C8051F310/1/2/3/4/5/6/7
8/16 kB ISP Flash MCU Family
Analog Peripherals
- 10-Bit ADC (C8051F310/1/2/3/6 only)
•
•
•
•
•
-
High Speed 8051 µC Core
- Pipelined instruction architecture; executes 70% of
Up to 200 ksps
Up to 21, 17, or 13 external single-ended or differential inputs
VREF from external pin or VDD
Built-in temperature sensor
External conversion start input
Comparators
•
•
•
Programmable hysteresis and response time
Configurable as interrupt or reset source (Comparator0)
Low current ( 0.5 µA)
On-Chip Debug
- On-chip debug circuitry facilitates full speed,
-
non-intrusive in-system debug
(no emulator required)
Provides breakpoints, single stepping,
inspect/modify memory and registers
Superior performance to emulation systems using
ICE-Chips, target pods, and sockets
Complete development kit
Supply Voltage 2.7 to 3.6 V
- Typical operating current:
5 mA at 25 MHz;
-
Typical stop mode current:
Temperature range:
instructions in 1 or 2 system clocks
- Up to 25 MIPS throughput with 25 MHz clock
- Expanded interrupt handler
Memory
- 1280 bytes internal data RAM (1024 + 256)
- 16 kB (C8051F310/1/6/7) or 8 kB (C8051F312/3/4/5)
Flash; In-system programmable in 512-byte sectors
Digital Peripherals
- 29/25/21 Port I/O;
-
All 5 V tolerant with high sink current
Hardware enhanced UART, SMBus™, and SPI™
serial ports
Four general purpose 16-bit counter/timers
16-bit programmable counter array (PCA) with five
capture/compare modules
Real time clock capability using PCA or timer and
external clock source
Clock Sources
- Internal oscillator: 24.5 MHz with ±2% accuracy
11 µA at 32 kHz
0.1 µA
–40 to +85 °C
-
supports crystal-less UART operation
External oscillator: Crystal, RC, C, or clock (1 or 2
pin modes)
Can switch between clock sources on-the-fly; useful
in power saving modes
Packages
- 32-pin LQFP (C8051F310/2/4)
- 28-pin QFN (C8051F311/3/5)
- 24-pin QFN (C8051F316/7)
A
M
U
X
10-bit
200ksps
ADC
TEMP
SENSOR
C8051F310/1/2/3/6 only
+
+
VOLTAGE
COMPARATORS
DIGITAL I/O
UART
SMBus
SPI
PCA
Timer 0
Timer 1
Timer 2
Timer 3
CROSSBAR
ANALOG
PERIPHERALS
Port 0
Port 1
Port 2
Port 3
PROGRAMMABLE PRECISION INTERNAL
OSCILLATOR
HIGH-SPEED CONTROLLER CORE
16 kB/8 kB
ISP FLASH
14
INTERRUPTS
Rev. 1.8 10/17
8051 CPU
(25MIPS)
DEBUG
CIRCUITRY
1280 B
SRAM
POR
Copyright © 2017 by Silicon Laboratories
WDT
C8051F31x
C8051F310/1/2/3/4/5/6/7
NOTES:
2
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Table Of Contents
1. System Overview.................................................................................................... 17
1.1. CIP-51™ Microcontroller Core.......................................................................... 27
1.1.1. Fully 8051 Compatible.............................................................................. 27
1.1.2. Improved Throughput ............................................................................... 27
1.1.3. Additional Features .................................................................................. 28
1.2. On-Chip Memory............................................................................................... 29
1.3. On-Chip Debug Circuitry................................................................................... 30
1.4. Programmable Digital I/O and Crossbar ........................................................... 31
1.5. Serial Ports ....................................................................................................... 32
1.6. Programmable Counter Array ........................................................................... 32
1.7. 12-Bit Analog to Digital Converter..................................................................... 33
1.8. Comparators ..................................................................................................... 34
2. Absolute Maximum Ratings .................................................................................. 35
3. Global DC Electrical Characteristics .................................................................... 36
4. Pinout and Package Definitions............................................................................ 39
5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only) ........................................................ 51
5.1. Analog Multiplexer ............................................................................................ 51
5.2. Temperature Sensor ......................................................................................... 52
5.3. Modes of Operation .......................................................................................... 54
5.3.1. Starting a Conversion............................................................................... 54
5.3.2. Tracking Modes........................................................................................ 55
5.3.3. Settling Time Requirements ..................................................................... 56
5.4. Programmable Window Detector ...................................................................... 61
5.4.1. Window Detector In Single-Ended Mode ................................................. 63
5.4.2. Window Detector In Differential Mode...................................................... 64
6. Voltage Reference (C8051F310/1/2/3/6 only)........................................................ 67
7. Comparators ........................................................................................................... 69
8. CIP-51 Microcontroller .......................................................................................... 79
8.1. Instruction Set ................................................................................................... 80
8.1.1. Instruction and CPU Timing ..................................................................... 80
8.1.2. MOVX Instruction and Program Memory ................................................. 81
8.2. Memory Organization........................................................................................ 85
8.2.1. Program Memory...................................................................................... 85
8.2.2. Data Memory............................................................................................ 86
8.2.3. General Purpose Registers ...................................................................... 86
8.2.4. Bit Addressable Locations........................................................................ 86
8.2.5. Stack ....................................................................................................... 86
8.2.6. Special Function Registers....................................................................... 87
8.2.7. Register Descriptions ............................................................................... 90
8.3. Interrupt Handler ............................................................................................... 93
8.3.1. MCU Interrupt Sources and Vectors ........................................................ 94
8.3.2. External Interrupts .................................................................................... 95
8.3.3. Interrupt Priorities ..................................................................................... 95
Rev. 1.8
3
C8051F310/1/2/3/4/5/6/7
8.3.4. Interrupt Latency ...................................................................................... 95
8.3.5. Interrupt Register Descriptions................................................................. 97
8.4. Power Management Modes ............................................................................ 102
8.4.1. Idle Mode................................................................................................ 102
8.4.2. Stop Mode .............................................................................................. 103
9. Reset Sources....................................................................................................... 105
9.1. Power-On Reset ............................................................................................. 106
9.2. Power-Fail Reset / VDD Monitor..................................................................... 106
9.3. External Reset ................................................................................................ 107
9.4. Missing Clock Detector Reset......................................................................... 108
9.5. Comparator0 Reset......................................................................................... 108
9.6. PCA Watchdog Timer Reset........................................................................... 108
9.7. Flash Error Reset............................................................................................ 108
9.8. Software Reset ............................................................................................... 108
10. Flash Memory ..................................................................................................... 111
10.1.Programming The Flash Memory ................................................................... 111
10.1.1.Flash Lock and Key Functions ............................................................... 111
10.1.2.Flash Erase Procedure .......................................................................... 111
10.1.3.Flash Write Procedure ........................................................................... 112
10.2.Non-volatile Data Storage .............................................................................. 112
10.3.Security Options ............................................................................................. 113
10.4.Flash Write and Erase Guidelines .................................................................. 115
10.4.1.VDD Maintenance and the VDD Monitor ................................................. 115
10.4.2.PSWE Maintenance ............................................................................... 115
10.4.3.System Clock ......................................................................................... 116
11. External RAM ........................................................................................................ 119
12. Oscillators ............................................................................................................. 121
12.1.Programmable Internal Oscillator ................................................................... 121
12.2.External Oscillator Drive Circuit...................................................................... 124
12.3.System Clock Selection.................................................................................. 124
12.4.External Crystal Example ............................................................................... 126
12.5.External RC Example ..................................................................................... 127
12.6.External Capacitor Example ........................................................................... 127
13. Port Input/Output ................................................................................................ 129
13.1.Priority Crossbar Decoder .............................................................................. 131
13.2.Port I/O Initialization ....................................................................................... 133
13.3.General Purpose Port I/O ............................................................................... 135
14. SMBus ................................................................................................................... 145
14.1.Supporting Documents ................................................................................... 146
14.2.SMBus Configuration...................................................................................... 146
14.3.SMBus Operation ........................................................................................... 146
14.3.1.Arbitration............................................................................................... 147
14.3.2.Clock Low Extension.............................................................................. 148
14.3.3.SCL Low Timeout................................................................................... 148
14.3.4.SCL High (SMBus Free) Timeout .......................................................... 148
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C8051F310/1/2/3/4/5/6/7
14.4.Using the SMBus............................................................................................ 149
14.4.1.SMBus Configuration Register............................................................... 150
14.4.2.SMB0CN Control Register ..................................................................... 153
14.4.3.Data Register ......................................................................................... 156
14.5.SMBus Transfer Modes.................................................................................. 157
14.5.1.Master Transmitter Mode ....................................................................... 157
14.5.2.Master Receiver Mode ........................................................................... 158
14.5.3.Slave Receiver Mode ............................................................................. 159
14.5.4.Slave Transmitter Mode ......................................................................... 160
14.6.SMBus Status Decoding................................................................................. 161
15. UART0.................................................................................................................... 163
15.1.Enhanced Baud Rate Generation................................................................... 164
15.2.Operational Modes ......................................................................................... 165
15.2.1.8-Bit UART ............................................................................................. 165
15.2.2.9-Bit UART ............................................................................................. 166
15.3.Multiprocessor Communications .................................................................... 167
16. Enhanced Serial Peripheral Interface (SPI0)...................................................... 173
16.1.Signal Descriptions......................................................................................... 174
16.1.1.Master Out, Slave In (MOSI).................................................................. 174
16.1.2.Master In, Slave Out (MISO).................................................................. 174
16.1.3.Serial Clock (SCK) ................................................................................. 174
16.1.4.Slave Select (NSS) ................................................................................ 174
16.2.SPI0 Master Mode Operation ......................................................................... 175
16.3.SPI0 Slave Mode Operation ........................................................................... 177
16.4.SPI0 Interrupt Sources ................................................................................... 177
16.5.Serial Clock Timing......................................................................................... 178
16.6.SPI Special Function Registers ...................................................................... 180
17. Timers ................................................................................................................... 187
17.1.Timer 0 and Timer 1 ....................................................................................... 187
17.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 187
17.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 189
17.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 189
17.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 190
17.2.Timer 2 .......................................................................................................... 195
17.2.1.16-bit Timer with Auto-Reload................................................................ 195
17.2.2.8-bit Timers with Auto-Reload................................................................ 196
17.3.Timer 3 .......................................................................................................... 199
17.3.1.16-bit Timer with Auto-Reload................................................................ 199
17.3.2.8-bit Timers with Auto-Reload................................................................ 200
18. Programmable Counter Array ............................................................................ 203
18.1.PCA Counter/Timer ........................................................................................ 204
18.2.Capture/Compare Modules ............................................................................ 205
18.2.1.Edge-triggered Capture Mode................................................................ 206
18.2.2.Software Timer (Compare) Mode........................................................... 207
Rev. 1.8
5
C8051F310/1/2/3/4/5/6/7
18.2.3.High-Speed Output Mode ...................................................................... 208
18.2.4.Frequency Output Mode ........................................................................ 209
18.2.5.8-Bit Pulse Width Modulator Mode......................................................... 210
18.2.6.16-Bit Pulse Width Modulator Mode....................................................... 211
18.3.Watchdog Timer Mode ................................................................................... 212
18.3.1.Watchdog Timer Operation .................................................................... 212
18.3.2.Watchdog Timer Usage ......................................................................... 213
18.4.Register Descriptions for PCA........................................................................ 215
19. Revision Specific Behavior ................................................................................. 221
19.1.Revision Identification..................................................................................... 221
19.2.Reset Behavior ............................................................................................... 221
19.2.1.Weak Pullups on GPIO Pins .................................................................. 221
19.2.2.VDD Monitor and the RST Pin ............................................................... 221
19.3.PCA Counter .................................................................................................. 222
20. C2 Interface ........................................................................................................... 223
20.1.C2 Interface Registers.................................................................................... 223
20.2.C2 Pin Sharing ............................................................................................... 225
Document Change List............................................................................................. 226
Contact Information.................................................................................................. 228
6
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
List of Figures
1. System Overview
Figure 1.1. C8051F310 Block Diagram .................................................................... 19
Figure 1.2. C8051F311 Block Diagram .................................................................... 20
Figure 1.3. C8051F312 Block Diagram .................................................................... 21
Figure 1.4. C8051F313 Block Diagram .................................................................... 22
Figure 1.5. C8051F314 Block Diagram .................................................................... 23
Figure 1.6. C8051F315 Block Diagram .................................................................... 24
Figure 1.7. C8051F316 Block Diagram .................................................................... 25
Figure 1.8. C8051F317 Block Diagram .................................................................... 26
Figure 1.9. Comparison of Peak MCU Execution Speeds ....................................... 27
Figure 1.10. On-Chip Clock and Reset..................................................................... 28
Figure 1.11. On-Board Memory Map........................................................................ 29
Figure 1.12. Development/In-System Debug Diagram............................................. 30
Figure 1.13. Digital Crossbar Diagram ..................................................................... 31
Figure 1.14. PCA Block Diagram.............................................................................. 32
Figure 1.15. 12-Bit ADC Block Diagram ................................................................... 33
Figure 1.16. Comparator0 Block Diagram ................................................................ 34
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. LQFP-32 Pinout Diagram (Top View) .................................................... 41
Figure 4.2. LQFP-32 Package Diagram ................................................................... 42
Figure 4.3. Typical LQFP-32 Landing Diagram........................................................ 43
Figure 4.4. QFN-28 Pinout Diagram (Top View) ...................................................... 44
Figure 4.5. QFN-28 Package Drawing ..................................................................... 45
Figure 4.6. Typical QFN-28 Landing Diagram.......................................................... 46
Figure 4.7. QFN-24 Pinout Diagram (Top View) ...................................................... 47
Figure 4.8. QFN-24 Package Drawing ..................................................................... 48
Figure 4.9. Typical QFN-24 Landing Diagram.......................................................... 49
Figure 4.10. QFN-24 Solder Paste Recommendation.............................................. 50
5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only)
Figure 5.1. ADC0 Functional Block Diagram............................................................ 51
Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 52
Figure 5.3. Temperature Sensor Error with 1-Point Calibration ............................... 53
Figure 5.4. 12-Bit ADC Track and Conversion Example Timing .............................. 55
Figure 5.5. ADC0 Equivalent Input Circuits.............................................................. 56
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data ... 63
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data ..... 63
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data ....... 64
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data.......... 64
6. Voltage Reference (C8051F310/1/2/3/6 only)
Figure 6.1. Voltage Reference Functional Block Diagram ....................................... 67
Rev. 1.8
7
C8051F310/1/2/3/4/5/6/7
7. Comparators
Figure 7.1. Comparator0 Functional Block Diagram ................................................ 69
Figure 7.2. Comparator1 Functional Block Diagram ................................................ 70
Figure 7.3. Comparator Hysteresis Plot ................................................................... 71
8. CIP-51 Microcontroller
Figure 8.1. CIP-51 Block Diagram............................................................................ 79
Figure 8.2. Memory Map .......................................................................................... 85
9. Reset Sources
Figure 9.1. Reset Sources...................................................................................... 105
Figure 9.2. Power-On and VDD Monitor Reset Timing .......................................... 106
10. Flash Memory
Figure 10.1. Flash Program Memory Map.............................................................. 113
11. External RAM
12. Oscillators
Figure 12.1. Oscillator Diagram.............................................................................. 121
Figure 12.2. 32.768 kHz External Crystal Example................................................ 126
13. Port Input/Output
Figure 13.1. Port I/O Functional Block Diagram ..................................................... 129
Figure 13.2. Port I/O Cell Block Diagram ............................................................... 130
Figure 13.3. Crossbar Priority Decoder with No Pins Skipped ............................... 131
Figure 13.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 132
14. SMBus
Figure 14.1. SMBus Block Diagram ....................................................................... 145
Figure 14.2. Typical SMBus Configuration ............................................................. 146
Figure 14.3. SMBus Transaction ............................................................................ 147
Figure 14.4. Typical SMBus SCL Generation......................................................... 151
Figure 14.5. Typical Master Transmitter Sequence................................................ 157
Figure 14.6. Typical Master Receiver Sequence.................................................... 158
Figure 14.7. Typical Slave Receiver Sequence...................................................... 159
Figure 14.8. Typical Slave Transmitter Sequence.................................................. 160
15. UART0
Figure 15.1. UART0 Block Diagram ....................................................................... 163
Figure 15.2. UART0 Baud Rate Logic .................................................................... 164
Figure 15.3. UART Interconnect Diagram .............................................................. 165
Figure 15.4. 8-Bit UART Timing Diagram............................................................... 165
Figure 15.5. 9-Bit UART Timing Diagram............................................................... 166
Figure 15.6. UART Multi-Processor Mode Interconnect Diagram .......................... 167
16. Enhanced Serial Peripheral Interface (SPI0)
Figure 16.1. SPI Block Diagram ............................................................................. 173
Figure 16.2. Multiple-Master Mode Connection Diagram ....................................... 176
Figure 16.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 176
Figure 16.4. 4-Wire Single Master and Slave Mode Connection Diagram ............. 176
Figure 16.5. Master Mode Data/Clock Timing ........................................................ 178
Figure 16.6. Slave Mode Data/Clock Timing (CKPHA = 0) .................................... 179
Figure 16.7. Slave Mode Data/Clock Timing (CKPHA = 1) .................................... 179
8
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Figure 16.8. SPI Master Timing (CKPHA = 0)........................................................ 183
Figure 16.9. SPI Master Timing (CKPHA = 1)........................................................ 183
Figure 16.10. SPI Slave Timing (CKPHA = 0)........................................................ 184
Figure 16.11. SPI Slave Timing (CKPHA = 1)........................................................ 184
17. Timers
Figure 17.1. T0 Mode 0 Block Diagram.................................................................. 188
Figure 17.2. T0 Mode 2 Block Diagram.................................................................. 189
Figure 17.3. T0 Mode 3 Block Diagram.................................................................. 190
Figure 17.4. Timer 2 16-Bit Mode Block Diagram .................................................. 195
Figure 17.5. Timer 2 8-Bit Mode Block Diagram .................................................... 196
Figure 17.6. Timer 3 16-Bit Mode Block Diagram .................................................. 199
Figure 17.7. Timer 3 8-Bit Mode Block Diagram .................................................... 200
18. Programmable Counter Array
Figure 18.1. PCA Block Diagram............................................................................ 203
Figure 18.2. PCA Counter/Timer Block Diagram.................................................... 204
Figure 18.3. PCA Interrupt Block Diagram ............................................................. 205
Figure 18.4. PCA Capture Mode Diagram.............................................................. 206
Figure 18.5. PCA Software Timer Mode Diagram .................................................. 207
Figure 18.6. PCA High Speed Output Mode Diagram............................................ 208
Figure 18.7. PCA Frequency Output Mode ............................................................ 209
Figure 18.8. PCA 8-Bit PWM Mode Diagram ......................................................... 210
Figure 18.9. PCA 16-Bit PWM Mode...................................................................... 211
Figure 18.10. PCA Module 4 with Watchdog Timer Enabled ................................. 212
19. Revision Specific Behavior
Figure 19.1. Reading Package Marking ................................................................. 221
20. C2 Interface
Figure 20.1. Typical C2 Pin Sharing....................................................................... 225
Rev. 1.8
9
C8051F310/1/2/3/4/5/6/7
NOTES:
10
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 18
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings* .................................................................. 35
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics ....................................................... 36
Table 3.2. Electrical Characteristics Quick Reference ............................................ 38
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F31x .......................................................... 39
Table 4.2. LQFP-32 Package Dimensions .............................................................. 42
Table 4.3. LQFP-32 Landing Pattern Dimensions ................................................... 43
Table 4.4. QFN-28 Package Dimensions ................................................................ 45
Table 4.5. QFN-28 Landing Pattern Dimensions ..................................................... 46
Table 4.6. QFN-24 Package Dimensions ................................................................ 48
5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only)
Table 5.1. ADC0 Electrical Characteristics .............................................................. 65
6. Voltage Reference (C8051F310/1/2/3/6 only)
Table 6.1. External Voltage Reference Circuit Electrical Characteristics ................ 68
7. Comparators
Table 7.1. Comparator Electrical Characteristics .................................................... 78
8. CIP-51 Microcontroller
Table 8.1. CIP-51 Instruction Set Summary ............................................................ 81
Table 8.2. Special Function Register (SFR) Memory Map ...................................... 87
Table 8.3. Special Function Registers ..................................................................... 88
Table 8.4. Interrupt Summary .................................................................................. 96
9. Reset Sources
Table 9.1. Reset Electrical Characteristics ............................................................ 110
10. Flash Memory
Table 10.1. Flash Electrical Characteristics .......................................................... 112
Table 10.2. Flash Security Summary .................................................................... 114
11. External RAM
12. Oscillators
Table 12.1. Internal Oscillator Electrical Characteristics ....................................... 123
13. Port Input/Output
Table 13.1. Port I/O DC Electrical Characteristics ................................................ 143
14. SMBus
Table 14.1. SMBus Clock Source Selection .......................................................... 150
Table 14.2. Minimum SDA Setup and Hold Times ................................................ 151
Rev. 1.8
11
C8051F310/1/2/3/4/5/6/7
Table 14.3. Sources for Hardware Changes to SMB0CN ..................................... 155
Table 14.4. SMBus Status Decoding ..................................................................... 161
15. UART0
Table 15.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator ............................................................... 170
Table 15.2. Timer Settings for Standard Baud Rates
Using an External 25 MHz Oscillator .................................................. 170
Table 15.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator ......................................... 171
Table 15.4. Timer Settings for Standard Baud Rates
Using an External 18.432 MHz Oscillator ........................................... 171
Table 15.5. Timer Settings for Standard Baud Rates
Using an External 11.0592 MHz Oscillator ......................................... 172
Table 15.6. Timer Settings for Standard Baud Rates
Using an External 3.6864 MHz Oscillator ........................................... 172
16. Enhanced Serial Peripheral Interface (SPI0)
Table 16.1. SPI Slave Timing Parameters ............................................................ 185
17. Timers
18. Programmable Counter Array
Table 18.1. PCA Timebase Input Options ............................................................. 204
Table 18.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 205
Table 18.3. Watchdog Timer Timeout Intervals1 .................................................................. 214
19. Revision Specific Behavior
20. C2 Interface
12
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
List of Registers
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select . . . . . . . . . . . . . . . . . . . 57
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select . . . . . . . . . . . . . . . . . . 58
SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 59
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
SFR Definition 5.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 61
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 61
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 62
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 62
SFR Definition 6.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
SFR Definition 7.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 74
SFR Definition 7.4. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 76
SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 77
SFR Definition 8.1. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
SFR Definition 8.2. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
SFR Definition 8.3. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
SFR Definition 8.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 8.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 8.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 8.7. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
SFR Definition 8.8. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 8.9. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 8.10. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . 100
SFR Definition 8.11. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . 101
SFR Definition 8.12. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
SFR Definition 9.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 9.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 10.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 10.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
SFR Definition 10.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
SFR Definition 11.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 119
SFR Definition 12.1. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 122
SFR Definition 12.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 122
SFR Definition 12.3. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
SFR Definition 12.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 125
SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 134
SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 135
SFR Definition 13.3. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
SFR Definition 13.4. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Rev. 1.8
13
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 13.6. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 13.7. P1: Port1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 13.8. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 13.9. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 139
SFR Definition 13.10. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
SFR Definition 13.11. P2: Port2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
SFR Definition 13.12. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
SFR Definition 13.13. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 141
SFR Definition 13.14. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
SFR Definition 13.15. P3: Port3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 13.16. P3MDIN: Port3 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 13.17. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 152
SFR Definition 14.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 14.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 15.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 168
SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 169
SFR Definition 16.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 180
SFR Definition 16.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
SFR Definition 16.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
SFR Definition 16.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
SFR Definition 17.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
SFR Definition 17.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
SFR Definition 17.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
SFR Definition 17.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
SFR Definition 17.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 198
SFR Definition 17.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 198
SFR Definition 17.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
SFR Definition 17.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
SFR Definition 17.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
SFR Definition 17.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 202
SFR Definition 17.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 202
SFR Definition 17.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 17.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 18.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
SFR Definition 18.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
SFR Definition 18.3. PCA0CPMn: PCA Capture/Compare Mode Registers . . . . . . . 217
SFR Definition 18.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 218
SFR Definition 18.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 218
SFR Definition 18.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 218
14
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 18.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 219
C2 Register Definition 20.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
C2 Register Definition 20.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 223
C2 Register Definition 20.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 224
C2 Register Definition 20.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 224
C2 Register Definition 20.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 224
Rev. 1.8
15
C8051F310/1/2/3/4/5/6/7
NOTES:
16
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
1.
System Overview
C8051F31x devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are
listed below. Refer to Table 1.1 for specific product feature selection.
•
•
•
•
•
•
•
•
•
•
•
•
High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
True 12-bit 200 ksps 25-channel single-ended/differential ADC with analog multiplexer
(C8051F310/1/2/3/6)
Precision programmable 25 MHz internal oscillator
16k kB (C8051F310/1/6/7) or 8 kB (C8051F312/3/4/5) of on-chip Flash memory
1280 bytes of on-chip RAM
SMBus/I2C, Enhanced UART, and Enhanced SPI serial interfaces implemented in hardware
Four general-purpose 16-bit timers
Programmable Counter/Timer Array (PCA) with five capture/compare modules and Watchdog Timer
function
On-chip Power-On Reset, VDD Monitor, and Temperature Sensor
On-chip Voltage Comparators (2)
29/25/21 Port I/O (5 V tolerant)
With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F31x devices
are truly stand-alone System-on-a-Chip solutions. The Flash memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually shut down any or all peripherals for
power savings.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in the final application. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system programming
and debugging without occupying package pins.
Each device is specified for 2.7-to-3.6 V operation over the industrial temperature range (–45 to +85 °C).
The Port I/O and RST pins are tolerant of input signals up to 5 V. The C8051F31x are available in 32-pin
LQFP, 28-pin QFN, and 24-pin QFN packages. See Table 1.1 for ordering part numbers. Note: QFN packages are also referred to as MLP or MLF packages.
Rev. 1.8
17
C8051F310/1/2/3/4/5/6/7
Flash Memory
RAM
Calibrated Internal 24.5 MHz Oscillator
SMBus/I2C
Enhanced SPI
UART
Timers (16-bit)
Programmable Counter Array
Digital Port I/Os
10-bit 200 ksps ADC
Temperature Sensor
Analog Comparators
Lead-free (RoHS Compliant)
Package
C8051F310
25
16
1280
29
2
-
LQFP-32
C8051F310-GQ
25
16
1280
29
2
LQFP-32
C8051F311
25
16
1280
25
2
-
QFN-28
C8051F311-GM
25
16
1280
25
2
QFN-28
C8051F312
25
8
1280
29
2
-
LQFP-32
C8051F312-GQ
25
8
1280
29
2
LQFP-32
C8051F313
25
8
1280
25
2
-
QFN-28
C8051F313-GM
25
8
1280
25
2
QFN-28
C8051F314
25
8
1280
29
-
-
2
-
LQFP-32
C8051F314-GQ
25
8
1280
29
-
-
2
LQFP-32
C8051F315
25
8
1280
25
-
-
2
-
QFN-28
C8051F315-GM
25
8
1280
25
-
-
2
QFN-28
C8051F316-GM
25
16
1280
21
2
QFN-24
C8051F317-GM
25
16
1280
21
-
-
2
QFN-24
Ordering Part Number
MIPS (Peak)
Table 1.1. Product Selection Guide
18
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
16kbyte
FLASH
256 byte
SRAM
PCA/
WDT
1K byte
SRAM
System Clock
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
SMBus
C
o
SFR Bus
r
e
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
VDD
D
r
v
CP0
+
-
CP1
+
-
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
P3.1
P3.2
P3.3
P3.4
VREF
Temp
10-bit
200ksps
ADC
A
M
U
X
AIN0-AIN20
VDD
Figure 1.1. C8051F310 Block Diagram
Rev. 1.8
19
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
16kbyte
FLASH
256 byte
SRAM
1K byte
SRAM
System Clock
C
o
SFR Bus
r
e
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
PCA/
WDT
SMBus
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
VDD
D
r
v
CP0
+
-
CP1
+
-
VREF
Temp
10-bit
200ksps
ADC
A
M
U
X
VDD
Figure 1.2. C8051F311 Block Diagram
20
Rev. 1.8
AIN0-AIN20
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
8 kB
FLASH
256 byte
SRAM
PCA/
WDT
1K byte
SRAM
System Clock
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
SMBus
C
o
SFR Bus
r
e
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
VDD
D
r
v
CP0
+
-
CP1
+
-
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
P3.1
P3.2
P3.3
P3.4
VREF
Temp
10-bit
200ksps
ADC
A
M
U
X
AIN0-AIN20
VDD
Figure 1.3. C8051F312 Block Diagram
Rev. 1.8
21
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
8 kB
FLASH
256 byte
SRAM
1K byte
SRAM
System Clock
C
o
SFR Bus
r
e
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
PCA/
WDT
SMBus
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
VDD
D
r
v
CP0
+
-
CP1
+
-
VREF
Temp
10-bit
200ksps
ADC
A
M
U
X
VDD
Figure 1.4. C8051F313 Block Diagram
22
Rev. 1.8
AIN0-AIN20
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
8 kB
FLASH
256 byte
SRAM
1K byte
SRAM
System Clock
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
PCA/
WDT
SMBus
C
o
SFR Bus
r
e
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
D
r
v
CP0
+
-
CP1
+
-
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
P3.1
P3.2
P3.3
P3.4
Figure 1.5. C8051F314 Block Diagram
Rev. 1.8
23
C8051F310/1/2/3/4/5/6/7
VDD
Analog/Digital
Power
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
8 kB
FLASH
256 byte
SRAM
1K byte
SRAM
System Clock
C
o
SFR Bus
r
e
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
PCA/
WDT
SMBus
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
Figure 1.6. C8051F315 Block Diagram
24
P
1
Rev. 1.8
D
r
v
CP0
+
-
CP1
+
-
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
C8051F310/1/2/3/4/5/6/7
Analog/Digital
Power
VDD
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
16 kB
FLASH
256 byte
SRAM
PCA/
WDT
1 kB
SRAM
System Clock
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
SMBus
C
o
SFR Bus
r
e
P
1
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
VDD
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P3.0/C2D
D
r
v
CP0
+
-
CP1
+
-
VREF
Temp
10-bit
200 ksps
ADC
A
M
U
X
AIN0–AIN20
VDD
Figure 1.7. C8051F316 Block Diagram
Rev. 1.8
25
C8051F310/1/2/3/4/5/6/7
Analog/Digital
Power
VDD
Port 0
Latch
P
0
Port 1
Latch
D
r
v
GND
UART
C2D
Debug HW
Reset
/RST/C2CK
POR
XTAL1
XTAL2
External
Oscillator
Circuit
2%
Internal
Oscillator
BrownOut
8
0
5
1
16 kB
FLASH
256 byte
SRAM
1 kB
SRAM
System Clock
C
o
SFR Bus
r
e
C
R
O
S
S
B
A
R
Timer
0,1,2,3 /
RTC
PCA/
WDT
SMBus
D
r
v
P
2
SPI
D
r
v
Port 2
Latch
P
3
Port 3
Latch
Figure 1.8. C8051F317 Block Diagram
26
P
1
Rev. 1.8
D
r
v
CP0
+
-
CP1
+
-
P0.0/VREF
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P3.0/C2D
C8051F310/1/2/3/4/5/6/7
1.1.
CIP-51™ Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051F31x family utilizes Silicon Laboratories' proprietary CIP-51 microcontroller core. The CIP-51 is
fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be
used to develop software. The CIP-51 core offers all the peripherals included with a standard 8052, including four 16-bit counter/timers, a full-duplex UART with extended baud rate configuration, an enhanced SPI
port, 1280 bytes of internal RAM, 128 byte Special Function Register (SFR) address space, and 29/25/21
I/O pins.
1.1.2. Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than
four system clock cycles.
The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that
require each execution time.
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Number of Instructions
26
50
5
14
7
3
1
2
1
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. Figure 1.9
shows a comparison of peak throughputs for various 8-bit microcontroller cores with their maximum system clocks.
25
MIPS
20
15
10
5
Silicon Labs
Microchip
Philips
ADuC812
CIP-51
PIC17C75x
80C51
8051
(25 MHz clk) (33 MHz clk) (33 MHz clk) (16 MHz clk)
Figure 1.9. Comparison of Peak MCU Execution Speeds
Rev. 1.8
27
C8051F310/1/2/3/4/5/6/7
1.1.3. Additional Features
The C8051F31x SoC family includes several key enhancements to the CIP-51 core and peripherals to
improve performance and ease of use in end applications.
The extended interrupt handler provides 14 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), allowing numerous analog and digital peripherals to interrupt the controller. An interrupt driven
system requires less intervention by the MCU, giving it more effective throughput. The extra interrupt
sources are very useful when building multi-tasking, real-time systems.
Eight reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor (forces reset
when power supply voltage drops below VRST as given in Table 9.1 on page 110), a Watchdog Timer, a
Missing Clock Detector, a voltage level detection from Comparator0, a forced software reset, an external
reset pin, and an errant Flash read/write protection circuit. Each reset source except for the POR, Reset
Input Pin, or Flash error may be disabled by the user in software. The WDT may be permanently enabled
in software after a power-on reset during MCU initialization.
The internal oscillator is factory calibrated to 24.5 MHz ±2%. An external oscillator drive circuit is also
included, allowing an external crystal, ceramic resonator, capacitor, RC, or CMOS clock source to generate
the system clock. If desired, the system clock source may be switched on-the-fly between the internal and
external oscillator circuits. An external oscillator can be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switching to the
fast internal oscillator as needed.
VDD
Power On
Reset
Supply
Monitor
Px.x
Px.x
+
-
Comparator 0
'0'
Enable
(wired-OR)
+
C0RSEF
Missing
Clock
Detector
(oneshot)
EN
Reset
Funnel
PCA
WDT
(Software Reset)
SWRSF
Errant
FLASH
Operation
Internal
Oscillator
XTAL1
XTAL2
External
Oscillator
Drive
System
Clock
Clock Select
WDT
Enable
MCD
Enable
EN
CIP-51
Microcontroller
Core
System Reset
Extended Interrupt
Handler
Figure 1.10. On-Chip Clock and Reset
28
Rev. 1.8
/RST
C8051F310/1/2/3/4/5/6/7
1.2.
On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data
RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
Program memory consists of 8 or 16k kB of Flash. This memory may be reprogrammed in-system in 512
byte sectors, and requires no special off-chip programming voltage. See Figure 1.11 for the MCU system
memory map.
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(Flash)
C8051F310/1/6/7
0x3E00
0x3DFF
0xFF
RESERVED
0x80
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
16 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x30
0x2F
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0x0000
0xFFFF
C8051F312/3/4/5
0x2000
0x1FFF
RESERVED
Same 1024 bytes as from
0x0000 to 0x03FF, wrapped
on 1 kB boundaries
8 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x0400
0x03FF
0x0000
XRAM - 1024 Bytes
(accessable using MOVX
instruction)
0x0000
Figure 1.11. On-Board Memory Map
Rev. 1.8
29
C8051F310/1/2/3/4/5/6/7
1.3.
On-Chip Debug Circuitry
The C8051F31x devices include on-chip Silicon Labs 2-Wire (C2) debug circuitry that provides non-intrusive, full speed, in-circuit debugging of the production part installed in the end application.
Silicon Labs' debugging system supports inspection and modification of memory and registers, breakpoints, and single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging.
All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single
stepping, or at a breakpoint in order to keep them synchronized.
The C8051F310DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F31x MCUs. The kit includes software with a
developer's studio and debugger, an integrated 8051 assembler, a debug adapter, a target application
board with the associated MCU installed, and the required cables and wall-mount power supply.
The Silicon Labs IDE interface is a vastly superior developing and debugging configuration, compared to
standard MCU emulators that use on-board "ICE Chips" and require the MCU in the application board to
be socketed. Silicon Labs' debug paradigm increases ease of use and preserves the performance of the
precision analog peripherals.
Silicon Laboratories Integrated
Development Environment
Windows 98SE or later
Debug
Adapter
C2 (x2), VDD, GND
VDD
TARGET PCB
GND
C8051F31x
Figure 1.12. Development/In-System Debug Diagram
30
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
1.4.
Programmable Digital I/O and Crossbar
C8051F310/2/4 devices include 29 I/O pins (three byte-wide Ports and one 5-bit-wide Port);
C8051F311/3/5 devices include 25 I/O pins (three byte-wide Ports and one 1-bit-wide Port); C8051F316/7
devices include 21 I/O pins (one byte-wide Port, two 6-bit-wide Ports and one 1-bit-wide Port). The
C8051F31x Ports behave like typical 8051 Ports with a few enhancements. Each Port pin may be configured as an analog input or a digital I/O pin. Pins selected as digital I/Os may additionally be configured for
push-pull or open-drain output. The “weak pullups” that are fixed on typical 8051 devices may be globally
disabled, providing power savings capabilities.
The Digital Crossbar allows mapping of internal digital system resources to Port I/O pins (See Figure 1.13).
On-chip counter/timers, serial buses, HW interrupts, comparator output, and other digital signals in the
controller can be configured to appear on the Port I/O pins specified in the Crossbar Control registers. This
allows the user to select the exact mix of general purpose Port I/O and digital resources needed for the
particular application.
XBR0, XBR1,
PnSKIP Registers
PnMDOUT,
PnMDIN Registers
Priority
Decoder
Highest
Priority
UART
4
SPI
(Internal Digital Signals)
2
SMBus
8
P0
I/O
Cells
P0.0
P1
I/O
Cells
P1.0
P2
I/O
Cells
P2.0
CP0
Outputs
2
CP1
Outputs
2
Digital
Crossbar
8
4
8
SYSCLK
P3
I/O
Cells
P3.0
4
P1.7
P2.7
6
PCA
5
Lowest
Priority
P0.7
2
T0, T1
2
P3.4
8
P0
(P0.0-P0.7)
P1
(P1.0-P1.7)
Notes:
1. P3.1–P3.4 only available on the
C8051F310/2/4.
2. P1.6, P1.7, P2.6, P2.7 only
available on the C8051F310/1/2/3/4/5
(Port Latches)
8
4
(P2.0-P2.3)
P2
4
(P2.4-P2.7)
5
P3
(P3.0-P3.4)
Figure 1.13. Digital Crossbar Diagram
Rev. 1.8
31
C8051F310/1/2/3/4/5/6/7
1.5.
Serial Ports
The C8051F31x Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud rate
configuration, and an Enhanced SPI interface. Each of the serial buses is fully implemented in hardware
and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention.
1.6.
Programmable Counter Array
An on-chip Programmable Counter/Timer Array (PCA) is included in addition to the four 16-bit general purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with five programmable capture/compare modules. The PCA clock is derived from one of six sources: the system clock divided
by 12, the system clock divided by 4, Timer 0 overflows, an External Clock Input (ECI), the system clock, or
the external oscillator clock source divided by 8. The external clock source selection is useful for real-time
clock functionality, where the PCA is clocked by an external source while the internal oscillator drives the
system clock.
Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture,
Software Timer, High Speed Output, 8- or 16-bit Pulse Width Modulator, or Frequency Output. Additionally,
Capture/Compare Module 4 offers watchdog timer (WDT) capabilities. Following a system reset, Module 4
is configured and enabled in WDT mode. The PCA Capture/Compare Module I/O and External Clock Input
may be routed to Port I/O via the Digital Crossbar.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
PCA
CLOCK
MUX
16-Bit Counter/Timer
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Capture/Compare
Module 3
Figure 1.14. PCA Block Diagram
32
Rev. 1.8
CEX4
Port I/O
CEX3
CEX2
CEX1
CEX0
ECI
Crossbar
Capture/Compare
Module 4 / WDT
C8051F310/1/2/3/4/5/6/7
1.7.
12-Bit Analog to Digital Converter
The C8051F310/1/2/3/6 devices include an on-chip 12-bit SAR ADC with a 25-channel differential input
multiplexer. With a maximum throughput of 200 ksps, the ADC offers true 12-bit accuracy with an INL of
±1LSB. The ADC system includes a configurable analog multiplexer that selects both positive and negative ADC inputs. Ports1-3 are available as an ADC inputs; additionally, the on-chip Temperature Sensor
output and the power supply voltage (VDD) are available as ADC inputs. User firmware may shut down the
ADC to save power.
Conversions can be started in six ways: a software command, an overflow of Timer 0, 1, 2, or 3, or an
external convert start signal. This flexibility allows the start of conversion to be triggered by software
events, a periodic signal (timer overflows), or external HW signals. Conversion completions are indicated
by a status bit and an interrupt (if enabled). The resulting 12-bit data word is latched into the ADC data
SFRs upon completion of a conversion.
Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is
either within or outside of a specified range. The ADC can monitor a key voltage continuously in background mode, but not interrupt the controller unless the converted data is within/outside the specified
range.
Analog Multiplexer
P1.0
P1.6, P1.7 available on
C8051F310/1/2/3/4/5
P2.6, P2.7 available on
C8051F310/1/2/3/4/5
P3.1-3.4
available on
C8051F310/2
Configuration, Control, and Data Registers
P1.7
P2.0
23-to-1
AMUX
Start
Conversion
P2.7
P3.0
P3.4
000
AD0BUSY (W)
001
Timer 0 Overflow
010
Timer 2 Overflow
011
Timer 1 Overflow
100
CNVSTR Input
101
Timer 3 Overflow
VDD
Temp
Sensor
(+)
(-)
P1.0
P1.6, P1.7 available on
C8051F310/1/2/3/4/5
P2.6, P2.7 available on
C8051F310/1/2/3/4/5
P3.1-3.4
available on
C8051F310/2
10-Bit
SAR
ADC
P1.7
P2.0
End of
Conversion
Interrupt
23-to-1
AMUX
16
ADC Data
Registers
Window Compare
Logic
Window
Compare
Interrupt
P2.7
P3.0
P3.4
VREF
GND
Figure 1.15. 12-Bit ADC Block Diagram
Rev. 1.8
33
C8051F310/1/2/3/4/5/6/7
1.8.
Comparators
C8051F31x devices include two on-chip voltage comparators that are enabled/disabled and configured via
user software. Port I/O pins may be configured as comparator inputs via a selection mux. Two comparator
outputs may be routed to a Port pin if desired: a latched output and/or an unlatched (asynchronous) output.
Comparator response time is programmable, allowing the user to select between high-speed and lowpower modes. Positive and negative hysteresis are also configurable.
Comparator interrupts may be generated on rising, falling, or both edges. When in IDLE mode, these interrupts may be used as a “wake-up” source. Comparator0 may also be configured as a reset source.
Figure 1.16 shows he Comparator0 block diagram.
CP0EN
CPT0CN
CPT0MX
CP0OUT
CMX0N1
CMX0N0
CP0RIF
VDD
CP0FIF
CP0HYP1
CP0HYP0
CP0
Interrupt
CP0HYN1
CP0HYN0
CMX0P1
CMX0P0
CP0
Rising-edge
P1.0
CP0
Falling-edge
P1.4
P2.0
CP0 +
Interrupt
Logic
P2.4
CP0
+
D
-
CLR
Q
Q
D
SET
CLR
Q
Q
Crossbar
P1.1
P1.5
SET
(SYNCHRONIZER)
GND
CP0 -
P2.1
CP0A
Reset
Decision
Tree
CPT0MD
P2.5
CP0RIE
CP0FIE
CP0MD1
CP0MD0
Figure 1.16. Comparator0 Block Diagram
34
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
2.
Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter
Conditions
Min
Typ
Max
Units
Ambient temperature under bias
–55
—
125
°C
Storage Temperature
–65
—
150
°C
Voltage on any Port I/O Pin or RST with
respect to GND
–0.3
—
5.8
V
Voltage on VDD with respect to GND
–0.3
—
4.2
V
Maximum Total current through VDD and
GND
—
—
500
mA
Maximum output current sunk by RST or any
Port pin
—
—
100
mA
*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to
the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
Rev. 1.8
35
C8051F310/1/2/3/4/5/6/7
3.
Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40°C to +85°C, 25 MHz System Clock unless otherwise specified.
Parameter
Conditions
Typ
Max
Units
3.0
3.6
V
—
1.5
—
V
–40
—
+85
°C
SYSCLK (system clock frequency)
02
—
25
MHz
Tsysl (SYSCLK low time)
18
—
—
ns
Tsysh (SYSCLK high time)
18
—
—
ns
Digital Supply Voltage
Min
VRST
Digital Supply RAM Data Retention
Voltage
Specified Operating Temperature
Range
1
Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash)
IDD (Note 3)
IDD Supply Sensitivity (Note 3,
Note 4)
VDD = 3.0 V, F = 25 MHz
—
7.8
8.6
mA
VDD = 3.0 V, F = 1 MHz
—
0.38
—
mA
VDD = 3.0 V, F = 80 kHz
—
31
—
µA
VDD = 3.6 V, F = 25 MHz
—
10.7
12.1
mA
F = 25 MHz
—
67
—
%/V
F = 1 MHz
—
62
—
%/V
IDD Frequency Sensitivity (Note 3, VDD = 3.0 V, F < 15 MHz, T = 25 ºC
Note 5)
VDD = 3.0 V, F > 15 MHz, T = 25 ºC
—
0.39
—
mA/MHz
—
0.21
—
mA/MHz
VDD = 3.6 V, F < 15 MHz, T = 25 ºC
—
0.55
—
mA/MHz
VDD = 3.6 V, F > 15 MHz, T = 25 ºC
—
0.27
—
mA/MHz
Notes:
1.
2.
3.
4.
Given in Table 9.1 on page 110.
SYSCLK must be at least 32 kHz to enable debugging.
Based on device characterization data, not production tested.
Active and Inactive IDD at voltages and frequencies other than those specified can be calculated
using the IDD Supply Sensitivity. For example, if the VDD is 3.3 V instead of 3.0 V at 25 MHz: IDD =
7.8 mA typical at 3.0 V and f = 25 MHz. From this, IDD = 7.8 mA + 0.67 x (3.3 V – 3.0 V) = 8 mA at
3.3 V and f = 25 MHz.
5. IDD can be estimated for frequencies < 15 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate IDD for > 15 MHz,
the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:
VDD = 3.0 V; F = 20 MHz, IDD = 7.8 mA – (25 MHz – 20 MHz) x 0.21 mA/MHz = 6.75 mA.
6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the
frequency sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1
MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the
frequency sensitivity number. For example:
VDD = 3.0 V; F = 5 MHz, Idle IDD = 4.8 mA – (25 MHz – 5 MHz) x 0.15 mA/MHz = 1.8 mA.
36
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Table 3.1. Global DC Electrical Characteristics (Continued)
–40°C to +85°C, 25 MHz System Clock unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash)
IDD (Note 3)
IDD Supply Sensitivity (Note 3,
Note 4)
IDD Frequency Sensitivity (Note 3,
Note 6)
Digital Supply Current
(Stop Mode, shutdown)
VDD = 3.0 V, F = 25 MHz
—
3.8
4.3
mA
VDD = 3.0 V, F = 1 MHz
—
0.20
—
mA
VDD = 3.0 V, F = 80 kHz
—
16
—
µA
VDD = 3.6 V, F = 25 MHz
—
4.8
5.3
mA
F = 25 MHz
—
44
—
%/V
F = 1 MHz
—
56
—
%/V
VDD = 3.0 V, F < 1 MHz, T = 25 °C
—
0.21
—
mA/MHz
VDD = 3.0 V, F > 1 MHz, T = 25 °C
—
0.15
—
mA/MHz
VDD = 3.6 V, F < 1 MHz, T = 25 °C
—
0.28
—
mA/MHz
VDD = 3.6 V, F > 1 MHz, T = 25 °C
—
0.19
—
mA/MHz
Oscillator not running,
VDD Monitor Disabled
—
< 0.1
—
µA
Notes:
1.
2.
3.
4.
Given in Table 9.1 on page 110.
SYSCLK must be at least 32 kHz to enable debugging.
Based on device characterization data, not production tested.
Active and Inactive IDD at voltages and frequencies other than those specified can be calculated
using the IDD Supply Sensitivity. For example, if the VDD is 3.3 V instead of 3.0 V at 25 MHz: IDD =
7.8 mA typical at 3.0 V and f = 25 MHz. From this, IDD = 7.8 mA + 0.67 x (3.3 V – 3.0 V) = 8 mA at
3.3 V and f = 25 MHz.
5. IDD can be estimated for frequencies < 15 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate IDD for > 15 MHz,
the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:
VDD = 3.0 V; F = 20 MHz, IDD = 7.8 mA – (25 MHz – 20 MHz) x 0.21 mA/MHz = 6.75 mA.
6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the
frequency sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1
MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the
frequency sensitivity number. For example:
VDD = 3.0 V; F = 5 MHz, Idle IDD = 4.8 mA – (25 MHz – 5 MHz) x 0.15 mA/MHz = 1.8 mA.
Rev. 1.8
37
C8051F310/1/2/3/4/5/6/7
Other electrical characteristics tables are found in the data sheet section corresponding to the associated
peripherals. For more information on electrical characteristics for a specific peripheral, refer to the page
indicated in Table 3.2.
Table 3.2. Electrical Characteristics Quick Reference
Peripheral Electrical Characteristics
Page No.
ADC0 Electrical Characteristics
65
External Voltage Reference Circuit Electrical Characteristics
68
Comparator Electrical Characteristics
78
Reset Electrical Characteristics
110
Flash Electrical Characteristics
112
Internal Oscillator Electrical Characteristics
123
Port I/O DC Electrical Characteristics
143
38
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
4.
Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F31x
Name
Pin Numbers
‘F310/2/4 ‘F311/3/5 ‘F316/7
Type
Description
VDD
4
4
4
Power Supply Voltage.
GND
3
3
3
Ground.
RST/
D I/O
Device Reset. Open-drain output of internal POR. An
external source can initiate a system reset by driving
this pin low for at least 10 µs.
C2CK
D I/O
Clock signal for the C2 Debug Interface.
P3.0/
D I/O
Port 3.0. See Section 13 for a complete description.
D I/O
Bi-directional data signal for the C2 Debug Interface.
D I/O
Port 0.0. See Section 13 for a complete description.
A In
External VREF input. (‘F310/1/2/3 only)
D I/O
Port 0.1. See Section 13 for a complete description.
D I/O
Port 0.2. See Section 13 for a complete description.
XTAL1
A In
External Clock Input. This pin is the external oscillator
return for a crystal or resonator.
P0.3/
D I/O
Port 0.3. See Section 13 for a complete description.
5
6
5
6
5
6
C2D
P0.0/
2
2
2
VREF
P0.1
1
1
1
P0.2/
32
28
24
External Clock Output. For an external crystal or resoA Out or nator, this pin is the excitation driver. This pin is the
D In external clock input for CMOS, capacitor, or RC oscillator configurations.
31
27
23
P0.4
30
26
22
D I/O
Port 0.4. See Section 13 for a complete description.
P0.5
29
25
21
D I/O
Port 0.5. See Section 13 for a complete description.
28
24
20
P0.7
27
23
19
P1.0
26
22
18
D I/O or
Port 1.0. See Section 13 for a complete description.
A In
P1.1
25
21
17
D I/O or
Port 1.1. See Section 13 for a complete description.
A In
P1.2
24
20
16
D I/O or
Port 1.2. See Section 13 for a complete description.
A In
P1.3
23
19
15
D I/O or
Port 1.3. See Section 13 for a complete description.
A In
P1.4
22
18
14
D I/O or
Port 1.4. See Section 13 for a complete description.
A In
XTAL2
P0.6/
Port 0.6. See Section 13 for a complete description.
CNVSTR
ADC0 External Convert Start Input. (‘F310/1/2/3 only)
D I/O
Port 0.7. See Section 13 for a complete description.
Rev. 1.8
39
C8051F310/1/2/3/4/5/6/7
Table 4.1. Pin Definitions for the C8051F31x (Continued)
Name
40
Pin Numbers
‘F310/2/4 ‘F311/3/5 ‘F316/7
13
Type
Description
D I/O or
Port 1.5. See Section 13 for a complete description.
A In
P1.5
21
17
P1.6
20
16
D I/O or
Port 1.6. See Section 13 for a complete description.
A In
P1.7
19
15
D I/O or
Port 1.7. See Section 13 for a complete description.
A In
P2.0
18
14
12
D I/O or
Port 2.0. See Section 13 for a complete description.
A In
P2.1
17
13
11
D I/O or
Port 2.1. See Section 13 for a complete description.
A In
P2.2
16
12
10
D I/O or
Port 2.2. See Section 13 for a complete description.
A In
P2.3
15
11
9
D I/O or
Port 2.3. See Section 13 for a complete description.
A In
P2.4
14
10
8
D I/O or
Port 2.4. See Section 13 for a complete description.
A In
P2.5
13
9
7
D I/O or
Port 2.5. See Section 13 for a complete description.
A In
P2.6
12
8
D I/O or
Port 2.6. See Section 13 for a complete description.
A In
P2.7
11
7
D I/O or
Port 2.7. See Section 13 for a complete description.
A In
P3.1
7
D I/O or
Port 3.1. See Section 13 for a complete description.
A In
P3.2
8
D I/O or
Port 3.2. See Section 13 for a complete description.
A In
P3.3
9
D I/O or
Port 3.3. See Section 13 for a complete description.
A In
P3.4
10
D I/O or
Port 3.4. See Section 13 for a complete description.
A In
Rev. 1.8
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
P1.1
32
31
30
29
28
27
26
25
C8051F310/1/2/3/4/5/6/7
P0.1
1
24
P1.2
P0.0
2
23
P1.3
GND
3
22
P1.4
VDD
4
21
P1.5
/RST/C2CK
5
20
P1.6
P3.0/C2D
6
19
P1.7
P3.1
7
18
P2.0
P3.2
8
17
P2.1
13
14
15
16
P2.5
P2.4
P2.3
P2.2
11
P2.7
12
10
P3.4
P2.6
9
P3.3
C8051F310/2/4
Top View
Figure 4.1. LQFP-32 Pinout Diagram (Top View)
Rev. 1.8
41
C8051F310/1/2/3/4/5/6/7
Table 4.2. LQFP-32
Package Dimensions
D
D1
E1 E
32
PIN 1
IDENTIFIER
A
A1
A2
b
D
D1
e
E
E1
L
1
A2
A
L
b
A1
e
Figure 4.2. LQFP-32 Package Diagram
42
Rev. 1.8
MIN
0.05
1.35
0.30
0.45
MM
TYP
1.40
0.37
9.00
7.00
0.80
9.00
7.00
0.60
MAX
1.60
0.15
1.45
0.45
0.75
C8051F310/1/2/3/4/5/6/7
Figure 4.3. Typical LQFP-32 Landing Diagram
Table 4.3. LQFP-32 Landing Pattern Dimensions
Dimension
Min
Max
C1
C2
E
X1
Y1
8.40
8.40
8.50
8.50
0.80 BSC.
0.40
1.25
0.50
1.35
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60?m minimum, all the way around the pad.
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
5. The stencil thickness should be 0.125mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all pads.
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small Body
Components.
Rev. 1.8
43
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
27
26
25
24
23
22
GND
28
C8051F310/1/2/3/4/5/6/7
P0.1
1
21
P1.1
P0.0
2
20
P1.2
GND
3
19
P1.3
VDD
4
18
P1.4
/RST/C2CK
5
17
P1.5
P3.0/C2D
6
16
P1.6
15
P1.7
C8051F311/3/5
Top View
GND
8
9
10
11
12
13
14
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
7
P2.6
P2.7
Figure 4.4. QFN-28 Pinout Diagram (Top View)
44
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Figure 4.5. QFN-28 Package Drawing
Table 4.4. QFN-28 Package Dimensions
MM
MM
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
A1
A3
b
D
D2
e
E
E2
0.80
0.00
0.90
0.02
0.25 REF
0.23
5.00 BSC.
3.15
0.50 BSC.
5.00 BSC.
3.15
1.00
0.05
L
L1
aaa
bbb
ddd
eee
Z
Y
0.35
0.00
0.55
—
0.15
0.10
0.05
0.08
0.44
0.18
0.65
0.15
0.18
2.90
2.90
0.30
3.35
3.35
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MO-220, variation VHHD except for custom features D2,
E2, L, Z, and Y which are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 1.8
45
C8051F310/1/2/3/4/5/6/7
Figure 4.6. Typical QFN-28 Landing Diagram
Table 4.5. QFN-28 Landing Pattern Dimensions
Dimension
C1
C2
E
X1
X2
Y1
Y2
Min
Max
4.80
4.80
0.50
0.20
3.20
0.85
3.20
0.30
3.30
0.95
3.30
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification.
3. This Land Pattern Design is based on the IPC-7351 guidelines.
4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60?m minimum, all the way around the pad.
5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
6. The stencil thickness should be 0.125mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
8. A 3x3 array of 0.90mm openings on a 1.1mm pitch should be used for the center pad to assure the proper
paste volume.
9. A No-Clean, Type-3 solder paste is recommended.
10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
46
Rev. 1.8
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
24
23
22
21
20
19
C8051F310/1/2/3/4/5/6/7
P0.1
1
18
P1.0
P0.0
2
17
P1.1
GND
3
16
P1.2
VDD
4
15
P1.3
/RST / C2CK
5
14
P1.4
P3.0 / C2D
6
13
P1.5
C8051F316/7
Top View
7
8
9
10
11
12
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
GND
Figure 4.7. QFN-24 Pinout Diagram (Top View)
Rev. 1.8
47
C8051F310/1/2/3/4/5/6/7
Figure 4.8. QFN-24 Package Drawing
Table 4.6. QFN-24 Package Dimensions
MM
MM
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
A1
b
D
D2
e
E
E2
0.70
0.00
0.18
0.75
0.02
0.25
4.00 BSC.
2.70
0.50 BSC.
4.00 BSC.
2.70
0.80
0.05
0.30
L
L1
aaa
bbb
ddd
eee
Z
Y
0.30
0.00
—
—
—
—
0.40
—
—
—
—
—
0.24
0.18
0.50
0.15
0.15
0.10
0.05
0.08
2.55
2.55
2.80
2.80
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation WGGD except for
custom features D2, E2, Z, Y, and L which are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
48
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Figure 4.9. Typical QFN-24 Landing Diagram
Table 4.7. QFN-24 Landing Pattern Dimensions
Dimension
Min
Max
C1
C2
E
X1
X2
Y1
Y2
3.90
3.90
4.00
4.00
0.50 BSC.
0.20
2.70
0.65
2.70
0.30
2.80
0.75
2.80
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This land pattern design is based on the IPC-7351 guidelines.
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60?m minimum, all the way around the pad.
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
5. The stencil thickness should be 0.125mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads.
7. A 2x2 array of 1.10mm x 1.10mm openings on 1.30mm pitch should be used for the center ground pad.
8. A No-Clean, Type-3 solder paste is recommended.
9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 1.8
49
C8051F310/1/2/3/4/5/6/7
50
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
5.
12-Bit ADC (ADC0, C8051F310/1/2/3/6 only)
The ADC0 subsystem for the C8051F310/1/2/3/6 consists of two analog multiplexers (referred to collectively as AMUX0) with 25 total input selections, and a 200 ksps, 12-bit successive-approximation-register
ADC with integrated track-and-hold and programmable window detector. The AMUX0, data conversion
modes, and window detector are all configurable under software control via the Special Function Registers
shown in Figure 5.1. ADC0 operates in both Single-ended and Differential modes, and may be configured
to measure P1.0–P3.4, the Temperature Sensor output, or VDD with respect to P1.0–P3.4, VREF, or GND.
The ADC0 subsystem is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set
to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
P1.0
P2.6-2.7 available on
C8051F310/1/2/3/4/5
P3.1-3.4
available on
C8051F310/2
P3.4
ADC0L
10-Bit
SAR
(+)
ADC0CF
AD0BUSY (W)
001
010
Timer 0 Overflow
Timer 2 Overflow
011
100
Timer 1 Overflow
CNVSTR Input
101
Timer 3 Overflow
REF
SYSCLK
AD0SC0
AD0LJST
AD0SC1
AD0SC2
AD0SC3
AMX0N0
AMX0N1
P3.4
AMX0N2
AMX0N4
P2.7
P3.0
AMX0N
AMX0N3
23-to-1
AMUX
AD0SC4
P1.7
P2.0
000
ADC0H
ADC
(-)
P1.0
P3.1-3.4
available on
C8051F310/2
AD0CM0
Start
Conversion
Temp
Sensor
P2.6-2.7 available on
C8051F310/1/2/3/4/5
AD0CM1
VDD
P2.7
P3.0
VDD
P1.6-1.7 available on
C8051F310/1/2/3/4/5
AD0CM2
AD0WINT
AD0INT
AD0BUSY
AD0EN
23-to-1
AMUX
AD0TM
AMX0P0
ADC0CN
AMX0P1
AMX0P2
P1.7
P2.0
AMX0P3
AMX0P4
AMX0P
P1.6-1.7 available on
C8051F310/1/2/3/4/5
AD0WINT
32
ADC0LTH
ADC0LTL
Window
Compare
Logic
ADC0GTH ADC0GTL
VREF
GND
Figure 5.1. ADC0 Functional Block Diagram
5.1.
Analog Multiplexer
AMUX0 selects the positive and negative inputs to the ADC. Any of the following may be selected as the
positive input: P1.0-P3.4, the on-chip temperature sensor, or the positive power supply (VDD). Any of the
following may be selected as the negative input: P1.0-P3.4, VREF, or GND. When GND is selected as
the negative input, ADC0 operates in Single-ended Mode; all other times, ADC0 operates in Differential Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in
SFR Definition 5.1 and SFR Definition 5.2.
The conversion code format differs between Single-ended and Differential modes. The registers ADC0H
and ADC0L contain the high and low bytes of the output conversion code from the ADC at the completion
of each conversion. Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit
(ADC0CN.0). When in Single-ended Mode, conversion codes are represented as 12-bit unsigned integers.
Rev. 1.8
51
C8051F310/1/2/3/4/5/6/7
Inputs are measured from ‘0’ to VREF * 1023/1024. Example codes are shown below for both right-justified
and left-justified data. Unused bits in the ADC0H and ADC0L registers are set to ‘0’.
Input Voltage
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
0x03FF
0x0200
0x0100
0x0000
VREF x 1023/1024
VREF x 512/1024
VREF x 256/1024
0
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
0xFFC0
0x8000
0x4000
0x0000
When in Differential Mode, conversion codes are represented as 12-bit signed 2’s complement numbers.
Inputs are measured from -VREF to VREF * 511/512. Example codes are shown below for both right-justified and left-justified data. For right-justified data, the unused MSBs of ADC0H are a sign-extension of the
data word. For left-justified data, the unused LSBs in the ADC0L register are set to ‘0’.
Input Voltage
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
0x01FF
0x0100
0x0000
0xFF00
0xFE00
VREF x 511/512
VREF x 256/512
0
–VREF x 256/512
–VREF
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
0x7FC0
0x4000
0x0000
0xC000
0x8000
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be configured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set to ‘0’ the corresponding bit in register PnMDIN (for n = 0,1,2,3). To force the Crossbar to skip a
Port pin, set to ‘1’ the corresponding bit in register PnSKIP (for n = 0,1,2). See Section “13. Port Input/
Output” on page 129 for more Port I/O configuration details.
5.2.
Temperature Sensor
The typical temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the
positive ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P.
(mV)
1200
1100
1000
900
VTEMP = 3.35*(TEMPC) + 897 mV
800
700
-50
0
50
100
(Celsius)
Figure 5.2. Typical Temperature Sensor Transfer Function
52
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature measurements (see Table 5.1 for linearity specifications). For absolute temperature measurements, gain and/
or offset calibration is recommended. Typically a 1-point calibration includes the following steps:
Step 1. Control/measure the ambient temperature (this temperature must be known).
Step 2. Power the device, and delay for a few seconds to allow for self-heating.
Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input
and GND selected as the negative input.
Step 4. Calculate the offset and/or gain characteristics, and store these values in non-volatile
memory for use with subsequent temperature sensor measurements.
Error (degrees C)
Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Note that
parameters which affect ADC measurement, in particular the voltage reference value, will also
affect temperature measurement.
5.00
5.00
4.00
4.00
3.00
3.00
2.00
2.00
1.00
1.00
0.00
-40.00
-20.00
40.00
0.00
60.00
20.00
0.00
80.00
-1.00
-1.00
-2.00
-2.00
-3.00
-3.00
-4.00
-4.00
-5.00
-5.00
Temperature (degrees C)
Figure 5.3. Temperature Sensor Error with 1-Point Calibration
Rev. 1.8
53
C8051F310/1/2/3/4/5/6/7
5.3.
Modes of Operation
ADC0 has a maximum conversion speed of 200 ksps. The ADC0 conversion clock is a divided version of
the system clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by
(AD0SC + 1) for 0 AD0SC 31).
5.3.1. Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM2-0) in register ADC0CN. Conversions may be initiated by one of the following:
1.
2.
3.
4.
5.
6.
Writing a ‘1’ to the AD0BUSY bit of register ADC0CN
A Timer 0 overflow (i.e., timed continuous conversions)
A Timer 2 overflow
A Timer 1 overflow
A rising edge on the CNVSTR input signal (pin P0.6)
A Timer 3 overflow
Writing a ‘1’ to AD0BUSY provides software control of ADC0 whereby conversions are performed "ondemand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is
complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt
flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT)
should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT
is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. See
Section “17. Timers” on page 187 for timer configuration.
Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port pin P0.6. When the
CNVSTR input is used as the ADC0 conversion source, Port pin P0.6 should be skipped by the Digital
Crossbar. To configure the Crossbar to skip P0.6, set to ‘1’ Bit6 in register P0SKIP. See Section “13. Port
Input/Output” on page 129 for details on Port I/O configuration.
54
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
5.3.2. Tracking Modes
According to Table 5.1, each ADC0 conversion must be preceded by a minimum tracking time for the converted result to be accurate. The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode.
In its default state, the ADC0 input is continuously tracked, except when a conversion is in progress. When
the AD0TM bit is logic 1, ADC0 operates in low-power track-and-hold mode. In this mode, each conversion
is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR
signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR is low;
conversion begins on the rising edge of CNVSTR (see Figure 5.4). Tracking can also be disabled (shutdown) when the device is in low power standby or sleep modes. Low-power track-and-hold mode is also
useful when AMUX settings are frequently changed, due to the settling time requirements described in
Section “5.3.3. Settling Time Requirements” on page 56.
A. ADC0 Timing for External Trigger Source
CNVSTR
(AD0CM[2:0]=100)
1
2
3
4
5
6
7
8
9
10 11
SAR Clocks
AD0TM=1
AD0TM=0
Write '1' to AD0BUSY,
Timer 0, Timer 2,
Timer 1, Timer 3 Overflow
(AD0CM[2:0]=000, 001,010
011, 101)
Low Power
or Convert
Track
Track or Convert
Convert
Low Power
Mode
Convert
Track
B. ADC0 Timing for Internal Trigger Source
1
2
3
4
5
6
7
8
9
10 11 12 13 14
SAR Clocks
AD0TM=1
Low Power
or Convert
Track
1
2
3
Convert
4
5
6
7
8
9
Low Power Mode
10 11
SAR Clocks
AD0TM=0
Track or
Convert
Convert
Track
Figure 5.4. 12-Bit ADC Track and Conversion Example Timing
Rev. 1.8
55
C8051F310/1/2/3/4/5/6/7
5.3.3. Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum
tracking time is required before an accurate conversion can be performed. This tracking time is determined
by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. In low-power tracking mode, three SAR clocks are used for tracking at the
start of every conversion. For most applications, these three SAR clocks will meet the minimum tracking
time requirements.
Figure 5.5 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice
that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a
given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature
Sensor output or VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum
settling time requirements.
Equation 5.1. ADC0 Settling Time Requirements
n
2
t = ln ------- R TOTAL C SAMPLE
SA
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the AMUX0 resistance and any external source resistance.
n is the ADC resolution in bits (12).
Differential Mode
Single-Ended Mode
MUX Select
MUX Select
Px.x
Px.x
RMUX = 5k
RMUX = 5k
CSAMPLE = 5pF
CSAMPLE = 5pF
RCInput= RMUX * CSAMPLE
RCInput= RMUX * CSAMPLE
CSAMPLE = 5pF
Px.x
RMUX = 5k
MUX Select
Figure 5.5. ADC0 Equivalent Input Circuits
56
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select
R
R
R
R/W
R/W
R/W
R/W
-
-
-
AMX0P4
AMX0P3
AMX0P2
AMX0P1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
AMX0P0 00000000
Bit0
SFR Address:
0xBB
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0P4–0: AMUX0 Positive Input Selection
AMX0P4–0
00000
00001
00010
00011
00100
00101
00110
ADC0 Positive Input
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
00111
P1.7(1)
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
01000
01001
01010
01011
01100
01101
01110
01111
P1.6(1)
P2.6(1)
10000
P2.7(1)
P3.0
10001(2)
P3.1(2)
10010(2)
P3.2(2)
10011(2)
P3.3(2)
10100(2)
10101–11101
11110
11111
P3.4(2)
RESERVED
Temp Sensor
VDD
Notes:
1. Only applies to C8051F310/1/2/3/4/5; selection
RESERVED on C8051F316/7 devices.
2. Only applies to C8051F310/2; selection RESERVED on
C8051F311/3/6/7 devices.
Rev. 1.8
57
C8051F310/1/2/3/4/5/6/7
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select
R
R
R
R/W
R/W
R/W
R/W
-
-
-
AMX0N4
AMX0N3
AMX0N2
AMX0N1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
AMX0N0 00000000
Bit0
SFR Address:
0xBA
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0N4–0: AMUX0 Negative Input Selection.
Note that when GND is selected as the Negative Input, ADC0 operates in Single-ended
mode. For all other Negative Input selections, ADC0 operates in Differential mode.
AMX0N4–0
00000
00001
00010
00011
00100
00101
00110
ADC0 Negative Input
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
00111
P1.7(1)
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
01000
01001
01010
01011
01100
01101
01110
01111
P1.6(1)
P2.6(1)
10000
P2.7(1)
P3.0
10001(2)
P3.1(2)
10010(2)
P3.2(2)
10011(2)
P3.3(2)
10100(2)
10101–11101
11110
11111
P3.4(2)
RESERVED
VREF
GND (ADC in Single-Ended Mode)
Notes:
1. Only applies to C8051F310/1/2/3/4/5; selection
RESERVED on C8051F316/7 devices.
2. Only applies to C8051F310/2; selection RESERVED on
C8051F311/3/6/7 devices.
58
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 5.3. ADC0CF: ADC0 Configuration
R/W
R/W
R/W
R/W
AD0SC4
AD0SC3
AD0SC2
AD0SC1
Bit7
Bit6
Bit5
Bit4
R/W
R/W
AD0SC0 AD0LJST
Bit3
Bit2
R/W
R/W
Reset Value
-
-
11111000
Bit1
Bit0
SFR Address:
0xBC
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in bits AD0SC4–0. SAR Conversion clock requirements are given in Table 5.1.
SYSCLK
AD0SC = ---------------------- – 1
CLK SAR
Bit2:
AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
Bits1–0: UNUSED. Read = 00b; Write = don’t care.
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xBE
Bits7–0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–2 are the sign extension of Bit1. Bits 1–0 are the upper 2 bits of the
12-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 12-bit ADC0 Data Word.
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBD
Bits7–0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 12-bit Data Word.
For AD0LJST = 1: Bits 7–6 are the lower 2 bits of the 12-bit Data Word. Bits 5–0 will always
read ‘0’.
Rev. 1.8
59
C8051F310/1/2/3/4/5/6/7
SFR Definition 5.6. ADC0CN: ADC0 Control
R/W
R/W
AD0EN
AD0TM
Bit7
Bit6
R/W
R/W
R/W
R/W
R/W
R/W
AD0INT AD0BUSY AD0WINT AD0CM2 AD0CM1
Bit5
Bit4
Bit3
Bit2
Bit1
AD0CM0 00000000
Bit0
(bit addressable)
Bit7:
Reset Value
SFR Address:
0xE8
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
Bit6:
AD0TM: ADC0 Track Mode Bit.
0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a conversion is
in progress.
1: Low-power Track Mode: Tracking Defined by AD0CM2-0 bits (see below).
Bit5:
AD0INT: ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since the last time AD0INT was cleared.
1: ADC0 has completed a data conversion.
Bit4:
AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 conversion is complete or a conversion is not currently in progress. AD0INT is set to
logic 1 on the falling edge of AD0BUSY.
1: ADC0 conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM2-0 = 000b
Bit3:
AD0WINT: ADC0 Window Compare Interrupt Flag.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
Bits2–0: AD0CM2–0: ADC0 Start of Conversion Mode Select.
When AD0TM = 0:
000: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
001: ADC0 conversion initiated on overflow of Timer 0.
010: ADC0 conversion initiated on overflow of Timer 2.
011: ADC0 conversion initiated on overflow of Timer 1.
100: ADC0 conversion initiated on rising edge of external CNVSTR.
101: ADC0 conversion initiated on overflow of Timer 3.
11x: Reserved.
When AD0TM = 1:
000: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR clocks, followed by conversion.
001: Tracking initiated on overflow of Timer 0 and lasts 3 SAR clocks, followed by conversion.
010: Tracking initiated on overflow of Timer 2 and lasts 3 SAR clocks, followed by conversion.
011: Tracking initiated on overflow of Timer 1 and lasts 3 SAR clocks, followed by conversion.
100: ADC0 tracks only when CNVSTR input is logic low; conversion starts on rising CNVSTR
edge.
101: Tracking initiated on overflow of Timer 3 and lasts 3 SAR clocks, followed by conversion.
11x: Reserved.
60
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
5.4.
Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-programmed limits, and notifies the system when a desired condition is detected. This is especially effective in
an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system
response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in
polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL)
registers hold the comparison values. The window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0
Less-Than and ADC0 Greater-Than registers.
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xC4
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xC3
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
Rev. 1.8
61
C8051F310/1/2/3/4/5/6/7
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xC6
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xC5
Bits7–0: Low byte of ADC0 Less-Than Data Word.
62
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
5.4.1. Window Detector In Single-Ended Mode
Figure 5.6 shows two example window comparisons for right-justified, single-ended data, with
ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). In single-ended mode,
the input voltage can range from ‘0’ to VREF x (1023/1024) with respect to GND, and is represented by a
10-bit unsigned integer value. In the left example, an AD0WINT interrupt will be generated if the ADC0
conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and
ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt
will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and
ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 5.7 shows an example using left-justified data with the same comparison values.
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
Input Voltage
(Px.x - GND)
0x03FF
VREF x (1023/1024)
0x03FF
AD0WINT
not affected
AD0WINT=1
0x0081
VREF x (128/1024)
0x0080
0x0081
ADC0LTH:ADC0LTL
VREF x (128/1024)
0x007F
0x0080
0x007F
AD0WINT=1
VREF x (64/1024)
0x0041
0x0040
ADC0GTH:ADC0GTL
VREF x (64/1024)
0x003F
0x0041
0x0040
ADC0GTH:ADC0GTL
AD0WINT
not affected
ADC0LTH:ADC0LTL
0x003F
AD0WINT=1
AD0WINT
not affected
0
0x0000
0
0x0000
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
Input Voltage
(Px.x - GND)
0xFFC0
VREF x (1023/1024)
0xFFC0
AD0WINT
not affected
AD0WINT=1
0x2040
VREF x (128/1024)
0x2000
0x2040
ADC0LTH:ADC0LTL
VREF x (128/1024)
0x1FC0
0x2000
0x1FC0
AD0WINT=1
0x1040
VREF x (64/1024)
0x1000
0x1040
ADC0GTH:ADC0GTL
VREF x (64/1024)
0x0FC0
0x1000
0x0000
AD0WINT
not affected
ADC0LTH:ADC0LTL
0x0FC0
AD0WINT=1
AD0WINT
not affected
0
ADC0GTH:ADC0GTL
0
0x0000
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data
Rev. 1.8
63
C8051F310/1/2/3/4/5/6/7
5.4.2. Window Detector In Differential Mode
Figure 5.8 shows two example window comparisons for right-justified, differential data, with
ADC0LTH:ADC0LTL = 0x0040 (+64d) and ADC0GTH:ADC0GTH = 0xFFFF (-1d). In differential mode, the
measurable voltage between the input pins is between -VREF and VREF*(511/512). Output codes are represented as 12-bit 2’s complement signed integers. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL
and ADC0LTH:ADC0LTL (if 0xFFFF (-1d) < ADC0H:ADC0L < 0x0040 (64d)). In the right example, an
AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the
ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0xFFFF (-1d) or ADC0H:ADC0L > 0x0040 (+64d)).
Figure 5.9 shows an example using left-justified data with the same comparison values.
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - Px.x)
VREF x (511/512)
Input Voltage
(Px.x - Px.x)
0x01FF
VREF x (511/512)
0x01FF
AD0WINT
not affected
AD0WINT=1
0x0041
VREF x (64/512)
0x0040
0x0041
ADC0LTH:ADC0LTL
VREF x (64/512)
0x003F
0x0040
0x003F
AD0WINT=1
0x0000
VREF x (-1/512)
0xFFFF
0x0000
ADC0GTH:ADC0GTL
VREF x (-1/512)
0xFFFE
0xFFFF
ADC0GTH:ADC0GTL
AD0WINT
not affected
ADC0LTH:ADC0LTL
0xFFFE
AD0WINT=1
AD0WINT
not affected
-VREF
0x0200
-VREF
0x0200
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - Px.x)
VREF x (511/512)
Input Voltage
(Px.x - Px.y)
0x7FC0
VREF x (511/512)
0x7FC0
AD0WINT
not affected
AD0WINT=1
0x1040
VREF x (64/512)
0x1000
0x1040
ADC0LTH:ADC0LTL
VREF x (64/512)
0x0FC0
0x1000
0x0FC0
AD0WINT=1
0x0000
VREF x (-1/512)
0xFFC0
0x0000
ADC0GTH:ADC0GTL
VREF x (-1/512)
0xFF80
0xFFC0
AD0WINT
not affected
ADC0LTH:ADC0LTL
0xFF80
AD0WINT=1
AD0WINT
not affected
-VREF
ADC0GTH:ADC0GTL
0x8000
-VREF
0x8000
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data
64
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Table 5.1. ADC0 Electrical Characteristics
VDD = 3.0 V, VREF = 2.40 V (REFSL=0), –40 to +85 °C unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
12
Integral Nonlinearity
Differential Nonlinearity
Guaranteed Monotonic
Offset Error
Full Scale Error
Differential mode
Offset Temperature Coefficient
bits
—
±0.5
±1
LSB
—
±0.5
±1
LSB
–12
1
+12
LSB
–15
–5
+5
LSB
—
3.6
—
ppm/°C
Dynamic Performance (10 kHz sine-wave Single-ended input, 0 to 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion
53
55.5
—
dB
—
–67
—
dB
—
78
—
dB
SAR Conversion Clock
—
—
3
MHz
Conversion Time in SAR Clocks
10
—
—
clocks
Track/Hold Acquisition Time
300
—
—
ns
—
—
200
ksps
Input Voltage Range
0
—
VREF
V
Input Capacitance
—
5
—
pF
Temperature Sensor
—
—
—
Linearity*
—
±0.5
—
°C
Gain*
—
3350 ± 10
—
µV / °C
(Temp = 0 °C)
—
897 ± 31
—
mV
Operating Mode, 200 ksps
—
400
900
µA
—
±0.3
—
mV/V
Total Harmonic Distortion
Up to the 5th harmonic
Spurious-Free Dynamic Range
Conversion Rate
Throughput Rate
Analog Inputs
Offset*
Power Specifications
Power Supply Current
(VDD supplied to ADC0)
Power Supply Rejection
*Note: Represents one standard deviation from the mean. Includes ADC offset, gain, and linearity variations.
Rev. 1.8
65
C8051F310/1/2/3/4/5/6/7
NOTES:
66
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
6.
Voltage Reference (C8051F310/1/2/3/6 only)
The voltage reference MUX on C8051F310/1/2/3/6 devices is configurable to use an externally connected
voltage reference, or the power supply voltage (see Figure 6.1). The REFSL bit in the Reference Control
register (REF0CN) selects the reference source. For an external source, REFSL should be set to ‘0’; For
VDD as the reference source, REFSL should be set to ‘1’.
The BIASE bit enables the internal voltage bias generator, which is used by the ADC, Temperature Sensor,
and Internal Oscillator. This bit is forced to logic 1 when any of the aforementioned peripherals is enabled.
The bias generator may be enabled manually by writing a ‘1’ to the BIASE bit in register REF0CN; see
SFR Definition 6.1 for REF0CN register details. The electrical specifications for the voltage reference circuit are given in Table 6.1.
Important Note About the VREF Input: Port pin P0.0 is used as the external VREF input. When using an
external voltage reference, P0.0 should be configured as analog input and skipped by the Digital Crossbar.
To configure P0.0 as analog input, set to ‘0’ Bit0 in register P0MDIN. To configure the Crossbar to skip
P0.0, set to ‘1’ Bit0 in register P0SKIP. Refer to Section “13. Port Input/Output” on page 129 for complete Port I/O configuration details.
The temperature sensor connects to the highest order input of the ADC0 positive input multiplexer (see
Section “5.1. Analog Multiplexer” on page 51 for details). The TEMPE bit in register REF0CN
enables/disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in meaningless data.
BIASE
REFSL
TEMPE
REF0CN
EN
Bias Generator
To ADC, Internal
Oscillator
IOSCEN
VDD
R1
External
Voltage
Reference
Circuit
EN
VREF
Temp Sensor
To Analog Mux
0
Internal
VREF
(to ADC)
GND
VDD
1
Figure 6.1. Voltage Reference Functional Block Diagram
Rev. 1.8
67
C8051F310/1/2/3/4/5/6/7
SFR Definition 6.1. REF0CN: Reference Control
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
R/W
R/W
REFSL
TEMPE
BIASE
R/W
Bit3
Bit2
Bit1
Reset Value
00000000
Bit0
SFR Address:
0xD1
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3:
REFSL: Voltage Reference Select.
This bit selects the source for the internal voltage reference.
0: VREF input pin used as voltage reference.
1: VDD used as voltage reference.
Bit2:
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
Bit1:
BIASE: Internal Analog Bias Generator Enable Bit. (Must be ‘1’ if using ADC).
0: Internal Bias Generator off.
1: Internal Bias Generator on.
Bit0:
UNUSED. Read = 0b. Write = don’t care.
Table 6.1. External Voltage Reference Circuit Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C unless otherwise specified
Parameter
Conditions
68
Typ
0
Input Voltage Range
Input Current
Min
Sample Rate = 200 ksps;
VREF = 3.0 V
Rev. 1.8
12
Max
Units
VDD
V
µA
C8051F310/1/2/3/4/5/6/7
7.
Comparators
C8051F31x devices include two on-chip programmable voltage comparators: Comparator0 is shown in
Figure 7.1; Comparator1 is shown in Figure 7.2. The two comparators operate identically with the following
exceptions: (1) Their input selections differ as shown in Figure 7.1 and Figure 7.2; (2) Comparator0 can be
used as a reset source.
The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two
outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an
asynchronous “raw” output (CP0A, CP1A). The asynchronous CP0A signal is available even when the
system clock is not active. This allows the Comparator to operate and generate an output with the device
in STOP mode. When assigned to a Port pin, the Comparator output may be configured as open drain or
push-pull (see Section “13.2. Port I/O Initialization” on page 133). Comparator0 may also be used as a
reset source (see Section “9.5. Comparator0 Reset” on page 108).
The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 7.2). The CMX0P1-CMX0P0
bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative
input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 7.5). The CMX1P1CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the Comparator1
negative input.
Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be configured as analog inputs in their associated Port configuration register, and configured to be skipped by the
Crossbar (for details on Port configuration, see Section “13.3. General Purpose Port I/O” on page 135).
CPT0CN
CMX0N1
CMX0N0
VDD
CP0FIF
CP0HYP1
CP0HYP0
CP0
Interrupt
CP0HYN1
CP0HYN0
CMX0P1
CMX0P0
CP0
Rising-edge
P1.0
CP0
Falling-edge
P1.4
P2.0
CP0 +
Interrupt
Logic
P2.4
CP0
+
D
P1.5
SET
CLR
Q
Q
D
SET
CLR
Q
Q
Crossbar
P1.1
(SYNCHRONIZER)
GND
CP0 -
P2.1
CP0A
Reset
Decision
Tree
P2.5
CPT0MD
CPT0MX
CP0EN
CP0OUT
CP0RIF
CP0RIE
CP0FIE
CP0MD1
CP0MD0
Figure 7.1. Comparator0 Functional Block Diagram
Rev. 1.8
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C8051F310/1/2/3/4/5/6/7
The Comparator output can be polled in software, used as an interrupt source, and/or routed to a Port pin.
When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system
clock; the asynchronous output is available even in STOP mode (with no system clock active). When disabled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state,
and its supply current falls to less than 100 nA. See Section “13.1. Priority Crossbar Decoder” on
page 131 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be
externally driven from –0.25 V to (VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in Table 7.1.
CPT1CN
CPT1MX
The Comparator response time may be configured in software via the CPTnMD registers (see SFR Definition 7.3 and SFR Definition 7.6). Selecting a longer response time reduces the Comparator supply current.
See Table 7.1 for complete timing and current consumption specifications.
CMX1N1
CMX1N0
CP1EN
CP1OUT
CP1RIF
CP1FIF
VDD
CP1HYP1
CP1HYP0
CP1HYN1
CP1HYN0
CP1
Interrupt
CMX1P1
CMX1P0
CP1
Rising-edge
P1.2
CP1
Falling-edge
P1.6
P2.2
CP1 +
Interrupt
Logic
P2.6
CP1
+
D
-
CLR
Q
Q
D
SET
CLR
Q
Q
Crossbar
P1.3
P1.7
SET
(SYNCHRONIZER)
CP1 -
GND
P2.3
CP1A
Reset
Decision
Tree
CPT1MD
P2.7
CP1RIE
CP1FIE
CP1MD1
CP1MD0
Figure 7.2. Comparator1 Functional Block Diagram
70
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VIN+
VIN-
CP0+
CP0-
+
CP0
_
OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
INPUTS
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Positive Hysteresis
Disabled
Maximum
Negative Hysteresis
Maximum
Positive Hysteresis
Figure 7.3. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN (for
n = 0 or 1). The user can program both the amount of hysteresis voltage (referred to the input voltage) and
the positive and negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN
(shown in SFR Definition 7.1 and SFR Definition 7.4). The amount of negative hysteresis voltage is
determined by the settings of the CPnHYN bits. As shown in Table 7.1, settings of 20, 10 or 5 mV of
negative hysteresis can be programmed, or negative hysteresis can be disabled. In a similar way, the
amount of positive hysteresis is determined by the setting the CPnHYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “8.3. Interrupt Handler” on page 93). The CPnFIF flag is set
to logic 1 upon a Comparator falling-edge interrupt, and the CPnRIF flag is set to logic 1 upon the Comparator rising-edge interrupt. Once set, these bits remain set until cleared by software. The output state of the
Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0.
The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0.
Note that false rising edges and falling edges can be detected when the comparator is first powered-on or
if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the
rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is
enabled or its mode bits have been changed. This Power Up Time is specified in Table 7.1 on page 78.
Rev. 1.8
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SFR Definition 7.1. CPT0CN: Comparator0 Control
R/W
R
R/W
R/W
CP0EN
CP0OUT
CP0RIF
CP0FIF
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9B
Bit7:
CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6:
CP0OUT: Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5:
CP0RIF: Comparator0 Rising-Edge Interrupt Flag.
0: No Comparator0 Rising Edge Interrupt has occurred since this flag was last cleared.
1: Comparator0 Rising Edge Interrupt has occurred.
Bit4:
CP0FIF: Comparator0 Falling-Edge Interrupt Flag.
0: No Comparator0 Falling-Edge Interrupt has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge Interrupt has occurred.
Bits3–2: CP0HYP1-0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP0HYN1-0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
72
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SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection
R/W
R/W
-
-
Bit7
Bit6
R/W
R/W
CMX0N1 CMX0N0
Bit5
Bit4
R/W
R/W
R/W
-
-
CMX0P1
Bit3
Bit2
Bit1
R/W
Reset Value
CMX0P0 00000000
Bit0
SFR Address:
0x9F
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bits5–4: CMX0N1–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
CMX0N1 CMX0N0
0
0
0
1
1
0
1
1
Negative Input
P1.1
P1.5
P2.1
P2.5
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CMX0P1–CMX0P0: Comparator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
CMX0P1 CMX0P0
0
0
0
1
1
0
1
1
Positive Input
P1.0
P1.4
P2.0
P2.4
Rev. 1.8
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SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection
R/W
R/W
R/W
R/W
R/W
R/W
-
-
CP0RIE
CP0FIE
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
Reset Value
CP0MD1 CP0MD0 00000010
Bit1
Bit0
SFR Address:
0x9D
Bits7–6: UNUSED. Read = 00b. Write = don’t care.
Bit5:
CP0RIE: Comparator Rising-Edge Interrupt Enable.
0: Comparator rising-edge interrupt disabled.
1: Comparator rising-edge interrupt enabled.
Bit4:
CP0FIE: Comparator Falling-Edge Interrupt Enable.
0: Comparator falling-edge interrupt disabled.
1: Comparator falling-edge interrupt enabled.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
Mode
0
1
2
3
74
CP0MD1
0
0
1
1
CP0MD0
0
1
0
1
CP0 Response Time (TYP)
Fastest Response Time
—
—
Lowest Power Consumption
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 7.4. CPT1CN: Comparator1 Control
R/W
R
R/W
R/W
CP1EN
CP1OUT
CP1RIF
CP1FIF
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9A
Bit7:
CP1EN: Comparator1 Enable Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
Bit6:
CP1OUT: Comparator1 Output State Flag.
0: Voltage on CP1+ < CP1–.
1: Voltage on CP1+ > CP1–.
Bit5:
CP1RIF: Comparator1 Rising-Edge Interrupt Flag.
0: No Comparator1 Rising Edge Interrupt has occurred since this flag was last cleared.
1: Comparator1 Rising Edge Interrupt has occurred.
Bit4:
CP1FIF: Comparator1 Falling-Edge Interrupt Flag.
0: No Comparator1 Falling-Edge Interrupt has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge Interrupt has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev. 1.8
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SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection
R/W
R/W
-
-
Bit7
Bit6
R/W
R/W
CMX1N1 CMX1N0
Bit5
Bit4
R/W
R/W
R/W
-
-
CMX1P1
Bit3
Bit2
Bit1
R/W
Reset Value
CMX1P0 00000000
Bit0
SFR Address:
0x9E
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bits5–4: CMX1N1–CMX1N0: Comparator1 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator1 negative input.
CMX1N1 CMX1N0
0
0
0
1
1
0
1
1
Negative Input
P1.3
P1.7
P2.3
P2.7
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CMX1P1–CMX1P0: Comparator1 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator1 positive input.
CMX1P1 CMX1P0
0
0
0
1
1
0
1
1
76
Positive Input
P1.2
P1.6
P2.2
P2.6
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection
R/W
R/W
R/W
R/W
R/W
R/W
-
-
CP1RIE
CP1FIE
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
Reset Value
CP1MD1 CP1MD0 00000010
Bit1
Bit0
SFR Address:
0x9C
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit5:
CP1RIE: Comparator Rising-Edge Interrupt Enable.
0: Comparator rising-edge interrupt disabled
1: Comparator rising-edge interrupt enabled.
Bit4:
CP1FIE: Comparator Falling-Edge Interrupt Enable.
0: Comparator falling-edge interrupt disabled.
1: Comparator falling-edge interrupt enabled.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select.
These bits select the response time for Comparator1.
Mode
0
1
2
3
CP1MD1
0
0
1
1
CP1MD0
0
1
0
1
CP1 Response Time (TYP)
Fastest Response Time
—
—
Lowest Power Consumption
Rev. 1.8
77
C8051F310/1/2/3/4/5/6/7
Table 7.1. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherwise noted.
All specifications apply to both Comparator0 and Comparator1 unless otherwise noted.
Parameter
Response Time:
Mode 0, Vcm1 = 1.5 V
Response Time:
Mode 1, Vcm1 = 1.5 V
Response Time:
Mode 2, Vcm1 = 1.5 V
Response Time:
Mode 3, Vcm1 = 1.5 V
Conditions
Min
Typ
Max
Units
CP0+ – CP0– = 100 mV
—
100
—
ns
CP0+ – CP0– = –100 mV
—
250
—
ns
CP0+ – CP0– = 100 mV
—
175
—
ns
CP0+ – CP0– = –100 mV
—
500
—
ns
CP0+ – CP0– = 100 mV
—
320
—
ns
CP0+ – CP0– = –100 mV
—
1100
—
ns
CP0+ – CP0– = 100 mV
—
1050
—
ns
CP0+ – CP0– = –100 mV
—
5200
—
ns
—
1.5
4
mV/V
Common-Mode Rejection Ratio
Positive Hysteresis 1
CP0HYP1-0 = 00
—
0
1
mV
Positive Hysteresis 2
CP0HYP1-0 = 01
2
5
7
mV
Positive Hysteresis 3
CP0HYP1-0 = 10
5
10
13
mV
Positive Hysteresis 4
CP0HYP1-0 = 11
12
20
25
mV
Negative Hysteresis 1
CP0HYN1-0 = 00
0
1
mV
Negative Hysteresis 2
CP0HYN1-0 = 01
2
5
7
mV
Negative Hysteresis 3
CP0HYN1-0 = 10
5
10
13
mV
Negative Hysteresis 4
CP0HYN1-0 = 11
12
20
25
mV
–0.25
—
VDD +
0.25
V
Input Capacitance
—
7
—
pF
Input Bias Current
—
1
—
nA
Input Offset Voltage
–5
—
+5
mV
Power Supply Rejection2
—
0.1
1
mV/V
Power-up Time
—
10
—
µs
Mode 0
—
7.6
20
µA
Mode 1
—
3.2
10
µA
Mode 2
—
1.3
5
µA
Mode 3
—
0.4
2.5
µA
Inverting or Non-Inverting Input
Voltage Range
Power Supply
Supply Current at DC
Notes:
1. Vcm is the common-mode voltage on CP0+ and CP0–.
2. Guaranteed by design and/or characterization.
78
Rev. 1.8
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8.
CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The MCU family has a superset of all the peripherals included with a standard 8051. Included are
four 16-bit counter/timers (see description in Section 17), an enhanced full-duplex UART (see description
in Section 15), an Enhanced SPI (see description in Section 16), 256 bytes of internal RAM, 128 byte
Special Function Register (SFR) address space (Section 8.2.6), and 29 Port I/O (see description in Section 13). The CIP-51 also includes on-chip debug hardware (see description in Section 20), and interfaces
directly with the analog and digital subsystems providing a complete data acquisition or control-system
solution in a single integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 8.1 for a block diagram).
The CIP-51 includes the following features:
-
- Fully Compatible with MCS-51 Instruction
Set
- 25 MIPS Peak Throughput with 25 MHz
Clock
- 0 to 25 MHz Clock Frequency
- 256 Bytes of Internal RAM
29 Port I/O
Extended Interrupt Handler
Reset Input
Power Management Modes
On-chip Debug Logic
Program and Data Memory Security
D8
D8
ACCUMULATOR
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
PSW
D8
D8
D8
ALU
SRAM
(256 X 8)
D8
DATA BUS
B REGISTER
D8
D8
D8
DATA BUS
DATA BUS
SFR_ADDRESS
BUFFER
D8
DATA POINTER
D8
D8
SFR
BUS
INTERFACE
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
DATA BUS
PC INCREMENTER
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
MEM_ADDRESS
D8
MEM_CONTROL
A16
MEMORY
INTERFACE
MEM_WRITE_DATA
MEM_READ_DATA
PIPELINE
RESET
D8
CONTROL
LOGIC
SYSTEM_IRQs
CLOCK
D8
STOP
IDLE
POWER CONTROL
REGISTER
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
Figure 8.1. CIP-51 Block Diagram
Rev. 1.8
79
C8051F310/1/2/3/4/5/6/7
Performance
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has
a total of 109 instructions. The table below shows the total number of instructions that require each execution time.
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Number of Instructions
26
50
5
14
7
3
1
2
1
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Silicon Labs 2-Wire Development Interface (C2). The re-programmable Flash
can also be read and changed a single byte at a time by the application software using the MOVC and
MOVX instructions. This feature allows program memory to be used for non-volatile data storage as well
as updating program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints, starting, stopping and single stepping through program execution (including interrupt service
routines), examination of the program's call stack, and reading/writing the contents of registers and memory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or
other on-chip resources. C2 details can be found in Section “20. C2 Interface” on page 223.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs provides an integrated development environment (IDE) including an editor, evaluation compiler, assembler,
debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient in-system device programming and debugging. Third party macro assemblers and C compilers are also available.
8.1.
Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051.
8.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock
cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 8.1 is the
80
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
8.1.2. MOVX Instruction and Program Memory
The MOVX instruction is typically used to access external data memory (Note: the C8051F31x does not
support external data or program memory). In the CIP-51, the MOVX write instruction is used to accesses
external RAM and the on-chip program memory space implemented as re-programmable Flash memory.
The Flash access feature provides a mechanism for the CIP-51 to update program code and use the program memory space for non-volatile data storage. Refer to Section “10. Flash Memory” on page 111 for
further details.
Table 8.1. CIP-51 Instruction Set Summary
Mnemonic
ADD A, Rn
ADD A, direct
ADD A, @Ri
ADD A, #data
ADDC A, Rn
ADDC A, direct
ADDC A, @Ri
ADDC A, #data
SUBB A, Rn
SUBB A, direct
SUBB A, @Ri
SUBB A, #data
INC A
INC Rn
INC direct
INC @Ri
DEC A
DEC Rn
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
DA A
ANL A, Rn
ANL A, direct
ANL A, @Ri
ANL A, #data
ANL direct, A
ANL direct, #data
ORL A, Rn
Description
Arithmetic Operations
Add register to A
Add direct byte to A
Add indirect RAM to A
Add immediate to A
Add register to A with carry
Add direct byte to A with carry
Add indirect RAM to A with carry
Add immediate to A with carry
Subtract register from A with borrow
Subtract direct byte from A with borrow
Subtract indirect RAM from A with borrow
Subtract immediate from A with borrow
Increment A
Increment register
Increment direct byte
Increment indirect RAM
Decrement A
Decrement register
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
Divide A by B
Decimal adjust A
Logical Operations
AND Register to A
AND direct byte to A
AND indirect RAM to A
AND immediate to A
AND A to direct byte
AND immediate to direct byte
OR Register to A
Rev. 1.8
Bytes
Clock
Cycles
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
1
1
2
1
1
1
1
1
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
2
1
1
2
2
1
4
8
1
1
2
1
2
2
3
1
1
2
2
2
2
3
1
81
C8051F310/1/2/3/4/5/6/7
Table 8.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
Description
ORL A, direct
ORL A, @Ri
ORL A, #data
ORL direct, A
ORL direct, #data
XRL A, Rn
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
XRL direct, #data
CLR A
CPL A
RL A
RLC A
RR A
RRC A
SWAP A
OR direct byte to A
OR indirect RAM to A
OR immediate to A
OR A to direct byte
OR immediate to direct byte
Exclusive-OR Register to A
Exclusive-OR direct byte to A
Exclusive-OR indirect RAM to A
Exclusive-OR immediate to A
Exclusive-OR A to direct byte
Exclusive-OR immediate to direct byte
Clear A
Complement A
Rotate A left
Rotate A left through Carry
Rotate A right
Rotate A right through Carry
Swap nibbles of A
Data Transfer
Move Register to A
Move direct byte to A
Move indirect RAM to A
Move immediate to A
Move A to Register
Move direct byte to Register
Move immediate to Register
Move A to direct byte
Move Register to direct byte
Move direct byte to direct byte
Move indirect RAM to direct byte
Move immediate to direct byte
Move A to indirect RAM
Move direct byte to indirect RAM
Move immediate to indirect RAM
Load DPTR with 16-bit constant
Move code byte relative DPTR to A
Move code byte relative PC to A
Move external data (8-bit address) to A
Move A to external data (8-bit address)
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
Pop direct byte from stack
Exchange Register with A
Exchange direct byte with A
MOV A, Rn
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct, direct
MOV direct, @Ri
MOV direct, #data
MOV @Ri, A
MOV @Ri, direct
MOV @Ri, #data
MOV DPTR, #data16
MOVC A, @A+DPTR
MOVC A, @A+PC
MOVX A, @Ri
MOVX @Ri, A
MOVX A, @DPTR
MOVX @DPTR, A
PUSH direct
POP direct
XCH A, Rn
XCH A, direct
82
2
1
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
Clock
Cycles
2
2
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
2
2
2
1
2
2
2
2
3
2
3
2
2
2
3
3
3
3
3
3
3
2
2
1
2
Bytes
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Table 8.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
Description
XCH A, @Ri
XCHD A, @Ri
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
Boolean Manipulation
Clear Carry
Clear direct bit
Set Carry
Set direct bit
Complement Carry
Complement direct bit
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
Jump if Carry is not set
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
Program Branching
Absolute subroutine call
Long subroutine call
Return from subroutine
Return from interrupt
Absolute jump
Long jump
Short jump (relative address)
Jump indirect relative to DPTR
Jump if A equals zero
Jump if A does not equal zero
Compare direct byte to A and jump if not equal
Compare immediate to A and jump if not equal
Compare immediate to Register and jump if not
equal
Compare immediate to indirect and jump if not
equal
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
CLR C
CLR bit
SETB C
SETB bit
CPL C
CPL bit
ANL C, bit
ANL C, /bit
ORL C, bit
ORL C, /bit
MOV C, bit
MOV bit, C
JC rel
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
ACALL addr11
LCALL addr16
RET
RETI
AJMP addr11
LJMP addr16
SJMP rel
JMP @A+DPTR
JZ rel
JNZ rel
CJNE A, direct, rel
CJNE A, #data, rel
CJNE Rn, #data, rel
CJNE @Ri, #data, rel
DJNZ Rn, rel
DJNZ direct, rel
NOP
1
1
Clock
Cycles
2
2
1
2
1
2
1
2
2
2
2
2
2
2
2
2
3
3
3
1
2
1
2
1
2
2
2
2
2
2
2
2/3
2/3
3/4
3/4
3/4
2
3
1
1
2
3
2
1
2
2
3
3
3
4
5
5
3
4
3
3
2/3
2/3
3/4
3/4
3
3/4
3
4/5
2
3
1
2/3
3/4
1
Bytes
Rev. 1.8
83
C8051F310/1/2/3/4/5/6/7
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0–R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through R0 or R1.
rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00–
0x7F) or an SFR (0x80–0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2 kB page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 8 kB program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
84
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
8.2.
Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. The CIP-51 memory organization is
shown in Figure 8.2.
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(Flash)
0xFF
C8051F310/1
0x3E00
RESERVED
0x80
0x7F
0x3DFF
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
16 kB Flash
0x30
0x2F
(In-System
Programmable in 512
Byte Sectors)
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0x0000
0xFFFF
C8051F312/3/4/5
0x2000
RESERVED
Same 1024 bytes as from
0x0000 to 0x03FF, wrapped
on 1 kB boundaries
0x1FFF
8 kB Flash
0x0400
(In-System
Programmable in 512
Byte Sectors)
0x03FF
0x0000
XRAM - 1024 Bytes
(accessable using MOVX
instruction)
0x0000
Figure 8.2. Memory Map
8.2.1. Program Memory
The CIP-51 core has a 64k-byte program memory space. The C8051F310/1 and C8051F312/3/4/5 implement 16k and 8 kB, respectively, of this program memory space as in-system, re-programmable Flash
memory, organized in a contiguous block from addresses 0x0000 to 0x3FFF or 0x0000 to 0x1FFF.
Addresses above 0x3E00 are reserved on the 16 kB devices.
Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory
by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for nonvolatile data storage. Refer to Section “10. Flash Memory” on page 111 for further details.
Rev. 1.8
85
C8051F310/1/2/3/4/5/6/7
8.2.2. Data Memory
The CIP-51 includes 256 bytes of internal RAM mapped into the data memory space from 0x00 through
0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting
of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as
bytes or as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 8.2 illustrates the data memory organization of the CIP-51.
8.2.3. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only
one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1
(PSW.4), select the active register bank (see description of the PSW in SFR Definition 8.4). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes
use registers R0 and R1 as index registers.
8.2.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destination).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV
C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
8.2.5. Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The stack depth can extend up
to 256 bytes.
86
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
8.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional
SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 8.2 lists the SFRs implemented in the CIP-51 System Controller.
The SFR registers are accessed anytime the direct addressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are bitaddressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied
addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate
effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 8.3,
for a detailed description of each register.
Table 8.2. Special Function Register (SFR) Memory Map
F8
F0
E8
E0
D8
D0
C8
C0
B8
B0
A8
A0
98
90
88
80
SPI0CN
PCA0L
PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4
B
P0MDIN
P1MDIN
P2MDIN
P3MDIN
ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3
ACC
XBR0
XBR1
IT01CF
PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3
PSW
REF0CN
P0SKIP
P1SKIP
TMR2CN
TMR2RLL TMR2RLH
TMR2L
TMR2H
SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL
IP
AMX0N
AMX0P
ADC0CF
ADC0L
P3
OSCXCN
OSCICN
OSCICL
IE
CLKSEL
EMI0CN
P2
SPI0CFG SPI0CKR
SPI0DAT P0MDOUT P1MDOUT
SCON0
SBUF0
CPT1CN
CPT0CN
CPT1MD
CPT0MD
P1
TMR3CN TMR3RLL TMR3RLH
TMR3L
TMR3H
TCON
TMOD
TL0
TL1
TH0
TH1
P0
SP
DPL
DPH
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
PCA0CPH4 VDM0CN
EIP1
PCA0CPH3 RSTSRC
EIE1
PCA0CPM4
P2SKIP
ADC0LTH
ADC0H
FLSCL
FLKEY
P2MDOUT P3MDOUT
CPT1MX
CPT0MX
CKCON
6(E)
PSCTL
PCON
7(F)
(bit addressable)
Rev. 1.8
87
C8051F310/1/2/3/4/5/6/7
Table 8.3. Special Function Registers
Register
Address
Description
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
ACC
0xE0
Accumulator
ADC0CF
0xBC
ADC0 Configuration
ADC0CN
0xE8
ADC0 Control
ADC0GTH
0xC4
ADC0 Greater-Than Compare High
ADC0GTL
0xC3
ADC0 Greater-Than Compare Low
ADC0H
0xBE
ADC0 High
ADC0L
0xBD
ADC0 Low
ADC0LTH
0xC6
ADC0 Less-Than Compare Word High
ADC0LTL
0xC5
ADC0 Less-Than Compare Word Low
AMX0N
0xBA
AMUX0 Negative Channel Select
AMX0P
0xBB
AMUX0 Positive Channel Select
B
0xF0
B Register
CKCON
0x8E
Clock Control
CLKSEL
0xA9
Clock Select
CPT0CN
0x9B
Comparator0 Control
CPT0MD
0x9D
Comparator0 Mode Selection
CPT0MX
0x9F
Comparator0 MUX Selection
CPT1CN
0x9A
Comparator1 Control
CPT1MD
0x9C
Comparator1 Mode Selection
CPT1MX
0x9E
Comparator1 MUX Selection
DPH
0x83
Data Pointer High
DPL
0x82
Data Pointer Low
EIE1
0xE6
Extended Interrupt Enable 1
EIP1
0xF6
Extended Interrupt Priority 1
EMI0CN
0xAA
External Memory Interface Control
FLKEY
0xB7
Flash Lock and Key
FLSCL
0xB6
Flash Scale
IE
0xA8
Interrupt Enable
IP
0xB8
Interrupt Priority
IT01CF
0xE4
INT0/INT1 Configuration
OSCICL
0xB3
Internal Oscillator Calibration
OSCICN
0xB2
Internal Oscillator Control
OSCXCN
0xB1
External Oscillator Control
P0
0x80
Port 0 Latch
P0MDIN
0xF1
Port 0 Input Mode Configuration
P0MDOUT
0xA4
Port 0 Output Mode Configuration
P0SKIP
0xD4
Port 0 Skip
P1
0x90
Port 1 Latch
P1MDIN
0xF2
Port 1 Input Mode Configuration
P1MDOUT
0xA5
Port 1 Output Mode Configuration
P1SKIP
0xD5
Port 1 Skip
P2
0xA0
Port 2 Latch
P2MDIN
0xF3
Port 2 Input Mode Configuration
P2MDOUT
0xA6
Port 2 Output Mode Configuration
88
Rev. 1.8
Page
92
59
60
61
61
59
59
62
62
58
57
93
193
123
72
74
73
75
77
76
91
90
99
100
119
117
117
97
98
101
122
122
125
136
136
137
137
138
138
139
139
140
140
141
C8051F310/1/2/3/4/5/6/7
Table 8.3. Special Function Registers (Continued)
Register
P2SKIP
P3
P3MDIN
P3MDOUT
PCA0CN
PCA0CPH0
PCA0CPH1
PCA0CPH2
PCA0CPH3
PCA0CPH4
PCA0CPL0
PCA0CPL1
PCA0CPL2
PCA0CPL3
PCA0CPL4
PCA0CPM0
PCA0CPM1
PCA0CPM2
PCA0CPM3
PCA0CPM4
PCA0H
PCA0L
PCA0MD
PCON
PSCTL
PSW
REF0CN
RSTSRC
SBUF0
SCON0
SMB0CF
SMB0CN
SMB0DAT
SP
SPI0CFG
SPI0CKR
SPI0CN
SPI0DAT
TCON
TH0
TH1
TL0
TL1
TMOD
TMR2CN
TMR2H
Address
0xD6
0xB0
0xF4
0xA7
0xD8
0xFC
0xEA
0xEC
0xEE
0xFE
0xFB
0xE9
0xEB
0xED
0xFD
0xDA
0xDB
0xDC
0xDD
0xDE
0xFA
0xF9
0xD9
0x87
0x8F
0xD0
0xD1
0xEF
0x99
0x98
0xC1
0xC0
0xC2
0x81
0xA1
0xA2
0xF8
0xA3
0x88
0x8C
0x8D
0x8A
0x8B
0x89
0xC8
0xCD
Description
Port 2 Skip
Port 3 Latch
Port 3 Input Mode Configuration
Port 3 Output Mode Configuration
PCA Control
PCA Capture 0 High
PCA Capture 1 High
PCA Capture 2 High
PCA Capture 3High
PCA Capture 4 High
PCA Capture 0 Low
PCA Capture 1 Low
PCA Capture 2 Low
PCA Capture 3Low
PCA Capture 4 Low
PCA Module 0 Mode
PCA Module 1 Mode
PCA Module 2 Mode
PCA Module 3 Mode
PCA Module 4 Mode
PCA Counter High
PCA Counter Low
PCA Mode
Power Control
Program Store R/W Control
Program Status Word
Voltage Reference Control
Reset Source Configuration/Status
UART0 Data Buffer
UART0 Control
SMBus Configuration
SMBus Control
SMBus Data
Stack Pointer
SPI Configuration
SPI Clock Rate Control
SPI Control
SPI Data
Timer/Counter Control
Timer/Counter 0 High
Timer/Counter 1 High
Timer/Counter 0 Low
Timer/Counter 1 Low
Timer/Counter Mode
Timer/Counter 2 Control
Timer/Counter 2 High
Rev. 1.8
Page
141
142
142
143
215
219
219
219
219
219
218
218
218
218
218
217
217
217
217
217
218
218
216
103
116
92
68
109
169
168
152
154
156
91
180
182
181
182
191
194
194
194
194
192
197
198
89
C8051F310/1/2/3/4/5/6/7
Table 8.3. Special Function Registers (Continued)
Register
Address
TMR2L
0xCC
TMR2RLH
0xCB
TMR2RLL
0xCA
TMR3CN
0x91
TMR3H
0x95
TMR3L
0x94
TMR3RLH
0x93
TMR3RLL
0x92
VDM0CN
0xFF
XBR1
0xE2
XBR0
0xE1
0x84-0x86, 0x96-0x97,
0xAB-0xAF, 0xB4, 0xB9,
0xBF, 0xC7, 0xC9, 0xCE,
0xCF, 0xD2, 0xD3, 0xD7,
0xDF, 0xE3, 0xE5, 0xF5
Description
Timer/Counter 2 Low
Timer/Counter 2 Reload High
Timer/Counter 2 Reload Low
Timer/Counter 3Control
Timer/Counter 3 High
Timer/Counter 3Low
Timer/Counter 3 Reload High
Timer/Counter 3 Reload Low
VDD Monitor Control
Port I/O Crossbar Control 1
Port I/O Crossbar Control 0
Page
198
198
198
201
202
202
202
202
107
135
134
Reserved
8.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic 1. Future product versions may use these bits to implement new features in
which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sections of the data sheet associated with their corresponding system function.
SFR Definition 8.1. DPL: Data Pointer Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x82
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed Flash memory.
90
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 8.2. DPH: Data Pointer High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0x83
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed Flash memory.
SFR Definition 8.3. SP: Stack Pointer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000111
0x81
Bits7–0: SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
Rev. 1.8
91
C8051F310/1/2/3/4/5/6/7
SFR Definition 8.4. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
CY
Bit7
R/W
R
AC
F0
RS1
RS0
Bit6
Bit5
Bit4
Bit3
OV
F1
PARITY
00000000
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xD0
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to logic 0 by all other arithmetic operations.
Bit6:
AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to logic 0 by all other arithmetic operations.
Bit5:
F0: User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
0
0
1
1
Bit2:
Bit1:
Bit0:
RS0
0
1
0
1
Register Bank
0
1
2
3
Address
0x00–0x07
0x08–0x0F
0x10–0x17
0x18–0x1F
OV: Overflow Flag.
This bit is set to 1 under the following circumstances: an ADD, ADDC, or SUBB instruction
causes a sign-change overflow, a MUL instruction results in an overflow (result is greater
than 255), or a DIV instruction causes a divide-by-zero condition. The OV bit is cleared to 0
by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other cases.
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY: Parity Flag.
This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared if the
sum is even.
SFR Definition 8.5. ACC: Accumulator
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ACC.7
ACC.6
ACC.5
ACC.4
ACC.3
ACC.2
ACC.1
ACC.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
92
Rev. 1.8
0xE0
C8051F310/1/2/3/4/5/6/7
SFR Definition 8.6. B: B Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
B.7
B.6
B.5
B.4
B.3
B.2
B.1
B.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xF0
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
8.3.
Interrupt Handler
The CIP-51 includes an extended interrupt system supporting a total of 14 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies
according to the specific version of the device. Each interrupt source has one or more associated interruptpending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition,
the associated interrupt-pending flag is set to logic 1.
If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE-EIE1). However, interrupts must first be globally enabled by setting the EA bit
(IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables
all interrupt sources regardless of the individual interrupt-enable settings.
Note: Any instruction that clears the EA bit should be immediately followed by an instruction that
has two or more opcode bytes. For example:
// in 'C':
EA = 0;
// clear EA bit
EA = 0;
// ... followed by another 2-byte opcode
; in assembly:
CLR EA
; clear EA bit
CLR EA
; ... followed by another 2-byte opcode
If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears
the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. However, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is
followed by a multi-cycle instruction, the interrupt will not be taken.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
Rev. 1.8
93
C8051F310/1/2/3/4/5/6/7
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
8.3.1. MCU Interrupt Sources and Vectors
The MCUs support 14 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU
will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 8.4 on page 96. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
94
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
8.3.2. External Interrupts
The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT1 bits in TCON (Section “17.1. Timer 0 and Timer 1” on page 187) select level
or edge sensitive. The table below lists the possible configurations.
IT0
1
1
0
0
IN0PL
0
1
0
1
/INT0 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
IT1
1
1
0
0
IN1PL
0
1
0
1
/INT1 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
/INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 8.11).
Note that /INT0 and /INT0 Port pin assignments are independent of any Crossbar assignments. /INT0 and
/INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin
via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the
selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section
“13.1. Priority Crossbar Decoder” on page 131 for complete details on configuring the Crossbar).
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the /INT0 and /INT1 external
interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR.
When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as
defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It
must then deactivate the interrupt request before execution of the ISR completes or another interrupt
request will be generated.
8.3.3. Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure
its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 8.4.
8.3.4. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5
system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no
other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
Rev. 1.8
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C8051F310/1/2/3/4/5/6/7
Bit addressable?
Cleared by HW?
Table 8.4. Interrupt Summary
N/A
N/A
IE0 (TCON.1)
TF0 (TCON.5)
IE1 (TCON.3)
TF1 (TCON.7)
RI0 (SCON0.0)
TI0 (SCON0.1)
TF2H (TMR2CN.7)
TF2L (TMR2CN.6)
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN
(SPI0CN.4)
Y
Y
Y
Y
Y
Y
Y
Y
Always
Enabled
EX0 (IE.0)
ET0 (IE.1)
EX1 (IE.2)
ET1 (IE.3)
Y
N
ES0 (IE.4) PS0 (IP.4)
Y
N
ET2 (IE.5) PT2 (IP.5)
Y
N
ESPI0
(IE.6)
7
SI (SMB0CN.0)
Y
0x0043
8
0x004B
9
0x0053
10
0x005B
11
Comparator0
0x0063
12
Comparator1
0x006B
13
Timer 3 Overflow
0x0073
14
N/A
AD0WINT
(ADC0CN.3)
AD0INT
(ADC0CN.5)
CF (PCA0CN.7)
CCFn (PCA0CN.n)
CP0FIF
(CPT0CN.4)
CP0RIF
(CPT0CN.5)
CP1FIF
(CPT1CN.4)
CP1RIF
(CPT1CN.5)
TF3H (TMR3CN.7)
TF3L (TMR3CN.6)
Interrupt Source
Interrupt Priority
Pending Flag
Vector
Order
Reset
0x0000
Top
External Interrupt 0 (/INT0)
Timer 0 Overflow
External Interrupt 1 (/INT1)
Timer 1 Overflow
0x0003
0x000B
0x0013
0x001B
0
1
2
3
UART0
0x0023
4
Timer 2 Overflow
0x002B
5
SPI0
0x0033
6
SMB0
0x003B
RESERVED
ADC0 Window Compare
ADC0 Conversion
Complete
Programmable Counter
Array
96
None
Rev. 1.8
N/A
Y
Y
Y
Enable
Flag
Priority
Control
Always
Highest
PX0 (IP.0)
PT0 (IP.1)
PX1 (IP.2)
PT1 (IP.3)
ESMB0
(EIE1.0)
N/A N/A
EWADC0
N
(EIE1.2)
EADC0
N
(EIE1.3)
EPCA0
N
(EIE1.4)
N
PSPI0
(IP.6)
PSMB0
(EIP1.0)
N/A
PWADC0
(EIP1.2)
PADC0
(EIP1.3)
PPCA0
(EIP1.4)
N
N
ECP0
(EIE1.5)
PCP0
(EIP1.5)
N
N
ECP1
(EIE1.6)
PCP1
(EIP1.6)
N
N
ET3
(EIE1.7)
PT3
(EIP1.7)
C8051F310/1/2/3/4/5/6/7
8.3.5. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the
data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
SFR Definition 8.7. IE: Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EA
ESPI0
ET2
ES0
ET1
EX1
ET0
EX0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
0xA8
EA: Enable All Interrupts.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrupts.
1: Enable interrupt requests generated by SPI0.
ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt requests generated by the TF2L or TF2H flags.
ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable external interrupt 1.
1: Enable interrupt requests generated by the /INT1 input.
ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable external interrupt 0.
1: Enable interrupt requests generated by the /INT0 input.
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SFR Definition 8.8. IP: Interrupt Priority
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
PSPI0
PT2
PS0
PT1
PX1
PT0
PX0
10000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
98
UNUSED. Read = 1, Write = don't care.
PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupts set to low priority level.
1: Timer 2 interrupts set to high priority level.
PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupts set to low priority level.
1: UART0 interrupts set to high priority level.
PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupts set to low priority level.
1: Timer 1 interrupts set to high priority level.
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
Rev. 1.8
0xB8
C8051F310/1/2/3/4/5/6/7
SFR Definition 8.9. EIE1: Extended Interrupt Enable 1
R/W
R/W
R/W
R/W
R/W
ET3
ECP1
ECP0
EPCA0
EADC0
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
EWADC0 Reserved
Bit2
Bit1
R/W
Reset Value
ESMB0
00000000
Bit0
SFR Address:
0xE6
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt requests generated by the TF3L or TF3H flags.
ECP1: Enable Comparator1 (CP1) Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 interrupts.
1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags.
ECP0: Enable Comparator0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags.
EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
EADC0: Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT).
RESERVED. Read = 0. Must Write 0.
ESMB0: Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
Rev. 1.8
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C8051F310/1/2/3/4/5/6/7
SFR Definition 8.10. EIP1: Extended Interrupt Priority 1
R/W
R/W
R/W
R/W
R/W
PT3
PCP1
PCP0
PCP0
PADC0
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
PWADC0 Reserved
Bit2
R/W
Reset Value
PSMB0
00000000
Bit0
SFR Address:
Bit1
0xF6
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
100
PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
PCP1: Comparator1 (CP1) Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 interrupt set to low priority level.
1: CP1 interrupt set to high priority level.
PCP0: Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority level.
1: PCA0 interrupt set to high priority level.
PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
PWADC0: ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority level.
1: ADC0 Window interrupt set to high priority level.
RESERVED. Read = 0. Must Write 0.
PSMB0: SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 8.11. IT01CF: INT0/INT1 Configuration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
IN1PL
IN1SL2
IN1SL1
IN1SL0
IN0PL
IN0SL2
IN0SL1
IN0SL0
00000001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE4
Note: Refer to SFR Definition 17.1 for INT0/1 edge- or level-sensitive interrupt selection.
Bit7:
IN1PL: /INT1 Polarity
0: /INT1 input is active low.
1: /INT1 input is active high.
Bits6–4: IN1SL2–0: /INT1 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT1. Note that this pin assignment is independent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
IN1SL2–0
000
001
010
011
100
101
110
111
/INT1 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Bit3:
IN0PL: /INT0 Polarity
0: /INT0 interrupt is active low.
1: /INT0 interrupt is active high.
Bits2–0: INT0SL2–0: /INT0 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT0. Note that this pin assignment is independent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
IN0SL2–0
000
001
010
011
100
101
110
111
/INT0 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Rev. 1.8
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8.4.
Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped
(analog peripherals remain in their selected states; the external oscillator is not effected). Since clocks are
running in Idle mode, power consumption is dependent upon the system clock frequency and the number
of peripherals left in active mode before entering Idle. Stop mode consumes the least power. SFR Definition 8.12 describes the Power Control Register (PCON) used to control the CIP-51's power management
modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital
peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off the oscillators lowers power consumption considerably; however, a reset is required to restart the MCU.
8.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes execution. All internal registers and memory maintain their
original data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event
of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by
software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. Refer to Section “9.6. PCA Watchdog
Timer Reset” on page 108 for more information on the use and configuration of the WDT.
Note: Any instruction that sets the IDLE bit should be immediately followed by an instruction that
has 2 or more opcode bytes. For example:
// in 'C':
PCON |= 0x01; // set IDLE bit
PCON = PCON; // ... followed by a 3-cycle dummy instruction
; in assembly:
ORL PCON, #01h ; set IDLE bit
MOV PCON, PCON; ... followed by a 3-cycle dummy instruction
If the instruction following the write of the IDLE bit is a single-byte instruction and an interrupt occurs during
the execution phase of the instruction that sets the IDLE bit, the CPU may not wake from IDLE mode when
a future interrupt occurs.
102
Rev. 1.8
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8.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including
the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can
only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset
sequence and begins program execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the
MCD timeout of 100 µsec.
SFR Definition 8.12. PCON: Power Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GF5
GF4
GF3
GF2
GF1
GF0
STOP
IDLE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x87
Bits7–2: GF5–GF0: General Purpose Flags 5–0.
These are general purpose flags for use under software control.
Bit1:
STOP: Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
1: CPU goes into Stop mode (internal oscillator stopped).
Bit0:
IDLE: Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial
Ports, and Analog Peripherals are still active.)
Rev. 1.8
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NOTES:
104
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
9.
Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
•
•
•
•
CIP-51 halts program execution
Special Function Registers (SFRs) are initialized to their defined reset values
External Port pins are forced to a known state
Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled
during and after the reset. For VDD Monitor and power-on resets, the RST pin is driven low until the device
exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section “12. Oscillators” on page 121 for information on selecting and configuring
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “18.3. Watchdog Timer Mode” on page 212 details the use of the Watchdog Timer).
Program execution begins at location 0x0000.
VDD
Power On
Reset
Supply
Monitor
'0'
Enable
(wired-OR)
/RST
+
C0RSEF
Missing
Clock
Detector
(oneshot)
EN
Reset
Funnel
PCA
WDT
(Software Reset)
SWRSF
Errant
FLASH
Operation
EN
System
Clock
WDT
Enable
Px.x
+
-
Comparator 0
MCD
Enable
Px.x
CIP-51
Microcontroller
Core
System Reset
Extended Interrupt
Handler
Figure 9.1. Reset Sources
Rev. 1.8
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9.1.
Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low until VDD settles above
VRST. An additional delay occurs before the device is released from reset; the delay decreases as the VDD
ramp time increases (VDD ramp time is defined as how fast VDD ramps from 0 V to VRST). Figure 9.2. plots
the power-on and VDD monitor reset timing. For valid ramp times (less than 1 ms), the power-on reset
delay (TPORDelay) is typically less than 0.3 ms.
Note: The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to be released from
reset before VDD reaches the VRST level.
volts
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data memory should be assumed to be undefined after a power-on reset. The VDD monitor is disabled following a
power-on reset.
VDD
2.70
2.55
VRST
VD
D
2.0
1.0
t
Logic HIGH
Logic LOW
/RST
TPORDelay
VDD
Monitor
Reset
Power-On
Reset
Figure 9.2. Power-On and VDD Monitor Reset Timing
9.2.
Power-Fail Reset / VDD Monitor
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply
monitor will drive the RST pin low and hold the CIP-51 in a reset state (see Figure 9.2). When VDD returns
to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data
memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below
the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be valid. The VDD
monitor is disabled after power-on resets; however its defined state (enabled/disabled) is not altered by
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any other reset source. For example, if the VDD monitor is enabled and a software reset is performed, the
VDD monitor will still be enabled after the reset.
Important Note: The VDD monitor must be enabled before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it is enabled and stabilized may cause a system reset. The procedure for configuring the VDD monitor as a reset source is shown below:
Step 1. Enable the VDD monitor (VDMEN bit in VDM0CN = ‘1’).
Step 2. Wait for the VDD monitor to stabilize (see Table 9.1 for the VDD Monitor turn-on time).
Note: This delay should be omitted if software contains routines that erase or write Flash
memory.
Step 3. Select the VDD monitor as a reset source (PORSF bit in RSTSRC = ‘1’).
See Figure 9.2 for VDD monitor timing; note that the reset delay is not incurred after a VDD monitor reset.
See Table 9.1 for complete electrical characteristics of the VDD monitor.
SFR Definition 9.1. VDM0CN: VDD Monitor Control
R/W
R
R
R
R
R
R
R
VDMEN VDDSTAT Reserved Reserved Reserved Reserved Reserved Reserved
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Reset Value
Variable
Bit0
SFR Address: 0xFF
Bit7:
VDMEN: VDD Monitor Enable.
This bit is turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system
resets until it is also selected as a reset source in register RSTSRC (Figure 9.2). The VDD
Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it has stabilized may generate a system reset.
See Table 9.1 for the minimum VDD Monitor turn-on time.
0: VDD Monitor Disabled.
1: VDD Monitor Enabled.
Bit6:
VDD STAT: VDD Status.
This bit indicates the current power supply status (VDD Monitor output).
0: VDD is at or below the VDD monitor threshold.
1: VDD is above the VDD monitor threshold.
Bits5–0: Reserved. Read = Variable. Write = don’t care.
9.3.
External Reset
The external RST pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the RST pin generates a reset; an external pullup and/or decoupling of the RST
pin may be necessary to avoid erroneous noise-induced resets. See Table 9.1 for complete RST pin specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
Rev. 1.8
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9.4.
Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system
clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a
MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise,
this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables
it. The state of the RST pin is unaffected by this reset.
9.5.
Comparator0 Reset
Comparator0 can be configured as a reset source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter
on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting
input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset
state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the
reset source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset.
9.6.
PCA Watchdog Timer Reset
The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be
used to prevent software from running out of control during a system malfunction. The PCA WDT function
can be enabled or disabled by software as described in Section “18.3. Watchdog Timer Mode” on
page 212; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction
prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is
set to ‘1’. The state of the RST pin is unaffected by this reset.
9.7.
Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
•
•
•
•
A Flash write or erase is attempted above user code space. This occurs when PSWE is set to ‘1’ and a
MOVX write operation targets an address above address 0x3DFF for C8051F310/1 or 0x1FFF for
C8051F312/3/4/5.
A Flash read is attempted above user code space. This occurs when a MOVC operation targets an
address above address 0x3DFF for C8051F310/1 or 0x1FFF for C8051F312/3/4/5.
A Program read is attempted above user code space. This occurs when user code attempts to branch
to an address above 0x3DFF for C8051F310/1 or 0x1FFF for C8051F312/3/4/5.
A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section
“10.3. Security Options” on page 113).
The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by
this reset.
9.8.
Software Reset
Software may force a reset by writing a ‘1’ to the SWRSF bit (RSTSRC.4). The SWRSF bit will read ‘1’ following a software forced reset. The state of the RST pin is unaffected by this reset.
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SFR Definition 9.2. RSTSRC: Reset Source
R
Bit7
R
R/W
FERROR C0RSEF
Bit6
Bit5
R/W
SWRSF
Bit4
R
R/W
WDTRSF MCDRSF
Bit3
Bit2
R/W
R
Reset Value
PORSF
PINRSF
Variable
Bit1
Bit0
SFR Address: 0xEF
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Note:
UNUSED. Read = 0. Write = don’t care.
FERROR: Flash Error Indicator.
0: Source of last reset was not a Flash read/write/erase error.
1: Source of last reset was a Flash read/write/erase error.
C0RSEF: Comparator0 Reset Enable and Flag.
0: Read: Source of last reset was not Comparator0. Write: Comparator0 is not a reset
source.
1: Read: Source of last reset was Comparator0. Write: Comparator0 is a reset source
(active-low).
SWRSF: Software Reset Force and Flag.
0: Read: Source of last reset was not a write to the SWRSF bit. Write: No Effect.
1: Read: Source of last was a write to the SWRSF bit. Write: Forces a system reset.
WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
MCDRSF: Missing Clock Detector Flag.
0: Read: Source of last reset was not a Missing Clock Detector timeout. Write: Missing
Clock Detector disabled.
1: Read: Source of last reset was a Missing Clock Detector timeout. Write: Missing Clock
Detector enabled; triggers a reset if a missing clock condition is detected.
PORSF: Power-On Reset Force and Flag.
This bit is set anytime a power-on reset occurs. Writing this bit enables/disables the VDD
monitor as a reset source. Note: writing ‘1’ to this bit before the VDD monitor is enabled
and stabilized may cause a system reset. See register VDM0CN (Figure 9.1)
0: Read: Last reset was not a power-on or VDD monitor reset. Write: VDD monitor is not a
reset source.
1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate.
Write: VDD monitor is a reset source.
PINRSF: HW Pin Reset Flag.
0: Source of last reset was not RST pin.
1: Source of last reset was RST pin.
For bits that act as both reset source enables (on a write) and reset indicator flags (on a read),
read-modify-write instructions read and modify the source enable only. This applies to bits:
C0RSEF, SWRSF, MCDRSF, PORSF.
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Table 9.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Min
Typ
Max
Units
—
—
0.6
V
RST Input High Voltage
0.7 x
VDD
—
—
V
RST Input Low Voltage
—
—
0.3 x
VDD
—
25
40
µA
2.40
2.55
2.70
V
RST Output Low Voltage
RST Input Pullup Current
Conditions
IOL = 8.5 mA, VDD = 2.7 to 3.6 V
RST = 0.0 V
VDD Monitor Threshold (VRST)
Missing Clock Detector Timeout
Time from last system clock rising
edge to reset initiation
100
220
600
µs
Reset Time Delay
Delay between release of any
reset source and code execution
at location 0x0000
5.0
—
—
µs
Minimum RST Low Time to
Generate a System Reset
15
—
—
µs
VDD Monitor Turn-on Time
100
—
—
µs
—
20
50
µA
—
—
1
ms
VDD Monitor Supply Current
VDD Ramp Time
110
VDD = 0 V to VDD = 2.7 V
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
10. Flash Memory
On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The
Flash memory can be programmed in-system, a single byte at a time, through the C2 interface or by software using the MOVX instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic
1. Flash bytes would typically be erased (set to 0xFF) before being reprogrammed. The write and erase
operations are automatically timed by hardware for proper execution; data polling to determine the end of
the write/erase operation is not required. Code execution is stalled during a Flash write/erase operation.
Refer to Table 10.1 for complete Flash memory electrical characteristics.
10.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initialized device. For details on the C2 commands to program Flash memory, see Section “20. C2 Interface”
on page 223.
To ensure the integrity of Flash contents, it is strongly recommended that the on-chip VDD Monitor
be enabled in any system that includes code that writes and/or erases Flash memory from software.
10.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be performed. The FLKEY register is detailed in SFR Definition 10.2.
10.1.2. Flash Erase Procedure
The Flash memory can be programmed from software using the MOVX write instruction with the address
and data byte to be programmed provided as normal operands. Before writing to Flash memory using
MOVX, Flash write operations must be enabled by: (1) setting the PSWE Program Store Write Enable bit
(PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the Flash key
codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared by software.
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written.
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Disable interrupts (recommended).
Set the PSEE bit (register PSCTL).
Set the PSWE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write a data byte to any location within the 512-byte page to
be erased.
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10.1.3. Flash Write Procedure
Flash bytes are programmed by software with the following sequence:
Step 1. Disable interrupts (recommended).
Step 2. Erase the 512-byte Flash page containing the target location, as described in Section
10.1.2.
Step 3. Set the PSWE bit (register PSCTL).
Step 4. Clear the PSEE bit (register PSCTL).
Step 5. Write the first key code to FLKEY: 0xA5.
Step 6. Write the second key code to FLKEY: 0xF1.
Step 7. Using the MOVX instruction, write a single data byte to the desired location within the
512 byte sector.
Steps 5–7 must be repeated for each byte to be written. After Flash writes are complete, PSWE should be
cleared so that MOVX instructions do not target program memory.
Table 10.1. Flash Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
C8051F310/1/6/7
16384*
Flash Size
C8051F312/3/4/5
8192
Endurance
20 k
Erase Cycle Time
25 MHz System Clock
10
Write Cycle Time
25 MHz System Clock
40
Typ
—
—
100 k
15
55
Max
—
—
—
20
70
Units
bytes
Erase/Write
ms
µs
*Note: 512 bytes at locations 0x3E00 (C8051F310/1) are reserved.
10.2. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM.
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10.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before
software can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security
mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to
0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the
page containing the Flash Security Lock Byte is unlocked when no other Flash pages are locked
(all bits of the Lock Byte are ‘1’) and locked when any other Flash pages are locked (any bit of the
Lock Byte is ‘0’). See the example below.
Security Lock Byte:
1’s Complement:
Flash pages locked:
11111101b
00000010b
3 (First two Flash pages + Lock Byte Page)
Addresses locked:
0x0000 to 0x03FF (first two Flash pages)
and 0x3C00 to 0x3DFF or 0x1E00 to 0x1FFF (Lock Byte Page)
C8051F310/1/6/7
C8051F312/3/4/5
Reserved
Reserved
0x3E00
Locked when any
other FLASH pages
are locked
Lock Byte
0x2000
Lock Byte
0x3DFF
0x1FFF
0x3DFE
0x1FFE
0x3C00
0x1E00
Unlocked FLASH Pages
FLASH memory
organized in 512-byte
pages
Unlocked FLASH Pages
Access limit set
according to the
FLASH security lock
byte
0x0000
0x0000
Figure 10.1. Flash Program Memory Map
Rev. 1.8
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The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executing on locked pages. Table 10.2 summarizes the Flash security
features of the C8051F31x devices.
Table 10.2. Flash Security Summary
Action
C2 Debug
Interface
User Firmware executing from:
an unlocked page
a locked page
Permitted
Permitted
Permitted
Not Permitted
Flash Error Reset
Permitted
Read or Write page containing Lock Byte
(if no pages are locked)
Permitted
Permitted
Permitted
Read or Write page containing Lock Byte
(if any page is locked)
Not Permitted
Flash Error Reset
Permitted
Read contents of Lock Byte
(if no pages are locked)
Permitted
Permitted
Permitted
Read contents of Lock Byte
(if any page is locked)
Not Permitted
Flash Error Reset
Permitted
Read, Write or Erase unlocked pages
(except page with Lock Byte)
Read, Write or Erase locked pages
(except page with Lock Byte)
Erase page containing Lock Byte
(if no pages are locked)
Permitted
Flash Error Reset Flash Error Reset
C2 Device
Erase Only
Flash Error Reset Flash Error Reset
Lock additional pages
(change '1's to '0's in the Lock Byte)
Not Permitted
Flash Error Reset Flash Error Reset
Unlock individual pages
(change '0's to '1's in the Lock Byte)
Not Permitted
Flash Error Reset Flash Error Reset
Read, Write or Erase Reserved Area
Not Permitted
Flash Error Reset Flash Error Reset
Erase page containing Lock Byte - Unlock all
pages (if any page is locked)
C2 Device Erase - Erases all Flash pages including the page containing the Lock Byte.
Flash Error Reset - Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after
reset).
- All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset).
- Locking any Flash page also locks the page containing the Lock Byte.
- Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase.
- If user code writes to the Lock Byte, the Lock does not take effect until the next device reset.
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10.4. Flash Write and Erase Guidelines
Any system which contains routines which write or erase Flash memory from software involves some risk
that the write or erase routines will execute unintentionally if the CPU is operating outside its specified
operating range of VDD, system clock frequency, or temperature. This accidental execution of Flash modifying code can result in alteration of Flash memory contents causing a system failure that is only recoverable by re-Flashing the code in the device.
The following guidelines are recommended for any system that contains routines which write or erase
Flash from code.
10.4.1. VDD Maintenance and the VDD Monitor
1. If the system power supply is subject to voltage or current "spikes," add sufficient transient
protection devices to the power supply to ensure that the supply voltages listed in the Absolute
Maximum Ratings table are not exceeded.
2. Make certain that the minimum VDD rise time specification of 1 ms is met. If the system cannot
meet this rise time specification, then add an external VDD brownout circuit to the RST pin of
the device that holds the device in reset until VDD reaches 2.7 V and re-asserts RST if VDD
drops below 2.7 V.
3. Enable the on-chip VDD monitor and enable the VDD monitor as a reset source as early in code
as possible. This should be the first set of instructions executed after the Reset Vector. For 'C'based systems, this will involve modifying the startup code added by the 'C' compiler. See your
compiler documentation for more details. Make certain that there are no delays in software
between enabling the VDD monitor and enabling the VDD monitor as a reset source. Code
examples showing this can be found in "AN201: Writing to Flash from Firmware", available
from the Silicon Laboratories web site.
4. As an added precaution, explicitly enable the VDD monitor and enable the VDD monitor as a
reset source inside the functions that write and erase Flash memory. The VDD monitor enable
instructions should be placed just after the instruction to set PSWE to a '1', but before the
Flash write or erase operation instruction.
5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment
operators and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC = 0x02" is correct. "RSTSRC |= 0x02" is incorrect.
6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a '1'. Areas
to check are initialization code which enables other reset sources, such as the Missing Clock
Detector or Comparator, for example, and instructions which force a Software Reset. A global
search on "RSTSRC" can quickly verify this.
10.4.2. PSWE Maintenance
7. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a '1'. There
should be exactly one routine in code that sets PSWE to a '1' to write Flash bytes and one routine in code that sets PSWE and PSEE both to a '1' to erase Flash pages.
8. Minimize the number of variable accesses while PSWE is set to a '1'. Handle pointer address
updates and loop variable maintenance outside the "PSWE = 1; ... PSWE = 0;" area. Code
examples showing this can be found in AN201, "Writing to Flash from Firmware", available
from the Silicon Laboratories web site.
9. Disable interrupts prior to setting PSWE to a '1' and leave them disabled until after PSWE has
been reset to '0'. Any interrupts posted during the Flash write or erase operation will be serviced in priority order after the Flash operation has been completed and interrupts have been
re-enabled by software.
Rev. 1.8
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10. Make certain that the Flash write and erase pointer variables are not located in XRAM. See
your compiler documentation for instructions regarding how to explicitly locate variables in different memory areas.
11. Add address bounds checking to the routines that write or erase Flash memory to ensure that
a routine called with an illegal address does not result in modification of the Flash.
10.4.3. System Clock
12. If operating from an external crystal, be advised that crystal performance is susceptible to
electrical interference and is sensitive to layout and to changes in temperature. If the system is
operating in an electrically noisy environment, use the internal oscillator or use an external
CMOS clock.
13. If operating from the external oscillator, switch to the internal oscillator during Flash write or
erase operations. The external oscillator can continue to run, and the CPU can switch back to
the external oscillator after the Flash operation has completed.
Additional Flash recommendations and example code can be found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site.
SFR Definition 10.1. PSCTL: Program Store R/W Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
-
PSEE
PSWE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8F
Bits7–2: UNUSED: Read = 000000b, Write = don’t care.
Bit1:
PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memory
to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
Bit0:
PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash program memory disabled.
1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash
memory.
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SFR Definition 10.2. FLKEY: Flash Lock and Key
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB7
Bits7–0: FLKEY: Flash Lock and Key Register
Write:
This register must be written to before Flash writes or erases can be performed. Flash
remains locked until this register is written to with the following key codes: 0xA5, 0xF1. The
timing of the writes does not matter, as long as the codes are written in order. The key codes
must be written for each Flash write or erase operation. Flash will be locked until the next
system reset if the wrong codes are written or if a Flash operation is attempted before the
codes have been written correctly.
Read:
When read, bits 1-0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash writes/erases disabled until the next reset.
SFR Definition 10.3. FLSCL: Flash Scale
R/W
FOSE
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Reserved Reserved Reserved Reserved Reserved Reserved Reserved 10000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB6
Bits7:
FOSE: Flash One-shot Enable
This bit enables the Flash read one-shot. When the Flash one-shot disabled, the Flash
sense amps are enabled for a full clock cycle during Flash reads. At system clock frequencies below 10 MHz, disabling the Flash one-shot will increase system power consumption.
0: Flash one-shot disabled.
1: Flash one-shot enabled.
Bits6–0: RESERVED. Read = 0. Must Write 0.
Rev. 1.8
117
C8051F310/1/2/3/4/5/6/7
NOTES:
118
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
11. External RAM
The C8051F31x devices include 1024 bytes of RAM mapped into the external data memory space. All of
these address locations may be accessed using the external move instruction (MOVX) and the data
pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit
address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in SFR Definition 11.1). Note: the MOVX instruction is
also used for writes to the Flash memory. See Section “10. Flash Memory” on page 111 for details. The
MOVX instruction accesses XRAM by default.
For a 16-bit MOVX operation (@DPTR), the upper 6-bits of the 16-bit external data memory address word
are "don't cares.” As a result, the 1024 byte RAM is mapped modulo style over the entire 64 k external
data memory address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses
0x0400, 0x0800, 0x0C00, 0x1000, etc. This is a useful feature when performing a linear memory fill, as the
address pointer doesn't have to be reset when reaching the RAM block boundary.
SFR Definition 11.1. EMI0CN: External Memory Interface Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
PGSEL
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xAA
Bits 7–2: UNUSED. Read = 000000b. Write = don’t care.
Bits 1–0: PGSEL: XRAM Page Select.
The EMI0CN register provides the high byte of the 16-bit external data memory address
when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. Since
the upper (unused) bits of the register are always zero, the PGSEL determines which page
of XRAM is accessed.
For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed.
Rev. 1.8
119
C8051F310/1/2/3/4/5/6/7
NOTES:
120
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
12. Oscillators
C8051F31x devices include a programmable internal oscillator and an external oscillator drive circuit. The
internal oscillator can be enabled/disabled and calibrated using the OSCICN and OSCICL registers, as
shown in Figure 12.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or a scaled version of the internal oscillator. The internal oscillator's electrical specifications are given
in Table 12.1 on page 123.
XTAL2
EN
Option 4
XTAL2
Option 2
VDD
CLKSL0
Option 3
CLKSEL
IFCN1
IFCN0
OSCICN
IOSCEN
IFRDY
OSCICL
Programmable
Internal Clock
Generator
n
SYSCLK
Option 1
XTAL1
Input
Circuit
10M
XTAL2
OSC
XFCN2
XFCN1
XFCN0
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
XTAL2
OSCXCN
Figure 12.1. Oscillator Diagram
12.1. Programmable Internal Oscillator
All C8051F31x devices include a programmable internal oscillator that defaults as the system clock after a
system reset. The internal oscillator period can be programmed via the OSCICL register as defined by
SFR Definition 12.1 OSCICL is factor calibrated to obtain a 24.5 MHz frequency.
Electrical specifications for the precision internal oscillator are given in Table 12.1 on page 123. Note that
the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as
defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
Rev. 1.8
121
C8051F310/1/2/3/4/5/6/7
SFR Definition 12.1. OSCICL: Internal Oscillator Calibration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
Variable
0xB3
Bit7:
UNUSED. Read = 0. Write = don’t care.
Bits 6–0: OSCICL: Internal Oscillator Calibration Register.
This register determines the internal oscillator period. This reset value for OSCICL determines the oscillator base frequency. The reset value is factory calibrated to generate an
internal oscillator frequency of 24.5 MHz.
SFR Definition 12.2. OSCICN: Internal Oscillator Control
R/W
R
IOSCEN
IFRDY
Bit7
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
R/W
R/W
Reset Value
IFCN1
IFCN0
11000000
Bit1
Bit0
SFR Address:
Bit2
0xB2
Bit7:
IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit6:
IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator is not running at programmed frequency.
1: Internal Oscillator is running at programmed frequency.
Bits5–2: UNUSED. Read = 0000b, Write = don't care.
Bits1–0: IFCN1-0: Internal Oscillator Frequency Control Bits.
00: SYSCLK derived from Internal Oscillator divided by 8.
01: SYSCLK derived from Internal Oscillator divided by 4.
10: SYSCLK derived from Internal Oscillator divided by 2.
11: SYSCLK derived from Internal Oscillator divided by 1.
122
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 12.3. CLKSEL: Clock Select
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reserved Reserved Reserved Reserved Reserved Reserved Reserved
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Reset Value
CLKSL0
00000000
Bit0
SFR Address:
Bit1
0xA9
Bits7–1: Reserved. Read = 0000000b, Must Write = 0000000.
Bit0:
CLKSL0: System Clock Source Select Bit.
0: SYSCLK derived from the Internal Oscillator, and scales per the IFCN bits in register
OSCICN.
1: SYSCLK derived from the External Oscillator circuit.
Table 12.1. Internal Oscillator Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Internal Oscillator Frequency
Internal Oscillator Supply
OSCICN.7 = 1
Current (from VDD)
Rev. 1.8
Min
24
Typ
24.5
Max
25
Units
MHz
—
450
1000
µA
123
C8051F310/1/2/3/4/5/6/7
12.2. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 12.1. A
10 Mresistor also must be wired across the XTAL2 and XTAL1 pins for the crystal/resonator configuration. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as
shown in Option 2, 3, or 4 of Figure 12.1. The type of external oscillator must be selected in the OSCXCN
register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 12.4).
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is
enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar
should be configured to skip the Port pins used by the oscillator circuit; see Section “13.1. Priority Crossbar Decoder” on page 131 for Crossbar configuration. Additionally, when using the external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog
inputs. In CMOS clock mode, the associated pin should be configured as a digital input. See Section
“13.2. Port I/O Initialization” on page 133 for details on Port input mode selection.
12.3. System Clock Selection
The CLKSL0 bit in register CLKSEL selects which oscillator is used as the system clock. CLKSL0 must be
set to ‘1’ for the system clock to run from the external oscillator; however the external oscillator may still
clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The
system clock may be switched on-the-fly between the internal and external oscillator, so long as the
selected oscillator is enabled and has settled. The internal oscillator requires little start-up time and may be
selected as the system clock immediately following the OSCICN write that enables the internal oscillator.
External crystals and ceramic resonators typically require a start-up time before they are settled and ready
for use as the system clock. The Crystal Valid Flag (XTLVLD in register OSCXCN) is set to ‘1’ by hardware
when the external oscillator is settled. To avoid reading a false XTLVLD, in crystal mode software
should delay at least 1 ms between enabling the external oscillator and checking XTLVLD. RC and
C modes typically require no startup time.
124
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 12.4. OSCXCN: External Oscillator Control
R
R/W
R/W
R/W
R
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
Reset Value
XFCN2
XFCN1
XFCN0
00000000
Bit2
Bit1
Bit0
SFR Address:
Bit3
0xB1
Bit7:
XTLVLD: Crystal Oscillator Valid Flag.
(Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2-0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3:
RESERVED. Read = 0, Write = don't care.
Bits2–0: XFCN2-0: External Oscillator Frequency Control Bits.
000-111: See table below:
XFCN
000
001
010
011
100
101
110
111
Crystal (XOSCMD = 11x)
f 32 kHz
32 kHz f 84 kHz
84 kHz f 225 kHz
225 kHz f 590 kHz
590 kHz f 1.5 MHz
1.5 MHz f 4 MHz
4 MHz f 10 MHz
10 MHz f 30 MHz
RC (XOSCMD = 10x)
f 25 kHz
25 kHz f 50 kHz
50 kHz f 100 kHz
100 kHz f 200 kHz
200 kHz f 400 kHz
400 kHz f 800 kHz
800 kHz f 1.6 MHz
1.6 MHz f 3.2 MHz
C (XOSCMD = 10x)
K Factor = 0.87
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
K Factor = 180
K Factor = 664
K Factor = 1590
CRYSTAL MODE (Circuit from Figure 12.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal frequency.
RC MODE (Circuit from Figure 12.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
f = 1.23(103) / (R x C), where
f = frequency of clock in MHz
C = capacitor value in pF
R = Pullup resistor value in k
C MODE (Circuit from Figure 12.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x VDD), where
f = frequency of clock in MHz
C = capacitor value the XTAL2 pin in pF
VDD = Power Supply on MCU in volts
Rev. 1.8
125
C8051F310/1/2/3/4/5/6/7
12.4. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 12.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 12.4. For example, an
11.0592 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Force the XTAL1 and XTAL2 pins low by writing 0s to the port latch.
Configure XTAL1 and XTAL2 as analog inputs.
Enable the external oscillator.
Wait at least 1 ms.
Poll for XTLVLD => '1'.
Switch the system clock to the external oscillator.
Note: Tuning-fork crystals may require additional settling time before XTLVLD returns a valid result.
The capacitors shown in the external crystal configuration provide the load capacitance required by the
crystal for correct oscillation. These capacitors are "in series" as seen by the crystal and "in parallel" with
the stray capacitance of the XTAL1 and XTAL2 pins.
Note: The load capacitance depends upon the crystal and the manufacturer. Please refer to the crystal
data sheet when completing these calculations.
For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should
use the configuration shown in Figure 12.1, Option 1. The total value of the capacitors and the stray capacitance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors
yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 12.2.
22 pF
XTAL1
10 M
32.768 kHz
XTAL2
22 pF
Figure 12.2. 32.768 kHz External Crystal Example
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
126
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
12.5. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 12.1, Option 2. The capacitor should be no greater than 100 pF; however, for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 k and C = 50 pF:
f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 x 50 ] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 12.4, the required XFCN setting is 010b.
12.6. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 12.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and
C = 50 pF:
f = KF / ( C x VDD ) = KF / ( 50 x 3 ) MHz
f = KF / 150 MHz
If a frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 12.4 as
KF = 22:
f = 22 / 150 = 0.146 MHz, or 146 kHz
Therefore, the XFCN value to use in this example is 011b.
Rev. 1.8
127
C8051F310/1/2/3/4/5/6/7
NOTES:
128
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
13. Port Input/Output
Digital and analog resources are available through 29 I/O pins (C8051F310/2/4), or 25 I/O pins
(C8051F311/3/5), or 21 I/O pins (C8051F316/7). Port pins are organized as three byte-wide Ports and one
5-bit-wide (C8051F310/2/4) or 1-bit-wide (C8051F311/3/5) Port. In the C8051F316/7, the port pins are
organized as one byte-wide Port, two 6-bit-wide Ports and one 1-bit-wide Port. Each of the Port pins can
be defined as general-purpose I/O (GPIO) or analog input; Port pins P0.0-P2.3 can be assigned to one of
the internal digital resources as shown in Figure 13.3. The designer has complete control over which functions are assigned, limited only by the number of physical I/O pins. This resource assignment flexibility is
achieved through the use of a Priority Crossbar Decoder. The state of a Port I/O pin can always be read in
the corresponding Port latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 13.3 and Figure 13.4). The registers XBR0 and XBR1, defined in SFR Definition 13.1 and SFR
Definition 13.2, are used to select internal digital functions.
All Port I/Os are 5 V tolerant (refer to Figure 13.2 for the Port cell circuit). The Port I/O cells are configured
as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2,3). Complete Electrical Specifications for Port I/O are given in Table 13.1 on page 143.
XBR0, XBR1,
PnSKIP Registers
PnMDOUT,
PnMDIN Registers
Priority
Decoder
Highest
Priority
UART
4
SPI
(Internal Digital Signals)
2
SMBus
8
P0
I/O
Cells
P0.0
P1
I/O
Cells
P1.0
P2
I/O
Cells
P2.0
CP0
Outputs
2
CP1
Outputs
2
Digital
Crossbar
8
4
8
SYSCLK
P3
I/O
Cells
P3.0
4
5
T0, T1
2
P2.7
P3.4
Notes:
1. P3.1-P3.4 only available on the
C8051F310/2/4
2. P1.6,P1.7,P2.6,P2.7 only available
on the C8051F310/1/2/3/4/5
8
P0
(P0.0-P0.7)
P1
(P1.0-P1.7)
8
(Port Latches)
P1.7
6
PCA
Lowest
Priority
P0.7
2
4
(P2.0-P2.3)
P2
4
(P2.4-P2.7)
5
P3
(P3.0-P3.4)
Figure 13.1. Port I/O Functional Block Diagram
Rev. 1.8
129
C8051F310/1/2/3/4/5/6/7
/WEAK-PULLUP
VDD
PUSH-PULL
/PORT-OUTENABLE
VDD
(WEAK)
PORT
PAD
PORT-OUTPUT
GND
Analog Select
ANALOG INPUT
PORT-INPUT
Figure 13.2. Port I/O Cell Block Diagram
130
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
13.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 13.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that
are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.3 and/or
P0.2 if the external oscillator circuit is enabled, P0.6 if the ADC is configured to use the external conversion
start signal (CNVSTR), and any selected ADC or Comparator inputs. The Crossbar skips selected pins as
if they were already assigned, and moves to the next unassigned pin. Figure 13.3 shows the Crossbar
Decoder priority with no Port pins skipped (P0SKIP, P1SKIP, P2SKIP = 0x00); Figure 13.4 shows the
Crossbar Decoder priority with the XTAL1 (P0.2) and XTAL2 (P0.3) pins skipped (P0SKIP = 0x0C to skip
P0.2 and P0.3 for XTAL use).
P1
XTAL1
XTAL2
3
4
5
6
7
0
1
2
0
0
0
0
0
0
0
0
VREF
2
SF Signals
PIN I/O
0
1
0
0
0
P2
CNVSTR
P0
3
4
5
6
7
0
0
0
0
0
0
0
1
2
3
0
0
0
4
5
6
7
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
Signals Unavailable
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
P0SKIP[0:7]
P1SKIP[0:7]
P2SKIP[0:3]
Port pin potentially available to peripheral
SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must
be manually configured to skip their corresponding port pins.
*Note: NSS is only pinned out in 4-wire SPI mode.
Note: P1.6,P1.7,P2.6,P2.7 only available on the C8051F310/1/2/3/4/5; P1SKIP[7:6] should always be
set to 11b for the C8051F316/7 devices.
Figure 13.3. Crossbar Priority Decoder with No Pins Skipped
Rev. 1.8
131
C8051F310/1/2/3/4/5/6/7
P1
XTAL1
XTAL2
3
4
5
6
7
0
1
2
1
0
0
0
0
0
0
0
VREF
2
SF Signals
PIN I/O
0
1
0
0
1
P2
CNVSTR
P0
3
4
5
6
7
0
0
0
0
0
0
0
1
2
3
0
0
0
4
5
6
7
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
Signals Unavailable
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
P0SKIP[0:7]
P1SKIP[0:7]
P2SKIP[0:3]
Port pin potentially available to peripheral
SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must
be manually configured to skip their corresponding port pins.
*Note: NSS is only pinned out in 4-wire SPI mode.
Note: P1.6,P1.7,P2.6,P2.7 only available on the C8051F310/1/2/3/4/5; P1SKIP[7:6] should always be set to
11b for the C8051F316/7 devices.
Figure 13.4. Crossbar Priority Decoder with Crystal Pins Skipped
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note
that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and
SCL); when the UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX).
UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART
RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized functions
have been assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the NSSMD1-NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be
routed to a Port pin.
132
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
13.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode
register (PnMDIN).
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output
Mode register (PnMDOUT).
Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
Step 4. Assign Port pins to desired peripherals.
Step 5. Enable the Crossbar (XBARE = ‘1’).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pullup, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this
practice is not recommended.
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates
a digital input, and a ‘0’ indicates an analog input. All pins default to digital inputs on reset. See SFR Definition 13.4 for the PnMDIN register details.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pullup is enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is
turned off on an output that is driving a ‘0’ to avoid unnecessary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will determine the
Port I/O pin-assignments based on the XBRn Register settings.
The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output
drivers are disabled while the Crossbar is disabled.
Rev. 1.8
133
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CP1AE
CP1E
CP0AE
CP0E
SYSCKE
SMB0E
SPI0E
URT0E
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE1
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
134
CP1AE: Comparator1 Asynchronous Output Enable
0: Asynchronous CP1 unavailable at Port pin.
1: Asynchronous CP1 routed to Port pin.
CP1E: Comparator1 Output Enable
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
CP0AE: Comparator0 Asynchronous Output Enable
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin.
CP0E: Comparator0 Output Enable
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
SYSCKE: /SYSCLK Output Enable
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
SMB0E: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
SPI0E: SPI I/O Enable
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins.
URT0E: UART I/O Output Enable
0: UART I/O unavailable at Port pin.
1: UART TX0, RX0 routed to Port pins P0.4 and P0.5.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1
R/W
R/W
R/W
R/W
R/W
WEAKPUD
XBARE
T1E
T0E
ECIE
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
Reset Value
Bit0
SFR Address:
PCA0ME
Bit2
Bit1
00000000
0xE2
Bit7:
WEAKPUD: Port I/O Weak Pullup Disable.
0: Weak Pullups enabled (except for Ports whose I/O are configured as analog input).
1: Weak Pullups disabled.
Bit6:
XBARE: Crossbar Enable.
0: Crossbar disabled.
1: Crossbar enabled.
Bit5:
T1E: T1 Enable
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit4:
T0E: T0 Enable
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit3:
ECIE: PCA0 External Counter Input Enable
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Bits2–0: PCA0ME: PCA Module I/O Enable Bits.
000: All PCA I/O unavailable at Port pins.
001: CEX0 routed to Port pin.
010: CEX0, CEX1 routed to Port pins.
011: CEX0, CEX1, CEX2 routed to Port pins.
100: CEX0, CEX1, CEX2, CEX3 routed to Port pins.
101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins.
13.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for
general purpose I/O. Ports3-0 are accessed through corresponding special function registers (SFRs) that
are both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is
latched to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins
are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the
Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the
execution of the read-modify-write instructions. The read-modify-write instructions when operating on a
Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SET, when the
destination is an individual bit in a Port SFR. For these instructions, the value of the register (not the pin) is
read, modified, and written back to the SFR.
Rev. 1.8
135
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.3. P0: Port0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0x80
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0).
Read - Always reads ‘1’ if selected as analog input in register P0MDIN. Directly reads Port
pin when configured as digital input.
0: P0.n pin is logic low.
1: P0.n pin is logic high.
SFR Definition 13.4. P0MDIN: Port0 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF1
Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P0.n pin is configured as an analog input.
1: Corresponding P0.n pin is not configured as an analog input.
136
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.5. P0MDOUT: Port0 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA4
Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push-pull.
Note:
When SDA and SCL appear on any of the Port I/O, each are open-drain regardless of the value of
P0MDOUT.
SFR Definition 13.6. P0SKIP: Port0 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xD4
Bits7–0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
Rev. 1.8
137
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.7. P1: Port1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0x90
Bits7–0: P1.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0).
Read - Always reads ‘1’ if selected as analog input in register P1MDIN. Directly reads Port
pin when configured as digital input.
0: P1.n pin is logic low.
1: P1.n pin is logic high.
Note:
Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices.
SFR Definition 13.8. P1MDIN: Port1 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF2
Bits7–0: Analog Input Configuration Bits for P1.7-P1.0 (respectively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P1.n pin is configured as an analog input.
1: Corresponding P1.n pin is not configured as an analog input.
Note:
138
Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.9. P1MDOUT: Port1 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA5
Bits7–0: Output Configuration Bits for P1.7-P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push-pull.
Note:
Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices.
SFR Definition 13.10. P1SKIP: Port1 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
‘F310/1/2/3/4/5:
00000000
‘F316/7:
11000000
SFR Address:
0xD5
Bits7–0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
Note:
Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices. Hence, in C8051F316/7
devices, user code writing to this SFR should always set P1SKIP[7:6] = 11b so that those two pins are
skipped by the crossbar decoder.
Rev. 1.8
139
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.11. P2: Port2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xA0
Bits7–0: P2.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0).
Read - Always reads ‘1’ if selected as analog input in register P2MDIN. Directly reads Port
pin when configured as digital input.
0: P2.n pin is logic low.
1: P2.n pin is logic high.
Note:
Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices.
SFR Definition 13.12. P2MDIN: Port2 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF3
Bits7–0: Analog Input Configuration Bits for P2.7–P2.0 (respectively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P2.n pin is configured as an analog input.
1: Corresponding P2.n pin is not configured as an analog input.
Note:
140
Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.13. P2MDOUT: Port2 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xA6
Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in register P2MDIN is logic 0.
0: Corresponding P2.n Output is open-drain.
1: Corresponding P2.n Output is push-pull.
Note:
Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices.
SFR Definition 13.14. P2SKIP: Port2 Skip
R/W
R/W
R/W
R/W
-
-
-
-
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD6
Bits7–0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P2.n pin is not skipped by the Crossbar.
1: Corresponding P2.n pin is skipped by the Crossbar.
Note:
Only P2.0–P2.3 are associated with the Crossbar.
Rev. 1.8
141
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.15. P3: Port3
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xB0
Bits7–0: P3.[7:0]
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P3MDOUT.n bit = 0).
Read - Always reads ‘1’ if selected as analog input in register P3MDIN. Directly reads Port
pin when configured as digital input.
0: P3.n pin is logic low.
1: P3.n pin is logic high.
Note:
Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a
Port pin on C8051F311/3/5/6/7 devices.
SFR Definition 13.16. P3MDIN: Port3 Input Mode
R/W
R/W
R/W
-
-
-
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF4
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: Input Configuration Bits for P3.4–P3.0 (respectively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P3.n pin is configured as an analog input.
1: Corresponding P3.n pin is not configured as an analog input.
Note:
142
Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a
Port pin on C8051F311/3/5/6/7 devices.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 13.17. P3MDOUT: Port3 Output Mode
R/W
R/W
R/W
-
-
-
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA7
Bits7–5: UNUSED. Read = 000b; Write - don’t care.
Bits4–0: Output Configuration Bits for P3.4–P3.0 (respectively): ignored if corresponding bit in register P3MDIN is logic 0.
0: Corresponding P3.n Output is open-drain.
1: Corresponding P3.n Output is push-pull.
Note:
Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a
Port pin on C8051F311/3/5/6/7 devices.
Table 13.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified
Parameters
Conditions
Min
IOH = –3 mA, Port I/O push-pull
VDD – 0.7
Output High Voltage
Output Low Voltage
Max
VDD – 0.1
—
—
IOH = –10 mA, Port I/O push-pull
IOL = 8.5 mA
—
VDD – 0.8
—
—
—
0.6
IOL = 10 µA
—
—
0.1
IOL = 25 mA
—
1.0
—
Weak Pullup Off
2.0
—
—
—
—
—
—
0.8
±1
Weak Pullup On, VIN = 0 V
—
25
40
Rev. 1.8
Units
—
IOH = –10 µA, Port I/O push-pull
Input High Voltage
Input Low Voltage
Input Leakage Current
Typ
—
V
V
V
V
µA
143
C8051F310/1/2/3/4/5/6/7
NOTES:
144
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
14. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/10th of the system clock as a master or
slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization,
arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus:
SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data
register, used for both transmitting and receiving SMBus data and slave addresses.
SMB0CN
MT S S A A A S
A X T T CRC I
SMAOK B K
T O
R L
E D
QO
R E
S
T
SMB0CF
E I B E S S S S
N N U XMMMM
S H S T B B B B
M Y H T F CC
B
OOT S S
L E E 1 0
D
00
T0 Overflow
01
T1 Overflow
10
TMR2H Overflow
11
TMR2L Overflow
SMBUS CONTROL LOGIC
Interrupt
Request
Arbitration
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
Data Path
IRQ Generation
Control
SCL
FILTER
SCL
Control
C
R
O
S
S
B
A
R
N
SDA
Control
SMB0DAT
7 6 5 4 3 2 1 0
Port I/O
SDA
FILTER
N
Figure 14.1. SMBus Block Diagram
Rev. 1.8
145
C8051F310/1/2/3/4/5/6/7
14.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
•
•
•
The I2C-Bus and How to Use It (including specifications), Philips Semiconductor.
The I2C-Bus Specification—Version 2.0, Philips Semiconductor.
System Management Bus Specification—Version 1.1, SBS Implementers Forum.
14.2. SMBus Configuration
Figure 14.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when
the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
VDD = 5 V
VDD = 3 V
VDD = 5 V
VDD = 3 V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 14.2. Typical SMBus Configuration
14.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 14.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL.
146
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 14.3 illustrates a typical
SMBus transaction.
SCL
SDA
SLA6
START
SLA5-0
Slave Address + R/W
R/W
D7
ACK
D6-0
Data Byte
NACK
STOP
Figure 14.3. SMBus Transaction
14.3.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section “14.3.4. SCL High (SMBus Free) Timeout”
on page 148). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will
be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and
receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device
always wins, and no data is lost.
Rev. 1.8
147
C8051F310/1/2/3/4/5/6/7
14.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
14.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout.
14.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation.
148
Rev. 1.8
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14.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
•
•
•
•
•
•
•
Byte-wise serial data transfers
Clock signal generation on SCL (Master Mode only) and SDA data synchronization
Timeout/bus error recognition, as defined by the SMB0CF configuration register
START/STOP timing, detection, and generation
Bus arbitration
Interrupt generation
Status information
SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See Section “14.5. SMBus Transfer Modes” on page 157 for more details on transmission
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“14.4.2. SMB0CN Control Register” on page 153; Table 14.4 provides a quick SMB0CN decoding reference.
SMBus configuration options include:
•
•
•
•
Timeout detection (SCL Low Timeout and/or Bus Free Timeout)
SDA setup and hold time extensions
Slave event enable/disable
Clock source selection
These options are selected in the SMB0CF register, as described in Section “14.4.1. SMBus Configuration Register” on page 150.
Rev. 1.8
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14.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
Table 14.1. SMBus Clock Source Selection
SMBCS1
0
0
1
1
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 14.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “17. Timers” on page 187.
Equation 14.1. Minimum SCL High and Low Times
1
T HighMin = T LowMin = ---------------------------------------------f ClockSourceOverflow
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 14.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 14.2.
Equation 14.2. Typical SMBus Bit Rate
f ClockSourceOverflow
BitRate = ---------------------------------------------3
150
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Figure 14.4 shows the typical SCL generation described by Equation 14.2. Notice that THIGH is typically
twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 14.1.
Timer Source
Overflows
SCL
TLow
THigh
SCL High Timeout
Figure 14.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high.
The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable
after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 14.2 shows the minimum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically
necessary when SYSCLK is above 10 MHz.
Table 14.2. Minimum SDA Setup and Hold Times
EXTHOLD
Minimum SDA Setup Time
Tlow – 4 system clocks
Minimum SDA Hold Time
0
OR
3 system clocks
1
1 system clock + s/w delay*
11 system clocks
12 system clocks
*Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w
delay occurs between the time SMB0DAT or ACK is written and when SI is cleared.
Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w
delay is zero.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “14.3.3. SCL Low Timeout” on page 148). The SMBus interface will force Timer 3
to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 14.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an
interrupt will be generated, and STO will be set).
Rev. 1.8
151
C8051F310/1/2/3/4/5/6/7
SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration
R/W
R/W
R
ENSMB
INH
BUSY
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
EXTHOLD SMBTOE SMBFTE SMBCS1
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
SMBCS0 00000000
Bit0
SFR Address: 0xC1
Bit7:
ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins.
0: SMBus interface disabled.
1: SMBus interface enabled.
Bit6:
INH: SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events
occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5:
BUSY: SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0
when a STOP or free-timeout is sensed.
Bit4:
EXTHOLD: SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and hold times according to Table 14.2.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3:
SMBTOE: SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to
reload while SCL is high and allows Timer 3 to count when SCL goes low. If Timer 3 is configured in split mode (T3SPLIT is set), only the high byte of Timer 3 is held in reload while
SCL is high. Timer 3 should be programmed to generate interrupts at 25 ms, and the
Timer 3 interrupt service routine should reset SMBus communication.
Bit2:
SMBFTE: SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for
more than 10 SMBus clock source periods.
Bits1–0: SMBCS1-SMBCS0: SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus bit
rate. The selected device should be configured according to Equation 14.1.
SMBCS1
0
0
1
1
152
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
14.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 14.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating
that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing
value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit
before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit;
however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further
slave events will be ignored until the next START is detected.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared.
The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or
when an arbitration is lost; see Table 14.3 for more details.
Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 14.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 14.4 for SMBus status decoding using the SMB0CN register.
Rev. 1.8
153
C8051F310/1/2/3/4/5/6/7
SFR Definition 14.2. SMB0CN: SMBus Control
R
R
MASTER TXMODE
Bit7
Bit6
R/W
R/W
STA
STO
Bit5
Bit4
R
R
ACKRQ ARBLOST
Bit3
Bit2
R/W
R/W
Reset Value
ACK
SI
00000000
Bit1
Bit0
Bit Addressable
SFR Address: 0xC0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
154
MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operating as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operating as a master, a START condition is transmitted if the bus is free (If the bus
is not free, the START is transmitted after a STOP is received or a timeout is detected). If
STA is set by software as an active Master, a repeated START will be generated after the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Start detected.
STO: SMBus Stop Flag.
Write:
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK
cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA
and STO are set, a STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode).
ACKRQ: SMBus Acknowledge Request
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK
bit to be written with the correct ACK response value.
ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a
transmitter. A lost arbitration while a slave indicates a bus error condition.
ACK: SMBus Acknowledge Flag.
This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if
in Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 14.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
Table 14.3. Sources for Hardware Changes to SMB0CN
Bit
MASTER
TXMODE
STA
STO
ACKRQ
ARBLOST
ACK
SI
Set by Hardware When...
• A START is generated.
• START is generated.
• SMB0DAT is written before the start of an
SMBus frame.
• A START followed by an address byte is
received.
• A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A byte has been received and an ACK
response value is needed.
• A repeated START is detected as a MASTER
when STA is low (unwanted repeated START).
• SCL is sensed low while attempting to generate a STOP or repeated START condition.
• SDA is sensed low while transmitting a ‘1’
(excluding ACK bits).
• The incoming ACK value is low (ACKNOWLEDGE).
• A START has been generated.
• Lost arbitration.
• A byte has been transmitted and an
ACK/NACK received.
• A byte has been received.
• A START or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
Rev. 1.8
Cleared by Hardware When...
• A STOP is generated.
• Arbitration is lost.
• A START is detected.
• Arbitration is lost.
• SMB0DAT is not written before the
start of an SMBus frame.
• Must be cleared by software.
• A pending STOP is generated.
• After each ACK cycle.
• Each time SI is cleared.
• The incoming ACK value is high (NOT
ACKNOWLEDGE).
• Must be cleared by software.
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14.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 14.3. SMB0DAT: SMBus Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC2
Bits7–0: SMB0DAT: SMBus Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read
from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to
logic 1. The serial data in the register remains stable as long as the SI flag is set. When the
SI flag is not set, the system may be in the process of shifting data in/out and the CPU
should not attempt to access this register.
156
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
14.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter.
14.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates
the START condition and transmits the first byte containing the address of the target slave and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits
one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the
slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will
switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 14.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any
number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK
cycle in this mode.
S
SLA
W
Interrupt
A
Interrupt
Data Byte
A
Data Byte
Interrupt
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 14.5. Typical Master Transmitter Sequence
Rev. 1.8
157
C8051F310/1/2/3/4/5/6/7
14.5.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the
START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the
slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial
data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write
the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit generates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last
byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and
a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written
while an active Master Receiver. Figure 14.6 shows a typical Master Receiver sequence. Two received
data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’
interrupts occur before the ACK cycle in this mode.
S
SLA
R
Interrupt
A
Interrupt
Data Byte
A
Interrupt
Data Byte
N
Interrupt
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 14.6. Typical Master Receiver Sequence
158
Rev. 1.8
P
C8051F310/1/2/3/4/5/6/7
14.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit
(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the
ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received
slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until
the next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 14.7 shows a typical Slave
Receiver sequence. Two received data bytes are shown, though any number of bytes may be received.
Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode.
Interrupt
S
SLA
W
A
Interrupt
Data Byte
A
Interrupt
Data Byte
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 14.7. Typical Slave Receiver Sequence
Rev. 1.8
159
C8051F310/1/2/3/4/5/6/7
14.5.4. Slave Transmitter Mode
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH
= 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a
slave address and direction bit (READ in this case) is received. Upon entering Slave Transmitter Mode, an
interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an
ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave
interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data
should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the
acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is
a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface
exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver
Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 14.8 shows a typical Slave
Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode.
Interrupt
S
SLA
R
A
Interrupt
Data Byte
A
Data Byte
Interrupt
N
P
Interrupt
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 14.8. Typical Slave Transmitter Sequence
160
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
14.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform to the SMBus specification. Highlighted responses are allowed but do not conform to
the SMBus specification.
Table 14.4. SMBus Status Decoding
Values
Written
ARBLOST
ACK
0
X
0
0
1100
0
1000
1
0
0
A master START was
generated.
A master data or address byte
0 was transmitted; NACK
received.
Load slave address + R/W into
SMB0DAT.
Set STA to restart transfer.
Abort transfer.
Load next data byte into SMB0DAT.
End transfer with STOP.
A master data or address byte End transfer with STOP and start
another transfer.
1 was transmitted; ACK
received.
Send repeated START.
Switch to Master Receiver Mode
(clear SI without writing new data
to SMB0DAT).
Acknowledge received byte; Read
SMB0DAT.
Send NACK to indicate last byte,
and send STOP.
Send NACK to indicate last byte,
and send STOP followed by
START.
Send ACK followed by repeated
A master data byte was
START.
X
received; ACK requested.
Send NACK to indicate last byte,
and send repeated START.
Send ACK and switch to Master
Transmitter Mode (write to SMB0DAT before clearing SI).
Send NACK and switch to Master
Transmitter Mode (write to SMB0DAT before clearing SI).
Rev. 1.8
ACK
ACKRQ
0
Typical Response Options
STO
Status
Vector
1110
Current SMbus State
STA
Master Receiver
Master Transmitter
Mode
Values Read
0
0
X
1
0
X
0
1
X
0
0
X
0
1
X
1
1
X
1
0
X
0
0
X
0
0
1
0
1
0
1
1
0
1
0
1
1
0
0
0
0
1
0
0
0
161
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Table 14.4. SMBus Status Decoding (Continued)
Values
Written
0
0
1
0
X
1
0
0010
Slave Receiver
1
0010
0001
1
X
A slave address was
received; ACK requested.
Lost arbitration as master;
X slave address received; ACK
requested.
1
1
1
0
0
0
1
X
0
A slave byte was received;
X
ACK requested.
1
1
1
X
Lost arbitration while attempting a repeated START.
0
0000
162
A slave byte was transmitted;
NACK received.
A slave byte was transmitted;
1
ACK received.
A Slave byte was transmitted;
X
error detected.
A STOP was detected while
X an addressed Slave Transmitter.
0
Lost arbitration while attempting a STOP.
A STOP was detected while
X
an addressed slave receiver.
X
X
Lost arbitration due to a
detected STOP.
Lost arbitration while transmitting a data byte as master.
No action required (expecting
STOP condition).
Load SMB0DAT with next data
byte to transmit.
No action required (expecting
Master to end transfer).
No action required (transfer complete).
Acknowledge received address.
Do not acknowledge received
address.
Acknowledge received address.
Do not acknowledge received
address.
Reschedule failed transfer; do not
acknowledge received address.
Abort failed transfer.
Reschedule failed transfer.
No action required (transfer complete/aborted).
No action required (transfer complete).
Abort transfer.
Reschedule failed transfer.
Acknowledge received byte; Read
SMB0DAT.
Do not acknowledge received
byte.
Abort failed transfer.
Reschedule failed transfer.
Rev. 1.8
ACK
0
Typical Response Options
STO
0
ACK
0
Current SMbus State
STA
0101
ARBLOST
Status
Vector
0100
ACKRQ
Slave Transmitter
Mode
Values Read
0
0
X
0
0
X
0
0
X
0
0
X
0
0
1
0
0
0
0
0
1
0
0
0
1
0
0
0
1
0
0
X
X
0
0
0
0
0
X
0
1
0
0
X
X
0
0
1
0
0
0
0
1
0
0
0
0
C8051F310/1/2/3/4/5/6/7
15. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “15.1. Enhanced Baud Rate Generation” on page 164). Received data buffering allows
UART0 to start reception of a second incoming data byte before software has finished reading the previous
data byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit register. Reads of SBUF0 always access the buffered Receive register;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF
TB8
SBUF
(TX Shift)
SET
D
Q
TX
CLR
Crossbar
Zero Detector
Stop Bit
Shift
Start
Data
Tx Control
Tx Clock
Send
Tx IRQ
SCON
TI
Serial
Port
Interrupt
MCE
REN
TB8
RB8
TI
RI
SMODE
UART Baud
Rate Generator
Port I/O
RI
Rx IRQ
Rx Clock
Rx Control
Start
Shift
0x1FF
Load
SBUF
RB8
Input Shift Register
(9 bits)
Load SBUF
SBUF
(RX Latch)
Read
SBUF
SFR Bus
RX
Crossbar
Figure 15.1. UART0 Block Diagram
Rev. 1.8
163
C8051F310/1/2/3/4/5/6/7
15.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 15.2), which is not useraccessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1
TL1
UART
Overflow
2
TX Clock
Overflow
2
RX Clock
TH1
Start
Detected
RX Timer
Figure 15.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “17.1.3. Mode 2: 8-bit
Counter/Timer with Auto-Reload” on page 189). The Timer 1 reload value should be set so that overflows will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by
one of six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or
an external input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by
Equation 15.1.
Equation 15.1. UART0 Baud Rate
T1 CLK
1
UartBaudRate = ------------------------------- -- 256 – T1H 2
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “17. Timers” on page 187. A quick
reference for typical baud rates and system clock frequencies is given in Table 15.1 through Table 15.6.
Note that the internal oscillator may still generate the system clock when the external oscillator is driving
Timer 1.
164
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
15.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown in Figure 15.3.
TX
RS-232
LEVEL
XLTR
RS-232
RX
C8051Fxxx
OR
TX
TX
RX
RX
MCU
C8051Fxxx
Figure 15.3. UART Interconnect Diagram
15.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits
are lost.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
STOP
BIT
BIT TIMES
BIT SAMPLING
Figure 15.4. 8-Bit UART Timing Diagram
Rev. 1.8
165
C8051F310/1/2/3/4/5/6/7
15.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80
(SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB80 (SCON0.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to ‘1’. If the above conditions are not met,
SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to ‘1’. A UART0 interrupt will occur if
enabled when either TI0 or RI0 is set to ‘1’.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
BIT TIMES
BIT SAMPLING
Figure 15.5. 9-Bit UART Timing Diagram
166
Rev. 1.8
D7
D8
STOP
BIT
C8051F310/1/2/3/4/5/6/7
15.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Master
Device
Slave
Device
Slave
Device
Slave
Device
V+
RX
TX
RX
TX
RX
TX
RX
TX
Figure 15.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 1.8
167
C8051F310/1/2/3/4/5/6/7
SFR Definition 15.1. SCON0: Serial Port 0 Control
R/W
R
S0MODE
Bit7
Bit6
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
MCE0
REN0
TB80
RB80
TI0
RI0
01000000
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit Addressable
SFR Address: 0x98
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
168
S0MODE: Serial Port 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: 8-bit UART with Variable Baud Rate.
1: 9-bit UART with Variable Baud Rate.
UNUSED. Read = 1b. Write = don’t care.
MCE0: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
S0MODE = 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
S0MODE = 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
REN0: Receive Enable.
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
RB80: Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0
interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service
routine. This bit must be cleared manually by software.
RI0: Receive Interrupt Flag.
Set to ‘1’ by hardware when a byte of data has been received by UART0 (set at the STOP bit
sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART0 interrupt service routine. This bit must be cleared manually by software.
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x99
Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB–LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch.
Rev. 1.8
169
C8051F310/1/2/3/4/5/6/7
SYSCLK from
Internal Osc.
Table 15.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
Frequency: 24.5 MHz
Oscilla- Timer Clock
SCA1-SCA0
T1M*
Timer 1
tor Divide
Source
(pre-scale
Reload Value
Factor
select)*
(hex)
–0.32%
106
SYSCLK
XX
1
0xCB
–0.32%
212
SYSCLK
XX
1
0x96
0.15%
426
SYSCLK
XX
1
0x2B
–0.32%
848
SYSCLK / 4
01
0
0x96
0.15%
1704
SYSCLK / 12
00
0
0xB9
–0.32%
2544
SYSCLK / 12
00
0
0x96
–0.32%
10176
SYSCLK / 48
10
0
0x96
0.15%
20448
SYSCLK / 48
10
0
0x2B
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
Baud Rate
% Error
SYSCLK from SYSCLK from
Internal Osc. External Osc.
Table 15.2. Timer Settings for Standard Baud Rates
Using an External 25 MHz Oscillator
Target
Baud Rate
(bps)
Baud Rate
% Error
230400
115200
57600
28800
14400
9600
2400
1200
57600
28800
14400
–0.47%
0.45%
–0.01%
0.45%
–0.01%
0.15%
0.45%
–0.01%
–0.47%
–0.47%
0.45%
9600
0.15%
Frequency: 25.0 MHz
Oscilla- Timer Clock
SCA1-SCA0
tor Divide
Source
(pre-scale
Factor
select)*
108
SYSCLK
XX
218
SYSCLK
XX
434
SYSCLK
XX
872
SYSCLK / 4
01
1736
SYSCLK / 4
01
2608
EXTCLK / 8
11
10464
SYSCLK / 48
10
20832
SYSCLK / 48
10
432
EXTCLK / 8
11
864
EXTCLK / 8
11
1744
EXTCLK / 8
11
2608
EXTCLK / 8
11
T1M*
Timer 1
Reload Value
(hex)
1
1
1
0
0
0
0
0
0
0
0
0xCA
0x93
0x27
0x93
0x27
0x5D
0x93
0x27
0xE5
0xCA
0x93
0
0x5D
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
170
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 15.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Frequency: 22.1184 MHz
Oscilla- Timer Clock SCA1-SCA0 T1M*
Timer 1
tor Divide
Source
(pre-scale
Reload Value
Factor
select)*
(hex)
0.00%
96
SYSCLK
XX
1
0xD0
0.00%
192
SYSCLK
XX
1
0xA0
0.00%
384
SYSCLK
XX
1
0x40
0.00%
768
SYSCLK / 12
00
0
0xE0
0.00%
1536
SYSCLK / 12
00
0
0xC0
0.00%
2304
SYSCLK / 12
00
0
0xA0
0.00%
9216
SYSCLK / 48
10
0
0xA0
0.00%
18432
SYSCLK / 48
10
0
0x40
0.00%
96
EXTCLK / 8
11
0
0xFA
0.00%
192
EXTCLK / 8
11
0
0xF4
0.00%
384
EXTCLK / 8
11
0
0xE8
0.00%
768
EXTCLK / 8
11
0
0xD0
0.00%
1536
EXTCLK / 8
11
0
0xA0
0.00%
2304
EXTCLK / 8
11
0
0x70
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
Baud Rate
% Error
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 15.4. Timer Settings for Standard Baud Rates
Using an External 18.432 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Frequency: 18.432 MHz
Oscilla- Timer Clock
SCA1-SCA0
T1M*
Timer 1
tor Divide
Source
(pre-scale
Reload
Factor
select)*
Value (hex)
0.00%
80
SYSCLK
XX
1
0xD8
0.00%
160
SYSCLK
XX
1
0xB0
0.00%
320
SYSCLK
XX
1
0x60
0.00%
640
SYSCLK / 4
01
0
0xB0
0.00%
1280
SYSCLK / 4
01
0
0x60
0.00%
1920
SYSCLK / 12
00
0
0xB0
0.00%
7680
SYSCLK / 48
10
0
0xB0
0.00%
15360
SYSCLK / 48
10
0
0x60
0.00%
80
EXTCLK / 8
11
0
0xFB
0.00%
160
EXTCLK / 8
11
0
0xF6
0.00%
320
EXTCLK / 8
11
0
0xEC
0.00%
640
EXTCLK / 8
11
0
0xD8
0.00%
1280
EXTCLK / 8
11
0
0xB0
0.00%
1920
EXTCLK / 8
11
0
0x88
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
Baud Rate
% Error
Rev. 1.8
171
C8051F310/1/2/3/4/5/6/7
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 15.5. Timer Settings for Standard Baud Rates
Using an External 11.0592 MHz Oscillator
Frequency: 11.0592 MHz
Target
Baud Rate
Oscilla- Timer Clock
SCA1-SCA0
T1M*
Timer 1
Baud Rate
% Error
tor Divide
Source
(pre-scale
Reload Value
(bps)
Factor
select)*
(hex)
230400
0.00%
48
SYSCLK
XX
1
0xE8
115200
0.00%
96
SYSCLK
XX
1
0xD0
57600
0.00%
192
SYSCLK
XX
1
0xA0
28800
0.00%
384
SYSCLK
XX
1
0x40
14400
0.00%
768
SYSCLK / 12
00
0
0xE0
9600
0.00%
1152
SYSCLK / 12
00
0
0xD0
2400
0.00%
4608
SYSCLK / 12
00
0
0x40
1200
0.00%
9216
SYSCLK / 48
10
0
0xA0
230400
0.00%
48
EXTCLK / 8
11
0
0xFD
115200
0.00%
96
EXTCLK / 8
11
0
0xFA
57600
0.00%
192
EXTCLK / 8
11
0
0xF4
28800
0.00%
384
EXTCLK / 8
11
0
0xE8
14400
0.00%
768
EXTCLK / 8
11
0
0xD0
9600
0.00%
1152
EXTCLK / 8
11
0
0xB8
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 15.6. Timer Settings for Standard Baud Rates
Using an External 3.6864 MHz Oscillator
172
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Frequency: 3.6864 MHz
Oscilla- Timer Clock
SCA1-SCA0
T1M*
Timer 1
tor Divide
Source
(pre-scale
Reload
Factor
select)*
Value (hex)
16
SYSCLK
XX
1
0xF8
32
SYSCLK
XX
1
0xF0
64
SYSCLK
XX
1
0xE0
128
SYSCLK
XX
1
0xC0
256
SYSCLK
XX
1
0x80
384
SYSCLK
XX
1
0x40
1536
SYSCLK / 12
00
0
0xC0
3072
SYSCLK / 12
00
0
0x80
16
EXTCLK / 8
11
0
0xFF
32
EXTCLK / 8
11
0
0xFE
64
EXTCLK / 8
11
0
0xFC
128
EXTCLK / 8
11
0
0xF8
256
EXTCLK / 8
11
0
0xF0
384
EXTCLK / 8
11
0
0xE8
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1.
Baud
Rate%
Error
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Rev. 1.8
C8051F310/1/2/3/4/5/6/7
16. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode.
SFR Bus
SYSCLK
SPI0CN
SPIF
WCOL
MODF
RXOVRN
NSSMD1
NSSMD0
TXBMT
SPIEN
SPI0CFG
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CKR
Clock Divide
Logic
SPI CONTROL LOGIC
Data Path
Control
SPI IRQ
Pin Interface
Control
MOSI
Tx Data
SPI0DAT
SCK
Transmit Data Buffer
Shift Register
7 6 5 4 3 2 1 0
Rx Data
Pin
Control
Logic
Receive Data Buffer
MISO
C
R
O
S
S
B
A
R
Port I/O
NSS
Read
SPI0DAT
Write
SPI0DAT
SFR Bus
Figure 16.1. SPI Block Diagram
Rev. 1.8
173
C8051F310/1/2/3/4/5/6/7
16.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
16.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
16.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
16.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
16.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
•
•
•
NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is
disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select
signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-topoint communication between a master and one slave.
NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is
enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a
master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple master devices can be used on the same SPI bus.
NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration
should only be used when operating SPI0 as a master device.
See Figure 16.2, Figure 16.3, and Figure 16.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “13. Port Input/Output” on page 129 for general purpose
port I/O and crossbar information.
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16.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is
used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this
mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a
Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumstances. In multi-master systems, devices will
typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 16.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 16.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 16.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
Rev. 1.8
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C8051F310/1/2/3/4/5/6/7
Master
Device 1
NSS
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
GPIO
NSS
Master
Device 2
Figure 16.2. Multiple-Master Mode Connection Diagram
Master
Device
MISO
MISO
MOSI
MOSI
SCK
SCK
Slave
Device
Figure 16.3. 3-Wire Single Master and Slave Mode Connection Diagram
Master
Device
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
NSS
NSS
MISO
MOSI
Slave
Device
Slave
Device
SCK
NSS
Figure 16.4. 4-Wire Single Master and Slave Mode Connection Diagram
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16.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are doublebuffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit
buffer will immediately be transferred into the shift register. When the shift register already contains data,
the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or
current) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 16.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and reenabling SPI0 with the SPIEN bit. Figure 16.3 shows a connection diagram between a slave device in 3wire slave mode and a master device.
16.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed and the receive buffer still holds an unread byte from a previous
transfer. The new byte is not transferred to the receive buffer, allowing the previously received
data byte to be read. The data byte which caused the overrun is lost.
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16.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 16.5. For slave mode, the clock and
data relationships are shown in Figure 16.6 and Figure 16.7. CKPHA must be set to ‘0’ on both the master
and slave SPI when communicating between two of the following devices: C8051F04x, C8051F06x,
C8051F12x, C8051F31x, C8051F32x, and C8051F33x
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 16.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s
system clock.
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
NSS (Must Remain High
in Multi-Master Mode)
Figure 16.5. Master Mode Data/Clock Timing
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Rev. 1.8
Bit 1
Bit 0
C8051F310/1/2/3/4/5/6/7
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (4-Wire Mode)
Figure 16.6. Slave Mode Data/Clock Timing (CKPHA = 0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=1)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Bit 0
NSS (4-Wire Mode)
Figure 16.7. Slave Mode Data/Clock Timing (CKPHA = 1)
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16.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following register definitions.
SFR Definition 16.1. SPI0CFG: SPI0 Configuration
R
R/W
R/W
R/W
R
R
R
R
Reset Value
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
00000111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA1
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
*Note:
180
SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode).
MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK period.*
CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at the time that
the register is read. This input is not de-glitched.
SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buffer or write to the
receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information available in the receive buffer that has not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is
sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave
device. See Table 16.1 for timing parameters.
Rev. 1.8
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SFR Definition 16.2. SPI0CN: SPI0 Control
R/W
R/W
R/W
SPIF
WCOL
MODF
Bit7
Bit6
Bit5
R/W
R/W
R/W
RXOVRN NSSMD1 NSSMD0
Bit4
Bit3
Bit2
R
R/W
Reset Value
TXBMT
SPIEN
00000110
Bit1
Bit0
Bit
Addressable
SFR Address: 0xF8
Bit 7:
SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 6:
WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to
the SPI0 data register was attempted while a data transfer was in progress. It must be
cleared by software.
Bit 5:
MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software.
Bit 4:
RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “16.2. SPI0 Master Mode Operation” on page 175 and Section “16.3. SPI0
Slave Mode Operation” on page 177).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1:
TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
Bit 0:
SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
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SFR Definition 16.3. SPI0CKR: SPI0 Clock Rate
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA2
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation, where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK
f SCK = ------------------------------------------------2 SPI0CKR + 1
for 0
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