C8051F2xx
8K ISP FLASH MCU Family
Analog Peripherals
- SAR ADC
•
•
•
•
•
-
12-bit resolution ('F206)
8-bit resolution ('F220/1/6)
±1/4 LSB INL (8-bit) and ±2 LSB INL (12-bit)
Up to 100 ksps
Up to 32 channel input multiplexer; each port
I/O pin can be an ADC input
Two Comparators
•
•
16 programmable hysteresis states
Configurable to generate interrupts or reset
- VDD monitor and brown-out detector
On-Chip JTAG Debug
- On-chip debug circuitry facilitates full speed,
-
non-intrusive in-system debug (No emulator
required)
Provides breakpoints, single-stepping, watchpoints,
stack monitor
Inspect/modify memory and registers
Superior performance to emulation systems using
ICE-chips, target pods, and sockets
Complete, low cost development kit
Memory
- 256 bytes internal data RAM
- 1024 bytes XRAM (available on 'F206/226/236)
- 8 kB Flash; In-system programmable in 512 byte
sectors
Digital Peripherals
- Four byte wide Port I/O; All are 5 V tolerant
- Hardware UART and SPI bus
- 3 general purpose 16-bit counter/timers
- Dedicated watch-dog timer
- Bi-directional reset
- System clock: internal programmable oscillator,
external crystal, external RC, or external clock
Supply Voltage
2.7 to 3.6 V
- Typical operating current: 10 mA @ 25 MHz
- Multiple power saving sleep and shutdown modes
(48-Pin TQFP and 32-Pin LQFP Version
Available)
Temperature Range: –40 to +85 °C
High Speed
- 8051 mC Core
- Pipelined Instruction Architecture; Executes 70% of
-
Instructions in 1 or 2 System Clocks
Up to 25MIPS Throughput with 25MHz Clock
Expanded Interrupt Handler
Rev. 1.7 10/22
Copyright © 2022 by Silicon Laboratories
C8051F2xx-DS14
C8051F2xx
NOTES:
2
Rev. 1.7
C8051F2xx
Table of Contents
1. System Overview.................................................................................................... 11
1.1. CIP-51TM Microcontroller Core ........................................................................ 15
1.1.1. Fully 8051 Compatible.............................................................................. 15
1.1.2. Improved Throughput ............................................................................... 15
1.1.3. Additional Features .................................................................................. 16
1.2. On-Board Memory ............................................................................................ 17
1.3. JTAG ............................................................................................................ 18
1.4. Digital/Analog Configurable I/O......................................................................... 19
1.5. Serial Ports ....................................................................................................... 20
1.6. Analog to Digital Converter ............................................................................... 20
1.7. Comparators ..................................................................................................... 21
2. Absolute Maximum Ratings .................................................................................. 23
3. Global DC Electrical Characteristics .................................................................... 24
4. Pinout and Package Definitions............................................................................ 25
5. ADC (8-Bit, C8051F220/1/6 Only)........................................................................... 32
5.1. Analog Multiplexer and PGA............................................................................. 32
5.2. ADC Modes of Operation.................................................................................. 33
5.3. ADC Programmable Window Detector ............................................................. 37
6. ADC (12-Bit, C8051F206 Only)............................................................................... 40
6.1. Analog Multiplexer and PGA............................................................................. 40
6.2. ADC Modes of Operation.................................................................................. 41
6.3. ADC Programmable Window Detector ............................................................. 46
7. Voltage Reference (C8051F206/220/221/226) ....................................................... 50
8. Comparators ........................................................................................................... 52
9. CIP-51 Microcontroller ........................................................................................... 58
9.1. Instruction Set ................................................................................................... 60
9.1.1. Instruction and CPU Timing ..................................................................... 60
9.1.2. MOVX Instruction and Program Memory ................................................. 60
9.2. Memory Organization........................................................................................ 65
9.2.1. Program Memory...................................................................................... 65
9.2.2. Data Memory............................................................................................ 65
9.2.3. General Purpose Registers ...................................................................... 66
9.2.4. Bit Addressable Locations........................................................................ 66
9.2.5. Stack ....................................................................................................... 67
9.3. Special Function Registers ............................................................................... 68
9.3.1. Register Descriptions ............................................................................... 71
9.4. Interrupt Handler ............................................................................................... 74
9.4.1. MCU Interrupt Sources and Vectors ........................................................ 74
9.4.2. External Interrupts .................................................................................... 74
9.4.3. Software Controlled Interrupts.................................................................. 74
9.4.4. Interrupt Priorities ..................................................................................... 76
9.4.5. Interrupt Latency ...................................................................................... 76
9.4.6. Interrupt Register Descriptions................................................................. 77
Rev. 1.7
3
C8051F2xx
9.5. Power Management Modes .............................................................................. 83
9.5.1. Idle Mode.................................................................................................. 83
9.5.2. Stop Mode ................................................................................................ 83
10. Flash Memory ......................................................................................................... 85
10.1.Programming The Flash Memory ..................................................................... 85
10.2.Security Options ............................................................................................... 86
11. On-Chip XRAM (C8051F206/226/236).................................................................... 90
12. Reset Sources......................................................................................................... 91
12.1.Power-on Reset................................................................................................ 92
12.2.Software Forced Reset..................................................................................... 92
12.3.Power-fail Reset ............................................................................................... 92
12.4.External Reset .................................................................................................. 93
12.5.Missing Clock Detector Reset .......................................................................... 93
12.6.Comparator 0 Reset ......................................................................................... 93
12.7.Watchdog Timer Reset..................................................................................... 93
12.7.1.Watchdog Usage...................................................................................... 93
13. Oscillator ................................................................................................................. 97
13.1.External Crystal Example ............................................................................... 100
13.2.External RC Example ..................................................................................... 100
13.3.External Capacitor Example ........................................................................... 100
14. Port Input/Output.................................................................................................. 101
14.1.Port I/O Initialization ....................................................................................... 101
14.2.General Purpose Port I/O ............................................................................... 105
15. Serial Peripheral Interface Bus ........................................................................... 110
15.1.Signal Descriptions......................................................................................... 111
15.1.1.Master Out, Slave In .............................................................................. 111
15.1.2.Master In, Slave Out .............................................................................. 111
15.1.3.Serial Clock ............................................................................................ 111
15.1.4.Slave Select ........................................................................................... 111
15.2.Serial Clock Timing......................................................................................... 113
15.3.SPI Special Function Registers ...................................................................... 113
16. UART...................................................................................................................... 117
16.1.UART Operational Modes .............................................................................. 118
16.1.1.Mode 0: Synchronous Mode .................................................................. 118
16.1.2.Mode 1: 8-Bit UART, Variable Baud Rate.............................................. 119
16.1.3.Mode 2: 9-Bit UART, Fixed Baud Rate .................................................. 121
16.1.4.Mode 3: 9-Bit UART, Variable Baud Rate.............................................. 121
16.2.Multiprocessor Communications .................................................................... 122
17. Timers.................................................................................................................... 125
17.1.Timer 0 and Timer 1 ....................................................................................... 125
17.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 125
17.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 126
17.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 127
17.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 128
4
Rev. 1.7
C8051F2xx
17.2.Timer 2 .......................................................................................................... 133
17.2.1.Mode 0: 16-bit Counter/Timer with Capture ........................................... 134
17.2.2.Mode 1: 16-bit Counter/Timer with Auto-Reload.................................... 135
17.2.3.Mode 2: Baud Rate Generator ............................................................... 136
18. JTAG ...................................................................................................................... 139
18.1.Flash Programming Commands..................................................................... 140
18.2.Boundary Scan Bypass and ID Code ............................................................. 143
18.2.1.BYPASS Instruction ............................................................................... 143
18.2.2.IDCODE Instruction................................................................................ 143
18.3.Debug Support ............................................................................................... 143
Contact Information.................................................................................................. 144
Rev. 1.7
5
C8051F2xx
NOTES:
6
Rev. 1.7
C8051F2xx
List of Figures and Tables
1. System Overview
Table 1.1. Product Selection Guide ........................................................................ 11
Figure 1.1. C8051F206, C8051F220 and C8051F226 Block Diagram (48 TQFP) .. 12
Figure 1.2. C8051F221 Block Diagram (32 LQFP) .................................................. 13
Figure 1.3. C8051F230 and C8051F236 Block Diagram (48 TQFP) ....................... 14
Figure 1.4. C8051F231 Block Diagram (32 LQFP) .................................................. 15
Figure 1.5. Comparison of Peak MCU Throughputs ................................................ 16
Figure 1.6. Comparison of Peak MCU Throughputs ................................................ 17
Figure 1.7. On-Board Memory Map.......................................................................... 18
Figure 1.8. Degub Environment Diagram................................................................. 19
Figure 1.9. Port I/O Functional Block Diagram......................................................... 20
Figure 1.10. ADC Diagram ....................................................................................... 21
Figure 1.11. Comparator Diagram............................................................................ 22
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings* .................................................................. 23
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics ...................................................... 24
4. Pinout and Package Definitions
Table 4.1. Pin Definitions ........................................................................................ 25
Figure 4.1. TQFP-48 Pin Diagram............................................................................ 28
Figure 4.2. LQFP-32 Pin Diagram............................................................................ 29
Figure 4.3. TQFP-48 Package Drawing ................................................................... 30
Figure 4.4. LQFP-32 Package Drawing ................................................................... 31
5. ADC (8-Bit, C8051F220/1/6 Only)
Figure 5.1. 8-Bit ADC Functional Block Diagram ..................................................... 32
Figure 5.2. 12-Bit ADC Track and Conversion Example Timing .............................. 33
Figure 5.3. 8-Bit ADC Window Interrupt Examples .................................................. 38
Table 5.1. 8-Bit ADC Electrical Characteristics....................................................... 39
6. ADC (12-Bit, C8051F206 Only)
Figure 6.1. 12-Bit ADC Functional Block Diagram ................................................... 40
Figure 6.2. 12-Bit ADC Track and Conversion Example Timing .............................. 41
Figure 6.3. 12-Bit ADC Window Interrupt Examples, Right Justified Data ............... 47
Figure 6.4. 12-Bit ADC Window Interrupt Examples, Left Justified Data ................. 48
Table 6.1. 12-Bit ADC Electrical Characteristics (C8015F206 only) ....................... 49
7. Voltage Reference (C8051F206/220/221/226)
Figure 7.1. Voltage Reference Functional Block Diagram ....................................... 50
Table 7.1. Reference Electrical Characteristics ...................................................... 51
8. Comparators
Figure 8.1. Comparator Functional Block Diagram .................................................. 53
Figure 8.2. Comparator Hysteresis Plot ................................................................... 54
Table 8.1. Comparator Electrical Characteristics.................................................... 57
9. CIP-51 Microcontroller
Figure 9.1. CIP-51 Block Diagram............................................................................ 58
Rev. 1.7
7
C8051F2xx
Table 9.1. CIP-51 Instruction Set Summary............................................................ 60
Figure 9.2. Memory Map .......................................................................................... 66
Table 9.2. Special Function Register Memory Map ................................................ 68
Table 9.3. Special Function Registers .................................................................... 69
Table 9.4. Interrupt Summary ................................................................................. 75
10. Flash Memory
Table 10.1. Flash Memory Electrical Characteristics ............................................... 86
Figure 10.1. Flash Program Memory Security Bytes................................................ 87
11. On-Chip XRAM (C8051F206/226/236)
12. Reset Sources
Figure 12.1. Reset Sources Diagram ....................................................................... 91
Figure 12.2. VDD Monitor Timing Diagram .............................................................. 92
Table 12.1. VDD Monitor Electrical Characteristics.................................................. 96
13. Oscillator
Figure 13.1. Oscillator Diagram................................................................................ 97
Table 13.1. Internal Oscillator Electrical Characteristics .......................................... 98
14. Port Input/Output
Figure 14.1. Port I/O Functional Block Diagram ..................................................... 102
Figure 14.2. Port I/O Cell Block Diagram ............................................................... 102
Table 14.1. Port I/O DC Electrical Characteristics.................................................. 109
15. Serial Peripheral Interface Bus
Figure 15.1. SPI Block Diagram ............................................................................. 110
Figure 15.2. SPI Block Diagram ............................................................................. 111
Figure 15.3. Full Duplex Operation......................................................................... 112
Figure 15.4. Full Duplex Operation......................................................................... 113
16. UART
Figure 16.1. UART Block Diagram ......................................................................... 117
Table 16.1. UART Modes ....................................................................................... 118
Figure 16.2. UART Mode 0 Interconnect................................................................ 118
Figure 16.3. UART Mode 0 Timing Diagram .......................................................... 118
Figure 16.4. UART Mode 1 Timing Diagram .......................................................... 119
Figure 16.5. UART Modes 1, 2, and 3 Interconnect Diagram ................................ 120
Figure 16.6. UART Modes 2 and 3 Timing Diagram .............................................. 121
Figure 16.7. UART Multi-Processor Mode Interconnect Diagram .......................... 122
Table 16.2. Oscillator Frequencies for Standard Baud Rates ................................ 122
17. Timers
Figure 17.1. T0 Mode 0 Block Diagram.................................................................. 126
Figure 17.2. T0 Mode 2 Block Diagram.................................................................. 127
Figure 17.3. T0 Mode 3 Block Diagram.................................................................. 128
Figure 17.4. T2 Mode 0 Block Diagram.................................................................. 134
Figure 17.5. T2 Mode 1 Block Diagram.................................................................. 135
Figure 17.6. T2 Mode 2 Block Diagram.................................................................. 136
18. JTAG
8
Rev. 1.7
C8051F2xx
List of Registers
SFR Definition 5.1. AMX0SL: AMUX Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . 34
SFR Definition 5.2. ADC0CF: ADC Configuration Register . . . . . . . . . . . . . . . . . . . . . 35
SFR Definition 5.3. ADC0CN: ADC Control (C8051F220/1/6 and C8051F206) . . . . . . 36
SFR Definition 5.4. ADC0H: ADC Data Word (‘F220/1/6 and ‘F206) . . . . . . . . . . . . . 37
SFR Definition 5.5. ADC0GTH: ADC Greater-Than Data (‘F220/1/6 and ‘F206) . . . . . 37
SFR Definition 5.6. ADC0LTH: ADC Less-Than Data Byte (‘F220/1/6 and ‘F206) . . . . 37
SFR Definition 6.1. AMX0SL: AMUX Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . 42
SFR Definition 6.2. ADC0CF: ADC Configuration (‘F220/1/6 and ‘F206) . . . . . . . . . . . 43
SFR Definition 6.3. ADC0CN: ADC Control (‘F220/1/6 and ‘F206) . . . . . . . . . . . . . . . 44
SFR Definition 6.4. ADC0H: ADC Data Word MSB (C8051F206) . . . . . . . . . . . . . . . . 45
SFR Definition 6.5. ADC0L: ADC Data Word LSB (C8051F206) . . . . . . . . . . . . . . . . 45
SFR Definition 6.6. ADC0GTH: ADC Greater-Than Data High Byte (C8051F206) . . . 46
SFR Definition 6.7. ADC0GTL: ADC Greater-Than Data Low Byte (C8051F206) . . . . 46
SFR Definition 6.8. ADC0LTH: ADC Less-Than Data High Byte (C8051F206) . . . . . . 46
SFR Definition 6.9. ADC0LTL: ADC Less-Than Data Low Byte (C8051F206) . . . . . . . 47
SFR Definition 7.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 8.1. CPT0CN: Comparator 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 55
SFR Definition 8.2. CPT1CN: Comparator 1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 56
SFR Definition 9.1. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
SFR Definition 9.2. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
SFR Definition 9.3. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
SFR Definition 9.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 9.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 9.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 9.7. SWCINT: Software Controlled Interrupt Register . . . . . . . . . . . . . 75
SFR Definition 9.8. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
SFR Definition 9.9. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
SFR Definition 9.10. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . 79
SFR Definition 9.11. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . . . 80
SFR Definition 9.12. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . . 81
SFR Definition 9.13. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 9.14. PCON: Power Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . 84
SFR Definition 10.1. PSCTL: Program Store RW Control . . . . . . . . . . . . . . . . . . . . . . 88
SFR Definition 10.2. FLSCL: Flash Memory Timing Prescaler . . . . . . . . . . . . . . . . . . . 89
SFR Definition 10.3. FLACL: Flash Access Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
SFR Definition 11.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . . 90
SFR Definition 12.1. WDTCN: Watchdog Timer Control . . . . . . . . . . . . . . . . . . . . . . . 94
SFR Definition 12.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 13.1. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 13.2. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 14.1. PRT0MX: Port I/O MUX Register 0 . . . . . . . . . . . . . . . . . . . . . . 103
SFR Definition 14.2. PRT1MX: Port I/O MUX Register 1 . . . . . . . . . . . . . . . . . . . . . . 104
SFR Definition 14.3. PRT2MX: Port I/O MUX Register 2 . . . . . . . . . . . . . . . . . . . . . . 104
Rev. 1.7
9
C8051F2xx
SFR Definition 14.4. P0: Port0 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
SFR Definition 14.5. PRT0CF: Port0 Configuration Register . . . . . . . . . . . . . . . . . . . 105
SFR Definition 14.6. P0MODE: Port0 Digital/Analog Input Mode . . . . . . . . . . . . . . . . 106
SFR Definition 14.7. P1: Port1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
SFR Definition 14.8. PRT1CF: Port1 Configuration Register . . . . . . . . . . . . . . . . . . . 106
SFR Definition 14.9. P1MODE: Port1 Digital/Analog Input Mode . . . . . . . . . . . . . . . . 107
SFR Definition 14.10. P2: Port2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 14.11. PRT2CF: Port2 Configuration Register . . . . . . . . . . . . . . . . . . 107
SFR Definition 14.12. P2MODE: Port2 Digital/Analog Input Mode . . . . . . . . . . . . . . . 108
SFR Definition 14.13. P3: Port3 Register* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
SFR Definition 14.14. PRT3CF: Port3 Configuration Register* . . . . . . . . . . . . . . . . . 108
SFR Definition 14.15. P3MODE: Port3 Digital/Analog Input Mode* . . . . . . . . . . . . . . 109
SFR Definition 15.1. SPI0CFG: SPI Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
SFR Definition 15.2. SPI0CN: SPI Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
SFR Definition 15.3. SPI0CKR: SPI Clock Rate Register . . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 15.4. SPI0DAT: SPI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 16.1. SBUF: Serial (UART) Data Buffer . . . . . . . . . . . . . . . . . . . . . . . 123
SFR Definition 16.2. SCON: Serial Port Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
SFR Definition 17.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
SFR Definition 17.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
SFR Definition 17.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
SFR Definition 17.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
SFR Definition 17.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
SFR Definition 17.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
SFR Definition 17.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
SFR Definition 17.8. T2CON: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 17.9. RCAP2L: Timer 2 Capture Register Low Byte . . . . . . . . . . . . . . 138
SFR Definition 17.10. RCAP2H: Timer 2 Capture Register High Byte . . . . . . . . . . . . 138
SFR Definition 17.11. TL2: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 17.12. TH2: Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
JTAG Register Definition 18.1. IR: JTAG Instruction . . . . . . . . . . . . . . . . . . . . . . . . . 139
JTAG Register Definition 18.2. FLASHCON: JTAG Flash Control . . . . . . . . . . . . . . . 141
JTAG Register Definition 18.3. FLASHADR: JTAG Flash Address . . . . . . . . . . . . . . 141
JTAG Register Definition 18.4. FLASHDAT: JTAG Flash Data . . . . . . . . . . . . . . . . . 142
JTAG Register Definition 18.5. FLASHSCL: JTAG Flash Scale . . . . . . . . . . . . . . . . . 142
JTAG Register Definition 18.6. DEVICEID: JTAG Device ID . . . . . . . . . . . . . . . . . . . 143
10
Rev. 1.7
C8051F2xx
1.
System Overview
The C8051F2xx is a family of fully integrated, mixed-signal System on a Chip MCU's available with a true
12-bit ('F206) multi-channel ADC, 8-bit multi-channel ADC ('F220/1/6 and 'F206), or without an ADC
('F230/1/6). Each model features an 8051-compatible microcontroller core with 8 kB of Flash memory.
There are also UART and SPI serial interfaces implemented in hardware (not "bit-banged" in user software). Products in this family feature 22 or 32 general purpose I/O pins, some of which can be used for
assigned digital peripheral interface. Any pins may be configured for use as analog input to the analog-todigital converter ('F220/1/6 and 'F206 only). (See the Product Selection Guide in Table 1.1 for a quick reference of each MCUs' feature set.)
Other features include an on-board VDD monitor, WDT, and clock oscillator. On-board Flash memory can
be reprogrammed in-circuit, and may also be used for non-volatile data storage. Integrated peripherals
can also individually shut down any or all of the peripherals to conserve power. All parts have 256 bytes of
SRAM. Also, an additional 1024 bytes of RAM is available in the 'F206/226/236.
On-board JTAG debug support allows non-intrusive (uses no on-chip resources), full speed, in-circuit
debug using the production MCU installed in the final application. This debug system supports inspection
and modification of memory and registers, setting breakpoints, watchpoints, single stepping, run and halt
commands. All analog and digital peripherals are fully functional when emulating using JTAG.
Each MCU is specified for 2.7 to 3.6 V operation over the industrial temperature range (–45 to +85 °C) and
is available in the 48-pin TFQP and 32-pin LFQP. The Port I/Os are tolerant for input signals up to 5 V.
Flash Memory
RAM
SPI
UART
Timers (16-bit)
Digital Port I/O’s
ADC Resolution (bits)
ADC Max Speed (ksps)
ADC Inputs
Voltage Comparators
Package
C8051F206-GQ
C8051F220-GQ
C8051F221-GQ
C8051F226-GQ
C8051F230-GQ*
C8051F231-GQ*
C8051F236-GQ*
MIPS (Peak)
Table 1.1. Product Selection Guide
25
25
25
25
25
25
25
8k
8k
8k
8k
8k
8k
8k
1280
256
256
1280
256
256
1280
3
3
3
3
3
3
3
32
32
22
32
32
22
32
12
8
8
8
—
—
—
100
100
100
100
—
—
—
32
32
22
32
—
—
—
2
2
2
2
2
2
2
48TQFP
48TQFP
32LQFP
48TQFP
48TQFP
32LQFP
48TQFP
*Note: Not recommended for new designs.
Rev. 1.7
11
C8051F2xx
Figure 1.1. C8051F206, C8051F220 and C8051F226 Block Diagram (48 TQFP)
12
Rev. 1.7
C8051F2xx
Figure 1.2. C8051F221 Block Diagram (32 LQFP)
Rev. 1.7
13
C8051F2xx
Figure 1.3. C8051F230 and C8051F236 Block Diagram (48 TQFP)
14
Rev. 1.7
C8051F2xx
Figure 1.4. C8051F231 Block Diagram (32 LQFP)
1.1.
CIP-51TM Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051F206, C8051F220/1/6 and C8051F230/1/6 utilize Silcon Labs’ proprietary CIP-51 microcontroller core. The CIP-51 is fully compatible with the MCS-51TM instruction set. Standard 803x/805x assemblers and compilers can be used to develop software. The core contains the peripherals included with a
standard 8052, including three 16-bit counter/timers, a full-duplex UART, 256 bytes of internal RAM, an
optional 1024 bytes of XRAM, 128 byte Special Function Register (SFR) address space, and four bytewide I/O Ports.
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 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 number of instructions versus the system clock cycles to
execute them is as follows:
Instructions
26
50
5
14
7
3
1
2
1
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Rev. 1.7
15
C8051F2xx
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. Figure 1.5
shows a comparison of peak throughputs of various 8-bit microcontroller cores with their maximum system
clocks.
Figure 1.5. Comparison of Peak MCU Throughputs
1.1.3. Additional Features
The C8051F206, C8051F220/1/6 and C8051F230/1/6 have several key enhancements both inside and
outside the CIP-51 core to improve overall performance and ease of use in end applications.
The extended interrupt handler provides 22 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), allowing the 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.
There are up to six reset sources for the MCU: an on-board VDD monitor, a Watchdog Timer, a missing
clock detector, a voltage level detection from Comparator 0, a forced software reset, and an external reset
pin. The RST pin is bi-directional, accommodating an external reset, or allowing the internally generated
reset to be output on the RST pin. The on-board VDD monitor is enabled by pulling the MONEN pin high
(digital 1). The user may disable each reset source except for the VDD monitor and Reset Input Pin from
software. The watchdog timer may be permanently enabled in software after a power-on reset during
MCU initialization.
The MCU has an internal, stand-alone clock generator that is used by default as the system clock after
reset. If desired, the clock source may be switched "on the fly" to the external oscillator, which can use a
crystal, ceramic resonator, capacitor, RC, or external clock source to generate the system clock. This 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 (up to 16MHz) internal oscillator as needed.
16
Rev. 1.7
C8051F2xx
Figure 1.6. Comparison of Peak MCU Throughputs
1.2.
On-Board 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. An optional 1024 bytes of XRAM is available on the 'F206,
'F226 and 'F236. 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 or 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.
The MCU's program memory consists of 8 k + 128 bytes of Flash. This memory may be reprogrammed insystem in 512 byte sectors, and requires no special off-chip programming voltage. The 512 bytes from
addresses 0x1E00 to 0x1FFF are reserved for factory use. There is also a user programmable 128-byte
sector at address 0x2000 to 0x207F, which may be useful as a table for storing software constants, nonvolatile configuration information, or as additional program space. See Figure 1.7 for the MCU system memory map.
Rev. 1.7
17
C8051F2xx
Figure 1.7. On-Board Memory Map
1.3.
JTAG
The C8051F2xx have on-chip JTAG and debug logic that provide non-intrusive, full speed, in-circuit debug
using the production part installed in the end application using the four-pin JTAG I/F. The C8051F2xxDK is
a development kit with all the hardware and software necessary to develop application code and perform
in-circuit debug with the C8051F2xx. The kit includes software with a developer's studio and debugger, an
integrated 8051 assembler, and an RS-232 to JTAG interface module referred to as the EC. It also has a
target application board with a C8051F2xx installed and large prototyping area, plus the RS-232 and JTAG
cables, and wall-mount power supply. The Development Kit requires a Windows OS (Windows 95 or later)
computer with one available RS-232 serial port. As shown in Figure 1.8, the PC is connected via RS-232
to the EC. A six-inch ribbon cable connects the EC to the user's application board, picking up the four
JTAG pins and VDD and GND. The EC takes its power from the application board. It requires roughly
20 mA at 2.7–3.6 V. For applications where there is not sufficient power available from the target board,
the provided power supply can be connected directly to the EC.
This is a vastly superior configuration for developing and debugging embedded applications compared to
standard MCU Emulators, which use on-board "ICE Chips" and target cables and require the MCU in the
application board to be socketed. Silicon Labs' debug environment both increases ease of use, and preserves the performance of the precision analog peripherals.
18
Rev. 1.7
C8051F2xx
Figure 1.8. Degub Environment Diagram
1.4.
Digital/Analog Configurable I/O
The standard 8051 Ports (0, 1, 2, and 3) are available on the device. The ports behave like standard 8051
ports with a few enhancements.
Each port pin can be configured as either a push-pull or open-drain output. Any input that is configured as
an analog input will have its corresponding weak pull-up turned off.
Digital resources (timers, SPI, UART, system clock, and comparators) are routed to corresponding I/O pins
by configuring the port multiplexer. Port multiplexers are programmed by setting bits in SFR's (please see
Section 14). Any of the 32 external port pins may be configured as either analog inputs or digital I/O (See
Figure 1.9), so effectively, all port pins are dual function.
Rev. 1.7
19
C8051F2xx
Figure 1.9. Port I/O Functional Block Diagram
1.5.
Serial Ports
The C8051F206, C8051F220/1/6 and C8051F230/1/6 include a Full-Duplex UART and SPI Bus. Each of
the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus
requiring very little intervention by the CPU. The serial buses do not have to "share" resources such as
timers, interrupts, or Port I/O, so both of the serial buses may be used simultaneously. (You may use Timer1, Timer 2, or SYSCLK to generate baud rates for UART).
1.6.
Analog to Digital Converter
The C8051F220/1/6 has an on-chip 8-bit SAR ADC and the C8051F206 has a 12-bit SAR ADC with a programmable gain amplifier. With a maximum throughput of 100ksps, the ADC offers true 8-bit with an INL of
±1/4 LSB, and or 12-bit accuracy with ±2 LSB. The voltage reference can be the power supply (VDD), or
an external reference voltage (VREF). Also, the system controller can place the ADC into a power-saving
shutdown mode when not in use. A programmable gain amplifier follows the analog multiplexer. The gain
can be set in software from 0.5 to 16 in powers of 2.
Conversions can be initiated in two ways; a software command or an overflow on Timer 2. This flexibility
allows the start of conversion to be triggered by software events, or convert continuously. A completed
conversion causes an interrupt, or a status bit can be polled in software to determine the end of conversion. The resulting 8-bit data word is latched into an SFR upon completion of a conversion.
20
Rev. 1.7
C8051F2xx
ADC data is continuously monitored by a programmable window detector, which interrupts the CPU when
data is within the user-programmed window. This allows the ADC to monitor key system voltages in background mode, without the use of CPU resources.
Figure 1.10. ADC Diagram
1.7.
Comparators
The MCU's have two on-chip voltage comparators. The inputs of the comparators are available at package pins as illustrated in Figure 1.11. Each comparator's hysteresis is software programmable via special
function registers (SFR's). Both voltage level and positive/negative going symmetry can be easily programmed by the user. Additionally, comparator interrupts can be implemented on either rising or fallingedge output transitions. Please see 8.‘Comparators” on page 52 for details.
Rev. 1.7
21
C8051F2xx
Figure 1.11. Comparator Diagram
22
Rev. 1.7
C8051F2xx
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 Pin (except VDD and Port I/O) with
respect to DGND
–0.3
—
VDD +
0.3
V
Voltage on any Port I/O Pin or RST pins with respect to
DGND
–0.3
—
5.8
V
Voltage on VDD with respect to DGND
–0.3
4.2
V
Total Power Dissipation
—
1.0
800
W
Maximum Output Current Sunk by any Port pin
—
—
200
mA
Maximum Output Current Sunk by any other I/O pin
—
—
25
mA
Maximum Output Current Sourced by any Port pin
—
—
200
mA
Maximum Output Current Sourced by any other I/O pin
—
—
25
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. 1.7
23
C8051F2xx
3.
Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
2.7
3.0
3.6
V
Clock = 25 MHz
Clock = 1 MHz
Clock = 32 kHz
—
13
1.5
300
—
mA
mA
μA
Clock = 25 MHz
VDD supply current with ADC and
comparators active, and CPU inac- Clock = 1 MHz
Clock = 32 kHz
tive (Idle Mode)
—
9
1.8
275
—
mA
mA
μA
VDD supply current with ADC and
comparators inactive, and CPU
active
Clock = 25 MHz
Clock = 1 MHz
Clock = 32 kHz
—
12.5
1.0
25
—
mA
mA
μA
Digital Supply Current with CPU
inactive (Idle Mode)
Clock = 25 MHz
Clock = 1 MHz
Clock = 32 kHz
—
8.5
1.4
25
—
mA
mA
μA
Digital Supply Current (Stop Mode), Oscillator not running
VDD monitor enabled
—
10
—
μA
Digital Supply Current (Stop Mode), Oscillator not running
VDD monitor disabled
—
0.1
—
μA
Digital Supply RAM Data Retention
Voltage
—
1.5
—
V
–40
—
+85
°C
25
MHz
Analog Supply Voltage1
VDD supply current with ADC and
comparators active, and CPU
active
Specified Operating Temperature
Range
SYSCLK (system clock
frequency)2
0
Tsysl (SYSCLK low time)
18
—
—
ns
Tsysh (SYSCLK high time)
18
—
—
ns
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK must be at least 32 kHz to enable debugging.
24
Rev. 1.7
—
C8051F2xx
4.
Pinout and Package Definitions
Table 4.1. Pin Definitions
Name
VDD
‘F206,
F220,
226,
230,
236
‘F221,
231
Type
Description
48-Pin 32-Pin
11,31
8
Digital Voltage Supply.
GND
5,6,8,
13,32
9
MONEN
12
TCK
TMS
TDI
25
26
28
17
18
20
D In
D In
D In
TDO
27
19
D Out
XTAL1
9
6
A In
XTAL2
10
7
A Out
RST
14
10
D I/O
VREF
7
5
A I/O
CP0+
CP0CP0
CP1+
CP1CP1
P0.0/TX
4
3
2
1
48
47
40
4
3
2
1
32
31
28
P0.1/RX
39
27
P0.2/INT0
38
26
A In
A In
D Out
A In
A In
D Out
D I/O
A In
D I/O
A In
D I/O
A In
D In
Ground. (Note: Pins 5,6, and 8 on the 48-pin package are not
connected (NC), but it is recommended that they be connected to
ground.)
Monitor Enable (on 48 pin package ONLY). Enables reset voltage monitor function when pulled high (logic “1”).
JTAG Test Clock with internal pull-up.
JTAG Test-Mode Select with internal pull-up.
JTAG Test Data Input with internal pull-up. TDI is latched on a
rising edge of TCK.
JTAG Test Data Output. Data is shifted out on TDO on the falling
edge of TCK. TDO output is a tri-state driver.
Crystal Input. This pin is the return for the internal oscillator circuit for a crystal or ceramic resonator. For a precision internal
clock, connect a crystal or ceramic resonator from XTAL1 to
XTAL2. If overdriven by an external CMOS clock, this becomes
the system clock.
Crystal Output. This pin is the excitation driver for a crystal or
ceramic resonator.
Chip Reset. Open-drain output of internal Voltage Supply monitor. Is driven low when VDD is < 2.7V and MONEN=1, or when a
‘1’is written to PORSF. An external source can force a system
reset by driving this pin low.
Voltage Reference. When configured as an input, this pin is the
voltage reference for the ADC. Otherwise, VDD will be the reference. NOTE: this pin is Not Connected (NC) on ‘F230/1/6.
Comparator 0 Non-Inverting Input.
Comparator 0 Inverting Input.
Comparator 0 Output
Comparator 1 Non-Inverting Input.
Comparator 1 Inverting Input.
Comparator 1 Output
Port0 Bit0. (See the Port I/O Sub-System section for complete
description).
Port0 Bit1. (See the Port I/O Sub-System section for complete
description).
Port0 Bit2. (See the Port I/O Sub-System section for complete
description).
Rev. 1.7
25
C8051F2xx
Table 4.1. Pin Definitions (Continued)
Name
P0.3/INT1
P0.4/T0
P0.5/T1
P0.6/T2
‘F206,
F220,
226,
230,
236
‘F221,
231
48-Pin 32-Pin
37
25
D I/O
A In
36
24
D I/O
A In
35
23
D I/O
A In
34
22
D I/O
A In
P0.7/T2EX
33
21
P1.0/CP0+
4
4
P1.1/CP0-
3
3
P1.2/CP0
2
2
P1.3/CP1+
1
1
P1.4/CP1-
48
32
P1.5/CP1
47
31
P1.6/SYSCLK
46
30
P1.7
45
29
P2.0/SCK
24
16
P2.1/MISO
23
15
P2.2/MOSI
22
14
P2.3/NSS
21
13
P2.4
15
11
P2.5
16
12
P2.6
17
26
Type
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
D I/O
A In
Description
Port0 Bit3. (See the Port I/O Sub-System section for complete
description).
Port0 Bit4. (See the Port I/O Sub-System section for complete
description).
Port0 Bit5. (See the Port I/O Sub-System section for complete
description).
Port0 Bit6. (See the Port I/O Sub-System section for complete
description).
Port0 Bit7. (See the Port I/O Sub-System section for complete
description).
Port1 Bit0. (See the Port I/O Sub-System section for complete
description).
Port1 Bit1. (See the Port I/O Sub-System section for complete
description).
Port1 Bit2. (See the Port I/O Sub-System section for complete
description).
Port1 Bit3. (See the Port I/O Sub-System section for complete
description).
Port1 Bit4. (See the Port I/O Sub-System section for complete
description).
Port1 Bit5. (See the Port I/O Sub-System section for complete
description).
Port1 Bit6. (See the Port I/O Sub-System section for complete
description).
Port1 Bit7. (See the Port I/O Sub-System section for complete
description).
Port2 Bit0. (See the Port I/O Sub-System section for complete
description).
Port2 Bit1. (See the Port I/O Sub-System section for complete
description).
Port2 Bit2. (See the Port I/O Sub-System section for complete
description).
Port2 Bit3. (See the Port I/O Sub-System section for complete
description).
Port2 Bit4. (See the Port I/O Sub-System section for complete
description).
Port2 Bit5. (See the Port I/O Sub-System section for complete
description).
Port2 Bit6. (See the Port I/O Sub-System section for complete
description).
Rev. 1.7
C8051F2xx
Table 4.1. Pin Definitions (Continued)
Name
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
‘F206,
F220,
226,
230,
236
‘F221,
231
Type
48-Pin 32-Pin
18
D I/O
A In
44
D I/O
A In
43
D I/O
A In
42
D I/O
A In
41
D I/O
A In
30
D I/O
A In
29
D I/O
A In
20
D I/O
A In
19
D I/O
A In
Description
Port2 Bit7. (See the Port I/O Sub-System section for complete
description).
Port3 Bit0. (See the Port I/O Sub-System section for complete
description).
Port3 Bit1. (See the Port I/O Sub-System section for complete
description).
Port3 Bit2. (See the Port I/O Sub-System section for complete
description).
Port3 Bit3. (See the Port I/O Sub-System section for complete
description).
Port3 Bit4. (See the Port I/O Sub-System section for complete
description).
Port3 Bit5. (See the Port I/O Sub-System section for complete
description).
Port3 Bit6. (See the Port I/O Sub-System section for complete
description).
Port3 Bit7. (See the Port I/O Sub-System section for complete
description).
Rev. 1.7
27
C8051F2xx
Figure 4.1. TQFP-48 Pin Diagram
28
Rev. 1.7
C8051F2xx
Figure 4.2. LQFP-32 Pin Diagram
Rev. 1.7
29
C8051F2xx
Figure 4.3. TQFP-48 Package Drawing
30
Rev. 1.7
C8051F2xx
Figure 4.4. LQFP-32 Package Drawing
Rev. 1.7
31
C8051F2xx
5.
ADC (8-Bit, C8051F220/1/6 Only)
Description
The ADC subsystem for the C8051F220/1/6 consists of configurable analog multiplexer (AMUX), a programmable gain amplifier (PGA), and a 100ksps, 8-bit successive-approximation-register ADC with integrated track-and-hold and programmable window detector (see Figure 5.1). The AMUX, PGA, Data
Conversion Modes, and Window Detector are all configurable under software control via the Special Function Register's shown in Figure 5.1. The ADC subsystem (ADC, track-and-hold and PGA) is enabled only
when the ADCEN bit in the ADC Control register (ADC0CN, SFR Definition 5.3) is set to 1. The ADC subsystem is in low power shutdown when this bit is 0.
Figure 5.1. 8-Bit ADC Functional Block Diagram
5.1.
Analog Multiplexer and PGA
Any external port pin (ports 0-3) may be selected via software. The AMX0SL SFR is used to select the
desired analog input pin. (See SFR Definition 5.1). When the AMUX is enabled, the user selects which
port is to be used (bits PRTSL0-1), and then the pin in the selected port (bits PINSL0-2) to be the analog
input.
The table in ?? shows AMUX functionality by channel for each possible configuration. The PGA amplifies
the AMUX output signal by an amount determined by the states of the AMPGN2-0 bits in the ADC Configuration register, ADC0CF (SFR Definition 5.2). The PGA can be software-programmed for gains of 0.5, 1,
2, 4, 8 or 16. It defaults to a gain of 1 on reset.
32
Rev. 1.7
C8051F2xx
5.2.
ADC Modes of Operation
The ADC has a maximum conversion speed of 100ksps. The ADC conversion clock is derived from the
system clock. The ADC conversion clock is derived from a divided version of SYSCLK. Divide ratios of
1,2,4,8, or 16 are supported by setting the ADCSC bits in the ADC0CF Register. This is useful to adjust
conversion speed to accommodate different system clock speeds.
A conversion can be initiated in one of two ways, depending on the programmed states of the ADC Start of
Conversion Mode bits (ADSTM1, ADSTM0) in ADC0CN. Conversions may be initiated by:
1. Writing a 1 to the ADBUSY bit of ADC0CN;
2. A Timer 2 overflow (i.e., timed continuous conversions).
Writing a 1 to ADBUSY provides software control of the ADC whereby conversions are performed "ondemand". During conversion, the ADBUSY bit is set to 1 and restored to 0 when conversion is complete.
The falling edge of ADBUSY triggers an interrupt (when enabled) and sets the ADCINT interrupt flag in the
ADC0CN register. Note: When conversions are performed "on-demand", the ADCINT flag, not ADBUSY,
should be polled to determine when the conversion has completed. Converted data is available in the ADC
data word register, ADC0H.
The ADCTM bit in register ADC0CN controls the ADC track-and-hold mode. In its default state, the ADC
input is continuously tracked, except when a conversion is in progress. Setting ADCTM to 1 allows one of
two different low power track-and-hold modes to be specified by states of the ADSTM1-0 bits (also in
ADC0CN):
1. Tracking begins with a write of 1 to ADBUSY and lasts for 3 SAR clocks;
2. Tracking starts with an overflow of Timer 2 and lasts for 3 SAR clocks.
Tracking can be disabled (shutdown) when the entire chip is in low power standby or sleep modes.
Figure 5.2. 12-Bit ADC Track and Conversion Example Timing
Rev. 1.7
33
C8051F2xx
SFR Definition 5.1. AMX0SL: AMUX Channel Select
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
AMXEN
PRTSL1
PRTSL0
PINSL2
PINSL1
PINSL0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBB
Bits 7–6: UNUSED. Read = 00b; Write = don't care
Bit 5:
AMXEN enable
0: AMXEN disabled and port pins are unavailable for analog use.
1: AMXEN enabled to use/select port pins for analog use.
Bits 4–3: PRTSL1–0: Port Select Bits*.
00: Port0 select to configure pin for analog input from this port.
01: Port1 select to configure pin for analog input from this port.
10: Port2 select to configure pin for analog input from this port.
11: Port3 select to configure pin for analog input from this port.
Bits 2–0:PINSL2–0: Pin Select Bits
000: Pin 0 of selected port (above) to be used for analog input.
001: Pin 1 of selected port (above) to be used for analog input.
010: Pin 2 of selected port (above) to be used for analog input.
011: Pin 3 of selected port (above) to be used for analog input.
100: Pin 4 of selected port (above) to be used for analog input.
101: Pin 5 of selected port (above) to be used for analog input.
110: Pin 6 of selected port (above) to be used for analog input.
111: Pin 7 of selected port (above) to be used for analog input.
* Selecting a port for analog input does NOT default all pins of that port as analog input. After selecting a port for analog input, a pin must be selected using pin select bits (PINSL2–0). For example,
after setting the AMXEN to ‘1’, setting PRTSL1–0 to “11”, and setting PINSL2–0 to “100” P3.4 is
configured as analog input. All other Port 3 pins remain as GPIO pins. Also note that in order to use
a port pin as analog input, its input mode should be set to analog. Please see section 14.2.
34
Rev. 1.7
C8051F2xx
SFR Definition 5.2. ADC0CF: ADC Configuration Register
R/W
R/W
R/W
R/W
R/W
ADCSC2
ADCSC1
ADCSC0
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
AMPGN2 AMPGN1 AMPGN0
Bit2
Bit1
Bit0
Reset Value
01100000
SFR Address:
0xBC
Bits7–5: ADCSC2–0: ADC SAR Conversion Clock Period Bits
000: SAR Conversion Clock = 1 System Clock
001: SAR Conversion Clock = 2 System Clocks
010: SAR Conversion Clock = 4 System Clocks
011: SAR Conversion Clock = 8 System Clocks
1xx: SAR Conversion Clock = 16 Systems Clocks
NOTE: SAR conversion clock should be less than or equal to 2MHz.
Bits4–3: UNUSED. Read = 00b; Write = don’t care
Bits2–0: AMPGN2–0: ADC Internal Amplifier Gain
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
11x: Gain = 0.5
Rev. 1.7
35
C8051F2xx
SFR Definition 5.3. ADC0CN: ADC Control (C8051F220/1/6 and C8051F206)
R/W
R/W
ADCEN
ADCTM
Bit7
Bit6
R/W
R/W
R/W
R/W
R/W
ADCINT ADBUSY ADSTM1 ADSTM0 ADWINT
Bit5
Bit4
Bit3
Bit7:
Bit2
Bit1
R/W
Reset Value
ADLJST
00000000
Bit0
SFR Address:
(bit addressable)
0xE8
ADCEN: ADC Enable Bit
0: ADC Disabled. ADC is in low power shutdown.
1: ADC Enabled. ADC is active and ready for data conversions.
Bit6:
ADCTM: ADC Track Mode Bit
0: When the ADC is enabled, tracking is continuous unless a conversion is in process
1: Tracking Defined by ADSTM1-0 bits
ADSTM1-0:
00: Tracking starts with the write of 1 to ADBUSY and lasts for 3 SAR clocks
01: RESERVED
10: RESERVED
11: Tracking started by the overflow of Timer 2 and last for 3 SAR clocks
Bit5:
ADCINT: ADC Conversion Complete Interrupt Flag (cleared by software).
0: ADC has not completed a data conversion since the last time this flag was cleared
1: ADC has completed a data conversion
Bit4:
ADBUSY: ADC Busy Bit
Read
0: ADC Conversion complete or no valid data has been converted since a reset. The falling
edge of ADBUSY generates an interrupt when enabled.
1: ADC Busy converting data
Write
0: No effect
1: Starts ADC Conversion if ADSTM1-0 = 00b
Bits3–2: ADSTM1–0: ADC Start of Conversion Mode Bits
00: ADC conversion started upon a write of 1 to ADBUSY
01: RESERVED
10: RESERVED
11: ADC conversions initiated on overflows of Timer 2
Bit1:
ADWINT: ADC Window Compare Interrupt Flag
0: ADC Window Comparison Data match has not occurred
1: ADC Window Comparison Data match occurred
Bit0:
ADLJST: ADC Left Justify Data Bit (Used on C8051F206 only)
0: Data in ADC0H:ADC0L registers are right justified.
1: Data in ADC0H:ADC0L registers are left justified.
36
Rev. 1.7
C8051F2xx
SFR Definition 5.4. ADC0H: ADC Data Word (‘F220/1/6 and ‘F206)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
MSB
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
LSB
00000000
Bit0
SFR Address:
0xBF
Bits7–0: ADC Data Word Bits
EXAMPLE: ADC Data Word Conversion Map
AIN – GND(Volts)
REF x (255/256)
REF x ½
REF x (127/256)
0
5.3.
ADC0H
0xFF
0x80
0x7F
0x00
ADC Programmable Window Detector
The ADC programmable window detector is very useful in many applications. It continuously compares
the ADC output to user-programmed limits and notifies the system when an out-of-band 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 (ADWINT in ADC0CN)
can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC
Greater-Than and ADC Less-Than registers (ADC0GTH and ADC0LTH).
SFR Definition 5.5. ADC0GTH: ADC Greater-Than Data (‘F220/1/6 and ‘F206)
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:
0xC5
11111111
Bits7–0:
The high byte of the ADC Greater-Than Data Word.
SFR Definition 5.6. ADC0LTH: ADC Less-Than Data Byte (‘F220/1/6 and ‘F206)
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:
0xC7
00000000
Bits7–0:
The high byte of the ADC Less-Than Data Word.
Rev. 1.7
37
C8051F2xx
Given:
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0,
ADC0LTH = 0x20, ADC0GTH = 0x10.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x20 and > 0x10.
Given:
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0,
ADC0LTH = 0x10, ADC0GTH = 0x20.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x10 or > 0x20.
Figure 5.3. 8-Bit ADC Window Interrupt Examples
38
Rev. 1.7
C8051F2xx
Table 5.1. 8-Bit ADC Electrical Characteristics
VDD = 3.0 V, VREF = 2.40 V, PGA Gain = 1, –40 to +85 ×C unless otherwise specified.
Parameter
Conditions
Min
Typ
DC Accuracy
Resolution
—
8
Integral Nonlinearity
—
—
Differential Nonlinearity
Guaranteed Monotonic
—
—
Offset Error
2
—
Gain Error
2
—
Offset Temperature Coefficient
0.25
Dynamic Performance (10 kHz sine-wave input, 0 to –1 dB of full scale, 100 ksps)
Signal-to-Noise Plus Distortion
49.5
—
Up to the 5th harmonic
Max
Units
—
1/2
1/2
1/2
1/2
—
bits
LSB
LSB
LSB
LSB
ppm/C
—
dB
–60
–65
—
dB
—
–65
—
dB
16
1.5
—
—
—
—
—
—
2.5
—
100
clocks
MHz
μs
ksps
Input Voltage Range
0
—
VDD
V
Input Capacitance
Power Specifications
Power Supply Current
Power Supply Current in Shutdown
Power Supply Rejection
—
10
—
pF
—
—
—
0.45
0.1
0.3
1.0
1
—
mA
μA
mV/V
Total Harmonic Distortion
Spurious-Free Dynamic Range
Conversion Rate
Conversion Time in SAR Clocks
SAR Clock Frequency
Track/Hold Acquisition Time
Throughput Rate
Analog Inputs
Operating Mode, 100 ksps
Rev. 1.7
39
C8051F2xx
6.
ADC (12-Bit, C8051F206 Only)
Description
The ADC subsystem for the C8051F206 consists of configurable analog multiplexer (AMUX), a programmable gain amplifier (PGA), and a 100ksps, 12-bit successive-approximation-register ADC with integrated
track-and-hold and programmable window detector (see Figure 6.1). The AMUX, PGA, Data Conversion
Modes, and Window Detector are all configurable under software control via the Special Function Register's shown in Figure 6.1. The ADC subsystem (ADC, track-and-hold and PGA) is enabled only when the
ADCEN bit in the ADC Control register (ADC0CN, Figure 6.5) is set to 1. The ADC subsystem is in low
power shutdown when this bit is 0.
Figure 6.1. 12-Bit ADC Functional Block Diagram
6.1.
Analog Multiplexer and PGA
Any external port pin (ports 0-3) may be selected via software. The AMX0SL SFR is used to select the
desired analog input pin. (See SFR Definition 5.1). When the AMUX is enabled, the user selects which
port is to be used (bits PRTSL0–1), and then the pin in the selected port (bits PINSL0–2) to be the analog
input.
The PGA amplifies the AMUX output signal by an amount determined by the states of the AMPGN2–0 bits
in the ADC Configuration register, ADC0CF (SFR Definition 5.2). The PGA can be software-programmed
for gains of 0.5, 1, 2, 4, 8 or 16. It defaults to a gain of 1 on reset.
40
Rev. 1.7
C8051F2xx
6.2.
ADC Modes of Operation
The ADC has a maximum conversion speed of 100 ksps. The ADC conversion clock is derived from the
system clock. The ADC conversion clock is derived from a divided version of SYSCLK. Divide ratios of 1,
2, 4, 8, or 16 are supported by setting the ADCSC bits in the ADC0CF Register. This is useful to adjust
conversion speed to accommodate different system clock speeds.
A conversion can be initiated in one of two ways, depending on the programmed states of the ADC Start of
Conversion Mode bits (ADSTM1, ADSTM0) in ADC0CN. Conversions may be initiated by:
1. Writing a 1 to the ADBUSY bit of ADC0CN;
2. A Timer 2 overflow (i.e. timed continuous conversions).
Writing a 1 to ADBUSY provides software control of the ADC whereby conversions are performed "ondemand". During conversion, the ADBUSY bit is set to 1 and restored to 0 when conversion is complete.
The falling edge of ADBUSY triggers an interrupt (when enabled) and sets the ADCINT interrupt flag in the
ADC0CN register. Note: When conversions are performed "on-demand", the ADCINT flag, not ADBUSY,
should be polled to determine when the conversion has completed. Converted data is available in the ADC
data word register, ADC0H.
The ADCTM bit in register ADC0CN controls the ADC track-and-hold mode. In its default state, the ADC
input is continuously tracked, except when a conversion is in progress. Setting ADCTM to 1 allows one of
two different low power track-and-hold modes to be specified by states of the ADSTM1-0 bits (also in
ADC0CN):
1. Tracking begins with a write of 1 to ADBUSY and lasts for 3 SAR clocks;
2. Tracking starts with an overflow of Timer 2 and lasts for 3 SAR clocks.
Tracking can be disabled (shutdown) when the entire chip is in low power standby or sleep modes.
Figure 6.2. 12-Bit ADC Track and Conversion Example Timing
Rev. 1.7
41
C8051F2xx
SFR Definition 6.1. AMX0SL: AMUX Channel Select
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
AMXEN
PRTSL1
PRTSL0
PINSL2
PINSL1
PINSL0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBB
Bits 7–6:
UNUSED. Read = 00b; Write = don’t care
Bit 5:
AMXEN enable
0: AMXEN disabled and port pins are unavailable for analog use.
1: AMXEN enabled to use/select port pins for analog use.
Bits 4–3:
PRTSL1–0: Port Select Bits*.
00: Port0 select to configure pin for analog input from this port.
01: Port1 select to configure pin for analog input from this port.
10: Port2 select to configure pin for analog input from this port.
11: Port3 select to configure pin for analog input from this port.
Bits 2–0:PINSL2–0: Pin Select Bits
000: Pin 0 of selected port (above) to be used for analog input.
001: Pin 1 of selected port (above) to be used for analog input.
010: Pin 2 of selected port (above) to be used for analog input.
011: Pin 3 of selected port (above) to be used for analog input.
100: Pin 4 of selected port (above) to be used for analog input.
101: Pin 5 of selected port (above) to be used for analog input.
110: Pin 6 of selected port (above) to be used for analog input.
111: Pin 7 of selected port (above) to be used for analog input.
* Selecting a port for analog input does NOT default all pins of that port as analog input. After selecting a port for analog input, a pin must be selected using pin select bits (PINSL2–0). For example,
after setting the AMXEN to ‘1’, setting PRTSL1–0 to “11”, and setting PINSL2–0 to “100” P3.4 is
configured as analog input. All other Port 3 pins remain as GPIO pins. Also note that in order to use
a port pin as analog input, its input mode should be set to analog. Please see section 14.2.
42
Rev. 1.7
C8051F2xx
SFR Definition 6.2. ADC0CF: ADC Configuration (‘F220/1/6 and ‘F206)
R/W
R/W
R/W
R/W
R/W
ADCSC2
ADCSC1
ADCSC0
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
AMPGN2 AMPGN1 AMPGN0
Bit2
Bit1
Bit0
Reset Value
01100000
SFR Address:
0xBC
Bits7–5: ADCSC2–0: ADC SAR Conversion Clock Period Bits
000: SAR Conversion Clock = 1 System Clock
001: SAR Conversion Clock = 2 System Clocks
010: SAR Conversion Clock = 4 System Clocks
011: SAR Conversion Clock = 8 System Clocks
1xx: SAR Conversion Clock = 16 Systems Clocks
NOTE: SAR conversion clock should be less than or equal to 2MHz.
Bits4–3: UNUSED. Read = 00b; Write = don't care
Bits2–0: AMPGN2–0: ADC Internal Amplifier Gain
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
1x: Gain = 0.5
Rev. 1.7
43
C8051F2xx
SFR Definition 6.3. ADC0CN: ADC Control (‘F220/1/6 and ‘F206)
R/W
R/W
ADCEN
ADCTM
Bit7
Bit6
R/W
R/W
R/W
R/W
R/W
ADCINT ADBUSY ADSTM1 ADSTM0 ADWINT
Bit5
Bit4
Bit3
Bit7:
Bit2
Bit1
R/W
Reset Value
ADLJST
00000000
Bit0
SFR Address:
(bit addressable)
0xE8
ADCEN: ADC Enable Bit
0: ADC Disabled. ADC is in low power shutdown.
1: ADC Enabled. ADC is active and ready for data conversions.
Bit6:
ADCTM: ADC Track Mode Bit
0: When the ADC is enabled, tracking is continuous unless a conversion is in process
1: Tracking Defined by ADSTM1–0 bits
ADSTM1–0:
00: Tracking starts with the write of 1 to ADBUSY and lasts for 3 SAR clocks
01: RESERVED
10: RESERVED
11: Tracking started by the overflow of Timer 2 and last for 3 SAR clocks
Bit5:
ADCINT: ADC Conversion Complete Interrupt Flag (cleared by software).
0: ADC has not completed a data conversion since the last time this flag was cleared
1: ADC has completed a data conversion
Bit4:
ADBUSY: ADC Busy Bit
Read
0: ADC Conversion complete or no valid data has been converted since a reset. The falling
edge of ADBUSY generates an interrupt when enabled.
1: ADC Busy converting data
Write
0: No effect
1: Starts ADC Conversion if ADSTM1–0 = 00b
Bits3–2: ADSTM1–0: ADC Start of Conversion Mode Bits
00: ADC conversion started upon a write of 1 to ADBUSY
01: RESERVED
10: RESERVED
11: ADC conversions initiated on overflows of Timer 2
Bit1:
ADWINT: ADC Window Compare Interrupt Flag
0: ADC Window Comparison Data match has not occurred
1: ADC Window Comparison Data match occurred
Bit0:
ADLJST: ADC Left Justify Data Bit
0: Data in ADC0H:ADC0L registers are right justified.
1: Data in ADC0H:ADC0L registers are left justified.
44
Rev. 1.7
C8051F2xx
SFR Definition 6.4. ADC0H: ADC Data Word MSB (C8051F206)
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:
0xBF
Bits7–0: ADC Data Word Bits
For ADLJST = 1: Upper 8-bits of the 12-bit ADC Data Word.
For ADLJST = 0: Bits7–4 are the sign extension of Bit3. Bits 3–0 are the upper 4-bits of the
12-bit ADC Data Word.
SFR Definition 6.5. ADC0L: ADC Data Word LSB (C8051F206)
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:
0xBE
Bits7–0: ADC Data Word Bits
For ADLJST = 1: Bits7–4 are the lower 4-bits of the 12-bit ADC Data Word. Bits3–0 will
always read 0.
For ADLJST = 0: Bits7–0 are the lower 8-bits of the 12-bit ADC Data Word.
NOTE: Resulting 12-bit ADC Data Word appears in the ADC Data Word Registers as follows:
ADC0H[3:0]:ADC0L[7:0], if ADLJST = 0
(ADC0H[7:4] will be sign extension of ADC0H.3 if a differential reading, otherwise = 0000b)
ADC0H[7:0]:ADC0L[7:4], if ADLJST = 1
(ADC0L[3:0] = 0000b)
EXAMPLE: ADC Data Word Conversion Map, AIN0 Input in Single-Ended Mode
(AMX0CF=0x00, AMX0SL=0x00)
AIN0 – AGND (Volts)
REF x (4095/4096)
REF x ½
REF x (2047/4096)
0
ADC0H:ADC0L
(ADLJST = 0)
0x0FFF
0x0800
0x07FF
0x0000
ADC0H:ADC0L
(ADLJST = 1)
0xFFF0
0x8000
0x7FF0
0x0000
Rev. 1.7
45
C8051F2xx
6.3.
ADC Programmable Window Detector
The ADC programmable window detector is very useful in many applications. It continuously compares
the ADC output to user-programmed limits and notifies the system when an out-of-band 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 (ADWINT in ADC0CN)
can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC
Greater-Than and ADC Less-Than registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL).
Figure 6.3 and Figure 6.4 show example comparisons for reference. Notice that the window detector flag
can be asserted when the measured data is inside or outside the user-programmed limits, depending on
the programming of the ADC0GTx and ADC0LTx registers.
SFR Definition 6.6. ADC0GTH: ADC Greater-Than Data High Byte (C8051F206)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC5
Bits7–0:
The high byte of the ADC Greater-Than Data Word.
SFR Definition 6.7. ADC0GTL: ADC Greater-Than Data Low Byte (C8051F206)
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:
0xC4
11111111
Bits7–0:
The low byte of the ADC Greater-Than Data Word.
Definition: ADC Greater-Than Data Word = ADC0GTH:ADC0GTL
SFR Definition 6.8. ADC0LTH: ADC Less-Than Data High Byte (C8051F206)
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:
0xC4
11111111
Bits7–0:
The high byte of the ADC Less-Than Data Word.
46
Rev. 1.7
C8051F2xx
SFR Definition 6.9. ADC0LTL: ADC Less-Than Data Low Byte (C8051F206)
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:
0xC4
11111111
Bits7–0:
These bits are the low byte of the ADC Less-Than Data Word.
Definition:
ADC Less-Than Data Word = ADC0LTH:ADC0LTL
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0,
ADC0LTH:ADC0LTL
=
0x0200,
ADC0GTH:ADC0GTL = 0x0100.
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0,
ADC0LTH:ADC0LTL
=
0x0100,
ADC0GTH:ADC0GTL = 0x0200.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x0200 and >
0x0100.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x0100 or >
0x0200.
Figure 6.3. 12-Bit ADC Window Interrupt Examples, Right Justified Data
Rev. 1.7
47
C8051F2xx
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 1,
ADC0LTH:ADC0LTL
=
0x2000,
ADC0GTH:ADC0GTL = 0x1000.
AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 1,
ADC0LTH:ADC0LTL
=
0x1000,
ADC0GTH:ADC0GTL = 0x2000.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x2000 and >
0x1000.
An ADC End of Conversion will cause an ADC
Window Compare Interrupt (ADWINT=1) if the
resulting ADC Data Word is < 0x1000 or >
0x2000.
Figure 6.4. 12-Bit ADC Window Interrupt Examples, Left Justified Data
48
Rev. 1.7
C8051F2xx
Table 6.1. 12-Bit ADC Electrical Characteristics (C8015F206 only)
VDD = 3.0 V, VREF = 2.40 V (REFBE=0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
DC Accuracy
Resolution
12
Integral Nonlinearity
—
1
Differential Nonlinearity
Guaranteed Monotonic
—
—
Offset Error
20
5
Full Scale Error
Differential mode
—
—
Offset Temperature Coefficient
—
0.25
Dynamic Performance (10 kHz sine-wave input, 0 to –1 dB of full scale, 100 ksps)
Signal-to-Noise Plus Distortion
63
66
Total Harmonic Distortion
Up to the
5th
harmonic
Spurious-Free Dynamic Range
Conversion Rate
Conversion Time in SAR Clocks
SAR Clock Frequency
Track/Hold Acquisition Time
Throughput Rate
Analog Inputs
Voltage Conversion Range
Input Voltage
Input Capacitance
Power Specifications
Power Supply Current
(VDD supplied to ADC)
Any pin (in Analog Input Mode)
Operating Mode, 100 ksps
Power Supply Rejection
Rev. 1.7
Max
Units
2
2
—
–2010
—
bits
LSB
LSB
LSB
LSB
ppm/C
—
dB
–60
–72
—
dB
60
76
—
dB
16
—
1.5
—
—
—
—
—
—
2.0
—
100
clocks
MHz
s
ksps
0
—
V
GND
—
VREF
VDD
—
10
—
pF
—
0.45
1.0
mA
—
0.3
—
mV/V
V
49
C8051F2xx
7.
Voltage Reference (C8051F206/220/221/226)
The voltage reference circuit selects between an externally connected reference and the power supply
voltage (VDD). (See Figure 7.1).
An external reference can be connected to the VREF pin and selected by setting the REF0CN special
function register per Figure 7.1. The external reference supply must be between VDD – 0.3 V and 1 V. VDD
may also be selected using REF0CN per SFR Definition 7.1. The electrical specifications for the Voltage
Reference are given in Table 7.1.
Figure 7.1. Voltage Reference Functional Block Diagram
SFR Definition 7.1. REF0CN: Reference Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
-
-
-
-
-
-
REFSL1
REFSL0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD1
Bits7–2: UNUSED. Read = 00000b; Write = don't care
Bit1–0:
50
REFSL1– REFSL0: Voltage reference selection.
Bits control which reference is selected.
00: External VREF source is selected.
01: Reserved.
10: Reserved.
11: VDD selected as VREF source.
Rev. 1.7
Reset Value
C8051F2xx
Table 7.1. Reference Electrical Characteristics
VDD = 3.0 V, Temperature –40 to +85 ×C
External Reference ([REFSL1: REFSL0] = 00), VREF = 2.4 V)
Min
Typ
Max
Units
Input Voltage Range
1.00
—
(VDD) – 0.3 V
V
Input Current
Input Resistance
—
100
0.1
—
10
—
μA
M
Rev. 1.7
51
C8051F2xx
8.
Comparators
The MCU has two on-board voltage comparators as shown in Figure 8.1. The inputs of each Comparator
are available at the package pins. The output of each comparator is optionally available at port1 by configuring (see Section 14). When assigned to package pins, each comparator output can be programmed to
operate in open drain or push-pull modes (see section 14.2).
The hysteresis of each comparator is software-programmable via its respective Comparator Control Register (CPT0CN, CPT1CN). The user can program both the amount of hysteresis voltage (referred to the
input voltage) and the positive-going and negative-going symmetry of this hysteresis around the threshold
voltage. The output of the comparator can be polled in software, or can be used as an interrupt source.
Each comparator can be individually enabled or disabled (shutdown). When disabled, the comparator output (if assigned to a Port I/O pin via the Port1 MUX) defaults to the logic low state and its interrupt capability is suspended. Comparator inputs can be externally driven from –0.25 V to (VDD) + 0.25 V without
damage or upset.
The Comparator 0 hysteresis is programmed using bits 3–0 in the Comparator 0 Control Register CPT0CN
(shown in SFR Definition 8.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. As shown in Figure 8.2, settings of 10, 4 or 2 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 CP0HYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section 9.4). The CP0FIF flag is set upon a Comparator 0 falling-edge
interrupt, and the CP0RIF flag is set upon the Comparator 0 rising-edge interrupt. Once set, these bits
remain set until cleared by the user software. The Output State of Comparator 0 can be obtained at any
time by reading the CP0OUT bit. Comparator 0 is enabled by setting the CP0EN bit, and is disabled by
clearing this bit. Note there is a 20 mS power on time between setting CP0EN and the output stabilizing.
Comparator 0 can also be programmed as a reset source. For details, see Section 11. The operation of
Comparator 1 is identical to that of Comparator 0, except the Comparator 1 is controlled by the CPT1CN
Register (SFR Definition 8.2). Also, Comparator 1 can not be programmed as a reset source. The complete electrical specifications for the Comparators are given in Table 8.1.
52
Rev. 1.7
C8051F2xx
Figure 8.1. Comparator Functional Block Diagram
Rev. 1.7
53
C8051F2xx
Figure 8.2. Comparator Hysteresis Plot
54
Rev. 1.7
C8051F2xx
SFR Definition 8.1. CPT0CN: Comparator 0 Control
R/W
R
R/W
R/W
CP0EN
CP0OUT
CP0RIF
CP0FIF
Bit7
Bit6
Bit5
Bit4
Bit7:
Bit6:
Bit5:
Bit4:
Bit3–2:
Bit1–0:
R/W
R/W
R/W
R/W
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address:
0x9E
CP0EN: Comparator 0 Enable Bit
0: Comparator 0 Disabled.
1: Comparator 0 Enabled.
CP0OUT: Comparator 0 Output State Flag
0: Voltage on CP0+ < CP0–
1: Voltage on CP0+ > CP0–
CP0RIF: Comparator 0 Rising-Edge Interrupt Flag
0: No Comparator 0 Rising-Edge Interrupt has occurred since this flag was cleared
1: Comparator 0 Rising-Edge Interrupt has occurred since this flag was cleared
CP0FIF: Comparator 0 Falling-Edge Interrupt Flag
0: No Comparator 0 Falling-Edge Interrupt has occurred since this flag was cleared
1: Comparator 0 Falling-Edge Interrupt has occurred since this flag was cleared
CP0HYP1–0: Comparator 0 Positive Hysteresis Control Bits
00: Positive Hysteresis Disabled
01: Positive Hysteresis = 2 mV
10: Positive Hysteresis = 4 mV
11: Positive Hysteresis = 10 mV
CP0HYN1–0: Comparator 0 Negative Hysteresis Control Bits
00: Negative Hysteresis Disabled
01: Negative Hysteresis = 2 mV
10: Negative Hysteresis = 4 mV
11: Negative Hysteresis = 10 mV
Rev. 1.7
55
C8051F2xx
SFR Definition 8.2. CPT1CN: Comparator 1 Control
R/W
R
R/W
R/W
CP1EN
CP1OUT
CP1RIF
CP1FIF
Bit7
Bit6
Bit5
Bit4
Bit7:
Bit6:
Bit5:
Bit4:
Bit3–2:
Bit1–0:
56
R/W
R/W
R/W
R/W
CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address:
0x9F
CP1EN: Comparator 1 Enable Bit
0: Comparator 1 Disabled.
1: Comparator 1 Enabled.
CP1OUT: Comparator 1 Output State Flag
0: Voltage on CP1+ < CP1–
1: Voltage on CP1+ > CP1–
CP1RIF: Comparator 1 Rising-Edge Interrupt Flag
0: No Comparator 1 Rising-Edge Interrupt has occurred since this flag was cleared
1: Comparator 1 Rising-Edge Interrupt has occurred since this flag was cleared
CP1FIF: Comparator 1 Falling-Edge Interrupt Flag
0: No Comparator 1 Falling-Edge Interrupt has occurred since this flag was cleared
1: Comparator 1 Falling-Edge Interrupt has occurred since this flag was cleared
CP1HYP1–0: Comparator 1 Positive Hysteresis Control Bits
00: Positive Hysteresis Disabled
01: Positive Hysteresis = 2 mV
10: Positive Hysteresis = 4 mV
11: Positive Hysteresis = 10 mV
CP1HYN1–0: Comparator 1 Negative Hysteresis Control Bits
00: Negative Hysteresis Disabled
01: Negative Hysteresis = 2 mV
10: Negative Hysteresis = 4 mV
11: Negative Hysteresis = 10 mV
Rev. 1.7
C8051F2xx
Table 8.1. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 ×C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Response Time1*
(CP+) – (CP–) = 100 mV
—
4
—
μs
Response Time2*
(CP+) – (CP–) = 10 mV
—
12
—
μs
—
1.5
4
mV/V
Common Mode Rejection
Ratio
Positive Hysteresis1
CPnHYP1-0 = 00
—
0
1
mV
Positive Hysteresis2
CPnHYP1-0 = 01
2
4.5
7
mV
Positive Hysteresis3
CPnHYP1-0 = 10
4
9
15
mV
Positive Hysteresis4
CPnHYP1-0 = 11
10
17
25
mV
Negative Hysteresis1
CPnHYN1-0 = 00
—
0
1
mV
Negative Hysteresis2
CPnHYN1-0 = 01
2
4.5
7
mV
Negative Hysteresis3
CPnHYN1-0 = 10
4
9
15
mV
Negative Hysteresis4
CPnHYN1-0 = 11
10
17
25
mV
–0.25
—
(VDD)
+ 0.25
V
Input Capacitance
—
7
—
pF
Input Bias Current
–5
0.001
+5
nA
Input Offset Voltage
–10
—
+10
mV
—
20
—
μs
—
0.1
1
mV/V
—
1.5
4
μA
Inverting or Non-inverting
Input Voltage Range
POWER SUPPLY
Power-up Time
CPnEN from 0 to 1
Power Supply Rejection
Supply Current
Operating Mode
(each comparator) at DC
*Note: CPnHYP1-0 = CPnHYN1-0 = 00.
Rev. 1.7
57
C8051F2xx
9.
CIP-51 Microcontroller
General Description
The MCU’s system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51TM instruction set. Standard 803x/805x assemblers and compilers can be used to develop software. The MCU has a superset of all the peripherals included with a standard 8051. Included are three
16-bit counter/timers (see description in Section 17), a full-duplex UART (see description in Section 16),
256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (see Section 9.3),
and four byte-wide I/O Ports (see description in Section 14). The CIP-51 also includes on-chip debug
hardware (see description in Section 18), and interfaces directly with the MCU’s analog and digital subsystems providing a complete data acquisition or control-system solution in a single integrated circuit.
Features
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 9.1 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
Optional 1024 Bytes of XRAM
8 kB Flash Program Memory
•
•
•
•
•
•
Four Byte-Wide I/O Ports
Extended Interrupt Handler
Reset Input
Power Management Modes
On-chip Debug Circuitry
Program and Data Memory Security
Figure 9.1. CIP-51 Block Diagram
58
Rev. 1.7
C8051F2xx
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 12MHz. 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 25MHz, it has a peak throughput of 25MIPS. The CIP-51 has
a total of 109 instructions. The number of instructions versus the system clock cycles required to execute
them is as follows:
Instructions
26
50
5
14
7
3
1
2
1
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Programming and Debugging Support
A JTAG-based serial interface is provided for in-system programming of the Flash program memory and
communication with on-chip debug support logic. 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 circuitry facilitates full speed in-circuit debugging, allowing the setting of hardware breakpoints and watchpoints, 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 and noninvasive, requiring no RAM, Stack, timers, or other on-chip resources.
The CIP-51 is supported by development tools from Silicon Laboratories and third party vendors. Silicon
Labs provides an integrated development environment (IDE) including editor, macro assembler, debugger
and programmer. The IDE’s debugger and programmer interface to the CIP-51 via its JTAG interface to
provide fast and efficient in-system device programming and debugging. Third party macro assemblers
and C compilers are also available.
Rev. 1.7
59
C8051F2xx
9.1.
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.
9.1.1. 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 9.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
9.1.2. MOVX Instruction and Program Memory
The MOVX instruction is typically used to access external data memory. The CIP-51 does not support
external data or program memory. In the CIP-51, the MOVX instruction accesses the on-chip program
memory space implemented as re-programmable Flash memory and the 1024 bytes of XRAM (optionally
available on ‘F226/236 and ‘F206). This 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) and Section 11 (External RAM) for further details.
Table 9.1. CIP-51 Instruction Set Summary
Mnemonic
Arithmetic Operations
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
60
Description
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
Rev. 1.7
Bytes
Clock
Cycles
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
C8051F2xx
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
INC @Ri
DEC A
DEC Rn
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
DA A
Logical Operations
ANL A,Rn
ANL A,direct
ANL A,@Ri
ANL A,#data
ANL direct,A
ANL direct,#data
ORL A,Rn
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
Data Transfer
MOV A,Rn
MOV A,direct
MOV A,@Ri
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
1
1
1
2
1
1
1
1
1
Clock
Cycles
2
1
1
2
2
1
4
8
1
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
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
1
2
1
2
2
3
1
2
1
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
1
2
2
2
2
3
1
2
2
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
Move register to A
Move direct byte to A
Move indirect RAM to A
1
2
1
1
2
2
Description
Rev. 1.7
Bytes
61
C8051F2xx
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
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
XCH A,@Ri
XCHD A,@Ri
Boolean Manipulation
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
62
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
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 data pointer 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
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
1
Clock
Cycles
2
1
2
2
2
2
3
2
3
2
2
2
3
3
3
3
3
3
3
2
2
1
2
2
2
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
1
2
1
2
1
2
2
2
2
2
2
2
2
1
2
1
2
1
2
2
2
2
2
2
2
2/3
Description
Rev. 1.7
Bytes
C8051F2xx
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
JNC rel
JB bit,rel
JNB bit,rel
JBC bit,rel
Program Branching
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
Jump if carry not set
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
2
3
3
3
Clock
Cycles
2/3
3/4
3/4
3/4
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
2
3
1
1
2
3
2
1
2
2
3
3
3
3
2
3
1
3
4
5
5
3
4
3
3
2/3
2/3
3/4
3/4
3/4
4/5
2/3
3/4
1
Description
Rev. 1.7
Bytes
63
C8051F2xx
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0–R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through register R0–R1
rel - 8-bit, signed (two’s compliment) 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
#data 16 - 16-bit constant
bit - Direct-addressed bit in Data RAM or SFR.
addr 11 - 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.
addr 16 - 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.
64
Rev. 1.7
C8051F2xx
9.2.
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. There are 256 bytes of internal data
memory and 8 kB of internal program memory address space implemented within the CIP-51. The CIP-51
memory organization is shown in Figure 9.2.
9.2.1. Program Memory
The CIP-51 has a 8 kB program memory space. The MCU implements 8320 bytes of this program memory space as in-system, reprogrammable Flash memory, organized in a contiguous block from addresses
0x0000 to 0x207F. Note: 512 bytes (0x1E00 – 0x1FFF) of this memory are reserved for factory use and
are not available for user program storage.
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 for further details.
9.2.2. Data Memory
The CIP-51 implements 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 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 bit 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 will
access the upper 128 bytes of data memory. Figure 9.2 illustrates the data memory organization of the
CIP-51.
Additionally, the C8051F206/226/236 feature 1024 Bytes of RAM mapped in the external data memory
space. All address locations may be accessed using the MOVX instruction. (Please see Section 11).
Rev. 1.7
65
C8051F2xx
Figure 9.2. Memory Map
9.2.3. 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 9.4). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing
modes use registers R0 and R1 as index registers.
9.2.4. 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 bit 7 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, 22h.3
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the user Carry flag.
66
Rev. 1.7
C8051F2xx
9.2.5. 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.
The MCU also has built-in hardware for a stack record. The stack record is a 32-bit shift register, where
each Push or increment SP pushes one record bit onto the register, and each Call pushes two record bits
onto the register. (A Pop or decrement SP pops one record bit, and a Return pops two record bits, also.)
The stack record circuitry can also detect an overflow or underflow on the 32-bit shift register, and can
notify the emulator software even with the MCU running full-speed debug.
Rev. 1.7
67
C8051F2xx
9.3.
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 9.3 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, P1, SCON, 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 9.3, for a detailed description of each register.
Table 9.2. Special Function Register Memory Map
F8
SPI0CN
WDTCN
F0
B
E8
ADC0CN1
P0MODE
E0
D8
D0
C8
ACC
PRT0MX
PSW
T2CON
REF0CN
P1MODE
2
P2MODE P3MODE
PRT1MX
PRT2MX
RCAP2L
RCAP2H
C0
IP
B0
P3
A8
IE
A0
98
90
88
80
P2
SCON
P1
TCON
P0
0(8)
Bit Addressable
EIE1
TL2
OSCXCN
EIE2
TH2
ADC0GTH1 ADC0LTL4 ADC0LTH1
AMX0SL1 ADC0CF1
OSCICN
ADC0L4
FLSCL
ADC0H1
FLACL
EMI0CN3
PRT3CF
CPT1CN
SWCINT
PRT0CF
PRT1CF
SPI0CKR
PRT2CF
CPT0CN
TL1
DPH
TH0
TH1
CKCON
PSCTL
PCON
3(B)
4(C)
5(D)
6(E)
7(F)
SBUF
SPI0CFG
SPI0DAT
TMOD
SP
TL0
DPL
1(9)
2(A)
Notes:
1. C8051F230/1/6 Do not have these registers.
2. C8051F221/231 Does not have this register (32 pin package).
3. On the C8051F206 and C8051F226/236 only.
4. On the C8051F206 only (12-bit ADC)
68
EIP2
RSTSRC
ADC0GTL4
B8
EIP1
Rev. 1.7
C8051F2xx
Table 9.3. Special Function Registers
SFR’s are listed in alphabetical order.
Address
Register
0xE0
ACC
0xBC
ADC0CF
0xE8
ADC0CN
Description
Accumulator
ADC Configuration
ADC Control
Page No.
73
35
36
0xC5
ADC0GTH1
ADC Greater-Than Data Word (High Byte)
37
0xC4
ADC0GTL4
ADC Greater-Than Data Word (Low Byte)
46
0xBF
ADC0H1
ADC Data Word (High Byte)
37
0xBE
ADC0L4
ADC Data Word (Low Byte)
45
0xC7
ADC0LTH1
ADC Less-Than Data Word (High Byte)
46
0xCE
ADC0LTL4
AMX0SL
B
CKCON
CPT0CN
CPT1CN
DPH
DPL
EIE1
EIE2
EIP1
EIP2
ADC Less-Than Data Word (Low Byte)
47
ADC MUX Channel Selection
B Register
Clock Control
Comparator 0 Control
Comparator 1 Control
Data Pointer (High Byte)
Data Pointer (Low Byte)
Extended Interrupt Enable 1
Extended Interrupt Enable 2
External Interrupt Priority 1
External Interrupt Priority 2
34
73
131
55
56
71
71
79
80
81
82
External Memory Interface Control
90
0xB7
0xB6
0xA8
0xB8
EMI0CN3
FLACL
FLSCL
IE
IP
Flash Memory Read Limit
Flash Memory Timing Prescaler
Interrupt Enable
Interrupt Priority Control
89
89
77
78
0xB2
0xB1
0x80
0x90
0xA0
0xB0
0xF1
0xF2
0xF3
OSCICN
OSCXCN
P0
P1
P2
P3
P0MODE
P1MODE
P2MODE
Internal Oscillator Control
External Oscillator Control
Port 0 Latch
Port 1 Latch
Port 2 Latch
Port 3 Latch
Port0 Digital/Analog Output Mode
Port1 Digital/Analog Output Mode
Port2 Digital/Analog Output Mode
98
99
105
106
107
108
106
107
108
0xF4
P3MODE2
PCON
Port3 Digital/Analog Output Mode
109
Power Control
84
0xBB
0xF0
0x8E
0x9E
0x9F
0x83
0x82
0xE6
0xE7
0xF6
0xF7
0xAF
0x87
Rev. 1.7
69
C8051F2xx
Table 9.3. Special Function Registers (Continued)
SFR’s are listed in alphabetical order.
Address
Register
0xA4
PRT0CF
0xA5
PRT1CF
0xA6
PRT2CF
0xA7
PRT3CF
0xE1
PRT0MX
0xE2
PRT1MX
0xE3
PRT2MX
0x8F
PSCTL
0xD0
PSW
0xCB
RCAP2H
0xCA
RCAP2L
0xD1
REF0CN
0xEF
RSTSRC
0x99
SBUF
0x98
SCON
0x81
SP
0x9A
SPI0CFG
0x9D
SPI0CKR
0xF8
SPI0CN
0x9B
SPI0DAT
0xAD
SWCINT
0xC8
T2CON
0x88
TCON
0x8C
TH0
0x8D
TH1
0xCD
TH2
0x8A
TL0
0x8B
TL1
0xCC
TL2
0x89
TMOD
0xFF
WDTCN
0x84–86, 0x91–97, 0x9C, 0xA1–A3, 0xA9–
AC, 0xAE, 0xB3–B5, 0xB9–BA, 0xBD–
BE,0xC0–C4, 0xC6,0xCE–CF,0xD2–
DF,0xE9–EE,0xF5,0xF9–FE
Description
Port 0 Configuration
Port 1 Configuration
Port 2 Configuration
Port 3 Configuration
Port 0 Multiplexer I/O Configuration
Port 1 Multiplexer I/O Configuration
Port 2 Multiplexer I/O Configuration
Program Store RW Control
Program Status Word
Counter/Timer 2 Capture (High Byte)
Counter/Timer 2 Capture (Low Byte)
Voltage Reference Control Register
Reset Source Register
Serial Data Buffer (UART)
Serial Port Control (UART)
Stack Pointer
Serial Peripheral Interface Configuration
SPI Clock Rate
SPI Bus Control
SPI Port 1Data
Software Controlled Interrupt Register
Counter/Timer 2 Control
Counter/Timer Control
Counter/Timer 0 Data Word (High Byte)
Counter/Timer 1 Data Word (High Byte)
Counter/Timer 2 Data Word (High Byte)
Counter/Timer 0 Data Word (Low Byte)
Counter/Timer 1 Data Word (Low Byte)
Counter/Timer 2 Data Word (Low Byte)
Counter/Timer Mode
Watchdog Timer Control
Reserved
Notes:
1. C8051F230/1/6 Do not have these registers.
2. C8051F221/231 Does not have this register (32 pin package).
3. On the C8051F206 and C8051F226/236 only.
4. On the C8051F206 only (12-bit ADC)
70
Rev. 1.7
Page No.
105
106
107
108
103
104
104
88
72
138
138
50
95
123
124
71
114
116
115
116
75
137
129
132
132
138
132
132
138
130
94
C8051F2xx
9.3.1. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved
bits should be set to logic 0. 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 datasheet associated with their corresponding system function.
SFR Definition 9.1. 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:
0x81
00000111
Bits 7–0: 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.
SFR Definition 9.2. DPL: Data Pointer 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:
0x81
00000111
Bits 7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed RAM.
SFR Definition 9.3. 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:
0x81
00000111
Bits 7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed RAM.
Rev. 1.7
71
C8051F2xx
SFR Definition 9.4. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset Value
CY
AC
F0
RS1
RS0
OV
F1
PARITY
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit
0xD0
addressable)
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation results in a carry (addition) or a borrow
(subtraction). It is cleared to 0 by all other arithmetic operations.
Bit6:
AC: Auxiliary Carry Flag.
This bit is set when the last arithmetic operation results in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to 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
RS0
0
1
0
1
Register Bank
0
1
2
3
Address
0x00–0x07
0x08–0x0F
0x10–0x17
0x18–0x1F
Note: Any instruction which changes the RS1–RS0 bits must not be immediately followed by
the “MOV Rn, A” instruction.
Bit2:
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).
•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.
Bit1:
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
Bit0:
PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum
is even.
72
Rev. 1.7
C8051F2xx
SFR Definition 9.5. 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)
0xE0
Bits 7–0: ACC: Accumulator
This register is the accumulator for arithmetic operations.
SFR Definition 9.6. B: B Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
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)
0xF0
Bits 7–0: B: B Register
This register serves as a second accumulator for certain arithmetic operations.
Rev. 1.7
73
C8051F2xx
9.4.
Interrupt Handler
The CIP-51 includes an extended interrupt system supporting up to 22 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 interrupt-pending 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–EIE2). 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.
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)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
9.4.1. MCU Interrupt Sources and Vectors
The MCU allocates 9 interrupt sources to on-chip peripherals. 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. The
MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in
Table 9.4. 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).
9.4.2. External Interrupts
The two external interrupt sources (/INT0 and /INT1) are configurable as active-low level-sensitive or
active-low edge-sensitive inputs depending on the setting of IT0 (TCON.0) and IT1 (TCON.2). IE0
(TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flag 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 follows the state of the external interrupt's input pin.
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.
9.4.3. Software Controlled Interrupts
The C8051F2xx family of devices features four Software Controlled Interrupts controlled by flags located in
the Software Controlled Interrupt Flag Register (SWCINT). See SFR Definition 9.7. When a logic '1' is
written to a Software-Controlled Interrupt Flag, the CIP-51 will jump to an associated interrupt service vector (see Table 9.4, “Interrupt Summary,” on page 75). These interrupt flags must be cleared by software.
74
Rev. 1.7
C8051F2xx
SFR Definition 9.7. SWCINT: Software Controlled Interrupt Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SCI3
SCI2
SCI1
SCI0
-
-
-
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xAD
Bit7:
SCI3: Software Controlled Interrupt 3 Bit.
If enabled, writing a logic 1 to this interrupt control bit will cause the CPU to vector to the
SCI3 interrupt service routine. This bit is not cleared in hardware. It must be cleared by
software.
Bit6:
SCI2: Software Controlled Interrupt 2 Bit.
If enabled, writing a logic 1 to this interrupt control bit will cause the CPU to vector to the
SCI2 interrupt service routine. This bit is not cleared in hardware. It must be cleared by
software.
Bit5:
SCI1: Software Controlled Interrupt 1 Bit.
If enabled, writing a logic 1 to this interrupt control bit will cause the CPU to vector to the
SCI1 interrupt service routine. This bit is not cleared in hardware. It must be cleared by
software.
Bit4:
SCI0: Software Controlled Interrupt 0 Bit.
If enabled, writing a logic 1 to this interrupt control bit will cause the CPU to vector to the
SCI0 interrupt service routine. This bit is not cleared in hardware. It must be cleared by
software.
Bits3–0: UNUSED. Read = 0000b, Write = don't care.
Table 9.4. Interrupt Summary
Interrupt Source
Reset
External Interrupt 0 (/INT0)
Timer 0 Overflow
External Interrupt 1 (/INT1)
Timer 1 Overflow
Interrupt
Vector
0x0000
0x0003
0x000B
0x0013
0x001B
Serial Port (UART)
0x0023
Timer 2 Overflow (or EXF2)
0x002B
Serial Peripheral Interface
0x0033
ADC0 Window Comparison
Comparator 0 Falling Edge
Comparator 0 Rising Edge
Comparator 1 Falling Edge
Comparator 1 Rising Edge
0x0043
0x0053
0x005B
0x0063
0x006B
Priority
Interrupt-Pending Flag
Order
Top
None
0
IE0 (TCON.1)
1
TF0 (TCON.5)
2
IE1 (TCON.3)
3
TF1 (TCON.7)
RI (SCON.0)
4
TI (SCON.1)
5
TF2 (T2CON.7)
SPIF (SPI0STA.7)
WCOL (SPI0CN.6)
6
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
8
ADWINT (ADC0CN.2)
10
CP0FIF (CPT0CN.4)
11
CP0RIF (CPT0CN.5)
12
CP1FIF (CPT1CN.4)
13
CP1RIF (CPT1CN.5)
Rev. 1.7
Enable
Always enabled
EX0 (IE.0)
ET0 (IE.1)
EX1 (IE.2)
ET1 (IE.3)
ES (IE.4)
ET2 (IE.5)
ESPI0 (EIE1.0)
EWADC0 (EIE1.2)
ECP0F (EIE1.4)
ECP0R (EIE1.5)
ECP1F (EIE1.6)
ECP1R (EIE1.7)
75
C8051F2xx
Table 9.4. Interrupt Summary (Continued)
Interrupt Source
ADC0 End of Conversion
Software Controlled Interrupt 0
Software Controlled Interrupt 1
Software Controlled Interrupt 2
Software Controlled Interrupt 3
Unused Interrupt Location
External Crystal OSC Ready
Interrupt
Vector
0x007B
0x0083
0x008B
0x0093
0x009B
0x00A3
0x00AB
Priority
Interrupt-Pending Flag
Order
15
ADCINT (ADC0CN.5)
16
SCI0 (SWCINT.4)
17
SCI1 (SWCINT.5)
18
SCI2 (SWCINT.6)
19
SCI3 (SWCINT.7)
20
None
21
XTLVLD (OSCXCN.7)
Enable
EADC0 (EIE2.1)
ESCI0 (EIE2.2)
ESCI1 (EIE2.3)
ESCI2 (EIE2.4)
ESCI3 (EIE2.5)
Reserved (EIE2.6)
EXVLD (EIE2.7)
9.4.4. 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–EIP2) 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.
9.4.5. 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. NOTE: If a
Flash write or erase is performed, the MCU is stalled during the operation and interrupts will not be serviced until the operation is complete. 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.
76
Rev. 1.7
C8051F2xx
9.4.6. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. 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).
SFR Definition 9.8. IE: Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EA
-
ET2
ES
ET1
EX1
ET0
EX0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0xA8
Bit7:
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.
Bit6:
UNUSED. Read = 0, Write = don't care.
Bit5:
ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable all Timer 2 interrupts.
1: Enable interrupt requests generated by the TF2 flag (T2CON.7)
Bit4:
ES: Enable Serial Port (UART) Interrupt.
This bit sets the masking of the Serial Port (UART) interrupt.
0: Disable all UART interrupts.
1: Enable interrupt requests generated by the R1 flag (SCON.0) or T1 flag (SCON.1).
Bit3:
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupts.
1: Enable interrupt requests generated by the TF1 flag (TCON.7).
Bit2:
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 pin.
Bit1:
ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupts.
1: Enable interrupt requests generated by the TF0 flag (TCON.5).
Bit0:
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 pin.
Rev. 1.7
77
C8051F2xx
SFR Definition 9.9. IP: Interrupt Priority
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
PT2
PS
PT1
PX1
PT0
PX0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bits7–6: UNUSED. Read = 00b, Write = don't care.
Bit5:
PT2 Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupts.
0: Timer 2 interrupts set to low priority level.
1: Timer 2 interrupts set to high priority level.
Bit4:
PS: Serial Port (UART) Interrupt Priority Control.
This bit sets the priority of the Serial Port (UART) interrupts.
0: UART interrupts set to low priority level.
1: UART interrupts set to high priority level.
Bit3:
PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupts.
0: Timer 1 interrupts set to low priority level.
1: Timer 1 interrupts set to high priority level.
Bit2:
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupts.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
Bit1:
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupts.
0: Timer 0 interrupts set to low priority level.
1: Timer 0 interrupt set to high priority level.
Bit0:
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupts.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
78
Rev. 1.7
Bit0
SFR Address:
(bit addressable)
0xB8
C8051F2xx
SFR Definition 9.10. EIE1: Extended Interrupt Enable 1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ECP1R
ECP1F
ECP0R
ECP0F
-
EWADC0
-
ESPI0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE6
Bit7:
ECP1R: Enable Comparator 1 (CP1) Rising Edge Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 Rising Edge interrupt.
1: Enable interrupt requests generated by the CP1RIF flag (CPT1CN.3).
Bit6:
ECP1F: Enable Comparator 1 (CP1) Falling Edge Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 Falling Edge interrupt.
1: Enable interrupt requests generated by the CP1FIF flag (CPT1CN.4).
Bit5:
ECP0R: Enable Comparator 0 (CP0) Rising Edge Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 Rising Edge interrupt.
1: Enable interrupt requests generated by the CP0RIF flag (CPT0CN.3).
Bit4:
ECP0F: Enable Comparator 0 (CP0) Falling Edge Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 Falling Edge interrupt.
1: Enable interrupt requests generated by the CP0FIF flag (CPT0CN.4).
Bit3:
Reserved. Read = 0, Write = don't care.
Bit2:
EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 window compare interrupt.
0: Disable ADC0 Window Comparison Interrupt.
1: Enable Interrupt requests generated by ADC0 Window Comparisons.
Bit1:
Reserved. Read = 0, Write = don't care.
Bit0:
ESPI0: Enable Serial Peripheral Interface 0 Interrupt.
This bit sets the masking of SPI0 interrupt.
0: Disable all SPI0 interrupts.
1: Enable Interrupt requests generated by SPI0.
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SFR Definition 9.11. EIE2: Extended Interrupt Enable 2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EXVLD
-
ESCI3
ESCI2
ESCI1
ESCI0
EADC0
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE7
Bit7:
EXVLD: Enable External Clock Source Valid (XTLVLD) Interrupt.
This bit sets the masking of the XTLVLD interrupt.
0: Disable all XTLVLD interrupts.
1: Enable interrupt requests generated by the XTLVLD flag (OSCXCN.7)
Bit6:
Reserved. Must write 0. Reads 0.
Bit5:
ESCI3: Enable Software Controlled Interrupt 3.
This bit sets the masking of Software Controlled Interrupt 3.
0: Disable Software Controlled Interrupt 3.
1: Enable interrupt requests generated setting the Software Controlled Interrupt Bit 3.
Bit4:
ESCI2: Enable Software Controlled Interrupt 2.
This bit sets the masking of Software Controlled Interrupt 2.
0: Disable Software Controlled Interrupt 2.
1: Enable interrupt requests generated setting the Software Controlled Interrupt Bit 2.
Bit3:
ESCI1: Enable Software Controlled Interrupt 1.
This bit sets the masking of Software Controlled Interrupt 1.
0: Disable Software Controlled Interrupt 1.
1: Enable interrupt requests generated setting the Software Controlled Interrupt Bit 1.
Bit2:
ESCI0: Enable Software Controlled Interrupt 0.
This bit sets the masking of Software Controlled Interrupt 0.
0: Disable Software Controlled Interrupt 0.
1: Enable interrupt requests generated setting the Software Controlled Interrupt Bit 0.
Bit1:
EADC0: Enable ADC0 End of Conversion Interrupt.
This bit sets the masking of the ADC0 End of Conversion Interrupt.
0: Disable ADC0 Conversion Interrupt.
1: Enable interrupt requests generated by the ADC0 Conversion Interrupt.
Bit0:
Reserved. Read = 0, Write = don't care.
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SFR Definition 9.12. EIP1: Extended Interrupt Priority 1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PCP1R
PCP1F
PCP0R
PCP0F
-
PWADC0
-
PSPI0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF6
Bit7:
PCP1R: Comparator 1 (CP1) Rising Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 rising interrupt set to low priority level.
1: CP1 rising interrupt set to high priority level.
Bit6:
PCP1F: Comparator 1 (CP1) Falling Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 falling interrupt set to low priority level.
1: CP1 falling interrupt set to high priority level.
Bit5:
PCP0R: Comparator 0 (CP0) Rising Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 rising interrupt set to low priority level.
1: CP0 rising interrupt set to high priority level.
Bit4:
PCP0F: Comparator 0 (CP0) Falling Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 falling interrupt set to low priority level.
1: CP0 falling interrupt set to high priority level.
Bit3:
Reserved. Read = 0, Write = don't care.
Bit2:
PWADC0: Analog-to-Digital Converter 0 window compare (ADC0) Interrupt Priority Control.
This bit sets the priority of the ADC0 window compare interrupt.
0: ADC0 window compare interrupt set to low priority level.
1: ADC0 window compare interrupt set to high priority level.
Bit1:
UNUSED. Read = 0, Write = don't care.
Bit0:
PSPI0: Serial Peripheral Interface 0 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.
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SFR Definition 9.13. EIP2: Extended Interrupt Priority 2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PXVLD
-
PSCI3
PSCI2
PSCI1
PSCI0
PADC0
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF7
Bit7:
PXVLD: External Clock Source Valid (XTLVLD) Interrupt Priority Control.
This bit sets the priority of the XTLVLD interrupt.
0: XTLVLD interrupt set to low priority level.
1: XTLVLD interrupt set to high priority level.
Bit6:
Reserved. Must write 0. Reads 0.
Bit5:
PSCI3: Software Controlled Interrupt 3 Priority Control.
This bit sets the priority of the Software Controlled Interrupt 3.
0: External Interrupt 7 set to low priority level.
1: External Interrupt 7 set to high priority level.
Bit4:
PSCI2: Software Controlled Interrupt 2 Priority Control.
This bit sets the priority of the Software Controlled Interrupt 2.
0: Software Controlled Interrupt 2 set to low priority level.
1: Software Controlled Interrupt 2 set to high priority level.
Bit3:
PSCI1: Software Controlled Interrupt 1 Priority Control.
This bit sets the priority of the Software Controlled Interrupt 1.
0: Software Controlled Interrupt 1 set to low priority level.
1: Software Controlled Interrupt 1 set to high priority level.
Bit2:
PSCI0: Software Controlled Interrupt 0 Priority Control.
This bit sets the priority of the Software Controlled Interrupt 0.
0: Software Controlled Interrupt 0 set to low priority level.
1: Software Controlled Interrupt 0 set to high priority level.
Bit1:
PADC0: ADC End of Conversion Interrupt Priority Control.
This bit sets the priority of the ADC0 End of Conversion Interrupt.
0: ADC0 End of Conversion interrupt set to low priority level.
1: ADC0 End of Conversion interrupt set to high priority level.
Bit0:
Reserved. Read = 0, Write = don't care.
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9.5.
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 external peripherals and internal clocks active. In Stop mode, the CPU is
halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the system clock is
stopped. 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 9.14 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 put into low power mode. Turning
off the active oscillator saves even more power, but requires a reset to restart the MCU.
9.5.1. 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. 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 or RST is asserted. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU will 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.
Note: 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. Any instructions that set the IDLE bit should be followed by an instruction
that has 2 or more op-code bytes, for example:
// in ‘C’:
PCON |= 0x01;
PCON = PCON;
// set IDLE bit
// ... followed by a 3-cycle dummy instruction
; in assembly:
ORL PCON, #01h
MOV PCON, PCON
; set IDLE bit
; ... followed by a 3-cycle dummy instruction
If enabled, the 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 12.7 Watchdog Timer for more information
on the use and configuration of the WDT.
9.5.2. 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. In Stop mode, the CPU and oscillators are stopped, effectively shutting
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down all digital peripherals. Each analog peripheral must 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 sleep for longer than the MCD
timeout of 100sec.
SFR Definition 9.14. PCON: Power Control Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SMOD
GF4
GF3
GF2
GF1
GF0
STOP
IDLE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x87
Bit7:
SMOD: Serial Port Baud Rate Doubler Enable.
0: Serial Port baud rate is that defined by Serial Port Mode in SCON.
1: Serial Port baud rate is double that defined by Serial Port Mode in SCON.
Bits6–2: GF4–GF0: General Purpose Flags 4–0.
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: Goes into power down mode. (Turns off internal oscillator).
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: Goes into idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial
Ports, and Analog Peripherals are still active.)
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10. Flash Memory
This MCU includes 8 k + 128 bytes of on-chip, re-programmable Flash memory for program code and nonvolatile data storage. The Flash memory can be programmed in-system, a single byte at a time, through
the JTAG interface or by software using the MOVX instruction. Once cleared to 0, a Flash bit must be
erased to set it back to 1. The 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. The Flash memory is designed to withstand
at least 20,000 write/erase cycles. Refer to Table 10.1 for the electrical characteristics of the Flash memory.
10.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the JTAG 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 JTAG commands to program Flash memory, see Section 18.1.
The Flash memory can be programmed by software using the MOVX 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 setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic
1. Writing to Flash remains enabled until the PSWE bit is cleared by software.
To ensure the contents of the Flash contents, it is strongly recommended that the on-chip VDD monitor be
enabled (by tieing the MONEN pin 'high') in any application that writes and/or erases Flash memory from
software.
Writes to Flash memory can clear bits but cannot set them. Only an erase operation can set bits in Flash.
The byte location to be programmed must be erased before a new value can be written. The 8kbyte Flash
memory is organized in 512-byte sectors. The erase operation applies to an entire sector (setting all bytes
in the sector to 0xFF). Setting the PSEE Program Store Erase Enable bit (PSCTL.1) and PSWE Program
Store Write Enable bit (PSCTL.0) to logic 1 and then using the MOVX command to write a data byte to any
byte location within the sector will erase an entire 512-byte sector. The data byte written can be of any
value because it is not actually written to the Flash. Flash erasure remains enabled until the PSEE bit is
cleared by software. The following sequence illustrates the algorithm for programming the Flash memory
by software:
1.
2.
3.
4.
5.
6.
7.
Disable interrupts.
Enable Flash Memory write/erase in FLSCL Register using FLASCL bits.
Set PSEE (PSCTL.1) to enable Flash sector erase.
Set PSWE (PSCTL.0) to enable Flash writes.
Use MOVX to write a data byte to any location within the 512-byte sector to be erased.
Clear PSEE to disable Flash sector erase.
Use MOVX to write a data byte to the desired byte location within the erased 512-byte sector.
Repeat until finished. (Any number of bytes can be written from a single byte to and entire
sector.)
8. Clear the PSWE bit to disable Flash writes.
Write/Erase timing is automatically controlled by hardware based on the prescaler value held in the Flash
Memory Timing Prescaler register (FLSCL). The 4-bit prescaler value FLASCL determines the time interval for write/erase operations. The FLASCL value required for a given system clock is shown in SFR Definition 10.2, along with the formula used to derive the FLASCL values. When FLASCL is set to 1111b, the
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write/erase operations are disabled. Note that code execution in the 8051 is stalled while the Flash is
being programmed or erased.
Table 10.1. Flash Memory Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 ×C unless otherwise specified.
Parameter
Endurance
Erase/Write Cycle Time
Conditions
Min
20 k
—
Typ
100 k
10
Max
—
—
Units
Erase/Wr
ms
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
instruction and read using the MOVC instruction.
The MCU incorporates an additional 128-byte sector of Flash memory located at 0x2000 – 0x207F. This
sector can be used for program code or data storage. However, its smaller sector size makes it particularly
well suited as general purpose, non-volatile scratchpad memory. Even though Flash memory can be written a single byte at a time, an entire sector must be erased first. In order to change a single byte of a multibyte data set, the data must be moved to temporary storage. Next, the sector is erased, the data set
updated and the data set returned to the original sector. The 128-byte sector-size facilitates updating data
without wasting program memory space by allowing the use of internal data RAM for temporary storage. (A
normal 512-byte sector is too large to be stored in the 256-byte internal data memory.)
10.2. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as prevent the viewing of proprietary program code and constants. The Program Store Write
Enable (PSCTL.0) and the Program Store Erase Enable (PSCTL.1) bits protect the Flash memory from
accidental modification by software. These bits must be explicitly set to logic 1 before software can modify
the Flash memory. Additional security features prevent proprietary program code and data constants from
being read or altered across the JTAG interface or by software running on the system controller.
A set of security lock bytes stored at 0x1DFE and 0x1DFF protect the Flash program memory from being
read or altered across the JTAG interface. Each bit in a security lock-byte protects one 1 kB block of memory. Clearing a bit to logic 0 in a Read lock byte prevents the corresponding block of Flash memory from
being read across the JTAG interface. Clearing a bit in the Write/Erase lock byte protects the block from
JTAG erasures and/or writes. The Read lock byte is at location 0x1DFF. The Write/Erase lock byte is
located at 0x1DFE. Figure 10.1 shows the location and bit definitions of the security bytes. The 512-byte
sector containing the lock byte cannot be erased by software. Writing to the reserved area should not be
performed.
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Flash Read Lock Byte
Bits7–0: Each bit locks a corresponding block of memory. (Bit 7 is MSB.)
0: Read operations are locked (disabled) for corresponding block across the JTAG interface.
1: Read operations are unlocked (enabled) for corresponding block across the JTAG interface.
Flash Write/Erase Lock Byte
Bits7–0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG
interface.
1: Write/Erase operations are unlocked (enabled) for corresponding block across the
JTAG interface.
Flash Access Limit Register (FLACL)
The content of this register is used as the high byte of the 16-bit software read limit
address. The 16-bit read limit address value is calculated as 0xNN00 where NN is
replaced by content of this register on reset. Software running at or above this address is
prohibited from using the MOVX and MOVC instructions to read, write, or erase, locations
below this address. Any attempts to read locations below this limit will return the value
0x00.
Figure 10.1. Flash Program Memory Security Bytes
The lock bits can always be read and cleared to logic 0 regardless of the security setting applied to the
block containing the security bytes. This allows additional blocks to be protected after the block containing
the security bytes has been locked. However, the only means of removing a lock once set is to erase the
entire program memory space by performing a JTAG erase operation. NOTE: Erasing the Flash memory
block containing the security bytes will automatically initiate erasure of the entire program memory space
(except for the reserved area). This erasure can only be performed via the JTAG. If a non-security byte in
the 0x1C00–0x1DFF page is written to in order to perform an erasure of that page, then that page including
the security bytes will be erased.
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The Flash Access Limit security feature protects proprietary program code and data from being read by
software running on the CIP-51. This feature provides support for OEMs that wish to program the MCU
with proprietary value-added firmware before distribution. The value-added firmware can be protected
while allowing additional code to be programmed in remaining program memory space later.
The Software Read Limit (SRL) is a 16-bit address that establishes two logical partitions in the program
memory space. The first is an upper partition consisting of all the program memory locations at or above
the SRL address, and the second is a lower partition consisting of all the program memory locations starting at 0x0000 up to (but excluding) the SRL address. Software in the upper partition can execute code in
the lower partition, but is prohibited from reading locations in the lower partition using the MOVC instruction. (Executing a MOVC instruction from the upper partition with a source address in the lower partition
will always return a data value of 0x00.) Software running in the lower partition can access locations in
both the upper and lower partition without restriction.
The Value-added firmware should be placed in the lower partition. On reset, control is passed to the valueadded firmware via the reset vector. Once the value-added firmware completes its initial execution, it
branches to a predetermined location in the upper partition. If entry points are published, software running
in the upper partition may execute program code in the lower partition, but it cannot read the contents of
the lower partition. Parameters may be passed to the program code running in the lower partition either
through the typical method of placing them on the stack or in registers before the call or by placing them in
prescribed memory locations in the upper partition.
The SRL address is specified using the contents of the Flash Access Register. The 16-bit SRL address is
calculated as 0xNN00, where NN is the contents of the SRL Security Register. Thus, the SRL can be
located on 256-byte boundaries anywhere in program memory space. However, the 512-byte erase sector
size essentially requires that a 512 boundary be used. The contents of a non-initialized SRL security byte
is 0x00, thereby setting the SRL address to 0x0000 and allowing read access to all locations in program
memory space by default.
SFR Definition 10.1. PSCTL: Program Store RW 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 allows an entire page of the Flash program memory to be erased (provided
the PSWE bit is set to '1'). After setting this bit, 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
instruction. The location must be erased before writing data.
0: Write to Flash program memory disabled.
1: Write to Flash program memory enabled.
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SFR Definition 10.2. FLSCL: Flash Memory Timing Prescaler
R/W
R/W
R/W
R/W
FOSE
FRAE
-
-
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
FLASCL
Bit3
Bit2
Bit1
Reset Value
10001111
Bit0
SFR Address:
0xB6
Bit7:
FOSE: Flash One-Shot Timer Enable
0: Flash One-shot timer disabled.
1: Flash One-shot timer enabled
Bit6:
FRAE: Flash Read Always Enable
0: Flash reads per one-shot timer
1: Flash always in read mode
Bits5–4: UNUSED. Read = 00b, Write = don't care.
Bits3–0: FLASCL: Flash Memory Timing Prescaler.
This register specifies the prescaler value for a given system clock required to generate the
correct timing for Flash write/erase operations. If the prescaler is set to 1111b, Flash
write/erase operations are disabled.
0000: System Clock < 50 kHz
0001: 50 kHz < System Clock < 100 kHz
0010: 100 kHz < System Clock < 200 kHz
0011: 200 kHz < System Clock < 400 kHz
0100: 400 kHz < System Clock < 800 kHz
0101: 800 kHz < System Clock < 1.6 MHz
0110: 1.6 MHz < System Clock < 3.2 MHz
0111: 3.2 MHz < System Clock < 6.4 MHz
1000: 6.4 MHz < System Clock < 12.8 MHz
1001: 12.8 MHz < System Clock < 25.6 MHz
1010: 25.6 MHz < System Clock < 51.2 MHz*
1011, 1100, 1101, 1110: Reserved Values
1111: Flash Memory Write/Erase Disabled
The prescaler value is the smallest value satisfying the following equation:
FLASCL > log2(System Clock / 50kHz)
*For test purposes. The C8051F2xx is not guaranteed to operate over 25 MHz.
SFR Definition 10.3. FLACL: Flash Access Limit
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
Bits 7–0: FLACL: Flash Memory Access Limit.
This register holds the high byte of the 16-bit program memory read/write/erase limit
address. The entire 16-bit access limit address value is calculated as 0xNN00 where NN is
replaced by contents of FLACL. A write to this register sets the Flash Access Limit. Any
subsequent writes are ignored until the next reset.
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11. On-Chip XRAM (C8051F206/226/236)
The C8051F206/226/236 features 1024 Bytes of RAM mapped into the external data memory space. All
address locations may be accessed using the external move instruction (MOVX) and the data pointer
(DPTR), or using indirect MOVX addressing mode. If the MOVX instruction is used with an 8-bit operand
(such as @R1), then the high byte is the External Memory Interface Control Register (EMI0CN, shown in
SFR Definition 11.1). Addressing using 8 bits will map to one of four 256-byte pages, and these pages are
selected by setting the PGSEL bits in the EMI0CN register.
NOTE: The MOVX instruction is also used for write to the Flash memory. Please see section 10 for
details. The MOVX instruction will access XRAM by default.
For any of the addressing modes, 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 ("wrap around") over the entire 64k
of possible address values. For example, the XRAM byte at address 0x0000 is also at address 0x0400,
0x0800, 0x0C00, 0x1000, etc. This feature is useful when doing a linear memory fill, as the address
pointer does not have to be reset when reaching the RAM block boundary.
SFR Definition 11.1. EMI0CN: External Memory Interface Control
R
R
R
R
R
R
R/W
R/W
-
-
-
-
-
-
PGSEL1
PGSEL0
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xAF
Bits7–2: Not Used -read only 000000b
Bits1–0: XRAM Page Select Bits PGSEL[1:0]
The XRAM Page Select bits provide the high byte of the 16-bit external memory address
when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. The
upper 6 bits are "don't cares", so the 1k address blocks are repeated modulo over the entire
data memory address space.
00:0x000 – 0x0FF
01:0x100 – 0x1FF
10:0x200 – 0x2FF
11:0x300 – 0x3FF
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12. Reset Sources
The reset circuitry of the MCU allows the controller to be easily placed in a predefined default condition.
On entry to this reset state, the CIP-51 halts program execution, forces the external port pins to a known
state and initializes the SFRs to their defined reset values. Interrupts and timers are disabled. On exit, the
program counter (PC) is reset, and program execution starts at location 0x0000.
All of the SFRs are reset to predefined values. The reset values of the SFR bits are defined in the SFR
detailed descriptions. The contents of internal data memory are not changed during a reset and 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 are not altered.
The I/O port latches are reset to 0xFF (all logic ones), activating internal weak pull-ups which take the
external I/O pins to a high state. The weak pull-ups are enabled during and after the reset. If the source of
reset is from the VDD Monitor or writing a '1' to the PORSF bit, the RST pin is driven low until the end of the
VDD reset timeout.
On exit from the reset state, the MCU uses the internal oscillator running at 2MHz as the system clock by
default. Refer to Section 13 for information on selecting and configuring the system clock source. The
Watchdog Timer is enabled using its longest timeout interval. (Section 12.7 details the use of the Watchdog Timer.) Once the system clock source is stable, program execution begins at location 0x0000.
There are six sources for putting the MCU into the reset state: power-on/power-fail (VDD monitor), external
RST pin, software commanded, Comparator 0, Missing Clock Detector, and Watchdog Timer. Each reset
source is described below:
Figure 12.1. Reset Sources Diagram
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12.1. Power-on Reset
The CIP-51 incorporates a power supply monitor that holds the MCU in the reset state until VDD rises
above the VRST level during power-up. (See Figure 12.2 for timing diagram, and refer to Table 12.1 for
the Electrical Characteristics of the power supply monitor circuit.) The RST pin is asserted (low) until the
end of the 100msec VDD Monitor timeout in order to allow the VDD supply to become stable. On 48-pin
packages, the VDD monitor is enabled by pulling the MONEN pin high and is disabled by pulling the
MONEN pin low. The MONEN pin should never be left floating. On 32-pin packages, the VDD monitor is
always enabled and cannot be disabled.
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. 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.
12.2. Software Forced Reset
Writing a 1 to the PORSF bit forces a Power-On Reset as described in Section 12.1.
Figure 12.2. VDD Monitor Timing Diagram
12.3. Power-fail Reset
When the VDD monitor is enabled, the MONEN pin (not on C8051F221/F231 32 pin parts) is "pulled high",
and power-down transition or power irregularity causes VDD to drop below VRST, the power supply monitor
will drive the RST pin low and return the CIP-51 to the reset state (see Figure 12.2). When VDD returns to
a level above VRST, the CIP-51 will leave the reset state in the same manner as that for the power-on
reset. 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 is
set, the data may no longer be valid.
92
Rev. 1.7
C8051F2xx
12.4. External Reset
The external RST pin provides a means for external circuitry to force the CIP-51 into a reset state. Asserting an active-low signal on the RST pin will cause the CIP-51 to enter the reset state. Although there is a
weak pull-up, it may be desirable to provide an external pull-up and/or decoupling of the RST pin to avoid
erroneous noise-induced resets. The CIP-51 will remain in reset until at least 12 clock cycles after the
active-low RST signal is removed. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
The RST pin is 5 V tolerant.
12.5. Missing Clock Detector Reset
The Missing Clock Detector is essentially a one-shot circuit that is triggered by the MCU system clock. If
the system clock goes away for more than 100msec, the one-shot will time out and generate a reset. After
a Missing Clock Detector reset, the MCDRSF flag (RSTSRC.2) will be set, signifying the MSD as the reset
source; otherwise, this bit reads 0. The state of the RST pin is unaffected by this reset. Setting the
MSCLKE bit in the OSCICN register (see SFR Definition 13.1) enables the Missing Clock Detector.
12.6. Comparator 0 Reset
Comparator 0 can be configured as a reset input by writing a 1 to the C0RSEF flag (RSTSRC.5). Comparator 0 should be enabled using CPT0CN.7 (see SFR Definition 8.1) prior to writing to C0RSEF to prevent
any turn-on chatter on the output from generating an unwanted reset. When configured as a reset, if the
non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0–), the MCU is put
into the reset state. After a Comparator 0 Reset, the C0RSEF flag (RSTSRC.5) will read 1 signifying Comparator 0 as the reset source; otherwise, this bit reads 0. The state of the RST pin is unaffected by this
reset.
12.7. Watchdog Timer Reset
The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. The WDT will
force the MCU into the reset state when the watchdog timer overflows. To prevent the reset, the WDT
must be restarted by application software before the overflow occurs. If the system experiences a software/hardware malfunction preventing the software from restarting the WDT, the WDT will overflow and
cause a reset. This should prevent the system from running out of control.
The WDT is automatically enabled and started with the default maximum time interval on exit from all
resets. If desired, the WDT can be disabled by system software or locked 'on' to prevent accidental disabling. Once locked, the WDT cannot be disabled until the next system reset. The state of the RST pin is
unaffected by this reset.
12.7.1. Watchdog Usage
The WDT consists of a 21-bit timer running from the programmed system clock. The timer measures the
period between specific writes to its control register. If this period exceeds the programmed limit, a WDT
reset is generated. The WDT can be enabled and disabled as needed in software, or can be permanently
enabled if desired. Watchdog features are controlled via the Watchdog Timer Control Register (WDTCN)
shown in SFR Definition 12.1.
Enable/Reset WDT
The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's application software should include periodic writes of 0xA5 to WDTCN as needed to prevent a watchdog timer
overflow. The WDT is enabled and reset as a result of any system reset.
Rev. 1.7
93
C8051F2xx
Disable WDT
Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment
illustrates disabling the WDT.
CLR
MOV
MOV
SETB
EA
WDTCN,#0DEh
WDTCN,#0ADh
EA
; disable all interrupts
; disable watchdog timer
;
; re-enable interrupts
The writes of 0xDE and 0xAD must occur within 4 clock cycles of each other, or the disable operation is
ignored. Interrupts should be disabled during this procedure to avoid delay between the two writes.
Disable WDT Lockout
Writing 0xFF to WDTCN locks out the disable feature. Once locked out, the disable operation is ignored
until the next system reset. Writing 0xFF does not enable or reset the watchdog timer. Applications alays
intending to use the watchdog should write 0xFF to WDTCN in their initialization code.
Setting WDT Interval
WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equation:
43+WDTCN[2:0] x TSYSCLK , (where TSYSCLK is the system clock period).
For a 2.0 MHz system clock, this provides an interval range of 32msec to 524msec. WDTCN.7 must be
written as 0 when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] is
111b after a system reset.
SFR Definition 12.1. WDTCN: Watchdog Timer Control
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:
0xFF
xxxxx111
Bits7–0: WDT Control
Writing 0xA5 both enables and reloads the WDT.
Writing 0xDE followed within 4 clocks by 0xAD disables the WDT.
Writing 0xFF locks out the disable feature.
Bit4:
Watchdog Status Bit (when Read)
Reading the WDTCN.[4] bit indicates the Watchdog Timer Status.
0: WDT is inactive
1: WDT is active
Bits2–0: Watchdog Timeout Interval Bits
The WDTCN.[2:0] bits set the Watchdog Timeout Interval. When writing these bits,
WDTCN.7 must be set to 0.
94
Rev. 1.7
C8051F2xx
SFR Definition 12.2. RSTSRC: Reset Source
R
Bit7
R/W
R/W
R
R
C0RSEF SWRSEF WDTRSF MCDRSF
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R
Reset Value
PORSF
PINRSF
xxxxxxxx
Bit1
Bit0
SFR Address:
0xEF
(Note: Do not use read-modify-write operations on this register.)
Bit7:
Bit6:
Bit5:
Bit4:
RESERVED.
Not Used. Read only 0b.
C0RSEF: Comparator 0 Reset Enable and Flag
Write
0: Comparator 0 is not a reset source
1: Comparator 0 is a reset source (active low)
Read
Note: The value read from C0RSEF is not defined if Comparator 0 has not been enabled as
a reset source.
0: Source of prior reset was not from Comparator 0
1: Source of prior reset was from Comparator 0
SWRSF: Software Reset Force and Flag
Write
0: No Effect
1: Forces an internal reset. RST pin is not affected.
Read
Bit3:
Bit2:
Bit1:
0: Prior reset source was not from write to the SWRSF bit.
1: Prior reset source was from write to the SWRSF bit.
WDTRSF: Watchdog Timer Reset Flag (Read only)
0: Source of prior reset was not from WDT timeout.
1: Source of prior reset was from WDT timeout.
MCDRSF: Missing Clock Detector Flag (Read only)
0: Source of prior reset was not from Missing Clock Detector timeout.
1: Source of prior reset was from Missing Clock Detector timeout.
PORSF: Power-On Reset Force and Flag
Write
0: No effect
1: Forces a Power-On Reset. RST is driven low.
Read
Bit0:
0: Source of prior reset was not from POR.
1: Source of prior reset was from POR.
PINRSF: HW Pin Reset Flag
0: Source of prior reset was not from RST pin.
1: Source of prior reset was from RST pin.
Rev. 1.7
95
C8051F2xx
Table 12.1. VDD Monitor Electrical Characteristics
–40 to +85 ×C unless otherwise specified.
Parameter
Min
Typ
Max
Units
—
—
0.6
V
RST Input High Voltage
0.8 x
VDD
—
—
V
RST Input Low Voltage
—
—
0.2 x
VDD
V
RST Input Leakage Current RST = 0.0 V
—
—
50
μA
VDD for RST Output Valid
1.0
—
—
V
Reset Threshold (Vrst)
2.40
2.55
2.70
V
RST Output Low Voltage
Conditions
IOL = 8.5 mA, VDD = 2.7 to 3.6 V
Reset Time Delay
RST rising edge after crossing reset
threshold
80
100
120
ms
Missing Clock Detector
Timeout
Time from last system clock to reset
generation
100
220
500
μs
96
Rev. 1.7
C8051F2xx
13. Oscillator
The MCU includes an internal oscillator and an external oscillator drive circuit, either of which can generate
the system clock. The MCU boots from the internal oscillator after any reset. This internal oscillator can
be enabled/disabled and its frequency can be set using the Internal Oscillator Control Register (OSCICN)
as shown in SFR Definition 13.1. The internal oscillator's electrical specifications are given in Table 13.1.
Both oscillators are disabled when the RST pin is held low. The MCU can run from the internal oscillator
permanently, or it can switch to the external oscillator if desired using CLKSL bit in the OSCICN Register.
The external oscillator requires an external resonator, crystal, capacitor, or RC network connected to the
XTAL1/XTAL2 pins (see Figure 13.1). The oscillator circuit must be configured for one of these sources in
the OSCXCN register. An external CMOS clock can also provide the system clock by driving the XTAL1
pin. The XTAL1 and XTAL2 pins are NOT 5 V tolerant.
Figure 13.1. Oscillator Diagram
Rev. 1.7
97
C8051F2xx
SFR Definition 13.1. OSCICN: Internal Oscillator Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
MSCLKE
-
-
IFRDY
CLKSL
IOSCEN
IFCN1
IFCN0
00000100
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB2
Bit7:
MSCLKE: Missing Clock Enable Bit
0: Missing Clock Detector Disabled
1: Missing Clock Detector Enabled; triggers a reset if a missing clock is detected
Bits6–5: UNUSED. Read = 00b, Write = don't care
Bit4:
IFRDY: Internal Oscillator Frequency Ready Flag
0: Internal Oscillator Frequency not running at speed specified by the IFCN bits.
1: Internal Oscillator Frequency running at speed specified by the IFCN bits.
Bit3:
CLKSL: System Clock Source Select Bit
0: Uses Internal Oscillator as System Clock.
1: Uses External Oscillator as System Clock.
Bit2:
IOSCEN: Internal Oscillator Enable Bit
0: Internal Oscillator Disabled
1: Internal Oscillator Enabled
Bits1–0: IFCN1-0: Internal Oscillator Frequency Control Bits
00: Internal Oscillator typical frequency is 2 MHz.
01: Internal Oscillator typical frequency is 4 MHz.
10: Internal Oscillator typical frequency is 8 MHz.
11: Internal Oscillator typical frequency is 16 MHz.
Table 13.1. Internal Oscillator Electrical Characteristics
–40 to +85 ×C unless otherwise specified.
Parameter
Internal Oscillator Frequency
Conditions
OSCICN.[1:0] = 00
OSCICN.[1:0] = 01
OSCICN.[1:0] = 10
OSCICN.[1:0] = 11
Internal Oscillator Current Consumption OSCICN.2 = 1
Internal Oscillator Temperature Stability
Internal Oscillator Power Supply (VDD)
Stability
98
Rev. 1.7
Min
1.5
3.0
6.0
12
—
—
Typ
2.0
4.0
8.0
16
200
4
Max
2.5
5.0
10
20
—
—
Units
MHz
μA
ppm/C
—
6.4
—
%/V
C8051F2xx
SFR Definition 13.2. OSCXCN: External Oscillator Control
R
R/W
R/W
R/W
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
-
XFCN2
XFCN1
XFCN0
00110000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB1
Bit7:
XTLVLD: Crystal Oscillator Valid Flag
(Valid only when XOSCMD = 1xx.)
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: Off. XTAL1 pin is grounded internally.
010: System Clock from External CMOS Clock on XTAL1 pin.
011: System Clock from External CMOS Clock on XTAL1 pin divided by 2.
10x: RC/C Oscillator Mode with divide by 2 stage.
110: Crystal Oscillator Mode
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3:
RESERVED. Read = undefined, 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 12.5 kHz
12.5 kHz < f 30.3 kHz
30.35 kHz < f 93.8 kHz
93.8 kHz < f 26 7kHz
267 kHz < f 722 kHz
722 kHz < f 2.23 MHz
2.23 MHz < f 6.74 MHz
f > 6.74 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 = 0.44
K Factor = 1.4
K Factor = 4.4
K Factor = 13
K Factor = 38
K Factor = 100
K Factor = 420
K Factor = 1400
CRYSTAL MODE (Circuit from Figure 13.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match the crystal frequency.
RC MODE (Circuit from Figure 13.1, Option 2; XOSCMD = 10x)
Choose oscillation frequency range where:
f = 1.23(103) / (R x C), where
f = frequency of oscillation in MHz
C = capacitor value in pF
R = Pull-up resistor value in k
C MODE (Circuit from Figure 13.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x AV+), where
f = frequency of oscillation in MHz
C = capacitor value on XTAL1, XTAL2 pins in pF
VDD = Power supply voltage on MCU in volts
Rev. 1.7
99
C8051F2xx
13.1. External Crystal Example
If a crystal were used to generate the system clock for the MCU, the circuit would be as shown in
Figure 13.1, Option 1. For an ECS-110.5-20-4 crystal, the resonate frequency is 11.0592 MHz, the intrinsic capacitance is 7 pF, and the ESR is 60 W. The compensation capacitors should be 33 pF each, and
the PWB parasitic capacitance is estimated to be 2 pF. The appropriate External Oscillator Frequency
Control value (XFCN) from the Crystal column in the table in SFR Definition 13.2 (OSCXCN Register)
should be 111b.
The Crystal Oscillator Valid Flag (XTLVLD in register OSCXCN) is set to logic 1 by hardware when the
external oscillator is running and stable. The XTLVLD detection circuit requires a startup time of at least
1ms between enabling the oscillator and checking the XTLVLD flag. Switching to the external oscillator
before 1ms can result in unpredictable behavior. The recommend procedure is:
1.
2.
3.
4.
Enable the external oscillator
Wait 1 ms
Poll for XTLVLD '0' ==> '1'
Switch to the external oscillator
Switching to the external oscillator before the crystal oscillator has stabilized could result in unpredictable
behavior.
NOTE: 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, keeping the traces as short as possible and shielded with
ground plane from any other traces which could introduce noise or interference.
13.2. External RC Example
If an external RC network were used to generate the system clock for the MCU, the circuit would be as
shown in Figure 13.1, Option 2. The capacitor must be no greater than 100 pF, but using a very small
capacitor will increase the frequency drift due to the PWB parasitic capacitance. 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 kW and C = 50 pF:
f = 1.23(103)/RC = 1.23(103) / [246 x 50] = 0.1 MHz = 100 kHz
XFCN ³ log2(f/25 kHz)
XFCN ³ log2(100 kHz/25 kHz) = log2(4)
XFCN ³ 2, or code 010
13.3. External Capacitor Example
If an external capacitor were used to generate the system clock for the MCU, the circuit would be as shown
in Figure 13.1, Option 3. The capacitor must be no greater than 100 pF, but using a very small capacitor
will increase the frequency drift due to the PWB parasitic capacitance. 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)
f = KF / 150
If a frequency of roughly 90kHz is desired, select the K Factor from the table in SFR Definition 13.2 as KF
= 13:
f = 13 /150 = 0.087 MHz, or 87 kHz
Therefore, the XFCN value to use in this example is 011.
100
Rev. 1.7
C8051F2xx
14. Port Input/Output
Description
The C8051F221/231 have three I/O Ports: Port0, Port1, and Port2. The C8051F206, C8051F220/6 and
C8051F230/6 have four I/O Ports: Port0, Port1, Port2, and Port3. A wide array of digital resources can be
assigned to these ports by the simple configuration of the port's corresponding multiplexer (MUX). Please
see Figure 8.1. Additionally, all external port pins are available as analog input.
14.1. Port I/O Initialization
Port I/O initialization is straightforward. Registers PRT0MX, PRT1MX and PRT2MX must be loaded with
the appropriate values to select the digital I/O functions required by the design. The output driver characteristics of the I/O pins are defined using the Port Configuration Registers PRT0CF, PRT1CF, PRT2CF and
PRT3CF. Each Port Output driver can be configured as either Open Drain or Push-Pull. This is required
even for the digital resources selected in the PRTnMX registers, and is not automatic.
Any or all pins may be configured as digital I/O or as analog input. The default mode is digital I/O. The
P0MODE, P1MODE, P2MODE, and P3MODE special function registers are used to configure the port
pins as digital or analog as defined in this section.
The final step is initializing the individual resources selected using the appropriate setup registers. Initialization procedures for the various digital resources may be found in the detailed explanation of each available function. The reset state of each register is shown in the figures that describe each individual register.
NOTE: The input mode of pins configured for use with Timer 0, 1, or 2 must be manually configured.
1. The output mode of all ports pins must be configured regardless of whether the port pin is
either standard general-purpose I/O or controlled by a digital peripheral.
2. For all pins used as Timer inputs (P0.4/T0, P0.5/T1, P0.6/T2, and P0.7/T2EX), the output
mode must be "open-drain" (which is the reset state), and "1" must be written to the associated
port pin to prevent possible contention for the port pin that could result in an overcurrent condition. For example, to configure a Timer0, set PRT0MX's T0E Timer0 enable bit to '1' to route
Timer0 to Port Pin P0.4. Then place P0.4/T0 in open-drain configuration (which is set in
PRT0CF by default), and write a '1' to P0.4 to set its output state to high impedance for use as
a digital peripheral input (port pins also default to logic high state upon reset). Lastly, ensure
P0MODE.4 is '1' for digital input mode. (All pins default to digital input mode upon reset.)
Rev. 1.7
101
C8051F2xx
Figure 14.1. Port I/O Functional Block Diagram
Figure 14.2. Port I/O Cell Block Diagram
102
Rev. 1.7
C8051F2xx
SFR Definition 14.1. PRT0MX: Port I/O MUX Register 0
R/W
R/W
R/W
R/W
R/W
R/W
R
R/W
Reset Value
T2EXE
T2E
T1E
T0E
INT1E
INT0E
-
UARTEN
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE1
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
T2EXE: T2EX Enable Bit
0: T2EX unavailable at Port pin.
1: T2EX routed to Port Pin.
T2E: T2 Enable Bit
0: T2 unavailable at Port pin.
1: T2 routed to Port Pin.
T1E: T1 Enable Bit
0: T1 unavailable at Port pin.
1: T1 routed to Port Pin.
T0E: T0 Enable Bit
0: T0 unavailable at Port pin.
1: T0 routed to Port Pin.
INT1E: /INT1 Enable Bit
0: /INT1 unavailable at Port pin.
1: /INT1 routed to port pin.
INT0E: /INT0 Enable Bit
0: /INT0 unavailable at Port pin.
1: /INT0 routed to Port Pin.
UNUSED. Read = 0, Write = don't care.
UARTEN: UART I/O Enable
0: UART I/O unavailable at port pins.
1: TX, RX routed to pins P0.0 and P0.1, respectively.
Rev. 1.7
103
C8051F2xx
SFR Definition 14.2. PRT1MX: Port I/O MUX Register 1
R
R/W
R
R
R
R
-
SYSCKE
-
-
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
CP1OEN CP0OEN
Bit1
Bit0
Reset Value
00000000
SFR Address:
0xE2
Bit7:
Bit6:
UNUSED. Read = 0.
SYSCKE: SYSCLK Output Enable Bit
0: SYSCLK unavailable at the port pin.
1: SYSCLK output routed to pin P1.6
Bits 5–2: UNUSED. Read = 0000b, Write = don't care.
Bit1:
CP1OEN: Comparator 1 Output Enable bit.
0: CP1 unavailable at Port pin.
1: CP1 routed to Port Pin P1.5.
Bit0:
CP0OEN: Comparator 0 Output Enable Bit
0: CP0 unavailable at port pin.
1: CP0 routed to port pin P1.2.
SFR Definition 14.3. PRT2MX: Port I/O MUX Register 2
R/W
R/W
R/W
R/W
R/W
GWPUD P3WPUD P2WPUD P1WPUD P0WPUD
Bit7
Bit6
Bit5
Bit4
Bit3
Bit 7:
R/W
R/W
R/W
Reset Value
-
-
SPI0OEN
00000000
Bit2
Bit1
Bit0
SFR Address:
0xE3
GWPUD: Global Port I/O Weak Pull-up Disable Bit
0: Weak Pull-ups Enabled for all ports.
1: Weak Pull-ups Disabled (Bits 6–3 Don't cares)
Bit 6:
P3WPUD: Port 3 Weak Pull-up Disable Bit
0: Weak Pull-ups Enabled for port 3
1: Weak Pull-ups Disabled for port 3
Bit 5:
P2WPUD: Port 2 Weak Pull-up Disable Bit
0: Weak Pull-ups Enabled for port 2.
1: Weak Pull-ups Disabled for port 2
Bit 4:
P1WPUD: Port 1 Weak Pull-up Disable Bit
0: Weak Pull-ups Enabled for port 1
1: Weak Pull-ups Disabled for port 1
Bit 3:
P0WPUD: Port 0 Weak Pull-up Disable Bit
0: Weak Pull-ups Enabled for port 0
1: Weak Pull-ups Disabled for port 0
Bits 2–1: UNUSED. Read = 00b, Write = don't care.
Bit 0:
SPI0OEN: SPI Bus I/O Enable Bit.
0: SPI I/O unavailable at port pins.
1: SCK, MISO, MOSI, NSS routed to pins P2.0, P2.1, P2.2, and P2.3 respectively.
104
Rev. 1.7
C8051F2xx
14.2. General Purpose Port I/O
Each I/O port is accessed through a corresponding special function register (SFR) that is 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 PRTnMX settings (i.e., even when the pin is assigned to another signal by the MUX, the
Port Register can always still read its corresponding Port I/O pin), provided its pin is configured for digital
input mode. The exception to this is the execution of the read-modify-write instructions. The read-modifywrite instructions when operating on a port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC,
DJNZ and MOV, CLR or SETB, 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.
SFR Definition 14.4. P0: Port0 Register
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 PRT0MX, PRT1MX, and PRT2MX Registers)
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding PRT0CF.n bit = 0)
(Read - Regardless of PRT0MX, PRT1MX, and PRT2MX Register settings).
0: P0.n pin is logic low.
1: P0.n pin is logic high.
SFR Definition 14.5. PRT0CF: Port0 Configuration Register
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:
0xA4
00000000
Bits7–0: PRT0CF.[7:0]: Output Configuration Bits for P0.7–P0.0 (respectively)
0: Corresponding P0.n Output mode is Open-Drain.
1: Corresponding P0.n Output mode is Push-Pull.
Rev. 1.7
105
C8051F2xx
SFR Definition 14.6. P0MODE: Port0 Digital/Analog Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF1
Bits7–0: Port0 Digital/Analog Input Mode
0: Corresponding Port0 pin Digital Input disabled. (For analog use, i.e., ADC).
1: Corresponding Port0 pin Digital Input is enabled.
SFR Definition 14.7. P1: Port1 Register
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 PRT0MX, PRT1MX, and PRT2MX registers)
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding PRT1CF.n bit = 0)
(Read - Regardless of PRT0MX, PRT1MX, and PRT2MX Register settings).
0: P1.n pin is logic low.
1: P1.n pin is logic high.
SFR Definition 14.8. PRT1CF: Port1 Configuration Register
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
Bits7–0: PRT1CF.[7:0]: Output Configuration Bits for P1.7–P1.0 (respectively)
0: Corresponding P1.n Output Mode is Open-Drain.
1: Corresponding P1.n Output Mode is Push-Pull.
106
Rev. 1.7
Bit0
SFR Address:
0xA5
C8051F2xx
SFR Definition 14.9. P1MODE: Port1 Digital/Analog Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF2
Bits7–0: Port1 Digital/Analog Output Mode
0: Corresponding Port1 pin Digital Input disabled. (For analog use, i.e., ADC or
comparators).
1: Corresponding Port1 pin Digital Input is enabled.
SFR Definition 14.10. P2: Port2 Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
11111111
Bit7
Bit6
Bit
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0xA0
Bits7–0: P2.[7:0]
(Write - Output appears on I/O pins per PRT0MX, PRT1MX, and PRT2MX registers)
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding PRT2CF.n bit = 0)
(Read - Regardless of PRT0MX, PRT1MX, and PRT2MX Register settings).
0: P2.n is logic low.
1: P2.n is logic high.
SFR Definition 14.11. PRT2CF: Port2 Configuration Register
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:
0xA6
Bits7–0: PRT2CF.[7:0]: Output Configuration Bits for P2.7–P2.0 (respectively)
0: Corresponding P2.n Output Mode is Open-Drain.
1: Corresponding P2.n Output Mode is Push-Pull.
Rev. 1.7
107
C8051F2xx
SFR Definition 14.12. P2MODE: Port2 Digital/Analog Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF3
Bits7–0: Port2 Digital/Analog Output Mode
0: Corresponding Port2 pin Digital Input disabled. (For analog use, i.e., ADC).
1: Corresponding Port2 pin Digital Input is enabled.
SFR Definition 14.13. P3: Port3 Register*
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
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)
0xB0
Bits7–0: P3.[7:0]
(Write)
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding PRT3CF.n bit = 0)
(Read)
0: P3.n is logic low.
1: P3.n is logic high.
SFR Definition 14.14. PRT3CF: Port3 Configuration Register*
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
Bits7–0: PRT3CF.[7:0]: Output Configuration Bits for P3.7–P3.0 (respectively)
0: Corresponding P3.n Output Mode is Open-Drain.
1: Corresponding P3.n Output Mode is Push-Pull.
108
Rev. 1.7
Bit0
SFR Address:
0xA7
C8051F2xx
SFR Definition 14.15. P3MODE: Port3 Digital/Analog Input Mode*
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF4
Bits7–0: Port3 Digital/Analog Output Mode
0: Corresponding Port3 pin Digital Input disabled. (For analog use, i.e., ADC).
1: Corresponding Port3 pin Digital Input is enabled.
* (Available on C8051F206, C8051F220/6 and C8051F230/6)
Table 14.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 C unless otherwise specified.
Parameter
Conditions
IOH = –10 uA, Port I/O push-pull
Output High Voltage
IOH = –3 mA, Port I/O push-pull
IOH = –10 mA, Port I/O push-pull
Output Low Voltage
Min
VDD –
0.1
VDD –
0.7
IOL = 10 uA
IOL = 8.5 mA
IOL = 25 mA
Typ
VDD –
0.8
0.1
0.6
0.7 x
VDD
0.3 x
VDD
Capacitive Loading
30
3
Rev. 1.7
V
V
Input Low Voltage
DGND < Port Pin < VDD, Pin Tri-state
Weak Pull-up Off
Weak Pull-up On
Units
V
1.0
Input High Voltage
Input Leakage Current
Max
1
V
A
pF
109
C8051F2xx
15. Serial Peripheral Interface Bus
The Serial Peripheral Interface (SPI) provides access to a four-wire, full-duplex, serial bus. SPI supports
the connection of multiple slave devices to a master device on the same bus. A separate slave-select signal (NSS) is used to select a slave device and enable a data transfer between the master and the selected
slave. Multiple masters on the same bus are also supported. Collision detection is provided when two or
more masters attempt a data transfer at the same time. The SPI can operate as either a master or a slave.
When the SPI is configured as a master, the maximum data transfer rate (bits/sec) is one-half the system
clock frequency.
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, and the serial input data
synchronously with the system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less that 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 ¼ the system clock frequency. This is provided that the master issues SCK, NSS, and the
serial input data synchronously with the system clock.
Figure 15.1. SPI Block Diagram
110
Rev. 1.7
C8051F2xx
Figure 15.2. SPI Block Diagram
15.1. Signal Descriptions
The four signals used by the SPI (MOSI, MISO, SCK, NSS) are described below.
15.1.1. Master Out, Slave In
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. Data is transferred most-significant bit first.
15.1.2. Master In, Slave Out
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. Data is transferred most-significant bit first.
A SPI slave places the MISO pin in a high-impedance state when the slave is not selected.
15.1.3. Serial Clock
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.
15.1.4. Slave Select
The slave select (NSS) signal is an input used to select the SPI module when in slave mode by a master,
or to disable the SPI module when in master mode. When in slave mode, it is pulled low to initiate a data
transfer and remains low for the duration of the transfer.
Rev. 1.7
111
C8051F2xx
15.2. Operation
Only a SPI master device can initiate a data transfer. The SPI is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.1). Writing a byte of data to the SPI data register (SPI0DAT) when in
Master Mode starts a data transfer. The SPI 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. The SPI
master can be configured to shift in/out from one to eight bits in a transfer operation in order to accommodate slave devices with different word lengths. The SPIFRS bits in the SPI Configuration Register
(SPI0CFG.[2:0]) are used to select the number of bits to shift in/out in a transfer operation.
While the SPI 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. The data byte received from the slave replaces the data in the master's data register. Therefore, the
SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data transfer in both directions is synchronized with the serial clock generated by the master. Figure 15.3 illustrates the full-duplex
operation of an SPI master and an addressed slave.
Figure 15.3. Full Duplex Operation
The SPI data register is double buffered on reads, but not on a write. If a write to SPI0DAT is attempted
during a data transfer, the WCOL flag (SPI0CN.6) will be set to logic 1 and the write is ignored. The current data transfer will continue uninterrupted. A read of the SPI data register by the system controller actually reads the receive buffer. If the receive buffer still holds unread data from a previous transfer when the
last bit of the current transfer is shifted into the SPI shift register, a receive overrun occurs and the
RXOVRN flag (SPI0CN.4) is set to logic 1. The new data is not transferred to the receive buffer, allowing
the previously received data byte to be read. The data byte causing the overrun is lost.
When the SPI is enabled and not configured as a master, it will operate as an SPI slave. Another SPI
device acting as a master will initiate a transfer by driving the NSS signal low. The master then shifts data
out of the shift register on the MOSI pin using the its serial clock. The SPIF flag is set to logic 1 at the end
of a data transfer (when the NSS signal goes high). The slave can load its shift register for the next data
transfer by writing to the SPI data register. The slave must make the write to the data register at least one
SPI serial clock cycle before the master starts the next transmission. Otherwise, the byte of data already in
the slave's shift register will be transferred.
112
Rev. 1.7
C8051F2xx
Multiple masters may reside on the same bus. A Mode Fault flag (MODF, SPI0CN.5) is set to logic 1 when
the SPI is configured as a master (MSTEN = 1) and its slave select signal NSS is pulled low. When the
Mode Fault flag is set, the MSTEN and SPIEN bits of the SPI control register are cleared by hardware,
thereby placing the SPI module in an "off-line" state. In a multiple-master environment, the system controller should check the state of the SLVSEL flag (SPI0CN.2) to ensure the bus is free before setting the
MSTEN bit and initiating a data transfer.
15.2. Serial Clock Timing
As shown in Figure 15.4, four combinations of serial clock phase and polarity can be selected using the
clock control bits in the SPI Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.7) selects one
of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.6) selects between an activehigh or active-low clock. Both master and slave devices must be configured to use the same clock phase
and polarity. Note: the SPI should be disabled (by clearing the SPIEN bit, SPI0CN.0) while changing the
clock phase and polarity.
The SPI Clock Rate Register (SPI0CKR) as shown in SFR Definition 15.3 controls the master mode serial
clock frequency. This register is ignored when operating in slave mode.
Figure 15.4. Full Duplex Operation
15.3. SPI Special Function Registers
The SPI 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 SPI Bus are described in
the following section.
Rev. 1.7
113
C8051F2xx
SFR Definition 15.1. SPI0CFG: SPI Configuration
R/W
R/W
R
R
R
CKPHA
CKPOL
BC2
BC1
BC0
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
SPIFRS2 SPIFRS1 SPIFRS0
Bit7:
CKPHA: SPI Clock Phase.
This bit controls the SPI clock phase.
0: Data sampled on first edge of SCK period.
1: Data sampled on second edge of SCK period.
Bit6:
CKPOL: SPI Clock Polarity.
This bit controls the SPI clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Bit2
Bit1
Bit0
Reset Value
00000111
SFR Address:
0x9A
Bits5–3: BC2–BC0: SPI Bit Count.
Indicates which of the up to 8 bits of the SPI word have been transmitted.
0
0
0
0
1
1
1
1
Bits2–0:
0
1
0
1
0
1
0
1
Bit Transmitted
Bit 0 (LSB)
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7 (MSB)
SPIFRS2–SPIFRS0: SPI Frame Size.
These three bits determine the number of bits to shift in/out of the SPI shift register during a
data transfer in master mode. They are ignored in slave mode.
0
0
0
0
1
1
1
1
114
BC2–BC0
0
0
1
1
0
0
1
1
SPIFRS
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Bits Shifted
1
2
3
4
5
6
7
8
Rev. 1.7
C8051F2xx
SFR Definition 15.2. SPI0CN: SPI Control
R/W
R/W
R/W
R/W
R
R
R/W
R/W
Reset Value
SPIF
WCOL
MODF
RXOVRN
TXBSY
SLVSEL
MSTEN
SPIEN
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF8
Bit7:
SPIF: SPI 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.
Bit6:
WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware (and generates a SPI interrupt) to indicate a write to the
SPI data register was attempted while a data transfer was in progress. It is cleared by software.
Bit5:
MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI interrupt) when a master mode
collision is detected (NSS is low and MSTEN = 1). This bit is not automatically cleared by
hardware. It must be cleared by software.
Bit4:
RXOVRN: Receive Overrun Flag.
This bit is set to logic 1 by hardware (and generates a SPI 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 SPI shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bit3:
TXBSY: Transmit Busy Flag.
This bit is set to logic 1 by hardware while a master mode transfer is in progress. It is
cleared by hardware at the end of the transfer.
Bit2:
SLVSEL: Slave Selected Flag.
This bit is set to logic 1 whenever the NSS pin is low indicating it is enabled as a slave. It is
cleared to logic 0 when NSS is high (slave disabled).
Bit1:
MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
Bit0:
SPIEN: SPI Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
Rev. 1.7
115
C8051F2xx
SFR Definition 15.3. SPI0CKR: SPI Clock Rate Register
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:
0x9D
Bits7–0: SCR7–SCR0: SPI Clock Rate
These bits determine the frequency of the SCK output when the SPI module is configured for master
mode operation. The SCK clock frequency is a divided down version of the system clock,
and is given in the following equations:
fSCK = 0.5 x fSYSCLK / (SPI0CKR + 1), for 0 < SPI0CKR < 255,
SFR Definition 15.4. SPI0DAT: SPI Data Register
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:
0x9B
Bits7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI data. Writing data to SPI0DAT
places the data immediately into the shift register and initiates a transfer when in Master
Mode. A read of SPI0DAT returns the contents of the receive buffer.
116
Rev. 1.7
C8051F2xx
16. UART
Description
The CIP-51 includes a serial port (UART) capable of asynchronous transmission. The UART can function
in full duplex mode. In all modes, receive data is buffered in a holding register. This allows the UART to
start reception of a second incoming data byte before software has finished reading the previous data byte.
The UART has an associated Serial Control Register (SCON) and a Serial Data Buffer (SBUF) in the
SFRs. The single SBUF location provides access to both transmit and receive registers. Reads access
the Receive register and writes access the Transmit register automatically.
The UART is capable of generating interrupts if enabled. The UART has two sources of interrupts: a
Transmit Interrupt flag, TI (SCON.1) set when transmission of a data byte is complete, and a Receive Interrupt flag, RI (SCON.0) set when reception of a data byte is complete. The UART interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software. This allows software to determine the cause of the UART interrupt (transmit complete or
receive complete).
Figure 16.1. UART Block Diagram
Rev. 1.7
117
C8051F2xx
16.1. UART Operational Modes
The UART provides four operating modes (one synchronous and three asynchronous) selected by setting
configuration bits in the SCON register. These four modes offer different baud rates and communication
protocols. The four modes are summarized in Table 16.1 below. Detailed descriptions follow.
Table 16.1. UART Modes
Mode
0
1
2
3
Synchronization
Synchronous
Asynchronous
Asynchronous
Asynchronous
Baud Clock
SYSCLK/12
Timer 1 or Timer 2 Overflow
SYSCLK/32 or SYSCLK/64
Timer 1 or Timer 2 Overflow
Data Bits
8
8
9
9
Start/Stop Bits
None
1 Start, 1 Stop
1 Start, 1 Stop
1 Start, 1 Stop
16.1.1. Mode 0: Synchronous Mode
Mode 0 provides synchronous, half-duplex communication. Serial data is transmitted and received on the
RX pin. The TX pin provides the shift clock for both transmit and receive. The MCU must be the master
since it generates the shift clock for transmission in both directions (see the interconnect diagram in
Figure 16.2).
Eight data bits are transmitted/received, LSB first (see the timing diagram in Figure 16.3). Data transmission begins when an instruction writes a data byte to the SBUF register. The TI Transmit Interrupt Flag
(SCON.1) is set at the end of the eighth bit time. Data reception begins when the REN Receive Enable bit
(SCON.4) is set to logic 1 and the RI Receive Interrupt Flag (SCON.0) is cleared. One cycle after the
eighth bit is shifted in, the RI flag is set and reception stops until software clears the RI bit. An interrupt will
occur if enabled when either TI or RI are set.
The Mode 0 baud rate is system clock frequency divided by twelve.
Figure 16.2. UART Mode 0 Interconnect
Figure 16.3. UART Mode 0 Timing Diagram
118
Rev. 1.7
C8051F2xx
16.1.2. Mode 1: 8-Bit UART, Variable Baud Rate
Mode 1 provides standard asynchronous, full duplex communication using a total of 10 bits per data byte:
one start bit, eight data bits (LSB first), and one stop bit (see the timing diagram in Figure 16.4). Data are
transmitted from the TX pin and received at the RX pin (see the interconnection diagram in Figure 16.5).
On receive, the eight data bits are stored in SBUF and the stop bit goes into RB8 (SCON.2).
Data transmission begins when an instruction writes a data byte to the SBUF register. The TI Transmit
Interrupt Flag (SCON.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN Receive Enable bit (SCON.4) is set to logic 1. After the stop bit
is received, the data byte will be loaded into the SBUF receive register if the following conditions are met:
RI must be logic 0, and if SM2 is logic 1, the stop bit must be logic 1.
If these conditions are met, the eight bits of data are stored in SBUF, the stop bit is stored in RB8, and the
RI flag is set. If these conditions are not met, SBUF and RB8 will not be loaded and the RI flag will not be
set. An interrupt will occur if enabled when either TI or RI is set.
Figure 16.4. UART Mode 1 Timing Diagram
The baud rate generated in Mode 1 is a function of timer overflow. The UART can use Timer 1 operating in
8-bit Counter/Timer with Auto-Reload Mode, or Timer 2 operating in Baud Rate Generator Mode to generate the baud rate (note that the TX and RX clock sources are selected separately). On each timer overflow
event (a rollover from all ones (0xFF for Timer 1, 0xFFFF for Timer 2) to zero), a clock is sent to the baud
rate logic.
When Timer 1 is selected as a baud rate source, the SMOD bit (PCON.7) selects whether or not to divide
the Timer 1 overflow rate by two. On reset, the SMOD bit is logic 0, thus selecting the lower speed baud
rate by default. The SMOD bit affects the baud rate generated by Timer 1 as follows:
Mode 1 Baud Rate = (1 / 32) x T1_OVERFLOWRATE (when the SMOD bit is set to logic 0).
Mode 1 Baud Rate = (1 / 16) x T1_OVERFLOWRATE (when the SMOD bit is set to logic 1).
When Timer 2 is selected as a baud rate source, the baud rate generated by Timer 2 is as follows:
Mode 1 Baud Rate = (1 / 16) x T2_OVERFLOWRATE.
The Timer 1 overflow rate is determined by the Timer 1 clock source (T1CLK) and reload value (TH1). The
frequency of T1CLK can be selected as SYSCLK, SYSCLK/12, or an external clock source. The Timer 1
overflow rate can be calculated as follows:
T1_OVERFLOWRATE = T1CLK / (256 – TH1).
For example, assume TMOD = 0x20.
Rev. 1.7
119
C8051F2xx
If T1M (CKCON.4) is logic 1, then the above equation becomes:
T1_OVERFLOWRATE = (SYSCLK) / (256 – TH1).
If T1M (CKCON.4) is logic 0, then the above equation becomes:
T1_OVERFLOWRATE = (SYSCLK/12) / (256 – TH1).
The Timer 2 overflow rate, when in Baud Rate Generator Mode and using an internal clock source, is
determined solely by the Timer 2 16-bit reload value (RCAP2H:RCAP2L). The Timer 2 clock source is
fixed at SYSCLK/2. The Timer 2 overflow rate can be calculated as follows:
T2_OVERFLOWRATE = (SYSCLK/2) / (65536 – [RCAP2H:RCAP2L]).
Timer 2 can be selected as the baud rate generator for RX and/or TX by setting RCLK (T2CON.5) and/or
TCLK (T2CON.4), respectively. When either RCLK or TCLK is set to logic 1, Timer 2 interrupts are automatically disabled and the timer is forced into Baud Rate Generator Mode with SYSCLK/2 as its clock
source. If a different timebase is required, setting the C/T2 bit (T2CON.1) to logic 1 will allow Timer 2 to be
clocked from the external input pin T2. See the Timers section for complete timer configuration details.
Figure 16.5. UART Modes 1, 2, and 3 Interconnect Diagram
120
Rev. 1.7
C8051F2xx
16.1.3. Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 2 provides asynchronous, full-duplex communication using 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 (see timing diagram in
Figure 16.6). On transmit, the ninth data bit is determined by the value in TB8 (SCON.3). It can be
assigned the value of the parity flag P in the PSW or used in multiprocessor communications. On receive,
the ninth data bit goes into RB8 (SCON.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF register. The TI Transmit
Interrupt Flag (SCON.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN Receive Enable bit (SCON.4) is set to logic 1. After the stop bit
is received, the data byte will be loaded into the SBUF receive register if the following conditions are met:
RI must be logic 0, and if SM2 is logic 1, the 9th bit must be logic 1.
If these conditions are met, the eight bits of data is stored in SBUF, the ninth bit is stored in RB8 and the RI
flag is set. If these conditions are not met, SBUF and RB8 will not be loaded and the RI flag will not be set.
An interrupt will occur if enabled when either TI or RI are set.
The baud rate in Mode 2 is a direct function of the system clock frequency as follows:
Mode 2 Baud Rate = 2SMOD x (SYSCLK / 64).
The SMOD bit (PCON.7) selects whether to divide SYSCLK by 32 or 64. In the formula, 2 is raised to the
power SMOD, resulting in a baud rate of either 1/32 or 1/64 of the system clock frequency. On reset, the
SMOD bit is logic 0, thus selecting the lower speed baud rate by default.
Figure 16.6. UART Modes 2 and 3 Timing Diagram
16.1.4. Mode 3: 9-Bit UART, Variable Baud Rate
Mode 3 is the same as Mode 2 in all respects except the baud rate is variable. The baud rate is determined in the same manner as for Mode 1. Mode 3 operation transmits 11 bits: a start bit, 8 data bits (LSB
first), a programmable ninth data bit, and a stop bit. Timer 1 or Timer 2 overflows generate the baud rate
just as with Mode 1. In summary, Mode 3 transmits using the same protocol as Mode 2 but with Mode 1
baud rate generation.
Rev. 1.7
121
C8051F2xx
16.2. Multiprocessor Communications
Modes 2 and 3 support 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 SM2 bit (SCON.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 one (RB8 = 1) signifying an
address byte has been received. In the UART's 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 SM2 bit
to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave
their SM2 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 SM2 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).
Figure 16.7. UART Multi-Processor Mode Interconnect Diagram
Table 16.2. Oscillator Frequencies for Standard Baud Rates
Oscillator Frequency
(MHz)
24.0
23.592
22.1184
18.432
16.5888
14.7456
12.9024
11.0592
9.216
122
Divide Factor
Timer 1 Load Value*
Resulting Baud Rate**
208
205
192
160
144
128
112
96
80
0xF3
0xF3
0xF4
0xF6
0xF7
0xF8
0xF9
0xFA
0xFB
115200 (115384)
115200 (113423)
115200
115200
115200
115200
115200
115200
115200
Rev. 1.7
C8051F2xx
Table 16.2. Oscillator Frequencies for Standard Baud Rates (Continued)
Oscillator Frequency
(MHz)
7.3728
5.5296
3.6864
1.8432
24.576
25.0
25.0
24.576
24.0
23.592
22.1184
18.432
16.5888
14.7456
12.9024
11.0592
9.216
7.3728
5.5296
3.6864
1.8432
Divide Factor
Timer 1 Load Value*
Resulting Baud Rate**
64
48
32
16
320
434
868
848
833
819
768
640
576
512
448
348
320
256
192
128
64
0xFC
0xFD
0xFE
0xFF
0xEC
0xE5
0xCA
0xCB
0xCC
0xCD
0xD0
0xD8
0xDC
0xE0
0xE4
0xE8
0xEC
0xF0
0xF4
0xF8
0xFC
115200
115200
115200
115200
76800
57600 (57870)
28800
28800 (28921)
28800 (28846)
28800 (28911)
28800
28800
28800
28800
28800
28800
28800
28800
28800
28800
28800
SFR Definition 16.1. SBUF: Serial (UART) Data Buffer
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:
0x99
00000000
Bits7–0: SBUF.[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)
This is actually two registers; a transmit and a receive buffer register. When data is moved
to SBUF, it goes to the transmit buffer and is held for serial transmission. Moving a byte to
SBUF is what initiates the transmission. When data is moved from SBUF, it comes from the
receive buffer.
Rev. 1.7
123
C8051F2xx
SFR Definition 16.2. SCON: Serial Port Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SM0
SM1
SM2
REN
TB8
RB8
TI
RI
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0x98
Bits7–6: SM0–SM1: Serial Port Operation Mode.
These bits select the Serial Port Operation Mode.
SM0
0
0
1
1
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
124
SM1
0
1
0
1
Mode
Mode 0: Synchronous Mode
Mode 1: 8-Bit UART, Variable Baud Rate
Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 3: 9-Bit UART, Variable Baud Rate
SM2: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port Operation Mode.
Mode 0: No effect
Mode 1: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI will only be activated if stop bit is logic level 1.
Mode 2 and 3: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI is set and an interrupt is generated only when the ninth bit is logic 1.
REN: Receive Enable.
This bit enables/disables the UART receiver.
0: UART reception disabled.
1: UART reception enabled.
TB8: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in Modes 2 and 3. It is
not used in Modes 0 and 1. Set or cleared by software as required.
RB8: Ninth Receive Bit.
The bit is assigned the logic level of the ninth bit received in Modes 2 and 3. In Mode 1, if
SM2 is logic 0, RB8 is assigned the logic level of the received stop bit. RB8 is not used in
Mode 0.
TI: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by the UART (after the 8th bit in
Mode 0, or at the beginning of the stop bit in other modes). When the UART interrupt is
enabled, setting this bit causes the CPU to vector to the UART interrupt service routine.
This bit must be cleared manually by software
RI: Receive Interrupt Flag.
Set by hardware when a byte of data has been received by the UART (after the 8th bit in
Mode 0, or after the stop bit in other modes – see SM2 bit for exception). When the UART
interrupt is enabled, setting this bit causes the CPU to vector to the UART interrupt service
routine. This bit must be cleared manually by software.
Rev. 1.7
C8051F2xx
17. Timers
The CIP-51 implements three, 16-bit counter/timers comparable with those found in the standard 8051
MCU's. These can be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0 and Timer 1 are nearly identical and have four primary modes of operation. Timer
2 offers additional capabilities not available in Timers 0 and 1, such as capture and baud rate generation.
Timer 0 and Timer 1:
13-bit counter/timer
16-bit counter/timer
8-bit counter/timer with auto-reload
Two 8-bit counter/timers (Timer 0 only)
Timer 2:
16-bit counter/timer with auto-reload
16-bit counter/timer with capture
Baud rate generator
When functioning as a timer, the counter/timer registers are incremented on each clock tick. Clock ticks
are derived from the system clock divided by either one or twelve as specified by the Timer Clock Select
bits (T2M–T0M) in CKCON. The twelve-clocks-per-tick option provides compatibility with the older generation of the 8051 family. Applications that require a faster timer can use the one-clock-per-tick option.
When functioning as a counter, a counter/timer register is incremented on each high-to-low transition at the
selected input pin (P0.4/T0, P0.5/T1, or P0.6/T2. Events with a frequency of up to one-fourth the system
clock's frequency can be counted. The input signal need not be periodic, but it should be held at a given
level for at least two full system clock cycles to ensure the level is sampled.
17.1. Timer 0 and Timer 1
Timer 0 and Timer 1 are accessed and controlled through SFR's. Each counter/timer is implemented as a
16-bit register accessed as two separate bytes: a low byte (TL0 or TL1) and a high byte (TH0 or TH1). The
Counter/Timer Control (TCON) register is used to enable Timer 0 and Timer 1 as well as indicate their status. Both counter/timers operate in one of four primary modes selected by setting the Mode Select bits
M1–M0 in the Counter/Timer Mode (TMOD) register. Each timer can be configured independently. Following is a detailed description of each operating mode.
17.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as a 13-bit counter/timer in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically and Timer 1 is configured in the same
manner as described for Timer 0.
The TH0 register holds the eight MSB's of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4–TL0.0. The three upper bits of TL0 (TL0.7–TL0.5) are indeterminate and should be masked out or
ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to
0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if enabled.
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. Clearing C/T selects the system clock as
the input for the timer. When C/T0 is set to logic 1, high-to-low transitions at the selected input pin increment the timer register. (Refer to section 14 for information on selecting and configuring external I/O pins.)
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is 0 or the input signal /INT0
is logic-level one. Setting GATE0 to logic 1 allows the timer to be controlled by the external input signal
/INT0, facilitating pulse width measurements.
Rev. 1.7
125
C8051F2xx
TR0
GATE0
0
X
1
0
1
1
1
1
X = Don’t Care
/INT0
X
X
0
1
Counter/Timer
Disabled
Enabled
Disabled
Enabled
Setting TR0 does not reset the timer register. The timer register should be initialized to the desired value
before enabling the timer.
TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0.
Figure 17.1. T0 Mode 0 Block Diagram
17.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The
counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
126
Rev. 1.7
C8051F2xx
17.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. The TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from
all ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0.
If enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not changed. TL0
must be initialized to the desired value before enabling the timer for the first count to be correct. When in
Mode 2, Timer 1 operates identically to Timer 0. Both counter/timers are enabled and configured in Mode
2 in the same manner as Mode 0.
Figure 17.2. T0 Mode 2 Block Diagram
Rev. 1.7
127
C8051F2xx
17.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
Timer 0 and Timer 1 behave differently in Mode 3. Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/timer in TL0 is controlled using the Timer 0 control/status bits in
TCON and TMOD: TR0, C/T0, GATE0 and TF0. It can use either the system clock or an external input signal as its time base. The TH0 register is restricted to a timer function sourced by the system clock. TH0 is
enabled using the Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and
thus controls the Timer 1 interrupt.
Timer 1 is inactive in Mode 3, so with Timer 0 in Mode 3, Timer 1 can be turned off and on by switching it
into and out of its Mode 3. When Timer 0 is in Mode 3, Timer 1 can be operated in Modes 0, 1 or 2, but
cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However, the Timer
1 overflow can be used for baud rate generation. Refer to Section 16 (UART) for information on configuring Timer 1 for baud rate generation.
Figure 17.3. T0 Mode 3 Block Diagram
128
Rev. 1.7
C8051F2xx
SFR Definition 17.1. TCON: Timer Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x88
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow detected.
1: Timer 1 has overflowed.
TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow detected.
1: Timer 0 has overflowed.
TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
IE1: External Interrupt 1.
This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine if IT1 = 1. This flag is the inverse of the /INT1 input signal's logic level
when IT1 = 0.
IT1: Interrupt 1 Type Select.
This bit selects whether the configured /INT1 signal will detect falling edge or active-low
level-sensitive interrupts.
0: /INT1 is level triggered.
1: /INT1 is edge triggered.
IE0: External Interrupt 0.
This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine if IT0 = 1. This flag is the inverse of the /INT0 input signal's logic level
when IT0 = 0.
IT0: Interrupt 0 Type Select.
This bit selects whether the configured /INT0 signal will detect falling edge or active-low
level-sensitive interrupts.
0: /INT0 is level triggered.
1: /INT0 is edge triggered.
Rev. 1.7
129
C8051F2xx
SFR Definition 17.2. TMOD: Timer Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GATE1
C/T1
T1M1
T1M0
GATE0
C/T0
T0M1
T0M0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x89
Bit7:
GATE1: Timer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND /INT1 = logic level one.
Bit6:
C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
P0.5/T1.
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
T1M1
0
0
1
1
Bit3:
T1M0
0
1
0
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Timer 1 Inactive/stopped
GATE0: Timer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND /INT0 = logic level one.
Bit2:
C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
P0.4/T0.
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
T0M1
0
0
1
1
130
T0M0
0
1
0
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Two 8-bit counter/timers
Rev. 1.7
C8051F2xx
SFR Definition 17.3. CKCON: Clock Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
T2M
T1M
T0M
-
-
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8E
Bits7–6: UNUSED. Read = 00b, Write = don't care.
Bit5:
T2M: Timer 2 Clock Select.
This bit controls the division of the system clock supplied to Timer 2. This bit is ignored
when the timer is in baud rate generator mode or counter mode (i.e. C/T2 = 1).
0: Timer 2 uses the system clock divided by 12.
1: Timer 2 uses the system clock.
Bit4:
T1M: Timer 1 Clock Select.
This bit controls the division of the system clock supplied to Timer 1.
0: Timer 1 uses the system clock divided by 12.
1: Timer 1 uses the system clock.
Bit3:
T0M: Timer 0 Clock Select.
This bit controls the division of the system clock supplied to Counter/Timer 0.
0: Counter/Timer uses the system clock divided by 12.
1: Counter/Timer uses the system clock.
Bits2–0: UNUSED. Read = 000b, Write = don't care.
Rev. 1.7
131
C8051F2xx
SFR Definition 17.4. TL0: Timer 0 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:
0x8A
R/W
Reset Value
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
SFR Definition 17.5. TL1: Timer 1 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8B
R/W
Reset Value
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
SFR Definition 17.6. TH0: Timer 0 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8C
R/W
Reset Value
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 17.7. TH1: Timer 1 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
132
Rev. 1.7
Bit1
Bit0
SFR Address:
0x8D
C8051F2xx
17.2. Timer 2
Timer 2 is a 16-bit counter/timer formed by the two 8-bit SFR's: TL2 (low byte) and TH2 (high byte). As
with Timers 0 and 1, Timer 2 can use either the system clock or transitions on an external input pin as its
clock source. The Counter/Timer Select bit C/T2 bit (T2CON.1) selects the clock source for Timer 2.
Clearing C/T2 selects the system clock as the input for the timer (divided by either one or twelve as specified by the Timer Clock Select bit T2M in CKCON). When C/T2 is set to 1, high-to-low transitions at the T2
input pin increment the counter/timer register. (Refer to Section 14 for information on selecting and configuring external I/O pins.) Timer 2 can also be used to start an ADC Data Conversion (see section 5).
Timer 2 offers capabilities not found in Timer 0 and Timer 1. It operates in one of three modes: 16-bit
Counter/Timer with Capture, 16-bit Counter/Timer with Auto-Reload or Baud Rate Generator Mode. Timer
2's operating mode is selected by setting configuration bits in the Timer 2 Control (T2CON) register. Below
is a summary of the Timer 2 operating modes and the T2CON bits used to configure the counter/timer.
Detailed descriptions of each mode follow.
RCLK
0
0
0
1
1
X
TCLK
0
0
1
0
1
X
CP/RL2
1
0
X
X
X
X
TR2
1
1
1
1
1
0
Mode
16-bit Counter/Timer with Capture
16-bit Counter/Timer with Auto-Reload
Baud Rate Generator for TX
Baud Rate Generator for RX
Baud Rate Generator for TX and RX
Off
Rev. 1.7
133
C8051F2xx
17.2.1. Mode 0: 16-bit Counter/Timer with Capture
In this mode, Timer 2 operates as a 16-bit counter/timer with capture facility. A high-to-low transition on the
T2EX input pin causes the 16-bit value in Timer 2 (TH2, TL2) to be loaded into the capture registers
(RCAP2H, RCAP2L).
Timer 2 can use either SYSCLK, SYSCLK divided by 12, or high-to-low transitions on the external T2 input
pin as its clock source when operating in Counter/Timer with Capture mode. Clearing the C/T2 bit
(T2CON.1) selects the system clock as the input for the timer (divided by one or twelve as specified by the
Timer Clock Select bit T2M in CKCON). When C/T2 is set to logic 1, a high-to-low transition at the T2 input
pin increments the counter/timer register. As the 16-bit counter/timer register increments and overflows
from 0xFFFF to 0x0000, the TF2 timer overflow flag (T2CON.7) is set and an interrupt will occur if the interrupt is enabled.
Counter/Timer with Capture mode is selected by setting the Capture/Reload Select bit CP/RL2 (T2CON.0)
and the Timer 2 Run Control bit TR2 (T2CON.2) to logic 1. The Timer 2 External Enable EXEN2
(T2CON.3) must also be set to logic 1 to enable a capture. If EXEN2 is cleared, transitions on T2EX will
be ignored.
Figure 17.4. T2 Mode 0 Block Diagram
134
Rev. 1.7
C8051F2xx
17.2.2. Mode 1: 16-bit Counter/Timer with Auto-Reload
The Counter/Timer with Auto-Reload mode sets the TF2 timer overflow flag when the counter/timer register overflows from 0xFFFF to 0x0000. An interrupt is generated if enabled. On overflow, the 16-bit value
held in the two capture registers (RCAP2H, RCAP2L) is automatically loaded into the counter/timer register and the timer is restarted.
Counter/Timer with Auto-Reload mode is selected by clearing the CP/RL2 bit. Setting TR2 to logic 1
enables and starts the timer. Timer 2 can use either the system clock or transitions on an external input pin
as its clock source, as specified by the C/T2 bit. If EXEN2 is set to logic 1, a high-to-low transition on T2EX
will also cause Timer 2 to be reloaded. If EXEN2 is cleared, transitions on T2EX will be ignored.
Figure 17.5. T2 Mode 1 Block Diagram
Rev. 1.7
135
C8051F2xx
17.2.3. Mode 2: Baud Rate Generator
Timer 2 can be used as a baud rate generator for the serial port (UART) when the UART is operated in
modes 1 or 3 (refer to Section 16.1 for more information on UART operational modes). In Baud Rate Generator mode, Timer 2 works similarly to the auto-reload mode. On overflow, the 16-bit value held in the two
capture registers (RCAP2H, RCAP2L) is automatically loaded into the counter/timer register. However, the
TF2 overflow flag is not set and no interrupt is generated. Instead, the overflow event is used as the input
to the UART's shift clock. Timer 2 overflows can be used to generate baud rates for transmit and/or
receive independently.
The Baud Rate Generator mode is selected by setting RCLK (T2CON.5) and/or TCLK (T2CON.4) to logic
one. When RCLK or TCLK is set to logic 1, Timer 2 operates in the auto-reload mode regardless of the
state of the CP/RL2 bit. The baud rate for the UART, when operating in mode 1 or 3, is determined by the
Timer 2 overflow rate:
Baud Rate = Timer 2 Overflow Rate / 16.
Note, in all other modes, the time base for the timer is the system clock divided by one or twelve as
selected by the T2M bit in CKCON. However, in Baud Rate Generator mode, the time base is the system
clock divided by two. No other divisor selection is possible. If a different time base is required, setting the
C/T2 bit to logic 1 will allow the time base to be derived from the external input pin T2. In this case, the
baud rate for the UART is calculated as:
Baud Rate = FCLK / [32 x (65536 – [RCAP2H:RCAP2L]) ]
Where FCLK is the frequency of the signal supplied to T2 and [RCAP2H:RCAP2L] is the 16-bit value held
in the capture registers.
As explained above, in Baud Rate Generator mode, Timer 2 does not set the TF2 overflow flag and therefore cannot generate an interrupt. However, if EXEN2 is set to logic 1, a high-to-low transition on the T2EX
input pin will set the EXF2 flag and a Timer 2 interrupt will occur if enabled. Therefore, the T2EX input may
be used as an additional external interrupt source.
Figure 17.6. T2 Mode 2 Block Diagram
136
Rev. 1.7
C8051F2xx
SFR Definition 17.8. T2CON: Timer 2 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Bit0
SFR Address:
(bit addressable)
0xC8
TF2: Timer 2 Overflow Flag.
Set by hardware when Timer 2 overflows from 0xFFFF to 0x0000. When the Timer 2 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software.
TF2 will not be set when RCLK and/or TCLK are logic 1.
EXF2: Timer 2 External Flag.
Set by hardware when either a capture or reload is caused by a high-to-low transition on the
T2EX input pin and EXEN2 is logic 1. When the Timer 2 interrupt is enabled, setting this bit
causes the CPU to vector to the Timer 2 Interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software.
RCLK: Receive Clock Flag.
Selects which timer is used for the UART's receive clock in modes 1 or 3.
0: Timer 1 overflows used for receive clock.
1: Timer 2 overflows used for receive clock.
TCLK: Transmit Clock Flag.
Selects which timer is used for the UART's transmit clock in modes 1 or 3.
0: Timer 1 overflows used for transmit clock.
1: Timer 2 overflows used for transmit clock.
EXEN2: Timer 2 External Enable.
Enables high-to-low transitions on T2EX to trigger captures or reloads when Timer 2 is not
operating in Baud Rate Generator mode.
0: High-to-low transitions on T2EX ignored.
1: High-to-low transitions on T2EX cause a capture or reload.
TR2: Timer 2 Run Control.
This bit enables/disables Timer 2.
0: Timer 2 disabled.
1: Timer 2 enabled.
C/T2: Counter/Timer Select.
0: Timer Function: Timer 2 incremented by clock defined by T2M (CKCON.5).
1: Counter Function: Timer 2 incremented by high-to-low transitions on external input pin
P0.6/T2.
CP/RL2: Capture/Reload Select.
This bit selects whether Timer 2 functions in capture or auto-reload mode. EXEN2 must be
logic 1 for high-to-low transitions on T2EX to be recognized and used to trigger captures or
reloads. If RCLK or TCLK is set, this bit is ignored and Timer 2 will function in auto-reload
mode.
0: Auto-reload on Timer 2 overflow or high-to-low transition at T2EX (EXEN2 = 1).
1: Capture on high-to-low transition at T2EX (EXEN2 = 1).
Rev. 1.7
137
C8051F2xx
SFR Definition 17.9. RCAP2L: Timer 2 Capture Register 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:
0xCA
Bits 7–0: RCAP2L: Timer 2 Capture Register Low Byte.
The RCAP2L register captures the low byte of Timer 2 when Timer 2 is configured in capture
mode. When Timer 2 is configured in auto-reload mode, it holds the low byte of the reload
value.
SFR Definition 17.10. RCAP2H: Timer 2 Capture Register High 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:
0xCB
Bits 7–0: RCAP2H: Timer 2 Capture Register High Byte.
The RCAP2H register captures the high byte of Timer 2 when Timer 2 is configured in capture mode. When Timer 2 is configured in auto-reload mode, it holds the high byte of the
reload value.
SFR Definition 17.11. TL2: Timer 2 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:
0xCC
R/W
Reset Value
Bits 7–0: TL2: Timer 2 Low Byte.
The TL2 register contains the low byte of the 16-bit Timer 2.
SFR Definition 17.12. TH2: Timer 2 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bits 7–0: TH2: Timer 2 High Byte.
The TH2 register contains the high byte of the 16-bit Timer 2.
138
Rev. 1.7
Bit1
Bit0
SFR Address:
0xCD
C8051F2xx
18. JTAG
Description
The MCU has an on-chip JTAG interface and logic to support Flash read and write operations and nonintrusive in-circuit debug. The C8051F2xx may be placed in a JTAG test chain in order to maintain only
one JTAG interface in a system for boundary scan of other parts, and still utilize the C8051F2xx debug and
Flash programming. However, the C8051F2xx does NOT support boundary scan and will act as BYPASS
as specified in IEEE 1149.1.
The JTAG interface is implemented via four dedicated pins on the MCU, which are TCK, TMS, TDI, and
TDO. These pins are all 5 volt tolerant.
Through the 16-bit JTAG Instruction Register (IR), five instructions shown in JTAG Register Definition 18.1
can be commanded. These commands can either select the device ID code, or select registers for Flash
programming operations. BYPASS is shown to illustrate its default setting. There are four Data Registers
associated with the Flash read and write operations on the MCU.
JTAG Register Definition 18.1. IR: JTAG Instruction
Reset Value
0x0000
Bit15
Bit0
IR value
0x0004
Instruction
IDCODE
0xFFFF
BYPASS
0x0082
Flash Control
0x0083
Flash Data
0x0084
Flash Address
0x0085
Flash Scale
Description
Selects device ID Register
Selects bypass Data Register and is DEFAULT for the device. Note:
The device does NOT support boundary scan. However, it may be
placed in a scan chain and bypassed in a system of other devices utilizing boundary scan.
Selects FLASHCON Register to control how the interface logic
responds to reads and writes to the FLASHDAT Register
Selects FLASHDAT Register for reads and writes to the Flash memory
Selects FLASHADR Register which holds the address of all Flash read,
write, and erase operations
Selects FLASHSCL Register which controls the prescaler used to generate timing signals for Flash operations
Rev. 1.7
139
C8051F2xx
18.1. Flash Programming Commands
The Flash memory can be programmed directly over the JTAG interface using the Flash Control, Flash
Data, Flash Address, and Flash Scale registers. These Indirect Data Registers are accessed via the JTAG
Instruction Register. Read and write operations on indirect data registers are performed by first setting the
appropriate DR address in the IR register. Each read or write is then initiated by writing the appropriate
Indirect Operation Code (IndOpCode) to the selected data register. Incoming commands to this register
have the following format:
19:18
17:0
IndOpCode
WriteData
IndOpCode: These bit set the operation to perform according to the following table:
IndOpCode
0x
10
11
Operation
Poll
Read
Write
The Poll operation is used to check the Busy bit as described below. Although a Capture-DR is performed,
no Update-DR is allowed for the Poll operation. Since updates are disabled, polling can be accomplished
by shifting in/out a single bit.
The Read operation initiates a read from the register addressed by the DRAddress. Reads can be initiated
by shifting only 2 bits into the indirect register. After the read operation is initiated, polling of the Busy bit
must be performed to determine when the operation is complete.
The write operation initiates a write of WriteData to the register addressed by DRAddress. Registers of
any width up to 18 bits can be written. If the register to be written contains fewer than 18 bits, the data in
WriteData should be left-justified, i.e. its MSB should occupy bit 17 above. This allows shorter registers to
be written in fewer JTAG clock cycles. For example, an 8-bit register could be written by shifting only 10
bits. After a Write is initiated, the Busy bit should be polled to determine when the next operation can be
initiated. The contents of the Instruction Register should not be altered while either a read or write operation is in progress.
Outgoing data from the indirect Data Register has the following format:
19
18:5
0
0
ReadData
Busy
The Busy bit indicates that the current operation is not complete. It goes high when an operation is initiated and returns low when complete. Read and Write commands are ignored while Busy is high. In fact, if
polling for Busy to be low will be followed by another read or write operation, JTAG writes of the next operation can be made while checking for Busy to be low. They will be ignored until Busy is read low, at which
time the new operation will initiate. This bit is placed at bit 0 to allow polling by single-bit shifts. When waiting for a Read to complete and Busy is 0, the following 18 bits can be shifted out to obtain the resulting
data. ReadData is always right-justified. This allows registers shorter than 18 bits to be read using a
reduced number of shifts. For example, the result from a byte-read requires 9 bit shifts (Busy + 8 bits).
140
Rev. 1.7
C8051F2xx
JTAG Register Definition 18.2. FLASHCON: JTAG Flash Control
Reset Value
WRMD3
WRMD2
WRMD1
WRMD0
RDMD3
RDMD2
RDMD1
RDMD0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
00000000
This register determines how the Flash interface logic will respond to reads and writes to the FLASHDAT Register.
Bits7–4: WRMD3–0: Write Mode Select Bits.
The Write Mode Select Bits control how the interface logic responds to writes to the FLASHDAT Register per the following values:
0000: A FLASHDAT write replaces the data in the FLASHDAT register, but is otherwise
ignored.
0001: A FLASHDAT write initiates a write of FLASHDAT into the memory address selected
by the FLASHADR register. FLASHADR is incremented by one when complete.
0010: A FLASHDAT write initiates an erasure (sets all bytes to 0xFF) of the Flash page
containing the address in FLASHADR. FLASHDAT must be 0xA5 for the erase to
occur. FLASHADR is not affected. If FLASHADR = 0x1DFE – 0x1DFF, the entire
user space will be erased (i.e. entire Flash memory except for Reserved area
0x1E00 – 0x1FFF).
(All other values for WRMD3–0 are reserved.)
Bits3–0: RDMD3–0: Read Mode Select Bits.
The Read Mode Select Bits control how the interface logic responds to reads to the FLASHDAT Register per the following values:
0000: A FLASHDAT read provides the data in the FLASHDAT register, but is otherwise
ignored.
0001: A FLASHDAT read initiates a read of the byte addressed by the FLASHADR register
if no operation is currently active. This mode is used for block reads.
0010: A FLASHDAT read initiates a read of the byte addressed by FLASHADR only if no
operation is active and any data from a previous read has already been read from
FLASHDAT. This mode allows single bytes to be read (or the last byte of a block)
without initiating an extra read.
(All other values for RDMD3–0 are reserved.)
JTAG Register Definition 18.3. FLASHADR: JTAG Flash Address
Reset Value
0x0000
Bit15
Bit0
This register holds the address for all JTAG Flash read, write, and erase operations. This register
autoincrements after each read or write, regardless of whether the operation succeeded or failed.
Bits15–0: Flash Operation 16-bit Address.
Rev. 1.7
141
C8051F2xx
JTAG Register Definition 18.4. FLASHDAT: JTAG Flash Data
Reset Value
DATA7 DATA6
Bit9
DATA5
Bit8
DATA4 DATA3 DATA2 DATA1
Bit7
Bit6
Bit5
Bit4
DATA0
FAIL
BUSY
Bit2
Bit1
Bit0
Bit3
0000000000
This register is used to read or write data to the Flash memory across the JTAG interface.
Bits9–2: DATA7–0: Flash Data Byte.
Bit1:
FAIL: Flash Fail Bit.
0:
Previous Flash memory operation was successful.
1:
Previous Flash memory operation failed. Usually indicates the associated memory
location was locked.
Bit0:
BUSY: Flash Busy Bit.
0:
Flash interface logic is not busy.
1:
Flash interface logic is processing a request. Reads or writes while BUSY = 1 will
not initiate another operation
JTAG Register Definition 18.5. FLASHSCL: JTAG Flash Scale
Reset Value
FOSE
FRAE
-
-
FLSCL3
FLSCL2
FLSCL1
FLSCL0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
00000000
This register controls the Flash read timing circuit and the prescaler required to generate the correct
timing for Flash operations.
Bit7:
FOSE: Flash One-Shot Enable Bit.
0: Flash read strobe is a full clock-cycle wide.
1: Flash read strobe is 50nsec.
Bit6:
FRAE: Flash Read Always Bit.
0: The Flash output enable and sense amplifier enable are on only when needed to read the
Flash memory.
1: The Flash output enable and sense amplifier enable are always on. This can be used to
limit the variations in digital supply current due to switching the sense amplifiers, thereby
reducing digitally induced noise.
Bits5–4: UNUSED. Read = 00b, Write = don't care.
Bits3–0: FLSCL3–0: Flash Prescaler Control Bits.
The FLSCL3–0 bits control the prescaler used to generate timing signals for Flash operations. Its value should be written before any Flash write or erase operations are initiated.
The value written should be the smallest integer for which:
FLSCL[3:0] > log2(fSYSCLK / 50kHz)
Where fSYSCLK is the system clock frequency. All Flash read/write/erase operations are
disallowed when FLSCL[3:0] = 1111b.
142
Rev. 1.7
C8051F2xx
18.2. Boundary Scan Bypass and ID Code
The MCU does not support boundary scan (IEEE 1149.1), however, it does support the bypass and ID
code functions. Because the MCU utilizes JTAG for Flash memory programming and debug support, and
other devices in a system may use JTAG boundary scan, the MCU supports being placed in BYPASS so
the user may maintain a single JTAG port for a system. Additionally, the MCU supports an ID code.
18.2.1. BYPASS Instruction
The BYPASS instruction is accessed via the IR. It provides access to the standard 1-bit JTAG Bypass data
register.
18.2.2. IDCODE Instruction
The IDCODE instruction is accessed via the IR. It provides access to the 32-bit Device ID register.
JTAG Register Definition 18.6. DEVICEID: JTAG Device ID
Reset Value
Version
Bit31
Part Number
Bit28 Bit27
Manufacturer ID
Bit12 Bit11
1
Bit1
0xn0000243
Bit0
Version = 0000b (Revision A)
= 0001b (Revision B)
Part Number = 0000 0000 0000 0001b (C8051F206/220/1/6, C8051F230/1/6)
Manufacturer ID = 0010 0100 001b (Silicon Laboratories)
18.3. Debug Support
The MCU has on-chip JTAG and debug circuitry that provide non-intrusive, full speed, in-circuit debug
using the production part installed in the end application using the four pin JTAG I/F. Silicon Labs' debug
system supports inspection and modification of memory and registers, breakpoints, stack tracing, and single stepping. No additional target RAM, program memory, or communications channels are required. All
the digital and analog peripherals are functional and work correctly (remain in sync) while emulating. The
WDT is disabled when the MCU is halted during single stepping or at a breakpoint.
The C8051F2xxDK is a development kit with all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8061F206, C8051F220/1/6 and C8051F230/1/6. The
kit includes an Integrated Development Environment (IDE) which has a debugger and integrated 8051
assembler. It has an RS-232 to JTAG interface module referred to as the EC. The kit also includes RS232 and JTAG cables, and wall-mount power supply.
Rev. 1.7
143
C8051F2xx
DOCUMENT CHANGE LIST
Revision 1.6 to Revision 1.7
•
Updated Table 1.1, “Product Selection Guide,” on page 11.
Revision 1.5 to Revision 1.6
•
144
Table 3.1 on page 24 corrected to show 32 kHz instead of 32 MHz.
Rev. 1.7
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Silicon Labs intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each
specific device, and “Typical” parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon
Labs reserves the right to make changes without further notice to the product information, specifications, and descriptions herein, and does not give warranties as to the
accuracy or completeness of the included information. Without prior notification, Silicon Labs may update product firmware during the manufacturing process for security or
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