMEAB
Dead time ramp A and B
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TCD - 12-Bit Timer/Counter Type D
22.5.17 Dither Value
Name:
Offset:
Reset:
Property:
Bit
7
DITVAL
0x19
0x00
-
6
Access
Reset
5
4
3
R/W
0
2
1
DITHER[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 3:0 – DITHER[3:0] Dither Value
These bits configure the fractional adjustment of the on time or off time, according to the Dither Selection
(DITHERSEL) bits in the Dither Control (TCDn.DITCTRL) register. The DITHER value is added to a 4-bit accumulator
at the end of each TCD cycle. When the accumulator overflows, the frequency adjustment will occur.
The DITHER bits are double-buffered, so the new value is copied when an update condition occurs.
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TCD - 12-Bit Timer/Counter Type D
22.5.18 Debug Control
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x1E
0x00
-
6
5
4
3
Access
Reset
2
FAULTDET
R/W
0
1
0
DBGRUN
R/W
0
Bit 2 – FAULTDET Fault Detection
This bit defines how the peripheral behaves when stopped in Debug mode.
Value
Name Description
0
NONE No Fault is generated if TCD is stopped in Debug mode.
1
FAULT A Fault is generated, and both trigger flags are set, if TCD is halted in Debug mode.
Bit 0 – DBGRUN Debug Run
When written to ‘1’, the peripheral will continue operating in Debug mode when the CPU is halted.
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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TCD - 12-Bit Timer/Counter Type D
22.5.19 Capture A
Name:
Offset:
Reset:
Property:
CAPTUREA
0x22
0x00
-
The TCDn.CAPTUREAL and TCDn.CAPTUREAH register pair represents the 12-bit TCDn.CAPTUREA value.
For capture operation, these registers constitute the second buffer level and access point for the CPU. The
TCDn.CAPTUREA registers are updated with the buffer value when an update condition occurs. The CAPTURE A
register contains the TCD counter value when a trigger A or software capture A occurs.
The TCD counter value is synchronized to CAPTUREA by either software or an event.
The capture register is blocked for an update of new capture data until the higher byte of this register is read.
Bit
15
14
13
Access
Reset
12
11
R
0
Bit
7
6
5
Access
Reset
R
0
R
0
R
0
4
3
CAPTUREA[7:0]
R
R
0
0
10
9
CAPTUREA[11:8]
R
R
0
0
8
R
0
2
1
0
R
0
R
0
R
0
Bits 11:0 – CAPTUREA[11:0] Capture A Byte
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TCD - 12-Bit Timer/Counter Type D
22.5.20 Capture B
Name:
Offset:
Reset:
Property:
CAPTUREB
0x24
0x00
-
The TCDn.CAPTUREBL and TCDn.CAPTUREBH register pair represents the 12-bit TCDn.CAPTUREB value.
For capture operation, these registers constitute the second buffer level and access point for the CPU. The
TCDn.CAPTUREB registers are updated with the buffer value when an update condition occurs. The CAPTURE B
register contains the TCD counter value when a trigger B or software capture B occurs.
The TCD counter value is synchronized to CAPTUREB by either software or an event.
The capture register is blocked for an update of new capture data until the higher byte of this register is read.
Bit
15
14
13
Access
Reset
12
11
R
0
Bit
7
6
5
Access
Reset
R
0
R
0
R
0
4
3
CAPTUREB[7:0]
R
R
0
0
10
9
CAPTUREB[11:8]
R
R
0
0
8
R
0
2
1
0
R
0
R
0
R
0
Bits 11:0 – CAPTUREB[11:0] Capture B Byte
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TCD - 12-Bit Timer/Counter Type D
22.5.21 Compare Set A
Name:
Offset:
Reset:
Property:
CMPASET
0x28
0x00
-
The TCDn.CMPASETL and TCDn.CMPASETH register pair represents the 12-bit TCDn.CMPASET value. This
register is continuously compared to the counter value. Then, the outputs from the comparators are used for
generating waveforms.
Bit
15
14
13
12
Access
Reset
Bit
Access
Reset
11
R/W
0
7
6
5
R/W
0
R/W
0
R/W
0
4
3
CMPASET[7:0]
R/W
R/W
0
0
10
9
CMPASET[11:8]
R/W
R/W
0
0
8
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 11:0 – CMPASET[11:0] Compare A Set
These bits hold the value of the compare register.
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TCD - 12-Bit Timer/Counter Type D
22.5.22 Compare Set B
Name:
Offset:
Reset:
Property:
CMPBSET
0x2C
0x00
-
The TCDn.CMPBSETL and TCDn.CMPBSETH register pair represents the 12-bit TCDn.CMPBSET value. This
register is continuously compared to the counter value. Then, the outputs from the comparators are used for
generating waveforms.
Bit
15
14
13
12
Access
Reset
Bit
Access
Reset
11
R/W
0
7
6
5
R/W
0
R/W
0
R/W
0
4
3
CMPBSET[7:0]
R/W
R/W
0
0
10
9
CMPBSET[11:8]
R/W
R/W
0
0
8
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 11:0 – CMPBSET[11:0] Compare B Set
These bits hold the value of the compare register.
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TCD - 12-Bit Timer/Counter Type D
22.5.23 Compare Clear A
Name:
Offset:
Reset:
Property:
CMPACLR
0x2A
0x00
-
The TCDn.CMPACLRL and TCDn.CMPACLRH register pair represents the 12-bit TCDn.CMPACLR value. This
register is continuously compared to the counter value. Then, the outputs from the comparators are used for
generating waveforms.
Bit
15
14
13
12
Access
Reset
Bit
Access
Reset
11
R/W
0
7
6
5
R/W
0
R/W
0
R/W
0
4
3
CMPACLR[7:0]
R/W
R/W
0
0
10
9
CMPACLR[11:8]
R/W
R/W
0
0
8
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 11:0 – CMPACLR[11:0] Compare A Clear
These bits hold the value of the compare register.
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TCD - 12-Bit Timer/Counter Type D
22.5.24 Compare Clear B
Name:
Offset:
Reset:
Property:
CMPBCLR
0x2E
0x00
-
The TCDn.CMPBCLRL and TCDn.CMPBCLRH register pair represents the 12-bit TCDn.CMPBCLR value. This
register is continuously compared to the counter value. Then, the outputs from the comparators are used for
generating waveforms.
Bit
15
14
13
12
Access
Reset
Bit
Access
Reset
11
R/W
0
7
6
5
R/W
0
R/W
0
R/W
0
4
3
CMPBCLR[7:0]
R/W
R/W
0
0
10
9
CMPBCLR[11:8]
R/W
R/W
0
0
8
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 11:0 – CMPBCLR[11:0] Compare B Clear
These bits hold the value of the compare register.
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RTC - Real-Time Counter
23.
RTC - Real-Time Counter
23.1
Features
•
•
•
•
•
•
•
•
23.2
16-bit Resolution
Selectable Clock Sources
Programmable 15-bit Clock Prescaling
One Compare Register
One Period Register
Clear Timer on Period Overflow
Optional Interrupt/Event on Overflow and Compare Match
Periodic Interrupt and Event
Overview
The RTC peripheral offers two timing functions: the Real-Time Counter (RTC) and a Periodic Interrupt Timer (PIT).
The PIT functionality can be enabled independently of the RTC functionality.
RTC - Real-Time Counter
The RTC counts (prescaled) clock cycles in a Counter register and compares the content of the Counter register to a
Period register and a Compare register.
The RTC can generate both interrupts and events on compare match or overflow. It will generate a compare interrupt
and/or event at the first count after the counter equals the Compare register value, and an overflow interrupt and/or
event at the first count after the counter value equals the Period register value. The overflow will reset the counter
value to zero.
The RTC peripheral typically runs continuously, including in Low-Power Sleep modes, to keep track of time. It can
wake up the device from sleep modes and/or interrupt the device at regular intervals.
The reference clock is typically the 32.768 kHz output from an external crystal. The RTC can also be clocked from an
external clock signal, the 32.768 kHz Internal Ultra Low-Power Oscillator (OSCULP32K), or the OSCULP32K divided
by 32.
The RTC peripheral includes a 15-bit programmable prescaler that can scale down the reference clock before it
reaches the counter. A wide range of resolutions and time-out periods can be configured for the RTC. With a 32.768
kHz clock source, the maximum resolution is 30.5 μs, and time-out periods can be up to two seconds. With a
resolution of 1s, the maximum time-out period is more than 18 hours (65536 seconds).
PIT - Periodic Interrupt Timer
The PIT uses the same clock source (CLK_RTC) as the RTC function and can generate an interrupt request or a
level event on every nth clock period. The n can be selected from {4, 8, 16,... 32768} for interrupts and from {64, 128,
256,... 8192} for events.
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23.2.1
Block Diagram
Figure 23-1. RTC Block Diagram
EXTCLK
TOSC1
TOSC2
External Clock
32.768 kHz Crystal Osc.
32.768 kHz Int. Osc.
DIV32
PER
CLK_RTC
Correction
counter
RTC
15-bit
prescaler
PIT
=
Overflow
=
Compare
CNT
CMP
Period
23.3
Clocks
The peripheral clock (CLK_PER) is required to be at least four times faster than the RTC clock (CLK_RTC) for
reading the counter value, regardless of the prescaler setting.
A 32.768 kHz crystal can be connected to the TOSC1 or TOSC2 pins, along with any required load capacitors.
Alternatively, an external digital clock can be connected to the TOSC1 pin.
23.4
RTC Functional Description
The RTC peripheral offers two timing functions: the Real-Time Counter (RTC) and a Periodic Interrupt Timer (PIT).
This subsection describes the RTC.
23.4.1
Initialization
Before enabling the RTC peripheral and the desired actions (interrupt requests and output events), the source clock
for the RTC counter must be configured to operate the RTC.
23.4.1.1 Configure the Clock CLK_RTC
To configure the CLK_RTC, follow these steps:
1.
2.
Configure the desired oscillator to operate as required, in the Clock Controller (CLKCTRL) peripheral.
Write the Clock Select (CLKSEL) bit field in the Clock Selection (RTC.CLKSEL) register accordingly.
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The CLK_RTC clock configuration is used by both RTC and PIT functionality.
23.4.1.2 Configure RTC
To operate the RTC, follow these steps:
1.
2.
3.
4.
Set the compare value in the Compare (RTC.CMP) register, and/or the overflow value in the Period
(RTC.PER) register.
Enable the desired interrupts by writing to the respective interrupt enable bits (CMP, OVF) in the Interrupt
Control (RTC.INTCTRL) register.
Configure the RTC internal prescaler by writing the desired value to the Prescaler (PRESCALER) bit field in
the Control A (RTC.CTRLA) register.
Enable the RTC by writing a ‘1’ to the RTC Peripheral Enable (RTCEN) bit in the RTC.CTRLA register.
Note: The RTC peripheral is used internally during device start-up. Always check the Synchronization Busy bits in
the Status (RTC.STATUS) and Periodic Interrupt Timer Status (RTC.PITSTATUS) registers, and on the initial
configuration.
23.4.2
Operation - RTC
23.4.2.1 Enabling and Disabling
The RTC is enabled by writing the RTC Peripheral Enable (RTCEN) bit in the Control A (RTC.CTRLA) register to ‘1’.
The RTC is disabled by writing the RTC Peripheral Enable (RTCEN) bit in RTC.CTRLA to ‘0’.
23.5
PIT Functional Description
The RTC peripheral offers two timing functions: the Real-Time Counter (RTC) and a Periodic Interrupt Timer (PIT).
This subsection describes the PIT.
23.5.1
Initialization
To operate the PIT, follow these steps:
1. Configure the RTC clock CLK_RTC as described in section 23.4.1.1 Configure the Clock CLK_RTC.
2. Enable the interrupt by writing a ‘1’ to the Periodic Interrupt (PI) bit in the PIT Interrupt Control
(RTC.PITINTCTRL) register.
3. Select the period for the interrupt by writing the desired value to the Period (PERIOD) bit field in the Periodic
Interrupt Timer Control A (RTC.PITCTRLA) register.
4. Enable the PIT by writing a ‘1’ to the Periodic Interrupt Timer Enable (PITEN) bit in the RTC.PITCTRLA
register.
Note: The RTC peripheral is used internally during device start-up. Always check the Synchronization Busy bits in
the RTC.STATUS and RTC.PITSTATUS registers, and on the initial configuration.
23.5.2
Operation - PIT
23.5.2.1 Enabling and Disabling
The PIT is enabled by writing the Periodic Interrupt Timer Enable (PITEN) bit in the Periodic Interrupt Timer Control A
(RTC.PITCTRLA) register to ‘1’. The PIT is disabled by writing the Periodic Interrupt Timer Enable (PITEN) bit in
RTC.PITCTRLA to ‘0’.
23.5.2.2 PIT Interrupt Timing
Timing of the First Interrupt
The PIT function and the RTC function are running from the same counter inside the prescaler and can be configured
as described below:
• The RTC interrupt period is configured by writing the Period (RTC.PER) register
• The PIT interrupt period is configured by writing the Period (PERIOD) bit field in Periodic Interrupt Timer Control
A (RTC.PITCTRLA) register
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The prescaler is OFF when both functions are OFF (RTC Peripheral Enable (RTCEN) bit in RTC.CTRLA and the
Periodic Interrupt Timer Enable (PITEN) bit in RTC.PITCTRLA are ‘0’), but it is running (that is, its internal counter is
counting) when either function is enabled. For this reason, the timing of the first PIT interrupt and the first RTC count
tick will be unknown (anytime between enabling and a full period).
Continuous Operation
After the first interrupt, the PIT will continue toggling every ½ PIT period resulting in a full PIT period signal.
Example 23-1. PIT Timing Diagram for PERIOD=CYC16
For PERIOD=CYC16 in RTC.PITCTRLA, the PIT output effectively follows the state of the
prescaler counter bit 3, so the resulting interrupt output has a period of 16 CLK_RTC cycles.
The time between writing PITEN to ‘1’ and the first PIT interrupt can vary between virtually zero
and a full PIT period of 16 CLK_RTC cycles. The precise delay between enabling the PIT and its
first output depends on the prescaler’s counting phase: the first interrupt shown below is produced
by writing PITEN to ‘1’ at any time inside the leading time window.
Figure 23-2. Timing Between PIT Enable and First Interrupt
Prescaler
counter
value (LSB)
..000000
..000001
..000010
..000011
..000100
..000101
..000110
..000111
..001000
..001001
..001010
..001011
..001100
..001101
..001110
..001111
..010000
..010001
..010010
..010011
..010100
..010101
..010110
..010111
..011000
..011001
..011010
..011011
..011100
..011101
..011110
..011111
..100000
..100001
..100010
..100011
..100100
..100101
..100110
..100111
..101000
..101001
..101010
..101011
..101100
..101101
..101110
..101111
CLK_RTC
Prescaler bit 3
(CYC16)
Continuous Operation
PITENABLE=0
PIT output
Time window for writing
PITENABLE=1
First PIT output
23.6
Events
The RTC can generate the events described in the following table:
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RTC - Real-Time Counter
Table 23-1. RTC Event Generators
Generator Name
Description
Event
Type
Generating
Clock Domain
Length of the Event
OVF
Overflow
Pulse
CLK_RTC
One CLK_RTC period
CMP
Compare Match
Module Event
RTC
One CLK_RTC period
PIT_DIV8192 Prescaled RTC clock
divided by 8192
Level
Given by prescaled RTC clock
divided by 8192
PIT_DIV4096 Prescaled RTC clock
divided by 4096
Given by prescaled RTC clock
divided by 4096
PIT_DIV2048 Prescaled RTC clock
divided by 2048
Given by prescaled RTC clock
divided by 2048
PIT_DIV1024 Prescaled RTC clock
divided by 1024
Given by prescaled RTC clock
divided by 1024
PIT_DIV512
Prescaled RTC clock
divided by 512
Given by prescaled RTC clock
divided by 512
PIT_DIV256
Prescaled RTC clock
divided by 256
Given by prescaled RTC clock
divided by 256
PIT_DIV128
Prescaled RTC clock
divided by 128
Given by prescaled RTC clock
divided by 128
PIT_DIV64
Prescaled RTC clock
divided by 64
Given by prescaled RTC clock
divided by 64
The conditions for generating the OVF and CMP events are identical to those that will raise the corresponding
interrupt flags in the RTC.INTFLAGS register.
Refer to the (EVSYS) Event System section for more details regarding event users and Event System configuration.
23.7
Interrupts
Table 23-2. Available Interrupt Vectors and Sources
Name Vector Description
RTC
Real-Time Counter overflow
and compare match interrupt
Conditions
•
•
PIT
Periodic Interrupt Timer
interrupt
Overflow (OVF): The counter has reached the value from the
RTC.PER register and wrapped to zero.
Compare (CMP): Match between the value from the Counter
(RTC.CNT) register and the value from the Compare (RTC.CMP)
register.
A time period has passed, as configured by the PERIOD bit field in
RTC.PITCTRLA.
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
Note that:
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•
•
23.8
The RTC has two INTFLAGS registers: RTC.INTFLAGS and RTC.PITINTFLAGS.
The RTC has two INTCTRL registers: RTC.INTCTRL and RTC.PITINTCTRL.
Sleep Mode Operation
The RTC will continue to operate in Idle Sleep mode. It will run in Standby Sleep mode if the Run in Standby
(RUNSTDBY) bit in RTC.CTRLA is set.
The PIT will continue to operate in any sleep mode.
23.9
Synchronization
Both the RTC and the PIT are asynchronous, operating from a different clock source (CLK_RTC) independently of
the peripheral clock (CLK_PER). For Control and Count register updates, it will take some RTC and/or peripheral
clock cycles before an updated register value is available in a register or until a configuration change affects the RTC
or PIT, respectively. This synchronization time is described for each register in the Register Description section.
For some RTC registers, a Synchronization Busy flag is available (CMPBUSY, PERBUSY, CNTBUSY, CTRLABUSY)
in the Status (RTC.STATUS) register.
For the RTC.PITCTRLA register, a Synchronization Busy flag is available (CTRLBUSY) in the Periodic Interrupt
Timer Status (RTC.PITSTATUS) register.
Check these flags before writing to the mentioned registers.
23.10
Debug Operation
If the Debug Run (DBGRUN) bit in the Debug Control (RTC.DBGCTRL) register is ‘1’, the RTC will continue normal
operation. If DBGRUN is ‘0’ and the CPU is halted, the RTC will halt the operation and ignore any incoming events.
If the Debug Run (DBGRUN) bit in the Periodic Interrupt Timer Debug Control (RTC.PITDBGCTRL) register is ‘1’, the
PIT will continue normal operation. If DBGRUN is ‘0’ in the Debug mode and the CPU is halted, the PIT output will be
low. When the PIT output is high at the time, a new positive edge occurs to set the interrupt flag when restarting from
a break. The result is an additional PIT interrupt that would not happen during normal operation. If the PIT output is
low at the break, the PIT will resume low without additional interrupt.
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23.11
Register Summary
Offset
Name
Bit Pos.
7
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
CTRLA
STATUS
INTCTRL
INTFLAGS
TEMP
DBGCTRL
Reserved
CLKSEL
7:0
7:0
7:0
7:0
7:0
7:0
RUNSTDBY
0x08
CNT
0x0A
PER
0x0C
CMP
0x0E
...
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
23.12
6
5
4
3
2
1
0
CMPBUSY
PERBUSY
CNTBUSY
CMP
CMP
RTCEN
CTRLABUSY
OVF
OVF
PRESCALER[3:0]
TEMP[7:0]
DBGRUN
7:0
7:0
15:8
7:0
15:8
7:0
15:8
CLKSEL[1:0]
CNT[7:0]
CNT[15:8]
PER[7:0]
PER[15:8]
CMP[7:0]
CMP[15:8]
Reserved
PITCTRLA
PITSTATUS
PITINTCTRL
PITINTFLAGS
Reserved
PITDBGCTRL
7:0
7:0
7:0
7:0
PERIOD[3:0]
7:0
PITEN
CTRLBUSY
PI
PI
DBGRUN
Register Description
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23.12.1 Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RUNSTDBY
R/W
0
CTRLA
0x00
0x00
-
6
R/W
0
5
4
PRESCALER[3:0]
R/W
R/W
0
0
3
R/W
0
2
1
0
RTCEN
R/W
0
Bit 7 – RUNSTDBY Run in Standby
Value
Description
0
RTC disabled in Standby Sleep mode
1
RTC enabled in Standby Sleep mode
Bits 6:3 – PRESCALER[3:0] Prescaler
These bits define the prescaling of the CLK_RTC clock signal. Due to synchronization between the RTC clock and
the peripheral clock, there is a latency of two RTC clock cycles from updating the register until this has an effect.
Application software needs to check that the CTRLABUSY flag in RTC.STATUS register is cleared before writing to
this register.
Value
Name
Description
0x0
DIV1
RTC clock/1 (no prescaling)
0x1
DIV2
RTC clock/2
0x2
DIV4
RTC clock/4
0x3
DIV8
RTC clock/8
0x4
DIV16
RTC clock/16
0x5
DIV32
RTC clock/32
0x6
DIV64
RTC clock/64
0x7
DIV128
RTC clock/128
0x8
DIV256
RTC clock/256
0x9
DIV512
RTC clock/512
0xA
DIV1024
RTC clock/1024
0xB
DIV2048
RTC clock/2048
0xC
DIV4096
RTC clock/4096
0xD
DIV8192
RTC clock/8192
0xE
DIV16384
RTC clock/16384
0xF
DIV32768
RTC clock/32768
Bit 0 – RTCEN RTC Peripheral Enable
Value
Description
0
RTC peripheral is disabled
1
RTC peripheral is enabled
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23.12.2 Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x01
0x00
-
6
Access
Reset
5
4
3
CMPBUSY
R
0
2
PERBUSY
R
0
1
CNTBUSY
R
0
0
CTRLABUSY
R
0
Bit 3 – CMPBUSY Compare Synchronization Busy
This bit is ‘1’ when the RTC is busy synchronizing the Compare (RTC.CMP) register in the RTC clock domain.
Bit 2 – PERBUSY Period Synchronization Busy
This bit is ‘1’ when the RTC is busy synchronizing the Period (RTC.PER) register in the RTC clock domain.
Bit 1 – CNTBUSY Counter Synchronization Busy
This bit is ‘1’ when the RTC is busy synchronizing the Count (RTC.CNT) register in the RTC clock domain.
Bit 0 – CTRLABUSY Control A Synchronization Busy
This bit is ‘1’ when the RTC is busy synchronizing the Control A (RTC.CTRLA) register in the RTC clock domain.
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23.12.3 Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x02
0x00
-
6
5
4
3
Access
Reset
2
1
CMP
R/W
0
0
OVF
R/W
0
Bit 1 – CMP Compare Match Interrupt Enable
Enable interrupt-on-compare match (that is, when the value from the Count (RTC.CNT) register matches the value
from the Compare (RTC.CMP) register).
Value
Description
0
The compare match interrupt is disabled
1
The compare match interrupt is enabled
Bit 0 – OVF Overflow Interrupt Enable
Enable interrupt-on-counter overflow (that is, when the value from the Count (RTC.CNT) register matched the value
from the Period (RTC.PER) register and wraps around to zero).
Value
Description
0
The overflow interrupt is disabled
1
The overflow interrupt is enabled
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23.12.4 Interrupt Flag
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x03
0x00
-
6
5
4
3
Access
Reset
2
1
CMP
R/W
0
0
OVF
R/W
0
Bit 1 – CMP Compare Match Interrupt Flag
This flag is set when the value from the Count (RTC.CNT) register matches the value from the Compare (RTC.CMP)
register.
Writing a ‘1’ to this bit clears the flag.
Bit 0 – OVF Overflow Interrupt Flag
This flag is set when the value from the Count (RTC.CNT) register has reached the value from the Period (RTC.PER)
register and wrapped to zero.
Writing a ‘1’ to this bit clears the flag.
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23.12.5 Temporary
Name:
Offset:
Reset:
Property:
TEMP
0x4
0x00
-
The Temporary register is used by the CPU for 16-bit single-cycle access to the 16-bit registers of this peripheral. The
register is common for all the 16-bit registers of this peripheral and can be read and written by software. For more
details on reading and writing 16-bit registers, refer to Accessing 16-Bit Registers in the AVR CPU section.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
TEMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TEMP[7:0] Temporary
Temporary register for read/write operations in 16-bit registers.
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23.12.6 Debug Control
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x05
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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23.12.7 Clock Selection
Name:
Offset:
Reset:
Property:
Bit
CLKSEL
0x07
0x00
-
7
6
5
4
3
Access
Reset
2
1
0
CLKSEL[1:0]
R/W
R/W
0
0
Bits 1:0 – CLKSEL[1:0] Clock Select
Writing these bits select the source for the RTC clock (CLK_RTC).
Value
Name
Description
0x0
0x1
0x2
0x3
INT32K
INT1K
TOSC32K
EXTCLK
32.768 kHz from OSCULP32K
1.024 kHz from OSCULP32K
32.768 kHz from XOSC32K or external clock from TOSC1
External clock from EXTCLK pin
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23.12.8 Count
Name:
Offset:
Reset:
Property:
CNT
0x08
0x0000
-
The RTC.CNTL and RTC.CNTH register pair represents the 16-bit value, RTC.CNT. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Due to the synchronization between the RTC clock and main clock domains, there is a latency of two RTC clock
cycles from updating the register until this has an effect. The application software needs to check that the CNTBUSY
flag in RTC.STATUS is cleared before writing to this register.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CNT[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
CNT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CNT[15:8] Counter High Byte
These bits hold the MSB of the 16-bit Counter register.
Bits 7:0 – CNT[7:0] Counter Low Byte
These bits hold the LSB of the 16-bit Counter register.
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23.12.9 Period
Name:
Offset:
Reset:
Property:
PER
0x0A
0xFFFF
-
The RTC.PERL and RTC.PERH register pair represents the 16-bit value, RTC.PER. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Due to the synchronization between the RTC clock and main clock domains, there is a latency of two RTC clock
cycles from updating the register until this has an effect. The application software needs to check that the PERBUSY
flag in RTC.STATUS is cleared before writing to this register.
Bit
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
PER[15:8]
Access
Reset
Bit
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
PER[7:0]
Access
Reset
R/W
1
R/W
1
R/W
1
R/W
1
Bits 15:8 – PER[15:8] Period High Byte
These bits hold the MSB of the 16-bit Period register.
Bits 7:0 – PER[7:0] Period Low Byte
These bits hold the LSB of the 16-bit Period register.
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23.12.10 Compare
Name:
Offset:
Reset:
Property:
CMP
0x0C
0x0000
-
The RTC.CMPL and RTC.CMPH register pair represents the 16-bit value, RTC.CMP. The low byte [7:0] (suffix L) is
accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
CMP[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
CMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – CMP[15:8] Compare High Byte
These bits hold the MSB of the 16-bit Compare register.
Bits 7:0 – CMP[7:0] Compare Low Byte
These bits hold the LSB of the 16-bit Compare register.
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23.12.11 Periodic Interrupt Timer Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
PITCTRLA
0x10
0x00
-
6
R/W
0
5
4
PERIOD[3:0]
R/W
R/W
0
0
3
2
R/W
0
1
0
PITEN
R/W
0
Bits 6:3 – PERIOD[3:0] Period
Writing this bit field selects the number of RTC clock cycles between each interrupt.
Value
Name
Description
0x0
OFF
No interrupt
0x1
CYC4
4 cycles
0x2
CYC8
8 cycles
0x3
CYC16
16 cycles
0x4
CYC32
32 cycles
0x5
CYC64
64 cycles
0x6
CYC128
128 cycles
0x7
CYC256
256 cycles
0x8
CYC512
512 cycles
0x9
CYC1024
1024 cycles
0xA
CYC2048
2048 cycles
0xB
CYC4096
4096 cycles
0xC
CYC8192
8192 cycles
0xD
CYC16384
16384 cycles
0xE
CYC32768
32768 cycles
0xF
Reserved
Bit 0 – PITEN Periodic Interrupt Timer Enable
Value
Description
0
Periodic Interrupt Timer disabled
1
Periodic Interrupt Timer enabled
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23.12.12 Periodic Interrupt Timer Status
Name:
Offset:
Reset:
Property:
Bit
7
PITSTATUS
0x11
0x00
-
6
5
4
3
Access
Reset
2
1
0
CTRLBUSY
R
0
Bit 0 – CTRLBUSY PITCTRLA Synchronization Busy
This bit is ‘1’ when the RTC is busy synchronizing the Periodic Interrupt Timer Control A (RTC.PITCTRLA) register in
the RTC clock domain.
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23.12.13 PIT Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
PITINTCTRL
0x12
0x00
-
6
5
4
3
Access
Reset
2
1
0
PI
R/W
0
Bit 0 – PI Periodic Interrupt
Value
Description
0
The periodic interrupt is disabled
1
The periodic interrupt is enabled
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23.12.14 PIT Interrupt Flag
Name:
Offset:
Reset:
Property:
Bit
7
PITINTFLAGS
0x13
0x00
-
6
5
4
3
Access
Reset
2
1
0
PI
R/W
0
Bit 0 – PI Periodic Interrupt Flag
This flag is set when a periodic interrupt is issued.
Writing a ‘1’ clears the flag.
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23.12.15 Periodic Interrupt Timer Debug Control
Name:
Offset:
Reset:
Property:
Bit
7
PITDBGCTRL
0x15
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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24.
USART - Universal Synchronous and Asynchronous Receiver and
Transmitter
24.1
Features
•
•
•
•
•
•
•
•
•
•
•
•
24.2
Full-Duplex Operation
Half-Duplex Operation:
– One-Wire mode
– RS-485 mode
Asynchronous or Synchronous Operation
Supports Serial Frames with Five, Six, Seven, Eight or Nine Data Bits and One or Two Stop Bits
Fractional Baud Rate Generator:
– Can generate the desired baud rate from any peripheral clock frequency
– No need for an external oscillator
Built-In Error Detection and Correction Schemes:
– Odd or even parity generation and parity check
– Buffer overflow and frame error detection
– Noise filtering including false Start bit detection and digital low-pass filter
Separate Interrupts for:
– Transmit complete
– Transmit Data register empty
– Receive complete
Host SPI Mode
Multiprocessor Communication Mode
Start-of-Frame Detection
IRCOM Module for IrDA® Compliant Pulse Modulation/Demodulation
LIN Client Support
Overview
The Universal Synchronous and Asynchronous serial Receiver and Transmitter (USART) is a fast and flexible serial
communication peripheral. The USART supports several different modes of operation that can accommodate multiple
types of applications and communication devices. For example, the One-Wire Half-Duplex mode is useful when low
pin count applications are desired. The communication is frame-based, and the frame format can be customized to
support a wide range of standards.
The USART is buffered in both directions, enabling continued data transmission without any delay between frames.
Separate interrupts for receive and transmit completion allow fully interrupt-driven communication.
The transmitter consists of a two-level write buffer, a Shift register, and control logic for different frame formats. The
receiver consists of a two-level receive buffer and a Shift register. The status information of the received data is
available for error checking. Data and clock recovery units ensure robust synchronization and noise filtering during
asynchronous data reception.
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24.2.1
Block Diagram
Figure 24-1. USART Block Diagram
CLOCK GENERATOR
BAUD
Baud Rate Generator
XCK
TRANSMITTER
XDIR
TX Shift Register
TX Buffer
TXD
TXDATA
RECEIVER
RX Shift Register
RX Buffer
RXD
RXDATA
24.2.2
Signal Description
Signal
Type
Description
XCK
Output/input
Clock for synchronous operation
XDIR
Output
Transmit enable for RS-485
TxD
Output/input
Transmitting line (and receiving line in One-Wire mode)
RxD
Input
Receiving line
24.3
Functional Description
24.3.1
Initialization
Full-Duplex Mode:
1.
2.
3.
4.
Set the baud rate (USARTn.BAUD).
Set the frame format and mode of operation (USARTn.CTRLC).
Configure the TXD pin as an output.
Enable the transmitter and the receiver (USARTn.CTRLB).
Notes:
• For interrupt-driven USART operation, global interrupts must be disabled during the initialization
• Before doing a reinitialization with a changed baud rate or frame format, be sure that there are no ongoing
transmissions while the registers are changed
One-Wire Half-Duplex Mode:
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1.
2.
3.
4.
5.
6.
Internally connect the TXD to the USART receiver (the LBME bit in the USARTn.CTRLA register).
Enable internal pull-up for the RX/TX pin (the PULLUPEN bit in the PORTx.PINnCTRL register).
Enable Open-Drain mode (the ODME bit in the USARTn.CTRLB register).
Set the baud rate (USARTn.BAUD).
Set the frame format and mode of operation (USARTn.CTRLC).
Enable the transmitter and the receiver (USARTn.CTRLB).
Notes:
• When Open-Drain mode is enabled, the TXD pin is automatically set to output by hardware
• For interrupt-driven USART operation, global interrupts must be disabled during the initialization
• Before doing a reinitialization with a changed baud rate or frame format, be sure that there are no ongoing
transmissions while the registers are changed
24.3.2
Operation
24.3.2.1 Frame Formats
The USART data transfer is frame-based. A frame starts with a Start bit followed by one character of data bits. If
enabled, the Parity bit is inserted after the data bits and before the first Stop bit. After the Stop bit(s) of a frame, either
the next frame can follow immediately, or the communication line can return to the Idle (high) state. The USART
accepts all combinations of the following as valid frame formats:
•
•
•
•
1 Start bit
5, 6, 7, 8, or 9 data bits
No, even, or odd Parity bit
1 or 2 Stop bits
The figure below illustrates the possible combinations of frame formats. Bits inside brackets are optional.
Figure 24-2. Frame Formats
FRAME
(IDLE)
St
0
1
2
3
4
[5]
[6]
[7]
[8]
[P]
Sp1 [Sp2]
St
Start bit, always low
(n)
Data bits (0 to 8)
P
Parity bit, may be odd or even
Sp
Stop bit, always high
IDLE
No transfer on the communication line (RxD or TxD). The Idle state is always high.
(St/IDLE)
24.3.2.2 Clock Generation
The clock used for shifting and sampling data bits is generated internally by the fractional baud rate generator or
externally from the Transfer Clock (XCK) pin.
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Figure 24-3. Clock Generation Logic Block Diagram
CLOCK GENERATOR
Sync
Register
Edge
Detector
CLK_PER
Fractional Baud Rate
Generator
BAUD
XCK
XCKO
Transmitter
TXCLK
Receiver
RXCLK
24.3.2.2.1 The Fractional Baud Rate Generator
In modes where the USART is not using the XCK input as a clock source, the fractional Baud Rate Generator is used
to generate the clock. Baud rate is given in terms of bits per second (bps) and is configured by writing the
USARTn.BAUD register. The baud rate (fBAUD) is generated by dividing the peripheral clock (fCLK_PER) by a division
factor decided by the BAUD register.
The fractional Baud Rate Generator features hardware that accommodates cases where fCLK_PER is not divisible by
fBAUD. Usually, this situation would lead to a rounding error. The fractional Baud Rate Generator expects the BAUD
register to contain the desired division factor left shifted by six bits, as implemented by the equations in Table 24-1.
The six Least Significant bits (LSbs) will then hold the fractional part of the desired divisor. Use the fractional part of
the BAUD register to dynamically adjust fBAUD to achieve a closer approximation to the desired baud rate.
Since the baud rate cannot be higher than fCLK_PER, the integer part of the BAUD register needs to be at least 1.
Since the result is left shifted by six bits, the corresponding minimum value of the BAUD register is 64. The valid
range is, therefore, 64 to 65535.
In Synchronous mode, only the 10-bit integer part of the BAUD register (BAUD[15:6]) determines the baud rate, and
the fractional part (BAUD[5:0]) must, therefore, be written to zero.
The table below lists equations for translating baud rates into input values for the BAUD register. The equations
consider fractional interpretation, so the BAUD values calculated with these equations can be written directly to
USARTn.BAUD without any additional scaling.
Table 24-1. Equations for Calculating Baud Rate Register Setting
Operating Mode
Asynchronous
Synchronous Host
Conditions
Baud Rate (Bits Per Seconds) USART.BAUD Register Value
Calculation
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64 × ����_���
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���� =
����� ≤
����_���
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����� =
�
� × ���� 15: 6
���� 15: 6 =
�����.���� ≥ 64
�����.���� ≥ 64
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64 × ����_���
� × �����
����_���
� × �����
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USART - Universal Synchronous and Asynchrono...
S is the number of samples per bit
• Asynchronous Normal mode: S = 16
• Asynchronous Double-Speed mode: S = 8
• Synchronous mode: S = 2
24.3.2.3 Data Transmission
The USART transmitter sends data by periodically driving the transmission line low. The data transmission is initiated
by loading the Transmit Data (USARTn.TXDATAL and USARTn.TXDATAH) registers with the data to be sent. The
data in the Transmit Data registers are moved to the TX Buffer once it is empty and onwards to the Shift register once
it is empty and ready to send a new frame. After the Shift register is loaded with data, the data frame will be
transmitted.
When the entire frame in the Shift register has been shifted out, and there are no new data present in the Transmit
Data registers or the TX Buffer, the Transmit Complete Interrupt Flag (the TXCIF bit in the USARTn.STATUS register)
is set, and the interrupt is generated if it is enabled.
The Transmit Data registers can only be written when the Data Register Empty Interrupt Flag (the DREIF bit in the
USARTn.STATUS register) is set, indicating that they are empty and ready for new data.
When using frames with fewer than eight bits, the Most Significant bits (MSb) written to the Transmit Data registers
are ignored. When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to
9-bit (low byte first), the Transmit Data Register Low Byte (TXDATAL) must be written before the Transmit Data
Register High Byte (TXDATAH). When CHSIZE is configured to 9-bit (high byte first), TXDATAH must be written
before TXDATAL.
24.3.2.3.1 Disabling the Transmitter
When disabling the transmitter, the operation will not become effective until ongoing and pending transmissions are
completed. That is, when the Transmit Shift register, Transmit Data (USARTn.TXDATAL and USARTn.TXDATAH)
registers, and TX Buffer register do not contain data to be transmitted. When the transmitter is disabled, it will no
longer override the TXD pin, and the PORT module regains control of the pin. The pin is automatically configured as
an input by hardware regardless of its previous setting. The pin can now be used as a normal I/O pin with no port
override from the USART.
24.3.2.4 Data Reception
The USART receiver samples the reception line to detect and interpret the received data. The direction of the pin
must, therefore, be configured as an input by writing a ‘0’ to the corresponding bit in the Data Direction (PORTx.DIR)
register.
The receiver accepts data when a valid Start bit is detected. Each bit that follows the Start bit will be sampled at the
baud rate or XCK clock and shifted into the Receive Shift register until the first Stop bit of a frame is received. A
second Stop bit will be ignored by the receiver. When the first Stop bit is received, and a complete serial frame is
present in the Receive Shift register, the contents of the Shift register will be moved into the receive buffer. The
Receive Complete Interrupt Flag (the RXCIF bit in the USARTn.STATUS register) is set, and the interrupt is
generated if enabled.
The RXDATA registers are the part of the double-buffered RX buffer that can be read by the application software
when RXCIF is set. If only one frame has been received, the data and status bits for that frame are pushed to the
RXDATA registers directly. If two frames are present in the RX buffer, the RXDATA registers contain the data for the
oldest frame.
The buffer shifts out the data either when RXDATAL or RXDATAH is read, depending on the configuration. The
register, which does not lead to data being shifted, must be read first to be able to read both bytes before shifting.
When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to 9-bit (low
byte first), a read of RXDATAH shifts the receive buffer. Otherwise, RXDATAL shifts the buffer.
24.3.2.4.1 Receiver Error Flags
The USART receiver features error detection mechanisms that uncover any corruption of the transmission. These
mechanisms include the following:
• Frame Error detection - controls whether the received frame is valid
• Buffer Overflow detection - indicates data loss due to the receiver buffer being full and overwritten by the new
data
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•
Parity Error detection - checks the validity of the incoming frame by calculating its parity and comparing it to the
Parity bit
Each error detection mechanism controls one error flag that can be read in the RXDATAH register:
• Frame Error (FERR)
• Buffer Overflow (BUFOVF)
• Parity Error (PERR)
The error flags are located in the RX buffer together with their corresponding frame. The RXDATAH register that
contains the error flags must be read before the RXDATAL register since reading the RXDATAL register will trigger
the RX buffer to shift out the RXDATA bytes.
Note: If the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is set to nine bits, low byte
first (9BITL), the RXDATAH register will, instead of the RXDATAL register, trigger the RX buffer to shift out the
RXDATA bytes. The RXDATAL register must, in that case, be read before the RXDATAH register.
24.3.2.4.2 Disabling the Receiver
When disabling the receiver, the operation is immediate. The receiver buffer will be flushed, and data from ongoing
receptions will be lost.
24.3.2.4.3 Flushing the Receive Buffer
If the RX buffer has to be flushed during normal operation, repeatedly read the DATA location (USARTn.RXDATAH
and USARTn.RXDATAL registers) until the Receive Complete Interrupt Flag (the RXCIF bit in the
USARTn.RXDATAH register) is cleared.
24.3.3
Communication Modes
The USART is a flexible peripheral that supports multiple different communication protocols. The available modes of
operation can be split into two groups: Synchronous and asynchronous communication.
The synchronous communication relies on one device on the bus to be the host, providing the rest of the devices with
a clock signal through the XCK pin. All the devices use this common clock signal for both transmission and reception,
requiring no additional synchronization mechanism.
The device can be configured to run either as a host or a client on the synchronous bus.
The asynchronous communication does not use a common clock signal. Instead, it relies on the communicating
devices to be configured with the same baud rate. When receiving a transmission, the hardware synchronization
mechanisms are used to align the incoming transmission with the receiving device peripheral clock.
Four different modes of reception are available when communicating asynchronously. One of these modes can
receive transmissions at twice the normal speed, sampling only eight times per bit instead of the normal 16. The
other three operating modes use variations of synchronization logic, all receiving at normal speed.
24.3.3.1 Synchronous Operation
24.3.3.1.1 Clock Operation
The XCK pin direction controls whether the transmission clock is an input (Client mode) or an output (Host mode).
The corresponding port pin direction must be set to output for Host mode or input for Client mode (PORTx.DIRn). The
data input (on RXD) is sampled at the XCK clock edge, which is opposite the edge where data are transmitted (on
TXD), as shown in the figure below.
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Figure 24-4. Synchronous Mode XCK Timing
XCK
INVEN = 0
Data transmit (TxD)
Data sample (RxD)
XCK
INVEN = 1
Data transmit (TxD)
Data sample (RxD)
The I/O pin can be inverted by writing a ‘1’ to the Inverted I/O Enable (INVEN) bit in the Pin n Control register of the
port peripheral (PORTx.PINnCTRL). When using the inverted I/O setting for the corresponding XCK port pin, the XCK
clock edges used for sampling RxD and transmitting on TxD can be selected. If the inverted I/O is disabled (INVEN =
0), the rising XCK clock edge represents the start of a new data bit, and the received data will be sampled at the
falling XCK clock edge. If inverted I/O is enabled (INVEN = 1), the falling XCK clock edge represents the start of a
new data bit, and the received data will be sampled at the rising XCK clock edge.
24.3.3.1.2 External Clock Limitations
When the USART is configured in Synchronous Client mode, the XCK signal must be provided externally by the host
device. Since the clock is provided externally, configuring the BAUD register will have no impact on the transfer
speed. Successful clock recovery requires the clock signal to be sampled at least twice for each rising and falling
edge. The maximum XCK speed in Synchronous Operation mode, fClient_XCK, is therefore limited by:
�������_XCK<
����_���
4
If the XCK clock has jitter, or if the high/low period duty cycle is not 50/50, the maximum XCK clock speed must be
reduced accordingly to ensure that XCK is sampled a minimum of two times for each edge.
24.3.3.1.3 USART in Host SPI Mode
The USART may be configured to function with multiple different communication interfaces, and one of these is the
Serial Peripheral Interface (SPI), where it can work as the host device. The SPI is a four-wire interface that enables a
host device to communicate with one or multiple clients.
Frame Formats
The serial frame for the USART in Host SPI mode always contains eight Data bits. The Data bits can be configured to
be transmitted with either the LSb or MSb first by writing to the Data Order (UDORD) bit in the Control C
(USARTn.CTRLC) register.
SPI does not use Start, Stop, or Parity bits, so the transmission frame can only consist of the Data bits.
Clock Generation
Being a host device in a synchronous communication interface, the USART in Host SPI mode must generate the
interface clock to be shared with the client devices. The interface clock is generated using the fractional Baud Rate
Generator, which is described in 24.3.2.2.1 The Fractional Baud Rate Generator.
Each Data bit is transmitted by pulling the data line high or low for one full clock period. The receiver will sample bits
in the middle of the transmitter hold period, as shown in the figure below. It also shows how the timing scheme can be
configured using the Inverted I/O Enable (INVEN) bit in the PORTx.PINnCTRL register and the USART Clock Phase
(UCPHA) bit in the USARTn.CTRLC register.
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UCPHA = 1
UCPHA = 0
Figure 24-5. Data Transfer Timing Diagrams
INVEN = 0
INVEN = 1
XCK
XCK
Data transmit (TxD)
Data transmit (TxD)
Data sample (RxD)
Data sample (RxD)
XCK
XCK
Data transmit (TxD)
Data transmit (TxD)
Data sample (RxD)
Data sample (RxD)
The table below further explains the figure above.
Table 24-2. Functionality of the INVEN and UCPHA Bits
INVEN
UCPHA
Leading Edge (1)
Trailing Edge (1)
0
0
Rising, sample
Falling, transmit
0
1
Rising, transmit
Falling, sample
1
0
Falling, sample
Rising, transmit
1
1
Falling, transmit
Rising, sample
Note:
1. The leading edge is the first clock edge of a clock cycle. The trailing edge is the last clock edge of a clock
cycle.
Data Transmission
Data transmission in Host SPI mode is functionally identical to the general USART operation, as described in the
Operation section. The transmitter interrupt flags and corresponding USART interrupts are also identical. See
24.3.2.3 Data Transmission for further description.
Data Reception
Data reception in Host SPI mode is identical in function to general USART operation as described in the Operation
section. The receiver interrupt flags and the corresponding USART interrupts are also identical, except for the
receiver error flags that are not in use and always read as ‘0’. See 24.3.2.4 Data Reception for further description.
USART in Host SPI Mode vs. SPI
The USART in Host SPI mode is fully compatible with a stand-alone SPI peripheral. Their data frame and timing
configurations are identical. Some SPI specific special features are, however, not supported with the USART in Host
SPI mode:
• Write Collision Flag Protection
• Double-Speed mode
• Multi-Host support
A comparison of the pins used with USART in Host SPI mode and with SPI is shown in the table below.
Table 24-3. Comparison of USART in Host SPI Mode and SPI Pins
USART
SPI
Comment
TXD
MOSI
Host out
RXD
MISO
Host in
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USART - Universal Synchronous and Asynchrono...
...........continued
USART
SPI
Comment
XCK
SCK
Functionally identical
-
SS
Not supported by USART in Host SPI mode(1)
Note:
1. For the stand-alone SPI peripheral, this pin is used with the Multi-Host function or as a dedicated Client Select
pin. The Multi-Host function is not available with the USART in Host SPI mode, and no dedicated Client Select
pin is available.
24.3.3.2 Asynchronous Operation
24.3.3.2.1 Clock Recovery
Since there is no common clock signal when using Asynchronous mode, each communicating device generates
separate clock signals. These clock signals must be configured to run at the same baud rate for the communication
to take place. The devices, therefore, run at the same speed, but their timing is skewed in relation to each other. To
accommodate this, the USART features a hardware clock recovery unit which synchronizes the incoming
asynchronous serial frames with the internally generated baud rate clock.
The figure below illustrates the sampling process for the Start bit of an incoming frame. It shows the timing scheme
for both Normal and Double-Speed mode (the RXMODE bit field in the USARTn.CTRLB register configured
respectively to 0x00 and 0x01). The sample rate for Normal mode is 16 times the baud rate, while the sample rate
for Double-Speed mode is eight times the baud rate (see 24.3.3.2.4 Double-Speed Operation for more details). The
horizontal arrows show the maximum synchronization error. Note that the maximum synchronization error is larger in
Double-Speed mode.
Figure 24-6. Start Bit Sampling
RxD
IDLE
START
BIT 0
Sample
(RXMODE = 0x0 )
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
Sample
(RXMODE = 0x1 )
0
1
2
3
4
5
6
7
8
1
2
When the clock recovery logic detects a falling edge from the Idle (high) state to the Start bit (low), the Start bit
detection sequence is initiated. In the figure above, sample 1 denotes the first sample reading ‘0’. The clock recovery
logic then uses three subsequent samples (samples 8, 9, and 10 in Normal mode, and samples 4, 5, 6 in DoubleSpeed mode) to decide if a valid Start bit is received. If two or three samples read ‘0’, the Start bit is accepted. The
clock recovery unit is synchronized, and the data recovery can begin. If less than two samples read ‘0’, the Start bit is
rejected. This process is repeated for each Start bit.
24.3.3.2.2 Data Recovery
As with clock recovery, the data recovery unit samples at a rate 8 or 16 times faster than the baud rate depending on
whether it is running in Double-Speed or Normal mode, respectively. The figure below shows the sampling process
for reading a bit in a received frame.
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Figure 24-7. Sampling of Data and Parity Bits
RxD
BIT n
Sample
1
(CLK2X = 0)
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
Sample
1
(CLK2X = 1)
2
3
4
5
6
7
8
1
A majority voting technique is, like with clock recovery, used on the three center samples for deciding the logic level
of the received bit. The process is repeated for each bit until a complete frame is received.
The data recovery unit will only receive the first Stop bit while ignoring the rest if there are more. If the sampled Stop
bit is read ‘0’, the Frame Error flag will be set. The figure below shows the sampling of a Stop bit. It also shows the
earliest possible beginning of the next frame's Start bit.
Figure 24-8. Stop Bit and Next Start Bit Sampling
RxD
STOP 1
(A)
(B)
(C)
Sample
1
(CLK2X = 0)
2
3
4
5
6
7
8
9
10
0/1
0/1
0/1
Sample
1
(CLK2X = 1)
2
3
4
5
6
0/1
A new high-to-low transition indicating the Start bit of a new frame can come right after the last of the bits used for
majority voting. For Normal-Speed mode, the first low-level sample can be at the point marked (A) in the figure
above. For Double-Speed mode, the first low level must be delayed to point (B), being the first sample after the
majority vote samples. Point (C) marks a Stop bit of full length at the nominal baud rate.
24.3.3.2.3 Error Tolerance
The speed of the internally generated baud rate and the externally received data rate has to be identical, but, due to
natural clock source error, this is usually not the case. The USART is tolerant of such error, and the limits of this
tolerance make up what is sometimes known as the Operational Range.
The following tables list the operational range of the USART, being the maximum receiver baud rate error that can be
tolerated. Note that Normal-Speed mode has higher toleration of baud rate variations than Double-Speed mode.
Table 24-4. Recommended Maximum Receiver Baud Rate Error for Normal-Speed Mode
D
Rslow [%]
Rfast [%]
Maximum Total Error [%]
Recommended Max. Receiver Error [%]
5
93.20
106.67
-6.80/+6.67
±3.0
6
94.12
105.79
-5.88/+5.79
±2.5
7
94.81
105.11
-5.19/+5.11
±2.0
8
95.36
104.58
-4.54/+4.58
±2.0
9
95.81
104.14
-4.19/+4.14
±1.5
10
96.17
103.78
-3.83/+3.78
±1.5
Notes:
• D: The sum of character size and parity size (D = 5 to 10 bits)
• RSLOW: The ratio of the slowest incoming data rate that can be accepted in relation to the receiver baud rate
• RFAST: The ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud rate
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Table 24-5. Recommended Maximum Receiver Baud Rate Error for Double-Speed Mode
D
Rslow [%]
Rfast [%]
Maximum Total Error [%]
Recommended Max. Receiver Error [%]
5
94.12
105.66
-5.88/+5.66
±2.5
6
94.92
104.92
-5.08/+4.92
±2.0
7
95.52
104.35
-4.48/+4.35
±1.5
8
96.00
103.90
-4.00/+3.90
±1.5
9
96.39
103.53
-3.61/+3.53
±1.5
10
96.70
103.23
-3.30/+3.23
±1.0
Notes:
• D: The sum of character size and parity size (D = 5 to 10 bits)
• RSLOW: The ratio of the slowest incoming data rate that can be accepted in relation to the receiver baud rate
• RFAST: The ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud rate
The recommendations of the maximum receiver baud rate error were made under the assumption that the receiver
and transmitter equally divide the maximum total error.
The following equations are used to calculate the maximum ratio of the incoming data rate and the internal receiver
baud rate.
����� =
•
•
•
•
•
•
� �+1
� � + 1 + �� − 1
����� =
� �+2
� � + 1 + ��
D: The sum of character size and parity size (D = 5 to 10 bits)
S: Samples per bit. S = 16 for Normal-Speed mode and S = 8 for Double-Speed mode.
SF: First sample number used for majority voting. SF = 8 for Normal-Speed mode and SF = 4 for Double-Speed
mode.
SM: Middle sample number used for majority voting. SM = 9 for Normal-Speed mode and SM = 5 for DoubleSpeed mode.
RSLOW: The ratio of the slowest incoming data rate that can be accepted in relation to the receiver baud rate
RFAST: The ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud rate
24.3.3.2.4 Double-Speed Operation
The double-speed operation allows for higher baud rates under asynchronous operation with lower peripheral clock
frequencies. This operation mode is enabled by writing the RXMODE bit field in the Control B (USARTn.CTRLB)
register to 0x01.
When enabled, the baud rate for a given asynchronous baud rate setting will be doubled, as shown in the equations
in 24.3.2.2.1 The Fractional Baud Rate Generator. In this mode, the receiver will use half the number of samples
(reduced from 16 to 8) for data sampling and clock recovery. This requires a more accurate baud rate setting and
peripheral clock. See 24.3.3.2.3 Error Tolerance for more details.
24.3.3.2.5 Auto-Baud
The auto-baud feature lets the USART configure its BAUD register based on input from a communication device,
which allows the device to communicate autonomously with multiple devices communicating with different baud
rates. The USART peripheral features two auto-baud modes: Generic Auto-Baud mode and LIN Constrained AutoBaud mode.
Both auto-baud modes must receive an auto-baud frame, as seen in the figure below.
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Figure 24-9. Auto-Baud Timing
Break Field
Sync Field
Tbit
8 Tbit
The break field is detected when 12 or more consecutive low cycles are sampled and notifies the USART that it is
about to receive the synchronization field. After the break field, when the Start bit of the synchronization field is
detected, a counter running at the peripheral clock speed is started. The counter is then incremented for the next
eight Tbit of the synchronization field. When all eight bits are sampled, the counter is stopped. The resulting counter
value is in effect the new BAUD register value.
When the USART Receive mode is set to GENAUTO (the RXMODE bit field in the USARTn.CTRLB register), the
Generic Auto-Baud mode is enabled. In this mode, one can set the Wait For Break (WFB) bit in the USARTn.STATUS
register to enable detection of a break field of any length (that is, also shorter than 12 cycles). This makes it possible
to set an arbitrary new baud rate without knowing the current baud rate. If the measured sync field results in a valid
BAUD value (0x0064 - 0xFFFF), the BAUD register is updated.
When USART Receive mode is set to LINAUTO mode (the RXMODE bit field in the USARTn.CTRLB register), it
follows the LIN format. The WFB functionality of the Generic Auto-Baud mode is not compatible with the LIN
Constrained Auto-Baud mode, which means that the received signal must be low for 12 peripheral clock cycles or
more for a break field to be valid. When a break field has been detected, the USART expects the following
synchronization field character to be 0x55. If the received synchronization field character is not 0x55, the
Inconsistent Sync Field Error Flag (the ISFIF bit in the USARTn.STATUS register) is set, and the baud rate is
unchanged.
24.3.3.2.6 Half-Duplex Operation
Half-duplex is a type of communication where two or more devices may communicate with each other, but only one at
a time. The USART can be configured to operate in the following half-duplex modes:
• One-Wire mode
• RS-485 mode
One-Wire Mode
One-Wire mode is enabled by setting the Loop-Back Mode Enable (LBME) bit in the USARTn.CTRLA register. This
will enable an internal connection between the TXD pin and the USART receiver, making the TXD pin a combined
TxD/RxD line. The RXD pin will be disconnected from the USART receiver and may be controlled by a different
peripheral.
In One-Wire mode, multiple devices can manipulate the TxD/RxD line at the same time. In the case where one
device drives the pin to a logical high level (VCC), and another device pulls the line low (GND), a short will occur. To
accommodate this, the USART features an Open-Drain mode (the ODME bit in the USARTn.CTRLB register), which
prevents the transmitter from driving a pin to a logical high level, thereby constraining it to only be able to pull it low.
Combining this function with the internal pull-up feature (the PULLUPEN bit in the PORTx.PINnCTRL register) will let
the line be held high through a pull-up resistor, allowing any device to pull it low. When the line is pulled low, the
current from VCC to GND will be limited by the pull-up resistor. The TXD pin is automatically set to output by hardware
when the Open-Drain mode is enabled.
When the USART is transmitting to the TxD/RxD line, it will also receive its transmission. This can be used to detect
overlapping transmissions by checking if the received data are the same as the transmitted data.
RS-485 Mode
RS-485 is a communication standard supported by the USART peripheral. It is a physical interface that defines the
setup of a communication circuit. Data are transmitted using differential signaling, making communication robust
against noise. RS-485 is enabled by writing to the RS485 bit field in the USARTn.CTRLA register.
The RS-485 mode supports external line driver devices that convert a single USART transmission into corresponding
differential pair signals. Writing RS485[0] to ‘1’ enables the automatic control of the XDIR pin that can be used to
enable transmission or reception for the line driver device. The USART automatically drives the XDIR pin high while
the USART is transmitting and pulls it low when the transmission is complete. An example of such a circuit is shown
in the figure below.
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Figure 24-10. RS-485 Bus Connection
Line Driver
TXD
TX Driver
XDIR
Differential Bus
+
-
USART
RX Driver
RXD
The XDIR pin goes high one baud clock cycle in advance of data being shifted out to allow some guard time to
enable the external line driver. The XDIR pin will remain high for the complete frame, including Stop bit(s).
Figure 24-11. XDIR Drive Timing
TxD
St
0
1
2
3
4
5
6
7
Sp1
XDIR
Guard
time
Stop
Writing RS485[1] to ‘1’ enables the RS-485 mode, which automatically sets the TXD pin to output one clock cycle
before starting transmission and sets it back to input when the transmission is complete.
RS-485 mode is compatible with One-Wire mode. One-Wire mode enables an internal connection between the TXD
pin and the USART receiver, making the TXD pin a combined TxD/RxD line. The RXD pin will be disconnected from
the USART receiver and may be controlled by a different peripheral. An example of such a circuit is shown in the
figure below.
Figure 24-12. RS-485 with Loop-Back Mode Connection
TXD
Line Driver
TX Driver
XDIR
Differential Bus
+
-
USART
RXD
RX Driver
24.3.3.2.7 IRCOM Mode of Operation
The USART peripheral can be configured in Infrared Communication mode (IRCOM), which is IrDA® 1.4 compatible
with baud rates up to 115.2 kbps. When enabled, the IRCOM mode enables infrared pulse encoding/decoding for the
USART.
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Figure 24-13. Block Diagram
IRCOM
Event System
Events
Encoded RxD
Pulse
Decoding
Decoded RxD
USART
TXD
Decoded RxD
Pulse
Encoding
RXD
Encoded RxD
The USART is set in IRCOM mode by writing 0x02 to the CMODE bit field in the USARTn.CTRLC register. The data
on the TXD/RXD pins are the inverted values of the transmitted/received infrared pulse. It is also possible to select an
event channel from the Event System as an input for the IRCOM receiver. This enables the IRCOM to receive input
from the I/O pins or sources other than the corresponding RXD pin, which will disable the RxD input from the USART
pin.
For transmission, three pulse modulation schemes are available:
•
•
•
3/16 of the baud rate period
Fixed programmable pulse time based on the peripheral clock frequency
Pulse modulation disabled
For the reception, a fixed programmable minimum high-level pulse-width for the pulse to be decoded as a logical ‘0’
is used. Shorter pulses will then be discarded, and the bit will be decoded to logical ‘1’ as if no pulse was received.
Double-Speed mode cannot be used for the USART when IRCOM mode is enabled.
24.3.4
Additional Features
24.3.4.1 Parity
Parity bits can be used by the USART to check the validity of a data frame. The Parity bit is set by the transmitter
based on the number of bits with the value of ‘1’ in a transmission and controlled by the receiver upon reception. If
the Parity bit is inconsistent with the transmission frame, the receiver may assume that the data frame has been
corrupted.
Even or odd parity can be selected for error checking by writing the Parity Mode (PMODE) bit field in the
USARTn.CTRLC register. If even parity is selected, the Parity bit is set to ‘1’ if the number of Data bits with value ‘1’
is odd (making the total number of bits with value ‘1’ even). If odd parity is selected, the Parity bit is set to ‘1’ if the
number of data bits with value ‘1’ is even (making the total number of bits with value ‘1’ odd).
When enabled, the parity checker calculates the parity of the data bits in incoming frames and compares the result
with the Parity bit of the corresponding frame. If a parity error is detected, the Parity Error flag (the PERR bit in the
USARTn.RXDATAH register) is set.
If LIN Constrained Auto-Baud mode is enabled (RXMODE = 0x03 in the USARTn.CTRLB register), a parity check is
performed only on the protected identifier field. A parity error is detected if one of the equations below is not true,
which sets the Parity Error flag.
�0 = ��0 XOR ��1 XOR ��2 XOR ��4
�1 = NOT ��1 XOR ��3 XOR ��4 XOR ��5
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Figure 24-14. Protected Identifier Field and Mapping of Identifier and Parity Bits
Protected identifier field
St
ID0 ID1 ID2 ID3 ID4 ID5 P0
P1
Sp
24.3.4.2 Start-of-Frame Detection
The Start-of-Frame Detection feature enables the USART to wake up from Standby sleep mode upon data reception.
When a high-to-low transition is detected on the RXD pin, the oscillator is powered up, and the USART peripheral
clock is enabled. After start-up, the rest of the data frame can be received, provided that the baud rate is slow enough
concerning the oscillator start-up time. The start-up time of the oscillators varies with supply voltage and temperature.
For details on oscillator start-up time characteristics, refer to the Electrical Characteristics section.
If a false Start bit is detected, the device will, if another wake-up source has not been triggered, go back into the
Standby sleep mode.
The Start-of-Frame detection works in Asynchronous mode only. It is enabled by writing the Start-of-Frame Detection
Enable (SFDEN) bit in the USARTn.CTRLB register. If a Start bit is detected while the device is in Standby sleep
mode, the USART Receive Start Interrupt Flag (RXSIF) bit is set.
The USART Receive Complete Interrupt Flag (RXCIF) bit and the RXSIF bit share the same interrupt line, but each
has its dedicated interrupt settings. The table below shows the USART Start Frame Detection modes, depending on
the interrupt setting.
Table 24-6. USART Start Frame Detection Modes
SFDEN RXSIF Interrupt RXCIF Interrupt Comment
0
x
x
Standard mode
1
Disabled
Disabled
Only the oscillator is powered during the frame reception. If the
interrupts are disabled and buffer overflow is ignored, all incoming
frames will be lost
1
Disabled
Enabled
System/all clocks are awakened on Receive Complete interrupt
1
Enabled
x
System/all clocks are awakened when a Start bit is detected
Note: The SLEEP instruction will not shut down the oscillator if there is ongoing communication.
24.3.4.3 Multiprocessor Communication
The Multiprocessor Communication mode (MPCM) effectively reduces the number of incoming frames that have to
be handled by the receiver in a system with multiple microcontrollers communicating via the same serial bus. This
mode is enabled by writing a ‘1’ to the MPCM bit in the Control B (USARTn.CTRLB) register. In this mode, a
dedicated bit in the frames is used to indicate whether the frame is an address or data frame type.
If the receiver is set up to receive frames that contain five to eight data bits, the first Stop bit is used to indicate the
frame type. If the receiver is set up for frames with nine data bits, the ninth bit is used to indicate frame type. When
the frame type bit is ‘1’, the frame contains an address. When the frame type bit is ‘0’, the frame is a data frame. If 5to 8-bit character frames are used, the transmitter must be set to use two Stop bits since the first Stop bit is used for
indicating the frame type.
If a particular client MCU has been addressed, it will receive the following data frames as usual, while the other client
MCUs will ignore the frames until another address frame is received.
24.3.4.3.1 Using Multiprocessor Communication
Use the following procedure to exchange data in Multiprocessor Communication mode (MPCM):
1.
2.
3.
All client MCUs are in Multiprocessor Communication mode.
The host MCU sends an address frame, and all clients receive and read this frame.
Each client MCU determines if it has been selected.
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4.
The addressed MCU will disable MPCM and receive all data frames. The other client MCUs will ignore the
data frames.
When the addressed MCU has received the last data frame, it must enable MPCM again and wait for a new
address frame from the host.
5.
The process then repeats from step 2.
24.3.5
Events
The USART can generate the events described in the table below.
Table 24-7. Event Generators in USART
Generator Name
Description
Peripheral Event
USARTn
XCK
The clock signal in SPI Host mode
and Synchronous USART Host
mode
Event Type
Generating Clock
Domain
Length of Event
Pulse
CLK_PER
One XCK period
The table below describes the event user and its associated functionality.
Table 24-8. Event Users in USART
User Name
24.3.6
Peripheral
Input
USARTn
IREI
Description
USARTn IrDA event input
Input Detection
Async/Sync
Pulse
Sync
Interrupts
Table 24-9. Available Interrupt Vectors and Sources
Name Vector Description
Conditions
RXC
Receive Complete interrupt
•
•
•
There is unread data in the receive buffer (RXCIE)
Receive of Start-of-Frame detected (RXSIE)
Auto-Baud Error/ISFIF flag set (ABEIE)
DRE
Data Register Empty
interrupt
The transmit buffer is empty/ready to receive new data (DREIE)
TXC
Transmit Complete
interrupt
The entire frame in the Transmit Shift register has been shifted out and there
are no new data in the transmit buffer (TXCIE)
When an Interrupt condition occurs, the corresponding Interrupt flag is set in the STATUS (USARTn.STATUS)
register.
An interrupt source is enabled or disabled by writing to the corresponding bit in the Control A (USARTn.CTRLA)
register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the Interrupt flag is set.
The interrupt request remains active until the Interrupt flag is cleared. See the USARTn.STATUS register for details
on how to clear Interrupt flags.
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24.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x07
RXDATAL
RXDATAH
TXDATAL
TXDATAH
STATUS
CTRLA
CTRLB
CTRLC
CTRLC
0x08
BAUD
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
15:8
0x0A
0x0B
0x0C
0x0D
0x0E
Reserved
DBGCTRL
EVCTRL
TXPLCTRL
RXPLCTRL
24.5
7
6
RXCIF
BUFOVF
5
4
3
2
1
0
FERR
PERR
DATA[8]
DATA[7:0]
DATA[7:0]
RXCIF
TXCIF
RXCIE
TXCIE
RXEN
TXEN
CMODE[1:0]
CMODE[1:0]
7:0
7:0
7:0
7:0
DREIF
DREIE
RXSIF
RXSIE
SFDEN
PMODE[1:0]
ISFIF
LBME
ODME
SBMODE
DATA[8]
BDF
WFB
ABEIE
RS485[1:0]
RXMODE[1:0]
MPCM
CHSIZE[2:0]
UDORD
UCPHA
BAUD[7:0]
BAUD[15:8]
DBGRUN
IREI
TXPL[7:0]
RXPL[6:0]
Register Description
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24.5.1
Receiver Data Register Low Byte
Name:
Offset:
Reset:
Property:
RXDATAL
0x00
0x00
-
This register contains the eight LSbs of the data received by the USART receiver. The USART receiver is doublebuffered, and this register always represents the data for the oldest received frame. If the data for only one frame is
present in the receive buffer, this register contains that data.
The buffer shifts out the data either when RXDATAL or RXDATAH is read, depending on the configuration. The
register, which does not lead to data being shifted, must be read first to be able to read both bytes before shifting.
When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to 9-bit (low
byte first), a read of RXDATAH shifts the receive buffer, or else, RXDATAL shifts the buffer.
Bit
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
DATA[7:0]
Access
Reset
R
0
R
0
R
0
R
0
Bits 7:0 – DATA[7:0] Receiver Data Register
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24.5.2
Receiver Data Register High Byte
Name:
Offset:
Reset:
Property:
RXDATAH
0x01
0x00
-
This register contains the MSb of the data received by the USART receiver, as well as status bits reflecting the status
of the received data frame. The USART receiver is double-buffered, and this register always represents the data and
status bits for the oldest received frame. If the data and status bits for only one frame is present in the receive buffer,
this register contains that data.
The buffer shifts out the data either when RXDATAL or RXDATAH is read, depending on the configuration. The
register, which does not lead to data being shifted, must be read first to be able to read both bytes before shifting.
When the Character Size (CHSIZE) bits in the Control C (USARTn.CTRLC) register is configured to 9-bit (low byte
first), a read of RXDATAH shifts the receive buffer, or else, RXDATAL shifts the buffer.
Bit
Access
Reset
7
RXCIF
R
0
6
BUFOVF
R
0
5
4
3
2
FERR
R
0
1
PERR
R
0
0
DATA[8]
R
0
Bit 7 – RXCIF USART Receive Complete Interrupt Flag
This flag is set when there are unread data in the receive buffer and cleared when the receive buffer is empty.
Bit 6 – BUFOVF Buffer Overflow
This flag is set if a buffer overflow is detected. A buffer overflow occurs when the receive buffer is full, a new frame is
waiting in the receive shift register, and a new Start bit is detected. This flag is cleared when the Receiver Data
(USARTn.RXDATAL and USARTn.RXDATAH) registers are read.
This flag is not used in the Host SPI mode of operation.
Bit 2 – FERR Frame Error
This flag is set if the first Stop bit is ‘0’ and cleared when it is correctly read as ‘1’.
This flag is not used in the Host SPI mode of operation.
Bit 1 – PERR Parity Error
This flag is set if parity checking is enabled and the received data has a parity error, or else, this flag cleared. For
details on parity calculation, refer to 24.3.4.1 Parity.
This flag is not used in the Host SPI mode of operation.
Bit 0 – DATA[8] Receiver Data Register
When using a 9-bit frame size, this bit holds the ninth bit (MSb) of the received data.
When the Receiver Mode (RXMODE) bit field in the Control B (USARTn.CTRLB) register is configured to LIN
Constrained Auto-Baud (LINAUTO) mode, this bit indicates if the received data are within the response space of a
LIN frame. This bit is cleared if the received data are in the protected identifier field and is otherwise set.
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24.5.3
Transmit Data Register Low Byte
Name:
Offset:
Reset:
Property:
TXDATAL
0x02
0x00
-
The data written to this register is automatically loaded into the TX Buffer and through to the dedicated Shift register.
The shift register outputs each of the bits serially to the TXD pin.
When using a 9-bit frame size, the ninth bit (MSb) must be written to the Transmit Data Register High Byte
(USARTn.TXDATAH). In that case, the buffer shifts data either when the Transmit Data Register Low Byte
(USARTn.TXDATAL) or the Transmit Data Register High Byte (USARTn.TXDATAH) is written, depending on the
configuration. The register, which does not lead to data being shifted, must be written first to be able to write both
registers before shifting.
When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to 9-bit (low
byte first), a write of the Transmit Data Register High Byte shifts the transmit buffer. Otherwise, the Transmit Data
Register Low Byte shifts the buffer.
This register may only be written when the Data Register Empty Interrupt Flag (DREIF) in the Status
(USARTn.STATUS) register is set.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DATA[7:0] Transmit Data Register Low Byte
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24.5.4
Transmit Data Register High Byte
Name:
Offset:
Reset:
Property:
TXDATAH
0x03
0x00
-
The data written to this register is automatically loaded into the TX Buffer and through to the dedicated Shift register.
The shift register outputs each of the bits serially to the TXD pin.
When using a 9-bit frame size, the ninth bit (MSb) must be written to the Transmit Data Register High Byte
(USARTn.TXDATAH). In that case, the buffer shifts data either when the Transmit Data Register Low Byte
(USARTn.TXDATAL) or the Transmit Data Register High Byte (USARTn.TXDATAH) is written, depending on the
configuration. The register, which does not lead to data being shifted, must be written first to be able to write both
registers before shifting.
When the Character Size (CHSIZE) bit field in the Control C (USARTn.CTRLC) register is configured to 9-bit (low
byte first), a write of the Transmit Data Register High Byte shifts the transmit buffer. Otherwise, the Transmit Data
Register Low Byte shifts the buffer.
This register may only be written when the Data Register Empty Interrupt Flag (DREIF) in the Status
(USARTn.STATUS) register is set.
Bit
7
6
5
4
3
Access
Reset
2
1
0
DATA[8]
R/W
0
Bit 0 – DATA[8] Transmit Data Register High Byte
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24.5.5
USART Status Register
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RXCIF
R
0
STATUS
0x04
0x00
-
6
TXCIF
R/W
0
5
DREIF
R
1
4
RXSIF
R/W
0
3
ISFIF
R/W
0
2
1
BDF
R/W
0
0
WFB
W
0
Bit 7 – RXCIF USART Receive Complete Interrupt Flag
This flag is set when there are unread data in the receive buffer and cleared when the receive buffer is empty.
Bit 6 – TXCIF USART Transmit Complete Interrupt Flag
This flag is set when the entire frame in the Transmit Shift register has been shifted out, and there are no new data in
the transmit buffer (TXDATAL and TXDATAH) registers. It is cleared by writing a ‘1’ to it.
Bit 5 – DREIF USART Data Register Empty Interrupt Flag
This flag is set when the Transmit Data (USARTn.TXDATAL and USARTn.TXDATAH) registers are empty and
cleared when they contain data that has not yet been moved into the transmit shift register.
Bit 4 – RXSIF USART Receive Start Interrupt Flag
This flag is set when Start-of-Frame detection is enabled, the device is in Standby sleep mode, and a valid start bit is
detected. It is cleared by writing a ‘1’ to it.
This flag is not used in the Host SPI mode operation.
Bit 3 – ISFIF Inconsistent Synchronization Field Interrupt Flag
This flag is set if an auto-baud mode is enabled, and the synchronization field is too short or too long to give a valid
baud setting. It will also be set when USART is set to LINAUTO mode, and the SYNC character differs from data
value 0x55. This flag is cleared by writing a ‘1’ to it. See the Auto-Baud section for more information.
Bit 1 – BDF Break Detected Flag
This flag is set if an auto-baud mode is enabled and a valid break and synchronization character is detected, and is
cleared when the next data are received. It can also be cleared by writing a ‘1’ to it. See the Auto-Baud section for
more information.
Bit 0 – WFB Wait For Break
This bit controls whether the Wait For Break feature is enabled or not. Refer to the Auto-Baud section for more
information.
Value
Description
0
Wait For Break is disabled
1
Wait For Break is enabled
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24.5.6
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RXCIE
R/W
0
CTRLA
0x05
0x00
-
6
TXCIE
R/W
0
5
DREIE
R/W
0
4
RXSIE
R/W
0
3
LBME
R/W
0
2
ABEIE
R/W
0
1
0
RS485[1:0]
R/W
0
R/W
0
Bit 7 – RXCIE Receive Complete Interrupt Enable
This bit controls whether the Receive Complete Interrupt is enabled or not. When enabled, the interrupt will be
triggered when the RXCIF bit in the USARTn.STATUS register is set.
Value
Description
0
The Receive Complete Interrupt is disabled
1
The Receive Complete Interrupt is enabled
Bit 6 – TXCIE Transmit Complete Interrupt Enable
This bit controls whether the Transmit Complete Interrupt is enabled or not. When enabled, the interrupt will be
triggered when the TXCIF bit in the USARTn.STATUS register is set.
Value
Description
0
The Transmit Complete Interrupt is disabled
1
The Transmit Complete Interrupt is enabled
Bit 5 – DREIE Data Register Empty Interrupt Enable
This bit controls whether the Data Register Empty Interrupt is enabled or not. When enabled, the interrupt will be
triggered when the DREIF bit in the USARTn.STATUS register is set.
Value
Description
0
The Data Register Empty Interrupt is disabled
1
The Data Register Empty Interrupt is enabled
Bit 4 – RXSIE Receiver Start Frame Interrupt Enable
This bit controls whether the Receiver Start Frame Interrupt is enabled or not. When enabled, the interrupt will be
triggered when the RXSIF bit in the USARTn.STATUS register is set.
Value
Description
0
The Receiver Start Frame Interrupt is disabled
1
The Receiver Start Frame Interrupt is enabled
Bit 3 – LBME Loop-Back Mode Enable
This bit controls whether the Loop-back mode is enabled or not. When enabled, an internal connection between the
TXD pin and the USART receiver is created, and the input from the RXD pin to the USART receiver is disconnected.
Value
Description
0
Loop-back mode is disabled
1
Loop-back mode is enabled
Bit 2 – ABEIE Auto-Baud Error Interrupt Enable
This bit controls whether the Auto-baud Error Interrupt is enabled or not. When enabled, the interrupt will be triggered
when the ISFIF bit in the USARTn.STATUS register is set.
Value
Description
0
The Auto-Baud Error Interrupt is disabled
1
The Auto-Baud Error Interrupt is enabled
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Bits 1:0 – RS485[1:0] RS-485 Mode
This bit field enables the RS-485 and selects the operation mode. Writing RS485[0] to ‘1’ enables the RS-485 mode,
which automatically drives the XDIR pin high one clock cycle before starting transmission and pulls it low again when
the transmission is complete. Writing RS485[1] to ‘1’ enables the RS-485 mode, which automatically sets the TXD
pin to output one clock cycle before starting transmission and sets it back to input when the transmission is complete.
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24.5.7
Control B
Name:
Offset:
Reset:
Property:
Bit
7
RXEN
R/W
0
Access
Reset
CTRLB
0x06
0x00
-
6
TXEN
R/W
0
5
4
SFDEN
R/W
0
3
ODME
R/W
0
2
1
RXMODE[1:0]
R/W
R/W
0
0
0
MPCM
R/W
0
Bit 7 – RXEN Receiver Enable
This bit controls whether the USART receiver is enabled or not. Refer to 24.3.2.4.2 Disabling the Receiver for more
information.
Value
Description
0
The USART receiver is disabled
1
The USART receiver is enabled
Bit 6 – TXEN Transmitter Enable
This bit controls whether the USART transmitter is enabled or not. Refer to 24.3.2.3.1 Disabling the Transmitter for
more information.
Value
Description
0
The USART transmitter is disabled
1
The USART transmitter is enabled
Bit 4 – SFDEN Start-of-Frame Detection Enable
This bit controls whether the USART Start-of-Frame Detection mode is enabled or not. Refer to 24.3.4.2 Start-ofFrame Detection for more information.
Value
Description
0
The USART Start-of-Frame Detection mode is disabled
1
The USART Start-of-Frame Detection mode is enabled
Bit 3 – ODME Open Drain Mode Enable
This bit controls whether Open Drain mode is enabled or not. See the One-Wire Mode section for more information.
Value
Description
0
Open Drain mode is disabled
1
Open Drain mode is enabled
Bits 2:1 – RXMODE[1:0] Receiver Mode
Writing this bit field selects the receiver mode of the USART.
• Writing the bits to 0x00 enables Normal-Speed (NORMAL) mode. When the USART Communication Mode
(CMODE) bit field in the Control C (USARTn.CTRLC) register is configured to Asynchronous USART
(ASYNCHRONOUS) or Infrared Communication (IRCOM), always write the RXMODE bit field to 0x00.
•
•
•
Writing the bits to 0x01 enables Double-Speed (CLK2X) mode. Refer to 24.3.3.2.4 Double-Speed Operation for
more information.
Writing the bits to 0x02 enables Generic Auto-Baud (GENAUTO) mode. Refer to the Auto-Baud section for
more information.
Writing the bits to 0x03 enables Lin Constrained Auto-Baud (LINAUTO) mode. Refer to the Auto-Baud section
for more information.
Value
0x00
0x01
0x02
0x03
Name
NORMAL
CLK2X
GENAUTO
LINAUTO
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Description
Normal-Speed mode
Double-Speed mode
Generic Auto-Baud mode
LIN Constrained Auto-Baud mode
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Bit 0 – MPCM Multi-Processor Communication Mode
This bit controls whether the Multi-Processor Communication mode is enabled or not. Refer to 24.3.4.3
Multiprocessor Communication for more information.
Value
Description
0
Multi-Processor Communication mode is disabled
1
Multi-Processor Communication mode is enabled
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24.5.8
Control C - Normal Mode
Name:
Offset:
Reset:
Property:
CTRLC
0x07
0x03
-
This register description is valid for all modes except the Host SPI mode. When the USART Communication Mode
(CMODE) bit field in this register is written to ‘MSPI’, see CTRLC - Host SPI mode for the correct description.
Bit
Access
Reset
7
6
CMODE[1:0]
R/W
R/W
0
0
5
4
PMODE[1:0]
R/W
R/W
0
0
3
SBMODE
R/W
0
2
R/W
0
1
CHSIZE[2:0]
R/W
1
0
R/W
1
Bits 7:6 – CMODE[1:0] USART Communication Mode
This bit field selects the communication mode of the USART.
Writing a 0x03 to these bits alters the available bit fields in this register. See CTRLC - Host SPI mode.
Value
Name
Description
0x00
ASYNCHRONOUS
Asynchronous USART
0x01
SYNCHRONOUS
Synchronous USART
0x02
IRCOM
Infrared Communication
0x03
MSPI
Host SPI
Bits 5:4 – PMODE[1:0] Parity Mode
This bit field enables and selects the type of parity generation. See 24.3.4.1 Parity for more information.
Value
Name
Description
0x0
DISABLED
Disabled
0x1
Reserved
0x2
EVEN
Enabled, even parity
0x3
ODD
Enabled, odd parity
Bit 3 – SBMODE Stop Bit Mode
This bit selects the number of Stop bits to be inserted by the transmitter.
The receiver ignores this setting.
Value
Description
0
1 Stop bit
1
2 Stop bits
Bits 2:0 – CHSIZE[2:0] Character Size
This bit field selects the number of data bits in a frame. The receiver and transmitter use the same setting. For 9BIT
character size, the order of which byte to read or write first, low or high byte of RXDATA or TXDATA, can be
configured.
Value
Name
Description
0x00
5BIT
5-bit
0x01
6BIT
6-bit
0x02
7BIT
7-bit
0x03
8BIT
8-bit
0x04
Reserved
0x05
Reserved
0x06
9BITL
9-bit (Low byte first)
0x07
9BITH
9-bit (High byte first)
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24.5.9
Control C - Host SPI Mode
Name:
Offset:
Reset:
Property:
CTRLC
0x07
0x00
-
This register description is valid only when the USART is in Host SPI mode (CMODE written to MSPI). For other
CMODE values, see CTRLC - Normal Mode.
See 24.3.3.1.3 USART in Host SPI Mode for a full description of the Host SPI mode operation.
Bit
Access
Reset
7
6
CMODE[1:0]
R/W
R/W
0
0
5
4
3
2
UDORD
R/W
0
1
UCPHA
R/W
0
0
Bits 7:6 – CMODE[1:0] USART Communication Mode
This bit field selects the communication mode of the USART.
Writing a value different than 0x03 to these bits alters the available bit fields in this register. See CTRLC - Normal
Mode.
Value
Name
Description
0x00
ASYNCHRONOUS
Asynchronous USART
0x01
SYNCHRONOUS
Synchronous USART
0x02
IRCOM
Infrared Communication
0x03
MSPI
Host SPI
Bit 2 – UDORD USART Data Order
This bit controls the frame format. The receiver and transmitter use the same setting. Changing the setting of the
UDORD bit will corrupt all ongoing communication for both the receiver and the transmitter.
Value
Description
0
MSb of the data word is transmitted first
1
LSb of the data word is transmitted first
Bit 1 – UCPHA USART Clock Phase
This bit controls the phase of the interface clock. Refer to the Clock Generation section for more information.
Value
Description
0
Data are sampled on the leading (first) edge
1
Data are sampled on the trailing (last) edge
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24.5.10 Baud Register
Name:
Offset:
Reset:
Property:
BAUD
0x08
0x00
-
The USARTn.BAUDL and USARTn.BAUDH register pair represents the 16-bit value, USARTn.BAUD. The low byte
[7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Ongoing transmissions of the transmitter and receiver will be corrupted if the baud rate is changed. Writing to this
register will trigger an immediate update of the baud rate prescaler. For more information on how to set the baud rate,
see Table 24-1.
Bit
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
BAUD[15:8]
Access
Reset
Bit
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
BAUD[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – BAUD[15:8] USART Baud Rate High Byte
This bit field holds the MSB of the 16-bit Baud register.
Bits 7:0 – BAUD[7:0] USART Baud Rate Low Byte
This bit field holds the LSB of the 16-bit Baud register.
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24.5.11 Debug Control Register
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x0B
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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24.5.12 IrDA Control Register
Name:
Offset:
Reset:
Property:
Bit
7
EVCTRL
0x0C
0x00
-
6
5
4
3
Access
Reset
2
1
0
IREI
R/W
0
Bit 0 – IREI IrDA Event Input Enable
This bit controls whether the IrDA event input is enabled or not. See 24.3.3.2.7 IRCOM Mode of Operation for more
information.
Value
Description
0
IrDA Event input is enabled
1
IrDA Event input is disabled
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24.5.13 IRCOM Transmitter Pulse Length Control Register
Name:
Offset:
Reset:
Property:
Bit
7
TXPLCTRL
0x0D
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
TXPL[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TXPL[7:0] Transmitter Pulse Length
This 8-bit value sets the pulse modulation scheme for the transmitter. Setting this register will only have an effect if
IRCOM mode is selected by the USART, and it must be configured before the USART transmitter is enabled (TXEN).
Value
Description
0x00
3/16 of the baud rate period pulse modulation is used
0x01Fixed pulse length coding is used. The 8-bit value sets the number of peripheral clock periods for the
0xFE
pulse. The start of the pulse will be synchronized with the rising edge of the baud rate clock.
0xFF
Pulse coding disabled. RX and TX signals pass through the IRCOM module unaltered. This enables
other features through the IRCOM module, such as half-duplex USART, loop-back testing, and USART
RX input from an event channel.
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24.5.14 IRCOM Receiver Pulse Length Control Register
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RXPLCTRL
0x0E
0x00
-
6
5
4
R/W
0
R/W
0
R/W
0
3
RXPL[6:0]
R/W
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 6:0 – RXPL[6:0] Receiver Pulse Length
This 7-bit value sets the filter coefficient for the IRCOM transceiver. Setting this register will only have an effect if
IRCOM mode is selected by a USART, and it must be configured before the USART receiver is enabled (RXEN).
Value
Description
0x00
Filtering disabled
0x01Filtering enabled. The value of RXPL+1 represents the number of samples required for a received
0x7F
pulse to be accepted.
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SPI - Serial Peripheral Interface
25.
SPI - Serial Peripheral Interface
25.1
Features
•
•
•
•
•
•
•
•
25.2
Full Duplex, Three-Wire Synchronous Data Transfer
Host or Client Operation
LSb First or MSb First Data Transfer
Seven Programmable Bit Rates
End of Transmission Interrupt Flag
Write Collision Flag Protection
Wake-up from Idle Mode
Double-Speed (CK/2) Host SPI Mode
Overview
The Serial Peripheral Interface (SPI) is a high-speed synchronous data transfer interface using three or four pins. It
allows full-duplex communication between an AVR® device and peripheral devices or between several
microcontrollers. The SPI peripheral can be configured as either host or client. The host initiates and controls all data
transactions.
The interconnection between host and client devices with SPI is shown in the block diagram. The system consists of
two shift registers and a server clock generator. The SPI host initiates the communication cycle by pulling the desired
client’s Client Select (SS) signal low. The host and client prepare the data to be sent to their respective shift registers,
and the host generates the required clock pulses on the SCK line to exchange data. Data are always shifted from
host to client on the host output, client input (MOSI) line, and from client to host on the host input, client output
(MISO) line.
25.2.1
Block Diagram
Figure 25-1. SPI Block Diagram
CLIENT
HOST
DATA
DATA
Transmit Data
Buffer
Transmit Data
Buffer
Buffer
mode
Buffer
mode
LSb
MSb
MISO
MISO
MOSI
MOSI
8-bit Shift Register
LSb
MSb
8-bit Shift Register
SPI CLOCK
GENERATOR
SCK
SCK
SS
SS
Receive Data
Receive Data
Receive Data
Buffer
Receive Data
Buffer
Buffer
mode
Buffer
mode
DATA
DATA
The SPI is built around an 8-bit shift register that will shift data out and in at the same time. The Transmit Data
register and the Receive Data register are not physical registers but are mapped to other registers when written or
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SPI - Serial Peripheral Interface
read: Writing the Transmit Data (SPIn.DATA) register will write the shift register in Normal mode and the Transmit
Buffer register in Buffer mode. Reading the Receive Data (SPIn.DATA) register will read the Receive Data register in
Normal mode and the Receive Data Buffer in Buffer mode.
In Host mode, the SPI has a clock generator to generate the SCK clock. In Client mode, the received SCK clock is
synchronized and sampled to trigger the shifting of data in the shift register.
25.2.2
Signal Description
Table 25-1. Signals in Host and Client Mode
Signal
Pin Configuration
Description
Host Mode
defined(1)
Client Mode
MOSI
Host Out Client In
User
MISO
Host In Client Out
Input
SCK
Serial Clock
User defined(1)
Input
Client Select
defined(1)
Input
SS
User
Input
User defined(1,2)
Notes:
1. If the pin data direction is configured as output, the pin level is controlled by the SPI.
2. If the SPI is in Client mode and the MISO pin data direction is configured as output, the SS pin controls the
MISO pin output in the following way:
– If the SS pin is driven low, the MISO pin is controlled by the SPI
– If the SS pin is driven high, the MISO pin is tri-stated
When the SPI module is enabled, the pin data direction for the signals marked with “Input” in Table 25-1 is
overridden.
25.3
Functional Description
25.3.1
Initialization
Initialize the SPI to a basic functional state by following these steps:
1. Configure the SS pin in the port peripheral.
2. Select the SPI host/client operation by writing the Host/Client Select (MASTER) bit in the Control A
(SPIn.CTRLA) register.
3. In Host mode, select the clock speed by writing the Prescaler (PRESC) bits and the Clock Double (CLK2X) bit
in SPIn.CTRLA.
4. Optional: Select the Data Transfer mode by writing to the MODE bits in the Control B (SPIn.CTRLB) register.
5. Optional: Write the Data Order (DORD) bit in SPIn.CTRLA.
6. Optional: Set up the Buffer mode by writing the BUFEN and BUFWR bits in the Control B (SPIn.CTRLB)
register.
7. Optional: To disable the multi-host support in Host mode, write ‘1’ to the Client Select Disable (SSD) bit in
SPIn.CTRLB.
8. Enable the SPI by writing a ‘1’ to the ENABLE bit in SPIn.CTRLA.
25.3.2
Operation
25.3.2.1 Host Mode Operation
When the SPI is configured in Host mode, a write to the SPIn.DATA register will start a new transfer. The SPI host
can operate in two modes, Normal and Buffer, as explained below.
25.3.2.1.1 Normal Mode
In Normal mode, the system is single-buffered in the transmit direction and double-buffered in the receive direction.
This influences the data handling in the following ways:
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SPI - Serial Peripheral Interface
1.
New bytes to be sent cannot be written to the DATA (SPIn.DATA) register before the entire transfer has been
completed. A premature write will cause corruption of the transmitted data, and the Write Collision (WRCOL)
flag in SPIn.INTFLAGS will be set.
Received bytes are written to the Receive Data Buffer register immediately after the transmission is
completed.
The Receive Data Buffer register has to be read before the next transmission is completed, or the data will be
lost. This register is read by reading SPIn.DATA.
The Transmit Data Buffer and Receive Data Buffer registers are not used in Normal mode.
2.
3.
4.
After a transfer has been completed, the Interrupt Flag (IF) will be set in the Interrupt Flags (SPIn.INTFLAGS)
register. This will cause the corresponding interrupt to be executed if this interrupt and the global interrupts are
enabled. Setting the Interrupt Enable (IE) bit in the Interrupt Control (SPIn.INTCTRL) register will enable the interrupt.
25.3.2.1.2 Buffer Mode
The Buffer mode is enabled by writing the BUFEN bit in the SPIn.CTRLB register to ‘1’. The BUFWR bit in
SPIn.CTRLB does not affect Host mode. In Buffer mode, the system is double-buffered in the transmit direction and
triple-buffered in the receive direction. This influences the data handling in the following ways:
1. New bytes can be written to the DATA (SPIn.DATA) register as long as the Data Register Empty Interrupt Flag
(DREIF) in the Interrupt Flag (SPIn.INTFLAGS) register is set. The first write will be transmitted right away, and
the following write will go to the Transmit Data Buffer register.
2. A received byte is placed in a two-entry Receive First-In, First-Out (RX FIFO) queue comprised of the Receive
Data register and Receive Data Buffer immediately after the transmission is completed.
3. The DATA register is used to read from the RX FIFO. The RX FIFO must be read at least every second
transfer to avoid any loss of data.
When both the shift register and the Transmit Data Buffer register become empty, the Transfer Complete Interrupt
Flag (TXCIF) in the Interrupt Flags (SPIn.INTFLAGS) register will be set. This will cause the corresponding interrupt
to be executed if this interrupt and the global interrupts are enabled. Setting the Transfer Complete Interrupt Enable
(TXCIE) in the Interrupt Control (SPIn.INTCTRL) register enables the Transfer Complete Interrupt.
25.3.2.1.3 SS Pin Functionality in Host Mode - Multi-Host Support
In Host mode, the Client Select Disable (SSD) bit in the Control B (SPIn.CTRLB) register controls how the SPI uses
the SS pin.
•
•
•
If SSD in SPIn.CTRLB is ‘0’, the SPI can use the SS pin to transition from Host to Client mode. This allows
multiple SPI hosts on the same SPI bus.
If SSD in SPIn.CTRLB is ‘0’, and the SS pin is configured as an output pin, it can be used as a regular I/O pin or
by other peripheral modules and will not affect the SPI system
If SSD in SPIn.CTRLB is ‘1’, the SPI does not use the SS pin. It can be used as a regular I/O pin or by other
peripheral modules.
If the SSD bit in SPIn.CTRLB is ‘0’, and the SS is configured as an input pin, the SS pin must be held high to ensure
Host SPI operation. A low level will be interpreted as another Host is trying to take control of the bus. This will switch
the SPI into Client mode, and the hardware of the SPI will perform the following actions:
1. The Host (MASTER) bit in the SPI Control A (SPIn.CTRLA) register is cleared, and the SPI system becomes a
client. The direction of the SPI pins will be switched when the conditions in Table 25-2 are met.
2. The Interrupt Flag (IF) bit in the Interrupt Flags (SPIn.INTFLAGS) register will be set. If the interrupt is enabled
and the global interrupts are enabled, the interrupt routine will be executed.
Table 25-2. Overview of the SS Pin Functionality when the SSD Bit in SPIn.CTRLB is ‘0’
SS Configuration
Input
Output
© 2020 Microchip Technology Inc.
SS Pin-Level
Description
High
Host activated (selected)
Low
Host deactivated, switched to Client
mode
High
Host activated (selected)
Low
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Note: If the device is in Host mode and it cannot be ensured that the SS pin will stay high between two
transmissions, the status of the Host (MASTER) bit in SPIn.CTRLA has to be checked before a new byte is written.
After the Host bit has been cleared by a low level on the SS line, it must be set by the application to re-enable the SPI
Host mode.
25.3.2.2 Client Mode
In Client mode, the SPI peripheral receives SPI clock and Client Select from a Host. Client mode supports three
operational modes: One Normal mode and two configurations for the Buffered mode. In Client mode, the control logic
will sample the incoming signal on the SCK pin. To ensure correct sampling of this clock signal, the minimum low and
high periods must each be longer than two peripheral clock cycles.
25.3.2.2.1 Normal Mode
In Normal mode, the SPI peripheral will remain Idle as long as the SS pin is driven high. In this state, the software
may update the contents of the DATA register, but the data will not be shifted out by incoming clock pulses on the
SCK pin until the SS pin is driven low. If the SS pin is driven low, the client will start to shift out data on the first SCK
clock pulse. When one byte has been completely shifted, the SPI Interrupt Flag (IF) in SPIn.INTFLAGS is set.
The user application may continue placing new data to be sent into the DATA register before reading the incoming
data. New bytes to be sent cannot be written to the DATA register before the entire transfer has been completed. A
premature write will be ignored, and the hardware will set the Write Collision (WRCOL) flag in SPIn.INTFLAGS.
When the SS pin is driven high, the SPI logic is halted, and the SPI client will not receive any new data. Any partially
received packet in the shift register will be lost.
Figure 25-2 shows a transmission sequence in Normal mode. Notice how the value 0x45 is written to the DATA
register but never transmitted.
Figure 25-2. SPI Timing Diagram in Normal Mode (Buffer Mode Not Enabled)
SS
SCK
Write DATA
Write value
0x43
0x44
0x45
0x46
WRCOL
IF
Shift Register
Data sent
0x43
0x43
0x44
0x44
0x46
0x46
The figure above shows three transfers and one write to the DATA register while the SPI is busy with a transfer. This
write will be ignored, and the Write Collision (WRCOL) flag in SPIn.INTFLAGS is set.
25.3.2.2.2 Buffer Mode
To avoid data collisions, the SPI peripheral can be configured in Buffered mode by writing a ‘1’ to the Buffer Mode
Enable (BUFEN) bit in the Control B (SPIn.CTRLB) register. In this mode, the SPI has additional interrupt flags and
extra buffers. The extra buffers are shown in Figure 25-1. There are two different modes for the Buffer mode,
selected with the Buffer mode Wait for Receive (BUFWR) bit. The two different modes are described below with
timing diagrams.
Client Buffer Mode with Wait for Receive Bit Written to ‘0’
In Client mode, if the Buffer mode Wait for Receive (BUFWR) bit in SPIn.CTRLB is written to ‘0’, a dummy byte will
be sent before the transmission of user data starts. Figure 25-3 shows a transmission sequence with this
configuration. Notice how the value 0x45 is written to the Data (SPIn.DATA) register but never transmitted.
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Figure 25-3. SPI Timing Diagram in Buffer Mode with BUFWR in SPIn.CTRLB Written to ‘0’
SS
SCK
Write DATA
Write value
0x43
0x44
0x45
0x46
DREIF
TXCIF
RXCIF
Transmit Buffer
Shift Register
Data sent
0x43
Dummy
Dummy
0x46
0x44
0x44
0x43
0x43
0x44
0x46
0x46
When the Wait for Receive (BUFWR) bit in SPIn.CTRLB is written to ‘0’, all writes to the Data (SPIn.DATA) register
go to the Transmit Data Buffer register. The figure above shows that the value 0x43 is written to the Data
(SPIn.DATA) register but not immediately transferred to the shift register, so the first byte sent will be a dummy byte.
The value of the dummy byte equals the values that were in the shift register at the same time. After the first dummy
transfer is completed, the value 0x43 is transferred to the shift register. Then 0x44 is written to the Data (SPIn.DATA)
register and goes to the Transmit Data Buffer register. A new transfer is started, and 0x43 will be sent. The value
0x45 is written to the Data (SPIn.DATA) register, but the Transmit Data Buffer register is not updated since it is
already full containing 0x44 and the Data Register Empty Interrupt Flag (DREIF) in SPIn.INTFLAGS is low. The value
0x45 will be lost. After the transfer, the value 0x44 is moved to the shift register. During the next transfer, 0x46 is
written to the Data (SPIn.DATA) register, and 0x44 is sent out. After the transfer is complete, 0x46 is copied into the
shift register and sent out in the next transfer.
The DREIF goes low every time the Transmit Data Buffer register is written and goes high after a transfer when the
previous value in the Transmit Data Buffer register is copied into the shift register. The Receive Complete Interrupt
Flag (RXCIF) in SPIn.INTFLAGS is set one cycle after the DREIF goes high. The Transfer Complete Interrupt Flag is
set one cycle after the Receive Complete Interrupt Flag is set when both the value in the shift register and in the
Transmit Data Buffer register has been sent.
Client Buffer Mode with Wait for Receive Bit Written to ‘1’
In Client mode, if the Buffer mode Wait for Receive (BUFWR) bit in SPIn.CRTLB is written to ‘1’, the transmission of
user data starts as soon as the SS pin is driven low. Figure 25-4 shows a transmission sequence with this
configuration. Notice how the value 0x45 is written to the Data (SPIn.DATA) register but never transmitted.
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Figure 25-4. SPI Timing Diagram in Buffer Mode with CTRLB.BUFWR Written to ‘1’
SS
SCK
Write DATA
Write value
0x43
0x44
0x45
0x46
DREIF
TXCIF
RXCIF
Transmit Buffer
Shift Register
0x46
0x44
0x43
0x43
Data sent
0x46
0x44
0x43
0x44
0x46
All writes to the Data (SPIn.DATA) register go to the Transmit Data Buffer register. The figure above shows that the
value 0x43 is written to the Data (SPIn.DATA) register, and since the SS pin is high, it is copied to the shift register in
the next cycle. The next write (0x44) will go to the Transmit Data Buffer register. During the first transfer, the value
0x43 will be shifted out. In the figure above, the value 0x45 is written to the Data (SPIn.DATA) register, but the
Transmit Data Buffer register is not updated since the DREIF is low. After the transfer is completed, the value 0x44
from the Transmit Data Buffer register is copied to the shift register. The value 0x46 is written to the Transmit Data
Buffer register. During the next two transfers, 0x44 and 0x46 are shifted out. The flags behave identically to the Buffer
Mode Wait for Receive (BUFWR) bit in SPIn.CTRLB set to ‘0’.
25.3.2.2.3 SS Pin Functionality in Client Mode
The Client Select (SS) pin plays a central role in the operation of the SPI. Depending on the SPI mode and the
configuration of this pin, it can be used to activate or deactivate devices. The SS pin is used as a Chip Select pin.
In Client mode, the SS, MOSI, and SCK are always inputs. The behavior of the MISO pin depends on the configured
data direction of the pin in the port peripheral and the value of SS. When the SS pin is driven low, the SPI is activated
and will respond to received SCK pulses by clocking data out on MISO if the user has configured the data direction of
the MISO pin as an output. When the SS pin is driven high, the SPI is deactivated, meaning that it will not receive
incoming data. If the MISO pin data direction is configured as an output, the MISO pin will be tri-stated. Table 25-3
shows an overview of the SS pin functionality.
Table 25-3. Overview of the SS Pin Functionality
MISO Pin Mode
SS Configuration
SS Pin-Level
Description
Port Direction =
Output
Port Direction =
Input
High
Client deactivated
(deselected)
Tri-stated
Input
Low
Client activated
(selected)
Output
Input
Always Input
Note: In Client mode, the SPI state machine will be reset when the SS pin is driven high. If the SS pin is driven high
during a transmission, the SPI will stop sending and receiving data immediately and both data received and data sent
must be considered lost. As the SS pin is used to signal the start and end of a transfer, it is useful for achieving
packet/byte synchronization and keeping the Client bit counter synchronized with the host clock generator.
25.3.2.3 Data Modes
There are four combinations of SCK phase and polarity concerning the serial data. The desired combination is
selected by writing to the MODE bits in the Control B (SPIn.CTRLB) register.
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The SPI data transfer formats are shown below. Data bits are shifted out and latched in on opposite edges of the
SCK signal, ensuring sufficient time for data signals to stabilize.
The leading edge is the first clock edge of a clock cycle. The trailing edge is the last clock edge of a clock cycle.
Figure 25-5. SPI Data Transfer Modes
1
2
3
4
5
6
7
8
MISO
1
2
3
4
5
6
7
8
MOSI
1
2
3
4
5
6
7
8
SPI Mode 0
Cycle #
SS
SCK
Sampling
SPI Mode 1
Cycle #
1
2
3
4
5
6
7
8
MISO
1
2
3
4
5
6
7
8
MOSI
1
2
3
4
5
6
7
8
SS
SCK
Sampling
SPI Mode 2
Cycle #
1
2
3
4
5
6
7
8
MISO
1
2
3
4
5
6
7
8
MOSI
1
2
3
4
5
6
7
8
SS
SCK
Sampling
SPI Mode 3
Cycle #
1
2
3
4
5
6
7
8
MISO
1
2
3
4
5
6
7
8
MOSI
1
2
3
4
5
6
7
8
SS
SCK
Sampling
25.3.2.4 Events
The SPI can generate the following events:
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SPI - Serial Peripheral Interface
Table 25-4. Event Generators in SPI
Generator Name
Module
Event
SPIn
SCK
Description
Event Type
SPI Host clock
Level
Generating
Clock
Domain
CLK_PER
Length of Event
Minimum two CLK_PER periods
The SPI has no event users.
Refer to the Event System section for more details regarding event types and Event System configuration.
25.3.2.5 Interrupts
Table 25-5. Available Interrupt Vectors and Sources
Name
SPIn
Conditions
Vector Description
SPI interrupt
Normal Mode
•
•
IF: Interrupt Flag interrupt
WRCOL: Write Collision interrupt
Buffer Mode
•
•
•
•
SSI: Client Select Trigger Interrupt
DRE: Data Register Empty interrupt
TXC: Transfer Complete interrupt
RXC: Receive Complete interrupt
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
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25.4
Register Summary
Offset
Name
Bit Pos.
7
6
5
4
0x00
0x01
0x02
0x03
0x03
0x04
CTRLA
CTRLB
INTCTRL
INTFLAGS
INTFLAGS
DATA
7:0
7:0
7:0
7:0
7:0
7:0
DORD
BUFWR
TXCIE
WRCOL
TXCIF
MASTER
CLK2X
BUFEN
RXCIE
IF
RXCIF
DREIE
SSIE
DREIF
SSIF
DATA[7:0]
25.5
3
2
1
PRESC[1:0]
SSD
0
ENABLE
MODE[1:0]
IE
BUFOVF
Register Description
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25.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLA
0x00
0x00
-
6
DORD
R/W
0
5
MASTER
R/W
0
4
CLK2X
R/W
0
3
2
1
PRESC[1:0]
R/W
R/W
0
0
0
ENABLE
R/W
0
Bit 6 – DORD Data Order
Value
Description
0
The MSb of the data word is transmitted first
1
The LSb of the data word is transmitted first
Bit 5 – MASTER Host/Client Select
This bit selects the desired SPI mode.
If SS is configured as input and driven low while this bit is ‘1’, then this bit is cleared, and the IF in SPIn.INTFLAGS is
set. The user has to write MASTER = 1 again to re-enable SPI Host mode.
This behavior is controlled by the Client Select Disable (SSD) bit in SPIn.CTRLB.
Value
Description
0
SPI Client mode selected
1
SPI Host mode selected
Bit 4 – CLK2X Clock Double
When this bit is written to ‘1’, the SPI speed (SCK frequency, after internal prescaler) is doubled in Host mode.
Value
Description
0
SPI speed (SCK frequency) is not doubled
1
SPI speed (SCK frequency) is doubled in Host mode
Bits 2:1 – PRESC[1:0] Prescaler
This bit field controls the SPI clock rate configured in Host mode. These bits have no effect in Client mode. The
relationship between SCK and the peripheral clock frequency (fCLK_PER) is shown below.
The output of the SPI prescaler can be doubled by writing the CLK2X bit to ‘1’.
Value
Name
Description
0x0
DIV4
CLK_PER/4
0x1
DIV16
CLK_PER/16
0x2
DIV64
CLK_PER/64
0x3
DIV128
CLK_PER/128
Bit 0 – ENABLE SPI Enable
Value
Description
0
SPI is disabled
1
SPI is enabled
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25.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
BUFEN
R/W
0
CTRLB
0x01
0x00
-
6
BUFWR
R/W
0
5
4
3
2
SSD
R/W
0
1
0
MODE[1:0]
R/W
0
R/W
0
Bit 7 – BUFEN Buffer Mode Enable
Writing this bit to ‘1’ enables Buffer mode. This will enable two receive buffers and one transmit buffer. Both will have
separate interrupt flags, transmit complete and receive complete.
Bit 6 – BUFWR Buffer Mode Wait for Receive
When writing this bit to ‘0’, the first data transferred will be a dummy sample.
Value
Description
0
One SPI transfer must be completed before the data are copied into the shift register
1
If writing to the Data register when the SPI is enabled and SS is high, the first write will go directly to
the shift register
Bit 2 – SSD Client Select Disable
If this bit is set when operating as SPI Host (MASTER = 1 in SPIn.CTRLA), SS does not disable Host mode.
Value
Description
0
Enable the Client Select line when operating as SPI host
1
Disable the Client Select line when operating as SPI host
Bits 1:0 – MODE[1:0] Mode
These bits select the Transfer mode. The four combinations of SCK phase and polarity concerning the serial data are
shown below. These bits decide whether the first edge of a clock cycle (leading edge) is rising or falling and whether
data setup and sample occur on the leading or trailing edge. When the leading edge is rising, the SCK signal is low
when idle, and when the leading edge is falling, the SCK signal is high when idle.
Value
Name
Description
0x0
0
Leading edge: Rising, sample
Trailing edge: Falling, setup
0x1
1
Leading edge: Rising, setup
Trailing edge: Falling, sample
0x2
2
Leading edge: Falling, sample
Trailing edge: Rising, setup
0x3
3
Leading edge: Falling, setup
Trailing edge: Rising, sample
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25.5.3
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RXCIE
R/W
0
INTCTRL
0x02
0x00
-
6
TXCIE
R/W
0
5
DREIE
R/W
0
4
SSIE
R/W
0
3
2
1
0
IE
R/W
0
Bit 7 – RXCIE Receive Complete Interrupt Enable
In Buffer mode, this bit enables the Receive Complete interrupt. The enabled interrupt will be triggered when the
RXCIF in the SPIn.INTFLAGS register is set. In the Non-Buffer mode, this bit is ‘0’.
Bit 6 – TXCIE Transfer Complete Interrupt Enable
In Buffer mode, this bit enables the Transfer Complete interrupt. The enabled interrupt will be triggered when the
TXCIF in the SPIn.INTFLAGS register is set. In the Non-Buffer mode, this bit is ‘0’.
Bit 5 – DREIE Data Register Empty Interrupt Enable
In Buffer mode, this bit enables the Data Register Empty interrupt. The enabled interrupt will be triggered when the
DREIF in the SPIn.INTFLAGS register is set. In the Non-Buffer mode, this bit is ‘0’.
Bit 4 – SSIE Client Select Trigger Interrupt Enable
In Buffer mode, this bit enables the Client Select interrupt. The enabled interrupt will be triggered when the SSIF in
the SPIn.INTFLAGS register is set. In the Non-Buffer mode, this bit is ‘0’.
Bit 0 – IE Interrupt Enable
This bit enables the SPI interrupt when the SPI is not in Buffer mode. The enabled interrupt will be triggered when
RXCIF/IF is set in the SPIn.INTFLAGS register.
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25.5.4
Interrupt Flags - Normal Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
IF
R/W
0
INTFLAGS
0x03
0x00
-
6
WRCOL
R/W
0
5
4
3
2
1
0
Bit 7 – IF Interrupt Flag
This flag is set when a serial transfer is complete, and one byte is completely shifted in/out of the SPIn.DATA register.
If SS is configured as input and is driven low when the SPI is in Host mode, this will also set this flag. The IF is
cleared by hardware when executing the corresponding interrupt vector. Alternatively, the IF can be cleared by first
reading the SPIn.INTFLAGS register when IF is set and then accessing the SPIn.DATA register.
Bit 6 – WRCOL Write Collision
The WRCOL flag is set if the SPIn.DATA register is written before a complete byte has been shifted out. This flag is
cleared by first reading the SPIn.INTFLAGS register when WRCOL is set and then accessing the SPIn.DATA register.
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25.5.5
Interrupt Flags - Buffer Mode
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RXCIF
R/W
0
INTFLAGS
0x03
0x00
-
6
TXCIF
R/W
0
5
DREIF
R/W
0
4
SSIF
R/W
0
3
2
1
0
BUFOVF
R/W
0
Bit 7 – RXCIF Receive Complete Interrupt Flag
This flag is set when there are unread data in the Receive Data Buffer register and cleared when the Receive Data
Buffer register is empty (that is, it does not contain any unread data).
When interrupt-driven data reception is used, the Receive Complete Interrupt routine must read the received data
from the DATA register to clear RXCIF. If not, a new interrupt will occur directly after the return from the current
interrupt. This flag can also be cleared by writing a ‘1’ to its bit location.
Bit 6 – TXCIF Transfer Complete Interrupt Flag
This flag is set when all the data in the Transmit shift register has been shifted out, and there is no new data in the
transmit buffer (SPIn.DATA). The flag is cleared by writing a ‘1’ to its bit location.
Bit 5 – DREIF Data Register Empty Interrupt Flag
This flag indicates whether the Transmit Data Buffer register is ready to receive new data. The flag is ‘1’ when the
transmit buffer is empty and ‘0’ when the transmit buffer contains data to be transmitted that has not yet been moved
into the shift register. The DREIF is cleared after a Reset to indicate that the transmitter is ready.
The DREIF is cleared by writing to DATA. When interrupt-driven data transmission is used, the Data Register Empty
Interrupt routine must either write new data to DATA to clear DREIF or disable the Data Register Empty interrupt. If
not, a new interrupt will occur directly after the return from the current interrupt.
Bit 4 – SSIF Client Select Trigger Interrupt Flag
This flag indicates that the SPI has been in Host mode, and the SS pin has been pulled low externally, so the SPI is
now working in Client mode. The flag will only be set if the Client Select Disable (SSD) bit is not ‘1’. The flag is
cleared by writing a ‘1’ to its bit location.
Bit 0 – BUFOVF Buffer Overflow
This flag indicates data loss due to a Receive Data Buffer full condition. This flag is set if a Buffer Overflow condition
is detected. A Buffer Overflow occurs when the receive buffer is full (two bytes), and a third byte has been received in
the shift register. If there is no transmit data, the Buffer Overflow will not be set before the start of a new serial
transfer. This flag is cleared when the DATA register is read or by writing a ‘1’ to its bit location.
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25.5.6
Data
Name:
Offset:
Reset:
Property:
Bit
7
DATA
0x04
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DATA[7:0] SPI Data
The DATA register is used for sending and receiving data. Writing to the register initiates the data transmission when
in Host mode while preparing data for sending in Client mode. The byte written to the register shifts out on the SPI
output line when a transaction is initiated.
The SPIn.DATA register is not a physical register. Depending on what mode is configured, it is mapped to other
registers, as described below.
• Normal mode:
– Writing the DATA register will write the shift register
– Reading from DATA will read from the Receive Data register
• Buffer mode:
– Writing the DATA register will write to the Transmit Data Buffer register
– Reading from DATA will read from the Receive Data Buffer register. The contents of the Receive Data
register will then be moved to the Receive Data Buffer register.
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TWI - Two-Wire Interface
26.
TWI - Two-Wire Interface
26.1
Features
•
•
•
•
•
•
•
26.2
Two-Wire Communication Interface
Philips I2C Compatible
– Standard mode
– Fast mode
– Fast mode Plus
System Management Bus (SMBus) 2.0 Compatible
– Support arbitration between Start/repeated Start and data bit
– Client arbitration allows support for the Address Resolution Protocol (ARP) in software
– Configurable SMBus Layer 1 time-outs in hardware
Independent Host and Client Operation
– Combined (same pins)
– Single or multi-host bus operation with full arbitration support
Hardware Support for Client Address Match
– Operates in all sleep modes
– 7-bit address recognition
– General Call Address recognition
– Support for address range masking or secondary address match
Input Filter for Bus Noise Suppression
Smart Mode Support
Overview
The Two-Wire Interface (TWI) is a bidirectional, two-wire communication interface (bus) with a Serial Data Line (SDA)
and a Serial Clock Line (SCL).
The TWI bus connects one or several client devices to one or several host devices. Any device connected to the bus
can act as a host, a client, or both. The host generates the SCL by using a Baud Rate Generator (BRG) and initiates
data transactions by addressing one client and telling whether it wants to transmit or receive data. The BRG is
capable of generating the Standard mode (Sm) and Fast mode (Fm, Fm+) bus frequencies from 100 kHz up to 1
MHz.
The TWI will detect Start and Stop conditions, bus collisions, and bus errors. Arbitration lost, errors, collision, and
clock hold are also detected and indicated in separate status flags available in both Host and Client modes.
The TWI supports multi-host bus operation and arbitration. An arbitration scheme handles the case where more than
one host tries to transmit data at the same time. The TWI also supports Smart mode, which can auto-trigger
operations and thus reduce software complexity. The TWI supports Quick Command mode where the host can
address a client without exchanging data.
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TWI - Two-Wire Interface
26.2.1
Block Diagram
Figure 26-1. TWI Block Diagram
Host
BAUD
TxDATA
0
Baud Rate Generator
Client
TxDATA
SCL
SCL Hold Low
0
SCL Hold Low
shift register
shift register
0
SDA
0
RxDATA
26.2.2
ADDR/ADDRMASK
RxDATA
==
Signal Description
Signal
Description
Type
SCL
Serial Clock Line
Digital I/O
SDA
Serial Data Line
Digital I/O
26.3
Functional Description
26.3.1
General TWI Bus Concepts
The TWI provides a simple, bidirectional, two-wire communication bus consisting of:
• Serial Data Line (SDA) for packet transfer
• Serial Clock Line (SCL) for the bus clock
The two lines are open-collector lines (wired-AND).
The TWI bus topology is a simple and efficient method of interconnecting multiple devices on a serial bus. A device
connected to the bus can be a host or a client. Only host devices can control the bus and the bus communication.
A unique address is assigned to each client device connected to the bus, and the host will use it to control the client
and initiate a transaction. Several hosts can be connected to the same bus. This is called a multi-host environment.
An arbitration mechanism is provided for resolving bus ownership among hosts since only one host device may own
the bus at any given time.
A host indicates the start of a transaction by issuing a Start condition (S) on the bus. The host provides the clock
signal for the transaction. An address packet with a 7-bit client address (ADDRESS) and a direction bit, representing
whether the host wishes to read or write data (R/W), are then sent.
The addressed I2C client will then acknowledge (ACK) the address, and data packet transactions can begin. Every 9bit data packet consists of eight data bits followed by a 1-bit reply indicating whether the data was acknowledged or
not by the receiver.
After all the data packets (DATA) are transferred, the host issues a Stop condition (P) on the bus to end the
transaction.
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Figure 26-2. Basic TWI Transaction Diagram Topology for a 7-bit Address Bus
SDA
SCL
6 ... 0
S
7 ... 0
ADDRESS
S
ADDRESS
R/W
R/W
ACK
7 ... 0
DATA
ACK
DATA
A
A
DATA
P
ACK/NACK
DATA
A/A
P
Direction
Address Packet
Data Packet #0
Data Packet #1
Transaction
Bus Driver
Host driving bus
S
START condition
Client driving bus
Sr
repeated START condition
Either Host or Client driving bus
P
STOP condition
Data Package Direction
R
Host Read
W
Acknowledge
A
Acknowledge (ACK)
'0'
'1'
Host Write
'0'
26.3.2
Special Bus Conditions
A
Not Acknowledge (NACK)
'1'
TWI Basic Operation
26.3.2.1 Initialization
If used, the following bits must be configured before enabling the TWI device:
• The SDA Hold Time (SDAHOLD) bit field from the Control A (TWIn.CTRLA) register
• The FM Plus Enable (FMPEN) bit from the Control A (TWIn.CTRLA) register
26.3.2.1.1 Host Initialization
Write the Host Baud Rate (TWIn.MBAUD) register to a value that will result in a valid TWI bus clock frequency.
Writing a ‘1’ to the Enable TWI Host (ENABLE) bit in the Host Control A (TWIn.MCTRLA) register will enable the TWI
host. The Bus State (BUSSTATE) bit field from the Host Status (TWIn.MSTATUS) register must be set to 0x1 to force
the bus state to Idle.
26.3.2.1.2 Client Initialization
Follow these steps to initialize the client:
1.
2.
3.
Before enabling the TWI device, configure the SDA Setup Time (SDASETUP) bit from the Control A
(TWIn.CTRLA) register.
Write the address of the client to the Client Address (TWIn.SADDR) register.
Write a ‘1’ to the Enable TWI Client (ENABLE) bit in the Client Control A (TWIn.SCTRLA) register to enable
the TWI client.
The client device will now wait for a host device to issue a Start condition and the matching client address.
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TWI - Two-Wire Interface
26.3.2.2 TWI Host Operation
The TWI host is byte-oriented, with an optional interrupt after each byte. There are separate interrupt flags for the
host write and read operation. Interrupt flags can also be used for polled operation. There are dedicated status flags
for indicating ACK/NACK received, bus error, arbitration lost, clock hold, and bus state.
When an interrupt flag is set to ‘1’, the SCL is forced low. This will give the host time to respond or handle any data
and will, in most cases, require software interaction. Clearing the interrupt flags releases the SCL. The number of
interrupts generated is kept to a minimum by automatic handling of most conditions.
26.3.2.2.1 Clock Generation
The TWI supports several transmission modes with different frequency limitations:
• Standard mode (Sm) up to 100 kHz
• Fast mode (Fm) up to 400 kHz
• Fast mode Plus (Fm+) up to 1 MHz
Write the Host Baud Rate (TWIn.MBAUD) register to a value that will result in a TWI bus clock frequency equal to, or
less than, those frequency limits, depending on the transmission mode.
The low (tLOW) and high (tHIGH) times are determined by the Host Baud Rate (TWIn.MBAUD) register, while the rise
(tR) and fall (tOF) times are determined by the bus topology.
Figure 26-3. SCL Timing
SCL
tHD;STA
tSU;STA
tLOW
tHIGH
tOF
tSP
tHD;DAT
tSU;DAT
tR
tBUF
tSU;STO
SDA
S
•
•
•
•
P
S
tLOW is the low period of SCL clock
tHIGH is the high period of SCL clock
tR is determined by the bus impedance; for internal pull-ups. Refer to the Electrical Characteristics section for
details.
tOF is the output fall time and is determined by the open-drain current limit and bus impedance. Refer to the
Electrical Characteristics section for details.
Properties of the SCL Clock
The SCL frequency is given by:
Equation 26-1. SCL Frequency
�SCL =
1
[Hz]
�LOW + �HIGH + �OF + �R
The SCL clock is designed to have a 50/50 duty cycle, where the low period of the duty cycle comprises of tOF and
tLOW. tHIGH will not start until a high state of SCL has been detected. The BAUD bit field in the TWIn.MBAUD register
and the SCL frequency are related by the following formula:
Equation 26-2. SCL Frequency
���� =
����_���
10 + 2 × ���� + ����_��� × ��
Equation 26-2 can be transformed to express BAUD:
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TWI - Two-Wire Interface
Equation 26-3. BAUD
���� =
����_���
����_��� × ��
− 5+
2 × ����
2
Calculation of the BAUD Value
To ensure operation within the specifications of the desired speed mode (Sm, Fm, Fm+), follow these steps:
1. Calculate a value for the BAUD bit field using Equation 26-3.
2. Calculate tLOW using the BAUD value from step 1:
3.
Equation 26-4. tLOW
���� + 5
− ���
���� =
����_���
Check if tLOW from Equation 26-4 is above the specified minimum of the desired mode (tLOW_Sm = 4700 ns,
tLOW_Fm = 1300 ns, tLOW_Fm+ = 500 ns).
– If the calculated tLOW is above the limit, use the BAUD value from Equation 26-3
– If the limit is not met, calculate a new BAUD value using Equation 26-5 below, where tLOW_mode is either
tLOW_Sm, tLOW_Fm, or tLOW_Fm+ from the mode specifications:
Equation 26-5. BAUD
���� = ����_��� × (����_���� + ���) − 5
26.3.2.2.2 TWI Bus State Logic
The bus state logic continuously monitors the activity on the TWI bus when the host is enabled. It continues to
operate in all sleep modes, including Power-Down.
The bus state logic includes Start and Stop condition detectors, collision detection, inactive bus time-out detection,
and a bit counter. These are used to determine the bus state. The software can get the current bus state by reading
the Bus State (BUSSTATE) bit field in the Host Status (TWIn.MSTATUS) register.
The bus state can be Unknown, Idle, Busy or Owner, and it is determined according to the state diagram shown
below.
Figure 26-4. Bus State Diagram
RESET
UNKNOWN
(0b00)
Time-out or Stop Condition
External Start Condition
IDLE
(0b01)
Time-out or Stop Condition
BUSY
(0b11)
Write ADDR to generate
Start Condition
OWNER
(0b10)
Lost Arbitration
External Repeated
Start Condition
Stop Condition
Write ADDR to generate
Repeated Start Condition
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1.
2.
3.
4.
Unknown: The bus state machine is active when the TWI host is enabled. After the TWI host has been
enabled, the bus state is Unknown. The bus state will also be set to Unknown after a system Reset is
performed or after the TWI host is disabled.
Idle: The bus state machine can be forced to enter the Idle state by writing 0x1 to the Bus State (BUSSTATE)
bit field. The bus state logic cannot be forced into any other state. If no state is set by the application software,
the bus state will become Idle when the first Stop condition is detected. If the Inactive Bus Time-Out
(TIMEOUT) bit field from the Host Control A (TWIn.MCTRLA) register is configured to a nonzero value, the
bus state will change to Idle on the occurrence of a time-out. When the bus is Idle, it is ready for a new
transaction.
Busy: If a Start condition, generated externally, is detected when the bus is Idle, the bus state becomes Busy.
The bus state changes back to Idle when a Stop condition is detected or when a time-out, if configured, is set.
Owner: If a Start condition is generated internally when the bus is Idle, the bus state becomes Owner. If the
complete transaction is performed without interference, the host issues a Stop condition, and the bus state
changes back to Idle. If a collision is detected, the arbitration is lost, and the bus state becomes Busy until a
Stop condition is detected.
26.3.2.2.3 Transmitting Address Packets
The host starts performing a bus transaction when the Host Address (TWIn.MADDR) register is written with the client
address and the R/W direction bit. The value of the MADDR register is then copied into the Host Data (TWIn.MDATA)
register. If the bus state is Busy, the TWI host will wait until the bus state becomes Idle before issuing the Start
condition. The TWI will issue a Start condition, and the shift register performs a byte transmit operation on the bus.
Depending on the arbitration and the R/W direction bit, one of four cases (M1 to M4) arises after the transmission of
the address packet.
Figure 26-5. TWI Host Operation
M4
HOST DATA INTERRUPT
P
P
A
Sr
BUSY
P
IDLE
S
ADDRESS
W
OWNER
M3
A
Sr
A
IF
M1
DATA
Sr
A
M4
M4
IF
A
The host provides data
on the bus
Mn
P
P
R
BUSY
BUSY
Interrupt flag raised
Addressed client provides
data on the bus
BUSY
OWNER
M3
A
Sr
A
DATA
IF
M2
Sr
A
Diagram cases
Case M1: Address Packet Transmit Complete - Direction Bit Set to ‘0’
If a client device responds to the address packet with an ACK, the Write Interrupt Flag (WIF) is set to ‘1’, the
Received Acknowledge (RXACK) flag is set to ‘0’, and the Clock Hold (CLKHOLD) flag is set to ‘1’. The WIF, RXACK
and CLKHOLD flags are located in the Host Status (TWIn.MSTATUS) register.
The clock hold is active at this point, forcing the SCL low. This will stretch the low period of the clock to slow down the
overall clock frequency, forcing delays required to process the data and preventing further activity on the bus.
The software can prepare to:
• Transmit data packets to the client
Case M2: Address Packet Transmit Complete - Direction Bit Set to ‘1’
If a client device responds to the address packet with an ACK, the RXACK flag is set to ‘0’, and the client can start
sending data to the host without any delays because the client owns the bus at this moment. The clock hold is active
at this point, forcing the SCL low.
The software can prepare to:
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•
Read the received data packet from the client
Case M3: Address Packet Transmit Complete - Address not Acknowledged by Client
If no client device responds to the address packet, the WIF and the RXACK flags will be set to ‘1’. The clock hold is
active at this point, forcing the SCL low.
The missing ACK response can indicate that the I2C client is busy with other tasks, or it is in a sleep mode, and it is
not able to respond.
The software can prepare to take one of the following actions:
• Retransmit the address packet
• Complete the transaction by issuing a Stop condition in the Command (MCMD) bit field from the Host Control B
(TWIn.MCTRLB) register, which is the recommended action
Case M4: Arbitration Lost or Bus Error
If the arbitration is lost, both the WIF and the Arbitration Lost (ARBLOST) flags in the Host Status (TWIn.MSTATUS)
register are set to ‘1’. The SDA is disabled, and the SCL is released. The bus state changes to Busy, and the host is
no longer allowed to perform any operation on the bus until the bus state is changed back to Idle.
A bus error will behave similarly to the arbitration lost condition. In this case, the Bus Error (BUSERR) flag in the Host
Status (TWIn.MSTATUS) register is set to ‘1’, in addition to the WIF and ARBLOST flags.
The software can prepare to:
• Abort the operation and wait until the bus state changes to Idle by reading the Bus State (BUSSTATE) bit field in
the Host Status (TWIn.MSTATUS) register
26.3.2.2.4 Transmitting Data Packets
Assuming the above M1 case, the TWI host can start transmitting data by writing to the Host Data (TWIn.MDATA)
register, which will also clear the Write Interrupt Flag (WIF). During the data transfer, the host is continuously
monitoring the bus for collisions and errors. The WIF flag will be set to ‘1’ after the data packet transfer has been
completed.
If the transmission is successful and the host receives an ACK bit from the client, the Received Acknowledge
(RXACK) flag will be set to ‘0’, meaning that the client is ready to receive new data packets.
The software can prepare to take one of the following actions:
• Transmit a new data packet
• Transmit a new address packet
• Complete the transaction by issuing a Stop condition in the Command (MCMD) bit field from the Host Control B
(TWIn.MCTRLB) register
If the transmission is successful and the host receives a NACK bit from the client, the RXACK flag will be set to ‘1’,
meaning that the client is not able to or does not need to receive more data.
The software can prepare to take one of the following actions:
• Transmit a new address packet
• Complete the transaction by issuing a Stop condition in the Command (MCMD) bit field from the Host Control B
(TWIn.MCTRLB) register
The RXACK status is valid only if the WIF flag is set to ‘1’ and the Arbitration Lost (ARBLOST) and Bus Error
(BUSERR) flags are set to ‘0’.
The transmission can be unsuccessful if a collision is detected. Then, the host will lose the arbitration, the Arbitration
Lost (ARBLOST) flag will be set to ‘1’, and the bus state changes to Busy. An arbitration lost during the sending of
the data packet is treated the same way as the above M4 case.
The WIF, ARBLOST, BUSERR and RXACK flags are all located in the Host Status (TWIn.MSTATUS) register.
26.3.2.2.5 Receiving Data Packets
Assuming the M2 case above, the clock is released for one byte, allowing the client to put one byte of data on the
bus. The host will receive one byte of data from the client, and the Read Interrupt Flag (RIF) will be set to ‘1’ together
with the Clock Hold (CLKHOLD) flag. The action selected by the Acknowledge Action (ACKACT) bit in the Host
Control B (TWIn.MCTRLB) register is automatically sent on the bus when a command is written to the Command
(MCMD) bit field in the TWIn.MCTRLB register.
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The software can prepare to take one of the following actions:
• Respond with an ACK by writing ‘0’ to the ACKACT bit in the TWIn.MCTRLB register and prepare to receive a
new data packet
• Respond with a NACK by writing ‘1’ to the ACKACT bit and then transmit a new address packet
•
Respond with a NACK by writing ‘1’ to the ACKACT bit and then complete the transaction by issuing a Stop
condition in the MCMD bit field from the TWIn.MCTRLB register
A NACK response might not be successfully executed, as the arbitration can be lost during the transmission. If a
collision is detected, the host loses the arbitration, the Arbitration Lost (ARBLOST) flag is set to ‘1’, and the bus state
changes to Busy. The Host Write Interrupt Flag (WIF) is set if the arbitration was lost when sending a NACK or a bus
error occurred during the procedure. An arbitration lost during the sending of the data packet is treated in the same
way as the above M4 case.
The RIF, CLKHOLD, ARBLOST and WIF flags are all located in the Host Status (TWIn.MSTATUS) register.
Note: The RIF and WIF flags are mutually exclusive and cannot be set simultaneously.
26.3.2.3 TWI Client Operation
The TWI client is byte-oriented with optional interrupts after each byte. There are separate interrupt flags for the client
data and for address/Stop recognition. Interrupt flags can also be used for polled operation. There are dedicated
status flags for indicating ACK/NACK received, clock hold, collision, bus error, and R/W direction bit.
When an interrupt flag is set to ‘1’, the SCL is forced low. This will give the client time to respond or handle any data,
and will, in most cases, require software interaction. The number of interrupts generated is kept to a minimum by
automatic handling of most conditions.
The Address Recognition Mode (PMEN) bit in the Client Control A (TWIn.SCTRLA) register can be configured to
allow the client to respond to all received addresses.
26.3.2.3.1 Receiving Address Packets
When the TWI is configured as a client, it will wait for a Start condition to be detected. When this happens, the
successive address packet will be received and checked by the address match logic. The client will ACK a correct
address and store the address in the Client Data (TWIn.SDATA) register. If the received address is not a match, the
client will not acknowledge or store the address, but wait for a new Start condition.
The Address or Stop Interrupt Flag (APIF) in the Client Status (TWIn.SSTATUS) register is set to ‘1’ when a Start
condition is succeeded by one of the following:
•
•
A valid address match with the address stored in the Address (ADDR[7:1]) bit field in the Client Address
(TWIn.SADDR) register
The General Call Address (0x00), and the Address (ADDR[0]) bit in the Client Address (TWIn.SADDR) register
is set to ‘1’
•
A valid address match with the secondary address stored in the Address Mask (ADDRMASK) bit field, and the
Address Mask Enable (ADDREN) bit is set to ‘1’ in the Client Address Mask (TWIn.SADDRMASK) register
•
Any address if the Address Recognition Mode (PMEN) bit in the Client Control A (TWIn.SCTRLA) register is set
to ‘1’
Depending on the Read/Write Direction (DIR) bit in the Client Status (TWIn.SSTATUS) register and the bus condition,
one of four distinct cases (S1 to S4) arises after the reception of the address packet.
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Figure 26-6. TWI Client Operation
CLIENT ADDRESS INTERRUPT
S4
S3
IF
S
A
ADDRESS
R
IF
Interrupt flag raised
Addressed client provides
data on the bus
W
IF
Interrupton STOP
Condition Enabled
IF
P
S3
Sr
S4
S3
Sr
S4
A
S3
Sr
S4
P
S3
A
Sr
S4
A
Sr
S4
A
IF
P
P
S3
P
A
A
The host provides data
on the bus
Sn
CLIENT DATA INTERRUPT
S2
DATA
A
S3
P
DATA
IF
S1
Diagram cases
Case S1: Address Packet Accepted - Direction Bit Set to ‘0’
If an ACK is sent by the client after the address packet is received, and the Read/Write Direction (DIR) bit in the
Client Status (TWIn.SSTATUS) register is set to ‘0’, the host indicates a write operation.
The clock hold is active at this point, forcing the SCL low. This will stretch the low period of the clock to slow down the
overall clock frequency, forcing delays required to process the data and preventing further activity on the bus.
The software can prepare to:
• Read the received data packet from the host
Case S2: Address Packet Accepted - Direction Bit Set to ‘1’
If an ACK is sent by the client after the address packet is received, and the DIR bit is set to ‘1’, the host indicates a
read operation, and the Data Interrupt Flag (DIF) in the Client Status (TWIn.SSTATUS) register will be set to ‘1’.
The clock hold is active at this point, forcing the SCL low.
The software can prepare to:
• Transmit data packets to the host
Case S3: Stop Condition Received
When the Stop condition is received, the Address or Stop (AP) flag will be set to ‘0’, indicating that a Stop condition,
and not an address match, activated the Address or Stop Interrupt Flag (APIF).
The AP and APIF flags are located in the Client Status (TWIn.SSTATUS) register.
The software can prepare to:
• Wait until a new address packet has been addressed to it
Case S4: Collision
If the client is not able to send a high-level data bit or a NACK, the Collision (COLL) bit in the Client Status
(TWIn.SSTATUS) register is set to ‘1’. The client will commence its operation as normal, except no low values will be
shifted out on the SDA. The data and acknowledge output from the client logic will be disabled. The clock hold is
released. A Start or repeated Start condition will be accepted.
The COLL bit is intended for systems where the Address Resolution Protocol (ARP) is employed. A detected collision
in non-ARP situations indicates that there has been a protocol violation and must be treated as a bus error.
26.3.2.3.2 Receiving Data Packets
Assuming the above S1 case, the client must be ready to receive data. When a data packet is received, the Data
Interrupt Flag (DIF) in the Client Status (TWIn.SSTATUS) register is set to ‘1’. The action selected by the
Acknowledge Action (ACKACT) bit in the Client Control B (TWIn.SCTRLB) register is automatically sent on the bus
when a command is written to the Command (SCMD) bit field in the TWIn.SCTRLB register.
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The software can prepare to take one of the following actions:
• Respond with an ACK by writing ‘0’ to the ACKACT bit in the TWIn.SCTRLB register, indicating that the client is
ready to receive more data
• Respond with a NACK by writing ‘1’ to the ACKACT bit, indicating that the client cannot receive any more data
and the host must issue a Stop or repeated Start condition
26.3.2.3.3 Transmitting Data Packets
Assuming the above S2 case, the client can start transmitting data by writing to the Client Data (TWIn.SDATA)
register. When a data packet transmission is completed, the Data Interrupt Flag (DIF) in the Client Status
(TWIn.SSTATUS) register is set to ‘1’.
The software can prepare to take one of the following actions:
• Check if the host responded with an ACK by reading the Received Acknowledge (RXACK) bit from the Client
Status (TWIn.SSTATUS) register, and start transmitting new data packets
• Check if the host responded with a NACK by reading the RXACK bit, and stop transmitting data packets. The
host must send a Stop or repeated Start condition after the NACK.
26.3.3
Additional Features
26.3.3.1 SMBus
If the TWI is used in an SMBus environment, the Inactive Bus Time-Out (TIMEOUT) bit field from the Host Control A
(TWIn.MCTRLA) register must be configured. It is recommended to write to the Host Baud Rate (TWIn.MBAUD)
register before setting the time-out because it is dependent on the baud rate setting.
A frequency of 100 kHz can be used for the SMBus environment. For the Standard mode (Sm) and Fast mode (Fm),
the operating frequency has slew rate limited output, while for the Fast mode Plus (Fm+), it has x10 output drive
strength.
The TWI also allows for an SMBus compatible SDA hold time configured in the SDA Hold Time (SDAHOLD) bit field
from the Control A (TWIn.CTRLA) register.
26.3.3.2 Multi-Host
A host can start a bus transaction only if it has detected that the bus is in the Idle state. As the TWI bus is a multi-host
bus, more devices may try to initiate a transaction at the same time. This results in multiple hosts owning the bus
simultaneously. The TWI solves this problem by using an arbitration scheme where the host loses control of the bus if
it is not able to transmit a high-level data bit on the SDA and the Bus State (BUSSTATE) bit field from the Host Status
(TWIn.MSTATUS) register will be changed to Busy. The hosts that lose the arbitration must wait until the bus
becomes Idle before attempting to reacquire the bus ownership.
Both devices can issue a Start condition, but DEVICE1 loses arbitration when attempting to transmit a high-level (bit
5) while DEVICE2 is transmitting a low-level.
Figure 26-7. TWI Arbitration
DEVICE1 Loses arbitration
DEVICE1_SDA
DEVICE2_SDA
SDA
(wired-AND)
bit 7
bit 6
bit 5
bit 4
SCL
S
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26.3.3.3 Smart Mode
The TWI interface has a Smart mode that simplifies the application code and minimizes the user interaction needed
to adhere to the I2C protocol.
For the TWI host, the Smart mode will automatically send the ACK action as soon as the Host Data (TWIn.MDATA)
register is read. This feature is only active when the Acknowledge Action (ACKACT) bit in the Host Control B
(TWIn.MCTRLB) register is set to ACK. If the ACKACT bit is set to NACK, the TWI host will not generate a NACK
after the MDATA register is read. This feature is enabled when the Smart Mode Enable (SMEN) bit in the Host
Control A (TWIn.MCTRLA) register is set to ‘1’.
For the TWI client, the Smart mode will automatically send the ACK action as soon as the Client Data (TWIn.SDATA)
register is read. The Smart mode will automatically set the Data Interrupt Flag (DIF) to ‘0’ in the Client Status
(TWIn.SSTATUS) register if the TWIn.SDATA register is read or written. This feature is enabled when the Smart
Mode Enable (SMEN) bit in the Client Control A (TWIn.SCTRLA) register is set to ‘1’.
26.3.3.4 Quick Command Mode
With Quick Command mode, the R/W bit from the address packet denotes the command. This mode is enabled by
writing ‘1’ to the Quick Command Enable (QCEN) bit in the Host Control A (TWIn.MCTRLA) register. There are no
data sent or received.
The Quick Command mode is SMBus specific, where the R/W bit can be used to turn a device function on/off or to
enable/disable a low-power Standby mode. This mode can be enabled to auto-trigger operations and reduce
software complexity.
After the host receives an ACK from the client, either the Read Interrupt Flag (RIF) or Write Interrupt Flag (WIF) will
be set, depending on the value of the R/W bit. When either the RIF or WIF flag is set after issuing a Quick Command,
the TWI will accept a Stop command by writing the Command (MCMD) bit field in the Host Control B
(TWIn.MCTRLB) register.
The RIF and WIF flags, together with the value of the last Received Acknowledge (RXACK) flag, are all located in the
Host Status (TWIn.MSTATUS) register.
Figure 26-8. Quick Command Frame Format
BUSY
P
BUSY
IDLE
S
ADDRESS
R/W
OWNER
A
P
The host provides data
on the bus
Addressed client provides
data on the bus
26.3.3.5 10-bit Address
Regardless of whether the transaction is a read or write, the host must start by sending the 10-bit address with the
R/W direction bit set to ‘0’.
The client address match logic supports recognition of 7-bit addresses and General Call Address. The Client Address
(TWIn.SADDR) register is used by the client address match logic to determine if a host device has addressed the
TWI client.
The TWI client address match logic only supports recognition of the first byte of a 10-bit address, and the second
byte must be handled in software. The first byte of the 10-bit address will be recognized if the upper five bits of the
Client Address (TWIn.SADDR) register are 0b11110. Thus, the first byte will consist of five indication bits, the two
Most Significant bits (MSb) of the 10-bits address, and the R/W direction bit. The Least Significant Byte (LSB) of the
address that follows from the host will come in the form of a data packet.
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TWI - Two-Wire Interface
Figure 26-9. 10-bit Address Transmission
S
SW
1
1
1
0
1
A9
A8
W
A
A7 A6
A5
A4
A3
A2
A1
A0
A
S
W
Software interaction
The host provides data
on the bus
Addressed client provides
data on the bus
26.3.4
Interrupts
Table 26-1. Available Interrupt Vectors and Sources
Name
Vector Description
Client
TWI Client interrupt
Host
TWI Host interrupt
Conditions
•
DIF: Data Interrupt Flag in TWIn.SSTATUS is set to ‘1’
•
APIF: Address or Stop Interrupt Flag in TWIn.SSTATUS is set to ‘1’
•
RIF: Read Interrupt Flag in TWIn.MSTATUS is set to ‘1’
•
WIF: Write Interrupt Flag in TWIn.MSTATUS is set to ‘1’
When an interrupt condition occurs, the corresponding interrupt flag is set in the Host Status (TWIn.MSTATUS)
register or the Client Status (TWIn.SSTATUS) register.
When several interrupt request conditions are supported by an interrupt vector, the interrupt requests are ORed
together into one combined interrupt request to the interrupt controller. The user must read the interrupt flags from the
TWIn.MSTATUS register or the TWIn.SSTATUS register to determine which of the interrupt conditions are present.
26.3.5
Sleep Mode Operation
The bus state logic and the address recognition hardware continue to operate in all sleep modes. If a client device is
in a sleep mode and a Start condition followed by the address of the client is detected, clock stretching is active
during the wake-up period until the main clock is available. The host will stop operation in all sleep modes.
26.3.6
Debug Operation
During run-time debugging, the TWI will continue normal operation. Halting the CPU in Debugging mode will halt the
normal operation of the TWI. The TWI can be forced to operate with a halted CPU by writing a ‘1’ to the Debug Run
(DBGRUN) bit in the Debug Control (TWIn.DBGCTRL) register. When the CPU is halted in Debug mode, and the
DBGRUN bit is ‘1’, reading or writing the Host Data (TWIn.MDATA) register or the Client Data (TWIn.SDATA) register
will neither trigger a bus operation nor cause transmit and clear flags. If the TWI is configured to require periodical
service by the CPU through interrupts or similar, improper operation or data loss may result during halted debugging.
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TWI - Two-Wire Interface
26.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
CTRLA
Reserved
DBGCTRL
MCTRLA
MCTRLB
MSTATUS
MBAUD
MADDR
MDATA
SCTRLA
SCTRLB
SSTATUS
SADDR
SDATA
SADDRMASK
7:0
26.5
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7
6
5
4
SDASETUP
RIEN
WIEN
RIF
WIF
DIEN
APIEN
DIF
APIF
QCEN
3
2
SDAHOLD[1:0]
TIMEOUT[1:0]
FLUSH
ACKACT
CLKHOLD
RXACK
ARBLOST
BUSERR
BAUD[7:0]
ADDR[7:0]
DATA[7:0]
PIEN
PMEN
ACKACT
CLKHOLD
RXACK
COLL
BUSERR
ADDR[7:0]
DATA[7:0]
ADDRMASK[6:0]
1
0
FMPEN
DBGRUN
SMEN
ENABLE
MCMD[1:0]
BUSSTATE[1:0]
SMEN
ENABLE
SCMD[1:0]
DIR
AP
ADDREN
Register Description
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26.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
7
CTRLA
0x00
0x00
-
6
Access
Reset
5
4
SDASETUP
R/W
0
3
2
SDAHOLD[1:0]
R/W
R/W
0
0
1
FMPEN
R/W
0
0
Bit 4 – SDASETUP SDA Setup Time
This bit is used in TWI Client mode to select the clock hold time and to ensure the minimum setup time on the SDA
out signal.
Value
Name
Description
0
4CYC
SDA setup time is four clock cycles
1
8CYC
SDA setup time is eight clock cycles
Bits 3:2 – SDAHOLD[1:0] SDA Hold Time
This bit field selects the SDA hold time for the TWI. See the Electrical Characteristics section for details.
Value
Name
Description
0x0
OFF
Hold time OFF
0x1
50NS
Short hold time
0x2
300NS
Meets the SMBus 2.0 specifications under typical conditions
0x3
500NS
Meets the SMBus 2.0 across all corners
Bit 1 – FMPEN FM Plus Enable
Writing a ‘1’ to this bit selects the 1 MHz bus speed for the TWI in the default configuration.
Value
Name
Description
0
OFF
Operating in Standard mode or Fast mode
1
ON
Operating in Fast mode Plus
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26.5.2
Debug Control
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x02
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Refer to the Debug Operation section for details.
Value
Description
0
The TWI is halted in Break Debug mode and ignores events
1
The TWI will continue to run in Break Debug mode when the CPU is halted
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26.5.3
Host Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RIEN
R/W
0
MCTRLA
0x03
0x00
-
6
WIEN
R/W
0
5
4
QCEN
R/W
0
3
2
TIMEOUT[1:0]
R/W
R/W
0
0
1
SMEN
R/W
0
0
ENABLE
R/W
0
Bit 7 – RIEN Read Interrupt Enable
A TWI host read interrupt will be generated only if this bit and the Global Interrupt Enable (I) bit in the Status
(CPU.SREG) register are set to ‘1’.
Writing a ‘1’ to this bit enables the interrupt on the Read Interrupt Flag (RIF) in the Host Status (TWIn.MSTATUS)
register. When the host read interrupt occurs, the RIF flag is set to ‘1’.
Bit 6 – WIEN Write Interrupt Enable
A TWI host write interrupt will be generated only if this bit and the Global Interrupt Enable (I) bit in the Status
(CPU.SREG) register are set to ‘1’.
Writing a ‘1’ to this bit enables the interrupt on the Write Interrupt Flag (WIF) in the Host Status (TWIn.MSTATUS)
register. When the host write interrupt occurs, the WIF flag is set to ‘1’.
Bit 4 – QCEN Quick Command Enable
Writing a ‘1’ to this bit enables the Quick Command mode. If the Quick Command mode is enabled and a client
acknowledges the address, the corresponding Read Interrupt Flag (RIF) or Write Interrupt Flag (WIF) will be set
depending on the value of the R/W bit.
The software must issue a Stop command by writing to the Command (MCMD) bit field in the Host Control B
(TWIn.MCTRLB) register.
Bits 3:2 – TIMEOUT[1:0] Inactive Bus Time-Out
Setting this bit field to a nonzero value will enable the inactive bus time-out supervisor. If the bus is inactive for longer
than the TIMEOUT setting, the bus state logic will enter the Idle state.
Value
Name
Description
0x0
DISABLED
Bus time-out disabled - I2C
0x1
50US
50 µs - SMBus (assume the baud rate is set to 100 kHz)
0x2
100US
100 µs (assume the baud rate is set to 100 kHz)
0x3
200US
200 µs (assume the baud rate is set to 100 kHz)
Bit 1 – SMEN Smart Mode Enable
Writing a ‘1’ to this bit enables the Host Smart mode. When the Smart mode is enabled, the existing value in the
Acknowledge Action (ACKACT) bit from the Host Control B (TWIn.MCTRLB) register is sent immediately after
reading the Host Data (TWIn.MDATA) register.
Bit 0 – ENABLE Enable TWI Host
Writing a ‘1’ to this bit enables the TWI as host.
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26.5.4
Host Control B
Name:
Offset:
Reset:
Property:
Bit
MCTRLB
0x04
0x00
-
7
6
5
4
Access
Reset
3
FLUSH
R/W
0
2
ACKACT
R/W
0
1
0
MCMD[1:0]
R/W
0
R/W
0
Bit 3 – FLUSH Flush
This bit clears the internal state of the host and the bus states changes to Idle. The TWI will transmit invalid data if
the Host Data (TWIn.MDATA) register is written before the Host Address (TWIn.MADDR) register.
Writing a ‘1’ to this bit generates a strobe for one clock cycle, disabling the host and then re-enabling the host. Writing
a ‘0’ to this bit has no effect.
Bit 2 – ACKACT Acknowledge Action
The ACKACT(1) bit represents the behavior in the Host mode under certain conditions defined by the bus state and
the software interaction. If the Smart Mode Enable (SMEN) bit in the Host Control A (TWIn.MCTRLA) register is set
to ‘1’, the acknowledge action is performed when the Host Data (TWIn.MDATA) register is read, else a command
must be written to the Command (MCDM) bit field in the Host Control B (TWIn.MCTRLB) register.
The acknowledge action is not performed when the Host Data (TWIn.MDATA) register is written since the host is
sending data.
Value
Name
Description
0
ACK
Send ACK
1
NACK
Send NACK
Bits 1:0 – MCMD[1:0] Command
The MCMD(1) bit field is a strobe. This bit field is always read as ‘0’.
Writing to this bit field triggers a host operation, as defined by the table below.
Table 26-2. Command Settings
MCMD[1:0]
Group
Configuration
DIR
Description
0x0
NOACT
X
Reserved
0x1
REPSTART
0x2
RECVTRANS
0x3
STOP
X
Execute Acknowledge Action followed by repeated Start condition
W
Execute Acknowledge Action (no action) followed by a byte write operation(2)
R
Execute Acknowledge Action followed by a byte read operation
X
Execute Acknowledge Action followed by issuing a Stop condition
Notes:
1. The ACKACT bit and the MCMD bit field can be written at the same time.
2. For a host write operation, the TWI will wait for new data to be written to the Host Data (TWIn.MDATA) register.
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26.5.5
Host Status
Name:
Offset:
Reset:
Property:
Bit
7
RIF
R/W
0
Access
Reset
MSTATUS
0x05
0x00
-
6
WIF
R/W
0
5
CLKHOLD
R/W
0
4
RXACK
R
0
3
ARBLOST
R/W
0
2
BUSERR
R/W
0
1
0
BUSSTATE[1:0]
R/W
R/W
0
0
Bit 7 – RIF Read Interrupt Flag
This flag is set to ‘1’ when the host byte read operation is completed.
The RIF flag can be used for a host read interrupt. More information can be found in the Read Interrupt Enable
(RIEN) bit from the Host Control A (TWIn.MCTRLA) register.
This flag is automatically cleared when accessing several other TWI registers. The RIF flag can be cleared by
choosing one of the following methods:
1. Writing a ‘1’ to it.
2.
3.
4.
Writing to the Host Address (TWIn.MADDR) register.
Writing/Reading the Host Data (TWIn.MDATA) register.
Writing to the Command (MCMD) bit field from the Host Control B (TWIn.MCTRLB) register.
Bit 6 – WIF Write Interrupt Flag
This flag is set to ‘1’ when a host transmit address or byte write operation is completed, regardless of the occurrence
of a bus error or arbitration lost condition.
The WIF flag can be used for a host write interrupt. More information can be found from the Write Interrupt Enable
(WIEN) bit in the Host Control A (TWIn.MCTRLA) register.
This flag can be cleared by choosing one of the methods described for the RIF flag.
Bit 5 – CLKHOLD Clock Hold
When this bit is read as ‘1’, it indicates that the host is currently holding the SCL low, stretching the TWI clock period.
This bit can be cleared by choosing one of the methods described for the RIF flag.
Bit 4 – RXACK Received Acknowledge
When this flag is read as ‘0’, it indicates that the most recent Acknowledge bit from the client was ACK, and the client
is ready for more data.
When this flag is read as ‘1’, it indicates that the most recent Acknowledge bit from the client was NACK, and the
client is not able to or does not need to receive more data.
Bit 3 – ARBLOST Arbitration Lost
When this bit is read as ‘1’, it indicates that the host has lost arbitration. This can happen in one of the following
cases:
1. While transmitting a high data bit.
2. While transmitting a NACK bit.
3. While issuing a Start condition (S).
4. While issuing a repeated Start (Sr).
This flag can be cleared by choosing one of the methods described for the RIF flag.
Bit 2 – BUSERR Bus Error
The BUSERR flag indicates that an illegal bus operation has occurred. An illegal bus operation is detected if a
protocol violating the Start (S), repeated Start (Sr), or Stop (P) conditions is detected on the TWI bus lines. A Start
condition directly followed by a Stop condition is one example of a protocol violation.
The BUSERR flag can be cleared by choosing one of the following methods:
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TWI - Two-Wire Interface
1.
Writing a ‘1’ to it.
2.
Writing to the Host Address (TWIn.MADDR) register.
The TWI bus error detector is part of the TWI host circuitry. For the bus errors to be detected, the TWI host must be
enabled (ENABLE bit in TWIn.MCTRLA is ‘1’), and the main clock frequency must be at least four times the SCL
frequency.
Bits 1:0 – BUSSTATE[1:0] Bus State
This bit field indicates the current TWI bus state.
Value
Name
Description
0x0
UNKNOWN
Unknown bus state
0x1
IDLE
Idle bus state
0x2
OWNER
This TWI controls the bus
0x3
BUSY
Busy bus state
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26.5.6
Host Baud Rate
Name:
Offset:
Reset:
Property:
Bit
7
MBAUD
0x06
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
BAUD[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – BAUD[7:0] Baud Rate
This bit field is used to derive the SCL high and low time. It must be written while the host is disabled. The host can
be disabled by writing ‘0’ to the Enable TWI Host (ENABLE) bit from the Host Control A (TWIn.MCTRLA) register.
Refer to the Clock Generation section for more information on how to calculate the frequency of the SCL.
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26.5.7
Host Address
Name:
Offset:
Reset:
Property:
Bit
7
MADDR
0x07
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
ADDR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – ADDR[7:0] Address
This register contains the address of the external client device. When this bit field is written, the TWI will issue a Start
condition, and the shift register performs a byte transmit operation on the bus depending on the bus state.
This register can be read at any time without interfering with the ongoing bus activity since a read access does not
trigger the host logic to perform any bus protocol related operations.
The host control logic uses the bit 0 of this register as the R/W direction bit.
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26.5.8
Host Data
Name:
Offset:
Reset:
Property:
Bit
7
MDATA
0x08
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DATA[7:0] Data
This bit field provides direct access to the host’s physical shift register, which is used to shift out data on the bus
(transmit) and to shift in data received from the bus (receive). The direct access implies that the MDATA register
cannot be accessed during byte transmissions.
Reading valid data or writing data to be transmitted can only be successful when the CLKHOLD bit is read as ‘1’ or
when an interrupt occurs.
A write access to the MDATA register will command the host to perform a byte transmit operation on the bus, directly
followed by receiving the Acknowledge bit from the client. This is independent of the Acknowledge Action (ACKACT)
bit from the Host Control B (TWIn.MCTRLB) register. The write operation is performed regardless of winning or losing
arbitration before the Write Interrupt Flag (WIF) is set to ‘1’.
If the Smart Mode Enable (SMEN) bit in the Host Control A (TWIn.MCTRLA) register is set to ‘1’, a read access to
the MDATA register will command the host to perform an acknowledge action. This is dependent on the setting of the
Acknowledge Action (ACKACT) bit from the Host Control B (TWIn.MCTRLB) register.
Notes:
1. The WIF and RIF flags are cleared automatically if the MDATA register is read while ACKACT is set to ‘1’.
2.
3.
The ARBLOST and BUSEER flags are left unchanged.
The WIF, RIF, ARBLOST, and BUSERR flags together with the Clock Hold (CLKHOLD) bit are all located in
the Host Status (TWIn.MSTATUS) register.
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26.5.9
Client Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
DIEN
R/W
0
SCTRLA
0x09
0x00
-
6
APIEN
R/W
0
5
PIEN
R/W
0
4
3
2
PMEN
R/W
0
1
SMEN
R/W
0
0
ENABLE
R/W
0
Bit 7 – DIEN Data Interrupt Enable
Writing this bit to ‘1’ enables an interrupt on the Data Interrupt Flag (DIF) from the Client Status (TWIn.SSTATUS)
register.
A TWI client data interrupt will be generated only if this bit, the DIF flag, and the Global Interrupt Enable (I) bit in
Status (CPU.SREG) register are all ‘1’.
Bit 6 – APIEN Address or Stop Interrupt Enable
Writing this bit to ‘1’ enables an interrupt on the Address or Stop Interrupt Flag (APIF) from the Client Status
(TWIn.SSTATUS) register.
A TWI client address or stop interrupt will be generated only if this bit, the APIF flag, and the Global Interrupt Enable
(I) bit in the Status (CPU.SREG) register are all ‘1’.
Notes:
1. The client stop interrupt shares the interrupt flag and vector with the client address interrupt.
2. The Stop Interrupt Enable (PIEN) bit in the Client Control A (TWIn.SCTRLA) register must be written to ‘1’ for
the APIF to be set on a Stop condition.
3. When the interrupt occurs, the Address or Stop (AP) bit in the Client Status (TWIn.SSTATUS) register will
determine whether an address match or a Stop condition caused the interrupt.
Bit 5 – PIEN Stop Interrupt Enable
Writing this bit to ‘1’ allows the Address or Stop Interrupt Flag (APIF) in the Client Status (TWIn.SSTATUS) register to
be set when a Stop condition occurs. To use this feature, the main clock frequency must be at least four times the
SCL frequency.
Bit 2 – PMEN Address Recognition Mode
If this bit is written to ‘1’, the client address match logic responds to all received addresses.
If this bit is written to ‘0’, the address match logic uses the Client Address (TWIn.SADDR) register to determine which
address to recognize as the client’s address.
Bit 1 – SMEN Smart Mode Enable
Writing this bit to ‘1’ enables the client Smart mode. When the Smart mode is enabled, issuing a command by writing
to the Command (SCMD) bit field in the Client Control B (TWIn.SCTRLB) register or accessing the Client Data
(TWIn.SDATA) register resets the interrupt, and the operation continues. If the Smart mode is disabled, the client
always waits for a new client command before continuing.
Bit 0 – ENABLE Enable TWI Client
Writing this bit to ‘1’ enables the TWI client.
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26.5.10 Client Control B
Name:
Offset:
Reset:
Property:
Bit
SCTRLB
0x0A
0x00
-
7
6
5
4
3
Access
Reset
2
ACKACT
R/W
0
1
0
SCMD[1:0]
R/W
0
R/W
0
Bit 2 – ACKACT Acknowledge Action
The ACKACT(1) bit represents the behavior of the client device under certain conditions defined by the bus protocol
state and the software interaction. If the Smart Mode Enable (SMEN) bit in the Client Control A (TWIn.SCTRLA)
register is set to ‘1’, the acknowledge action is performed when the Client Data (TWIn.SDATA) register is read, else a
command must be written to the Command (SCMD) bit field in the Client Control B (TWIn.SCTRLB) register.
The acknowledge action is not performed when the Client Data (TWIn.SDATA) register is written since the client is
sending data.
Value
Name
Description
0
ACK
Send ACK
1
NACK
Send NACK
Bits 1:0 – SCMD[1:0] Command
The SCMD(1) bit field is a strobe. This bit field is always read as ‘0’.
Writing to this bit field triggers a client operation as defined by the table below.
Table 26-3. Command Settings
Value Name
0x0
0x1
NOACT
—
0x2
COMPTRANS
DIR Description
X
X
W
R
W
0x3
RESPONSE
R
No action
Reserved
Execute Acknowledge Action succeeded by waiting
for any Start (S/Sr) condition
Used to complete a transaction
Wait for any Start (S/Sr) condition
Execute Acknowledge Action succeeded by reception of next byte
Used in response to an address interrupt (APIF): Execute Acknowledge Action
succeeded by client data interrupt.
Used in response to a data interrupt (DIF): Execute a byte read operation followed by
Acknowledge Action.
Note: 1. The ACKACT bit and the SCMD bit field can be written at the same time. The ACKACT will be updated
before the command is triggered.
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TWI - Two-Wire Interface
26.5.11 Client Status
Name:
Offset:
Reset:
Property:
Bit
7
DIF
R/W
0
Access
Reset
SSTATUS
0x0B
0x00
-
6
APIF
R/W
0
5
CLKHOLD
R
0
4
RXACK
R
0
3
COLL
R/W
0
2
BUSERR
R/W
0
1
DIR
R
0
0
AP
R
0
Bit 7 – DIF Data Interrupt Flag
This flag is set to ‘1’ when the client byte transmit or receive operation is completed without any bus errors. This flag
can be set to ‘1’ with an unsuccessful transaction in case of collision detection. More information can be found in the
Collision (COLL) bit description.
The DIF flag can generate a client data interrupt. More information can be found in Data Interrupt Enable (DIEN) bit
from the Client Control A (TWIn.SCTRLA) register.
This flag is automatically cleared when accessing several other TWI registers. The DIF flag can be cleared by
choosing one of the following methods:
1. Writing/Reading the Client Data (TWIn.SDATA) register.
2. Writing to the Command (SCMD) bit field from the Client Control B (TWIn.SCTRLB) register.
Bit 6 – APIF Address or Stop Interrupt Flag
This flag is set to ‘1’ when the client address has been received or by a Stop condition.
The APIF flag can generate a client address or stop interrupt. More information can be found in the Address or Stop
Interrupt Enable (APIEN) bit from the Client Control A (TWIn.SCTRLA) register.
This flag can be cleared by choosing one of the methods described for the DIF flag.
Bit 5 – CLKHOLD Clock Hold
When this bit is read as ‘1’, it indicates that the client is currently holding the SCL low, stretching the TWI clock
period.
This bit is set to ‘1’ when an address or data interrupt occurs. Resetting the corresponding interrupt will indirectly set
this bit to ‘0’.
Bit 4 – RXACK Received Acknowledge
When this flag is read as ‘0’, it indicates that the most recent Acknowledge bit from the host was ACK.
When this flag is read as ‘1’, it indicates that the most recent Acknowledge bit from the host was NACK.
Bit 3 – COLL Collision
When this bit is read as ‘1’, it indicates that the client has not been able to do one of the following:
1.
2.
Transmit high bits on the SDA. The Data Interrupt Flag (DIF) will be set to ‘1’ at the end as a result of the
internal completion of an unsuccessful transaction.
Transmit the NACK bit. The collision occurs because the client address match already took place, and the
APIF flag is set to ‘1’ as a result.
Writing a ‘1’ to this bit will clear the COLL flag. The flag is automatically cleared if any Start condition (S/Sr) is
detected.
Note: The APIF and DIF flags can only generate interrupts whose handlers can be used to check for the collision.
Bit 2 – BUSERR Bus Error
The BUSERR flag indicates that an illegal bus operation has occurred. Illegal bus operation is detected if a protocol
violating the Start (S), repeated Start (Sr), or Stop (P) conditions is detected on the TWI bus lines. A Start condition
directly followed by a Stop condition is one example of a protocol violation.
Writing a ‘1’ to this bit will clear the BUSERR flag.
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TWI - Two-Wire Interface
The TWI bus error detector is part of the TWI host circuitry. For the bus errors to be detected by the client, the TWI
host must be enabled, and the main clock frequency must be at least four times the SCL frequency. The TWI host
can be enabled by writing a ‘1’ to the ENABLE bit in the TWIn.MCTRLA register.
Bit 1 – DIR Read/Write Direction
This bit indicates the current TWI bus direction. The DIR bit reflects the direction bit value from the last address
packet received from a host TWI device.
When this bit is read as ‘1’, it indicates that a host read operation is in progress.
When this bit is read as ‘0’, it indicates that a host write operation is in progress.
Bit 0 – AP Address or Stop
When the TWI client Address or Stop Interrupt Flag (APIF) is set to ‘1’, this bit determines whether the interrupt is
due to an address detection or a Stop condition.
Value
Name
Description
0
STOP
A Stop condition generated the interrupt on the APIF flag
1
ADR
Address detection generated the interrupt on the APIF flag
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TWI - Two-Wire Interface
26.5.12 Client Address
Name:
Offset:
Reset:
Property:
Bit
7
SADDR
0x0C
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
ADDR[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – ADDR[7:0] Address
The Client Address (TWIn.SADDR) register is used by the client address match logic to determine if a host device
has addressed the TWI client. The Address or Stop Interrupt Flag (APIF) and the Address or Stop (AP) bit in the
Client Status (TWIn.SSTATUS) register are set to ‘1’ if an address packet is received.
The upper seven bits (ADDR[7:1]) of the TWIn.SADDR register represent the main client address.
The Least Significant bit (ADDR[0]) of the TWIn.SADDR register is used for the recognition of the General Call
Address (0x00) of the I2C protocol. This feature is enabled when this bit is set to ‘1’.
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TWI - Two-Wire Interface
26.5.13 Client Data
Name:
Offset:
Reset:
Property:
Bit
7
SDATA
0x0D
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DATA[7:0] Data
This bit field provides access to the client data register.
Reading valid data or writing data to be transmitted can only be achieved when the SCL is held low by the client (i.e.,
when the client CLKHOLD bit is set to ‘1’). It is not necessary to check the Clock Hold (CLKHOLD) bit from the Client
Status (TWIn.SSTATUS) register in software before accessing the SDATA register if the software keeps track of the
present protocol state by using interrupts or observing the interrupt flags.
If the Smart Mode Enable (SMEN) bit in the Client Control A (TWIn.SCTRLA) register is set to ‘1’, a read access to
the SDATA register, when the clock hold is active, auto-triggers bus operations and will command the client to
perform an acknowledge action. This is dependent on the setting of the Acknowledge Action (ACKACT) bit from the
Client Control B (TWIn.SCTRLB) register.
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TWI - Two-Wire Interface
26.5.14 Client Address Mask
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
SADDRMASK
0x0E
0x00
-
7
6
5
R/W
0
R/W
0
R/W
0
4
ADDRMASK[6:0]
R/W
0
3
2
1
R/W
0
R/W
0
R/W
0
0
ADDREN
R/W
0
Bits 7:1 – ADDRMASK[6:0] Address Mask
The ADDRMASK bit field acts as a second address match or an address mask register depending on the ADDREN
bit.
If the ADDREN bit is written to ‘0’, the ADDRMASK bit field can be loaded with a 7-bit Client Address mask. Each of
the bits in the Client Address Mask (TWIn.SADDRMASK) register can mask (disable) the corresponding address bits
in the TWI Client Address (TWIn.SADDR) register. When a bit from the mask is written to ‘1’, the address match logic
ignores the comparison between the incoming address bit and the corresponding bit in the Client Address
(TWIn.SADDR) register. In other words, masked bits will always match, making it possible to recognize the ranges of
addresses.
If the ADDREN bit is written to ‘1’, the Client Address Mask (TWIn.SADDRMASK) register can be loaded with a
second client address in addition to the Client Address (TWIn.SADDR) register. In this mode, the client will have two
unique addresses, one in the Client Address (TWIn.SADDR) register and the other one in the Client Address Mask
(TWIn.SADDRMASK) register.
Bit 0 – ADDREN Address Mask Enable
If this bit is written to ‘0’, the TWIn.SADDRMASK register acts as a mask to the TWIn.SADDR register.
If this bit is written to ‘1’, the client address match logic responds to the two unique addresses in the client
TWIn.SADDR and TWIn.SADDRMASK registers.
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.
CRCSCAN - Cyclic Redundancy Check Memory Scan
27.1
Features
•
•
•
•
27.2
CRC-16-CCITT
Check of the Entire Flash Section, Application Code, and/or Boot Section
Selectable NMI Trigger on Failure
User-Configurable Check During Internal Reset Initialization
Overview
A Cyclic Redundancy Check (CRC) takes a data stream of bytes from the NVM (either the entire Flash, only the Boot
section, or both the Boot section and the application code section) and generates a checksum. The CRC peripheral
(CRCSCAN) can be used to detect errors in the program memory.
The last location in the section to check has to contain the correct pre-calculated 16-bit checksum for comparison. If
the checksum calculated by the CRCSCAN and the pre-calculated checksums match, a status bit is set. If they do
not match, the Status register (CRCSCAN.STATUS) will indicate that it failed. The user can choose to let the
CRCSCAN generate a Non-Maskable Interrupt (NMI) if the checksums do not match.
An n-bit CRC applied to a data block of arbitrary length will detect any single alteration (error burst) up to n bits in
length. For longer error bursts a fraction 1-2-n will be detected.
The CRC generator supports CRC-16-CCITT.
Polynomial:
•
CRC-16-CCITT: x16 + x12 + x5 + 1
The CRC reads byte-by-byte the content of the section(s) it is set up to check, starting with byte 0, and generates a
new checksum per byte. The byte is sent through a shift register as depicted below, starting with the Most Significant
bit. If the last bytes in the section contain the correct checksum, the CRC will pass. See 27.3.2.1 Checksum for how
to place the checksum. The initial value of the Checksum register is 0xFFFF.
Figure 27-1. CRC Implementation Description
data
15
x14
x13
x12
x11
x10
x9
x8
x7
x6
x5
x4
x3
x2
x1
x0
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
Q D
x
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.2.1
Block Diagram
Figure 27-2. Cyclic Redundancy Check Block Diagram
Memory
(Boot, App,
Flash)
CTRLB
CTRLA
Source
Enable,
Reset
BUSY
CRC
calculation
STATUS
CRC OK
CHECKSUM
27.3
Functional Description
27.3.1
Initialization
NMI Req
To enable a CRC in software (or via the debugger):
1. Write the Source (SRC) bit field of the Control B register (CRCSCAN.CTRLB) to select the desired mode and
source settings.
2. Enable the CRCSCAN by writing a ‘1’ to the ENABLE bit in the Control A register (CRCSCAN.CTRLA).
3.
The CRC will start after three cycles. The CPU will continue executing during these three cycles.
The CRCSCAN can be configured to perform a code memory scan before the device leaves Reset. If this check fails,
the CPU is not allowed to start normal code execution. This feature is enabled and controlled by the CRCSRC field in
FUSE.SYSCFG0, see the Fuses chapter for more information.
If this feature is enabled, a successful CRC check will have the following outcome:
• Normal code execution starts
• The ENABLE bit in CRCSCAN.CTRLA will be ‘1’
•
•
The SRC bit field in CRCSCAN.CTRLB will reflect the checked section(s)
The OK flag in CRCSCAN.STATUS will be ‘1’
If this feature is enabled, a non-successful CRC check will have the following outcome:
• Normal code execution does not start, the CPU will hang executing no code
• The ENABLE bit in CRCSCAN.CTRLA will be ‘1’
27.3.2
•
•
The SRC bit field in CRCSCAN.CTRLB will reflect the checked section(s)
The OK flag in CRCSCAN.STATUS will be ‘0’
•
This condition may be observed using the debug interface
Operation
When the CRC is operating in Priority mode, the CRC peripheral has priority access to the Flash and will stall the
CPU until completed.
In Priority mode the CRC fetches a new word (16-bit) on every third main clock cycle, or when the CRC peripheral is
configured to do a scan from start-up.
27.3.2.1 Checksum
The pre-calculated checksum must be present in the last location of the section to be checked. If the BOOT section is
to be checked, the checksum must be saved in the last bytes of the BOOT section, and similarly for APPLICATION
and the entire Flash. Table 27-1 shows explicitly how the checksum must be stored for the different sections. Also,
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
see the CRCSCAN.CTRLB register description for how to configure which section to check and the device fuse
description for how to configure the BOOTEND and APPEND fuses.
Table 27-1. Placement of the Pre-Calculated Checksum in Flash
27.3.3
Section to Check
CHECKSUM[15:8]
CHECKSUM[7:0]
BOOT
FUSE_BOOTEND*256-2
FUSE_BOOTEND*256-1
BOOT and APPLICATION
FUSE_APPEND*256-2
FUSE_APPEND*256-1
Full Flash
FLASHEND-1
FLASHEND
Interrupts
Table 27-2. Available Interrupt Vectors and Sources
Name
Vector Description
Conditions
NMI
Non-Maskable Interrupt
CRC failure
When the interrupt condition occurs the OK flag in the Status (CRCSCAN.STATUS) register is cleared to ‘0’.
A Non-Maskable Interrupt (NMI) is enabled by writing a ‘1’ to the respective Enable (NMIEN) bit in the Control A
(CRCSCAN.CTRLA) register, but can only be disabled with a System Reset. An NMI is generated when the OK flag
in the CRCSCAN.STATUS register is cleared, and the NMIEN bit is ‘1’. The NMI request remains active until a
System Reset and cannot be disabled.
An NMI can be triggered even if interrupts are not globally enabled.
27.3.4
Sleep Mode Operation
CRCSCAN is halted in all Sleep modes. In all CPU Sleep modes, the CRCSCAN peripheral is halted and will resume
operation when the CPU wakes up.
The CRCSCAN starts operation three cycles after writing the EN bit in CRCSCAN.CTRLA. During these three cycles,
it is possible to enter Sleep mode. In this case:
1. The CRCSCAN will not start until the CPU is woken up.
2. Any interrupt handler will execute after CRCSCAN has finished.
27.3.5
Debug Operation
Whenever the debugger reads or writes a peripheral or memory location, the CRCSCAN will be disabled.
If the CRCSCAN is busy when the debugger accesses the device, the CRCSCAN will restart the ongoing operation
when the debugger accesses an internal register or when the debugger disconnects.
The BUSY bit in the Status (CRCSCAN.STATUS) register will read ‘1’ if the CRCSCAN was busy when the debugger
caused it to disable, but it will not actively check any section as long as the debugger keeps it disabled. There are
synchronized CRC status bits in the debugger's internal register space, which can be read by the debugger without
disabling the CRCSCAN. Reading the debugger's internal CRC status bits will make sure that the CRCSCAN is
enabled.
It is possible to write the CRCSCAN.STATUS register directly from the debugger:
• BUSY bit in CRCSCAN.STATUS:
– Writing the BUSY bit to ‘0’ will stop the ongoing CRC operation (so that the CRCSCAN does not restart its
operation when the debugger allows it).
– Writing the BUSY bit to ‘1’ will make the CRC start a single check with the settings in the Control B
(CRCSCAN.CTRLB) register, but not until the debugger allows it.
•
As long as the BUSY bit in CRCSCAN.STATUS is ‘1’, CRCSCAN.CTRLB and the Non-Maskable Interrupt
Enable (NMIEN) bit in the Control A (CRCSCAN.CTRLA) register cannot be altered.
OK bit in CRCSCAN.STATUS:
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
– Writing the OK bit to ‘0’ can trigger a Non-Maskable Interrupt (NMI) if the NMIEN bit in CRCSCAN.CTRLA
is ‘1’. If an NMI has been triggered, no writes to the CRCSCAN are allowed.
– Writing the OK bit to ‘1’ will make the OK bit read as ‘1’ when the BUSY bit in CRCSCAN.STATUS is ‘0’.
Writes to CRCSCAN.CTRLA and CRCSCAN.CTRLB from the debugger are treated in the same way as writes from
the CPU.
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.4
Register Summary - CRCSCAN
Offset
Name
Bit Pos.
7
0x00
0x01
0x02
CTRLA
CTRLB
STATUS
7:0
7:0
7:0
RESET
27.5
6
5
4
MODE[1:0]
3
2
1
0
NMIEN
ENABLE
SRC[1:0]
OK
BUSY
Register Description
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.5.1
Control A
Name:
Offset:
Reset:
Property:
CTRLA
0x00
0x00
-
If an NMI has been triggered this register is not writable.
Bit
Access
Reset
7
RESET
R/W
0
6
5
4
3
2
1
NMIEN
R/W
0
0
ENABLE
R/W
0
Bit 7 – RESET Reset CRCSCAN
Writing this bit to ‘1’ resets the CRCSCAN peripheral. The CRCSCAN Control registers and Status register
(CRCSCAN.CTRLA, CRCSCAN.CTRLB, CRCSCAN.STATUS) will be cleared one clock cycle after the RESET bit is
written to ‘1’.
If NMIEN is ‘0’, this bit is writable both when the CRCSCAN is busy (the BUSY bit in CRCSCAN.STATUS is ‘1’) and
not busy (the BUSY bit is ‘0’), and will take effect immediately.
If NMIEN is ‘1’, this bit is only writable when the CRCSCAN is not busy (the BUSY bit in CRCSCAN.STATUS is ‘0’).
The RESET bit is a strobe bit.
Bit 1 – NMIEN Enable NMI Trigger
When this bit is written to ‘1’, any CRC failure will trigger an NMI.
This bit can only be cleared by a system Reset - it is not cleared by a write to the RESET bit.
This bit can only be written to ‘1’ when the CRCSCAN is not busy (the BUSY bit in CRCSCAN.STATUS is ‘0’).
Bit 0 – ENABLE Enable CRCSCAN
Writing this bit to ‘1’ enables the CRCSCAN peripheral with the current settings. It will stay ‘1’ even after a CRC
check has completed, but writing it to ‘1’ again will start a new check.
Writing the bit to ‘0’ has no effect
The CRCSCAN can be configured to run a scan during the MCU start-up sequence to verify the Flash sections
before letting the CPU start normal code execution (see the 27.3.1 Initialization section). If this feature is enabled,
the ENABLE bit will read as ‘1’ when normal code execution starts.
To see whether the CRCSCAN peripheral is busy with an ongoing check, poll the BUSY bit in the Status register
(CRCSCAN.STATUS).
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.5.2
Control B
Name:
Offset:
Reset:
Property:
CTRLB
0x01
0x00
-
The CRCSCAN.CTRLB register contains the mode and source settings for the CRC. It is not writable when the CRC
is busy, or when an NMI has been triggered.
Bit
7
6
5
4
3
2
1
0
MODE[1:0]
Access
Reset
R/W
0
SRC[1:0]
R/W
0
R/W
0
R/W
0
Bits 5:4 – MODE[1:0] CRC Flash Access Mode
The CRC can be enabled during internal Reset initialization to verify Flash sections before letting the CPU start (see
the device data sheet fuse description). If the CRC is enabled during internal Reset initialization, the MODE bit field
will read out non-zero when normal code execution starts. To ensure proper operation of the CRC under code
execution, write the MODE bit to 0x0 again.
Value
Name
Description
0x0
PRIORITY The CRC module runs a single check with priority to Flash. The CPU is halted until the
CRC completes.
other
Reserved
Bits 1:0 – SRC[1:0] CRC Source
The SRC bit field selects which section of the Flash the CRC module will check. To set up section sizes, refer to the
fuse description.
The CRC can be enabled during internal Reset initialization to verify Flash sections before letting the CPU start (see
the Fuses chapter). If the CRC is enabled during internal Reset initialization, the SRC bit field will read out as FLASH,
BOOTAPP, or BOOT when normal code execution starts (depending on the configuration).
Value
Name
Description
0x0
FLASH
The CRC is performed on the entire Flash (boot, application code, and application data
sections).
0x1
BOOTAPP The CRC is performed on the boot and application code sections of Flash.
0x2
BOOT
The CRC is performed on the boot section of Flash.
0x3
Reserved.
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CRCSCAN - Cyclic Redundancy Check Memory Sca...
27.5.3
Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x02
0x02
-
6
5
4
3
Access
Reset
2
1
OK
R
1
0
BUSY
R
0
Bit 1 – OK CRC OK
When this bit is read as ‘1’, the previous CRC completed successfully. The bit is set to ‘1’ by default before a CRC
scan is run. The bit is not valid unless BUSY is ‘0’.
Bit 0 – BUSY CRC Busy
When this bit is read as ‘1’, the CRCSCAN is busy. As long as the module is busy, the access to the control registers
is limited.
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CCL - Configurable Custom Logic
28.
CCL - Configurable Custom Logic
28.1
Features
•
•
•
•
•
•
•
•
28.2
Glue Logic for General Purpose PCB Design
2 Programmable Look-Up Tables (LUTs)
Combinatorial Logic Functions: Any Logic Expression Which Is a Function of up to Three Inputs
Sequencer Logic Functions:
– Gated D flip-flop
– JK flip-flop
– Gated D latch
– RS latch
Flexible LUT Input Selection:
– I/Os
– Events
– Subsequent LUT output
– Internal peripherals such as:
• Analog comparator
• Timers/counters
• USART
• SPI
Clocked by a System Clock or Other Peripherals
Output Can Be Connected to I/O Pins or an Event System
Optional Synchronizer, Filter, or Edge Detector Available on Each LUT Output
Overview
The Configurable Custom Logic (CCL) is a programmable logic peripheral that can be connected to the device pins,
events or other internal peripherals. The CCL can serve as glue logic between the device peripherals and external
devices. The CCL can eliminate the need for external logic components and can also help the designer to overcome
real-time constraints by combining core independent peripherals to handle the most time-critical parts of the
application independent of the CPU.
The CCL peripheral provides several LUTs. Each LUT consists of three inputs, a truth table, a synchronizer/filter, and
an edge detector. Each LUT can generate an output as a user-programmable logic expression with three inputs. The
inputs can be individually masked.
The output is generated from the inputs using the combinatorial logic and can be filtered to remove spikes. Combine
neighboring LUTs to perform specific operations. Use a sequencer for generating complex waveforms.
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CCL - Configurable Custom Logic
28.2.1
Block Diagram
Figure 28-1. Configurable Custom Logic
Even LUT n
INSEL
Internal
Events
I/O
Peripherals
FILTSEL
LUTn-TRUTHSEL[2:0]
TRUTH
Filter/
Synch
CLKSRC
EDGEDET
Edge
Detector
LUTn-OUT
CLK_MUX_OUTn
LUTn-TRUTHSEL[2]
clkCCL
SEQSEL
Sequential
ENABLE
Odd LUT n+1
INSEL
Internal
Events
I/O
Peripherals
TRUTH
Filter/
Synch
CLKSRC
LUTn+1-TRUTHSEL[2]
clkCCL
FILTSEL
LUTn+1-TRUTHSEL[2:0]
EDGEDET
Edge
Detector
LUTn+1-OUT
CLK_MUX_OUTn+1
ENABLE
28.2.2
Signal Description
Pin Name
Type
Description
LUTn-OUT
Digital output
Output from LUT
LUTn-IN[2:0]
Digital input
Input to LUT
Refer to I/O Multiplexing and Considerations for details on the pin mapping for this peripheral. One signal can be
mapped to several pins.
28.2.3
System Dependencies
To use this peripheral, other parts of the system must be configured correctly, as described below.
Table 28-1. CCL System Dependencies
Dependency
Applicable
Peripheral
Clocks
Yes
CLKCTRL
I/O Lines and Connections
Yes
PORT
Interrupts
No
-
Events
Yes
EVSYS
Debug
Yes
UPDI
28.2.3.1 Clocks
The filter, edge detector, and sequencer are, by default, clocked by the peripheral clock (CLK_PER). It is also
possible to use other clock inputs (CLK_MUX_OUTn) to clock these blocks. This is configured by writing the Clock
Source Selection (CLKSRC) bit field in the LUT Control A register.
When the Clock Source Selection (CLKSRC) bit is written to ‘1’, LUTn-TRUTHSEL[2] is used to clock the
corresponding filter and edge detector (CLK_MUX_OUTn). The sequencer is clocked by the CLK_MUX_OUTn of the
even LUT in the pair. When CLKSRC is written to ‘1’, LUTn-TRUTHSEL[2] is treated as OFF (low) in the truth table.
The CCL peripheral must be disabled while changing the clock source to avoid undefined outputs from the peripheral.
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CCL - Configurable Custom Logic
28.2.3.2 I/O Lines
The CCL can take inputs and generate output through I/O pins. For this to function correctly, configure the I/O pins to
be used by an LUT.
28.2.3.3 Interrupts
Not applicable.
28.2.3.4 Debug Operation
When the CPU is halted in Debug mode, the CCL continues normal operation. However, the CCL cannot be halted
when the CPU is halted in Debug mode. If the CCL is configured in a way that requires it to be periodically serviced
by the CPU, improper operation or data loss may result during debugging.
28.3
Functional Description
28.3.1
Initialization
The configuration of the LUTs and sequencers is enable-protected, meaning that they can only be configured when
the corresponding even LUT is disabled (ENABLE = ‘0’ in the LUT n Control A (CCL.LUTnCTRLA) register). This is a
mechanism to suppress the undesired output from the CCL under (re-)configuration.
The following bits and registers are enable-protected:
•
•
The Sequencer Selection (SEQSEL) bits in the Sequencer Control n (CCL.SEQCTRLn) register
The LUT n Control x (CCL.LUTnCTRLx) registers, except the ENABLE bit in the CCL.LUTnCTRLA register
The enable-protected bits in the CCL.LUTnCTRLx registers can be written at the same time as the ENABLE bit in the
CCL.LUTnCTRLA register is written to ‘1’, but not at the same time as the ENABLE bit is written to ‘0’.
The enable protection is denoted by the enable-protected property in the register description.
28.3.2
Operation
28.3.2.1 Enabling, Disabling, and Resetting
The CCL is enabled by writing a ‘1’ to the ENABLE bit in the Control A (CCL.CTRLA) register. The CCL is disabled
by writing a ‘0’ to that ENABLE bit.
Each LUT is enabled by writing a ‘1’ to the LUT Enable (ENABLE) bit in the CCL.LUTnCTRLA register. Each LUT is
disabled by writing a ‘0’ to the ENABLE bit in the CCL.LUTnCTRLA register.
28.3.2.2 Truth Table Logic
The truth table in each LUT unit can generate a combinational logic output as a function of up to three inputs (LUTnTRUTHSEL[2:0]). It is possible to realize any 3-input Boolean logic function using one LUT.
Figure 28-2. Truth Table Output Value Selection of an LUT
TRUTHn[0]
TRUTHn[1]
TRUTHn[2]
TRUTHn[3]
TRUTHn[4]
TRUTHn[5]
TRUTHn[6]
TRUTHn[7]
OUT
LUTn-TRUTHSEL[2:0]
Configure the truth table inputs (LUTn-TRUTHSEL[2:0]) by writing the Input Source Selection bit fields in the LUT
Control registers:
• INSEL0 in CCL.LUTnCTRLB
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CCL - Configurable Custom Logic
•
•
INSEL1 in CCL.LUTnCTRLB
INSEL2 in CCL.LUTnCTRLC
Each combination of the input bits (LUTn-TRUTHSEL[2:0]) corresponds to one bit in the CCL.TRUTHn register, as
shown in the table below:
Table 28-2. Truth Table of an LUT
LUTn-TRUTHSEL[2]
LUTn-TRUTHSEL[1]
LUTn-TRUTHSEL[0]
OUT
0
0
0
TRUTHn[0]
0
0
1
TRUTHn[1]
0
1
0
TRUTHn[2]
0
1
1
TRUTHn[3]
1
0
0
TRUTHn[4]
1
0
1
TRUTHn[5]
1
1
0
TRUTHn[6]
1
1
1
TRUTHn[7]
Important: Consider the unused inputs turned off (tied low) when logic functions are created.
Example 28-1. LUT Output for CCL.TRUTHn = 0x42
If CCL.TRUTHn is configured to 0x42, the LUT output will be 1 when the inputs are ‘b001 or
‘b110 and 0 for any other combination of inputs.
28.3.2.3 Truth Table Inputs Selection
Input Overview
The inputs can be individually:
•
•
•
•
Masked
Driven by Peripherals:
– Analog Comparator (AC) output
– Timer/Counters (TC) waveform outputs
Driven by Internal Events from Event System
Driven by Other CCL Submodules
Internal Feedback Inputs (FEEDBACK)
When selected (INSELy = FEEDBACK in CCL.LUTnCTRLx), the Sequencer (SEQ) output is used as input for the
corresponding LUT.
The output from an internal sequencer can be used as an input source for the LUT. See the figure below for an
example for LUT0 and LUT1. The sequential selection for each LUT follows the formula:
IN 2N � = SEQ �
IN 2N+1 � = SEQ �
With N representing the sequencer number, and i = 0, 1, 2 representing the LUT input index.
For more details, refer to 28.3.2.6 Sequencer Logic.
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CCL - Configurable Custom Logic
Figure 28-3. Feedback Input Selection
Linked LUT (LINK)
When selecting the LINK input option, the next LUT’s direct output is used as the LUT input. In general, LUT[n+1] is
linked to the input of LUT[n]. LUT0 is linked to the input of the last LUT.
Figure 28-4. Linked LUT Input Selection
LUT0
SEQ 0
CTRL
(ENABLE)
LUT1
Internal Events Inputs Selection (EVENT)
Asynchronous events from the Event System can be used as input to the LUT. Two event input lines (EVENT0 and
EVENT1) are available and can be selected as LUT input. Configure the Event System before selecting the EVENT
input option.
I/O Pin Inputs (I/O)
When selecting the I/O option, the LUT input will be connected to its corresponding I/O pin. Refer to the I/O
Multiplexing section for more details about where the LUTnINy is located.
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Figure 28-5. I/O Pin Input Selection
I/O
Peripherals
The different peripherals on the three input lines of each LUT are selected by writing to the respective LUT n Input y
bit fields in the LUT n Control B and C registers:
• INSEL0 in CCL.LUTnCTRLB
• INSEL1 in CCL.LUTnCTRLB
• INSEL2 in CCL.LUTnCTRLC
28.3.2.4 Filter
By default, the LUT output is a combinational function of the LUT inputs. This may cause some short glitches when
the inputs change the value. These glitches can be removed by clocking through filters if demanded by application
needs.
The Filter Selection (FILTSEL) bits in the LUT n Control A (CCL.LUTnCTRLA) registers define the digital filter
options.
When FILTSEL = SYNCH, the output is synchronized with CLK_MUX_OUTn. The output will be delayed by two
positive CLK_MUX_OUTn edges.
When FILTSEL = FILTER, only the input that is persistent for more than two positive CLK_MUX_OUTn edges will
pass through the gated flip-flop to the output. The output will be delayed by four positive CLK_MUX_OUTn edges.
One clock cycle later, after the corresponding LUT is disabled, all internal filter logic is cleared.
Figure 28-6. Filter
FILTSEL
Input
OUT
Q
D
R
Q
D
R
Q
D
R
D
G
Q
R
CLK_MUX_OUT
CLR
28.3.2.5 Edge Detector
Use the edge detector to generate a pulse when detecting a rising edge on its input. Program the truth table to
provide an inverted output to detect a falling edge.
The edge detector is enabled by writing a ‘1’ to the Edge Selection (EDGEDET) bit in the CCL.LUTnCTRLA register.
To avoid unpredictable behavior, a valid filter option must be enabled as well.
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CCL - Configurable Custom Logic
The edge detection is disabled by writing a ‘0’ to the EDGEDET bit in the CCL.LUTnCTRLA register. After disabling
an LUT, the corresponding internal edge detector logic is cleared one clock cycle later.
Figure 28-7. Edge Detector
EDGEDET
CLK_MUX_OUTn
28.3.2.6 Sequencer Logic
Each LUT pair can be connected to a sequencer. The sequencer can function as either D flip-flop, JK flip-flop, gated
D latch, or RS latch. The function is selected by writing the Sequencer Selection (SEQSEL) bit field in the Sequencer
Control (CCL.SEQCTRLn) register.
The sequencer receives its input from either the LUT, filter or edge detector, depending on the configuration.
A sequencer is clocked by the same clock as the corresponding even LUT. The clock source is selected by the Clock
Source (CLKSRC) bit field in the CCL.LUTnCTRLA register.
The flip-flop output (OUT) is refreshed on the rising edge of the clock. When the even LUT is disabled, the latch is
cleared asynchronously. The flip-flop Reset signal (R) is kept enabled for one clock cycle.
Gated D Flip-Flop (DFF)
The D input is driven by the even LUT output, and the G input is driven by the odd LUT output.
Figure 28-8. D Flip-Flop
even LUT
CLK_MUX_OUT
odd LUT
Table 28-3. DFF Characteristics
R
G
D
OUT
1
X
X
Clear
0
1
1
Set
0
Clear
X
Hold state (no change)
0
JK Flip-Flop (JK)
The J input is driven by the even LUT output, and the K input is driven by the odd LUT output.
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Figure 28-9. JK Flip-Flop
even LUT
CLK_MUX_OUT
odd LUT
Table 28-4. JK Characteristics
R
J
K
OUT
1
X
X
Clear
0
0
0
Hold state (no change)
0
0
1
Clear
0
1
0
Set
0
1
1
Toggle
Gated D Latch (DLATCH)
The D input is driven by the even LUT output, and the G input is driven by the odd LUT output.
Figure 28-10. D Latch
even LUT
D
odd LUT
G
Q
OUT
Table 28-5. D Latch Characteristics
G
D
OUT
0
X
Hold state (no change)
1
0
Clear
1
1
Set
RS Latch (RS)
The S input is driven by the even LUT output, and the R input is driven by the odd LUT output.
Figure 28-11. RS Latch
even LUT
S
odd LUT
R
Q
OUT
Table 28-6. RS Latch Characteristics
S
R
OUT
0
0
Hold state (no change)
0
1
Clear
1
0
Set
1
1
Forbidden state
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CCL - Configurable Custom Logic
28.3.2.7 Clock Source Settings
The filter, edge detector, and sequencer are, by default, clocked by the peripheral clock (CLK_PER). It is also
possible to use other clock inputs (CLK_MUX_OUTn) to clock these blocks. Configure this by writing the CLKSRC bit
in the LUT Control A register.
Figure 28-12. Clock Source Settings
Filter
Edge
Detector
LUTn-TRUTHSEL[2]
CLK_MUX_OUTn
CLK_CCL
CLKSRC
LUTn
Sequential
logic
When the CLKSRC bit is written to 0x1, LUTn-TRUTHSEL[2] is used to clock the corresponding filter and
edge
detector (CLK_MUX_OUTn). The sequencer is clocked by the CLK_MUX_OUTn of the even LUT in the pair. When
CLKSRC is written to 0x1, LUTn-TRUTHSEL[2] is treated as OFF (low) in the truth table.
Filter
Edge
The CCL peripheral must
be disabled while changing the clock sourceDetector
to avoid undetermined outputs from the
LUTn+1-TRUTHSEL[2]
peripheral.
28.3.3
Events
CLK_MUX_OUTn+1
The CCL can generate the following output event:
•
LUTnOUT: Look-up Table Output Value
CLK_CCL
The CCL can take the following actions on an input event:
•
28.3.4
INx: The event is used as input for the truth table
CLKSRC
Sleep Mode Operation
LUTn+1
Writing the Run In Standby (RUNSTDBY) bit in the CCL.CTRLA register to ‘1’ will allow the selected clock source to
be enabled in Standby sleep mode.
If RUNSTDBY is ‘0’, the peripheral clock will be disabled in Standby sleep mode. If the filter, edge detector, and/or
sequencer are enabled, the LUT output will be forced to ‘0’ in Standby sleep mode. In Idle sleep mode, the truth table
decoder will continue the operation, and the LUT output will be refreshed accordingly, regardless of the RUNSTDBY
bit.
If the CLKSRC bit in the CCL.LUTnCTRLA register is written to ‘1’, the LUTn-TRUTHSEL[2] will always clock the
filter, edge detector, and Sequencer block. The availability of the LUTn-TRUTHSEL[2] clock in sleep modes will
depend on the sleep settings of the peripheral used.
28.3.5
Configuration Change Protection
Not applicable.
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ATtiny212/214/412/414/416
CCL - Configurable Custom Logic
28.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
...
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
CTRLA
SEQCTRL0
7:0
7:0
28.5
7
6
5
4
3
2
1
RUNSTDBY
0
ENABLE
SEQSEL0[3:0]
Reserved
LUT0CTRLA
LUT0CTRLB
LUT0CTRLC
TRUTH0
LUT1CTRLA
LUT1CTRLB
LUT1CTRLC
TRUTH1
7:0
7:0
7:0
7:0
7:0
7:0
7:0
7:0
EDGEDET
EDGEDET
CLKSRC
INSEL1[3:0]
FILTSEL[1:0]
CLKSRC
INSEL1[3:0]
FILTSEL[1:0]
OUTEN
ENABLE
INSEL0[3:0]
INSEL2[3:0]
TRUTH0[7:0]
OUTEN
ENABLE
INSEL0[3:0]
INSEL2[3:0]
TRUTH1[7:0]
Register Description
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CCL - Configurable Custom Logic
28.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
CTRLA
0x00
0x00
-
6
RUNSTDBY
R/W
0
5
4
3
2
1
0
ENABLE
R/W
0
Bit 6 – RUNSTDBY Run in Standby
This bit indicates if the peripheral clock (CLK_PER) is kept running in Standby sleep mode. The setting is ignored for
configurations where the CLK_PER is not required.
Value
Description
0
System clock is not required in Standby sleep mode
1
System clock is required in Standby sleep mode
Bit 0 – ENABLE Enable
Value
Description
0
The peripheral is disabled
1
The peripheral is enabled
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CCL - Configurable Custom Logic
28.5.2
Sequencer Control 0
Name:
Offset:
Reset:
Property:
Bit
7
SEQCTRL0
0x01
0x00
Enable-Protected
6
Access
Reset
5
4
3
R/W
0
2
1
SEQSEL0[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 3:0 – SEQSEL0[3:0] Sequencer Selection
This bit field selects the sequencer configuration for LUT0 and LUT1.
Value
Name
Description
0x0
DISABLE
Sequencer logic is disabled
0x1
DFF
D flip-flop
0x2
JK
JK flip-flop
0x3
LATCH
D latch
0x4
RS
RS latch
Other
Reserved
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CCL - Configurable Custom Logic
28.5.3
LUT n Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
EDGEDET
R/W
0
LUTnCTRLA
0x05 + n*0x04 [n=0..1]
0x00
Enable-Protected
6
CLKSRC
R/W
0
5
4
FILTSEL[1:0]
R/W
R/W
0
0
3
OUTEN
R/W
0
2
1
0
ENABLE
R/W
0
Bit 7 – EDGEDET Edge Detection
Value
Description
0
Edge detector is disabled
1
Edge detector is enabled
Bit 6 – CLKSRC Clock Source Selection
This bit selects whether the peripheral clock (CLK_PER) or any source selected by the INSEL2 bit field of the
LUTnCTRLC register (LUTn-TRUTHSEL[2]) is used as the clock (CLK_MUX_OUTn) for an LUT.
The CLK_MUX_OUTn of the even LUT is used for clocking the Sequencer block of an LUT pair.
Value
Description
0
CLK_PER is clocking the LUTn
1
LUTn-TRUTHSEL[2] is clocking the LUTn
Bits 5:4 – FILTSEL[1:0] Filter Selection
This bit field selects the LUT output filter options.
Value
Name
Description
0x0
DISABLE
Filter disabled
0x1
SYNCH
Synchronizer enabled
0x2
FILTER
Filter enabled
0x3
Reserved
Bit 3 – OUTEN Output Enable
This bit enables the LUT output to the LUTnOUT pin. When written to ‘1’, the pin configuration of the PORT I/O
Controller is overridden.
Value
Description
0
Output to pin disabled
1
Output to pin enabled
Bit 0 – ENABLE LUT Enable
Value
Description
0
The LUT is disabled
1
The LUT is enabled
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CCL - Configurable Custom Logic
28.5.4
LUT n Control B
Name:
Offset:
Reset:
Property:
LUTnCTRLB
0x06 + n*0x04 [n=0..1]
0x00
Enable-Protected
Notes:
1. SPI connections to the CCL work in Host SPI mode only.
2. USART connections to the CCL work only when the USART is in one of the following modes:
– Asynchronous USART
– Synchronous USART Host
Bit
Access
Reset
7
6
5
INSEL1[3:0]
R/W
R/W
0
0
R/W
0
4
3
R/W
0
R/W
0
2
1
INSEL0[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 7:4 – INSEL1[3:0] LUT n Input 1 Source Selection
This bit field selects the source for input 1 of LUT n.
Value
Name
Description
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
Other
MASK
FEEDBACK
LINK
EVENT0
EVENT1
IO
AC0
TCB0
TCA0
TCD0
USART0
SPI0
-
Masked input
Feedback input
Linked other LUT as input source
Event input source 0
Event input source 1
I/O-pin LUTn-IN1 input source
AC0 OUT input source
TCB0 WO input source
TCA0 WO1 input source
TCD0 WOB input source
USART0 TXD input source
SPI0 MOSI input source
Reserved
Bits 3:0 – INSEL0[3:0] LUT n Input 0 Source Selection
This bit field selects the source for input 0 of LUT n.
Value
Name
Description
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
Other
MASK
FEEDBACK
LINK
EVENT0
EVENT1
IO
AC0
TCB0
TCA0
TCD0
USART0
SPI0
-
Masked input
Feedback input
Linked other LUT as input source
Event input source 0
Event input source 1
I/O-pin LUTn-IN0 input source
AC0 OUT input source
TCB0 WO input source
TCA0 WO0 input source
TCD0 WOA input source
USART0 XCK input source
SPI0 SCK input source
Reserved
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CCL - Configurable Custom Logic
28.5.5
LUT n Control C
Name:
Offset:
Reset:
Property:
Bit
LUTnCTRLC
0x07 + n*0x04 [n=0..1]
0x00
Enable-Protected
7
6
5
4
Access
Reset
3
R/W
0
2
1
INSEL2[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 3:0 – INSEL2[3:0] LUT n Input 2 Source Selection
This bit field selects the source for input 2 of LUT n.
Value
Name
Description
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
Other
MASK
FEEDBACK
LINK
EVENT0
EVENT1
IO
AC0
TCB0
TCA0
TCD0
SPI0
-
Masked input
Feedback input
Linked other LUT as input source
Event input source 0
Event input source 1
I/O-pin LUTn-IN2 input source
AC0 OUT input source
TCB0 WO input source
TCA0 WO2 input source
TCD0 WOA input source
Reserved
SPI0 MISO input source
Reserved
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CCL - Configurable Custom Logic
28.5.6
TRUTHn
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
TRUTHn
0x08 + n*0x04 [n=0..1]
0x00
Enable-Protected
7
6
5
R/W
0
R/W
0
R/W
0
4
3
TRUTHn[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TRUTHn[7:0] Truth Table
These bits determine the output of LUTn according to the LUTn-TRUTHSEL[2:0] inputs.
Bit Name
TRUTHn[0]
TRUTHn[1]
TRUTHn[2]
TRUTHn[3]
TRUTHn[4]
TRUTHn[5]
TRUTHn[6]
TRUTHn[7]
Value
Description
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
The output of LUTn is 0 when the inputs are ‘b000
The output of LUTn is 1 when the inputs are ‘b000
The output of LUTn is 0 when the inputs are ‘b001
The output of LUTn is 1 when the inputs are ‘b001
The output of LUTn is 0 when the inputs are ‘b010
The output of LUTn is 1 when the inputs are ‘b010
The output of LUTn is 0 when the inputs are ‘b011
The output of LUTn is 1 when the inputs are ‘b011
The output of LUTn is 0 when the inputs are ‘b100
The output of LUTn is 1 when the inputs are ‘b100
The output of LUTn is 0 when the inputs are ‘b101
The output of LUTn is 1 when the inputs are ‘b101
The output of LUTn is 0 when the inputs are ‘b110
The output of LUTn is 1 when the inputs are ‘b110
The output of LUTn is 0 when the inputs are ‘b111
The output of LUTn is 1 when the inputs are ‘b111
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AC - Analog Comparator
29.
AC - Analog Comparator
29.1
Features
•
•
•
•
•
•
•
•
29.2
50 ns Response Time for Supply Voltage Above 2.7V
Zero-Cross Detection
Selectable Hysteresis:
– None
– 10 mV
– 25 mV
– 50 mV
Analog Comparator Output Available on Pin
Comparator Output Inversion Available
Flexible Input Selection:
– Up to two positive pins
– Up to two negative pins
– Output from the DAC
– Internal reference voltage
Interrupt Generation On:
– Rising edge
– Falling edge
– Both edges
Event Generation:
– Comparator output
Overview
The Analog Comparator (AC) compares the voltage levels on two inputs and gives a digital output based on this
comparison. The AC can be configured to generate interrupt requests and/or events upon several different
combinations of input change.
The dynamic behavior of the AC can be adjusted by a hysteresis feature. The hysteresis can be customized to
optimize the operation for each application.
The input selection includes analog port pins, DAC output and internal reference voltage. The analog comparator
output state can also be output on a pin for use by external devices.
An AC has one positive input and one negative input. The positive input source is one of the analog input pins. The
negative input is chosen either from analog input pins or from internal inputs, such as an internal voltage reference.
The digital output from the comparator is ‘1’ when the difference between the positive and the negative input voltage
is positive, and ‘0’ otherwise.
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AC - Analog Comparator
29.2.1
Block Diagram
Figure 29-1. Analog Comparator
Note: Refer to 29.1 Features for the number of AINN and AINP.
29.2.2
29.2.3
Signal Description
Signal
Description
Type
AINNn
Negative Input n
Analog
AINPn
Positive Input n
Analog
OUT
Comparator Output for AC
Digital
System Dependencies
To use this peripheral, other parts of the system must be configured correctly, as described below.
Table 29-1. AC System Dependencies
Dependency
Applicable
Peripheral
Clocks
Yes
CLKCTRL
I/O Lines and Connections
Yes
PORT
Interrupts
Yes
CPUINT
Events
Yes
EVSYS
Debug
Yes
UPDI
29.2.3.1 Clocks
This peripheral depends on the peripheral clock.
29.2.3.2 I/O Lines and Connections
The I/O pins AINNn and AINPn are all analog inputs to the AC.
For correct operation, the pins must be configured in the port and port multiplexing peripherals.
It is recommended to disable the GPIO input when using the AC.
29.2.3.3 Interrupts
Using the interrupts of this peripheral requires the interrupt controller to be configured first.
29.2.3.4 Events
The events of this peripheral are connected to the Event System.
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AC - Analog Comparator
29.2.3.5 Debug Operation
This peripheral is unaffected by entering Debug mode.
If the peripheral is configured to require periodic service by the CPU through interrupts or similar, improper operation
or data loss may result during halted debugging.
29.3
Functional Description
29.3.1
Initialization
For basic operation, follow these steps:
1. Configure the desired input pins in the port peripheral.
2. Select the positive and negative input sources by writing the Positive and Negative Input MUX Selection
(MUXPOS and MUXNEG) bit fields in the MUX Control A (ACn.MUXCTRLA) register.
3. Optional: Enable the output to pin by writing a ‘1’ to the Output Pad Enable (OUTEN) bit in the Control A
(ACn.CTRLA) register.
4. Enable the AC by writing a ‘1’ to the ENABLE bit in the ACn.CTRLA register.
During the start-up time after enabling the AC, the output of the AC may be invalid.
The start-up time of the AC by itself is at most 2.5 µs. If an internal reference is used, the reference start-up time is
normally longer than the AC start-up time. The VREF start-up time is 60 µs at most.
29.3.2
Operation
29.3.2.1 Input Hysteresis
Applying an input hysteresis helps to prevent constant toggling of the output when the noise-afflicted input signals are
close to each other.
The input hysteresis can either be disabled or have one of three levels. The hysteresis is configured by writing to the
Hysteresis Mode Select (HYSMODE) bit field in the Control A (ACn.CTRLA) register.
29.3.2.2 Input Sources
An AC has one positive input and one negative input. The inputs can be pins and internal sources, such as a voltage
reference.
Each input is selected by writing to the Positive and Negative Input MUX Selection (MUXPOS and MUXNEG) bit field
in the MUX Control A (ACn.MUXCTRLA) register.
29.3.2.2.1 Pin Inputs
The following analog input pins on the port can be selected as input to the analog comparator:
•
•
•
•
AINN0
AINN1(1)
AINP0
AINP1(1)
Note:
1. Not all pins of a port are available on devices with low pin counts. Check the Pinout Diagram and/or the I/O
Multiplexing table for details.
29.3.2.2.2 Internal Inputs
The AC has the following internal inputs:
•
•
Output from DAC
AC voltage reference
29.3.2.3 Low-Power Mode
For power sensitive applications, the AC provides a Low-Power mode with reduced power consumption and
increased propagation delay.
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AC - Analog Comparator
This mode is enabled by writing a ‘1’ to the Low-Power Mode (LPMODE) bit in the Control A (ACn.CTRLA) register.
29.3.3
Events
The AC will generate the following event automatically when the AC is enabled:
•
The digital output from the AC (OUT in the block diagram) is available as an Event System source. The events
from the AC are asynchronous to any clocks in the device.
The AC has no event inputs.
29.3.4
Interrupts
Table 29-2. Available Interrupt Vectors and Sources
Offset Name
0x00
Vector Description
COMP0 Analog comparator interrupt
Conditions
AC output is toggling as configured by INTMODE in ACn.CTRLA
When an Interrupt condition occurs, the corresponding Interrupt flag is set in the STATUS (ACn.STATUS) register.
An interrupt source is enabled or disabled by writing to the corresponding bit in the peripheral’s Interrupt Control
(ACn.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled and the Interrupt flag is set.
The interrupt request remains active until the Interrupt flag is cleared. See the ACn.STATUS register description for
details on how to clear Interrupt flags.
29.3.5
Sleep Mode Operation
In Idle sleep mode, the AC will continue to operate as normal.
In Standby sleep mode, the AC is disabled by default. If the Run in Standby Mode (RUNSTDBY) bit in the Control A
(ACn.CTRLA) register is written to ‘1’, the AC will continue to operate, but the Status register will not be updated, and
no interrupts are generated if no other modules request the CLK_PER, but events and the pad output will be
updated.
In Power-Down sleep mode, the AC and the output to the pad are disabled.
29.3.6
Configuration Change Protection
Not applicable.
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AC - Analog Comparator
29.4
Register Summary
Offset
Name
Bit Pos.
7
6
0x00
0x01
0x02
0x03
...
0x05
0x06
0x07
CTRLA
Reserved
MUXCTRLA
7:0
RUNSTDBY
OUTEN
7:0
INVERT
29.5
5
4
INTMODE[1:0]
3
LPMODE
MUXPOS[1:0]
2
1
HYSMODE[1:0]
0
ENABLE
MUXNEG[1:0]
Reserved
INTCTRL
STATUS
7:0
7:0
STATE
CMP
CMP
Register Description
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AC - Analog Comparator
29.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RUNSTDBY
R/W
0
CTRLA
0x00
0x00
-
6
OUTEN
R/W
0
5
4
INTMODE[1:0]
R/W
R/W
0
0
3
LPMODE
R/W
0
2
1
HYSMODE[1:0]
R/W
R/W
0
0
0
ENABLE
R/W
0
Bit 7 – RUNSTDBY Run in Standby Mode
Writing a ‘1’ to this bit allows the AC to continue operation in Standby sleep mode. Since the clock is stopped,
interrupts and status flags are not updated.
Value
Description
0
In Standby sleep mode, the peripheral is halted
1
In Standby sleep mode, the peripheral continues operation
Bit 6 – OUTEN Analog Comparator Output Pad Enable
Writing this bit to ‘1’ makes the OUT signal available on the pin.
Bits 5:4 – INTMODE[1:0] Interrupt Modes
Writing to this bit field selects what edges of the AC output triggers an interrupt request.
Value
Name
Description
0x0
BOTHEDGE
Both negative and positive edge
0x1
Reserved
0x2
NEGEDGE
Negative edge
0x3
POSEDGE
Positive edge
Bit 3 – LPMODE Low-Power Mode
Writing a ‘1’ to this bit reduces the current through the comparator. This reduces the power consumption but
increases the reaction time of the AC.
Value
Description
0
Low-Power mode disabled
1
Low-Power mode enabled
Bits 2:1 – HYSMODE[1:0] Hysteresis Mode Select
Writing to this bit field selects the Hysteresis mode for the AC input.
Value
Name
Description
0x0
OFF
OFF
0x1
10
±10 mV
0x2
25
±25 mV
0x3
50
±50 mV
Bit 0 – ENABLE Enable AC
Writing this bit to ‘1’ enables the AC.
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29.5.2
MUX Control A
Name:
Offset:
Reset:
Property:
MUXCTRLA
0x02
0x00
-
ACn.MUXCTRLA controls the analog comparator MUXes.
Bit
Access
Reset
7
INVERT
R/W
0
6
5
4
3
MUXPOS[1:0]
R/W
R/W
0
0
2
1
0
MUXNEG[1:0]
R/W
R/W
0
0
Bit 7 – INVERT Invert AC Output
Writing a ‘1’ to this bit enables inversion of the output of the AC. This effectively inverts the input to all the peripherals
connected to the signal and affects the internal status signals.
Bits 4:3 – MUXPOS[1:0] Positive Input MUX Selection
Writing to this bit field selects the input signal to the positive input of the AC.
Value
Name
Description
0x0
0x0
Other
AINP0
AINP1(1)
-
Positive pin 0
Positive pin 1
Reserved
Note:
1. Not all pins of a port are available on devices with low pin counts. Check the Pinout Diagram and/or the I/O
Multiplexing table for details.
Bits 1:0 – MUXNEG[1:0] Negative Input MUX Selection
Writing to this bit field selects the input signal to the negative input of the AC.
Value
Name
Description
0x0
0x1
0x2
0x3
AINN0
AINN1(1)
VREF
DAC
Negative pin 0
Negative pin 1
Voltage Reference
DAC output
Note:
1. Not all pins of a port are available on devices with low pin counts. Check the Pinout Diagram and/or the I/O
Multiplexing table for details.
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AC - Analog Comparator
29.5.3
Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x06
0x00
-
6
5
4
3
Access
Reset
2
1
0
CMP
R/W
0
Bit 0 – CMP Analog Comparator Interrupt Enable
Writing this bit to ‘1’ enables analog comparator interrupt.
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29.5.4
Status
Name:
Offset:
Reset:
Property:
Bit
7
STATUS
0x07
0x00
-
6
Access
Reset
5
4
STATE
R
0
3
2
1
0
CMP
R/W
0
Bit 4 – STATE Analog Comparator State
This shows the current status of the OUT signal from the AC. This will have a synchronizer delay to get updated in
the I/O register (three cycles).
Bit 0 – CMP Analog Comparator Interrupt Flag
This is the Interrupt flag for AC. Writing a ‘1’ to this bit will clear the Interrupt flag.
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ADC - Analog-to-Digital Converter
30.
ADC - Analog-to-Digital Converter
30.1
Features
•
•
•
•
•
•
•
•
•
•
•
30.2
10-Bit Resolution
0V to VDD Input Voltage Range
Multiple Internal ADC Reference Voltages
External Reference Input
Free-Running and Single Conversion Mode
Interrupt Available on Conversion Complete
Optional Interrupt on Conversion Results
Temperature Sensor Input Channel
Optional Event-Triggered Conversion
Window Comparator Function for Accurate Monitoring or Defined Thresholds
Accumulation up to 64 Samples per Conversion
Overview
The Analog-to-Digital Converter (ADC) peripheral produces 10-bit results. The ADC input can either be internal (e.g.,
a voltage reference) or external through the analog input pins. The ADC is connected to an analog multiplexer, which
allows the selection of multiple single-ended voltage inputs. The single-ended voltage inputs refer to 0V (GND).
The ADC supports sampling in bursts where a configurable number of conversion results are accumulated into a
single ADC result (Sample Accumulation). Further, a sample delay can be configured to tune the ADC sampling
frequency associated with a single burst. This is to tune the sampling frequency away from any harmonic noise
aliased with the ADC sampling frequency (within the burst) from the sampled signal. An automatic sampling delay
variation feature can be used to randomize this delay to slightly change the time between samples.
The ADC input signal is fed through a sample-and-hold circuit that ensures that the input voltage to the ADC is held
at a constant level during sampling.
The selectable voltage references from the internal Voltage Reference (VREF) peripheral, are VDD supply voltage, or
external VREF pin (VREFA).
A window compare feature is available for monitoring the input signal and can be configured to only trigger an
interrupt on user-defined thresholds for under, over, inside, or outside a window, with minimum software intervention
required.
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30.2.1
Block Diagram
Figure 30-1. ADC Block Diagram
Internal reference
..
.
ADC
‘enable’
VREF
TEMPSENSE
RES
‘accumulate’
DAC
‘convert’
AINn
VDD
‘sample’
AIN0
AIN1
VREF
>
<
WCMP
(IRQ)
Control Logic
MUXPOS
CTRLA
EVCTRL
COMMAND
RESRDY
(IRQ)
WINLT
WINHT
The analog input channel is selected by writing to the MUXPOS bits in the MUXPOS (ADCn.MUXPOS) register. Any
of the ADC input pins, GND, internal Voltage Reference (VREF), or temperature sensor, can be selected as a singleended input to the ADC. The ADC is enabled by writing a ‘1’ to the ADC ENABLE bit in the Control A (ADCn.CTRLA)
register. The voltage reference and input channel selections will not go into effect before the ADC is enabled. The
ADC does not consume power when the ENABLE bit in ADCn.CTRLA is ‘0’.
The ADC generates a 10-bit result that can be read from the Result (ADCn.RES) Register. The result is presented
right-adjusted.
30.2.2
Signal Description
Pin Name
Type
Description
AIN[n:0]
Analog input
Analog input pin
VREFA
Analog input
External voltage reference pin
30.3
Functional Description
30.3.1
Initialization
The following steps are recommended to initialize the ADC operation:
1. Configure the resolution by writing to the Resolution Selection (RESSEL) bit in the Control A (ADCn.CTRLA)
register.
2. Optional: Enable the Free-Running mode by writing a ‘1’ to the Free-Running (FREERUN) bit in
ADCn.CTRLA.
3. Optional: Configure the number of samples to be accumulated per conversion by writing the Sample
Accumulation Number Select (SAMPNUM) bits in the Control B (ADCn.CTRLB) register.
4. Configure a voltage reference by writing to the Reference Selection (REFSEL) bit in the Control C
(ADCn.CTRLC) register. The default is the internal voltage reference of the device (VREF, as configured there).
5. Configure the CLK_ADC by writing to the Prescaler (PRESC) bit field in the Control C (ADCn.CTRLC) register.
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6.
7.
8.
Configure an input by writing to the MUXPOS bit field in the MUXPOS (ADCn.MUXPOS) register.
Optional: Enable Start Event input by writing a ‘1’ to the Start Event Input (STARTEI) bit in the Event Control
(ADCn.EVCTRL) register. Configure the Event System accordingly.
Enable the ADC by writing a ‘1’ to the ENABLE bit in ADCn.CTRLA.
Following these steps will initialize the ADC for basic measurements, which can be triggered by an event (if
configured) or by writing a ‘1’ to the Start Conversion (STCONV) bit in the Command (ADCn.COMMAND) register.
30.3.1.1 I/O Lines and Connections
The I/O pins AINx and VREF are configured by the port - I/O Pin Controller.
The digital input buffer should be disabled on the pin used as input for the ADC to disconnect the digital domain from
the analog domain to obtain the best possible ADC results. This is configured by the PORT peripheral.
30.3.2
Operation
30.3.2.1 Starting a Conversion
Once the input channel is selected by writing to the MUXPOS (ADCn.MUXPOS) register, a conversion is triggered by
writing a ‘1’ to the ADC Start Conversion (STCONV) bit in the Command (ADCn.COMMAND) register. This bit is ‘1’
as long as the conversion is in progress. In Single Conversion mode, STCONV is cleared by hardware when the
conversion is completed.
If a different input channel is selected while a conversion is in progress, the ADC will finish the current conversion
before changing the channel.
Depending on the accumulator setting, the conversion result is from a single sensing operation or a sequence of
accumulated samples. Once the triggered operation is finished, the Result Ready (RESRDY) flag in the Interrupt Flag
(ADCn.INTFLAG) register is set. The corresponding interrupt vector is executed if the Result Ready Interrupt Enable
(RESRDY) bit in the Interrupt Control (ADCn.INTCTRL) register is ‘1’ and the Global Interrupt Enable bit is ‘1’.
A single conversion can be started by writing a ‘1’ to the STCONV bit in ADCn.COMMAND. The STCONV bit can be
used to determine if a conversion is in progress. The STCONV bit will be set during a conversion and cleared once
the conversion is complete.
The RESRDY interrupt flag in ADCn.INTFLAG will be set even if the specific interrupt is disabled, allowing software
to check for finished conversion by polling the flag. A conversion can thus be triggered without causing an interrupt.
Alternatively, a conversion can be triggered by an event. This is enabled by writing a ‘1’ to the Start Event Input
(STARTEI) bit in the Event Control (ADCn.EVCTRL) register. Any incoming event routed to the ADC through the
Event System (EVSYS) will trigger an ADC conversion. This provides a method to start conversions at predictable
intervals or specific conditions.
The event trigger input is edge sensitive. When an event occurs, STCONV in ADCn.COMMAND is set. STCONV will
be cleared when the conversion is complete.
In Free-Running mode, the first conversion is started by writing the STCONV bit to ‘1’ in ADCn.COMMAND. A new
conversion cycle is started immediately after the previous conversion cycle has completed. A conversion complete
will set the RESRDY flag in ADCn.INTFLAGS.
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30.3.2.2 Clock Generation
Figure 30-2. ADC Prescaler
ENABLE
"START"
Reset
8-bit PRESCALER
CTRLC
CLK_PER/256
CLK_PER/128
CLK_PER/64
CLK_PER/32
CLK_PER/16
CLK_PER/8
CLK_PER/4
CLK_PER/2
CLK_PER
PRESC
ADC clock source
(CLK_ADC)
The ADC requires an input clock frequency between 50 kHz and 1.5 MHz for maximum resolution. If a lower
resolution than ten bits is selected, the input clock frequency to the ADC can be higher than 1.5 MHz to get a higher
sample rate.
The ADC module contains a prescaler which generates the ADC clock (CLK_ADC) from any CPU clock (CLK_PER)
above 100 kHz. The prescaling is selected by writing to the Prescaler (PRESC) bits in the Control C (ADCn.CTRLC)
register. The prescaler starts counting from the moment the ADC is switched on by writing a ‘1’ to the ENABLE bit in
ADCn.CTRLA. The prescaler keeps running as long as the ENABLE bit is ‘1’. The prescaler counter is reset to zero
when the ENABLE bit is ‘0’.
When initiating a conversion by writing a ‘1’ to the Start Conversion (STCONV) bit in the Command
(ADCn.COMMAND) register or from an event, the conversion starts at the following rising edge of the CLK_ADC
clock cycle. The prescaler is kept reset as long as there is no ongoing conversion. This assures a fixed delay from
the trigger to the actual start of a conversion in CLK_PER cycles, as follows:
StartDelay =
PRESCfactor
+2
2
Figure 30-3. Start Conversion and Clock Generation
CLK_PER
STCONV
CLK_PER/2
CLK_PER/4
CLK_PER/8
30.3.2.3 Conversion Timing
A normal conversion takes 13 CLK_ADC cycles. The actual sample-and-hold takes place two CLK_ADC cycles after
the start of a conversion. The start of a conversion is initiated by writing a ‘1’ to the STCONV bit in
ADCn.COMMAND. When a conversion is complete, the result is available in the Result (ADCn.RES) register, and the
Result Ready interrupt flag is set (RESRDY in ADCn.INTFLAG). The interrupt flag will be cleared when the result is
read from the Result registers, or by writing a ‘1’ to the RESRDY bit in ADCn.INTFLAG.
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Figure 30-4. ADC Timing Diagram - Single Conversion
Cycle Number
1
2
3
4
5
6
7
9
8
10
11
13
12
CLK_ADC
ENABLE
STCONV
RESRDY
RES
Result
conversion
complete
Both sampling time and sampling length can be adjusted using the Sample Delay bit field in the Control D
(ADCn.CTRLD) register and the Sample Length bit field in the Sample Control (ADCn.SAMPCTRL) register. Both of
these control the ADC sampling time in some CLK_ADC cycles. This allows sampling of high-impedance sources
without relaxing conversion speed. See the register description for further information. Total sampling time is given
by:
sample
SampleTime =
2 + SAMPDLY + SAMPLEN
�CLK_ADC
Figure 30-5. ADC Timing Diagram - Single Conversion With Delays
1
2
3
4
5
6
7
8
9
10
11
12
13
CLK_ADC
ENABLE
STCONV
RES
Result
INITDLY
(0 – 256
CLK_ADC cycles)
SAMPDLY
(0 – 15
CLK_ADC cycles)
SAMPLEN
(0 – 31
CLK_ADC cycles)
In Free-Running mode, a new conversion will be started immediately after the conversion completes, while the
STCONV bit is ‘1’. The sampling rate RS in Free-Running mode is calculated by:
�S =
�CLK_ADC
13 + SAMPDLY + SAMPLEN
Figure 30-6. ADC Timing Diagram - Free-Running Conversion
2
3
4
6
5
7
1
Cycle Number
8
9
10
11
12
13
1
2
CLK_ADC
ENABLE
STCONV
RESRDY
RES
Result
sample
conversion
complete
30.3.2.4 Changing Channel or Reference Selection
The MUXPOS bits in the ADCn.MUXPOS register and the REFSEL bits in the ADCn.CTRLC register are buffered
through a temporary register to which the CPU has random access. This ensures that the channel and reference
selections only take place at a safe point during the conversion. The channel and reference selections are
continuously updated until a conversion is started.
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Once the conversion starts, the channel and reference selections are locked to ensure sufficient sampling time for the
ADC. Continuous updating resumes in the last CLK_ADC clock cycle before the conversion completes (RESRDY in
ADCn.INTFLAGS is set). The conversion starts on the following rising CLK_ADC clock edge after the STCONV bit is
written to ‘1’.
30.3.2.4.1 ADC Input Channels
When changing channel selection, the user must observe the following guidelines to ensure that the correct channel
is selected:
In Single Conversion mode: The channel should be selected before starting the conversion. The channel selection
may be changed one ADC clock cycle after writing ‘1’ to the STCONV bit.
In Free-Running mode: The channel should be selected before starting the first conversion. The channel selection
may be changed one ADC clock cycle after writing ‘1’ to the STCONV bit. Since the next conversion has already
started automatically, the next result will reflect the previous channel selection. The subsequent conversions will
reflect the new channel selection.
The ADC requires a settling time after switching the input channel - refer to the Electrical Characteristics section for
details.
30.3.2.4.2 ADC Voltage Reference
The reference voltage for the ADC (VREF) controls the conversion range of the ADC. Input voltages that exceed the
selected VREF will be converted to the maximum result value of the ADC. For an ideal 10-bit ADC, this value is 0x3FF.
VREF can be selected by writing the Reference Selection (REFSEL) bits in the Control C (ADCn.CTRLC) register as
either VDD, external reference VREFA, or an internal reference from the VREF peripheral. VDD is connected to the ADC
through a passive switch.
When using the external reference voltage VREFA, configure ADCnREFSEL[0:2] in the corresponding VREF.CTRLn
register to the value that is closest, but above the applied reference voltage. For external references higher than
4.3V, use ADCnREFSEL[0:2] = 0x3.
The internal reference is generated from an internal band gap reference through an internal amplifier, controlled by
the Voltage Reference (VREF) peripheral.
30.3.2.4.3 Analog Input Circuitry
The analog input circuitry is illustrated in Figure 30-7. An analog source applied to ADCn is subjected to the pin
capacitance and input leakage of that pin (represented by IH and IL), regardless of whether that channel is selected
as input for the ADC or not. When the channel is selected, the source must drive the S/H capacitor through the series
resistance (combined resistance in the input path).
The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or less. If such a source is
used, the sampling time will be negligible. If a source with higher impedance is used, the sampling time will depend
on how long the source needs to charge the S/H capacitor, which can vary substantially.
Figure 30-7. Analog Input Schematic
IIH
ADCn
Rin
Cin
IIL
VDD/2
30.3.2.5 ADC Conversion Result
After the conversion is complete (RESRDY is ‘1’), the conversion result RES is available in the ADC Result
(ADCn.RES) register. The result of a 10-bit conversion is given as follows:
RES =
1023 × �IN
�REF
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ADC - Analog-to-Digital Converter
where VIN is the voltage on the selected input pin and VREF the selected voltage reference (see description for
REFSEL in ADCn.CTRLC and ADCn.MUXPOS).
30.3.2.6 Temperature Measurement
The temperature measurement is based on an on-chip temperature sensor. For temperature measurement, follow
these steps:
1. Configure the internal voltage reference to 1.1V by configuring the VREF peripheral.
2. Select the internal voltage reference by writing the REFSEL bits in ADCn.CTRLC to 0x0.
3. Select the ADC temperature sensor channel by configuring the MUXPOS (ADCn.MUXPOS) register. This
enables the temperature sensor.
4. In ADCn.CTRLD select INITDLY ≥ 32 µs × �CLK_ADC.
5.
6.
7.
8.
In ADCn.SAMPCTRL select SAMPLEN ≥ 32 µs × �CLK_ADC.
In ADCn.CTRLC select SAMPCAP = 1.
Acquire the temperature sensor output voltage by starting a conversion.
Process the measurement result, as described below.
The measured voltage has a linear relationship to the temperature. Due to process variations, the temperature
sensor output voltage varies between individual devices at the same temperature. The individual compensation
factors are determined during the production test and saved in the Signature Row:
• SIGROW.TEMPSENSE0 is a gain/slope correction
• SIGROW.TEMPSENSE1 is an offset correction
To achieve accurate results, the result of the temperature sensor measurement must be processed in the application
software using factory calibration values. The temperature (in Kelvin) is calculated by this rule:
Temp = (((RESH > 8
RESH and RESL are the high and low bytes of the Result register (ADCn.RES), and TEMPSENSEn are the
respective values from the Signature row.
It is recommended to follow these steps in user code:
int8_t sigrow_offset = SIGROW.TEMPSENSE1; // Read signed value from signature row
uint8_t sigrow_gain = SIGROW.TEMPSENSE0;
// Read unsigned value from signature row
uint16_t adc_reading = 0;
// ADC conversion result with 1.1 V internal reference
uint32_t temp = adc_reading - sigrow_offset;
temp *= sigrow_gain; // Result might overflow 16 bit variable (10bit+8bit)
temp += 0x80;
// Add 1/2 to get correct rounding on division below
temp >>= 8;
// Divide result to get Kelvin
uint16_t temperature_in_K = temp;
30.3.2.7 Window Comparator Mode
The ADC can raise the WCMP flag in the Interrupt and Flag (ADCn.INTFLAG) register and request an interrupt
(WCMP) when the result of a conversion is above and/or below certain thresholds. The available modes are:
• The result is under a threshold
• The result is over a threshold
• The result is inside a window (above a lower threshold, but below the upper one)
• The result is outside a window (either under the lower or above the upper threshold)
The thresholds are defined by writing to the Window Comparator Threshold registers (ADCn.WINLT and
ADCn.WINHT). Writing to the Window Comparator mode (WINCM) bit field in the Control E (ADCn.CTRLE) register
selects the conditions when the flag is raised and/or the interrupt is requested.
Assuming the ADC is already configured to run, follow these steps to use the Window Comparator mode:
1. Choose which Window Comparator to use (see the WINCM description in ADCn.CTRLE), and set the required
threshold(s) by writing to ADCn.WINLT and/or ADCn.WINHT.
2. Optional: enable the interrupt request by writing a ‘1’ to the Window Comparator Interrupt Enable (WCMP) bit
in the Interrupt Control (ADCn.INTCTRL) register.
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ADC - Analog-to-Digital Converter
3.
Enable the Window Comparator and select a mode by writing a non-zero value to the WINCM bit field in
ADCn.CTRLE.
When accumulating multiple samples, the comparison between the result and the threshold will happen after the last
sample was acquired. Consequently, the flag is raised only once, after taking the last sample of the accumulation.
30.3.3
Events
An ADC conversion can be triggered automatically by an event input if the Start Event Input (STARTEI) bit in the
Event Control (ADCn.EVCTRL) register is written to ‘1’.
When a new result can be read from the Result (ADCn.RES) register, the ADC will generate a result ready event.
The event is a pulse with a length of one clock period and handled by the Event System (EVSYS). The ADC result
ready event is always generated when the ADC is enabled.
See also the description of the Asynchronous User Channel n Input Selection in the Event System
(EVSYS.ASYNCUSERn).
30.3.4
Interrupts
Table 30-1. Available Interrupt Vectors and Sources
Name
Vector Description
Conditions
RESRDY Result Ready interrupt
The conversion result is available in the Result register (ADCn.RES)
WCMP
As defined by WINCM in ADCn.CTRLE
Window Comparator interrupt
When an interrupt condition occurs, the corresponding interrupt flag is set in the peripheral’s Interrupt Flags
(peripheral.INTFLAGS) register.
An interrupt source is enabled or disabled by writing to the corresponding enable bit in the peripheral’s Interrupt
Control (peripheral.INTCTRL) register.
An interrupt request is generated when the corresponding interrupt source is enabled, and the interrupt flag is set.
The interrupt request remains active until the interrupt flag is cleared. See the peripheral’s INTFLAGS register for
details on how to clear interrupt flags.
30.3.5
Sleep Mode Operation
The ADC is by default disabled in Standby sleep mode.
The ADC can stay fully operational in Standby sleep mode if the Run in Standby (RUNSTDBY) bit in the Control A
(ADCn.CTRLA) register is written to ‘1’.
When the device is entering Standby sleep mode when RUNSTDBY is ‘1’, the ADC will stay active, hence any
ongoing conversions will be completed, and interrupts will be executed as configured.
In Standby sleep mode, an ADC conversion must be triggered via the Event System (EVSYS), or the ADC must be in
Free-Running mode with the first conversion triggered by software before entering a sleep mode. The peripheral
clock is requested if needed and is turned off after the conversion is completed.
When an input event trigger occurs, the positive edge will be detected, the Start Conversion (STCONV) bit in the
Command (ADCn.COMMAND) register is set, and the conversion will start. When the conversion is completed, the
Result Ready (RESRDY) flag in the Interrupt Flags (ADCn.INTFLAGS) register is set, and the STCONV bit in
ADCn.COMMAND is cleared.
The reference source and supply infrastructure need time to stabilize when activated in Standby sleep mode.
Configure a delay for the start of the first conversion by writing a non-zero value to the Initial Delay (INITDLY) bits in
the Control D (ADCn.CTRLD) register.
In Power-Down sleep mode, no conversions are possible. Any ongoing conversions are halted and will be resumed
when going out of a sleep mode. At the end of conversion, the Result Ready (RESRDY) flag will be set, but the
content of the result (ADCn.RES) registers is invalid since the ADC was halted in the middle of a conversion.
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30.4
Register Summary - ADCn
Offset
Name
Bit Pos.
7
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
...
0x0F
CTRLA
CTRLB
CTRLC
CTRLD
CTRLE
SAMPCTRL
MUXPOS
Reserved
COMMAND
EVCTRL
INTCTRL
INTFLAGS
DBGCTRL
TEMP
7:0
7:0
7:0
7:0
7:0
7:0
7:0
RUNSTBY
0x10
RES
0x12
WINLT
0x14
WINHT
0x16
CALIB
30.5
7:0
7:0
7:0
7:0
7:0
7:0
6
5
4
3
2
1
RESSEL
SAMPCAP
INITDLY[2:0]
REFSEL[1:0]
ASDV
FREERUN
SAMPNUM[2:0]
PRESC[2:0]
SAMPDLY[3:0]
WINCM[2:0]
SAMPLEN[4:0]
MUXPOS[4:0]
WCMP
WCMP
0
ENABLE
STCONV
STARTEI
RESRDY
RESRDY
DBGRUN
TEMP[7:0]
Reserved
7:0
15:8
7:0
15:8
7:0
15:8
7:0
RES[7:0]
RES[15:8]
WINLT[7:0]
WINLT[15:8]
WINHT[7:0]
WINHT[15:8]
DUTYCYC
Register Description
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30.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RUNSTBY
R/W
0
CTRLA
0x00
0x00
-
6
5
4
3
2
RESSEL
R/W
0
1
FREERUN
R/W
0
0
ENABLE
R/W
0
Bit 7 – RUNSTBY Run in Standby
This bit determines whether the ADC needs to run when the chip is in Standby sleep mode.
Bit 2 – RESSEL Resolution Selection
This bit selects the ADC resolution.
Value
Description
0
Full 10-bit resolution. The 10-bit ADC results are accumulated or stored in the ADC Result (ADC.RES)
register.
1
8-bit resolution. The conversion results are truncated to eight bits (MSbs) before they are accumulated
or stored in the ADC Result (ADC.RES) register. The two Least Significant bits (LSbs) are discarded.
Bit 1 – FREERUN Free-Running
Writing a ‘1’ to this bit will enable the Free-Running mode for the data acquisition. The first conversion is started by
writing the STCONV bit in ADC.COMMAND high. In the Free-Running mode, a new conversion cycle is started
immediately after or as soon as the previous conversion cycle has completed. This is signaled by the RESRDY flag in
ADCn.INTFLAGS.
Bit 0 – ENABLE ADC Enable
Value
Description
0
ADC is disabled
1
ADC is enabled
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30.5.2
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x01
0x00
-
6
5
4
3
Access
Reset
2
R/W
0
1
SAMPNUM[2:0]
R/W
0
0
R/W
0
Bits 2:0 – SAMPNUM[2:0] Sample Accumulation Number Select
These bits select how many consecutive ADC sampling results are accumulated automatically. When this bit is
written to a value greater than 0x0, the according number of consecutive ADC sampling results are accumulated into
the ADC Result (ADC.RES) register in one complete conversion.
Value
Name
Description
0x0
NONE
No accumulation
0x1
ACC2
2 results accumulated
0x2
ACC4
4 results accumulated
0x3
ACC8
8 results accumulated
0x4
ACC16
16 results accumulated
0x5
ACC32
32 results accumulated
0x6
ACC64
64 results accumulated
0x7
Reserved
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30.5.3
Control C
Name:
Offset:
Reset:
Property:
Bit
7
Access
Reset
R
0
CTRLC
0x02
0x00
-
6
SAMPCAP
R/W
0
5
4
REFSEL[1:0]
R/W
R/W
0
0
3
2
R
0
R/W
0
1
PRESC[2:0]
R/W
0
0
R/W
0
Bit 6 – SAMPCAP Sample Capacitance Selection
This bit selects the sample capacitance, and hence, the input impedance. The best value is dependent on the
reference voltage and the application's electrical properties.
Value
Description
0
Recommended for reference voltage values below 1V
1
Reduced size of sampling capacitance. Recommended for higher reference voltages.
Bits 5:4 – REFSEL[1:0] Reference Selection
These bits select the voltage reference for the ADC.
Value
Name
Description
0x0
INTERNAL
Internal reference
0x1
VDD
VDD
0x2
VREFA
External reference VREFA
Other
Reserved
Bits 2:0 – PRESC[2:0] Prescaler
These bits define the division factor from the peripheral clock (CLK_PER) to the ADC clock (CLK_ADC).
Value
Name
Description
0x0
DIV2
CLK_PER divided by 2
0x1
DIV4
CLK_PER divided by 4
0x2
DIV8
CLK_PER divided by 8
0x3
DIV16
CLK_PER divided by 16
0x4
DIV32
CLK_PER divided by 32
0x5
DIV64
CLK_PER divided by 64
0x6
DIV128
CLK_PER divided by 128
0x7
DIV256
CLK_PER divided by 256
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30.5.4
Control D
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
R/W
0
CTRLD
0x03
0x00
-
6
INITDLY[2:0]
R/W
0
5
R/W
0
4
ASDV
R/W
0
3
R/W
0
2
1
SAMPDLY[3:0]
R/W
R/W
0
0
0
R/W
0
Bits 7:5 – INITDLY[2:0] Initialization Delay
These bits define the initialization/start-up delay before the first sample when enabling the ADC or changing to an
internal reference voltage. Setting this delay will ensure that the reference, MUXes, etc. are ready before starting the
first conversion. The initialization delay will also take place when waking up from deep sleep to do a measurement.
The delay is expressed as a number of CLK_ADC cycles.
Value
Name
Description
0x0
DLY0
Delay 0 CLK_ADC cycles
0x1
DLY16
Delay 16 CLK_ADC cycles
0x2
DLY32
Delay 32 CLK_ADC cycles
0x3
DLY64
Delay 64 CLK_ADC cycles
0x4
DLY128
Delay 128 CLK_ADC cycles
0x5
DLY256
Delay 256 CLK_ADC cycles
Other
Reserved
Bit 4 – ASDV Automatic Sampling Delay Variation
Writing this bit to ‘1’ enables automatic sampling delay variation between ADC conversions. The purpose of varying
sampling instant is to randomize the sampling instant and thus avoid standing frequency components in the
frequency spectrum. The value of the SAMPDLY bits is automatically incremented by one after each sample.
When the Automatic Sampling Delay Variation is enabled, and the SAMPDLY value reaches 0xF, it wraps around to
0x0.
Value
Name
Description
0
ASVOFF
The Automatic Sampling Delay Variation is disabled
1
ASVON
The Automatic Sampling Delay Variation is enabled
Bits 3:0 – SAMPDLY[3:0] Sampling Delay Selection
These bits define the delay between consecutive ADC samples. The programmable sampling delay allows modifying
the sampling frequency during hardware accumulation to suppress periodic noise sources that may otherwise disturb
the sampling. The SAMPDLY field can also be modified automatically from one sampling cycle to another, by setting
the ASDV bit. The delay is expressed as CLK_ADC cycles and is given directly by the bit field setting. The sampling
cap is kept open during the delay.
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30.5.5
Control E
Name:
Offset:
Reset:
Property:
Bit
7
CTRLE
0x4
0x00
-
6
5
4
3
Access
Reset
2
R/W
0
1
WINCM[2:0]
R/W
0
0
R/W
0
Bits 2:0 – WINCM[2:0] Window Comparator Mode
This bit field enables and defines when the interrupt flag is set in Window Comparator mode. RESULT is the 16-bit
accumulator result. WINLT and WINHT are 16-bit lower threshold value and 16-bit higher threshold value,
respectively.
Value
Name
Description
0x0
NONE
No Window Comparison (default)
0x1
BELOW
RESULT < WINLT
0x2
ABOVE
RESULT > WINHT
0x3
INSIDE
WINLT < RESULT < WINHT
0x4
OUTSIDE
RESULT < WINLT or RESULT > WINHT
Other
Reserved
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30.5.6
Sample Control
Name:
Offset:
Reset:
Property:
Bit
7
SAMPCTRL
0x5
0x00
-
6
Access
Reset
5
4
3
R/W
0
R/W
0
2
SAMPLEN[4:0]
R/W
0
1
0
R/W
0
R/W
0
Bits 4:0 – SAMPLEN[4:0] Sample Length
These bits extend the ADC sampling length in several CLK_ADC cycles. By default, the sampling time is two
CLK_ADC cycles. Increasing the sampling length allows sampling sources with higher impedance. The total
conversion time increases with the selected sampling length.
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30.5.7
MUXPOS
Name:
Offset:
Reset:
Property:
Bit
MUXPOS
0x06
0x00
-
7
6
Access
Reset
5
4
3
R/W
0
R/W
0
2
MUXPOS[4:0]
R/W
0
1
0
R/W
0
R/W
0
Bits 4:0 – MUXPOS[4:0] MUXPOS
This bit field selects which single-ended analog input is connected to the ADC. If these bits are changed during a
conversion, the change will not take effect until this conversion is complete.
Value
Name
Description
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x1C
0x1D
0x1E
0x1F
Other
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AIN8
AIN9
AIN10
AIN11
DAC0
INTREF
TEMSENSE
GND
-
ADC input pin 0
ADC input pin 1
ADC input pin 2
ADC input pin 3
ADC input pin 4
ADC input pin 5
ADC input pin 6
ADC input pin 7
ADC input pin 8
ADC input pin 9
ADC input pin 10
ADC input pin 11
DAC0
Internal reference (from VREF peripheral)
Temperature sensor
0V (GND)
Reserved
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30.5.8
Command
Name:
Offset:
Reset:
Property:
Bit
7
COMMAND
0x08
0x00
-
6
5
4
3
Access
Reset
2
1
0
STCONV
R/W
0
Bit 0 – STCONV Start Conversion
Writing a ‘1’ to this bit will start a single measurement. If in Free-Running mode, this will start the first conversion.
STCONV will read as ‘1’ as long as a conversion is in progress. When the conversion is complete, this bit is
automatically cleared.
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30.5.9
Event Control
Name:
Offset:
Reset:
Property:
Bit
7
EVCTRL
0x09
0x00
-
6
5
4
3
Access
Reset
2
1
0
STARTEI
R/W
0
Bit 0 – STARTEI Start Event Input
This bit enables using the event input as a trigger for starting a conversion.
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30.5.10 Interrupt Control
Name:
Offset:
Reset:
Property:
Bit
7
INTCTRL
0x0A
0x00
-
6
5
4
3
Access
Reset
2
1
WCMP
R/W
0
0
RESRDY
R/W
0
Bit 1 – WCMP Window Comparator Interrupt Enable
Writing a ‘1’ to this bit enables the window comparator interrupt.
Bit 0 – RESRDY Result Ready Interrupt Enable
Writing a ‘1’ to this bit enables the result ready interrupt.
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30.5.11 Interrupt Flags
Name:
Offset:
Reset:
Property:
Bit
7
INTFLAGS
0x0B
0x00
-
6
5
4
3
Access
Reset
2
1
WCMP
R/W
0
0
RESRDY
R/W
0
Bit 1 – WCMP Window Comparator Interrupt Flag
This window comparator interrupt flag is set when the measurement is complete and if the result matches the
selected Window Comparator mode defined by WINCM (ADCn.CTRLE). The comparison is done at the end of the
conversion. The flag is cleared by either writing a ‘1’ to the bit position or by reading the Result (ADCn.RES) register.
Writing a ‘0’ to this bit has no effect.
Bit 0 – RESRDY Result Ready Interrupt Flag
The Result Ready interrupt flag is set when a measurement is complete, and a new result is ready. The flag is
cleared by either writing a ‘1’ to the bit location or by reading the Result (ADCn.RES) register. Writing a ‘0’ to this bit
has no effect.
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30.5.12 Debug Run
Name:
Offset:
Reset:
Property:
Bit
7
DBGCTRL
0x0C
0x00
-
6
5
4
3
2
Access
Reset
1
0
DBGRUN
R/W
0
Bit 0 – DBGRUN Debug Run
Value
Description
0
The peripheral is halted in Break Debug mode and ignores events
1
The peripheral will continue to run in Break Debug mode when the CPU is halted
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30.5.13 Temporary
Name:
Offset:
Reset:
Property:
TEMP
0x0D
0x00
-
The Temporary register is used by the CPU for 16-bit single-cycle access to the 16-bit registers of this peripheral. The
register is common for all the 16-bit registers of this peripheral and can be read and written by software. For more
details on reading and writing 16-bit registers, refer to Accessing 16-Bit Registers in the AVR CPU section.
Bit
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
TEMP[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – TEMP[7:0] Temporary
Temporary register for read/write operations in 16-bit registers.
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30.5.14 Result
Name:
Offset:
Reset:
Property:
RES
0x10
0x00
-
The ADCn.RESL and ADCn.RESH register pair represents the 16-bit value, ADCn.RES. The low byte [7:0] (suffix L)
is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
If the analog input is higher than the reference level of the ADC, the 10-bit ADC result will be equal the maximum
value of 0x3FF. Likewise, if the input is below 0V, the ADC result will be 0x000. As the ADC cannot produce a result
above 0x3FF values, the accumulated value will never exceed 0xFFC0 even after the maximum allowed 64
accumulations.
Bit
15
14
13
12
11
10
9
8
R
0
R
0
R
0
R
0
3
2
1
0
R
0
R
0
R
0
R
0
RES[15:8]
Access
Reset
R
0
R
0
R
0
R
0
Bit
7
6
5
4
RES[7:0]
Access
Reset
R
0
R
0
R
0
R
0
Bits 15:8 – RES[15:8] Result high byte
These bits constitute the MSB of the ADCn.RES register, where the MSb is RES[15]. The ADC itself has a 10-bit
output, ADC[9:0], where the MSb is ADC[9]. The data format in ADC and Digital Accumulation is 1’s complement,
where 0x0000 represents the zero, and 0xFFFF represents the largest number (full scale).
Bits 7:0 – RES[7:0] Result low byte
These bits constitute the LSB of ADC/Accumulator Result, (ADCn.RES) register. The data format in ADC and Digital
Accumulation is 1’s complement, where 0x0000 represents the zero, and 0xFFFF represents the largest number (full
scale).
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30.5.15 Window Comparator Low Threshold
Name:
Offset:
Reset:
Property:
WINLT
0x12
0x00
-
This register is the 16-bit low threshold for the digital comparator monitoring the ADCn.RES register. The ADC itself
has a 10-bit output, RES[9:0], where the MSb is RES[9]. The data format in ADC and Digital Accumulation is 1’s
complement, where 0x0000 represents the zero, and 0xFFFF represents the largest number (full scale).
The ADCn.WINLTH and ADCn.WINLTL register pair represents the 16-bit value, ADCn.WINLT. The low byte [7:0]
(suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
When accumulating samples, the window comparator thresholds are applied to the accumulated value and not on
each sample.
Bit
Access
Reset
Bit
15
14
13
R/W
0
R/W
0
R/W
0
7
6
5
12
11
WINLT[15:8]
R/W
R/W
0
0
4
10
9
8
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
WINLT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – WINLT[15:8] Window Comparator Low Threshold High Byte
These bits hold the MSB of the 16-bit register.
Bits 7:0 – WINLT[7:0] Window Comparator Low Threshold Low Byte
These bits hold the LSB of the 16-bit register.
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30.5.16 Window Comparator High Threshold
Name:
Offset:
Reset:
Property:
WINHT
0x14
0x00
-
This register is the 16-bit high threshold for the digital comparator monitoring the ADCn.RES register. The ADC itself
has a 10-bit output, RES[9:0], where the MSb is RES[9]. The data format in ADC and Digital Accumulation is 1’s
complement, where 0x0000 represents the zero, and 0xFFFF represents the largest number (full scale).
The ADCn.WINHTH and ADCn.WINHTL register pair represents the 16-bit value, ADCn.WINHT. The low byte [7:0]
(suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01.
Bit
Access
Reset
Bit
15
14
13
R/W
0
R/W
0
R/W
0
7
6
5
12
11
WINHT[15:8]
R/W
R/W
0
0
4
10
9
8
R/W
0
R/W
0
R/W
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
WINHT[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 15:8 – WINHT[15:8] Window Comparator High Threshold High Byte
These bits hold the MSB of the 16-bit register.
Bits 7:0 – WINHT[7:0] Window Comparator High Threshold Low Byte
These bits hold the LSB of the 16-bit register.
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30.5.17 Calibration
Name:
Offset:
Reset:
Property:
Bit
7
CALIB
0x16
0x01
-
6
5
4
3
2
Access
Reset
1
0
DUTYCYC
R/W
1
Bit 0 – DUTYCYC Duty Cycle
This bit determines the duty cycle of the ADC clock.
ADCclk > 1.5 MHz requires a minimum operating voltage of 2.7V.
Value
Description
0
50% Duty Cycle must be used if ADCclk > 1.5 MHz
1
25% Duty Cycle (high 25% and low 75%) must be used for ADCclk ≤ 1.5 MHz
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DAC - Digital-to-Analog Converter
31.
DAC - Digital-to-Analog Converter
31.1
Features
•
•
•
•
31.2
8-bit Resolution
Up to 350 ksps Conversion Rate
High Drive Capabilities (DAC0)
Functioning as Input to Analog Comparator (AC) or Analog-to-Digital Converter (ADC)
Overview
The Digital-to-Analog Converter (DAC) converts a digital value written to the Data (DAC.DATA) register to an analog
voltage. The conversion range is between GND and the selected reference voltage.
The DAC features an 8-bit resistor-string type DAC, capable of converting 350,000 samples per second (350 ksps).
The DAC uses the internal Voltage Reference (VREF) as the upper limit for conversion and has one continuous time
output with high drive capabilities, which can drive a 5 kΩ and/or 30 pF load. The DAC conversion can be started
from the application by writing to the Data Conversion registers.
31.2.1
Block Diagram
Figure 31-1. DAC Block Diagram
Other
Peripherals
DATA
8
DAC
Output
Driver
OUT
VREF
ENABLE
CTRLA
OUTEN
Note: Only DAC0 has an output driver for an external pin.
31.2.2
31.2.3
Signal Description
Signal
Description
Type
OUT
DAC output
Analog
System Dependencies
To use this peripheral, other parts of the system must be configured correctly, as described below.
Table 31-1. DAC System Dependencies
Dependency
Applicable
Peripheral
Clocks
Yes
CLKCTRL
I/O Lines and Connections
Yes
PORT
Interrupts
No
-
Events
No
-
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DAC - Digital-to-Analog Converter
...........continued
Dependency
Applicable
Peripheral
Debug
Yes
UPDI
31.2.3.1 Clocks
This peripheral depends on the peripheral clock.
31.2.3.2 I/O Lines and Connections
Using the I/O lines of the peripheral requires configuration of the I/O pins.
Table 31-2. I/O Lines
Instance
Signal
I/O Line
Peripheral Function
DAC0
OUT
PA6
A
The DAC0 has one analog output pin (OUT) that must be configured before it can be used.
A DAC is also internally connected to the AC and the ADC. To use this internal OUT as input, both output and input
must be configured in their respective registers.
31.2.3.3 Events
Not applicable.
31.2.3.4 Interrupts
Not applicable.
31.2.3.5 Debug Operation
This peripheral is unaffected by entering Debug mode.
If the peripheral is configured to require periodic service by the CPU through interrupts or similar, improper operation
or data loss may result during halted debugging.
31.3
Functional Description
31.3.1
Initialization
To operate the DAC, the following steps are required:
1.
2.
3.
4.
5.
31.3.2
Select the DAC reference voltage in the Voltage Reference (VREF) peripheral by writing the DAC and AC
Reference Selection (DACnREFSEL) bits in the Control x (VREF.CTRLx) register.
The conversion range is between GND and the selected reference voltage.
Configure the further usage of the DAC output:
3.1.
Configure an internal peripheral (e.g., AC, ADC) to use the DAC output. Refer to the according
peripheral’s documentation.
3.2.
Enable the output to a pin by writing a ‘1’ to the Output Enable (OUTEN) bit in the Control A
(DAC.CTRLA) register. This requires a configuration of the Port peripheral.
For DAC0, either one or both options are valid. Other instances of the DAC only support internal signaling.
Write an initial digital value to the Data (DAC.DATA) register.
Enable the DAC by writing a ‘1’ to the ENABLE bit in the DAC.CTRLA register.
Operation
31.3.2.1 Enabling, Disabling and Resetting
The DAC is enabled by writing a ‘1’ to the ENABLE bit in the Control A (DACn.CTRLA) register and disabled by
writing a ‘0’ to this bit.
The OUT output to a pin is enabled by writing the Output Enable (OUTEN) bit in the DACn.CTRLA register.
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DAC - Digital-to-Analog Converter
31.3.2.2 Starting a Conversion
When the DAC is enabled (ENABLE = ‘1’ in DACn.CTRLA), a conversion starts as soon as the Data (DACn.DATA)
register is written.
When the DAC is disabled (ENABLE = ‘0’ in DACn.CTRLA), writing to the DACn.DATA register does not trigger a
conversion. Instead, the conversion starts on writing a ‘1’ to the ENABLE bit in the DACn.CTRLA register.
31.3.2.3 DAC as Source For Internal Peripherals
The analog output of the DAC is internally connected to both the AC and the ADC and is available to these
peripherals when the DAC is enabled (ENABLE = ‘1’ in DAC.CTRLA). When the DAC analog output is only being
used internally, it is not necessary to enable the pin output driver (i.e., OUTEN = ‘0’ in DAC.CTRLA is acceptable).
31.3.3
Sleep Mode Operation
If the Run in Standby (RUNSTDBY) bit in the Control A (DAC.CTRLA) register is written to ‘1’ and CLK_PER is
available, the DAC will continue to operate in Standby sleep mode. If the RUNSTDBY bit is ‘0’, the DAC will stop the
conversion in Standby sleep mode.
If the conversion is stopped in Standby sleep mode, the DAC and the output buffer are disabled to reduce power
consumption. When the device is exiting Standby sleep mode, the DAC and the output buffer (if configured by
OUTEN = ‘1’ in DAC.CTRLA) are enabled again. Therefore, certain start-up time is required before a new conversion
is initiated.
In Power-Down sleep mode, the DAC and output buffer are disabled to reduce the power consumption.
31.3.4
Configuration Change Protection
Not applicable.
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DAC - Digital-to-Analog Converter
31.4
Register Summary
Offset
Name
Bit Pos.
7
6
0x00
0x01
CTRLA
DATA
7:0
7:0
RUNSTDBY
OUTEN
31.5
5
4
3
2
1
0
ENABLE
DATA[7:0]
Register Description
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DAC - Digital-to-Analog Converter
31.5.1
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
RUNSTDBY
R/W
0
CTRLA
0x00
0x00
-
6
OUTEN
R/W
0
5
4
3
2
1
0
ENABLE
R/W
0
Bit 7 – RUNSTDBY Run in Standby Mode
If this bit is written to ‘1’, the DAC or output buffer will not automatically be disabled when the device is entering
Standby sleep mode.
Bit 6 – OUTEN Output Buffer Enable
Writing a ‘1’ to this bit enables the output buffer and sends the OUT signal to a pin.
Bit 0 – ENABLE DAC Enable
Writing a ‘1’ to this bit enables the DAC.
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31.5.2
DATA
Name:
Offset:
Reset:
Property:
Bit
7
DATA
0x01
0x00
-
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA[7:0]
Access
Reset
R/W
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – DATA[7:0] Data
This bit field contains the digital data, which will be converted to an analog voltage.
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UPDI - Unified Program and Debug Interface
32.
UPDI - Unified Program and Debug Interface
32.1
Features
•
•
•
32.2
UPDI One-Wire Interface for External Programming and On-Chip-Debugging (OCD)
– Enable programming by high-voltage or fuse
– Uses the RESET pin of the device for programming
– No GPIO pins occupied during the operation
– Asynchronous half-duplex UART protocol towards the programmer
Programming:
– Built-in error detection and error signature generation
– Override of response generation for faster programming
Debugging:
– Memory-mapped access to device address space (NVM, RAM, I/O)
– No limitation on the device clock frequency
– Unlimited number of user program breakpoints
– Two hardware breakpoints
– Support for advanced OCD features
• Run-time readout of the CPU Program Counter (PC), Stack Pointer (SP) and Status Register (SREG)
for code profiling
• Detection and signalization of the Break/Stop condition in the CPU
• Program flow control for Run, Stop and Reset debug instructions
– Nonintrusive run-time chip monitoring without accessing the system registers
– Interface for reading the result of the CRC check of the Flash on a locked device
Overview
The Unified Program and Debug Interface (UPDI) is a proprietary interface for external programming and OCD of a
device.
The UPDI supports programming of Nonvolatile Memory (NVM) space, Flash, EEPROM, fuses, lock bits, and the
user row. Some memory-mapped registers are accessible only with the correct access privilege enabled (key, lock
bits) and only in the OCD Stopped mode or certain Programming modes. These modes are unlocked by sending the
correct key to the UPDI. See the NVMCTRL - Nonvolatile Memory Controller section for programming via the NVM
controller and executing NVM controller commands.
The UPDI is partitioned into three separate protocol layers: the UPDI Physical (PHY) Layer, the UPDI Data Link (DL)
Layer and the UPDI Access (ACC) Layer. The default PHY layer handles bidirectional UART communication over the
UPDI pin line towards a connected programmer/debugger and provides data recovery and clock recovery on an
incoming data frame in the One-Wire Communication mode. Received instructions and corresponding data are
handled by the DL layer, which sets up the communication with the ACC layer based on the decoded instruction.
Access to the system bus and memory-mapped registers is granted through the ACC layer.
Programming and debugging are done through the PHY layer, which is a one-wire UART based on a half-duplex
interface using the RESET pin for data reception and transmission. The clocking of the PHY layer is done by a
dedicated internal oscillator.
The ACC layer is the interface between the UPDI and the connected bus matrix. This layer grants access via the
UPDI interface to the bus matrix with memory-mapped access to system blocks such as memories, NVM, and
peripherals.
The Asynchronous System Interface (ASI) provides direct interface access to select features in the OCD, NVM, and
System Management systems. This gives the debugger direct access to system information without requesting bus
access.
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UPDI - Unified Program and Debug Interface
32.2.1
Block Diagram
Figure 32-1. UPDI Block Diagram
ASI
Memories
UPDI Pin
(RX/TX Data)
UPDI
Physical
layer
UPDI
Access
layer
Bus Matrix
UPDI Controller
NVM
Peripherals
ASI Access
32.2.2
OCD
NVM
Controller
System
Management
ASI Internal Interfaces
Clocks
The PHY layer and the ACC layer can operate on different clock domains. The PHY layer clock is derived from the
dedicated internal oscillator, and the ACC layer clock is the same as the peripheral clock. There is a synchronization
boundary between the PHY and the ACC layer, which ensures correct operation between the clock domains. The
UPDI clock output frequency is selected through the ASI, and the default UPDI clock start-up frequency is 4 MHz
after enabling or resetting the UPDI. The UPDI clock frequency can be changed by writing to the UPDI Clock Divider
Select (UPDICLKSEL) bit field in the ASI Control A (UPDI.ASI_CTRLA) register.
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UPDI - Unified Program and Debug Interface
Figure 32-2. UPDI Clock Domains
ASI
SYNCH
UPDI Controller
UPDI
Physical
layer
Clock
Controller
32.2.3
Clock
Controller
CLK_UPDI
CLK_UPDI
source
~
UPDI
Access
layer
CLK_PER
CLK_PER
UPDICLKSEL
~
Physical Layer
The PHY layer is the communication interface between a connected programmer/debugger and the device. The main
features of the PHY layer can be summarized as follows:
• Support for UPDI One-Wire mode, using asynchronuous, half-duplex UART communication on the UPDI pin
• Internal baud detection, clock and data recovery on the UART frame
• Error detection (parity, clock recovery, frame, system errors)
• Transmission response generation (ACK)
• Generation of error signatures during operation
• Guard time control
32.2.4
I/O Lines and Connections
To operate the UPDI, the RESET pin must be set to UPDI mode. This is not done through the port I/O pin
configuration as regular I/O pins but through setting the RESET Pin Configuration (RSTPINCFG) bits in
FUSE.SYSCFG0, as described in UPDI Enable with Fuse Override of RESET Pin, or by following the UPDI highvoltage enable sequence from UPDI Enable with High-Voltage Override of RESET Pin. Pull enable, input enable, and
output enable settings are automatically controlled by the UPDI when active.
32.3
Functional Description
32.3.1
Principle of Operation
The communication through the UPDI is based on standard UART communication, using a fixed frame format, and
automatic baud rate detection for clock and data recovery. In addition to the data frame, several control frames are
important to the communication: DATA, IDLE, BREAK, SYNCH, ACK.
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UPDI - Unified Program and Debug Interface
Figure 32-3. Supported UPDI Frame Formats
DATA
St
0
1
2
3
4
5
6
7
P
S1 S2
P
S1 S2
P
S1 S2
IDLE
BREAK
SYNCH (0x55)
St
Synch Part
End_synch
ACK (0x40)
St
Frame
Description
DATA
A DATA frame consists of one Start (St) bit, which is always low, eight Data bits, one Parity (P) bit for
even parity, and two Stop (S1 and S2) bits, which are always high. If the Parity bit or Stop bits have an
incorrect value, an error will be detected and signalized by the UPDI. The parity bit-check in the UPDI can
be disabled by writing to the Parity Disable (PARD) bit in the Control A (UPDI.CTRLA) register, in which
case the parity generation from the debugger is ignored.
IDLE
This is a special frame that consists of at least 12 high bits. This is the same as keeping the transmission
line in an Idle state.
BREAK
This is a special frame that consists of at least 12 low bits. It is used to reset the UPDI back to its default
state and is typically used for error recovery.
SYNCH The SYNCH frame is used by the Baud Rate Generator to set the baud rate for the coming transmission.
A SYNCH character is always expected by the UPDI in front of every new instruction, and after a
successful BREAK has been transmitted.
ACK
The ACK frame is transmitted from the UPDI whenever an ST or an STS instruction has successfully
crossed the synchronization boundary and gained bus access. When an ACK is received by the
debugger, the next transmission can start.
32.3.1.1 UPDI UART
The communication is initiated from the debugger/programmer side. Every transmission must start with a SYNCH
character, which the UPDI can use to recover the transmission baud rate and store this setting for the incoming data.
The baud rate set by the SYNCH character will be used for both reception and transmission of the subsequent
instruction and data bytes. See the UPDI Instruction Set section for details on when the next SYNCH character is
expected in the instruction stream.
There is no writable Baud Rate register in the UPDI, so the baud rate sampled from the SYNCH character is used for
data recovery when sampling the data byte.
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The transmission baud rate of the PHY layer is related to the selected UPDI clock, which can be adjusted by writing
to the UPDI Clock Divider Select (UPDICLKSEL) bit field in the ASI Control A (UPDI.ASI_CTRLA) register. The
receive and transmit baud rates are always the same within the accuracy of the auto-baud.
Table 32-1. Recommended UART Baud Rate Based on UPDICLKSEL Setting
UPDICLKSEL[1:0]
Max. Recommended Baud Rate
Min. Recommended Baud Rate
0x1 (16 MHz)
0.9 Mbps
0.300 kbps
0x2 (8 MHz)
450 kbps
0.150 kbps
0x3 (4 MHz) - Default
225 kbps
0.075 kbps
The UPDI Baud Rate Generator utilizes fractional baud counting to minimize the transmission error. With the fixed
frame format used by the UPDI, the maximum and recommended receiver transmission error limits can be seen in
Table 32-2.
Table 32-2. Receiver Baud Rate Error
Data + Parity Bits
Rslow
Rfast
Max. Total Error [%]
Recommended Max. RX Error [%]
9
96.39
104.76
+4.76/-3.61
+1.5/-1.5
32.3.1.2 BREAK Character
The BREAK character is used to reset the internal state of the UPDI to the default setting. This is useful if the UPDI
enters an Error state due to a communication error or when the synchronization between the debugger and the UPDI
is lost.
To ensure that a BREAK is successfully received by the UPDI in all cases, the debugger must send two consecutive
BREAK characters. The first BREAK will be detected if the UPDI is in Idle state and will not be detected if it is sent
while the UPDI is receiving or transmitting (at a very low baud rate). However, this will cause a frame error for the
reception (RX) or a contention error for the transmission (TX), and abort the ongoing operation. The UPDI will then
detect the next BREAK successfully.
Upon receiving a BREAK, the UPDI oscillator setting in the ASI Control A (UPDI.ASI_CTRLA) register is reset to the
4 MHz default UPDI clock selection. This changes the baud rate range of the UPDI, according to Table 32-1.
32.3.1.2.1 BREAK in One-Wire Mode
In One-Wire mode, the programmer/debugger and UPDI can be totally out of synch, requiring a worst-case length for
the BREAK character to be sure that the UPDI can detect it. Assuming the slowest UPDI clock speed of 4 MHz (250
ns), the maximum length of the 8-bit SYNCH pattern value that can be contained in 16 bits is
65535 × 250 ns = 16.4 ms/byte = 16.4 ms/8 bits = 2.05 ms/bit.
This gives a worst-case BREAK frame duration of
2.05 ms × 12bits ≈ 24.6 ms
for the slowest prescaler setting. When the prescaler setting is known, the time of the BREAK frame can be relaxed
according to the values from Table 32-3.
Table 32-3. Recommended BREAK Character Duration
UPDICLKSEL[1:0]
Recommended BREAK Character Duration
0x1 (16 MHz)
6.15 ms
0x2 (8 MHz)
12.30 ms
0x3 (4 MHz)
24.60 ms
32.3.1.3 SYNCH Character
The SYNCH character has eight bits and follows the regular UPDI frame format. It has a fixed value of 0x55. The
SYNCH character has two main purposes:
1. It acts as the enabling character for the UPDI after a disable.
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2.
It is used by the Baud Rate Generator to set the baud rate for the subsequent transmission. If an invalid
SYNCH character is sent, the next transmission will not be sampled correctly.
32.3.1.3.1 SYNCH in One-Wire Mode
The SYNCH character is used before each new instruction. When using the REPEAT instruction, the SYNCH
character is expected only before the first instruction after REPEAT.
The SYNCH is a known character which, through its property of toggling for each bit, allows the UPDI to measure
how many UPDI clock cycles are needed to sample the 8-bit SYNCH pattern. The information obtained through the
sampling is used to provide Asynchronous Clock Recovery and Asynchronous Data Recovery on reception, and to
keep the baud rate of the connected programmer when doing transmit operations.
32.3.2
Operation
The UPDI must be enabled before the UART communication can start.
32.3.2.1 UPDI Enabling
The enable sequence for the UPDI is device independent and is described in the following paragraphs.
32.3.2.1.1 One-Wire Enable
The UPDI pin has an internal pull-up resistor, and by driving the UPDI pin low for more than 200 ns, a connected
programmer will initiate the start-up sequence.
The negative edge transition will cause an edge detector (located in the high-voltage domain if it is in a Multi-Voltage
System) to start driving the UPDI pin low, so when the programmer releases the line, it will stay low until the
requested UPDI oscillator is ready. The expected arrival time for the clock will depend on the oscillator
implementation regarding the accuracy, overshoot, and readout of the oscillator calibration. For a Multi-Voltage
System, the line will be driven low until the regulator is at the correct level, and the system is powered up with the
selected oscillator ready and stable. The programmer must poll the UPDI pin after releasing it the first time to detect
when the pin transitions to high again. This transition means that the edge detector has released the pin (pull-up),
and the UPDI can receive a SYNCH character. Upon successful detection of the SYNCH character, the UPDI is
enabled and will prepare for the reception of the first instruction.
The enable transmission sequence is shown in the next figure, where the active driving periods for the programmer
and edge detector are included. The “UPDI pin” waveform shows the pin value at any given time.
The delay given for the edge detector active drive period is a typical start-up time waiting for 256 cycles on a 32 MHz
oscillator + the calibration readout. Refer to the Electrical Characteristics section for details on the expected start-up
times.
Note: The first instruction issued after the initial enable SYNCH does not need an extra SYNCH to be sent because
the enable sequence SYNCH sets up the Baud Rate Generator for the first instruction.
To avoid the UPDI from staying enabled if an accidental trigger of the edge detector happens, the UPDI will
automatically disable itself and lower its clock request. See 32.3.2.2.1 Disable During Start-up for more details.
UPDI Enable with Fuse Override of RESET Pin
When the RESET Pin Configuration (RSTPINCFG) bit in FUSE.SYSCFG0 is 0x1, the RESET pin will be overridden,
and the UPDI will take control of the pin and configure it as an input with pull-up.
When the pull-up is detected, the debugger initiates the enable sequence by driving the line low for a duration of
tDeb0, as depicted in Figure 32-4:
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UPDI - Unified Program and Debug Interface
Figure 32-4. UPDI Enable Sequence with UPDI PAD Enabled By Fuse
1
Fuse read in. Pull-up enabled. Ready to receive init.
2
Drive low from the debugger to request the UPDI clock.
3
UPDI clock ready; Communication channel ready.
RESET
1
2
Hi-Z
St
D0
D1
D2
Handshake / BREAK
UPDI.txd
D4
D5
D6
D7
Sp
SYNC (0x55)
(Auto-baud)
t RES
UPDI.rxd
D3
(Ignore)
3
Hi-Z
Hi-Z
UPDI.txd = 0
t UPDI
debugger.
UPDI.txd
Hi-Z
Hi-Z
Debugger.txd = 0
Debugger.txd = z
t Deb0
t DebZ
When the negative edge is detected, the UPDI clock starts. The UPDI will continue to drive the line low until the clock
is stable and ready for the UPDI to use. The duration of tUPDI will vary, depending on the status of the oscillator when
the UPDI is enabled. After this duration, the data line will be released by the UPDI and pulled high.
When the debugger detects that the line is high, the initial SYNCH character 0x55 must be transmitted to
synchronize the UPDI communication data rate. If the Start bit of the SYNCH character is not sent within maximum
tDebZ, the UPDI will disable itself, and the UPDI enabling sequence must be reinitiated. If the timing is violated, the
UPDI is disabled to avoid unintentional enabling of the UPDI.
After a successful SYNCH character transmission, the first instruction frame can be transmitted.
UPDI Enable with High-Voltage Override of RESET Pin
GPIO or Reset functionality on the RESET pin can be overridden by the UPDI by using high-voltage (HV)
programming. Applying an HV pulse to the RESET pin will switch the pin functionality to UPDI. This is independent of
the RESET Pin Configuration (RSTPINCFG) in FUSE.SYSCFG0. Follow these steps to override the pin functionality:
1. Recommended: Reset the device before starting the HV enable sequence.
2. Apply the HV signal, as described in Figure 32-5.
3. Send the NVMPROG key using the key instruction after the first SYNC character to start programming.
Locked devices will only accept the CHIPERASE key. See also section Chip Erase.
4. After the programming is finished, reset the UPDI by writing the UPDI Disable (UPDIDIS) bit in the Control B
(UPDI.CTRLB) register to ‘1’ using the STCS instruction.
During power-up, the RESET signal must be released before the HV pulse can be applied. The duration of the pulse
is recommended in the range from 100 μs to 1 ms before tri-stating.
When applying the rising edge of the HV pulse, the UPDI will be reset. After tri-stating, the UPDI will remain in Reset
until the RESET pin is driven low by the debugger. This will release the UPDI Reset and initiate the same enable
sequence, as explained in UPDI Enable with Fuse Override of RESET Pin.
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UPDI - Unified Program and Debug Interface
Figure 32-5. UPDI Enable Sequence by High-Voltage (HV) Programming
1 Fused pin function disabled; UPDI pin function enabled.
2
UPDI interface enabled with pull-up.
1
(Ignore)
St
Hi-Z
D0
D1
D2
D3
D4
D5
D6
D7
Sp
UPDIPAD
HV ramp
t HV_ramp
Min. is 10 ns
Max. is 4 ms
Debugger.txd = z
t DebZ
Min. is 1 μs
Max. is 10 μs
Handshake/BREAK
SYNC (0x55)
(Auto-baud)
t RES
Min. is 10 μs
Max. is 200 μs
(Ignore)
UPDI.rxd
Hi-Z
UPDI.txd
Hi-Z
2
UPDI.txd = 0
t UPDI
Min. is 10 μs
Max. is 200 μs
debugger
UPDI.txd
debugger
UPDI HV
Hi-Z
HV
Vdd
Hi-Z
Debugger.txd = 0
Debugger.txd = z
t Deb0
Min. is 200 ns
Max. is 1 μs
t DebZ
Min. is 200 μs
Max. is 14 ms
When enabled by an HV pulse, only a POR will disable the UPDI configuration on the RESET pin and restore the
default setting. If issuing a UPDI Disable command through the UPDIDIS bit in UPDI.CTRLB, the UPDI will be reset,
and the clock request will be canceled, but the RESET pin will remain in UPDI configuration.
Notes:
1. If insufficient external protection is added to the UPDI pin, an ESD pulse can be interpreted by the device as a
high-voltage override and enable the UPDI.
2. The actual threshold voltage for the UPDI HV activation depends on VDD. See the Electrical Characteristics
section for more details.
Output Enable Timer Protection for GPIO Configuration
When the RESET Pin Configuration (RSTPINCFG) bit in FUSE.SYSCFG0 is ‘0x0’, the RESET pin is configured as
GPIO. To avoid a potential conflict between the GPIO actively driving the output and a UPDI high-voltage (HV) enable
sequence initiation, the GPIO output driver is disabled for a minimum of 8.8 ms after a System Reset.
It is always recommended to issue a Power-On Reset (POR) before entering the HV programming sequence.
32.3.2.2 UPDI Disabling
32.3.2.2.1 Disable During Start-up
During the enable sequence, the UPDI can disable itself in case of an invalid enable sequence. There are two
mechanisms implemented to reset any requests the UPDI has given to the Power Management and set the UPDI to
the disabled state. A new enable sequence must then be initiated to enable the UPDI.
Time-Out Disable
When the start-up negative edge detector releases the pin after the UPDI has received its clock, or when the
regulator is stable and the system has power in a Multi-Voltage system, the default pull-up drives the UPDI pin high. If
the programmer does not detect that the pin is high, and does not initiate a transmission of the SYNCH character
within 16.4 ms at 4 MHz UPDI clock after the UPDI has released the pin, the UPDI will disable itself.
Note: Start-up oscillator frequency is device-dependent. The UPDI will count for 65536 cycles on the UPDI clock
before issuing the time-out.
Incorrect SYNCH pattern
An incorrect SYNCH pattern is detected if the length of the SYNCH character is longer than the number of samples
that can be contained in the UPDI Baud Rate register (overflow), or shorter than the minimum fractional count that
can be handled for the sampling length of each bit. If any of these errors are detected, the UPDI will disable itself.
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32.3.2.2.2 UPDI Regular Disable
Any programming or debugging session that does not require any specific operation from the UPDI after
disconnecting the programmer has to be terminated by writing the UPDI Disable (UPDIDIS) bit in the Control B
(UPDI.CTRLB) register, upon which the UPDI will issue a System Reset and disable itself. The Reset will restore the
CPU to the Run state, independent of the previous state. It will also lower the UPDI clock request to the system and
reset any UPDI KEYs and settings.
If the disable operation is not performed, the UPDI and the oscillator’s request will remain enabled. This causes
increased power consumption for the application.
32.3.2.3 UPDI Communication Error Handling
The UPDI contains a comprehensive error detection system that provides information to the debugger when
recovering from an error scenario. The error detection consists of detecting physical transmission errors like parity
error, contention error, and frame error, to more high-level errors like access time-out error. See the UPDI Error
Signature (PESIG) bit field in the Status B (UPDI.STATUSB) register for an overview of the available error signatures.
Whenever the UPDI detects an error, it will immediately enter an internal Error state to avoid unwanted system
communication. In the Error state, the UPDI will ignore all incoming data requests, except when a BREAK character
is received. The following procedure must always be applied when recovering from an Error condition.
1. Send a BREAK character. See section BREAK Character for recommended BREAK character handling.
2. Send a SYNCH character at the desired baud rate for the next data transfer.
3. Execute a Load Control Status (LDCS) instruction to read the UPDI Error Signature (PESIG) bit field in the
Status B (UPDI.STATUSB) register and get the information about the occurred error.
4. The UPDI has now recovered from the Error state and is ready to receive the next SYNCH character and
instruction.
32.3.2.4 Direction Change
To ensure correct timing for a half-duplex UART operation, the UPDI has a built-in guard time mechanism to relax the
timing when changing direction from RX to TX mode. The guard time is represented by Idle bits inserted before the
next Start bit of the first response byte is transmitted. The number of Idle bits can be configured through the Guard
Time Value (GTVAL) bit field in the Control A (UPDI.CTRLA) register. The duration of each Idle bit is given by the
baud rate used by the current transmission.
Figure 32-6. UPDI Direction Change by Inserting Idle Bits
RX Data Frame
St
RX Data Frame
Dir Change
P
Data from
debugger to UPDI
S1
S2
IDLE bits
TX Data Frame
St
G uard Tim e #
IDLE bits inserted
TX Data Frame
P
S1
S2
Data from UPDI to
debugger
The UPDI guard time is the minimum Idle time that the connected debugger will experience when waiting for data
from the UPDI. The maximum Idle time is the same as time-out. The Idle time before a transmission will be more than
the expected guard time when the synchronization time plus the data bus accessing time is longer than the guard
time.
It is recommended to always use the insertion of minimum two Guard Time bits on the UPDI side, and one guard time
cycle insertion from the debugger side.
32.3.3
UPDI Instruction Set
The communication through the UPDI is based on a small instruction set. These instructions are part of the UPDI
Data Link (DL) layer. The instructions are used to access the UPDI registers, since they are mapped into an internal
memory space called “ASI Control and Status (CS) space”, as well as the memory-mapped system space. All
instructions are byte instructions and must be preceded by a SYNCH character to determine the baud rate for the
communication. See section UPDI UART for information about setting the baud rate for the transmission. The
following figure gives an overview of the UPDI instruction set.
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Figure 32-7. UPDI Instruction Set Overview
Opcode
LDS
STS
0
0
0
1
Size A
0
0
0
0
Opcode
LD
ST
0
0
0
1
Ptr
1
1
Size B
Size A/B
0
STCS
1
1
0
1
0
0
0
0
0
LDS
0
0
1
LD
0
1
0
STS
0
1
1
ST
1
0
0
LDCS (LDS Control/Status)
1
0
1
REPEAT
1
1
0
STCS (STS Control/Status)
1
1
1
KEY
Size A - Address Size
0
CS Address
LDCS
OPCODE
0
0
Byte - can address 0-255 B
0
1
Word (2 Bytes) - for memories up to 64 KB in size
1
0
3 Bytes - for memories above 64 KB in size
1
1
Reserved
Ptr - Pointer Access
0
0
0
0
* (ptr)
0
1
* (ptr++)
1
0
ptr
1
1
Reserved
Size B - Data Size
Size B
REPEAT
1
0
1
0
0
0
SIB
KEY
1
1
1
0
Size C
0
0
0
Byte
0
1
Word (2 Bytes)
1
0
Reserved
1
1
Reserved
CS Address (CS - Control/Status reg.)
Size C - Key Size
0
0
64 bits (8 Bytes)
0
1
128 bits (16 Bytes)
1
0
Reserved
1
1
Reserved
SIB - System Information Block Sel.
0
Receive KEY
1
Send SIB
32.3.3.1 LDS - Load Data from Data Space Using Direct Addressing
The LDS instruction is used to load data from the system bus into the PHY layer shift register for serial readout. The
LDS instruction is based on direct addressing, and the address must be given as an operand to the instruction for the
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data transfer to start. The maximum supported size for the address and data is 32 bits. The LDS instruction supports
repeated memory access when combined with the REPEAT instruction.
After issuing the LDS instruction, the number of desired address bytes, as indicated by the Size A field followed by
the output data size, which is selected by the Size B field, must be transmitted. The output data is issued after the
specified Guard Time (GT). When combined with the REPEAT instruction, the address must be sent in for each
iteration of the repeat, meaning after each time the output data sampling is done. There is no automatic address
increment when using REPEAT with LDS, as it uses a direct addressing protocol.
Figure 32-8. LDS Instruction Operation
OPCODE
Size A
Size B
Size A - Address Size
0
LDS
0
0
0
0
0
0
1
Word (2 Bytes) - for memories up to 64 KB in size
1
0
3 Bytes - for memories above 64 KB in size
1
1
Reserved
1 Byte - can address 0-255 B
Size B - Data Size
0
0
1 Byte
0
1
Word (2 Bytes)
1
0
Reserved
1
1
Reserved
ADDRESS_SIZE
Synch
(0x55)
LDS
Adr_0
RX
Adr_n
Data_0
Data_n
TX
ΔGT
When the instruction is decoded, and the address byte(s) are received as dictated by the decoded instruction, the DL
layer will synchronize all required information to the ACC layer, which will handle the bus request and synchronize
data buffered from the bus back again to the DL layer. This will create a synchronization delay that must be taken into
consideration upon receiving the data from the UPDI.
32.3.3.2 STS - Store Data to Data Space Using Direct Addressing
The STS instruction is used to store data that are shifted serially into the PHY layer shift register to the system bus
address space. The STS instruction is based on direct addressing, and the address must be given as an operand to
the instruction for the data transfer to start. The address is the first set of operands, and data are the second set. The
size of the address and data operands are given by the size fields presented in Figure 32-9. The maximum size for
both address and data is 32 bits.
The STS supports repeated memory access when combined with the REPEAT instruction.
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Figure 32-9. STS Instruction Operation
OPCODE
0
STS
1
Size A
0
Size B
Size A - Address Size
0
0
0
1 Byte - can address 0-255 B
0
1
Word (2 Bytes) - for memories up to 64 KB in size
1
0
3 Bytes - for memories above 64 KB in size
1
1
Reserved
Size B - Data Size
0
0
1 Byte
0
1
Word (2 Bytes)
1
0
Reserved
1
1
Reserved
ADDRESS_SIZE
Synch
(0x55)
STS
Adr_0
DATA_SIZE
Adr_n
Data_0
RX
Data_n
ACK
ΔGT
ACK
TX
ΔGT
The transfer protocol for an STS instruction is depicted in Figure 32-9, following this sequence:
1.
2.
3.
The address is sent.
An Acknowledge (ACK) is sent back from the UPDI if the transfer was successful.
The number of bytes, as specified in the STS instruction, is sent.
4.
A new ACK is received after the data have been successfully transferred.
32.3.3.3 LD - Load Data from Data Space Using Indirect Addressing
The LD instruction is used to load data from the data space and into the PHY layer shift register for serial readout.
The LD instruction is based on indirect addressing, which means that the Address Pointer in the UPDI needs to be
written before the data space read access. Automatic pointer post-increment operation is supported and is useful
when the LD instruction is utilized with the REPEAT instruction. It is also possible to do an LD from the UPDI Pointer
register. The maximum supported size for address and data load is 32 bits.
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Figure 32-10. LD Instruction Operation
OPCODE
LD
0
0
Ptr
1
Size A/B
Ptr - Pointer Access
0
Size A - Address Size
Synch
(0x55)
0
0
* ( ptr)
0
1
* (ptr++)
1
0
ptr
1
1
Reserved
Size B - Data Size
0
0
Byte - can address 0-255 B
0
0
Byte
0
1
Word (2 Bytes) - for memories up to 64 KB in size
0
1
Word (2 Bytes)
1
0
3 Bytes - for memories above 64 KB in size
1
0
Reserved
1
1
Reserved
1
1
Reserved
LD
DATA_SIZE
Data_0
RX
Data_n
TX
ΔGT
The figure above shows an example of a typical LD sequence, where the data are received after the Guard Time
(GT) period. Loading data from the UPDI Pointer register follows the same transmission protocol.
For the LD instruction from the data space, the pointer register must be set up by using an ST instruction to the UPDI
Pointer register. After the ACK has been received on a successful Pointer register write, the LD instruction must be
set up with the desired DATA SIZE operands. An LD to the UPDI Pointer register is done directly with the LD
instruction.
32.3.3.4 ST - Store Data from UPDI to Data Space Using Indirect Addressing
The ST instruction is used to store data from the UPDI PHY shift register to the data space. The ST instruction is
used to store data that are shifted serially into the PHY layer. The ST instruction is based on indirect addressing,
which means that the Address Pointer in the UPDI needs to be written before the data space. The automatic pointer
post-increment operation is supported and is useful when the ST instruction is utilized with the REPEAT instruction.
The ST instruction is also used to store the UPDI Address Pointer into the Pointer register. The maximum supported
size for storing address and data is 32 bits.
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Figure 32-11. ST Instruction Operation
OPCODE
ST
0
1
Ptr
1
Size A/B
Ptr - Pointer Access
0
0
0
* ( ptr)
0
1
* ( ptr++)
1
0
ptr
1
1
Reserved
Size A - Address Size
Size B - Data Size
0
0
Byte - can address 0-255 B
0
0
1 Byte
0
1
Word (2 Bytes) - for memories up to 64 KB in size
0
1
Word (2 Bytes)
1
0
3 Bytes - for memories above 64 KB in size
1
0
Reserved
1
1
Reserved
1
1
Reserved
ADDRESS_SIZE
Synch
(0x55)
ST
ADR_0
ADR_n
RX
ACK
TX
ΔGT
BLOCK_SIZE
Synch
(0x55)
ST
Data_0
RX
Data_n
ACK
TX
ΔGT
The figure above gives an example of an ST instruction to the UPDI Pointer register and the storage of regular data.
A SYNCH character is sent before each instruction. In both cases, an Acknowledge (ACK) is sent back by the UPDI if
the ST instruction was successful.
To write the UPDI Pointer register, the following procedure has to be followed:
1. Set the PTR field in the ST instruction to signature 0x2.
2.
3.
Set the address size (Size A) field to the desired address size.
After issuing the ST instruction, send Size A bytes of address data.
4.
Wait for the ACK character, which signifies a successful write to the Address register.
After the Address register is written, sending data is done in a similarly:
1. Set the PTR field in the ST instruction to signature 0x0 to write to the address specified by the UPDI Pointer
register. If the PTR field is set to 0x1, the UPDI pointer is automatically updated to the next address according
to the data size Size B field of the instruction after the write is executed.
2. Set the Size B field in the instruction to the desired data size.
3. After sending the ST instruction, send Size B bytes of data.
4.
Wait for the ACK character, which signifies a successful write to the bus matrix.
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When used with the REPEAT instruction, it is recommended to set up the Address register with the start address for
the block to be written and use the Pointer Post Increment register to automatically increase the address for each
repeat cycle. When using the REPEAT instruction, the data frame of Size B data bytes can be sent after each
received ACK.
32.3.3.5 LDCS - Load Data from Control and Status Register Space
The LDCS instruction is used to load serial readout data from the UPDI Control and the Status register space located
in the DL layer into the PHY layer shift register. The LDCS instruction is based on direct addressing, where the
address is part of the instruction operands. The LDCS instruction can access only the UPDI CS register space. This
instruction supports only byte access, and the data size is not configurable.
Figure 32-12. LDCS Instruction Operation
OPCODE
LDCS
1
0
CS Address
0
CS Address ( CS - Control/Status reg.)
0
Synch
(0x55)
LDCS
RX
Data
TX
Δgt
Figure 32-12 shows a typical example of LDCS data transmission. A data byte from the LDCS is transmitted from the
UPDI after the guard time is completed.
32.3.3.6 STCS - Store Data to Control and Status Register Space
The STCS instruction is used to store data to the UPDI Control and Status register space. Data are shifted in serially
into the PHY layer shift register and written as a whole byte to a selected CS register. The STCS instruction is based
on direct addressing, where the address is part of the instruction operand. The STCS instruction can access only the
internal UPDI register space. This instruction supports only byte access, and the data size is not configurable.
Figure 32-13. STCS Instruction Operation
OPCODE
STCS
1
1
CS Address
0
CS Address ( CS - Control/Status reg.)
0
Synch
(0x55)
STCS
Data
RX
TX
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Figure 32-13 shows the data frame transmitted after the SYNCH character and the instruction frames. The STCS
instruction byte can be immediately followed by the data byte. There is no response generated from the STCS
instruction, as is the case for the ST and STS instructions.
32.3.3.7 REPEAT - Set Instruction Repeat Counter
The REPEAT instruction is used to store the repeat count value into the UPDI Repeat Counter register on the DL
layer. When instructions are used with REPEAT, the protocol overhead for SYNCH and instruction frame can be
omitted on all instructions except the first instruction after the REPEAT is issued. REPEAT is most useful for memory
instructions (LD, ST, LDS, STS), but all instructions can be repeated, except for the REPEAT instruction itself.
The DATA_SIZE operand field refers to the size of the repeat value. Only up to 255 repeats are supported. The
instruction loaded directly after the REPEAT instruction will be issued for RPT_0 + 1 times. If the Repeat Counter
register is ‘0’, the instruction will run just once. An ongoing repeat can be aborted only by sending a BREAK
character.
Figure 32-14. REPEAT Instruction Operation used with ST Instruction
OPCODE
REPEAT
1
0
Size B
1
0
0
0
Size B - Data Size
0
0
1 Byte
0
1
Word (2 Bytes)
1
0
Reserved
1
1
Reserved
REPEAT_SIZE
Synch
(0x55)
REPEAT
RPT_0
Repeat Number of Blocks of DATA_SIZE
DATA_SIZE
Synch
(0x55)
ST
(ptr++)
Data_0
Data_n
DATA_SIZE
DATA_SIZE
DataB_1
DataB_n
RX
ACK
Δd
ACK
Δd
Δd
Δd
TX
Δd
Figure 32-14 gives an example of a repeat operation with an ST instruction using pointer post-increment operation.
After the REPEAT instruction is sent with RPT_0 = n, the first ST instruction is issued with SYNCH and instruction
frame, while the next n ST instructions are executed by only sending data bytes according to the ST operand
DATA_SIZE, and maintaining the Acknowledge (ACK) handshake protocol.
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Figure 32-15. REPEAT used with LD Instruction
REPEAT_SIZE
Synch
(0x55)
Synch
(0x55)
RPT_0
REPEAT
RPT_1
LD
(ptr++)
RX
Repeat Number of Blocks of DATA_SIZE
DATA_SIZE
DATA_SIZE
DataB_1
DataB_n
TX
ΔGT
For LD, data will come out continuously after the LD instruction. Note the guard time on the first data block.
If using indirect addressing instructions (LD/ST), it is recommended to always use the pointer post-increment option
when combined with REPEAT. The ST/LD instruction is necessary only before the first data block (number of data
bytes determined by DATA_SIZE). Otherwise, the same address will be accessed in all repeated access operations.
For direct addressing instructions (LDS/STS), the address must always be transmitted as specified in the instruction
protocol, before data can be received (LDS) or sent (STS).
32.3.3.8 KEY - Set Activation Key or Send System Information Block
The KEY instruction is used for communicating key bytes to the UPDI or for providing the programmer with a System
Information Block (SIB), opening up for executing protected features on the device. See Key Activation Overview for
an overview of functions that are activated by keys. For the KEY instruction, only a 64-bit key size is supported. The
maximum supported size for SIB is 128 bits.
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Figure 32-16. KEY Instruction Operation
SIB
KEY
1
1
1
0
Size C
0
Size C - Key Size
0
0
0
1 128 bits (16 Bytes) (SIB only)
64 bits (8 Bytes)
1
0
Reserved
1
1
Reserved
SIB - System Information Block Sel.
0
Send KEY
1
Receive SIB
KEY_SIZE
Synch
(0x55)
KEY
KEY_0
KEY_n
RX
TX
Synch
(0x55)
RX
KEY
SIB_0
Δgt
SIB_n
TX
SIB_SIZE
Figure 32-16 shows the transmission of a key and the reception of a SIB. In both cases, the Size C (SIZE_C) field in
the operand determines the number of frames being sent or received. There is no response after sending a KEY to
the UPDI. When requesting the SIB, data will be transmitted from the UPDI according to the current guard time
setting.
32.3.4
CRC Checking of Flash During Boot
Some devices support running a CRC check of the Flash contents as part of the boot process. This check can be
performed even when the device is locked. The result of this CRC check can be read from the ASI_CRC_STATUS
register. Refer to the CRCSCAN section in the device data sheet for more information on this feature.
32.3.5
System Clock Measurement with UPDI
It is possible to use the UPDI to get an accurate measurement of the system clock frequency by utilizing the UPDI
event connected to TCB with Input Capture capabilities. A recommended setup flow for this feature is given by the
following steps:
• Set up TCBn.CTRLB with setting CNTMODE = 0x3, Input Capture Frequency Measurement mode
•
Write CAPTEI = 1 in TCBn.EVCTRL to enable Event Interrupt. Keep EDGE = 0 in TCBn.EVCTRL
•
•
Configure the Event System to route the UPDI SYNCH event (generator) to the TCB (user)
For the SYNCH character used to generate the UPDI events, it is recommended to use a slow baud rate in the
range of 10-50 kbps to get a more accurate measurement of the value captured by the timer between each
UPDI event. One particular thing is that if the capture is set up to trigger an interrupt, the first captured value
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•
must be ignored. The second captured value based on the input event must be used for the measurement. See
Figure 32-17 for an example using 10 kbps UPDI SYNCH character pulses, giving a capture window of 200 µs
for the timer.
It is possible to read out the captured value directly after the SYNCH character by reading the TCBn.CCMP
register, or the value can be written to memory by the CPU once the capture is done. For more details, refer to
the TCB - 16-bit Timer/Counter Type B section.
Figure 32-17. UPDI System Clock Measurement Events
Ignore the first
capture event
200 μs
UPDI_Input
TCB_CCMP
32.3.6
CAPT_1
CAPT_2
CAPT_3
Inter-Byte Delay
When performing a multibyte transfer (LD combined with REPEAT), or reading out the System Information Block
(SIB), the output data will come out in a continuous stream. Depending on the application, on the receiver side, the
data might come out too fast, and there might not be enough time for the data to be processed before the next Start
bit arrives.
The inter-byte delay works by inserting a fixed number of Idle bits for multibyte transfers. The reason for adding an
inter-byte delay is that there is no guard time inserted when all data is going in the same direction.
The inter-byte delay feature can be enabled by writing a ‘1’ to the Inter-Byte Delay Enable (IBDLY) bit in the Control A
(UPDI.CTRLA) register. As a result, two extra Idle bits will be inserted between each byte to relax the sampling time
for the debugger.
Figure 32-18. Inter-Byte Delay Example with LD and RPT
Too Fast Transmission, no Inter-Byte Delay
RX
Debugger
Data
TX
RPT
CNT
LD*(ptr)
GT
Debugger
Processing
D0
SB D1 SB
D0
D2 SB
D1 lost
D3
SB
D3 lost
D2
D4 SB
D5
SB
D4
Data Sampling OK with Inter-Byte Delay
RX
Debugger
Data
TX
RPT
CNT
Debugger
Processing
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LD*(ptr)
GT
D0 SB IB
D0
SB IB
D1
D1
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SB IB
D2
D3
SB
D3
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Notes:
1. GT denotes the guard time insertion.
2. SB is for Stop bit.
3. IB is the inserted inter-byte delay.
4. The rest of the frames are data and instructions.
32.3.7
System Information Block
The System Information Block (SIB) can be read out at any time by setting the SIB bit according to the KEY
instruction from 32.3.3.8 KEY - Set Activation Key or Send System Information Block. The SIB is always accessible
to the debugger, regardless of lock bit settings, and provides a compact form of supplying information about the
device and system parameters for the debugger. The information is vital in identifying and setting up the proper
communication channel with the device. The output of the SIB is interpreted as ASCII symbols. The key size field
must be set to 16 bytes when reading out the complete SIB, and an 8-byte size can be used to read out only the
Family_ID. See Figure 32-19 for SIB format description and which data are available at different readout sizes.
Figure 32-19. System Information Block Format
16 8
32.3.8
[Byte][Bits]
[6:0] [55:0]
[7][7:0]
[10:8][23:0]
[13:11][23:0]
[14][7:0]
[15][7:0]
Field Name
Family_ID
Reserved
NVM_VERSION
OCD_VERSION
RESERVED
DBG_OSC_FREQ
Enabling of Key Protected Interfaces
The access to some internal interfaces and features is protected by the UPDI key mechanism. To activate a key, the
correct key data must be transmitted by using the KEY instruction, as described in 32.3.3.8 KEY - Set Activation Key
or Send System Information Block. Table 32-4 describes the available keys and the condition required when doing
the operation with the key active.
Table 32-4. Key Activation Overview
Key Name
Description
Requirements for Operation
Chip Erase
Start NVM chip erase.
Clear lock bits
NVMPROG
Activate NVM
Programming
Lock bits cleared.
ASI_SYS_STATUS.NVMPROG set
USERROW-Write
Program the user row
on the locked device
Lock bits set.
Write to key Status bit/
ASI_SYS_STATUS.UROWPROG set UPDI Reset
-
Conditions for Key
Invalidation
UPDI Disable/UPDI Reset
Programming done/UPDI
Reset
Table 32-5 gives an overview of the available key signatures that must be shifted in to activate the interfaces.
Table 32-5. Key Activation Signatures
Key Name
Key Signature (LSB Written First)
Size
Chip Erase
0x4E564D4572617365
64 bits
NVMPROG
0x4E564D50726F6720
64 bits
USERROW-Write
0x4E564D5573267465
64 bits
32.3.8.1 Chip Erase
The following steps should be followed to issue a chip erase:
1. Enter the Chip Erase key by using the KEY instruction. See Table 32-5 for the CHIPERASE signature.
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2.
3.
4.
5.
6.
Optional: Read the Chip Erase (CHIPERASE) bit in the ASI Key Status (UPDI.ASI_KEY_STATUS) register to
see that the key is successfully activated.
Write the signature to the Reset Request (RSTREQ) bit in the ASI Reset Request (UPDI.ASI_RESET_REQ)
register. This will issue a System Reset.
Write 0x00 to the ASI Reset Request (UPDI.ASI_RESET_REQ) register to clear the System Reset.
Read the NVM Lock Status (LOCKSTATUS) bit from the ASI System Status (UPDI.ASI_SYS_STATUS)
register.
The chip erase is done when LOCKSTATUS bit is ‘0’. If the LOCKSTATUS bit is ‘1’, return to step 5.
After a successful Chip Erase, the Lockbits will be cleared, and the UPDI will have full access to the system. Until
Lockbits are cleared, the UPDI cannot access the system bus, and only CS-space operations can be performed.
CAUTION
During chip erase, the BOD is forced in ON state by writing to the Active (ACTIVE) bit field from the
Control A (BOD.CTRLA) register and uses the BOD Level (LVL) bit field from the BOD Configuration
(FUSE.BODCFG) fuse and the BOD Level (LVL) bit field from the Control B (BOD.CTRLB) register. If the
supply voltage VDD is below that threshold level, the device is unavailable until VDD is increased
adequately. See the BOD section for more details.
32.3.8.2 NVM Programming
If the device is unlocked, it is possible to write directly to the NVM Controller or to the Flash memory using the UPDI.
This will lead to unpredictable code execution if the CPU is active during the NVM programming. To avoid this, the
following NVM Programming sequence has to be executed.
1.
2.
3.
4.
5.
6.
7.
Follow the chip erase procedure, as described in Chip Erase. If the part is already unlocked, this point can be
skipped.
Enter the NVMPROG key by using the KEY instruction. See Table 32-5 for the NVMPROG signature.
Optional: Read the NVM Programming Key Status (NVMPROG) bit from the ASI Key Status
(UPDI.KEY_STATUS) register to see if the key has been activated.
Write the signature to the Reset Request (RSTREQ) bit in the ASI Reset Request (UPDI.ASI_RESET_REQ)
register. This will issue a System Reset.
Write 0x00 to the ASI Reset Request (UPDI.ASI_RESET_REQ) register to clear the System Reset.
Read the NVM Programming Key Status (NVMPROG) bit from the ASI System Status
(UPDI.ASI_SYS_STATUS) register.
NVM Programming can start when the NVMPROG bit is ‘1’. If the NVMPROG bit is ‘0’, return to step 6.
8.
9.
Write data to NVM through the UPDI.
Write the signature to the Reset Request (RSTREQ) bit in the ASI Reset Request (UPDI.ASI_RESET_REQ)
register. This will issue a System Reset.
10. Write 0x00 to the ASI Reset Request (UPDI.ASI_RESET_REQ) register to clear the System Reset.
11. Programming is complete.
32.3.8.3 User Row Programming
The User Row Programming feature allows programming new values to the user row (USERROW) on a locked
device. To program with this functionality enabled, the following sequence must be followed:
1.
2.
3.
4.
5.
6.
Enter the USERROW-Write key located in Table 32-5 by using the KEY instruction. See Table 32-5 for the
USERROW-Write signature.
Optional: Read the User Row Write Key Status (UROWWRITE) bit from the ASI Key Status
(UPDI.ASI_KEY_STATUS) register to see if the key has been activated.
Write the signature to the Reset Request (RSTREQ) bit in the ASI Reset Request (UPDI.ASI_RESET_REQ)
register. This will issue a System Reset.
Write 0x00 to the ASI Reset Request (UPDI.ASI_RESET_REQ) register to clear the System Reset.
Read the Start User Row Programming (UROWPROG) bit from the ASI System Status
(UPDI.ASI_SYS_STATUS) register.
User Row Programming can start when the UROWPROG bit is ‘1’. If UROWPROG is ‘0’, return to step 5.
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7.
8.
9.
10.
11.
12.
13.
The data to be written to the User Row must first be written to a buffer in the RAM. The writable area in the
RAM has a size of 32 bytes, and it is only possible to write user row data to the first 32 byte addresses of the
RAM. Addressing outside this memory range will result in a nonexecuted write. The data will map 1:1 with the
user row space when the data is copied into the user row upon completion of the Programming sequence.
When all user row data has been written to the RAM, write the User Row Programming Done (UROWDONE)
bit in the ASI System Control A (UPDI.ASI_SYS_CTRLA) register.
Read the Start User Row Programming (UROWPROG) bit from the ASI System Status
(UPDI.ASI_SYS_STATUS) register.
The User Row Programming is completed when UROWPROG bit is ‘0’. If UROWPROG bit is ‘1’, return to step
9.
Write to the User Row Write Key Status (UROWWRITE) bit in the ASI Key Status (UPDI.ASI_KEY_STATUS)
register.
Write the signature to the Reset Request (RSTREQ) bit in the ASI Reset Request (UPDI.ASI_RESET_REQ)
register. This will issue a System Reset.
Write 0x00 to the ASI Reset Request (UPDI.ASI_RESET_REQ) register to clear the System Reset.
14. The User Row Programming is complete.
It is not possible to read back data from the RAM in this mode. Only writes to the first 32 bytes of the RAM are
allowed.
32.3.9
Events
The UPDI can generate the following events:
Table 32-6. Event Generators in UPDI
Generator Name
Module
Event
UPDI
SYNCH
Description
SYNCH
character
Event Type
Level
Generating
Clock
Domain
CLK_UPDI
Length of Event
SYNCH char on UPDI pin
synchronized to CLK_UPDI
This event is set on the UPDI clock for each detected positive edge in the SYNCH character, and it is not possible to
disable this event from the UPDI.
The UPDI has no event users.
Refer to the Event System section for more details regarding event types and Event System configuration.
32.3.10 Sleep Mode Operation
The UPDI PHY layer runs independently of all sleep modes, and the UPDI is always accessible for a connected
debugger independent of the device’s sleep state. If the system enters a sleep mode that turns the system clock off,
the UPDI will not be able to access the system bus and read memories and peripherals. When enabled, the UPDI will
request the system clock so that the UPDI always has contact with the rest of the device. Thus, the UPDI PHY layer
clock is unaffected by the sleep mode’s settings. By reading the System Domain in Sleep (INSLEEP) bit in the ASI
System Status (UPDI.ASI_SYS_STATUS) register, it is possible to monitor if the system domain is in a sleep mode.
It is possible to prevent the system clock from stopping when going into a sleep mode, by writing to the Request
System Clock (CLKREQ) bit in the ASI System Control A (UPDI.ASI_SYS_CTRLA) register. If this bit is set, the
system sleep mode state is emulated, and the UPDI can access the system bus and read the peripheral registers
even in the deepest sleep modes.
The CLKREQ bit is by default ‘1’ when the UPDI is enabled, which means that the default operation is keeping the
system clock in ON state during the sleep modes.
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32.4
Register Summary
Offset
Name
Bit Pos.
0x00
0x01
0x02
0x03
0x04
...
0x06
0x07
0x08
0x09
STATUSA
STATUSB
CTRLA
CTRLB
7:0
7:0
7:0
7:0
ASI_KEY_STATUS
ASI_RESET_REQ
ASI_CTRLA
7:0
7:0
7:0
0x0A
ASI_SYS_CTRLA
7:0
0x0B
0x0C
ASI_SYS_STATUS
ASI_CRC_STATUS
7:0
7:0
32.5
7
6
5
4
3
DTD
NACKDIS
RSD
CCDETDIS
2
1
0
UPDIREV[3:0]
IBDLY
PARD
PESIG[2:0]
GTVAL[2:0]
UPDIDIS
Reserved
UROWWRITE NVMPROG CHIPERASE
RSTREQ[7:0]
RSTSYS
INSLEEP
UPDICLKSEL[1:0]
UROWWRITE
CLKREQ
_FINAL
NVMPROG UROWPROG
LOCKSTATUS
CRC_STATUS[2:0]
Register Description
These registers are readable only through the UPDI with special instructions and are not readable through the CPU.
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32.5.1
Status A
Name:
Offset:
Reset:
Property:
Bit
7
STATUSA
0x00
0x20
-
6
5
4
R
1
R
0
3
2
1
0
UPDIREV[3:0]
Access
Reset
R
0
R
0
Bits 7:4 – UPDIREV[3:0] UPDI Revision
This bit field contains the revision of the current UPDI implementation.
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32.5.2
Status B
Name:
Offset:
Reset:
Property:
Bit
7
STATUSB
0x01
0x00
-
6
5
4
3
Access
Reset
2
R
0
1
PESIG[2:0]
R
0
0
R
0
Bits 2:0 – PESIG[2:0] UPDI Error Signature
This bit field describes the UPDI error signature and is set when an internal UPDI Error condition occurs. The PESIG
bit field is cleared on a read from the debugger.
Table 32-7. Valid Error Signatures
PESIG[2:0]
Error Type
Error Description
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
No error
Parity error
Frame error
Access Layer Time-Out Error
Clock Recovery error
Bus error
Contention error
No error detected (Default)
Wrong sampling of the Parity bit
Wrong sampling of the Stop bits
UPDI can get no data or response from the Access layer
Wrong sampling of the Start bit
Reserved
Address error or access privilege error
Signalize Driving Contention on the UPDI pin
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32.5.3
Control A
Name:
Offset:
Reset:
Property:
Bit
Access
Reset
7
IBDLY
R/W
0
CTRLA
0x02
0x00
-
6
5
PARD
R/W
0
4
DTD
R/W
0
3
RSD
R/W
0
2
R/W
0
1
GTVAL[2:0]
R/W
0
0
R/W
0
Bit 7 – IBDLY Inter-Byte Delay Enable
Writing a ‘1’ to this bit enables a fixed-length inter-byte delay between each data byte transmitted from the UPDI
when doing multibyte LD(S). The fixed length is two IDLE bits.
Bit 5 – PARD Parity Disable
Writing a ‘1’ to this bit will disable the parity detection in the UPDI by ignoring the Parity bit. This feature is
recommended to be used only during testing.
Bit 4 – DTD Disable Time-Out Detection
Writing a ‘1’ to this bit will disable the time-out detection on the PHY layer, which requests a response from the ACC
layer within a specified time (65536 UPDI clock cycles).
Bit 3 – RSD Response Signature Disable
Writing a ‘1’ to this bit will disable any response signatures generated by the UPDI. This reduces the protocol
overhead to a minimum when writing large blocks of data to the NVM space. When accessing the system bus, the
UPDI may experience delays. If the delay is predictable, the response signature may be disabled. Otherwise, a loss
of data may occur.
Bits 2:0 – GTVAL[2:0] Guard Time Value
This bit field selects the guard time value that will be used by the UPDI when the transmission direction switches from
RX to TX.
Value
Description
0x0
UPDI guard time: 128 cycles (default)
0x1
UPDI guard time: 64 cycles
0x2
UPDI guard time: 32 cycles
0x3
UPDI guard time: 16 cycles
0x4
UPDI guard time: 8 cycles
0x5
UPDI guard time: 4 cycles
0x6
UPDI guard time: 2 cycles
0x7
Reserved
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32.5.4
Control B
Name:
Offset:
Reset:
Property:
Bit
7
CTRLB
0x03
0x00
-
6
Access
Reset
5
4
NACKDIS
R/W
0
3
CCDETDIS
R/W
0
2
UPDIDIS
R/W
0
1
0
Bit 4 – NACKDIS Disable NACK Response
Writing a ‘1’ to this bit disables the NACK signature sent by the UPDI when a System Reset is issued during ongoing
LD(S) and ST(S) operations.
Bit 3 – CCDETDIS Collision and Contention Detection Disable
Writing a ‘1’ to this bit disables the contention detection. Writing a ‘0’ to this bit enables the contention detection.
Bit 2 – UPDIDIS UPDI Disable
Writing a ‘1’ to this bit disables the UPDI PHY interface. The clock request from the UPDI is lowered, and the UPDI is
reset. All the UPDI PHY configurations and keys will be reset when the UPDI is disabled.
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32.5.5
ASI Key Status
Name:
Offset:
Reset:
Property:
Bit
7
ASI_KEY_STATUS
0x07
0x00
-
6
Access
Reset
5
UROWWRITE
R/W
0
4
NVMPROG
R
0
3
CHIPERASE
R
0
2
1
0
Bit 5 – UROWWRITE User Row Write Key Status
This bit is set to ‘1’ if the UROWWRITE key is successfully decoded. This bit must be written as the final part of the
user row write procedure to correctly reset the programming session.
Bit 4 – NVMPROG NVM Programming Key Status
This bit is set to ‘1’ if the NVMPROG key is successfully decoded. The bit is cleared when the NVM Programming
sequence is initiated, and the NVMPROG bit in ASI_SYS_STATUS is set.
Bit 3 – CHIPERASE Chip Erase Key Status
This bit is set to ‘1’ if the Chip Erase key is successfully decoded. The bit is cleared by the Reset Request issued as
part of the Chip Erase sequence described in the Chip Erase section.
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32.5.6
ASI Reset Request
Name:
Offset:
Reset:
Property:
ASI_RESET_REQ
0x08
0x00
-
A Reset is signalized to the System when writing the Reset signature to this register.
Bit
Access
Reset
7
6
5
R/W
0
R/W
0
R/W
0
4
3
RSTREQ[7:0]
R/W
R/W
0
0
2
1
0
R/W
0
R/W
0
R/W
0
Bits 7:0 – RSTREQ[7:0] Reset Request
The UPDI will not be reset when issuing a System Reset from this register.
Value
Name
Description
0x00
RUN
Clear Reset condition
0x59
RESET
Normal Reset
Other
Reserved
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32.5.7
ASI Control A
Name:
Offset:
Reset:
Property:
Bit
7
ASI_CTRLA
0x09
0x03
-
6
5
4
3
Access
Reset
2
1
0
UPDICLKSEL[1:0]
R/W
R/W
1
1
Bits 1:0 – UPDICLKSEL[1:0] UPDI Clock Divider Select
Writing these bits selects the UPDI clock output frequency. The default setting after Reset and enable is 4 MHz. Any
other clock output selection is only recommended when the BOD is at the highest level. For all other BOD settings,
the default 4 MHz selection is recommended.
Value
Description
0x0
Reserved
0x1
16 MHz UPDI clock
0x2
8 MHz UPDI clock
0x3
4 MHz UPDI clock (Default Setting)
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32.5.8
ASI System Control A
Name:
Offset:
Reset:
Property:
ASI_SYS_CTRLA
0x0A
0x00
-
Bit
7
6
5
4
3
2
Access
Reset
R
0
R
0
R
0
R
0
R
0
R
0
1
UROWWRITE_
FINAL
R/W
0
0
CLKREQ
R/W
0
Bit 1 – UROWWRITE_FINAL User Row Programming Done
This bit must be written when the user row data have been written to the RAM. Writing a ‘1’ to this bit will start the
process of programming the user row data to the Flash.
If this bit is written before the user row data is written to the RAM by the UPDI, the CPU will proceed without the
written data.
This bit is writable only if the USERROW-Write key is successfully decoded.
Bit 0 – CLKREQ Request System Clock
If this bit is written to ‘1’, the ASI is requesting the system clock, independent of the system sleep modes. This makes
it possible for the UPDI to access the ACC layer, also if the system is in a sleep mode.
Writing a ‘0’ to this bit will lower the clock request.
This bit will be reset when the UPDI is disabled.
This bit is set by default when the UPDI is enabled in any programming mode (Fuse, high-voltage).
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32.5.9
ASI System Status
Name:
Offset:
Reset:
Property:
Bit
7
ASI_SYS_STATUS
0x0B
0x01
-
6
Access
Reset
5
RSTSYS
R
0
4
INSLEEP
R
0
3
NVMPROG
R
0
2
UROWPROG
R
0
1
0
LOCKSTATUS
R
1
Bit 5 – RSTSYS System Reset Active
When this bit is set to ‘1’, there is an active Reset on the system domain. When this bit is set to ‘0’, the system is not
in the Reset state.
This bit is set to ‘0’ on read.
A Reset held from the ASI_RESET_REQ register will also affect this bit.
Bit 4 – INSLEEP System Domain in Sleep
When this bit is set to ‘1’, the system domain is in Idle or deeper Sleep mode. When this bit is set to ‘0’, the system is
not in any sleep mode.
Bit 3 – NVMPROG Start NVM Programming
When this bit is set to ‘1’, NVM Programming can start from the UPDI.
When the programming is complete, reset the system through the UPDI Reset register.
Bit 2 – UROWPROG Start User Row Programming
When this bit is set to ‘1’, User Row Programming can start from the UPDI.
When the User Row data have been written to the RAM, the UROWDONE bit in the ASI_SYS_CTRLA register must
be written.
Bit 0 – LOCKSTATUS NVM Lock Status
When this bit is set to ‘1’, the device is locked. If a chip erase is done, and the lock bits are set to ‘0’, this bit will be
read as ‘0’.
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32.5.10 ASI CRC Status
Name:
Offset:
Reset:
Property:
Bit
7
ASI_CRC_STATUS
0x0C
0x00
-
6
5
4
3
Access
Reset
2
R
0
1
CRC_STATUS[2:0]
R
0
0
R
0
Bits 2:0 – CRC_STATUS[2:0] CRC Execution Status
This bit field signalizes the status of the CRC conversion. This bit field is one-hot encoded.
Value
Description
0x0
Not enabled
0x1
CRC enabled, busy
0x2
CRC enabled, done with OK signature
0x4
CRC enabled, done with FAILED signature
Other
Reserved
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Instruction Set Summary
33.
Instruction Set Summary
The instruction set summary is part of the AVR Instruction Set Manual, located at www.microchip.com/DS40002198.
Refer to the CPU version called AVRxt, for details regarding the devices documented in this data sheet.
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Conventions
34.
Conventions
34.1
Numerical Notation
Table 34-1. Numerical Notation
34.2
Symbol
Description
165
Decimal number
0b0101
Binary number
‘0101’
Binary numbers are given without prefix if unambiguous
0x3B24
Hexadecimal number
X
Represents an unknown or do not care value
Z
Represents a high-impedance (floating) state for either a
signal or a bus
Memory Size and Type
Table 34-2. Memory Size and Bit Rate
34.3
Symbol
Description
KB
kilobyte (210B = 1024B)
MB
megabyte (220B = 1024 KB)
GB
gigabyte (230B = 1024 MB)
b
bit (binary ‘0’ or ‘1’)
B
byte (8 bits)
1 kbit/s
1,000 bit/s rate
1 Mbit/s
1,000,000 bit/s rate
1 Gbit/s
1,000,000,000 bit/s rate
word
16-bit
Frequency and Time
Table 34-3. Frequency and Time
Symbol
Description
kHz
1 kHz = 103 Hz = 1,000 Hz
MHz
1 MHz = 106 Hz = 1,000,000 Hz
GHz
1 GHz = 109 Hz = 1,000,000,000 Hz
ms
1 ms = 10-3s = 0.001s
µs
1 µs = 10-6s = 0.000001s
ns
1 ns = 10-9s = 0.000000001s
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Conventions
34.4
Registers and Bits
Table 34-4. Register and Bit Mnemonics
Symbol
Description
R/W
Read/Write accessible register bit. The user can read from and write to this bit.
R
Read-only accessible register bit. The user can only read this bit. Writes will be ignored.
W
Write-only accessible register bit. The user can only write this bit. Reading this bit will return an
undefined value.
BITFIELD
Bitfield names are shown in uppercase. Example: INTMODE.
BITFIELD[n:m]
A set of bits from bit n down to m. Example: PINA[3:0] = {PINA3, PINA2, PINA1, PINA0}.
Reserved
Reserved bits, bit fields, and bit field values are unused and reserved for future use. For
compatibility with future devices, always write reserved bits to ‘0’ when the register is written.
Reserved bits will always return zero when read.
PERIPHERALn
If several instances of the peripheral exist, the peripheral name is followed by a single number to
identify one instance. Example: USARTn is the collection of all instances of the USART module,
while USART3 is one specific instance of the USART module.
PERIPHERALx
If several instances of the peripheral exist, the peripheral name is followed by a single capital
letter (A-Z) to identify one instance. Example: PORTx is the collection of all instances of the
PORT module, while PORTB is one specific instance of the PORT module.
Reset
Value of a register after a Power-on Reset. This is also the value of registers in a peripheral after
performing a software Reset of the peripheral, except for the Debug Control registers.
SET/CLR/TGL
Registers with SET/CLR/TGL suffix allow the user to clear and set bits in a register without doing
a read-modify-write operation.
Each SET/CLR/TGL register is paired with the register it is affecting. Both registers in a register
pair return the same value when read.
Example: In the PORT peripheral, the OUT and OUTSET registers form such a register pair. The
contents of OUT will be modified by a write to OUTSET. Reading OUT and OUTSET will return
the same value.
Writing a ‘1’ to a bit in the CLR register will clear the corresponding bit in both registers.
Writing a ‘1’ to a bit in the SET register will set the corresponding bit in both registers.
Writing a ‘1’ to a bit in the TGL register will toggle the corresponding bit in both registers.
34.4.1
Addressing Registers from Header Files
In order to address registers in the supplied C header files, the following rules apply:
1.
2.
3.
4.
A register is identified by ., e.g., CPU.SREG, USART2.CTRLA,
or PORTB.DIR.
The peripheral name is given in the “Peripheral Address Map” in the “Peripherals and Architecture” section.
is obtained by substituting any n or x in the peripheral name with the correct
instance identifier.
When assigning a predefined value to a peripheral register, the value is constructed following the rule:
___gc
is , but remove any instance identifier.
can be found in the “Name” column in the tables in the Register Description sections
describing the bit fields of the peripheral registers.
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Conventions
Example 34-1. Register Assignments
// EVSYS channel 0 is driven by TCB3 OVF event
EVSYS.CHANNEL0 = EVSYS_CHANNEL0_TCB3_OVF_gc;
// USART0 RXMODE uses Double Transmission Speed
USART0.CTRLB = USART_RXMODE_CLK2X_gc;
Note: For peripherals with different register sets in different modes, and
must be followed by a mode name, for example:
// TCA0 in Normal Mode (SINGLE) uses waveform generator in frequency mode
TCA0.SINGLE.CTRL=TCA_SINGLE_WGMODE_FRQ_gc;
34.5
ADC Parameter Definitions
An ideal n-bit single-ended ADC converts a voltage linearly between GND and VREF in 2n steps (LSb). The lowest
code is read as ‘0’, and the highest code is read as ‘2n-1’. Several parameters describe the deviation from the ideal
behavior:
Offset Error
The deviation of the first transition (0x000 to 0x001) compared to the ideal transition (at 0.5
LSb). Ideal value: 0 LSb.
Figure 34-1. Offset Error
Output Code
Ideal ADC
Actual ADC
Offset
Error
Gain Error
VREF Input Voltage
After adjusting for offset, the gain error is found as the deviation of the last transition (e.g.,
0x3FE to 0x3FF for a 10-bit ADC) compared to the ideal transition (at 1.5 LSb below
maximum). Ideal value: 0 LSb.
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Conventions
Figure 34-2. Gain Error
Gain
Error
Output Code
Ideal ADC
Actual ADC
VREF
Integral
Nonlinearity (INL)
Input Voltage
After adjusting for offset and gain error, the INL is the maximum deviation of an actual
transition compared to an ideal transition for any code. Ideal value: 0 LSb.
Figure 34-3. Integral Nonlinearity
Output Code
INL
Ideal ADC
Actual ADC
VREF
Differential
Nonlinearity (DNL)
Input Voltage
The maximum deviation of the actual code width (the interval between two adjacent
transitions) from the ideal code width (1 LSb). Ideal value: 0 LSb.
Figure 34-4. Differential Nonlinearity
Output Code
0x3FF
1 LSb
DNL
0x000
0
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VREF
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Input Voltage
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Conventions
Quantization Error
Due to the quantization of the input voltage into a finite number of codes, a range of input
voltages (1 LSb wide) will code to the same value. Always ±0.5 LSb.
Absolute Accuracy The maximum deviation of an actual (unadjusted) transition compared to an ideal transition
for any code. This is the compound effect of all errors mentioned before. Ideal value: ±0.5
LSb.
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Electrical Characteristics
35.
Electrical Characteristics
35.1
Disclaimer
All typical values are measured at T = 25°C and VDD = 3V unless otherwise specified. All minimum and maximum
values are valid across operating temperature and voltage unless otherwise specified.
35.2
Absolute Maximum Ratings
Stresses beyond those listed in this section may cause permanent damage to the device. This is a stress rating only
and functional operation of the device at these or other conditions beyond those indicated in the operational sections
of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Table 35-1. Absolute Maximum Ratings
Symbol Description
VDD
Power supply voltage
IVDD
Current into a VDD pin
IGND
Conditions
Current out of a GND pin
Min. Max.
Unit
-0.5 6
V
T = [-40, 85]°C
-
200
mA
T = [85, 125]°C
-
100
mA
T = [-40, 85]°C
-
200
mA
T = [85, 125]°C
-
100
mA
VRST
RESET pin voltage with respect to GND
-0.5 13
V
VPIN
Pin voltage with respect to GND
-0.5 VDD+0.5 V
IPIN
I/O pin sink/source current
-40
40
mA
Ic1
(1)
I/O pin injection current except RESET pin
VPIN < GND – 0.6V or 5.5V < VPIN
≤ 6.1V
4.9V < VDD ≤ 5.5V
-1
1
mA
Ic2(1)
I/O pin injection current except RESET pin
VPIN < GND – 0.6V or VPIN ≤ 5.5V
VDD ≤ 4.9V
-15
15
mA
Ictot
Sum of I/O pin injection current except RESET
pin
-45
45
mA
Tstorage
Storage temperature
-65
150
°C
Note:
1.
– If the VPIN is lower than GND – 0.6V, then a current limiting resistor is required. The negative DC injection
current limiting resistor is calculated as R = (GND – 0.6V – VPIN)/ICn.
– If the VPIN is greater than VDD+0.6V, then a current limiting resistor is required. The positive DC injection
current limiting resistor is calculated as R = (VPIN – (VDD + 0.6))/ICn.
CAUTION
VRSTMAX = 13V
Care should be taken to avoid overshoot (overvoltage) when connecting the RESET pin to a 12V source.
Exposing the pin to a voltage above the rated absolute maximum can activate the pin’s ESD protection
circuitry, which will remain activated until the voltage has been brought below approximately 10V. A 12V
driver can keep the ESD protection in an activated state (if activated by an overvoltage condition) while
driving currents through it, potentially causing permanent damage to the part.
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Electrical Characteristics
35.3
General Operating Ratings
The device must operate within the ratings listed in this section for all other electrical characteristics and typical
characteristics of the device to be valid.
Table 35-2. General Operating Conditions
Symbol
Description
VDD
Operating supply voltage
T
Operating temperature range(1)
Condition
Standard temperature range
Extended temperature
range(3)
Min.
Max.
Unit
1.8(2)
5.5
V
-40
105
°C
-40
125
Notes:
1. Refer to the device ordering codes for the device temperature range.
2. Operation is ensured down to 1.8V or BOD triggering level, VBOD. VBOD may be below the minimum Operating
Supply Voltage for some devices. Where this is the case, the device is tested down to VDD = VBOD during
production.
– During Chip Erase, the BOD is forced ON. If the supply voltage VDD is below the configured VBOD, the
Chip Erase will fail. See Chip Erase.
3. The extended temperature range is only ensured down to 2.7V.
Table 35-3. Operating Voltage and Frequency
Symbol
Description
Condition
Min.
Max.
Unit
CLK_CPU
Operating system clock frequency
VDD = [1.8, 5.5]V
T = [-40, 105]°C(1)
0
5
MHz
VDD = [2.7, 5.5]V
T = [-40, 105]°C(2)
0
10
VDD = [4.5, 5.5]V
T = [-40, 105]°C(3)
0
20
VDD = [2.7, 5.5]V
T = [-40, 125]°C(2)
0
8
VDD = [4.5, 5.5]V
T = [-40, 125]°C(3)
0
16
Notes:
1. Operation ensured down to BOD triggering level, VBOD with BODLEVEL0.
2. Operation ensured down to BOD triggering level, VBOD with BODLEVEL2.
3. Operation ensured down to BOD triggering level, VBOD with BODLEVEL7.
The maximum CPU clock frequency depends on VDD. As shown in the following figure, the maximum frequency vs.
VDD is linear between 1.8V < VDD < 2.7V and 2.7V < VDD < 4.5V.
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Electrical Characteristics
Figure 35-1. Maximum Frequency vs. VDD for [-40, 105]°C, Standard Temperature Range
20 MHz
10 MHz
Safe Operating Area
5 MHz
1.8V
2.7V
4.5V
5.5V
Figure 35-2. Maximum Frequency vs. VDD for [-40, 125]°C, Extended Temperature Range
16 MHz
8 MHz
Safe Operating Area
2.7V
35.4
4.5V
5.5V
Power Consumption
The values are measured power consumption under the following conditions, except where otherwise noted:
• VDD = 3V
• T = 25°C
• OSC20M used as the system clock source, except where otherwise specified
• System power consumption measured with peripherals disabled and without I/O drive
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Electrical Characteristics
Table 35-4. Power Consumption in Active and Idle Mode
Mode
Description
Condition
Typ. Max.
Unit
Active
Active power consumption
CLK_CPU = 20 MHz (OSC20M)
VDD = 5V
9.0
-
mA
CLK_CPU = 10 MHz (OSC20M div2)
VDD = 5V
4.8
-
mA
VDD = 3V
2.7
-
mA
VDD = 5V
2.8
-
mA
VDD = 3V
1.6
-
mA
VDD = 2V
1.0
-
mA
VDD = 5V
18
-
µA
VDD = 3V
10
-
µA
VDD = 2V
7
-
µA
CLK_CPU = 20 MHz (OSC20M)
VDD = 5V
2.8
6.3(1)
mA
CLK_CPU = 10 MHz (OSC20M div2)
VDD = 5V
1.7
3.1(1)
mA
VDD = 3V
0.9
1.9(1)
mA
VDD = 5V
1.2
2.0(1)
mA
VDD = 3V
0.6
1.2
mA
VDD = 2V
0.4
-
mA
VDD = 5V
8.0
20(1)
µA
VDD = 3V
4.0
15(1)
µA
VDD = 2V
1.7
-
µA
CLK_CPU = 5 MHz (OSC20M div4)
CLK_CPU = 32.768 kHz (OSCULP32K)
Idle
Idle power consumption
CLK_CPU = 5 MHz (OSC20M div4)
CLK_CPU = 32.768 kHz (OSCULP32K)
Note:
1. These values are based on characterization and not covered by production test limits.
Table 35-5. Power Consumption in Power-Down, Standby and Reset Mode
Mode
Description
Condition
Max.
25°C
Max.
85°C(1)
Max.
125°C
Unit
Standby
Standby power
consumption
RTC running at 1.024
kHz from external
XOSC32K (CL = 7.5
pF)
VDD = 3V 0.7
-
-
-
µA
RTC running at 1.024
kHz from internal
OSCULP32K
VDD = 3V 0.7
3.0
6.0
8.0
µA
Power
Down/
Standby
Power down/
All peripherals stopped VDD = 3V 0.1
Standby power
consumption are the
same when all
peripherals are
stopped
2.0
5.0
7.0
µA
Reset
Reset power
consumption
-
-
-
µA
© 2020 Microchip Technology Inc.
Typ.
25°C
Reset line pulled down VDD = 3V 100
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Electrical Characteristics
Note:
1. These values are based on characterization and not covered by production test limits.
35.5
Wake-Up Time
Wake-up time from sleep mode is measured from the edge of the wake-up signal to the first instruction executed.
Operating conditions:
• VDD = 3V
• T = 25°C
• OSC20M as the system clock source, unless otherwise specified
Table 35-6. Start-Up, Reset, and Wake-Up Time from OSC20M
Symbol Description
twakeup
Condition
Start-up time from any Reset release
Wake-up from Idle sleep mode
-
200
-
OSC20M @ 20 MHz
VDD = 5V
-
1
-
OSC20M @ 10 MHz
VDD = 3V
-
2
-
OSC20M @ 5 MHz
VDD = 2V
-
4
-
-
10
-
Wake-up from Standby and Power-Down sleep mode
35.6
Min. Typ. Max. Unit
µs
Peripherals Power Consumption
Use the table below to calculate the additional current consumption for the different I/O peripherals in the various
operating modes.
Operating conditions:
• VDD = 3V
• T = 25°C
• OSC20M at 1 MHz used as the system clock source, except where otherwise specified
• In Idle sleep mode, except where otherwise specified
Table 35-7. Peripherals Power Consumption
Peripheral
Conditions
Typ.(1)
Unit
BOD
Continuous
19
µA
Sampling @ 1 kHz
1
TCA
16-bit count @ 1 MHz
13
µA
TCB
16-bit count @ 1 MHz
7.5
µA
RTC
16-bit count @ 32.768 kHz @ OSCULP32K
1
µA
WDT (including OSCULP32K)
1
µA
OSC20M
125
µA
92
µA
45
µA
AC
Fast mode(2)
Low-Power
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Electrical Characteristics
...........continued
Peripheral
Conditions
Typ.(1)
Unit
ADC
50 ksps
325
µA
100 ksps
340
µA
CL = 7.5 pF
0.5
µA
0.5
µA
XOSC32K
OSCULP32K
USART
Enable @ 9600 Baud
13
µA
SPI (Host)
Enable @ 100 kHz
2
µA
TWI (Host)
Enable @ 100 kHz
24
µA
TWI (Client)
Enable @ 100 kHz
17
µA
Flash programming
Erase Operation
1.5
mA
Write Operation
3.0
Notes:
1. The current consumption of the module only. To calculate the total power consumption of the system, add this
value to the base power consumption as listed in Power Consumption.
2. The CPU in Standby sleep mode.
35.7
BOD and POR Characteristics
Table 35-8. Power Supply Characteristics
Symbol
Description
SRON
Power-on Slope
Condition
Min.
Typ.
Max.
Unit
-
-
100
V/ms
Table 35-9. Power-on Reset (POR) Characteristics
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
VPOR
POR threshold voltage on VDD falling
VDD falls/rises at 0.5 V/ms or slower
0.8
-
1.6
V
1.4
-
1.8
POR threshold voltage on VDD rising
Table 35-10. Brown-out Detection (BOD) Characteristics
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
VBOD
BOD triggering level (falling/rising)
BODLEVEL7
3.9
4.2
4.5
V
BODLEVEL2
2.4
2.6
2.9
BODLEVEL0
1.7
1.8
2.0
BOD.VLMLVL = 0x0
-
4
-
BOD.VLMLVL = 0x1
-
13
-
BOD.VLMLVL = 0x2
-
25
-
VVLM
VLM threshold relative to BOD triggering level
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Electrical Characteristics
...........continued
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
VHYS
Hysteresis
BODLEVEL7
-
80
-
mV
BODLEVEL2
-
40
-
BODLEVEL0
-
25
-
Continuous
-
7
-
µs
Sampled, 1 kHz
-
1
-
ms
Sampled, 125 Hz
-
8
-
Time from enable to ready
-
40
-
TBOD
TStart
35.8
Detection time
Start-up time
µs
External Reset Characteristics
Table 35-11. External Reset Characteristics
35.9
Symbol
Description
VHVRST
Condition
Min.
Typ.
Max.
Unit
Ensured detection for a high-voltage Reset
11.5
-
12.5
V
VRST_VIH
Input high-voltage for RESET
0.8 × VDD
-
VDD + 0.2
VRST_VIL
Input low-voltage for RESET
-0.2
-
0.2 × VDD
tRST
Minimum pulse-width on the RESET pin
-
-
2.5
µs
RRST
RESET pull-up resistor
20
-
60
kΩ
VReset = 0V
Oscillators and Clocks
Operating conditions:
• VDD = 3V, except where specified otherwise
Table 35-12. Internal Oscillator (OSC20M) Characteristics
Symbol
Description
fOSC20M Accuracy with 16 MHz and 20 MHz frequency selection
relative to the factory-stored frequency value
Accuracy with 16 MHz and 20 MHz frequency selection
fCAL
User calibration range
Condition
Min. Typ. Max. Unit
Factory calibrated
VDD = 3V(1)
T = [0, 70]°C,
VDD = [1.8, 4.5]V(3)
-2.0
-
2.0
Factory calibrated
VDD = 5V(1)
T = [0, 70]°C,
VDD = [4.5, 5.5]V(3)
-2.0
-
2.0
Factory calibrated
T = 25°C, 3.0V
-3.0
-
3.0
T = [0, 70]°C,
VDD = [1.8, 3.6]V(3)
-4.0
-
4.0
Full operation range(3) -5.0
-
5.0
OSC20M(2) = 16 MHz
14.5 -
17.5
OSC20M(2) = 20 MHz
18.5 -
21.5
%
%
MHz
%CAL
Calibration step size
-
1.5
-
%
DC
Duty cycle
-
50
-
%
TStart
Start-up time
-
8
-
µs
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Electrical Characteristics
Notes:
1. See the description of OSC20M on calibration.
2. Oscillator frequencies above speed specification must be divided so that the CPU clock always is within
specification.
3. These values are based on characterization and not covered by production test limits.
Table 35-13. 32.768 kHz Internal Oscillator (OSCULP32K) Characteristics
Symbol
Description
Condition
fOSCULP32K
Accuracy
Factory calibrated
Min.
Typ.
Max.
Unit
T = 25°C, 3.0V
-3
-
3
%
T = [0, 70]°C,
VDD = [1.8, 3.6]V(1)
-10
-
10
Full operation range(1)
-30
-
30
DC
Duty cycle
-
50
-
%
TStart
Start-up time
-
250
-
µs
Note:
1. These values are based on characterization and not covered by production test limits.
Table 35-14. 32.768 kHz External Crystal Oscillator (XOSC32K) Characteristics
Symbol
Description
Condition
Fout
Frequency
TStart
Start-up time
CL
Crystal load capacitance
CTOSC1
Parasitic capacitor load
CL = 7.5 pF
CTOSC2
ESR
Equivalent Series Resistance - Safety Factor = 3
Min.
Typ.
Max.
Unit
-
32.768
-
kHz
-
300
-
ms
7.5
-
12.5
pF
-
5.5
-
pF
-
5.5
-
pF
CL = 7.5 pF
-
-
80
kΩ
CL = 12.5 pF
-
-
40
Figure 35-3. External Clock Waveform Characteristics
V IH1
V IL1
Table 35-15. External Clock Characteristics
Symbol
Description
Condition
VDD = [1.8, 5.5]V
VDD = [2.7, 5.5]V
VDD = [4.5, 5.5]V
Min.
Max.
Min.
Max.
Min.
Max.
Unit
fCLCL
Frequency
0
5.0
0.0
10.0
0.0
20.0
MHz
tCLCL
Clock period
200
-
100
-
50
-
ns
tCHCX
High time
80
-
40
-
20
-
ns
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Electrical Characteristics
...........continued
Symbol
tCLCX
35.10
Description
Condition
Low time
VDD = [1.8, 5.5]V
VDD = [2.7, 5.5]V
VDD = [4.5, 5.5]V
Min.
Max.
Min.
Max.
Min.
Max.
80
-
40
-
20
-
Unit
ns
I/O Pin Characteristics
Table 35-16. I/O Pin Characteristics (TA = [-40, 105]°C, VDD = [1.8, 5.5]V Unless Otherwise Stated)
Symbol
Description
VIL
Min.
Typ.
Max.
Unit
Input low-voltage, except RESET pin as I/O
-0.2
-
0.3 × VDD
V
VIH
Input high-voltage, except RESET pin as I/O
0.7 × VDD
-
VDD + 0.2V
V
IIH / IIL
I/O pin input leakage current, except RESET pin as I/O
VDD = 5.5V, pin high
-
< 0.05
-
µA
VDD = 5.5V, pin low
-
< 0.05
-
VDD = 1.8V, IOL = 1.5 mA
-
-
0.36
VDD = 3.0V, IOL = 7.5 mA
-
-
0.6
VDD = 5.0V, IOL = 15 mA
-
-
1
VDD = 1.8V, IOH = 1.5 mA
1.44
-
-
VDD = 3.0V, IOH = 7.5 mA
2.4
-
-
VDD = 5.0V, IOH = 15 mA
4
-
-
Maximum combined I/O sink current per pin group(1)
-
-
100
Maximum combined I/O source current per pin group(1)
-
-
100
VIL2
Input low-voltage on RESET pin as I/O
-0.2
-
0.3 × VDD
V
VIH2
Input high-voltage on RESET pin as I/O
0.7 × VDD
-
VDD + 0.2V
V
VOL2
I/O pin drive strength on RESET pin as I/O
VDD = 1.8V, IOL = 0.1 mA
-
-
0.36
V
VDD = 3.0V, IOL = 0.25 mA
-
-
0.6
VDD = 5.0V, IOL = 0.5 mA
-
-
1
VDD = 1.8V, IOH = 0.1 mA
1.44
-
-
VDD = 3.0V, IOH = 0.25 mA
2.4
-
-
VDD = 5.0V, IOH = 0.5 mA
4
-
-
VDD = 3.0V, load = 20 pF
-
2.5
-
VDD = 5.0V, load = 20 pF
-
1.5
-
VDD = 3.0V, load = 20 pF
-
2.0
-
VDD = 5.0V, load = 20 pF
-
1.3
-
VOL
VOH
Itotal
VOH2
tRISE
tFALL
I/O pin drive strength
I/O pin drive strength
I/O pin drive strength on RESET pin as I/O
Rise time
Fall time
Condition
V
V
mA
V
ns
ns
CPIN
I/O pin capacitance except TOSC and TWI pins
-
3
-
pF
CPIN
I/O pin capacitance on TOSC pins
-
5.5
-
pF
CPIN
I/O pin capacitance on TWI pins
-
10
-
pF
RP
Pull-up resistor
20
35
50
kΩ
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Electrical Characteristics
Note:
1. Pin group x (Px[7:0]). The combined continuous sink/source current for all I/O ports should not exceed the
limits.
35.11
TCD
Operating conditions:
• CLK_TCD frequencies above maximum CLK_TCD_SYNC must be prescaled with the Synchronization
Prescaler (SYNCPRES in TCDn.CTRLA), so the synchronizer clock meets these specifications
Table 35-17. Timer/Counter D Maximum Frequency(1)
Symbol
Description
Condition
fCLK_TCD_SYNC
CLK_TCD_SYNC maximum frequencies
VDD = [1.8, 5.5]V
Max.
Unit
TA = [-40, 125]°C
8
MHz
VDD = [2.7, 5.5]V
TA = [-40, 125]°C
16
VDD = [4.5, 5.5]V
TA = [-40, 105]°C
32
TA = [-40, 125]°C
20
Note:
1. These parameters are for design guidance only and are not covered by production test limits.
35.12
USART
Figure 35-4. USART in SPI Mode - Timing Requirements in Host Mode
SS
tSCKR
tMOS
tSCKF
SCK
(CPOL = 0)
tSCKW
SCK
(CPOL = 1)
tSCKW
tMIS
MISO
(Data Input)
tMIH
tSCK
MSb
LSb
tMOH
tMOH
MOSI
(Data Output)
MSb
LSb
Table 35-18. USART in SPI Host Mode - Timing Characteristics
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
fSCK
SCK clock frequency
Host
-
-
10
MHz
tSCK
SCK period
Host
100
-
-
ns
tSCKW
SCK high/low width
Host
-
0.5 × tSCK
-
ns
tSCKR
SCK rise time
Host
-
2.7
-
ns
tSCKF
SCK fall time
Host
-
2.7
-
ns
tMIS
MISO setup to SCK
Host
-
10
-
ns
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 508
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
35.13
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
tMIH
MISO hold after SCK
Host
-
10
-
ns
tMOS
MOSI setup to SCK
Host
-
0.5 × tSCK
-
ns
tMOH
MOSI hold after SCK
Host
-
1.0
-
ns
SPI
Figure 35-5. SPI - Timing Requirements in Host Mode
SS
tSCKR
tMOS
tSCKF
SCK
(CPOL = 0)
tSCKW
SCK
(CPOL = 1)
tSCKW
tMIS
MISO
(Data Input)
tMIH
tSCK
MSb
LSb
tMOH
tMOH
MOSI
(Data Output)
MSb
LSb
Figure 35-6. SPI - Timing Requirements in Client Mode
SS
tSSCKR
tSSS
tSSCKF
tSSH
SCK
(CPOL = 0)
tSSCKW
SCK
(CPOL = 1)
tSSCKW
tSIS
MOSI
(Data Input)
tSIH
MSb
tSOSS
MISO
(Data Output)
tSSCK
LSb
tSOS
tSOSH
MSb
LSb
Table 35-19. SPI - Timing Characteristics
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
fSCK
SCK clock frequency
Host
-
-
10
MHz
tSCK
SCK period
Host
100
-
-
ns
tSCKW
SCK high/low width
Host
-
0.5 × tSCK
-
ns
tSCKR
SCK rise time
Host
-
2.7
-
ns
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 509
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
35.14
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
tSCKF
SCK fall time
Host
-
2.7
-
ns
tMIS
MISO setup to SCK
Host
-
10
-
ns
tMIH
MISO hold after SCK
Host
-
10
-
ns
tMOS
MOSI setup to SCK
Host
-
0.5 × tSCK
-
ns
tMOH
MOSI hold after SCK
Host
-
1.0
-
ns
fSSCK
Client SCK clock frequency
Client
-
-
5
MHz
tSSCK
Client SCK Period
Client
4 × tCLK_PER
-
-
ns
tSSCKW
SCK high/low width
Client
2 × tCLK_PER
-
-
ns
tSSCKR
SCK rise time
Client
-
-
1600
ns
tSSCKF
SCK fall time
Client
-
-
1600
ns
tSIS
MOSI setup to SCK
Client
3.0
-
-
ns
tSIH
MOSI hold after SCK
Client
tCLK_PER
-
-
ns
tSSS
SS setup to SCK
Client
21
-
-
ns
tSSH
SS hold after SCK
Client
20
-
-
ns
tSOS
MISO setup to SCK
Client
-
8.0
-
ns
tSOH
MISO hold after SCK
Client
-
13
-
ns
tSOSS
MISO setup after SS low
Client
-
11
-
ns
tSOSH
MISO hold after SS low
Client
-
8.0
-
ns
TWI
Figure 35-7. TWI - Timing Requirements
tHIGH
tOF
SCL
tSU;STA
tHD ;STA
tSU ;DAT
tLOW
tSP
tR
tHD ;DAT
tSU ;STO
tBUF
SDA
S
P
S
Table 35-20. TWI - Timing Characteristics
Symbol Description
Condition
fSCL
SCL clock frequency
Max. frequency requires the system 0
clock running at 10 MHz, which, in
turn, requires VDD = [2.7, 5.5]V and
T = [-40, 105]°C
VIH
Input high voltage
© 2020 Microchip Technology Inc.
Min.
0.7 × VDD
Complete Datasheet
Typ. Max.
Unit
-
1000
kHz
-
-
V
DS40002287A-page 510
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol Description
Condition
Min.
Typ. Max.
Unit
-
0.3 × VDD
V
0.4 × VDD
V
V
VIL
Input low voltage
-
VHYS
Hysteresis of Schmitt
trigger inputs
0.1 × VDD
VOL
Output low voltage
IOL
CB
tR
tOF
Low-level output
current
Capacitive load for
each bus line
Rise time for both
SDA and SCL
Output fall time from
VIHmin to VILmax
Iload = 20 mA, Fast mode+
-
-
0.2 × VDD
Iload = 3 mA, Normal mode, VDD >
2V
-
-
0.4
Iload = 3 mA, Normal mode, VDD ≤
2V
-
-
0.2 × VDD
fSCL ≤ 400 kHz, VOL = 0.4V
3
-
-
fSCL ≤ 1 MHz, VOL = 0.4V
20
-
-
fSCL ≤ 100 kHz
-
-
400
fSCL ≤ 400 kHz
-
-
400
fSCL ≤ 1 MHz
-
-
550
fSCL ≤ 100 kHz
-
-
1000
fSCL ≤ 400 kHz
20
-
300
fSCL ≤ 1 MHz
-
-
120
10 pF < Capacitance fSCL ≤ 400
of bus line < 400 pF kHz
20 × (VDD/
5.5V)
-
250
fSCL ≤ 1 MHz 20 × (VDD/
5.5V)
-
120
mA
pF
ns
ns
tSP
Spikes suppressed
by Input filter
0
-
50
ns
IL
Input current for each 0.1×VDD < VI < 0.9×VDD
I/O pin
-
-
1
µA
CI
Capacitance for each
I/O pin
-
-
10
pF
RP
Value of pull-up
resistor
1000 ns/
(0.8473 × CB)
Ω
fSCL ≤ 100 kHz
(VDD VOL(max)) /IO
L
tHD;STA
Hold time (repeated)
Start condition
© 2020 Microchip Technology Inc.
fSCL ≤ 400 kHz
-
-
300 ns/
(0.8473 × CB)
fSCL ≤ 1 MHz
-
-
120 ns/
(0.8473 × CB)
fSCL ≤ 100 kHz
4.0
-
-
fSCL ≤ 400 kHz
0.6
-
-
fSCL ≤ 1 MHz
0.26
-
-
Start
-
2.1
-
TSCL
Repeated start
-
3.1
-
TSCL
Complete Datasheet
µs
DS40002287A-page 511
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol Description
Condition
Min.
Typ. Max.
Unit
tLOW
fSCL ≤ 100 kHz
4.7
-
-
µs
fSCL ≤ 400 kHz
1.3
-
-
fSCL ≤ 1 MHz
0.5
-
-
fSCL ≤ 100 kHz
4.0
-
-
fSCL ≤ 400 kHz
0.6
-
-
fSCL ≤ 1 MHz
0.26
-
-
fSCL ≤ 100 kHz
4.7
-
-
fSCL ≤ 400 kHz
0.6
-
-
fSCL ≤ 1 MHz
0.26
-
-
-
-
3
-
TSCL
fSCL ≤ 100 kHz
0
-
3.45
µs
fSCL ≤ 400 kHz
0
-
0.9
fSCL ≤ 1 MHz
0
-
0.45
fSCL ≤ 100 kHz
250
-
-
fSCL ≤ 400 kHz
100
-
-
fSCL ≤ 1 MHz
50
-
-
fSCL ≤ 100 kHz
4
-
-
fSCL ≤ 400 kHz
0.6
-
-
fSCL ≤ 1 MHz
0.26
-
-
-
-
2
-
TSCL
fSCL ≤ 100 kHz
4.7
-
-
µs
fSCL ≤ 400 kHz
1.3
-
-
fSCL ≤ 1 MHz
0.5
-
-
-
-
2
-
tHIGH
tSU;STA
tHD;DAT
tSU;DAT
tSU;STO
tBUF
Low period of SCL
Clock
High period of SCL
Clock
Setup time for a
repeated Start
condition
Data hold time
Data setup time
Setup time for Stop
condition
Bus free time
between a Stop and
Start condition
© 2020 Microchip Technology Inc.
Complete Datasheet
µs
µs
ns
µs
TSCL
DS40002287A-page 512
ATtiny212/214/412/414/416
Electrical Characteristics
Table 35-21. SDA Hold Time(1,2)
Symbol
tHD;DAT
Description
Condition
Data hold time
Host(3)
fCLK_PER = 5 MHz
fCLK_PER = 10 MHz
fCLK_PER = 20 MHz
tHD;DAT
Data hold time
Client(4)
All frequencies
Min.
Typ.
Max.
Unit
SDAHOLD = 0x00
-
800
-
ns
SDAHOLD = 0x01
830
850
950
SDAHOLD = 0x02
830
850
950
SDAHOLD = 0x03
830
850
1270
SDAHOLD = 0x00
-
400
-
SDAHOLD = 0x01
430
450
550
SDAHOLD = 0x02
430
450
580
SDAHOLD = 0x03
430
550
1270
SDAHOLD = 0x00
-
200
220
SDAHOLD = 0x01
230
250
350
SDAHOLD = 0x02
260
450
580
SDAHOLD = 0x03
380
600
1270
SDAHOLD = 0x00
90
150
220
SDAHOLD = 0x01
130
200
350
SDAHOLD = 0x02
260
400
580
SDAHOLD = 0x03
390
550
1270
ns
Notes:
1. These parameters are for design guidance only and are not covered by production test limits.
2. SDAHOLD is the data hold time after the SCL signal is detected as low. The actual hold time is, therefore,
higher than the configured hold time.
3. For Host mode, the data hold time is whatever is largest of the following:
– 4 × tCLK_PER + 50 ns (typical)
– SDAHOLD configuration + SCL filter delay
4. For Client mode, the hold time is given by:
– SDAHOLD configuration + SCL filter delay
35.15
VREF
Table 35-22. Internal Voltage Reference Characteristics
Symbol
Description
Min.
Typ.
Max.
Unit
TStart
Start-up time
-
25
-
µs
VDDINT055V
Power supply voltage range for INT055V
1.8
-
5.5
V
VDDINT11V
Power supply voltage range for INT11V
1.8
-
5.5
VDDINT15V
Power supply voltage range for INT15V
1.9
-
5.5
VDDINT25V
Power supply voltage range for INT25V
2.9
-
5.5
VDDINT43V
Power supply voltage range for INT43V
4.75
-
5.5
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 513
ATtiny212/214/412/414/416
Electrical Characteristics
Table 35-23. ADC Internal Voltage Reference Characteristics(1)
Symbol(2)
Description
Condition
Min.
INT11V
Internal reference voltage
VDD = [1.8V, 3.6V]
T = [0, 105]°C
INT055V
INT15V
INT25V
Internal reference voltage
INT055V
INT11V
INT15V
INT25V
INT43V
Internal reference voltage
Typ.
Max.
Unit
-2.0
2.0
%
VDD = [1.8V, 3.6V]
T = [0, 105]°C
-3.0
3.0
VDD = [1.8V, 5.5V]
T = [-40, 125]°C
-5.0
5.0
Notes:
1. These values are based on characterization and not covered by production test limits.
2. The symbols INTxxV refer to the respective values of the ADC0REFSEL and DAC0REFSEL bit fields in the
VREF.CTRLA register.
Table 35-24. DAC and AC Internal Voltage Reference Characteristics(1)
Symbol(2)
Description
Condition
Min.
INT055V
INT11V
INT15V
INT25V
Internal reference voltage
VDD = [1.8V, 3.6V]
T = [0, 105]°C
INT055V
INT11V
INT15V
INT25V
INT43V
Internal reference voltage
VDD = [1.8V, 5.5V]
T = [-40, 125]°C
Typ.
Max.
Unit
-3.0
3.0
%
-5.0
5.0
Notes:
1. These values are based on characterization and not covered by production test limits.
2. The symbols INTxxV refer to the respective values of the ADC0REFSEL and DAC0REFSEL bit fields in the
VREF.CTRLA register.
35.16
ADC
Operating conditions:
• VDD = 1.8V to 5.5V
• Temperature = -40°C to 125°C
• DUTYCYC = 25%
• CLKADC = 13 × fADC
• SAMPCAP is 10 pF for 0.55V reference, while it is set to 5 pF for VREF ≥ 1.1V
• Applies for all allowed combinations of VREF selections and Sample Rates unless otherwise stated
Table 35-25. Power Supply, Reference, and Input Range
Symbol
Description
VDD
Supply voltage
© 2020 Microchip Technology Inc.
Conditions
Complete Datasheet
Min.
Typ.
Max.
Unit
1.8
-
5.5
V
DS40002287A-page 514
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol
Description
Conditions
Min.
Typ.
Max.
Unit
VREF
Reference voltage
REFSEL = Internal reference
0.55
-
VDD - 0.4
V
REFSEL = VDD
1.8
-
5.5
SAMPCAP = 5 pF
-
5
-
SAMPCAP = 10 pF
-
10
-
CIN
Input capacitance
pF
RIN
Input resistance
-
14
-
kΩ
VIN
Input voltage range
0
-
VREF
V
IBAND
Input bandwidth
-
-
57.5
kHz
1.1V ≤ VREF
Table 35-26. Clock and Timing Characteristics
Symbol
Description
Conditions
Min.
Typ.
Max.
Unit
fADC
Sample rate
1.1V ≤ VREF
15
-
115
ksps
1.1V ≤ VREF (8-bit resolution)
15
-
150
VREF = 0.55V (10 bits)
7.5
-
20
VREF = 0.55V (10 bits)
100
-
260
1.1V ≤ VREF (10 bits)
200
-
1500
1.1V ≤ VREF (8-bit resolution)
200
-
2000(1)
2
2
33
CLKADC cycles
CLKADC
Clock frequency
kHz
Ts
Sampling time
TCONV
Conversion time (latency)
Sampling time = 2 CLKADC
8.7
-
50
µs
TSTART
Start-up time
Internal VREF
-
22
-
µs
Note:
1. 50% duty cycle is required for clock frequencies above 1500 kHz.
Table 35-27. Accuracy Characteristics(2)
Symbol
Description
RES
Resolution
INL
Integral
nonlinearity
Conditions
Min.
Typ.
Max.
Unit
-
10
-
bit
fADC = 7.7 ksps
-
1.0
-
LSb
REFSEL =
INTERNAL or VDD
fADC = 15 ksps
-
1.0
-
REFSEL =
INTERNAL or VDD
fADC = 77 ksps
-
1.0
-
fADC = 115 ksps
-
1.2
-
REFSEL =
INTERNAL
VREF = 0.55V
1.1V ≤ VREF
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 515
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol
Description
Conditions
Min.
Typ.
Max.
Unit
DNL(1)
Differential
nonlinearity
REFSEL =
INTERNAL
fADC = 7.7 ksps
-
0.6
-
LSb
REFSEL =
INTERNAL or VDD
fADC = 15 ksps
-
0.4
-
REFSEL =
INTERNAL or VDD
fADC = 77 ksps
-
0.4
-
fADC = 115 ksps
-
0.6
-
fADC = 115 ksps
-
0.6
-
T = [0, 105]°C
-
3
-
-
3
-
REFSEL = VDD
-
2
-
REFSEL =
INTERNAL
-
3
-
-
5
-
-
5
-
REFSEL = VDD
-
2
-
REFSEL =
INTERNAL
-
5
-
-
-0.5
-
LSb
VREF = 0.55V
1.1V ≤ VREF
REFSEL =
INTERNAL
1.1V ≤ VREF
REFSEL = VDD
1.1V ≤ VREF
EABS
Absolute
accuracy
REFSEL =
INTERNAL
VREF = 1.1V
EGAIN
Gain error
REFSEL =
INTERNAL
VREF = 1.1V
EOFF
LSb
VDD = [1.8V, 3.6V]
VDD = [1.8V, 3.6V]
T = [0, 105]°C
LSb
VDD = [1.8V, 3.6V]
VDD = [1.8V, 3.6V]
Offset error
Notes:
1. A DNL error of ≤ 1 LSb ensures a monotonic transfer function with no missing codes.
2. These values are based on characterization and not covered by production test limits.
35.17
TEMPSENSE
Operating conditions:
• VDD = 3V
• TA = 25°C (unless otherwise stated)
Table 35-28. Temperature Sensor, Accuracy Characteristics
Symbol
Description
VDD
Supply voltage
TACC
Sensor
accuracy(1,2)
© 2020 Microchip Technology Inc.
Condition
TA = 25°C
Complete Datasheet
Min.
Typ.
Max.
Unit
1.8
-
5.5
V
-
±3
-
°C
DS40002287A-page 516
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol
Description
Condition
Min.
Typ.
Max.
Unit
TRES
Conversion resolution
10 bits
-
0.55
-
°C
tCONV
Conversion time
1 MHz ADC clock
-
13
-
µs
Notes:
1. These values are based on characterization and not covered by production test limits.
2. Characteristics over temperature can be found in the Typical Characteristics section.
35.18
DAC
VDD = 3V, unless stated otherwise.
Accuracy characteristics calculated based on 5% to 95% range of the DAC.
Table 35-29. Power Supply, Reference, and Input Range
Symbol
Description
Min.
Typ.
Max.
Unit
VDD
Supply voltage(1)
1.8
3
5.5
V
RLoad
Resistive external load
5
-
-
kΩ
CLoad
Capacitive external load
-
-
30
pF
VOUT
Output voltage range
0.2
-
VDD-0.2
V
IOUT
Output sink/source
-
1
-
mA
Note: 1. The supply voltage must meet the VDD specification for the VREF level used as DAC reference.
Table 35-30. Clock and Timing Characteristics
Symbol
Description
Conditions
Min.
Typ.
Max.
Unit
fDAC
Maximum conversion rate
0.55V ≤ VREF ≤ 2.5V
-
350
-
ksps
VREF = 4.3V
-
270
-
ksps
Table 35-31. Accuracy Characteristics(3)
Symbol
Description
RES
Resolution
INL
Integral nonlinearity
0.55V ≤ VREF ≤ 4.3V
-1.2
DNL
Differential nonlinearity
0.55V ≤ VREF ≤ 4.3V
EOFF(1)
Offset error
EGAIN(2)
Gain error
Conditions
Min.
Typ.
Max.
Unit
8
bits
0.3
1.2
LSb
-1
0.25
1
LSb
0.55V ≤ VREF ≤ 1.5V
-25
-3
20
mV
VREF = 2.5V
-30
-6
10
VREF = 4.3V
-40
-10
0
VREF = 1.1V, VDD = 3.0V, T = 25°C
-
±1
-
0.55V ≤ VREF ≤ 4.3V
-10
-1
10
-
LSb
Notes:
1. Offset including the DAC output buffer offset, this measured at DAC output pin.
2. VREF accuracy is included in the Gain accuracy specification.
3. These values are based on characterization and not covered by production test limits.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 517
ATtiny212/214/412/414/416
Electrical Characteristics
35.19
AC
Table 35-32. Analog Comparator Characteristics, Low-Power Mode Disabled
Symbol Description
Condition
Min. Typ. Max. Unit
VIN
Input voltage
-0.2
-
VDD
V
CIN
Input pin capacitance PA6
-
9
-
pF
PA7, PB5, PB4
-
5
-
0.7V < VIN < (VDD - 0.7V)
-20
±5
20
VIN = [-0.2V, VDD]
-40
±20
40
VOFF
Input offset voltage
mV
IL
Input leakage current
-
5
-
nA
TSTART
Start-up time
-
1.3
-
µs
VHYS
Hysteresis
HYSMODE = 0x0
0
0
10
mV
HYSMODE = 0x1
0
10
30
HYSMODE = 0x2
10
30
90
HYSMODE = 0x3
20
55
150
50
-
ns
tPD
Propagation delay
25 mV Overdrive, VDD ≥ 2.7V, Low-Power mode disabled -
Table 35-33. Analog Comparator Characteristics, Low-Power Mode Enabled
Symbol
Description
VIN
Input voltage
CIN
Input pin capacitance
VOFF
Min.
Typ.
Max.
Unit
0
-
VDD
V
PA6
-
9
-
pF
PA7, PB5, PB4
-
5
-
0.7V < VIN < (VDD - 0.7V)
-30
±10
30
VIN = [0V, VDD]
-50
±30
50
mV
IL
Input leakage current
-
5
-
nA
TSTART
Start-up time
-
1.3
-
µs
VHYS
Hysteresis
HYSMODE = 0x0
0
0
10
mV
HYSMODE = 0x1
0
10
30
HYSMODE = 0x2
5
30
90
HYSMODE = 0x3
12
55
190
25 mV Overdrive, VDD ≥ 2.7V
-
150
-
tPD
35.20
Input offset voltage
Condition
Propagation delay
ns
UPDI Timing
UPDI Enable Sequence with UPDI PAD Enabled by Fuse(1)
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 518
ATtiny212/214/412/414/416
Electrical Characteristics
1
Fuse read in. Pull-up enabled. Ready to receive init.
2
Drive low from debugger to request UPDI clock.
3
UPDI clock ready; Communication channel ready.
RESET
1
2
Hi-Z
St
D0
D1
D2
D3
Handshake / BREAK
TRES
UPDI.rxd
D4
D5
D6
D7
Sp
SYNC (0x55)
(Auto-baud)
(Ignore)
UPDI.txd
3
Hi-Z
Hi-Z
UPDI.txd = 0
TUPDI
debugger.
UPDI.txd
Hi-Z
Hi-Z
Debugger.txd = 0
TDeb0
Debugger.txd = z
TDebZ
Table 35-34. UPDI Timing Characteristics(1)
Symbol
Description
Min.
Max.
Unit
TRES
Duration of Handshake/BREAK on RESET
10
200
µs
TUPDI
Duration of UPDI.txd = 0
10
200
µs
TDeb0
Duration of Debugger.txd = 0
0.2
1
µs
TDebZ
Duration of Debugger.txd = z
200
14000
µs
Note:
1. These parameters are for design guidance only and are not covered by production test limits.
Table 35-35. UPDI Max. Bit Rates vs. VDD(1)
Symbol
Description
Condition
Max
Unit
fUPDI
UPDI baud rate
VDD = [1.8, 5.5]V
TA = [0, 50]°C
225
kbps
VDD = [2.2, 5.5]V
TA = [0, 50]°C
450
kbps
VDD = [2.7, 5.5]V
TA = [0, 50]°C
0.9
Mbps
Note:
1. These parameters are for design guidance only and are not covered by production test limits.
35.21
Programming Time
See the following table for typical programming times for Flash and EEPROM.
Table 35-36. Programming Times
Symbol
Typical Programming Time
Page Buffer Clear (PBC)
Seven CLK_CPU cycles
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 519
ATtiny212/214/412/414/416
Electrical Characteristics
...........continued
Symbol
Typical Programming Time
Page Write (WP)
2 ms
Page Erase (ER)
2 ms
Page Erase-Write (ERWP)
4 ms
EEPROM Erase (EEER)
4 ms
Chip Erase with UPDI
50 ms (1)
30 ms (2)
Notes:
1. This is the typical chip erase time for devices with 4 KB of Flash.
2. This is the typical chip erase time for devices with 2 KB of Flash.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 520
ATtiny212/214/412/414/416
Typical Characteristics
36.
Typical Characteristics
36.1
Power Consumption
36.1.1
Supply Currents in Active Mode
Figure 36-1. Active Supply Current vs. Frequency (1-20 MHz) at T = 25°C (EXTCLK)
VDD [V]
12.0
1.8
2.2
2.7
3
3.6
4.2
5
5.5
11.0
10.0
9.0
IDD [mA]
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0
2
4
6
8
10
12
Frequency [MHz]
14
16
18
20
Figure 36-2. Active Supply Current vs. Frequency [0.1, 1.0] MHz at T = 25°C (EXTCLK)
VDD [V]
600
1.8
2.2
2.7
3
3.6
4.2
5
5.5
550
500
450
IDD [μA]
400
350
300
250
200
150
100
50
0
0.0
0.1
0.2
© 2020 Microchip Technology Inc.
0.3
0.4
0.5
0.6
Frequency [MHz]
0.7
0.8
Complete Datasheet
0.9
1.0
DS40002287A-page 521
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-3. Active Supply Current vs. Temperature (f = 20 MHz OSC20M)
VDD [V]
12.0
4.5
5
5.5
11.0
10.0
9.0
IDD [mA]
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
-40
-20
0
20
40
Temperature [°C]
60
80
100
120
Figure 36-4. Active Supply Current vs. VDD (f = [1.25, 20] MHz OSC20M) at T = 25°C
Frequency [MHz]
12.0
1.25
2.5
5
10
20
11.0
10.0
9.0
IDD [mA]
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1.5
2.0
2.5
© 2020 Microchip Technology Inc.
3.0
3.5
VDD [V]
4.0
4.5
Complete Datasheet
5.0
5.5
DS40002287A-page 522
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-5. Active Supply Current vs. VDD (f = 32.768 kHz OSCULP32K)
Temperature [°C]
32
-40
-20
0
25
70
85
105
125
28
24
IDD [μA]
20
16
12
8
4
0
2.0
2.5
3.0
3.5
4.0
VDD [V]
4.5
5.0
5.5
Supply Currents in Idle Mode
Figure 36-6. Idle Supply Current vs. Frequency (1-20 MHz) at T = 25°C (EXTCLK)
VDD [V]
5.0
1.8
2.2
2.7
3
3.6
4.2
5
5.5
4.5
4.0
3.5
3.0
IDD [mA]
36.1.2
1.5
2.5
2.0
1.5
1.0
0.5
0.0
0
2
4
© 2020 Microchip Technology Inc.
6
8
10
12
Frequency [MHz]
14
16
Complete Datasheet
18
20
DS40002287A-page 523
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-7. Idle Supply Current vs. Low Frequency (0.1-1.0 MHz) at T = 25°C (EXTCLK)
VDD [V]
250
1.8
2.2
2.7
3
3.6
4.2
5
5.5
225
200
175
IDD [μA]
150
125
100
75
50
25
0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Frequency [MHz]
0.7
0.8
0.9
1.0
Figure 36-8. Idle Supply Current vs. Temperature (f = 20 MHz OSC20M)
VDD [V]
5.0
4.5
5
5.5
4.5
4.0
3.5
IDD [mA]
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-40
-20
0
© 2020 Microchip Technology Inc.
20
40
Temperature [°C]
60
80
Complete Datasheet
100
120
DS40002287A-page 524
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-9. Idle Supply Current vs. VDD (f = 32.768 kHz OSCULP32K)
Temperature [°C]
20
-40
-20
0
25
70
85
105
125
18
16
14
IDD [μA]
12
10
8
6
4
2
0
2.0
2.5
3.0
3.5
VDD [V]
4.0
4.5
5.0
5.5
Supply Currents in Standby Mode
Figure 36-10. Standby Mode Supply Current vs. VDD (RTC Running with External 32.768 kHz Osc.)
Temperature [°C]
10.0
-40
-20
0
25
70
85
105
125
9.0
8.0
7.0
6.0
IDD [μA]
36.1.3
1.5
5.0
4.0
3.0
2.0
1.0
0.0
1.5
2.0
2.5
© 2020 Microchip Technology Inc.
3.0
3.5
VDD [V]
4.0
4.5
Complete Datasheet
5.0
5.5
DS40002287A-page 525
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-11. Standby Mode Supply Current vs. VDD (RTC Running with Internal OSCULP32K)
Temperature [°C]
10.0
-40
-20
0
25
70
85
105
125
9.0
8.0
7.0
IDD [μA]
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1.5
2.0
2.5
3.0
3.5
VDD [V]
4.0
4.5
5.0
5.5
Figure 36-12. Standby Mode Supply Current vs. VDD (Sampled BOD Running at 125 Hz)
Temperature [°C]
10.0
-40
-20
0
25
70
85
105
125
9.0
8.0
7.0
IDD [μA]
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1.5
2.0
2.5
© 2020 Microchip Technology Inc.
3.0
3.5
VDD [V]
4.0
4.5
Complete Datasheet
5.0
5.5
DS40002287A-page 526
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-13. Standby Mode Supply Current vs. VDD (Sampled BOD Running at 1 kHz)
Temperature [°C]
10.0
-40
-20
0
25
70
85
105
125
9.0
8.0
7.0
IDD [μA]
6.0
5.0
4.0
3.0
2.0
1.0
0.0
2.0
2.5
3.0
3.5
4.0
VDD [V]
4.5
5.0
5.5
Supply Currents in Power-Down Mode
Figure 36-14. Power-Down Mode Supply Current vs. Temperature (All Functions Disabled)
VDD [V]
5.0
1.8
2.2
2.7
3
3.6
4.2
5
5.5
4.5
4.0
3.5
3.0
IDD [μA]
36.1.4
1.5
2.5
2.0
1.5
1.0
0.5
0.0
-40
-20
0
© 2020 Microchip Technology Inc.
20
40
Temperature [°C]
60
80
Complete Datasheet
100
120
DS40002287A-page 527
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-15. Power-Down Mode Supply Current vs. VDD (All Functions Disabled)
Temperature [°C]
5.0
-40
-20
0
25
70
85
105
125
4.5
4.0
3.5
IDD [μA]
3.0
2.5
2.0
1.5
1.0
0.5
0.0
1.5
2.0
2.5
36.2
GPIO
36.2.1
GPIO Input Characteristics
3.0
3.5
VDD [V]
4.0
4.5
5.0
5.5
Figure 36-16. I/O Pin Input Hysteresis vs. VDD
Temperature [°C]
2.0
-40
0
25
70
85
105
125
1.8
1.6
Threshold [V]
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 528
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-17. I/O Pin Input Threshold Voltage vs. VDD (T = 25°C)
Treshold
75
VIH
VIL
70
65
Threshold [%]
60
55
50
45
40
35
30
25
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-18. I/O Pin Input Threshold Voltage vs. VDD (VIH)
Temperature [°C]
75
-40
0
25
70
85
105
125
70
65
Threshold [%]
60
55
50
45
40
35
30
25
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 529
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-19. I/O Pin Input Threshold Voltage vs. VDD (VIL)
Temperature [°C]
75
-40
0
25
70
85
105
125
70
65
Threshold [%]
60
55
50
45
40
35
30
25
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
GPIO Output Characteristics
Figure 36-20. I/O Pin Output Voltage vs. Sink Current (VDD = 1.8V)
Temperature [°C]
0.50
-40
-20
0
25
70
85
105
125
0.45
0.40
0.35
0.30
VOutput [V]
36.2.2
0.25
0.20
0.15
0.10
0.05
0.00
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Sink current [mA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 530
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-21. I/O Pin Output Voltage vs. Sink Current (VDD = 3.0V)
Temperature [°C]
0.50
-40
-20
0
25
70
85
105
125
0.45
0.40
VOutput [V]
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
1
2
3
4
5
6
7
8
9
10
Sink current [mA]
Figure 36-22. I/O Pin Output Voltage vs. Sink Current (VDD = 5.0V)
Temperature [°C]
1.0
-40
-20
0
25
70
85
105
125
0.9
0.8
0.7
VOutput [V]
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Sink current [mA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 531
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-23. I/O Pin Output Voltage vs. Sink Current (T = 25°C)
VDD [V]
1.0
1.8
2
2.2
3
4
5
0.9
0.8
0.7
VOutput [V]
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
2
4
6
8
10
12
14
16
18
20
Sink current [mA]
Figure 36-24. I/O Pin Output Voltage vs. Source Current (VDD = 1.8V)
Temperature [°C]
1.80
-40
-20
0
25
70
85
105
125
1.75
1.70
1.65
VOutput [V]
1.60
1.55
1.50
1.45
1.40
1.35
1.30
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Source current [mA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 532
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-25. I/O Pin Output Voltage vs. Source Current (VDD = 3.0V)
Temperature [°C]
3.0
-40
-20
0
25
70
85
105
125
2.9
2.8
2.7
VOutput [V]
2.6
2.5
2.4
2.3
2.2
2.1
2.0
0
1
2
3
4
5
6
7
8
9
10
Source current [mA]
Figure 36-26. I/O Pin Output Voltage vs. Source Current (VDD = 5.0V)
Temperature [°C]
5.0
-40
-20
0
25
70
85
105
125
4.9
4.8
4.7
VOutput [V]
4.6
4.5
4.4
4.3
4.2
4.1
4.0
0
2
4
6
8
10
12
14
16
18
20
Source current [mA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 533
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-27. I/O Pin Output Voltage vs. Source Current (T = 25°C)
VDD [V]
5.0
1.8
2
2.2
3
4
5
4.5
4.0
VOutput [V]
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
2
4
6
8
10
12
14
16
18
20
Source current [mA]
36.2.3
GPIO Pull-Up Characteristics
Figure 36-28. I/O Pin Pull-Up Resistor Current vs. Input Voltage (VDD = 1.8V)
Temperature [°C]
2.0
-40
-20
0
25
70
85
105
125
1.8
1.5
1.3
1.0
0.8
0.5
0.3
0.0
0
5
10
15
20
25
30
35
40
45
50
Pull-up resistor current [µA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 534
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-29. I/O Pin Pull-Up Resistor Current vs. Input Voltage (VDD = 3.0V)
Temperature [°C]
3.0
-40
-20
0
25
70
85
105
125
2.8
2.5
2.3
2.0
1.8
1.5
1.3
1.0
0
5
10
15
20
25
30
35
40
45
50
Pull-up resistor current [µA]
Figure 36-30. I/O Pin Pull-Up Resistor Current vs. Input Voltage (VDD = 5.0V)
Temperature [°C]
5.0
-40
-20
0
25
70
85
105
125
4.8
4.5
4.3
4.0
3.8
3.5
3.3
3.0
0
5
10
15
20
25
30
35
40
45
50
Pull-up resistor current [µA]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 535
ATtiny212/214/412/414/416
Typical Characteristics
VREF Characteristics
Figure 36-31. Internal 0.55V Reference vs. Temperature
VDD [V]
1.0
2
3
5
0.8
0.6
VREF error [%]
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
Figure 36-32. Internal 1.1V Reference vs. Temperature
VDD [V]
1.0
2
3
5
0.8
0.6
0.4
VREF error [%]
36.3
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 536
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-33. Internal 2.5V Reference vs. Temperature
VDD [V]
1.0
3
5
0.8
0.6
VREF error [%]
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
Figure 36-34. Internal 4.3V Reference vs. Temperature
VDD [V]
1.0
5
0.8
0.6
VREF error [%]
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 537
ATtiny212/214/412/414/416
Typical Characteristics
BOD Current vs. VDD
Figure 36-35. BOD Current vs. VDD (Continuous Mode Enabled)
Temperature [°C]
50
-40
0
25
70
85
105
125
45
40
35
30
IDD [µA]
36.4.1
BOD Characteristics
25
20
15
10
5
0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-36. BOD Current vs. VDD (Sampled BOD at 125 Hz)
Temperature [°C]
5.0
-40
0
25
70
85
105
125
4.5
4.0
3.5
3.0
IDD [µA]
36.4
2.5
2.0
1.5
1.0
0.5
0.0
1.5
2.0
2.5
© 2020 Microchip Technology Inc.
3.0
3.5
VDD [V]
4.0
4.5
Complete Datasheet
5.0
5.5
DS40002287A-page 538
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-37. BOD Current vs. VDD (Sampled BOD at 1 kHz)
Temperature [°C]
5.0
-40
0
25
70
85
105
125
4.5
4.0
IDD [µA]
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
BOD Threshold vs. Temperature
Figure 36-38. BOD Threshold vs. Temperature (Level 1.8V)
1.90
Falling VDD
Rising VDD
1.88
1.86
1.84
BOD level [V]
36.4.2
1.82
1.80
1.78
1.76
1.74
1.72
1.70
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 539
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-39. BOD Threshold vs. Temperature (Level 2.6V)
Falling VDD
Rising VDD
2.74
2.72
2.70
BOD level [V]
2.68
2.66
2.64
2.62
2.60
2.58
2.56
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
Figure 36-40. BOD Threshold vs. Temperature (Level 4.3V)
Falling VDD
Rising VDD
4.34
4.32
4.30
BOD level [V]
4.28
4.26
4.24
4.22
4.20
4.18
4.16
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 540
ATtiny212/214/412/414/416
Typical Characteristics
ADC Characteristics
Figure 36-41. Absolute Accuracy vs. VDD (fADC = 115 ksps) at T = 25°C, REFSEL = Internal Reference
VREF [V]
10.0
1.1
1.5
2.5
4.3
VDD
9.0
Absolute accuracy [LSb]
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-42. Absolute Accuracy vs. VREF (VDD = 5.0V, fADC = 115 ksps), REFSEL = Internal Reference
Temperature [°C]
10.0
-40
25
85
105
9.0
8.0
Absolute accuracy [LSb]
36.5
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1.1
1.5
2.5
4.3
VDD
VREF [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 541
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-43. DNL Error vs. VDD (fADC = 115 ksps) at T = 25°C, REFSEL = Internal Reference
VREF [V]
1.1
1.5
2.5
4.3
VDD
2.0
1.8
1.6
DNL [LSb]
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.5
2.0
2.5
3.0
3.5
VDD [V]
4.0
4.5
5.0
5.5
Figure 36-44. DNL vs. VREF (VDD = 5.0V, fADC = 115 ksps), REFSEL = Internal Reference
Temperature [°C]
2.0
-40
25
85
105
1.8
1.6
DNL [LSb]
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.1
© 2020 Microchip Technology Inc.
1.5
2.5
VREF [V]
4.3
Complete Datasheet
VDD
DS40002287A-page 542
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-45. Gain Error vs. VDD (fADC = 115 ksps) at T = 25°C, REFSEL = Internal Reference
VREF [V]
8.0
1.1
1.5
2.5
4.3
VDD
7.0
6.0
Gain [LSb]
5.0
4.0
3.0
2.0
1.0
0.0
-1.0
-2.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-46. Gain Error vs. VREF (VDD = 5.0V, fADC = 115 ksps), REFSEL = Internal Reference
Temperature [°C]
8.0
-40
25
85
105
7.0
6.0
Gain [LSb]
5.0
4.0
3.0
2.0
1.0
0.0
1.1
© 2020 Microchip Technology Inc.
1.5
2.5
VREF [V]
4.3
Complete Datasheet
VDD
DS40002287A-page 543
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-47. INL vs. VDD (fADC = 115 ksps) at T = 25°C, REFSEL = Internal Reference
VREF [V]
1.1
1.5
2.5
4.3
VDD
2.0
1.8
1.6
1.4
INL [LSb]
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-48. INL vs. VREF (VDD = 5.0V, fADC = 115 ksps), REFSEL = Internal Reference
Temperature [°C]
2.0
-40
25
85
105
1.8
1.6
INL [LSb]
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.1
© 2020 Microchip Technology Inc.
1.5
VREF [V]
2.5
4.3
Complete Datasheet
VDD
DS40002287A-page 544
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-49. Offset Error vs. VDD (fADC = 115 ksps) at T = 25°C, REFSEL = Internal Reference
VREF [V]
2.0
1.1
1.5
2.5
4.3
VDD
1.6
1.2
Offset [LSb]
0.8
0.4
0.0
-0.4
-0.8
-1.2
-1.6
-2.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
Figure 36-50. Offset Error vs. VREF (VDD = 5.0V, fADC = 115 ksps), REFSEL = Internal Reference
Temperature [°C]
2.0
-40
25
85
105
1.6
1.2
Offset [LSb]
0.8
0.4
0.0
-0.4
-0.8
-1.2
-1.6
-2.0
1.1
1.5
2.5
4.3
VDD
VREF [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 545
ATtiny212/214/412/414/416
Typical Characteristics
36.6
TEMPSENSE Characteristics
Figure 36-51. Temperature Sensor Error vs. Temperature ±3σ
Legend
14
+3σ
12
-3σ
Mean
10
Temperature sensor error [°C]
8
6
4
2
0
-2
-4
-6
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
AC Characteristics
Figure 36-52. Hysteresis vs. VCM - 10 mV (VDD = 5V)
Temperature [°C]
20
-40
-20
0
25
55
85
105
125
18
16
14
Hysteresis [mV]
36.7
12
10
8
6
4
2
0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 546
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-53. Hysteresis vs. VCM - 10 mV to 50 mV (VDD = 5V, T = 25°C)
HYSMODE [mV]
80
10
25
50
72
64
Hysteresis [mV]
56
48
40
32
24
16
8
0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
Figure 36-54. Offset vs. VCM - 10 mV (VDD = 5V)
Temperature [°C]
10.0
-40
-20
0
25
55
85
105
125
9.0
8.0
Offset [mV]
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 547
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-55. Offset vs. VCM - 10 mV to 50 mV (VDD = 5V, T = 25°C)
HYSMODE [mV]
10
10
25
50
9
8
Offset [mV]
7
6
5
4
3
2
1
0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
Figure 36-56. Propagation Delay vs. VCM LPMODE Enabled, Falling Positive Input, VOD = 25 mV (T = 25°C)
VDD [V]
500
3
5
Propagation delay [ns]
400
300
200
100
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 548
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-57. Propagation Delay vs. VCM LPMODE Enabled, Rising Positive Input, VOD = 30 mV (T = 25°C)
VDD [V]
500
3
5
Propagation delay [ns]
400
300
200
100
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
Figure 36-58. Propagation Delay vs. VCM LPMODE Disabled, Falling Positive Input, VOD = 30 mV (T = 25°C)
VDD [V]
100
3
5
Propagation delay [ns]
80
60
40
20
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 549
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-59. Propagation Delay vs. VCM LPMODE Disabled, Rising Positive Input, VOD = 30 mV (T = 25°C)
VDD [V]
100
3
5
Propagation delay [ns]
80
60
40
20
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VCommon Mode [V]
OSC20M Characteristics
Figure 36-60. OSC20M Internal Oscillator: Calibration Stepsize vs. Calibration Value (VDD = 3V)
Temperature [°C]
2.5
-40
-20
0
25
70
85
105
125
2.3
2.0
Step size from 20 MHz [%]
36.8
1.8
1.5
1.3
1.0
0.8
0.5
0.3
0.0
0
8
16
24
32
40
48
56
64
OSCCAL [x1]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 550
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-61. OSC20M Internal Oscillator: Frequency vs. Calibration Value (VDD = 3V)
Temperature [°C]
30
-40
-20
0
25
70
85
105
125
28
26
Frequency [MHz]
24
22
20
18
16
14
12
10
0
8
16
24
32
40
48
56
64
OSCCAL [x1]
Figure 36-62. OSC20M Internal Oscillator: Frequency vs. Temperature
VDD [V]
20.5
1.8
2.2
2.7
3
3.6
5
5.5
20.4
20.3
Frequency [MHz]
20.2
20.1
20.0
19.9
19.8
19.7
19.6
19.5
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 551
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-63. OSC20M Internal Oscillator: Frequency vs. VDD
Temperature [°C]
20.5
-40
-20
0
25
70
85
105
125
20.4
20.3
Frequency [MHz]
20.2
20.1
20.0
19.9
19.8
19.7
19.6
19.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
OSCULP32K Characteristics
Figure 36-64. OSCULP32K Internal Oscillator Frequency vs. Temperature
VDD [V]
40.0
1.8
2.2
2.7
3
3.6
5
5.5
39.0
38.0
37.0
Frequency [kHz]
36.9
36.0
35.0
34.0
33.0
32.0
31.0
30.0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 552
ATtiny212/214/412/414/416
Typical Characteristics
Figure 36-65. OSCULP32K Internal Oscillator Frequency vs. VDD
Temperature [°C]
40.0
-40
-20
0
25
70
85
105
125
39.0
38.0
Frequency [kHz]
37.0
36.0
35.0
34.0
33.0
32.0
31.0
30.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VDD [V]
36.10
TWI SDA Hold Timing
Figure 36-66. TWI SDA Hold Time vs. Temperature (Client Mode) VDD = 3V, CLKCPU = 10 MHz
SDA Hold [ns]
1000
300
500
50
OFF
900
800
700
600
500
400
300
200
100
0
-40
-20
0
20
40
60
80
100
120
Temperature [°C]
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 553
ATtiny212/214/412/414/416
Ordering Information
37.
Ordering Information
•
37.1
Available ordering options can be found by:
– Clicking on one of the following product page links:
• ATtiny212 Product Page
• ATtiny214 Product Page
• ATtiny412 Product Page
• ATtiny414 Product Page
• ATtiny416 Product Page
– Searching by product name at microchipdirect.com
– Contacting the local sales representative
Product Information
Note: For the latest information on available ordering codes, refer to the ATtiny212/214/412/414/416 Silicon Errata
and Data Sheet Clarification(www.microchip.com/DS80000933) found on the product page.
Ordering Code(1)
Flash/SRAM
Pin Count
Max. CPU Speed
Supply Voltage
Package Type(2,3)
Temperature Range
ATtiny212-SSNR
2 KB/128B
8
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny212-SSN
2 KB/128B
8
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny212-SSFR
2 KB/128B
8
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny212-SSF
2 KB/128B
8
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny214-SSNR
2 KB/128B
14
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny214-SSN
2 KB/128B
14
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny214-SSFR
2 KB/128B
14
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny214-SSF
2 KB/128B
14
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny412-SSNR
4 KB/256B
8
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny412-SSN
4 KB/256B
8
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny412-SSFR
4 KB/256B
8
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny412-SSF
4 KB/256B
8
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny414-SSNR
4 KB/256B
14
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny414-SSN
4 KB/256B
14
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny414-SSFR
4 KB/256B
14
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny414-SSF
4 KB/256B
14
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
ATtiny416-MNR
4 KB/256B
20
20 MHz
1.8V-5.5V
VQFN
-40°C to +105°C
ATtiny416-MFR
4 KB/256B
20
16 MHz
2.7V-5.5V
VQFN
-40°C to +125°C
ATtiny416-SNR
4 KB/256B
20
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny416-SN
4 KB/256B
20
20 MHz
1.8V-5.5V
SOIC
-40°C to +105°C
ATtiny416-SFR
4 KB/256B
20
16 MHz
2.7V- 5.5V
SOIC
-40°C to +125°C
ATtiny416-SF
4 KB/256B
20
16 MHz
2.7V-5.5V
SOIC
-40°C to +125°C
Notes:
1. Pb-free packaging complies with the European Directive for Restriction of Hazardous Substances (RoHS
directive). Also, it is Halide free and fully Green.
2. Available in Tape & Reel, Tube or Tray packing media.
3. Package outline drawings can be found in section 38. Package Drawings.
37.2
Product Identification System
To order or obtain information, for example, on pricing or delivery, refer to the factory or the listed sales office.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 554
ATtiny212/214/412/414/416
Ordering Information
ATtiny416 - SFR
AVR® product family
Flash size in KB
tinyAVR® series
Pin count
6=20 pins
4=14 pins
2= 8 pins
© 2020 Microchip Technology Inc.
Carrier Type
R=Tape & Reel
Blank=Tube or Tray
Temperature Range
N=-40°C to +105°C
F=-40°C to +125°C
Package Type
M=VQFN
S=SOIC300
SS=SOIC150
Complete Datasheet
DS40002287A-page 555
ATtiny212/214/412/414/416
Package Drawings
38.
Package Drawings
38.1
Online Package Drawings
For the most recent package drawings:
1. Go to www.microchip.com/packaging.
2. Go to the package type-specific page, for example, VQFN.
3. Search for Drawing Number and Style to find the most recent package drawing.
Table 38-1. Drawing Numbers
Pin Count
Package Type
Drawing Number
Style
8
SOIC
C04-00057
SN
14
SOIC
C04-00065
SL
20
SOIC
C04-00094
SO
20
VQFN
C04-21380
REB
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 556
R
ATtiny212/214/412/414/416
Package Drawings
38.2
8-Pin SOIC
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
2X
0.10 C A–B
D
A
D
NOTE 5
N
E
2
E1
2
E1
E
2X
0.10 C A–B
2X
0.10 C A–B
NOTE 1
2
1
e
B
NOTE 5
NX b
0.25
C A–B D
TOP VIEW
0.10 C
C
A A2
SEATING
PLANE
8X
A1
SIDE VIEW
0.10 C
h
R0.13
h
R0.13
H
0.23
L
SEE VIEW C
(L1)
VIEW A–A
VIEW C
Microchip Technology Drawing No. C04-057-SN Rev F Sheet 1 of 2
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 557
ATtiny212/214/412/414/416
Package Drawings
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units
Dimension Limits
Number of Pins
N
e
Pitch
Overall Height
A
Molded Package Thickness
A2
§
Standoff
A1
Overall Width
E
Molded Package Width
E1
Overall Length
D
Chamfer (Optional)
h
Foot Length
L
L1
Footprint
Foot Angle
c
Lead Thickness
b
Lead Width
Mold Draft Angle Top
Mold Draft Angle Bottom
MIN
1.25
0.10
0.25
0.40
0°
0.17
0.31
5°
5°
MILLIMETERS
NOM
8
1.27 BSC
6.00 BSC
3.90 BSC
4.90 BSC
1.04 REF
-
MAX
1.75
0.25
0.50
1.27
8°
0.25
0.51
15°
15°
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic
3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or
protrusions shall not exceed 0.15mm per side.
4. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
5. Datums A & B to be determined at Datum H.
Microchip Technology Drawing No. C04-057-SN Rev F Sheet 2 of 2
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 558
ATtiny212/214/412/414/416
Package Drawings
8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
SILK SCREEN
C
Y1
X1
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
E
Contact Pitch
Contact Pad Spacing
C
Contact Pad Width (X8)
X1
Contact Pad Length (X8)
Y1
MIN
MILLIMETERS
NOM
1.27 BSC
5.40
MAX
0.60
1.55
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing C04-2057-SN Rev F
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 559
ATtiny212/214/412/414/416
R
Package Drawings
38.3
14-Pin SOIC
14-Lead Plastic Small Outline (SL) - Narrow, 3.90 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
2X
0.10 C A–B
D
A
NOTE 5
D
N
E
2
E2
2
E1
E
2X
0.10 C D
NOTE 1
1
2
2X N/2 TIPS
0.20 C
3
e
NX b
B
0.25
NOTE 5
C A–B D
TOP VIEW
0.10 C
C
A A2
SEATING
PLANE
14X
0.10 C
SIDE VIEW
A1
h
h
R0.13
H
R0.13
c
SEE VIEW C
L
VIEW A–A
(L1)
VIEW C
Microchip Technology Drawing No. C04-065-SL Rev D Sheet 1 of 2
© 2017 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 560
ATtiny212/214/412/414/416
Package Drawings
14-Lead Plastic Small Outline (SL) - Narrow, 3.90 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units
Dimension Limits
Number of Pins
N
e
Pitch
Overall Height
A
Molded Package Thickness
A2
§
Standoff
A1
Overall Width
E
Molded Package Width
E1
Overall Length
D
Chamfer (Optional)
h
Foot Length
L
Footprint
L1
Lead Angle
Foot Angle
c
Lead Thickness
Lead Width
b
Mold Draft Angle Top
Mold Draft Angle Bottom
MIN
1.25
0.10
0.25
0.40
0°
0°
0.10
0.31
5°
5°
MILLIMETERS
NOM
14
1.27 BSC
6.00 BSC
3.90 BSC
8.65 BSC
1.04 REF
-
MAX
1.75
0.25
0.50
1.27
8°
0.25
0.51
15°
15°
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. § Significant Characteristic
3. Dimension D does not include mold flash, protrusions or gate burrs, which shall
not exceed 0.15 mm per end. Dimension E1 does not include interlead flash
or protrusion, which shall not exceed 0.25 mm per side.
4. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
5. Datums A & B to be determined at Datum H.
Microchip Technology Drawing No. C04-065-SL Rev D Sheet 2 of 2
© 2017 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 561
ATtiny212/214/412/414/416
Package Drawings
14-Lead Plastic Small Outline (SL) - Narrow, 3.90 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
14
SILK SCREEN
C
Y
1
2
X
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
E
Contact Pitch
Contact Pad Spacing
C
Contact Pad Width (X14)
X
Contact Pad Length (X14)
Y
MIN
MILLIMETERS
NOM
1.27 BSC
5.40
MAX
0.60
1.55
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Microchip Technology Drawing No. C04-2065-SL Rev D
© 2017 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 562
ATtiny212/214/412/414/416
Package Drawings
38.4
20-Pin SOIC
20-Lead Plastic Small Outline (SO) - Wide, 7.50 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
D
A
E
2
E1
2
E1
E
2X 10 TIPS
0.33 C
NOTE 1
20X b
0.25
B
e
C A-B D
TOP VIEW
A
0.10 C
A2
A
C
SEATING
PLANE
20X
A1
SIDE VIEW
0.10 C
A
h
SEE DETAIL B
h
VIEW A–A
Microchip Technology Drawing C04-094 Rev D Sheet 1 of 2
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 563
ATtiny212/214/412/414/416
Package Drawings
20-Lead Plastic Small Outline (SO) - Wide, 7.50 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
θ2
θ1
R1
R
H
c
θ3
θ
L
(L1)
DETAIL B
Notes:
Number of Terminals
Pitch
Overall Height
Standoff
§
Molded Package Thickness
Overall Length
Overall Width
Molded Package Width
Terminal Width
Terminal Thickness
Corner Chamfer
Terminal Length
Footprint
Lead Bend Radius
Lead Bend Radius
Foot Angle
Lead Angle
Mold Draft Angle
Mold Draft Angle
Units
Dimension Limits
N
e
A
A1
A2
D
E
E1
b
c
h
L
L1
R1
R2
θ
θ1
θ2
θ3
MIN
0.10
2.05
0.31
0.25
0.25
0.41
0.07
0.07
0°
0°
5°
5°
MILLIMETERS
NOM
20
1.27 BSC
12.80 BSC
10.30 BSC
7.50 BSC
0.65
1.40 REF
-
MAX
2.65
0.30
-
0.51
0.75
0.41
0.89
8°
15°
15°
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
3. Dimension D does not include mold flash, protrusions or gate burrs, which shall
not exceed 0.15 mm per end. Dimension E1 does not include interlead flash
or protrusion, which shall not exceed 0.25 mm per side.
4. § Significant Characteristic
Microchip Technology Drawing C04-094 Rev D Sheet 2 of 2
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 564
ATtiny212/214/412/414/416
Package Drawings
20-Lead Plastic Small Outline (SO) - Wide, 7.50 mm Body [SOIC]
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
G1
20
SILK SCREEN
C
G
Y
1
2
X
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
Contact Pitch
E
Contact Pad Spacing
C
Contact Pad Width (X20)
X
Contact Pad Length (X20)
Y
Contact Pad to Contact Pad
G
Contact Pad to Contact Pad
G1
MIN
MILLIMETERS
NOM
1.27 BSC
9.40
MAX
0.60
1.95
0.67
7.45
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
2. For best soldering results, thermal vias, if used, should be filled or tented to avoid solder loss during
reflow process
Microchip Technology Drawing C04-2094 Rev D
© 2020 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 565
ATtiny212/214/412/414/416
Package Drawings
38.5
20-Pin VQFN
20-Lead Very Thin Plastic Quad Flat, No Lead Package (REB) - 3x3 mm Body [VQFN]
With 1.7 mm Exposed Pad; Atmel Legacy Global Package Code ZCL
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
16X
0.08 C
D
NOTE 1
A
0.10 C
B
N
1
2
E
(DATUM B)
(DATUM A)
2X
0.10 C
2X
A1
TOP VIEW
0.10 C
0.10
(A3)
C A B
A
SEATING
C
PLANE
D2
SIDE VIEW
0.10
C A B
E2
2
(CH)
1
NOTE 1
K
N
L
e
BOTTOM VIEW
20X b
0.10
0.05
C A B
C
Microchip Technology Drawing C04-21380 Rev A Sheet 1 of 2
© 2018 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 566
ATtiny212/214/412/414/416
Package Drawings
20-Lead Very Thin Plastic Quad Flat, No Lead Package (REB) - 3x3 mm Body [VQFN]
With 1.7 mm Exposed Pad; Atmel Legacy Global Package Code ZCL
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Notes:
Units
Dimension Limits
Number of Terminals
N
e
Pitch
A
Overall Height
Standoff
A1
A3
Terminal Thickness
Overall Length
D
Exposed Pad Length
D2
Overall Width
E
Exposed Pad Width
E2
b
Terminal Width
Terminal Length
L
Terminal-to-Exposed-Pad
K
Pin 1 Index Chamfer
CH
MIN
0.80
0.00
1.60
1.60
0.15
0.35
0.20
MILLIMETERS
NOM
20
0.40 BSC
0.85
0.035
0.203 REF
3.00 BSC
1.70
3.00 BSC
1.70
0.20
0.40
0.35 REF
MAX
0.90
0.05
1.80
1.80
0.25
0.45
-
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Package is saw singulated
3. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Microchip Technology Drawing C04-21380 Rev A Sheet 2 of 2
© 2018 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 567
ATtiny212/214/412/414/416
Package Drawings
20-Lead Very Thin Plastic Quad Flat, No Lead Package (REB) - 3x3 mm Body [VQFN]
With 1.7 mm Exposed Pad; Atmel Legacy Global Package Code ZCL
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
C1
X2
EV
ØV
G2
C2 Y2 EV
G1
Y1
X1
SILK SCREEN
E
RECOMMENDED LAND PATTERN
Units
Dimension Limits
E
Contact Pitch
Optional Center Pad Width
X2
Optional Center Pad Length
Y2
Contact Pad Spacing
C1
Contact Pad Spacing
C2
Contact Pad Width (X20)
X1
Contact Pad Length (X20)
Y1
Contact Pad to Center Pad (X20)
G1
Contact Pad to Contact Pad (X16)
G2
Thermal Via Diameter
V
Thermal Via Pitch
EV
MIN
MILLIMETERS
NOM
0.40 BSC
MAX
1.80
1.80
3.00
3.00
0.20
0.80
0.20
0.20
0.30
1.00
Notes:
1. Dimensioning and tolerancing per ASME Y14.5M
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
2. For best soldering results, thermal vias, if used, should be filled or tented to avoid solder loss during
reflow process
Microchip Technology Drawing C04-23380 Rev A
© 2018 Microchip Technology Inc.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 568
ATtiny212/214/412/414/416
Package Drawings
38.6
38.6.1
Thermal Considerations
Thermal Resistance Data
The following table summarizes the thermal resistance data depending on the package.
Table 38-2. Thermal Resistance Data
38.6.2
Pin Count
Package Type
θJA [°C/W]
θJC [°C/W]
8
SOIC
91.8
21.5
14
SOIC
58
26
20
SOIC
44
21
20
VQFN
79.7
36
Junction Temperature
The average chip-junction temperature, TJ, in °C, can be obtained from the following equations:
•
•
Equation 1: TJ = TA + (PD x θJA)
Equation 2: TJ = TA + (PD x (θHEATSINK + θJC))
where:
•
•
•
•
•
θJA = Package thermal resistance, Junction-to-ambient (°C/W), see Table 38-2
θJC = Package thermal resistance, Junction-to-case thermal resistance (°C/W), see Table 38-2
θHEATSINK = Thermal resistance (°C/W) specification of the external cooling device
PD = Device power consumption (W)
TA = Ambient temperature (°C)
From the first equation, the user can derive the estimated lifetime of the chip and decide whether a cooling device is
necessary or not. If a cooling device has to be fitted on the chip, the second equation must be used to compute the
resulting average chip-junction temperature TJ in °C.
Power usage can be calculated by adding together system power consumption and I/O module power consumption.
The current drawn from pins with a capacitive load may be estimated (for one pin) as follows:
Icp ≈ VDD * Cload * fsw
Where Cload = pin load capacitance and fsw = average switching frequency of I/O pin.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 569
ATtiny212/214/412/414/416
Errata
39.
Errata
39.1
Errata - ATtiny212/214/412/414/416
Errata can be found in the ATtiny212/214/412/414/416 Silicon Errata and Data Sheet
Clarification(www.microchip.com/DS80000933).
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 570
ATtiny212/214/412/414/416
Data Sheet Revision History
40.
Data Sheet Revision History
Note: The data sheet revision is independent of the die revision and the device variant (last letter of the ordering
number).
40.1
Rev. A - 12/2020
Section
Document
Changes
•
Initial document release
The content for the devices described in this document has been restructured from:
• ATtiny212/412 Data Sheet
• ATtiny214/414/814 Data Sheet
• ATtiny416/816 Data Sheet
• ATtiny417/817 Data Sheet
to:
•
•
ATtiny212/214/412/414/416 Data Sheet (this document)
ATtiny417/814/816/817 Data Sheet
Refer to 40.2 Appendix - Obsolete Revision History for further details.
The following items are referring to changes between the latest revisions of the obsolete
documents and this document:
•
•
•
•
•
•
•
Updated the document to Microchip editing standard
Updated terminology used throughout data sheet:
– Master is replaced by host
– Slave is replaced by client
Removed related links
Removed the Acronyms and Abbreviations section
Removed the content of the Instruction Set Summary section. This section now refers to
the external Instruction Set Manual instead.
Removed device-specific information from peripheral sections
Restructured sections related to system dependencies within the peripheral sections
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 571
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Device
Changes
•
•
•
•
•
•
AVR CPU
•
•
•
•
•
•
•
•
Device-specific information is restructured/changed to comply with the devices
documented in this document
– Features
– Pinout
– I/O Multiplexing and Considerations
– Ordering Information
– Package Drawings
Block diagram updated
Pinout diagrams updated:
– 8-Pin SOIC
– 14-Pin SOIC
– 20-Pin SOIC
– 20-Pin VQFN
Memories
– Flash and the Three Sections figure added(3)
– Memory Map figure updated
– Memory Section Access from CPU and UPDI on Locked Device section added
– Fuse Description section updated with factory-programmed default values
Peripherals and Architecture
– Peripheral Address Match table updated
– Interrupt Vector Mapping table updated
• Base Address column renamed to Program Address (word)
• Peripheral Source column cleaned up
• Definition column renamed to Description and cleaned up
Package Drawings
– Drawing Numbers table updated
– Tables removed as the information is available on the Microchip website:
• Device Package and Maximum Weight
• Package Characteristics
• Package Reference
– Thermal Considerations section updated and moved inside the Package Drawings
section
Updated Features section
Removed duplicate information after the AVR CPU architecture
Emphasized that the Arithmetic Logic Unit (ALU) is doing its operations against working
registers in the register file
Added Stack Pointer Instructions table
Restructured and improved documentation in the following sections:
– Register File
– X-, Y-, and Z-Registers
– Accessing 16-bit Registers
Added Accessing 24-Bit Registers section
Added On-Chip Debug Capabilities section
Updated bit names in the Status Register (SREG):
– From Bit Copy Storage to Transfer Bit
– From Sign Bit to Sign Flag
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 572
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
NVMCTRL
•
•
Updated NVMCTRL Block Diagram figure
Write Access After Reset section added
CLKCTRL
•
•
•
•
•
•
•
•
Updated CLKCTRL Block Diagram figure(1,2)
Updated Signal Description section(1,2)
Updated Main Clock and Prescaler figure(1)
Updated External Clock Sources section(1)
Added 32.768 kHz Crystal Oscillator (XOSC32K) section(1)
Updated CLKSEL bit field in MCLKCTRLA register(1)
Added XOSC32KS bit in MCLKSTATUS(1)
Added XOSC32KCTRLA register(1)
SLPCTRL
•
Updated Sleep Mode Activity Overview tables
RSTCTRL
•
•
•
Updated Block Diagram figure
Figures added:
– MCU Start-up, RESET Tied to VDD
– Brown-out Detector Reset
– External Reset Characteristics
– Watchdog Reset
– Software Reset
Added Domains Affected By Reset section
CPUINT
•
•
Added Minimum Interrupt Response Time table
General improvement of the documentation and its structure
EVSYS
•
Register names updated
– From ASYNCCH to ASYNCCHn
– From SYNCCH to SYNCCHn
– From ASYNCUSER to ASYNCUSERn
– From SYNCUSER to SYNCUSERn
Bit field descriptions updated
– ASYNCCHn.ASYNCCH
– SYNCCHn.SYNCCH
•
PORT
•
•
•
•
Updated Block Diagram figure
Added Asynchronous Sensing Pin Properties added
Added Event Generators in PORTx table
General improvement of the documentation and its structure
BOD
•
•
•
Block diagram updated
Offset in the Available Interrupt Vectors and Sources table removed
Name column added to bit field description tables:
– CTRLA.ACTIVE
– CTRLA.SLEEP
– INTCTRL.VLMCFG
WDT
•
Updated values in the CTRLA.PERIOD bit field description
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 573
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
TCA
Changes
•
•
•
•
•
•
•
•
•
•
•
TCB
•
•
•
•
•
•
•
TCD
•
•
•
•
•
•
Updated Block Diagram figure
Updated Timer/Counter Clock Logic figure
Updated Signal Description table
Update Single-Slope Pulse-Width Modulation figure
Updated Timer/Counter Block Diagram Split Mode figure
Added Event Generators in TCA table
Added Event Users in TCA table
Removed offset in the Available Interrupt Vectors and Sources in Normal Mode and
Available Interrupt Vectors and Sources in Split mode tables
Combined tables for the CTRLB.WGMODE bit field into one
Added bit fields:
– CTRLECLR.CMDEN
– CTRLESET.CMDEN
General improvement of the documentation and its structure
Updated Block Diagram figure
Timer/Counter Clock Logic figure added
Figures updated:
– Periodic Interrupt Mode
– Time-Out Check Mode
– Input Capture on Event
– Input Capture Frequency Measurement
– Input Capture Pulse-Width Measurement
– Input Capture Frequency and Pulse-Width Measurement
– Single-Shot Mode
– 8-Bit PWM Mode
Added Event Generators in TCB table
Added Event Users and Available Event Actions in TCB table
Removed offset in the Available Interrupt Vectors and Sources table
Name column added to bit field description tables:
– CTRLA.CLKSEL
– CTRLB.CNTMODE
Updated Block Diagram figure
Added Event Generators in TCD table
Added Event Users and Available Event Actions in TCD table
Removed offset in the Available Interrupt Vectors and Sources table
Added name column to bit field description tables:
– CTRLA.CLKSEL
– CTRLA.CNTPRES
– CTRLA.SYNCPRES
– CTRLA.ENABLE
– DLYCTRL.DLYPRESC
– DLYCTRL.DLYSEL
General improvement of the documentation and its structure
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 574
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
RTC
•
•
•
•
•
Updated Block Diagram figure
Event Generators in RTC table added
Removed offset in the Available Interrupt Vectors and Sources table
Added name column to the bit field description table for CLKSEL.CLKSEL
General improvement of the documentation and its structure
USART
•
Added information about TXD buffer in:
– Block Diagram figure
– Overview section
– Data Transmission section
Event Generators in USART table added
Event Users in USART table added
Offset in the Available Interrupt Vectors and Sources table removed
General improvement of the documentation and its structure
Updated terminology:
– Master is replaced by host
– Slave is replaced by client
•
•
•
•
•
SPI
•
•
•
•
•
•
Updated Block Diagram figure
Added Event Generators in SPI table
Removed offset in the Available Interrupt Vectors and Sources table
Interrupt Flags register separate for Normal and Buffer mode
General improvement of the documentation and its structure
Updated terminology:
– Master is replaced by host
– Slave is replaced by client
TWI
•
•
Offset in the Available Interrupt Vectors and Sources table removed
Name column added to bit field description tables:
– CTRLA.FMPEN
– MCTRLB.ACKACT
– MCTRLB.MCMD
General improvement of the documentation and its structure
Updated terminology:
– Master is replaced by host
– Slave is replaced by client
•
•
CRCSCAN
•
•
Updated Block Diagram figure(1)
Offset in the Available Interrupt Vectors and Sources table removed
CCL
•
•
•
•
Updated Block Diagram figure
Replaced Lookup Table Logic section with Truth Table Logic section
Updated Clock Source Settings figure
Updated bit field description of TRUTHn.TRUTHn
AC
•
DACREF removed as an internal input
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 575
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
ADC
•
•
•
•
•
Updated Block Diagram figure
Moved Definitions to ADC Parameter Definitions in Conventions section
Removed PTC Operation section(2,3)
Removed offset in the Available Interrupt Vectors and Sources table
Updated the CTRLA.MUXPOS bit field description
DAC
•
Removed repeating notes "Only DAC0 has an output driver for an external pin"
PTC
•
PTC section removed (2,3)
UPDI
•
Updated figures:
– UPDI Clock Domains
– UPDI Instruction Set Overview
– LDS Instruction Operation
– STS Instruction Operation
– LD Instruction Operation
– ST Instruction Operation
– LCDS Instruction Operation
– STCS Instruction Operation
– REPEAT Instruction Operation
– Inter Delay Example with LD and RPT
Added sections:
– BREAK in One-Wire mode
– SYNCH and SYNCH in One-Wire mode
Extended and improved the documentation related to enabling the UPDI peripheral
Extended and improved the documentation related to disabling the UPDI peripheral
Renamed the UPDI Enable with 12V Override of RESET pin section to UPDI Enable with
High-Voltage Override of RESET pin
Added the REPEAT Used With LD Instruction Operation figure
Added Event Generators in UPDI table
Removed implementation-specific details that are considered as not useful for the end
users
•
•
•
•
•
•
•
Electrical
Characterization
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Added Maximum Frequency vs. VDD for [-40, 125]°C, Extended Temperature Range figure
Added maximum numbers to the Power Consumption section
Rounded numbers in the Peripherals Power Consumption table
Added TCD section
Updated TWI - Timing Requirements figure
Updated numbers for tOF in the TWI - Timing Characteristics table
Added typical values for tHD;STA, tSU;STA, tSU;STO and tBUF
Added SDA Hold Time table
Added TEMPSENSE section
Updated Accuracy Characteristics table for DAC
Updated tables in the AC section
Removed PTC section(2,3)
Added UPDI Max. Bit Rates vs. VDD table
Replaced Chip Erase with Chip Erase with UPDI in the Programming Times table
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 576
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Typical
Characterization
Changes
•
•
•
•
Updated Power Consumption plots
Added Temperature Sensor Error vs. Temperature ±3σ figure
Added TWI SDA Hold Time vs. Temperature figure
Removed PTC Characteristics section(2,3)
Notes:
1. Change only applies when compared to ATtiny212/412 Data Sheet (DS40001911C).
2. Change only applies when compared to ATtiny412/414/814 Data Sheet (DS40001912C).
3. Change only applies when compared to ATtiny416/816 Data Sheet (DS40001913C).
40.2
Appendix - Obsolete Revision History
Notes: Due to document structure change from pin organized documents, the following document history is
provided as reference.
• ATtiny212/412 Data Sheet (DS40001911C).
• ATtiny412/414/814 Data Sheet (DS40001912C)
• ATtiny416/816 Data Sheet (DS40001913C)
40.2.1
ATtiny212/412 - DS40001911
Obsolete Publication DS40001911C - 10/2019
Section
Changes
Document
•
Added Preliminary prefix to data sheet
CLKCTRL
•
Removed reference to CLKOUT
Electrical Characteristics
•
•
Updated characteristics for AC Hysteresis
ADC Characteristics:
– Added duty cycle note for clock frequencies above 1500 kHz
Obsolete Publication DS40001911B - 07/2019
Section
Changes
Document
•
Editorial updates.
Device
•
Introduction:
– Added a note for automotive data sheets
– Changed text to align with all tinyAVR® 0- and
1-series data sheets
Retention endurance numbers added
Data Sheet Clarification Document chapter added
Ordering Information moved
I/O Multiplexing and Considerations updated
Removed references to unsupported external 32
kHz oscillator
•
•
•
•
•
Configuration and User Fuses
© 2020 Microchip Technology Inc.
•
RSTPINCFG: Time-out after a system reset when
fused to be GPIO explained
Complete Datasheet
DS40002287A-page 577
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
PORTMUX
•
Updated with missing information
BOD - Brown-out Detector
•
Removed levels not characterized by minimum and
maximum values
Added a note for typical values and reference to
electrical characteristics
•
TCA
•
Added a note for alternative WOn pins
USART
•
•
•
Clarified One-Wire mode
Clarified text about Disabling the Transmitter
Reverted 32±6 to 16±3 baud samples in RXMODE
bits in CTRLB
SPI
•
Clarified functionality for SPI SS pin
CRCSCAN
•
Removed unsupported BACKGROUND and
CONTINUOUS scan functionality
ADC - Analog-to-Digital Converter
•
Added missing calibration register
UPDI
•
•
Added warning for ESD protection
GPIO functionality disabled for a period after a
system reset, changed from ms to clock cycles
Electrical Characteristics
•
Added note for Chip Erase in General Operating
Ratings
Corrected the description for some symbols in the
I/O Pin Characteristics table
•
Errata
•
Errata moved to ATtiny212/412 Silicon Errata and
Data Sheet Clarification Document
Ordering Information
•
Updated with product page links and ordering
codes
Product Identification System
•
Updated with Tube and Tray packing media
Package Drawings
•
Updated package drawings to Microchip standard
Obsolete Publication DS40001911A - 01/2017
40.2.2
Section
Changes
Document
Initial Release
ATtiny214/414/814 - DS40001912
Obsolete Publication DS40001912C - 10/2019
Section
Changes
Document
•
Reverted data sheet status from complete to preliminary
Block Diagram
•
Removed unsupported CLKOUT
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 578
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
CLKCTRL
•
Removed unsupported CLKOUT in block diagram, signal description and
MCLKCTRLA register
Electrical Characteristics
•
•
Removed max./min. characteristics for AC Hysteresis
ADC Characteristics:
– Added duty cycle note for clock frequencies above 1500 kHz
PTC Characteristics - Operating Ratings:
– Removed VDD and CLKPER characteristics
– Added CLKADC characteristics
•
Obsolete Publication DS40001912B - 07/2019
Section
Changes
Document
•
Editorial updates.
Device
•
•
•
•
•
Introduction:
– Added a note for automotive data sheets
– Changed text to align with all tinyAVR® 0- and 1-series data sheets
Retention endurance numbers added
Data Sheet Clarification Document chapter added
Ordering Information moved
I/O Multiplexing and Considerations updated
Configuration and User
Fuses
•
RSTPINCFG: Time-out after a system reset when fused to be GPIO explained
PORTMUX
•
Updated with missing information
BOD - Brown-out Detector
•
•
Removed levels not characterized by minimum and maximum values
Added a note for typical values and reference to electrical characteristics
TCA
•
Added a note for alternative WOn pins
USART
•
•
•
Clarified One-Wire mode
Clarified text about Disabling the Transmitter
Reverted 32±6 to 16±3 baud samples in RXMODE bits in CTRLB
SPI
•
Clarified functionality for SPI SS pin
CRCSCAN
•
Removed unsupported BACKGROUND and CONTINUOUS scan functionality
ADC - Analog-to-Digital
Converter
•
Added missing calibration register
UPDI
•
•
Added a warning for ESD protection
GPIO functionality disabled for a period after a system reset, changed from ms to
clock cycles
Electrical Characteristics
•
•
Added a note for Chip Erase in General Operating Ratings
Corrected the description for some symbols in the I/O Pin Characteristics table
Errata
•
Errata moved to ATtiny214/414/814 Silicon Errata and Data Sheet Clarification
Document
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 579
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
Ordering Information
•
Updated with product page links and ordering codes
Product Identification
System
•
Updated with Tube and Tray packing media
Package Drawings
•
Updated package drawings to Microchip standard
Obsolete Publication DS40001912A - 01/2017
40.2.3
Section
Changes
Document
Initial Release
ATtiny416/816 - DS40001913
Obsolete Publication DS40001913C - 10/2019
Section
Changes
Document
•
Reverted data sheet status from complete to preliminary
Electrical Characteristics
•
•
Removed max./min. characteristics for AC Hysteresis
ADC Characteristics:
– Added duty cycle note for clock frequencies above 1500 kHz
PTC Characteristics - Operating Ratings:
– Removed VDD and CLKPER characteristics
– Added CLKADC characteristics
•
Obsolete Publication DS40001913B - 07/2019
Section
Changes
Document
•
Editorial updates.
Device
•
Introduction:
– Added a note for automotive data sheets
– Changed text to align with all tinyAVR® 0- and
1-series data sheets
Retention endurance numbers added
Data Sheet Clarification Document chapter added
Ordering Information moved
I/O Multiplexing and Considerations updated
•
•
•
•
Configuration and User Fuses
•
RSTPINCFG: Time-out after a system reset when
fused to be GPIO explained
BOD - Brown-out Detector
•
Removed levels not characterized by minimum and
maximum values
Added a note for typical values and reference to
electrical characteristics
•
TCA
© 2020 Microchip Technology Inc.
•
Added a note for alternative WOn pins
Complete Datasheet
DS40002287A-page 580
ATtiny212/214/412/414/416
Data Sheet Revision History
...........continued
Section
Changes
USART
•
•
•
Clarified One-Wire mode
Clarified text about Disabling the Transmitter
Reverted 32±6 to 16±3 baud samples in RXMODE
bits in CTRLB
SPI
•
Clarified functionality for SPI SS pin
CRCSCAN
•
Removed unsupported BACKGROUND and
CONTINUOUS scan functionality
ADC - Analog-to-Digital Converter
•
Added missing calibration register
UPDI
•
•
Added a warning for ESD protection
GPIO functionality disabled for a period after a
system reset, changed from ms to clock cycles
Electrical Characteristics
•
Added a note for Chip Erase in General Operating
Ratings
Added Electrical Characteristics for PTC
Corrected the description for some symbols in the
I/O Pin Characteristics table
•
•
Errata
•
Errata moved to ATtiny416/816 Silicon Errata and
Data Sheet Clarification Document
Ordering Information
•
Updated with product page links and ordering
codes
Product Identification System
•
Updated with Tube and Tray packing media
Package Drawings
•
Updated package drawings to Microchip standard
Obsolete Publication DS40001913A - 01/2017
Section
Changes
Document
Initial Release
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 581
ATtiny212/214/412/414/416
The Microchip Website
Microchip provides online support via our website at www.microchip.com/. This website is used to make files and
information easily available to customers. Some of the content available includes:
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Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s
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To register, go to www.microchip.com/pcn and follow the registration instructions.
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Users of Microchip products can receive assistance through several channels:
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Customers should contact their distributor, representative or ESE for support. Local sales offices are also available to
help customers. A listing of sales offices and locations is included in this document.
Technical support is available through the website at: www.microchip.com/support
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 582
ATtiny212/214/412/414/416
Product Identification System
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
ATtiny416 - SFR
AVR® product family
Flash size in KB
tinyAVR® series
Pin count
6=20 pins
4=14 pins
2= 8 pins
Carrier Type
R=Tape & Reel
Blank=Tube or Tray
Temperature Range
N=-40°C to +105°C
F=-40°C to +125°C
Package Type
M=VQFN
S=SOIC300
SS=SOIC150
Note: Tape and Reel identifier only appears in the catalog part number description. This identifier is used for
ordering purposes. Check with your Microchip Sales Office for package availability with the Tape and Reel option.
Microchip Devices Code Protection Feature
Note the following details of the code protection feature on Microchip devices:
•
•
•
•
•
Microchip products meet the specifications contained in their particular Microchip Data Sheet.
Microchip believes that its family of products is secure when used in the intended manner and under normal
conditions.
There are dishonest and possibly illegal methods being used in attempts to breach the code protection features
of the Microchip devices. We believe that these methods require using the Microchip products in a manner
outside the operating specifications contained in Microchip’s Data Sheets. Attempts to breach these code
protection features, most likely, cannot be accomplished without violating Microchip’s intellectual property rights.
Microchip is willing to work with any customer who is concerned about the integrity of its code.
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of its code. Code
protection does not mean that we are guaranteeing the product is “unbreakable.” Code protection is constantly
evolving. We at Microchip are committed to continuously improving the code protection features of our products.
Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act.
If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue
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and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 583
ATtiny212/214/412/414/416
expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual
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The Microchip name and logo, the Microchip logo, Adaptec, AnyRate, AVR, AVR logo, AVR Freaks, BesTime,
BitCloud, chipKIT, chipKIT logo, CryptoMemory, CryptoRF, dsPIC, FlashFlex, flexPWR, HELDO, IGLOO, JukeBlox,
KeeLoq, Kleer, LANCheck, LinkMD, maXStylus, maXTouch, MediaLB, megaAVR, Microsemi, Microsemi logo, MOST,
MOST logo, MPLAB, OptoLyzer, PackeTime, PIC, picoPower, PICSTART, PIC32 logo, PolarFire, Prochip Designer,
QTouch, SAM-BA, SenGenuity, SpyNIC, SST, SST Logo, SuperFlash, Symmetricom, SyncServer, Tachyon,
TimeSource, tinyAVR, UNI/O, Vectron, and XMEGA are registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AgileSwitch, APT, ClockWorks, The Embedded Control Solutions Company, EtherSynch, FlashTec, Hyper Speed
Control, HyperLight Load, IntelliMOS, Libero, motorBench, mTouch, Powermite 3, Precision Edge, ProASIC, ProASIC
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TimeProvider, WinPath, and ZL are registered trademarks of Microchip Technology Incorporated in the U.S.A.
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dsPICDEM, dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, Espresso T1S, EtherGREEN, IdealBridge, InCircuit Serial Programming, ICSP, INICnet, Intelligent Paralleling, Inter-Chip Connectivity, JitterBlocker, maxCrypto,
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GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip
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All other trademarks mentioned herein are property of their respective companies.
©
2020, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.
ISBN: 978-1-5224-7298-8
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For information regarding Microchip’s Quality Management Systems, please visit www.microchip.com/quality.
© 2020 Microchip Technology Inc.
Complete Datasheet
DS40002287A-page 584
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Complete Datasheet
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