C8051F712-GQ [SILICON]
Mixed Signal ISP Flash MCU Family; 混合信号ISP功能的Flash MCU系列
| 型号： | C8051F712-GQ |
| 厂家： | 
SILICON |
| 描述： | Mixed Signal ISP Flash MCU Family |
| 文件： | 总290页 (文件大小：1494K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
C8051F70x/71x
Mixed Signal ISP Flash MCU Family
Analog Peripherals
-
10-Bit ADC
•
•
•
•
•
Up to 500 ksps
Up to 16 external single-ended inputs
VREF from on-chip VREF, external pin or VDD
Internal or external start of conversion source
Built-in temperature sensor
-
Comparator
•
•
Programmable hysteresis and response time
Configurable as interrupt or reset source
Capacitive Sense Interface
-
-
-
-
-
16-bit precision measurement
Up to 32 channels
Auto-scan and compare
Auto-accumulate 4x, 8x, and 16x samples
High conversion speed (40 µs per input)
On-Chip Debug
-
-
-
-
On-chip debug circuitry facilitates full speed, non-
intrusive in-system debug (no emulator required)
Provides breakpoints, single stepping,
inspect/modify memory and registers
Superior performance to emulation systems using
ICE-chips, target pods, and sockets
Low cost, complete development kit
64-Pin TQFP, 48-Pin TQFP, 48-Pin QFN
Temperature Range: –40 to +85 °C
High-Speed 8051 µC Core
-
Pipelined instruction architecture; executes 70% of
instructions in 1 or 2 system clocks
-
-
Up to 25 MIPS throughput with 25 MHz clock
Expanded interrupt handler
ANALOG
PERIPHERALS
DIGITAL I/O
Port 0
Port 1
Port 2
Port 3
Port 4
Port 5
UART
SMBus
SPI
A
10-bit
TEMP
M
U
X
500 ksps
ADC
SENSOR
PCA
Timer 0
Timer 1
Timer 2
Timer 3
+
–
Capacitive
Sense
Port 6.0
– 6.5
VOLTAGE
COMPARATOR
24.5 MHz PRECISION INTERNAL OSCILLATOR
HIGH-SPEED CONTROLLER CORE
512 B RAM
16 kB
ISP FLASH
FLEXIBLE
INTERRUPTS
8051 CPU
(25 MIPS)
DEBUG
32 B EEPROM
POR WDT
CIRCUITRY
Rev. 0.2 2/09
Copyright © 2009 by Silicon Laboratories
C8051F70x/71x
This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
C8051F70x/71x
2
Rev. 0.2
C8051F70x/71x
Table of Contents
1. System Overview ..................................................................................................... 17
2. Ordering Information............................................................................................... 24
3. Pin Definitions.......................................................................................................... 26
4. TQFP-64 Package Specifications ........................................................................... 33
5. TQFP-48 Package Specifications ........................................................................... 35
6. QFN-48 Package Specifications ............................................................................. 37
7. Electrical Characteristics........................................................................................ 40
7.1. Absolute Maximum Specifications..................................................................... 40
7.2. Electrical Characteristics ................................................................................... 41
8. 10-Bit ADC (ADC0, C8051F700/2/4/6/8 and C8051F710/2/4 only)......................... 47
8.1. Output Code Formatting.................................................................................... 48
8.2. 8-Bit Mode ......................................................................................................... 48
8.3. Modes of Operation........................................................................................... 48
8.3.1. Starting a Conversion................................................................................ 48
8.3.2. Tracking Modes......................................................................................... 49
8.3.3. Settling Time Requirements...................................................................... 50
8.4. Programmable Window Detector....................................................................... 54
8.4.1. Window Detector Example........................................................................ 56
8.5. ADC0 Analog Multiplexer .................................................................................. 57
9. Temperature Sensor (C8051F700/2/4/6/8 and C8051F710/2/4 only) .................... 59
9.1. Calibration ......................................................................................................... 59
10. Voltage and Ground Reference Options.............................................................. 61
10.1. External Voltage References........................................................................... 62
10.2. Internal Voltage Reference Options ................................................................ 62
10.3. Analog Ground Reference............................................................................... 62
10.4. Temperature Sensor Enable ........................................................................... 62
11. Voltage Regulator (REG0)..................................................................................... 64
12. Comparator0........................................................................................................... 66
12.1. Comparator Multiplexer ................................................................................... 71
13. Capacitive Sense (CS0)......................................................................................... 73
13.1. Configuring Port Pins as Capacitive Sense Inputs.......................................... 74
13.2. Capacitive Sense Start-Of-Conversion Sources ............................................. 74
13.3. Automatic Scanning......................................................................................... 74
13.4. CS0 Comparator.............................................................................................. 75
13.5. CS0 Conversion Accumulator ......................................................................... 76
13.6. Capacitive Sense Multiplexer .......................................................................... 82
14. CIP-51 Microcontroller........................................................................................... 84
14.1. Instruction Set.................................................................................................. 85
14.1.1. Instruction and CPU Timing .................................................................... 85
14.2. CIP-51 Register Descriptions .......................................................................... 90
15. Memory Organization ............................................................................................ 94
15.1. Program Memory............................................................................................. 95
15.1.1. MOVX Instruction and Program Memory ................................................ 95
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C8051F70x/71x
15.2. EEPROM Memory........................................................................................... 95
15.3. Data Memory................................................................................................... 95
15.3.1. Internal RAM ........................................................................................... 95
15.3.1.1. General Purpose Registers ............................................................ 96
15.3.1.2. Bit Addressable Locations .............................................................. 96
15.3.1.3. Stack............................................................................................... 96
16. External Data Memory Interface and On-Chip XRAM......................................... 97
16.1. Accessing XRAM............................................................................................. 97
16.1.1. 16-Bit MOVX Example ............................................................................ 97
16.1.2. 8-Bit MOVX Example .............................................................................. 97
16.2. Configuring the External Memory Interface..................................................... 98
16.3. Port Configuration............................................................................................ 98
16.4. Multiplexed and Non-multiplexed Selection................................................... 101
16.4.1. Multiplexed Configuration...................................................................... 101
16.4.2. Non-multiplexed Configuration.............................................................. 102
16.5. Memory Mode Selection................................................................................ 103
16.5.1. Internal XRAM Only .............................................................................. 103
16.5.2. Split Mode without Bank Select............................................................. 103
16.5.3. Split Mode with Bank Select.................................................................. 104
16.5.4. External Only......................................................................................... 104
16.6. Timing............................................................................................................ 104
16.6.1. Non-Multiplexed Mode .......................................................................... 106
16.6.1.1. 16-bit MOVX: EMI0CF[4:2] = 101, 110, or 111............................. 106
16.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 101 or 111....... 107
16.6.1.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 110 ....................... 108
16.6.2. Multiplexed Mode.................................................................................. 109
16.6.2.1. 16-bit MOVX: EMI0CF[4:2] = 001, 010, or 011............................. 109
16.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 001 or 011....... 110
16.6.2.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 010 ....................... 111
17. In-System Device Identification.......................................................................... 114
18. Special Function Registers................................................................................. 116
19. Interrupts .............................................................................................................. 123
19.1. MCU Interrupt Sources and Vectors.............................................................. 124
19.1.1. Interrupt Priorities.................................................................................. 124
19.1.2. Interrupt Latency ................................................................................... 124
19.2. Interrupt Register Descriptions...................................................................... 125
19.3. INT0 and INT1 External Interrupts................................................................. 132
20. Flash Memory....................................................................................................... 134
20.1. Programming The Flash Memory.................................................................. 134
20.1.1. Flash Lock and Key Functions.............................................................. 134
20.1.2. Flash Erase Procedure ......................................................................... 134
20.1.3. Flash Write Procedure .......................................................................... 135
20.2. Non-volatile Data Storage ............................................................................. 135
20.3. Security Options ............................................................................................ 135
20.4. Flash Write and Erase Guidelines................................................................. 136
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C8051F70x/71x
20.4.1. VDD Maintenance and the VDD Monitor .............................................. 137
20.4.2. PSWE Maintenance.............................................................................. 137
20.4.3. System Clock ........................................................................................ 138
21. EEPROM ............................................................................................................... 141
21.1. RAM Reads and Writes................................................................................. 141
21.2. Auto Increment .............................................................................................. 141
21.3. Interfacing with the EEPROM........................................................................ 141
21.4. EEPROM Security......................................................................................... 142
22. Power Management Modes................................................................................. 146
22.1. Idle Mode....................................................................................................... 146
22.2. Stop Mode ..................................................................................................... 147
22.3. Suspend Mode .............................................................................................. 147
23. Reset Sources...................................................................................................... 149
23.1. Power-On Reset............................................................................................ 150
23.2. Power-Fail Reset / VDD Monitor ................................................................... 151
23.3. External Reset............................................................................................... 152
23.4. Missing Clock Detector Reset ....................................................................... 152
23.5. Comparator0 Reset ....................................................................................... 153
23.6. Watchdog Timer Reset.................................................................................. 153
23.7. Flash Error Reset .......................................................................................... 153
23.8. Software Reset.............................................................................................. 153
24. Watchdog Timer................................................................................................... 155
24.1. Enable/Reset WDT........................................................................................ 155
24.2. Disable WDT ................................................................................................. 155
24.3. Disable WDT Lockout.................................................................................... 155
24.4. Setting WDT Interval ..................................................................................... 155
25. Oscillators and Clock Selection ......................................................................... 157
25.1. System Clock Selection................................................................................. 157
25.2. Programmable Internal High-Frequency (H-F) Oscillator.............................. 159
25.3. External Oscillator Drive Circuit..................................................................... 161
25.3.1. External Crystal Example...................................................................... 163
25.3.2. External RC Example............................................................................ 164
25.3.3. External Capacitor Example.................................................................. 165
26. Port Input/Output ................................................................................................. 166
26.1. Port I/O Modes of Operation.......................................................................... 167
26.1.1. Port Pins Configured for Analog I/O...................................................... 167
26.1.2. Port Pins Configured For Digital I/O...................................................... 167
26.1.3. Interfacing Port I/O to 5 V Logic............................................................ 168
26.1.4. Increasing Port I/O Drive Strength ........................................................ 169
26.2. Assigning Port I/O Pins to Analog and Digital Functions............................... 169
26.2.1. Assigning Port I/O Pins to Analog Functions ........................................ 169
26.2.2. Assigning Port I/O Pins to Digital Functions.......................................... 170
26.2.3. Assigning Port I/O Pins to External Event Trigger Functions................ 170
26.3. Priority Crossbar Decoder ............................................................................. 171
26.4. Port I/O Initialization ...................................................................................... 173
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C8051F70x/71x
26.5. Port Match ..................................................................................................... 176
26.6. Special Function Registers for Accessing and Configuring Port I/O ............. 178
27. Cyclic Redundancy Check Unit (CRC0)............................................................. 194
27.1. 16-bit CRC Algorithm..................................................................................... 195
27.2. 32-bit CRC Algorithm..................................................................................... 196
27.3. Preparing for a CRC Calculation ................................................................... 197
27.4. Performing a CRC Calculation ...................................................................... 197
27.5. Accessing the CRC0 Result .......................................................................... 197
27.6. CRC0 Bit Reverse Feature............................................................................ 200
28. SMBus................................................................................................................... 202
28.1. Supporting Documents.................................................................................. 203
28.2. SMBus Configuration..................................................................................... 203
28.3. SMBus Operation .......................................................................................... 203
28.3.1. Transmitter Vs. Receiver....................................................................... 204
28.3.2. Arbitration.............................................................................................. 204
28.3.3. Clock Low Extension............................................................................. 204
28.3.4. SCL Low Timeout.................................................................................. 204
28.3.5. SCL High (SMBus Free) Timeout ......................................................... 205
28.4. Using the SMBus........................................................................................... 205
28.4.1. SMBus Configuration Register.............................................................. 205
28.4.2. SMB0CN Control Register .................................................................... 209
28.4.2.1. Software ACK Generation ............................................................ 209
28.4.2.2. Hardware ACK Generation........................................................... 209
28.4.3. Hardware Slave Address Recognition .................................................. 211
28.4.4. Data Register ........................................................................................ 214
28.5. SMBus Transfer Modes................................................................................. 215
28.5.1. Write Sequence (Master) ...................................................................... 215
28.5.2. Read Sequence (Master)...................................................................... 216
28.5.3. Write Sequence (Slave) ........................................................................ 217
28.5.4. Read Sequence (Slave)........................................................................ 218
28.6. SMBus Status Decoding................................................................................ 218
29. Enhanced Serial Peripheral Interface (SPI0) ..................................................... 224
29.1. Signal Descriptions........................................................................................ 225
29.1.1. Master Out, Slave In (MOSI)................................................................. 225
29.1.2. Master In, Slave Out (MISO)................................................................. 225
29.1.3. Serial Clock (SCK) ................................................................................ 225
29.1.4. Slave Select (NSS) ............................................................................... 225
29.2. SPI0 Master Mode Operation........................................................................ 226
29.3. SPI0 Slave Mode Operation.......................................................................... 227
29.4. SPI0 Interrupt Sources .................................................................................. 228
29.5. Serial Clock Phase and Polarity .................................................................... 228
29.6. SPI Special Function Registers..................................................................... 230
30. UART0................................................................................................................... 237
30.1. Enhanced Baud Rate Generation.................................................................. 238
30.2. Operational Modes ........................................................................................ 239
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Rev. 0.2
C8051F70x/71x
30.2.1. 8-Bit UART............................................................................................ 239
30.2.2. 9-Bit UART............................................................................................ 240
30.3. Multiprocessor Communications ................................................................... 241
31. Timers ................................................................................................................... 245
31.1. Timer 0 and Timer 1 ...................................................................................... 247
31.1.1. Mode 0: 13-bit Counter/Timer ............................................................... 247
31.1.2. Mode 1: 16-bit Counter/Timer ............................................................... 248
31.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload..................................... 248
31.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................ 249
31.2. Timer 2 .......................................................................................................... 255
31.2.1. 16-bit Timer with Auto-Reload............................................................... 255
31.2.2. 8-bit Timers with Auto-Reload............................................................... 256
31.3. Timer 3 .......................................................................................................... 261
31.3.1. 16-bit Timer with Auto-Reload............................................................... 261
31.3.2. 8-bit Timers with Auto-Reload............................................................... 262
32. Programmable Counter Array............................................................................. 267
32.1. PCA Counter/Timer ....................................................................................... 268
32.2. PCA0 Interrupt Sources................................................................................. 269
32.3. Capture/Compare Modules ........................................................................... 269
32.3.1. Edge-triggered Capture Mode............................................................... 271
32.3.2. Software Timer (Compare) Mode.......................................................... 272
32.3.3. High-Speed Output Mode ..................................................................... 273
32.3.4. Frequency Output Mode ....................................................................... 274
32.3.5. 8-bit, 9-bit, 10-bit and 11-bit Pulse Width Modulator Modes ............... 275
32.3.5.1. 8-bit Pulse Width Modulator Mode.............................................. 275
32.3.5.2. 9/10/11-bit Pulse Width Modulator Mode.................................... 276
32.3.6. 16-Bit Pulse Width Modulator Mode.................................................... 278
32.4. Register Descriptions for PCA0..................................................................... 279
33. C2 Interface .......................................................................................................... 285
33.1. C2 Interface Registers................................................................................... 285
33.2. C2CK Pin Sharing ......................................................................................... 288
Contact Information................................................................................................... 290
Rev. 0.2
7
C8051F70x/71x
List of Figures
1. System Overview
Figure 1.1. C8051F700/1 Block Diagram ................................................................ 18
Figure 1.2. C8051F702/3 Block Diagram ................................................................ 19
Figure 1.3. C8051F704/5 Block Diagram ................................................................ 20
Figure 1.4. C8051F706/07 Block Diagram .............................................................. 21
Figure 1.5. C8051F708/09/10/11 Block Diagram .................................................... 22
Figure 1.6. C8051F712/13/14/15 Block Diagram .................................................... 23
2. Ordering Information
3. Pin Definitions
Figure 3.1. C8051F7xx-GM TQFP64 Pinout Diagram (Top View) .......................... 30
Figure 3.2. C8051F7xx-GQ QFP48 Pinout Diagram (Top View) ............................. 31
Figure 3.3. C8051F7xx-GQ QFN48 Pinout Diagram (Top View) ............................ 32
4. TQFP-64 Package Specifications
Figure 4.1. TQFP-64 Package Drawing .................................................................. 33
Figure 4.2. TQFP-64 PCB Land Pattern .................................................................. 34
5. TQFP-48 Package Specifications
Figure 5.1. TQFP-48 Package Drawing .................................................................. 35
Figure 5.2. TQFP-48 PCB Land Pattern .................................................................. 36
6. QFN-48 Package Specifications
Figure 6.1. QFN-48 Package Drawing .................................................................... 37
Figure 6.2. QFN-48 PCB Land Pattern .................................................................... 38
7. Electrical Characteristics
8. 10-Bit ADC (ADC0, C8051F700/2/4/6/8 and C8051F710/2/4 only)
Figure 8.1. ADC0 Functional Block Diagram ........................................................... 47
Figure 8.2. 10-Bit ADC Track and Conversion Example Timing ............................. 49
Figure 8.3. ADC0 Equivalent Input Circuits ............................................................. 50
Figure 8.4. ADC Window Compare Example: Right-Justified Data ......................... 56
Figure 8.5. ADC Window Compare Example: Left-Justified Data ........................... 56
Figure 8.6. ADC0 Multiplexer Block Diagram .......................................................... 57
9. Temperature Sensor (C8051F700/2/4/6/8 and C8051F710/2/4 only)
Figure 9.1. Temperature Sensor Transfer Function ................................................ 59
Figure 9.2. Temperature Sensor Error with 1-Point Calibration at 0 Celsius ........... 60
10. Voltage and Ground Reference Options
Figure 10.1. Voltage Reference Functional Block Diagram ..................................... 61
11. Voltage Regulator (REG0)
12. Comparator0
Figure 12.1. Comparator0 Functional Block Diagram ............................................. 66
Figure 12.2. Comparator Hysteresis Plot ................................................................ 67
Figure 12.3. Comparator Input Multiplexer Block Diagram ...................................... 71
13. Capacitive Sense (CS0)
Figure 13.1. CS0 Block Diagram ............................................................................. 73
Figure 13.2. Auto-Scan Example ............................................................................. 75
Figure 13.3. CS0 Multiplexer Block Diagram ........................................................... 82
8
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C8051F70x/71x
14. CIP-51 Microcontroller
Figure 14.1. CIP-51 Block Diagram ......................................................................... 84
15. Memory Organization
Figure 15.1. C8051F70x/71x Memory Map ............................................................. 94
Figure 15.2. Flash Program Memory Map ............................................................... 95
16. External Data Memory Interface and On-Chip XRAM
Figure 16.1. Multiplexed Configuration Example ................................................... 101
Figure 16.2. Non-multiplexed Configuration Example ........................................... 102
Figure 16.3. EMIF Operating Modes ..................................................................... 103
Figure 16.4. Non-multiplexed 16-bit MOVX Timing ............................................... 106
Figure 16.5. Non-multiplexed 8-bit MOVX without Bank Select Timing ................ 107
Figure 16.6. Non-multiplexed 8-bit MOVX with Bank Select Timing ..................... 108
Figure 16.7. Multiplexed 16-bit MOVX Timing ....................................................... 109
Figure 16.8. Multiplexed 8-bit MOVX without Bank Select Timing ........................ 110
Figure 16.9. Multiplexed 8-bit MOVX with Bank Select Timing ............................. 111
17. In-System Device Identification
18. Special Function Registers
19. Interrupts
20. Flash Memory
21. EEPROM
Figure 21.1. EEPROM Block Diagram .................................................................. 141
22. Power Management Modes
23. Reset Sources
Figure 23.1. Reset Sources ................................................................................... 149
Figure 23.2. Power-On and VDD Monitor Reset Timing ....................................... 150
24. Watchdog Timer
25. Oscillators and Clock Selection
Figure 25.1. Oscillator Options .............................................................................. 157
Figure 25.2. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram 164
26. Port Input/Output
Figure 26.1. Port I/O Functional Block Diagram .................................................... 166
Figure 26.2. Port I/O Cell Block Diagram .............................................................. 168
Figure 26.3. Port I/O Overdrive Current ................................................................ 168
Figure 26.4. Crossbar Priority Decoder—Possible Pin Assignments .................... 171
Figure 26.5. Crossbar Priority Decoder Example .................................................. 172
27. Cyclic Redundancy Check Unit (CRC0)
Figure 27.1. CRC0 Block Diagram ........................................................................ 194
28. SMBus
Figure 28.1. SMBus Block Diagram ...................................................................... 202
Figure 28.2. Typical SMBus Configuration ............................................................ 203
Figure 28.3. SMBus Transaction ........................................................................... 204
Figure 28.4. Typical SMBus SCL Generation ........................................................ 206
Figure 28.5. Typical Master Write Sequence ........................................................ 215
Figure 28.6. Typical Master Read Sequence ........................................................ 216
Figure 28.7. Typical Slave Write Sequence .......................................................... 217
Rev. 0.2
9
C8051F70x/71x
Figure 28.8. Typical Slave Read Sequence .......................................................... 218
29. Enhanced Serial Peripheral Interface (SPI0)
Figure 29.1. SPI Block Diagram ............................................................................ 224
Figure 29.2. Multiple-Master Mode Connection Diagram ...................................... 226
Figure 29.3. 3-Wire Single Master and 3-Wire Single Slave Mode
Connection Diagram .......................................................................... 227
Figure 29.4. 4-Wire Single Master Mode and 4-Wire Slave Mode
Connection Diagram .......................................................................... 227
Figure 29.5. Master Mode Data/Clock Timing ....................................................... 229
Figure 29.6. Slave Mode Data/Clock Timing (CKPHA = 0) ................................... 229
Figure 29.7. Slave Mode Data/Clock Timing (CKPHA = 1) ................................... 230
Figure 29.8. SPI Master Timing (CKPHA = 0) ....................................................... 234
Figure 29.9. SPI Master Timing (CKPHA = 1) ....................................................... 234
Figure 29.10. SPI Slave Timing (CKPHA = 0) ....................................................... 235
Figure 29.11. SPI Slave Timing (CKPHA = 1) ....................................................... 235
30. UART0
Figure 30.1. UART0 Block Diagram ...................................................................... 237
Figure 30.2. UART0 Baud Rate Logic ................................................................... 238
Figure 30.3. UART Interconnect Diagram ............................................................. 239
Figure 30.4. 8-Bit UART Timing Diagram .............................................................. 239
Figure 30.5. 9-Bit UART Timing Diagram .............................................................. 240
Figure 30.6. UART Multi-Processor Mode Interconnect Diagram ......................... 241
31. Timers
Figure 31.1. T0 Mode 0 Block Diagram ................................................................. 248
Figure 31.2. T0 Mode 2 Block Diagram ................................................................. 249
Figure 31.3. T0 Mode 3 Block Diagram ................................................................. 250
Figure 31.4. Timer 2 16-Bit Mode Block Diagram ................................................. 255
Figure 31.5. Timer 2 8-Bit Mode Block Diagram ................................................... 256
Figure 31.7. Timer 3 16-Bit Mode Block Diagram ................................................. 261
Figure 31.8. Timer 3 8-Bit Mode Block Diagram ................................................... 262
Figure 31.9. Timer 3 Capture Mode Block Diagram .............................................. 263
32. Programmable Counter Array
Figure 32.1. PCA Block Diagram ........................................................................... 267
Figure 32.2. PCA Counter/Timer Block Diagram ................................................... 268
Figure 32.3. PCA Interrupt Block Diagram ............................................................ 269
Figure 32.4. PCA Capture Mode Diagram ............................................................. 271
Figure 32.5. PCA Software Timer Mode Diagram ................................................. 272
Figure 32.6. PCA High-Speed Output Mode Diagram ........................................... 273
Figure 32.7. PCA Frequency Output Mode ........................................................... 274
Figure 32.8. PCA 8-Bit PWM Mode Diagram ........................................................ 276
Figure 32.9. PCA 9, 10 and 11-Bit PWM Mode Diagram ...................................... 277
Figure 32.10. PCA 16-Bit PWM Mode ................................................................... 278
33. C2 Interface
Figure 33.1. Typical C2CK Pin Sharing ................................................................. 288
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Rev. 0.2
C8051F70x/71x
List of Tables
1. System Overview
2. Ordering Information
Table 2.1. Product Selection Guide ......................................................................... 25
3. Pin Definitions
Table 3.1. Pin Definitions for the C8051F70x/71x ................................................... 26
4. TQFP-64 Package Specifications
Table 4.1. TQFP-64 Package Dimensions .............................................................. 33
Table 4.2. TQFP-64 PCB Land Pattern Dimensions ............................................... 34
5. TQFP-48 Package Specifications
Table 5.1. TQFP-48 Package Dimensions .............................................................. 35
Table 5.2. TQFP-48 PCB Land Pattern Dimensions ............................................... 36
6. QFN-48 Package Specifications
Table 6.1. QFN-48 Package Dimensions ................................................................ 37
Table 6.2. QFN-48 PCB Land Pattern Dimensions ................................................. 39
7. Electrical Characteristics
Table 7.1. Absolute Maximum Ratings .................................................................... 40
Table 7.2. Global Electrical Characteristics ............................................................. 41
Table 7.3. Port I/O DC Electrical Characteristics ..................................................... 42
Table 7.4. Reset Electrical Characteristics .............................................................. 42
Table 7.5. Internal Voltage Regulator Electrical Characteristics ............................. 43
Table 7.6. Flash Electrical Characteristics .............................................................. 43
Table 7.7. Internal High-Frequency Oscillator Electrical Characteristics ................. 43
Table 7.8. Capacitive Sense Electrical Characteristics ........................................... 43
Table 7.9. EEPROM Electrical Characteristics ........................................................ 44
Table 7.10. ADC0 Electrical Characteristics ............................................................ 44
Table 7.11. Power Management Electrical Characteristics ..................................... 45
Table 7.12. Temperature Sensor Electrical Characteristics .................................... 45
Table 7.13. Voltage Reference Electrical Characteristics ....................................... 45
Table 7.14. Comparator Electrical Characteristics .................................................. 46
8. 10-Bit ADC (ADC0, C8051F700/2/4/6/8 and C8051F710/2/4 only)
9. Temperature Sensor (C8051F700/2/4/6/8 and C8051F710/2/4 only)
10. Voltage and Ground Reference Options
11. Voltage Regulator (REG0)
12. Comparator0
13. Capacitive Sense (CS0)
Table 13.1. Operation with Auto-scan and Accumulate .......................................... 76
14. CIP-51 Microcontroller
Table 14.1. CIP-51 Instruction Set Summary .......................................................... 86
15. Memory Organization
16. External Data Memory Interface and On-Chip XRAM
Table 16.1. AC Parameters for External Memory Interface ................................... 112
Table 16.2. EMIF Pinout (C8051F70x/71x) ........................................................... 113
17. In-System Device Identification
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C8051F70x/71x
18. Special Function Registers
Table 18.1. Special Function Register (SFR) Memory Map .................................. 117
Table 18.2. Special Function Registers ................................................................. 118
19. Interrupts
Table 19.1. Interrupt Summary .............................................................................. 125
20. Flash Memory
Table 20.1. Flash Security Summary .................................................................... 136
21. EEPROM
22. Power Management Modes
23. Reset Sources
24. Watchdog Timer
25. Oscillators and Clock Selection
26. Port Input/Output
Table 26.1. Port I/O Assignment for Analog Functions ......................................... 169
Table 26.2. Port I/O Assignment for Digital Functions ........................................... 170
Table 26.3. Port I/O Assignment for External Event Trigger Functions ................. 170
27. Cyclic Redundancy Check Unit (CRC0)
Table 27.1. Example 16-bit CRC Outputs ............................................................. 195
Table 27.2. Example 32-bit CRC Outputs ............................................................. 196
28. SMBus
Table 28.1. SMBus Clock Source Selection .......................................................... 206
Table 28.2. Minimum SDA Setup and Hold Times ................................................ 207
Table 28.3. Sources for Hardware Changes to SMB0CN ..................................... 211
Table 28.4. Hardware Address Recognition Examples (EHACK = 1) ................... 212
Table 28.5. SMBus Status Decoding With Hardware ACK Generation Disabled
(EHACK = 0) ....................................................................................... 219
Table 28.6. SMBus Status Decoding With Hardware ACK Generation Enabled
(EHACK = 1) ....................................................................................... 221
29. Enhanced Serial Peripheral Interface (SPI0)
Table 29.1. SPI Slave Timing Parameters ............................................................ 236
30. UART0
Table 30.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator .............................................. 244
Table 30.2. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator ......................................... 244
31. Timers
32. Programmable Counter Array
Table 32.1. PCA Timebase Input Options ............................................................. 268
Table 32.2. PCA0CPM and PCA0PWM Bit Settings for PCA
Capture/Compare Modules ................................................................ 270
33. C2 Interface
12
Rev. 0.2
C8051F70x/71x
List of Registers
SFR Definition 8.1. ADC0CF: ADC0 Configuration ...................................................... 51
SFR Definition 8.2. ADC0H: ADC0 Data Word MSB .................................................... 52
SFR Definition 8.3. ADC0L: ADC0 Data Word LSB ...................................................... 52
SFR Definition 8.4. ADC0CN: ADC0 Control ................................................................ 53
SFR Definition 8.5. ADC0GTH: ADC0 Greater-Than Data High Byte .......................... 54
SFR Definition 8.6. ADC0GTL: ADC0 Greater-Than Data Low Byte ............................ 54
SFR Definition 8.7. ADC0LTH: ADC0 Less-Than Data High Byte ................................ 55
SFR Definition 8.8. ADC0LTL: ADC0 Less-Than Data Low Byte ................................. 55
SFR Definition 8.9. ADC0MX: AMUX0 Channel Select ................................................ 58
SFR Definition 10.1. REF0CN: Voltage Reference Control .......................................... 63
SFR Definition 11.1. REG0CN: Voltage Regulator Control .......................................... 65
SFR Definition 12.1. CPT0CN: Comparator0 Control ................................................... 69
SFR Definition 12.2. CPT0MD: Comparator0 Mode Selection ..................................... 70
SFR Definition 12.3. CPT0MX: Comparator0 MUX Selection ...................................... 72
SFR Definition 13.1. CS0CN: Capacitive Sense Control .............................................. 77
SFR Definition 13.2. CS0CF: Capacitive Sense Configuration ..................................... 78
SFR Definition 13.3. CS0DH: Capacitive Sense Data High Byte ................................. 79
SFR Definition 13.4. CS0DL: Capacitive Sense Data Low Byte ................................... 79
SFR Definition 13.5. CS0SS: Capacitive Sense Auto-Scan Start Channel .................. 80
SFR Definition 13.6. CS0SE: Capacitive Sense Auto-Scan End Channel ................... 80
SFR Definition 13.7. CS0THH: Capacitive Sense Comparator Threshold High Byte ... 81
SFR Definition 13.8. CS0THL: Capacitive Sense Comparator Threshold Low Byte .... 81
SFR Definition 13.9. CS0MX: Capacitive Sense Mux Channel Select ......................... 83
SFR Definition 14.1. DPL: Data Pointer Low Byte ........................................................ 90
SFR Definition 14.2. DPH: Data Pointer High Byte ....................................................... 90
SFR Definition 14.3. SP: Stack Pointer ......................................................................... 91
SFR Definition 14.4. ACC: Accumulator ....................................................................... 91
SFR Definition 14.5. B: B Register ................................................................................ 92
SFR Definition 14.6. PSW: Program Status Word ........................................................ 93
SFR Definition 16.1. EMI0CN: External Memory Interface Control .............................. 99
SFR Definition 16.2. EMI0CF: External Memory Configuration .................................. 100
SFR Definition 16.3. EMI0TC: External Memory Timing Control ................................ 105
SFR Definition 17.1. HWID: Hardware Identification Byte .......................................... 114
SFR Definition 17.2. DERIVID: Derivative Identification Byte ..................................... 114
SFR Definition 17.3. REVID: Hardware Revision Identification Byte .......................... 115
SFR Definition 18.1. SFRPAGE: SFR Page ............................................................... 118
SFR Definition 19.1. IE: Interrupt Enable .................................................................... 126
SFR Definition 19.2. IP: Interrupt Priority .................................................................... 127
SFR Definition 19.3. EIE1: Extended Interrupt Enable 1 ............................................ 128
SFR Definition 19.4. EIE2: Extended Interrupt Enable 2 ............................................ 129
SFR Definition 19.5. EIP1: Extended Interrupt Priority 1 ............................................ 130
SFR Definition 19.6. EIP2: Extended Interrupt Priority 2 ............................................ 131
SFR Definition 19.7. IT01CF: INT0/INT1 Configuration .............................................. 133
Rev. 0.2
13
C8051F70x/71x
SFR Definition 20.1. PSCTL: Program Store R/W Control ......................................... 139
SFR Definition 20.2. FLKEY: Flash Lock and Key ...................................................... 140
SFR Definition 21.1. EEADDR: EEPROM Byte Address ............................................ 142
SFR Definition 21.2. EEDATA: EEPROM Byte Data .................................................. 143
SFR Definition 21.3. EECNTL: EEPROM Control ...................................................... 144
SFR Definition 21.4. EEKEY: EEPROM Protect Key .................................................. 145
SFR Definition 22.1. PCON: Power Control ................................................................ 148
SFR Definition 23.1. VDM0CN: VDD Monitor Control ................................................ 152
SFR Definition 23.2. RSTSRC: Reset Source ............................................................ 154
SFR Definition 24.1. WDTCN: Watchdog Timer Control ............................................ 156
SFR Definition 25.1. CLKSEL: Clock Select ............................................................... 158
SFR Definition 25.2. OSCICL: Internal H-F Oscillator Calibration .............................. 159
SFR Definition 25.3. OSCICN: Internal H-F Oscillator Control ................................... 160
SFR Definition 25.4. OSCXCN: External Oscillator Control ........................................ 162
SFR Definition 26.1. XBR0: Port I/O Crossbar Register 0 .......................................... 174
SFR Definition 26.2. XBR1: Port I/O Crossbar Register 1 .......................................... 175
SFR Definition 26.3. P0MASK: Port 0 Mask Register ................................................. 176
SFR Definition 26.4. P0MAT: Port 0 Match Register .................................................. 177
SFR Definition 26.5. P1MASK: Port 1 Mask Register ................................................. 177
SFR Definition 26.6. P1MAT: Port 1 Match Register .................................................. 178
SFR Definition 26.7. P0: Port 0 ................................................................................... 179
SFR Definition 26.8. P0MDIN: Port 0 Input Mode ....................................................... 179
SFR Definition 26.9. P0MDOUT: Port 0 Output Mode ................................................ 180
SFR Definition 26.10. P0SKIP: Port 0 Skip ................................................................. 180
SFR Definition 26.11. P0DRV: Port 0 Drive Strength ................................................. 181
SFR Definition 26.12. P1: Port 1 ................................................................................. 181
SFR Definition 26.13. P1MDIN: Port 1 Input Mode ..................................................... 182
SFR Definition 26.14. P1MDOUT: Port 1 Output Mode .............................................. 182
SFR Definition 26.15. P1SKIP: Port 1 Skip ................................................................. 183
SFR Definition 26.16. P1DRV: Port 1 Drive Strength ................................................. 183
SFR Definition 26.17. P2: Port 2 ................................................................................. 184
SFR Definition 26.18. P2MDIN: Port 2 Input Mode ..................................................... 184
SFR Definition 26.19. P2MDOUT: Port 2 Output Mode .............................................. 185
SFR Definition 26.20. P2SKIP: Port 2 Skip ................................................................. 185
SFR Definition 26.21. P2DRV: Port 2 Drive Strength ................................................. 186
SFR Definition 26.22. P3: Port 3 ................................................................................. 186
SFR Definition 26.23. P3MDIN: Port 3 Input Mode ..................................................... 187
SFR Definition 26.24. P3MDOUT: Port 3 Output Mode .............................................. 187
SFR Definition 26.25. P3DRV: Port 3 Drive Strength ................................................. 188
SFR Definition 26.26. P4: Port 4 ................................................................................. 188
SFR Definition 26.27. P4MDIN: Port 4 Input Mode ..................................................... 189
SFR Definition 26.28. P4MDOUT: Port 4 Output Mode .............................................. 189
SFR Definition 26.29. P4DRV: Port 4 Drive Strength ................................................. 190
SFR Definition 26.30. P5: Port 5 ................................................................................. 190
SFR Definition 26.31. P5MDIN: Port 5 Input Mode ..................................................... 191
14
Rev. 0.2
C8051F70x/71x
SFR Definition 26.32. P5MDOUT: Port 5 Output Mode .............................................. 191
SFR Definition 26.33. P5DRV: Port 5 Drive Strength ................................................. 192
SFR Definition 26.34. P6: Port 6 ................................................................................. 192
SFR Definition 26.35. P6MDOUT: Port 6 Output Mode .............................................. 193
SFR Definition 26.36. P6DRV: Port 6 Drive Strength ................................................. 193
SFR Definition 27.1. CRC0CN: CRC0 Control ........................................................... 198
SFR Definition 27.2. CRC0IN: CRC Data Input .......................................................... 199
SFR Definition 27.3. CRC0DATA: CRC Data Output ................................................. 199
SFR Definition 27.4. CRC0AUTO: CRC Automatic Control ........................................ 200
SFR Definition 27.5. CRC0CNT: CRC Automatic Flash Sector Count ....................... 200
SFR Definition 27.6. CRC0FLIP: CRC Bit Flip ............................................................ 201
SFR Definition 28.1. SMB0CF: SMBus Clock/Configuration ...................................... 208
SFR Definition 28.2. SMB0CN: SMBus Control .......................................................... 210
SFR Definition 28.3. SMB0ADR: SMBus Slave Address ............................................ 212
SFR Definition 28.4. SMB0ADM: SMBus Slave Address Mask .................................. 213
SFR Definition 28.5. SMB0DAT: SMBus Data ............................................................ 214
SFR Definition 29.1. SPI0CFG: SPI0 Configuration ................................................... 231
SFR Definition 29.2. SPI0CN: SPI0 Control ............................................................... 232
SFR Definition 29.3. SPI0CKR: SPI0 Clock Rate ....................................................... 233
SFR Definition 29.4. SPI0DAT: SPI0 Data ................................................................. 233
SFR Definition 30.1. SCON0: Serial Port 0 Control .................................................... 242
SFR Definition 30.2. SBUF0: Serial (UART0) Port Data Buffer .................................. 243
SFR Definition 31.1. CKCON: Clock Control .............................................................. 246
SFR Definition 31.2. TCON: Timer Control ................................................................. 251
SFR Definition 31.3. TMOD: Timer Mode ................................................................... 252
SFR Definition 31.4. TL0: Timer 0 Low Byte ............................................................... 253
SFR Definition 31.5. TL1: Timer 1 Low Byte ............................................................... 253
SFR Definition 31.6. TH0: Timer 0 High Byte ............................................................. 254
SFR Definition 31.7. TH1: Timer 1 High Byte ............................................................. 254
SFR Definition 31.8. TMR2CN: Timer 2 Control ......................................................... 258
SFR Definition 31.9. TMR2RLL: Timer 2 Reload Register Low Byte .......................... 259
SFR Definition 31.10. TMR2RLH: Timer 2 Reload Register High Byte ...................... 259
SFR Definition 31.11. TMR2L: Timer 2 Low Byte ....................................................... 260
SFR Definition 31.12. TMR2H Timer 2 High Byte ....................................................... 260
SFR Definition 31.13. TMR3CN: Timer 3 Control ....................................................... 264
SFR Definition 31.14. TMR3RLL: Timer 3 Reload Register Low Byte ........................ 265
SFR Definition 31.15. TMR3RLH: Timer 3 Reload Register High Byte ...................... 265
SFR Definition 31.16. TMR3L: Timer 3 Low Byte ....................................................... 266
SFR Definition 31.17. TMR3H Timer 3 High Byte ....................................................... 266
SFR Definition 32.1. PCA0CN: PCA Control .............................................................. 279
SFR Definition 32.2. PCA0MD: PCA Mode ................................................................ 280
SFR Definition 32.3. PCA0PWM: PCA PWM Configuration ....................................... 281
SFR Definition 32.4. PCA0CPMn: PCA Capture/Compare Mode .............................. 282
SFR Definition 32.5. PCA0L: PCA Counter/Timer Low Byte ...................................... 283
SFR Definition 32.6. PCA0H: PCA Counter/Timer High Byte ..................................... 283
Rev. 0.2
15
C8051F70x/71x
SFR Definition 32.7. PCA0CPLn: PCA Capture Module Low Byte ............................. 284
SFR Definition 32.8. PCA0CPHn: PCA Capture Module High Byte ........................... 284
C2 Register Definition 33.1. C2ADD: C2 Address ...................................................... 285
C2 Register Definition 33.2. DEVICEID: C2 Device ID ............................................... 286
C2 Register Definition 33.3. REVID: C2 Revision ID .................................................. 286
C2 Register Definition 33.4. FPCTL: C2 Flash Programming Control ........................ 287
C2 Register Definition 33.5. FPDAT: C2 Flash Programming Data ............................ 287
16
Rev. 0.2
C8051F70x/71x
1. System Overview
C8051F70x/71x devices are fully integrated, mixed-signal, system-on-a-chip MCUs. Highlighted features
are listed below. Refer to Table 2.1 for specific product feature selection and part ordering numbers.
High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
10-bit 500 ksps Single-ended ADC with 16-channel analog multiplexer and integrated temperature sensor
Precision calibrated 24.5 MHz internal oscillator
16Kb of on-chip Flash memory
512 bytes of on-chip RAM
SMBus/I2C, Enhanced UART, and Enhanced SPI serial interfaces implemented in hardware
Four general-purpose 16-bit timers
Capacitive Sense interface with 32 input channels
Programmable Counter/Timer Array (PCA) with three capture/compare modules
On-chip internal voltage reference
On-chip Watchdog timer
On-chip Power-On Reset and Supply Monitor
On-chip Voltage Comparator
54 general purpose I/O
With on-chip power-on reset, V
monitor, watchdog timer, and clock oscillator, the C8051F70x/71x
DD
devices are truly stand-alone, system-on-a-chip solutions. The Flash memory can be reprogrammed even
in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User
software has complete control of all peripherals, and may individually shut down any or all peripherals for
power savings.
The C8051F70x/71x processors include Silicon Laboratories’ 2-Wire C2 Debug and Programming inter-
face, which allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the pro-
duction MCU installed in the final application. This debug logic supports inspection of memory, viewing and
modification of special function registers, setting breakpoints, single stepping, and run and halt commands.
All analog and digital peripherals are fully functional while debugging using C2. The two C2 interface pins
can be shared with user functions, allowing in-system debugging without occupying package pins.
Each device is specified for 1.8–3.6 V operation over the industrial temperature range (–45 to +85 °C). An
internal LDO is used to supply the processor core voltage at 1.8 V. The Port I/O and RST pins are tolerant
of input signals up to 2 V above the V supply. See Table 2.1 for ordering information. Block diagrams of
DD
the devices in the C8051F70x/71x family are shown in Figure 1.1.
Rev. 0.2
17
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
Timers 0,
1, 2, 3
15 kB Flash Memory
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Reset
256 Byte RAM
Port 1
Drivers
Timer 3 /
RTC
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
256 Byte XRAM
PCA
SPI
32 Bytes EEPROM
P2.0
Port 2
Drivers
C2D
Peripheral Power
. . .
. . .
. . .
. . .
. . .
WDT
SMBus
P2.7
P3.0
SFR
Bus
Port 3
Drivers
Crossbar Control
SYSCLK
P3.7
P4.0
VDD
GND
Regulator
Core Power
External Memory
Interface
Port 4
Drivers
Precision
Internal
Oscillator
P4.7
P5.0
P6
Control
Address
Data
Port 5
Drivers
P4 / P3
P5
External
Clock
Circuit
P5.7
P6.0
XTAL1
XTAL2
Port 6
Drivers
P6.5
System Clock
Configuration
Analog Peripherals
Capacitive
Sense
+
-
Comparator
VDD
VREF
(‘F700 Only)
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.1. C8051F700/1 Block Diagram
18
Rev. 0.2
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
Timers 0,
1, 2, 3
16 kB Flash Memory
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Reset
Port 1
Drivers
Timer 3 /
RTC
256 Byte RAM
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
256 Byte XRAM
PCA
SPI
P2.0
Port 2
Drivers
C2D
Peripheral Power
. . .
. . .
. . .
. . .
. . .
WDT
SMBus
P2.7
P3.0
SFR
Bus
Port 3
Drivers
Crossbar Control
SYSCLK
P3.7
P4.0
VDD
GND
Regulator
Core Power
External Memory
Interface
Port 4
Drivers
Precision
Internal
Oscillator
P4.7
P5.0
P6
Control
Address
Data
Port 5
Drivers
P4 / P3
P5
External
Clock
Circuit
P5.7
P6.0
XTAL1
XTAL2
Port 6
Drivers
P6.5
System Clock
Configuration
Analog Peripherals
Capacitive
Sense
+
-
Comparator
VDD
VREF
(‘F702 Only)
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.2. C8051F702/3 Block Diagram
Rev. 0.2
19
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
Timers 0,
1, 2, 4
15 kB Flash Memory
P1.0
P1.1
P1.2
P1.3
Reset
Port 1
Drivers
256 Byte RAM
Timer 3 /
RTC
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
256 Byte XRAM
P2.0
Port 2
Drivers
. . .
. . .
. . .
. . .
. . .
PCA
SPI
P2.7
P3.0
32 Bytes EEPROM
C2D
Peripheral Power
Port 3
Drivers
WDT
SMBus
P3.7
P4.0
SFR
Bus
Crossbar Control
Port 4
Drivers
SYSCLK
VDD
GND
Regulator
Core Power
P4.3
P5.0
Port 5
Drivers
Precision
Internal
Oscillator
P5.7
P6.0
Port 6
Drivers
External
Clock
Circuit
XTAL1
XTAL2
P6.5
Analog Peripherals
System Clock
Configuration
Capacitive
Sense
+
-
Comparator
VDD
(‘F704 Only)
VREF
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.3. C8051F704/5 Block Diagram
20
Rev. 0.2
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
Timers 0,
1, 2, 4
16 kB Flash Memory
P1.0
P1.1
P1.2
P1.3
Reset
Port 1
Drivers
256 Byte RAM
Timer 3 /
RTC
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
P2.0
256 Byte XRAM
Port 2
Drivers
. . .
. . .
. . .
. . .
. . .
PCA
SPI
P2.7
P3.0
C2D
Peripheral Power
Port 3
Drivers
WDT
SMBus
P3.7
P4.0
SFR
Bus
Crossbar Control
Port 4
Drivers
SYSCLK
VDD
GND
Regulator
Core Power
P4.3
P5.0
Port 5
Drivers
Precision
Internal
Oscillator
P5.7
P6.0
Port 6
Drivers
External
Clock
Circuit
XTAL1
XTAL2
P6.5
Analog Peripherals
System Clock
Configuration
Capacitive
Sense
+
-
Comparator
VDD
(‘F706 Only)
VREF
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.4. C8051F706/07 Block Diagram
Rev. 0.2
21
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
8 kB Flash Memory
Timers 0,
1, 2, 3
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Reset
256 Byte RAM
Port 1
Drivers
Timer 3 /
RTC
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
256 Byte XRAM
PCA
SPI
32 Bytes EEPROM
(‘F708/09 Only)
P2.0
Port 2
Drivers
C2D
Peripheral Power
. . .
. . .
. . .
. . .
. . .
WDT
SMBus
P2.7
P3.0
SFR
Bus
Port 3
Drivers
Crossbar Control
SYSCLK
P3.7
P4.0
VDD
GND
Regulator
Core Power
External Memory
Interface
Port 4
Drivers
Precision
Internal
Oscillator
P4.7
P5.0
P6
Control
Address
Data
Port 5
Drivers
P4 / P3
P5
External
Clock
Circuit
P5.7
P6.0
XTAL1
XTAL2
Port 6
Drivers
P6.5
System Clock
Configuration
Analog Peripherals
Capacitive
Sense
+
-
Comparator
VDD
VREF
(‘F708/10 Only)
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.5. C8051F708/09/10/11 Block Diagram
22
Rev. 0.2
C8051F70x/71x
Port I/O Configuration
CIP-51 8051
Controller Core
P0.0 / VREF
P0.1 / AGND
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
Digital Peripherals
UART
Port 0
Drivers
P0.5
Power On
Reset
P0.6
P0.7
8 kB Flash Memory
Timers 0,
1, 2, 4
P1.0
P1.1
P1.2
P1.3
Reset
Port 1
Drivers
256 Byte RAM
Timer 3 /
RTC
Priority
Crossbar
Decoder
Debug /
Programming
Hardware
C2CK/RST
256 Byte XRAM
P2.0
Port 2
Drivers
. . .
. . .
. . .
. . .
. . .
PCA
SPI
32 Bytes EEPROM
(‘F712/13 Only)
P2.7
P3.0
C2D
Peripheral Power
Port 3
Drivers
WDT
SMBus
P3.7
P4.0
SFR
Bus
Crossbar Control
Port 4
Drivers
SYSCLK
VDD
GND
Regulator
Core Power
P4.3
P5.0
Port 5
Drivers
Precision
Internal
Oscillator
P5.7
P6.0
Port 6
Drivers
External
Clock
Circuit
XTAL1
XTAL2
P6.5
Analog Peripherals
System Clock
Configuration
Capacitive
Sense
+
-
Comparator
VDD
(‘F712/14 Only)
VREF
A
M
U
X
10-bit
500 ksps
ADC
VDD
Temp Sensor
Figure 1.6. C8051F712/13/14/15 Block Diagram
Rev. 0.2
23
C8051F70x/71x
2. Ordering Information
All C8051F70x/71x devices have the following features:
25 MIPS (Peak)
Calibrated Internal Oscillator
SMBus/I2C
UART
Programmable counter array (3 channels)
4 Timers (16-bit)
1 Comparator
Lead-Free (RoHS compliant) package
512 bytes RAM
In addition to the features listed above, each device in the C8051F70x/71x family has a set of features that
vary across the product line. See Table 2.1 for a complete list of the unique feature sets for each device in
the family.
24
Rev. 0.2
C8051F70x/71x
Table 2.1. Product Selection Guide
C8051F700-GQ
C8051F701-GQ
C8051F702-GQ
C8051F703-GQ
C8051F704-GQ
C8051F704-GM
C8051F705-GQ
C8051F705-GM
C8051F706-GQ
C8051F706-GM
C8051F707-GQ
C8051F707-GM
C8051F708-GQ
C8051F709-GQ
C8051F710-GQ
C8051F711-GQ
C8051F712-GQ
C8051F712-GM
C8051F713-GQ
C8051F713-GM
C8051F714-GQ
C8051F714-GM
C8051F715-GQ
C8051F715-GM
54
54
54
54
39
39
39
39
39
39
39
39
54
54
54
54
39
39
39
39
39
39
39
39
32
32
32
32
24
24
24
24
24
24
24
24
32
32
32
32
24
24
24
24
24
24
24
24
15
15
16
16
15
15
15
15
16
16
16
16
8
32
32
-
Y
Y
Y
Y
N
N
N
N
N
N
N
N
Y
Y
Y
Y
N
N
N
N
N
N
N
N
Y
N
Y
N
Y
Y
N
N
Y
Y
N
N
Y
N
Y
N
Y
Y
N
N
Y
Y
N
N
16
-
Y
-
TQFP-64
TQFP-64
TQFP-64
TQFP-64
TQFP-48
QFN-48
16
-
Y
-
-
32
32
32
32
-
16
16
-
Y
Y
-
TQFP-48
QFN-48
-
-
16
16
-
Y
Y
-
TQFP-48
QFN-48
-
-
TQFP-48
QFN-48
-
-
-
32
32
-
16
-
Y
-
TQFP-64
TQFP-64
TQFP-64
TQFP-64
TQFP-48
QFN-48
8
8
16
-
Y
-
8
-
8
32
32
32
32
-
16
16
-
Y
Y
-
8
8
TQFP-48
QFN-48
8
-
-
8
16
16
-
Y
Y
-
TQFP-48
QFN-48
8
-
8
-
TQFP-48
QFN-48
8
-
-
-
Lead finish material on all devices is 100% matte tin (Sn).
Rev. 0.2
25
C8051F70x/71x
3. Pin Definitions
Table 3.1. Pin Definitions for the C8051F70x/71x
Name
64-Pin
48-Pin
Type
Description
Packages Packages
V
8, 24, 41, 8, 20, 44
57
Power Supply Voltage.
Ground.
DD
GND
9, 25, 40, 9, 21, 30,
56
43
RST /
58
45
D I/O Device Reset. Open-drain output of internal POR or V
monitor.
DD
Clock signal for the C2 Debug Interface.
C2CK
C2D
D I/O
59
55
54
53
46
42
41
40
D I/O or Bi-directional data signal for the C2 Debug Interface.
A In
D I/O
P0.0 /
D I/O or Port 0.0.
A In
VREF
P0.1/
A In
External VREF input.
D I/O or Port 0.1.
A In
AGND
P0.2 /
External AGND input.
D I/O or Port 0.2.
A In
XTAL1
P0.3 /
A In
External Clock Pin. This pin can be used for crystal clock
mode.
52
39
D I/O or Port 0.3.
A In
XTAL2
P0.4
A I/O or External Clock Pin. This pin can be used for RC, crystal,
and CMOS clock modes.
D In
51
50
49
38
37
36
D I/O or Port 0.4.
A In
P0.5
D I/O or Port 0.5.
A In
P0.6
D I/O or Port 0.6.
A I
26
Rev. 0.2
C8051F70x/71x
Table 3.1. Pin Definitions for the C8051F70x/71x (Continued)
Name
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
64-Pin
Packages Packages
48-Pin
Type
Description
48
47
46
45
44
43
42
39
38
37
36
35
34
33
32
31
30
35
34
33
32
31
D I/O or Port 0.7.
A In
D I/O or Port 1.0.
A In
D I/O or Port 1.1.
A In
D I/O or Port 1.2.
A In
D I/O or Port 1.3.
A In
D I/O or Port 1.4.
A In
D I/O or Port 1.5.
A In
D I/O or Port 1.6.
A In
D I/O or Port 1.7.
A In
29
28
27
26
25
24
23
22
D I/O or Port 2.0.
A In
Cap Sense input pin 1.
D I/O or Port 2.1.
A In
Cap Sense input pin 2.
D I/O or Port 2.2.
A In
Cap Sense input pin 3.
D I/O or Port 2.3.
A In
Cap Sense input pin 4.
D I/O or Port 2.4.
A In
Cap Sense input pin 5.
D I/O or Port 2.5.
A In
Cap Sense input pin 6.
D I/O or Port 2.6.
A In
Cap Sense input pin 7.
D I/O or Port 2.7.
A In
Cap Sense input pin 8.
Rev. 0.2
27
C8051F70x/71x
Table 3.1. Pin Definitions for the C8051F70x/71x (Continued)
Name
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
P5.0
64-Pin
Packages Packages
48-Pin
Type
Description
29
D I/O or Port 3.0.
A In
Cap Sense input pin 9.
28
27
26
D I/O or Port 3.1.
A In
Cap Sense input pin 10.
D I/O or Port 3.2.
A In
Cap Sense input pin 11.
D I/O or Port 3.3.
A In
Cap Sense input pin 12.
23
22
21
20
19
18
17
16
15
14
13
12
11
19
18
17
16
15
14
13
12
D I/O or Port 3.4.
A In
Cap Sense input pin 13.
D I/O or Port 3.5.
A In
Cap Sense input pin 14.
D I/O or Port 3.6.
A In
Cap Sense input pin 15.
D I/O or Port 3.7.
A In
Cap Sense input pin 16.
D I/O or Port 4.0.
A In
Cap Sense input pin 17.
D I/O or Port 4.1.
A In
Cap Sense input pin 18.
D I/O or Port 4.2.
A In
Cap Sense input pin 19.
D I/O or Port 4.3.
A In
Cap Sense input pin 20.
D I/O or Port 4.4.
A In
Cap Sense input pin 21.
D I/O or Port 4.5.
A In
Cap Sense input pin 22.
D I/O or Port 4.6.
A In
Cap Sense input pin 23.
D I/O or Port 4.7.
A In
Cap Sense input pin 24.
11
D I/O or Port 5.0.
A In
Cap Sense input pin 25.
28
Rev. 0.2
C8051F70x/71x
Table 3.1. Pin Definitions for the C8051F70x/71x (Continued)
Name
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
64-Pin
Packages Packages
48-Pin
Type
Description
10
7
10
7
D I/O or Port 5.0.
A In
Cap Sense input pin 26.
D I/O or Port 5.2.
A In
Cap Sense input pin 27
6
6
D I/O or Port 5.3.
A In
Cap Sense input pin 28.
5
5
D I/O or Port 5.4.
A In
Cap Sense input pin 29.
4
4
D I/O or Port 5.5.
A In
Cap Sense input pin 30.
3
3
D I/O or Port 5.6.
A In
Cap Sense input pin 31.
2
2
D I/O or Port 5.7.
A In
Cap Sense input pin 32.
P6.0
P6.1
P6.2
P6.3
P6.4
P6.5
1
D I/O Port 6.0.
D I/O Port 6.1.
D I/O Port 6.2.
D I/O Port 6.3.
D I/O Port 6.4.
D I/O Port 6.5.
64
63
62
61
60
1
48
47
Rev. 0.2
29
C8051F70x/71x
P6.0
P5.7
P5.6
P5.5
P5.4
P5.3
P5.2
VDD
GND
1
2
3
4
5
6
7
8
9
48 P0.7
47 P1.0
46 P1.1
45 P1.2
44 P1.3
43 P1.4
42 P1.5
41 VDD
40 GND
39 P1.6
38 P1.7
37 P2.0
36 P2.1
35 P2.2
34 P2.3
33 P2.4
C8051F700/01/02/03/08/09/10/11
P5.1 10
P5.0 11
P4.7 12
P4.6 13
P4.5 14
P4.4 15
P4.3 16
Figure 3.1. C8051F7xx-GM TQFP64 Pinout Diagram (Top View)
30
Rev. 0.2
C8051F70x/71x
36
1
2
P6.3
P5.7
P5.6
P5.5
P5.4
P5.3
P5.2
VDD
GND
P5.1
P5.0
P4.3
P0.6
35
P0.7
34
3
P1.0
33
4
P1.1
32
5
P1.2
31
6
P1.3
C8051F704/05/06/07/
30
29
28
27
26
25
7
GND
P2.0
P2.1
P2.2
P2.3
P2.4
12/13/14/15
8
9
10
11
12
Figure 3.2. C8051F7xx-GQ QFP48 Pinout Diagram (Top View)
Rev. 0.2
31
C8051F70x/71x
36
35
34
33
32
31
30
29
28
27
26
25
1
2
P6.3
P5.7
P0.6
P0.7
P5.6
P5.5
P5.4
P5.3
P5.2
VDD
GND
P5.1
P5.0
P1.0
P1.1
P1.2
P1.3
GND
P2.0
P2.1
3
4
5
C8051F704/05/06/07/
12/13/14/15
6
7
8
9
GND (optional)
10
11
12
P2.2
P2.3
P2.4
P4.3
Figure 3.3. C8051F7xx-GQ QFN48 Pinout Diagram (Top View)
32
Rev. 0.2
C8051F70x/71x
4. TQFP-64 Package Specifications
Figure 4.1. TQFP-64 Package Drawing
Table 4.1. TQFP-64 Package Dimensions
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
--
--
--
1.20
0.15
1.05
0.27
0.20
E
E1
L
12.00 BSC.
A1
0.05
0.95
0.17
0.09
10.00 BSC.
A2
1.00
0.45
--
0.60
--
0.75
0.20
0.20
0.08
0.08
7
b
0.22
aaa
bbb
ccc
ddd
Q
c
D
--
--
--
12.00 BSC.
10.00 BSC.
0.50 BSC.
--
--
D1
--
--
e
0
3.5
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This package outline conforms to JEDEC MS-026, variant ACD.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 0.2
33
C8051F70x/71x
Figure 4.2. TQFP-64 PCB Land Pattern
Table 4.2. TQFP-64 PCB Land Pattern Dimensions
Dimension
Min
Max
C1
C2
E
11.30
11.30
11.40
11.40
0.50 BSC
X
0.20
1.40
0.30
1.50
Y
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This land pattern design is based on the IPC-7351 guidelines.
Solder Mask Design
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60m minimum, all the way around the pad.
Stencil Design
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
5. The stencil thickness should be 0.125mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
Card Assembly
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
34
Rev. 0.2
C8051F70x/71x
5. TQFP-48 Package Specifications
Figure 5.1. TQFP-48 Package Drawing
Table 5.1. TQFP-48 Package Dimensions
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
—
—
—
1.20
0.15
1.05
0.27
0.20
E
E1
L
9.00 BSC.
7.00 BSC.
0.60
A1
0.05
0.95
0.17
0.09
A2
1.00
0.45
0.75
b
0.22
aaa
bbb
ccc
ddd
Θ
0.20
c
D
—
0.20
9.00 BSC.
7.00 BSC.
0.50 BSC.
0.08
D1
0.08
e
0°
3.5°
7°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MS-026, variation ABC.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 0.2
35
C8051F70x/71x
Figure 5.2. TQFP-48 PCB Land Pattern
Table 5.2. TQFP-48 PCB Land Pattern Dimensions
Dimension
Min
Max
C1
C2
E
6.80
6.80
6.90
6.90
0.50 BSC
X1
Y1
0.20
0.75
0.30
0.85
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This land pattern design is based on the IPC-7351 guidelines.
Solder Mask Design
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60m minimum, all the way around the pad.
Stencil Design
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
5. The stencil thickness should be 0.125mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
Card Assembly
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
36
Rev. 0.2
C8051F70x/71x
6. QFN-48 Package Specifications
Figure 6.1. QFN-48 Package Drawing
Table 6.1. QFN-48 Package Dimensions
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
0.80
0.00
0.18
0.90
—
1.00
0.05
0.30
E2
L
3.90
0.30
0.00
—
4.00
0.40
—
4.10
0.50
0.10
0.10
0.10
0.05
0.08
A1
b
0.23
L1
D
17.00 BSC.
4.00
aaa
bbb
ccc
ddd
—
D2
3.90
4.10
—
—
e
E
0.50 BSC.
7.00 BSC.
—
—
—
—
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. 3.This drawing conforms to JEDEC outline MO-220, variation VKKD-4 except for features D2 and
L which are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 0.2
37
C8051F70x/71x
Figure 6.2. QFN-48 PCB Land Pattern
38
Rev. 0.2
C8051F70x/71x
Table 6.2. QFN-48 PCB Land Pattern Dimensions
Dimension
Min
Max
e
0.50 BSC
C1
C2
X1
X2
Y1
Y2
6.80
6.80
0.20
4.00
0.75
4.00
6.90
6.90
0.30
4.10
0.85
4.10
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification.
3. This Land Pattern Design is based on IPC-SM-782 guidelines.
4. All dimensions shown are at Maximum Material Condition (MMC). Least Material Condition (LMC) is
calculated based on a Fabrication Allowance of 0.05 mm.
Solder Mask Design
5. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal
pad is to be 60m minimum, all the way around the pad.
Stencil Design
6. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good
solder paste release.
7. The stencil thickness should be 0.125 mm (5 mils).
8. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads.
9. A 3x3 array of 1.2 mm square openings on 1.4 mm pitch should be used for the center ground pad.
Card Assembly
10. A No-Clean, Type-3 solder paste is recommended.
11. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
Rev. 0.2
39
C8051F70x/71x
7. Electrical Characteristics
7.1. Absolute Maximum Specifications
Table 7.1. Absolute Maximum Ratings
Parameter
Conditions
Min
Typ
Max
Units
Ambient temperature under bias
Storage Temperature
–55
–65
–0.3
—
—
—
125
150
°C
°C
V
Voltage on RST or any Port I/O Pin
V
+ 2.0
DD
(except V during programming) with
PP
respect to GND
Voltage on V with respect to GND
VDD > 2.4 V
–0.3
—
7.0
V
PP
during a programming operation
Voltage on V with respect to GND
Regulator in Normal Mode
Regulator in Bypass Mode
–0.3
–0.3
—
—
4.2
1.98
V
V
DD
Maximum Total current through V
and GND
—
—
500
mA
DD
Maximum output current sunk by RST
or any Port pin
—
—
100
mA
Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the devices at those or any other conditions above
those indicated in the operation listings of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
40
Rev. 0.2
C8051F70x/71x
7.2. Electrical Characteristics
Table 7.2. Global Electrical Characteristics
–40 to +85 °C, 25 MHz system clock unless otherwise specified.
Parameter
Conditions
Min
Typ
Max Units
Supply Voltage (Note 1)
Regulator in Normal Mode
Regulator in Bypass Mode
1.8
1.7
3.0
1.8
3.6
1.9
V
V
Digital Supply Current with
CPU Active (Normal Mode,
Note 2)
V
V
V
V
V
V
= 1.8 V, Clock = 25 MHz
= 1.8 V, Clock = 1 MHz
= 1.8 V, Clock = 32 kHz
= 3.0 V, Clock = 25 MHz
= 3.0 V, Clock = 1 MHz
= 3.0 V, Clock = 32 kHz
—
—
—
—
—
—
5.5
1.2
175
6.5
1.3
190
TBD
—
—
TBD
—
—
mA
mA
µA
mA
mA
µA
DD
DD
DD
DD
DD
DD
Digital Supply Current with
CPU Inactive (Idle Mode,
Note 2)
V
V
V
V
V
V
= 1.8 V, Clock = 25 MHz
= 1.8 V, Clock = 1 MHz
= 1.8 V, Clock = 32 kHz
= 3.0 V, Clock = 25 MHz
= 3.0 V, Clock = 1 MHz
= 3.0 V, Clock = 32 kHz
—
—
—
—
—
—
2.5
180
90
3.2
200
110
TBD
—
—
TBD
—
—
mA
µA
µA
mA
µA
µA
DD
DD
DD
DD
DD
DD
Digital Supply Current
(shutdown)
Oscillator not running (stop mode),
Internal Regulator Off
—
—
—
—
–40
0
TBD
—
TBD
TBD
—
µA
µA
µA
V
Oscillator not running (stop or suspend
mode), Internal Regulator On
85
Oscillator not running (stop or suspend
mode), Internal Regulator in Bypass
55
Digital Supply RAM Data
Retention Voltage
TBD
—
Specified Operating Tempera-
ture Range
+85
25
°C
SYSCLK (system clock
frequency)
(Note 3)
—
MHz
Tsysl (SYSCLK low time)
Tsysh (SYSCLK high time)
Notes:
18
18
—
—
—
—
ns
ns
1. Analog performance is not guaranteed when VDD is below 1.8 V.
2. Includes bias current for internal voltage regulator.
3. SYSCLK must be at least 32 kHz to enable debugging.
4. Supply current parameters specified with Memory Power Controller enabled.
Rev. 0.2
41
C8051F70x/71x
Table 7.3. Port I/O DC Electrical Characteristics
VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameters
Conditions
Min
Typ
Max
Units
Output High Voltage High Drive Strength
I
I
I
= –3 mA, Port I/O push-pull
= –10 µA, Port I/O push-pull
= –10 mA, Port I/O push-pull
V
V
- 0.7
- 0.1
—
—
—
- 0.8
DD
—
—
—
V
V
V
OH
OH
OH
DD
DD
V
V
Low Drive Strength
I
I
I
= –1 mA, Port I/O push-pull
= –10 µA, Port I/O push-pull
= –3 mA, Port I/O push-pull
V
V
- 0.7
- 0.1
—
—
—
—
—
—
V
V
V
OH
OH
OH
DD
DD
- 0.8
DD
Output Low Voltage High Drive Strength
I
I
I
= 8.5 mA
= 10 µA
= 25 mA
—
—
—
—
—
1.0
0.6
0.1
—
V
V
V
OL
OL
OL
Low Drive Strength
I
I
I
= 1.4 mA
= 10 µA
= 4 mA
—
—
—
—
—
1.0
—
0.6
0.1
—
V
V
V
OL
OL
OL
Input High Voltage
Input Low Voltage
Input Leakage
Current
0.75 x V
—
V
DD
—
-1
—
—
—
25
0.6
1
50
V
µA
µA
Weak Pullup Off
Weak Pullup On, V = 0 V
IN
Table 7.4. Reset Electrical Characteristics
VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
= 8.5 mA,
Min
Typ
Max
Units
RST Output Low Voltage
I
—
—
0.6
V
OL
V
= 1.8 V to 3.6 V
DD
RST Input High Voltage
RST Input Low Voltage
RST Input Pullup Current
0.75 x V
—
—
—
—
0.3 x V
50
V
DD
V
DD
DD
RST = 0.0 V
—
25
µA
V
V
POR Ramp Time
—
—
1
ms
V
DD
DD
Monitor Threshold (V
)
1.7
1.75
500
1.8
RST
Missing Clock Detector
Timeout
Time from last system clock
rising edge to reset initiation
TBD
TBD
µs
Reset Time Delay
Delay between release of any
reset source and code
execution at location 0x0000
—
TBD
—
TBD
—
µs
µs
Minimum RST Low Time to
Generate a System Reset
15
V
V
Monitor Turn-on Time
Monitor Supply Current
V
= V - 0.1 V
RST
—
—
TBD
25
—
µs
DD
DD
DD
TBD
µA
42
Rev. 0.2
C8051F70x/71x
Table 7.5. Internal Voltage Regulator Electrical Characteristics
V
= 3.0 V, –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
Input Voltage Range
Bias Current
1.8
—
3.6
V
Normal Mode
Bypass Mode
—
—
80
50
TBD
TBD
µA
µA
Table 7.6. Flash Electrical Characteristics
Parameter
Conditions
Min
Typ Max Units
Flash Size (Note 1)
C8051F702/3/6/7
C8051F700/1/4/5
C8051F708/9, C8051F710/1/2/3/4/5
16384
15360
8192
bytes
bytes
bytes
Endurance (Erase/Write)
Erase Cycle Time
TBD
TBD
TBD
TBD
20
—
cycles
ms
25 MHz Clock
25 MHz Clock
TBD
TBD
Write Cycle Time
40
µs
Notes:
1. Includes Security Lock Byte
Table 7.7. Internal High-Frequency Oscillator Electrical Characteristics
VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified. Use factory-calibrated settings.
Parameter
Conditions
Min
Typ
Max Units
Oscillator Frequency
Oscillator Supply Current 25 °C, V = 3.0 V,
IFCN = 11b
24
—
24.5
350
25
TBD
MHz
µA
DD
OSCICN.7 = 1,
OCSICN.5 = 0
Table 7.8. Capacitive Sense Electrical Characteristics
VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Single Conversion
Min
Typ
Max
Units
Conversion Time
35
40
32
1
—
3
20
40
75
130
TBD
50
µs
Channels
fF
Number of Channels
Capacitance per Code
External Capacitive Load
Quantization Noise
(Note 1)
—
—
—
—
—
—
—
—
—
TBD
TBD
TBD
TBD
TBD
TBD
—
pF
fF
fF
µA
µA
µA
fF/V
RMS
Peak-to-Peak
CS module alone, No Cap
CS module alone, Maximum Cap
Wake-on-CS Threshold (Note 2)
Supply Current
Power Supply Rejection
Notes:
1. RMS Noise is equivalent to one standard deviation. Peak-to-peak noise encompasses ±3.3 standard
deviations.
2. Includes only current from regulator, CS module, and MCU in suspend mode.
Rev. 0.2
43
C8051F70x/71x
Table 7.9. EEPROM Electrical Characteristics
VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified. Use factory-calibrated settings.
Parameter
Conditions
Min
Typ
Max
Units
Write to EEPROM from RAM
Read of EEPROM to RAM
Endurance (Writes)
3.0
TBD
TBD
—
ms
µs
cycles
TBD 50 x T
SYSCLK
TBD
TBD
Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
Table 7.10. ADC0 Electrical Characteristics
V
= 3.0 V, VREF = 2.40 V (REFSL=0), –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
10
±0.5
±0.5
0
bits
LSB
Integral Nonlinearity
Differential Nonlinearity
Offset Error
—
—
–2
–2
—
±1
±1
2
Guaranteed Monotonic
LSB
LSB
Full Scale Error
0
2
LSB
Offset Temperature Coefficient
45
—
ppm/°C
Dynamic performance (10 kHz sine-wave single-ended input, 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
56
—
—
60
72
—
—
—
dB
dB
dB
Up to the 5th harmonic
Spurious-Free Dynamic Range
–75
Conversion Rate
SAR Conversion Clock
—
13
11
—
—
—
—
—
—
8.33
—
—
MHz
clocks
clocks
ns
Conversion Time in SAR Clocks 10-bit Mode
8-bit Mode
Track/Hold Acquisition Time
V
V
>= 2.0 V
< 2.0 V
300
2.0
—
—
—
DD
DD
µs
Throughput Rate
500
ksps
Analog Inputs
ADC Input Voltage Range
Sampling Capacitance
0
—
5
3
VREF
—
—
V
1x Gain
0.5x Gain
—
—
—
pF
pF
k
Input Multiplexer Impedance
5
—
Power Specifications
Power Supply Current
Power Supply Rejection
Operating Mode, 500 ksps
—
—
600
–70
TBD
—
µA
dB
44
Rev. 0.2
C8051F70x/71x
Table 7.11. Power Management Electrical Characteristics
VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified. Use factory-calibrated settings.
Parameter
Conditions
Min
Typ
Max
Units
Idle Mode Wake-up time
Suspend Mode Wake-up Time
2
—
—
TBD
3
—
SYSCLKs
ns
Table 7.12. Temperature Sensor Electrical Characteristics
V
= 3.0 V, –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
Linearity
Slope
—
—
—
—
—
TBD
TBD
TBD
TBD
TBD
—
—
—
—
—
°C
mV/°C
µV/°C
mV
Slope Error*
Offset
Temp = 0 °C
Temp = 0 °C
Offset Error*
mV
Note: Represents one standard deviation from the mean.
Table 7.13. Voltage Reference Electrical Characteristics
V
= 1.8 to 3.6 V; –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
Internal High Speed Reference (REFSL[1:0] = 11)
Output Voltage
Temperature Coefficient
Turn-on Time
PSRR
25 °C ambient
TBD
—
1.65
—
TBD
V
TBD ppm/°C
—
—
TBD
—
µs
ppm/V
µA
Includes PSRR of ADC0
—
TBD
200
Supply Current
—
—
External Reference (REF0E = 0)
Input Voltage Range
Input Current
0
—
V
DD
Sample Rate = 500 ksps; VREF = 3.0 V
—
TBD
—
µA
Rev. 0.2
45
C8051F70x/71x
Table 7.14. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
Response Time:
Mode 0, Vcm = 1.5 V
CP0+ – CP0– = 100 mV
CP0+ – CP0– = –100 mV
CP0+ – CP0– = 100 mV
CP0+ – CP0– = –100 mV
CP0+ – CP0– = 100 mV
CP0+ – CP0– = –100 mV
CP0+ – CP0– = 100 mV
CP0+ – CP0– = –100 mV
—
—
—
—
—
—
—
—
—
—
2
120
140
190
290
380
780
1400
4400
1
—
—
—
—
—
—
—
—
4
ns
ns
*
Response Time:
ns
*
Mode 1, Vcm = 1.5 V
ns
Response Time:
ns
*
Mode 2, Vcm = 1.5 V
ns
Response Time:
ns
*
Mode 3, Vcm = 1.5 V
ns
Common-Mode Rejection Ratio
Positive Hysteresis 1
Positive Hysteresis 2
Positive Hysteresis 3
Positive Hysteresis 4
Negative Hysteresis 1
Negative Hysteresis 2
Negative Hysteresis 3
Negative Hysteresis 4
mV/V
mV
mV
mV
mV
mV
mV
mV
mV
V
CP0HYP1–0 = 00
CP0HYP1–0 = 01
CP0HYP1–0 = 10
CP0HYP1–0 = 11
CP0HYN1–0 = 00
CP0HYN1–0 = 01
CP0HYN1–0 = 10
CP0HYN1–0 = 11
0
1
5
10
20
30
1
7
10
10
—
2
20
0
5
10
20
30
7
10
10
–0.25
20
Inverting or Non-Inverting Input
Voltage Range
—
V
+ 0.25
DD
Input Offset Voltage
–7.5
—
7.5
mV
Power Specifications
Power Supply Rejection
Powerup Time
—
—
—
—
—
—
TBD
TBD
25
—
mV/V
µs
—
Supply Current at DC
Mode 0
Mode 1
Mode 2
Mode 3
TBD
TBD
TBD
TBD
µA
10
µA
3
µA
0.5
µA
Note: Vcm is the common-mode voltage on CP0+ and CP0–.
46
Rev. 0.2
C8051F70x/71x
8. 10-Bit ADC (ADC0, C8051F700/2/4/6/8 and C8051F710/2/4 only)
ADC0 on the C8051F700/2/4/6/8 and C8051F710/2/4 is a 500 ksps, 10-bit successive-approximation-reg-
ister (SAR) ADC with integrated track-and-hold, a gain stage programmable to 1x or 0.5x, and a program-
mable window detector. The ADC is fully configurable under software control via Special Function
Registers. The ADC may be configured to measure various different signals using the analog multiplexer
described in Section “8.5. ADC0 Analog Multiplexer” on page 57. The voltage reference for the ADC is
selected as described in Section “9. Temperature Sensor (C8051F700/2/4/6/8 and C8051F710/2/4 only)”
on page 59. The ADC0 subsystem is enabled only when the AD0EN bit in the ADC0 Control register
(ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
ADC0CN
VDD
000
001
010
011
100
101
AD0BUSY (W)
Start
Conversion
Timer 0 Overflow
Timer 2 Overflow
Timer 1 Overflow
CNVSTR Input
Timer 3 Overflow
10-Bit
SAR
AIN
X1 or
X0.5
From
AMUX0
ADC
AMP0GN0
AD0WINT
Window
Compare
Logic
32
ADC0LTH ADC0LTL
ADC0GTH ADC0GTL
ADC0CF
Figure 8.1. ADC0 Functional Block Diagram
Rev. 0.2
47
C8051F70x/71x
8.1. Output Code Formatting
The ADC measures the input voltage with reference to GND. The registers ADC0H and ADC0L contain the
high and low bytes of the output conversion code from the ADC at the completion of each conversion. Data
can be right-justified or left-justified, depending on the setting of the AD0LJST bit. Conversion codes are
represented as 10-bit unsigned integers. Inputs are measured from 0 to VREF x 1023/1024. Example
codes are shown below for both right-justified and left-justified data. Unused bits in the ADC0H and ADC0L
registers are set to 0.
Input Voltage
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
VREF x 1023/1024
VREF x 512/1024
VREF x 256/1024
0
0x03FF
0x0200
0x0100
0x0000
0xFFC0
0x8000
0x4000
0x0000
8.2. 8-Bit Mode
Setting the ADC08BE bit in register ADC0CF to 1 will put the ADC in 8-bit mode. In 8-bit mode, only the 8
MSBs of data are converted, and the ADC0H register holds the results. The AD0LJST bit is ignored for 8-
bit mode. 8-bit conversions take two fewer SAR clock cycles than 10-bit conversions, so the conversion is
completed faster, and a 500 ksps sampling rate can be achieved with a slower SAR clock.
8.3. Modes of Operation
ADC0 has a maximum conversion speed of 500 ksps. The ADC0 conversion clock is a divided version of
the system clock, determined by the AD0SC bits in the ADC0CF register.
8.3.1. Starting a Conversion
A conversion can be initiated in one of six ways, depending on the programmed states of the ADC0 Start of
Conversion Mode bits (AD0CM2–0) in register ADC0CN. Conversions may be initiated by one of the fol-
lowing:
1. Writing a 1 to the AD0BUSY bit of register ADC0CN
2. A Timer 0 overflow (i.e., timed continuous conversions)
3. A Timer 2 overflow
4. A Timer 1 overflow
5. A rising edge on the CNVSTR input signal
6. A Timer 3 overflow
Writing a 1 to AD0BUSY provides software control of ADC0 whereby conversions are performed "on-
demand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is
complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt
flag (AD0INT). When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT) should be
used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT is logic 1.
When Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte overflows are used if
Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. See Section
“31. Timers” on page 245 for timer configuration.
Important Note About Using CNVSTR: The CNVSTR input pin also functions as a Port I/O pin. When the
CNVSTR input is used as the ADC0 conversion source, the associated pin should be skipped by the Digi-
tal Crossbar. See Section “26. Port Input/Output” on page 166 for details on Port I/O configuration.
48
Rev. 0.2
C8051F70x/71x
8.3.2. Tracking Modes
The AD0TM bit in register ADC0CN enables "delayed conversions", and will delay the actual conversion
start by three SAR clock cycles, during which time the ADC will continue to track the input. If AD0TM is left
at logic 0, a conversion will begin immediately, without the extra tracking time. For internal start-of-conver-
sion sources, the ADC will track anytime it is not performing a conversion. When the CNVSTR signal is
used to initiate conversions, ADC0 will track either when AD0TM is logic 1, or when AD0TM is logic 0 and
CNVSTR is held low. See Figure 8.2 for track and convert timing details. Delayed conversion mode is use-
ful when AMUX settings are frequently changed, due to the settling time requirements described in Section
“8.3.3. Settling Time Requirements” on page 50.
A. ADC Timing for External Trigger Source
CNVSTR
(AD0CM[2:0]=1xx)
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15* 16 17
SAR
Clocks
AD0TM=1
Track
Convert
Track
*Conversion Ends at rising edge of 15th clock in 8-bit Mode
1
2 3 4 5 6 7 8 9 10 11 12* 13 14
SAR Clocks
AD0TM=0 N/C
Track
Convert
N/C
*Conversion Ends at rising edge of 12th clock in 8-bit Mode
B. ADC Timing for Internal Trigger Source
Write '1' to AD0BUSY,
Timer 0, Timer 2, Timer 1 Overflow
(AD0CM[2:0]=000, 001, 010, 011)
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15* 16 17
SAR
Clocks
Track
Convert
Track
AD0TM=1
*Conversion Ends at rising edge of 15th clock in 8-bit Mode
1
2 3 4 5 6 7 8 9 10 11 12* 13 14
SAR
Clocks
Track or
Convert
AD0TM=0
Convert
Track
*Conversion Ends at rising edge of 12th clock in 8-bit Mode
Figure 8.2. 10-Bit ADC Track and Conversion Example Timing
Rev. 0.2
49
C8051F70x/71x
8.3.3. Settling Time Requirements
A minimum tracking time is required before each conversion to ensure that an accurate conversion is per-
formed. This tracking time is determined by any series impedance, including the AMUX0 resistance, the
the ADC0 sampling capacitance, and the accuracy required for the conversion. In delayed tracking mode,
three SAR clocks are used for tracking at the start of every conversion. For many applications, these three
SAR clocks will meet the minimum tracking time requirements.
Figure 8.3 shows the equivalent ADC0 input circuit. The required ADC0 settling time for a given settling
accuracy (SA) may be approximated by Equation 8.1. See Table 7.10 for ADC0 minimum settling time
requirements as well as the mux impedance and sampling capacitor values.
2n
SA
------
t = ln
RTOTALCSAMPLE
Equation 8.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
R
is the sum of the AMUX0 resistance and any external source resistance.
TOTAL
n is the ADC resolution in bits (10).
MUX Select
Input Pin
RMUX
CSAMPLE
RCInput= RMUX * CSAMPLE
Note: See electrical specification tables for RMUX and CSAMPLE parameters.
Figure 8.3. ADC0 Equivalent Input Circuits
50
Rev. 0.2
C8051F70x/71x
SFR Definition 8.1. ADC0CF: ADC0 Configuration
Bit
7
6
5
4
3
2
1
0
AD0SC[4:0]
AD0LJST AD08BE AMP0GN0
Name
Type
Reset
R/W
1
R/W
0
R/W
0
R/W
1
1
1
1
1
SFR Address = 0xBC; SFR Page = F
Bit Name
7:3 AD0SC[4:0]
Function
ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in bits AD0SC4–0. SAR Conversion clock
requirements are given in the ADC specification table.
SYSCLK
CLKSAR
----------------------
AD0SC =
– 1
Note: If the Memory Power Controller is enabled (MPCE = '1'), AD0SC must be set to at least
"00001" for proper ADC operation.
2
1
0
AD0LJST
AD08BE
ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
Note: The AD0LJST bit is only valid for 10-bit mode (AD08BE = 0).
8-Bit Mode Enable.
0: ADC operates in 10-bit mode (normal).
1: ADC operates in 8-bit mode.
Note: When AD08BE is set to 1, the AD0LJST bit is ignored.
AMP0GN0
ADC Gain Control Bit.
0: Gain = 0.5
1: Gain = 1
Rev. 0.2
51
C8051F70x/71x
SFR Definition 8.2. ADC0H: ADC0 Data Word MSB
Bit
7
6
5
4
3
2
1
0
ADC0H[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xBE; SFR Page = 0
Bit Name
7:0 ADC0H[7:0]
Function
ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–2 will read 000000b. Bits 1–0 are the upper 2 bits of the 10-
bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 10-bit ADC0 Data
Word.
Note: In 8-bit mode AD0LJST is ignored, and ADC0H holds the 8-bit data word.
SFR Definition 8.3. ADC0L: ADC0 Data Word LSB
Bit
7
6
5
4
3
2
1
0
ADC0L[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xBD; SFR Page = 0
Bit Name
7:0 ADC0L[7:0]
Function
ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 10-bit Data Word.
For AD0LJST = 1: Bits 7–6 are the lower 2 bits of the 10-bit Data Word. Bits 5–0 will
always read 0.
Note: In 8-bit mode AD0LJST is ignored, and ADC0L will read back 00000000b.
52
Rev. 0.2
C8051F70x/71x
SFR Definition 8.4. ADC0CN: ADC0 Control
Bit
7
6
5
4
3
2
1
0
AD0EN
AD0TM
AD0INT AD0BUSY AD0WINT
AD0CM[2:0]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0xE8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
AD0EN
ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
6
AD0TM
ADC0 Track Mode Bit.
0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a con-
version is in progress. Conversion begins immediately on start-of-conversion event,
as defined by AD0CM[2:0].
1: Delayed Track Mode: When ADC0 is enabled, input is tracked when a conversion
is not in progress. A start-of-conversion signal initiates three SAR clocks of additional
tracking, and then begins the conversion.
5
4
AD0INT
ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since AD0INT was last cleared.
1: ADC0 has completed a data conversion.
AD0BUSY
ADC0 Busy Bit.
Read:
0: ADC0 conversion is not 0: No Effect.
in progress.
1: ADC0 conversion is in sion if AD0CM[2:0] =
progress. 000b
ADC0 Window Compare Interrupt Flag.
Write:
1: Initiates ADC0 Conver-
3
AD0WINT
0: ADC0 Window Comparison Data match has not occurred since this flag was last
cleared.
1: ADC0 Window Comparison Data match has occurred.
2:0 AD0CM[2:0]
ADC0 Start of Conversion Mode Select.
000: ADC0 start-of-conversion source is write of 1 to AD0BUSY.
001: ADC0 start-of-conversion source is overflow of Timer 0.
010: ADC0 start-of-conversion source is overflow of Timer 2.
011: ADC0 start-of-conversion source is overflow of Timer 1.
100: ADC0 start-of-conversion source is rising edge of external CNVSTR.
101: ADC0 start-of-conversion source is overflow of Timer 3.
11x: Reserved.
Rev. 0.2
53
C8051F70x/71x
8.4. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-pro-
grammed limits, and notifies the system when a desired condition is detected. This is especially effective in
an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system
response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in
polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL)
registers hold the comparison values. The window detector flag can be programmed to indicate when mea-
sured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0
Less-Than and ADC0 Greater-Than registers.
SFR Definition 8.5. ADC0GTH: ADC0 Greater-Than Data High Byte
Bit
7
6
5
4
3
2
1
0
ADC0GTH[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xC4; SFR Page = 0
Bit Name
7:0 ADC0GTH[7:0]
Function
ADC0 Greater-Than Data Word High-Order Bits.
SFR Definition 8.6. ADC0GTL: ADC0 Greater-Than Data Low Byte
Bit
7
6
5
4
3
2
1
0
ADC0GTL[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xC3; SFR Page = 0
Bit Name
7:0 ADC0GTL[7:0]
Function
ADC0 Greater-Than Data Word Low-Order Bits.
54
Rev. 0.2
C8051F70x/71x
SFR Definition 8.7. ADC0LTH: ADC0 Less-Than Data High Byte
Bit
7
6
5
4
3
2
1
0
ADC0LTH[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xC6; SFR Page = 0
Bit Name
7:0 ADC0LTH[7:0]
Function
ADC0 Less-Than Data Word High-Order Bits.
SFR Definition 8.8. ADC0LTL: ADC0 Less-Than Data Low Byte
Bit
7
6
5
4
3
2
1
0
ADC0LTL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xC5; SFR Page = 0
Bit Name
7:0 ADC0LTL[7:0]
Function
ADC0 Less-Than Data Word Low-Order Bits.
Rev. 0.2
55
C8051F70x/71x
8.4.1. Window Detector Example
Figure 8.4
shows
two
example
window
comparisons
for
right-justified
data,
with
ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). The input voltage can
range from 0 to VREF x (1023/1024) with respect to GND, and is represented by a 10-bit unsigned integer
value. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word
(ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL
(if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt will be generated if
the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers
(if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 8.5 shows an example using left-justi-
fied data with the same comparison values.
ADC0H:ADC0L
0x03FF
ADC0H:ADC0L
0x03FF
Input Voltage
(AIN - GND)
Input Voltage
(AIN - GND)
VREF x (1023/
1024)
VREF x (1023/
1024)
AD0WINT
not affected
AD0WINT=1
0x0081
0x0081
VREF x (128/1024)
VREF x (64/1024)
0x0080
0x007F
ADC0LTH:ADC0LTL
VREF x (128/1024)
VREF x (64/1024)
0x0080
0x007F
ADC0GTH:ADC0GTL
AD0WINT
not affected
AD0WINT=1
0x0041
0x0040
0x0041
0x0040
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0x003F
0x003F
AD0WINT=1
AD0WINT
not affected
0x0000
0x0000
0
0
Figure 8.4. ADC Window Compare Example: Right-Justified Data
ADC0H:ADC0L
0xFFC0
ADC0H:ADC0L
0xFFC0
Input Voltage
(AIN - GND)
Input Voltage
(AIN - GND)
VREF x (1023/
1024)
VREF x (1023/
1024)
AD0WINT
not affected
AD0WINT=1
0x2040
0x2040
VREF x (128/1024)
VREF x (64/1024)
0x2000
0x1FC0
ADC0LTH:ADC0LTL
VREF x (128/1024)
VREF x (64/1024)
0x2000
0x1FC0
ADC0GTH:ADC0GTL
AD0WINT
not affected
AD0WINT=1
0x1040
0x1000
0x1040
0x1000
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0x0FC0
0x0FC0
AD0WINT=1
AD0WINT
not affected
0x0000
0x0000
0
0
Figure 8.5. ADC Window Compare Example: Left-Justified Data
56
Rev. 0.2
C8051F70x/71x
8.5. ADC0 Analog Multiplexer
ADC0 on the C8051F700/2/4/6/8 and C8051F710/2/4 uses an analog input multiplexer to select the posi-
tive input to the ADC. Any of the following may be selected as the positive input: Port 0 or Port 1 I/O pins,
the on-chip temperature sensor, or the positive power supply (V ). The ADC0 input channel is selected in
DD
the ADC0MX register described in SFR Definition 8.9.
ADC0MX
P0.0
P1.7
AMUX
ADC0
Temp
Sensor
VREG Output
VDD
GND
Figure 8.6. ADC0 Multiplexer Block Diagram
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be config-
ured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set the corresponding bit in register PnMDIN to 0. To force the Crossbar to skip a Port pin, set the
corresponding bit in register PnSKIP to 1. See Section “26. Port Input/Output” on page 166 for more Port
I/O configuration details.
Rev. 0.2
57
C8051F70x/71x
SFR Definition 8.9. ADC0MX: AMUX0 Channel Select
Bit
7
6
5
4
3
2
1
0
AMX0P[3:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
1
1
1
1
1
SFR Address = 0xBB; SFR Page = 0
Bit
Name
Function
7:5
Unused
Unused.
4:0 AMX0P[4:0]
AMUX0 Positive Input Selection.
64-Pin Devices
48-Pin Devices
P0.0
00000:
00001:
00010:
00011:
00100:
00101:
00110:
00111:
01000
P0.0
P0.1
P0.1
P0.2
P0.2
P0.3
P0.3
P0.4
P0.4
P0.5
P0.5
P0.6
P0.6
P0.7
P0.7
P1.0
P1.0
01001
P1.1
P1.1
01010
P1.2
P1.2
01011
P1.3
P1.3
01100
P1.4
Reserved.
Reserved.
Reserved.
Reserved.
Temp Sensor
VREG Output
VDD
01101
P1.5
01110
P1.6
01111
P1.7
10000:
10001:
10010:
10011:
10100 – 11111:
Temp Sensor
VREG Output
VDD
GND
GND
no input selected
58
Rev. 0.2
C8051F70x/71x
9. Temperature Sensor (C8051F700/2/4/6/8 and C8051F710/2/4 only)
An on-chip temperature sensor is included on the C8051F700/2/4/6/8 and C8051F710/2/4 which can be
directly accessed via the ADC multiplexer in single-ended configuration. To use the ADC to measure the
temperature sensor, the ADC mux channel should be configured to connect to the temperature sensor.
The temperature sensor transfer function is shown in Figure 9.1. The output voltage (V
) is the positive
TEMP
ADC input when the ADC multiplexer is set correctly. The TEMPE bit in register REF0CN enables/disables
the temperature sensor, as described in SFR Definition 10.1. While disabled, the temperature sensor
defaults to a high impedance state and any ADC measurements performed on the sensor will result in
meaningless data. Refer to Table 7.12 for the slope and offset parameters of the temperature sensor.
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
Slope (V / deg C)
Offset (V at 0 Celsius)
Temperature
Figure 9.1. Temperature Sensor Transfer Function
9.1. Calibration
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature mea-
surements (see Table 5.1 for linearity specifications). For absolute temperature measurements, offset
and/or gain calibration is recommended. Typically a 1-point (offset) calibration includes the following steps:
1. Control/measure the ambient temperature (this temperature must be known).
2. Power the device, and delay for a few seconds to allow for self-heating.
3. Perform an ADC conversion with the temperature sensor selected as the ADC’s input.
4. Calculate the offset characteristics, and store this value in non-volatile memory for use with subsequent
temperature sensor measurements.
Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 0 °C.
Rev. 0.2
59
C8051F70x/71x
Parameters that affect ADC measurement, in particular the voltage reference value, will also affect temper-
ature measurement.
5.00
4.00
3.00
2.00
1.00
0.00
5.00
4.00
3.00
2.00
1.00
0.00
-1.00
-2.00
-3.00
-4.00
-5.00
-40.00
-20.00
0.00
20.00
40.00
60.00
80.00
-1.00
-2.00
-3.00
-4.00
-5.00
Temperature (degrees C)
Figure 9.2. Temperature Sensor Error with 1-Point Calibration at 0 Celsius
60
Rev. 0.2
C8051F70x/71x
10. Voltage and Ground Reference Options
The voltage reference MUX is configurable to use an externally connected voltage reference, the on-chip
voltage reference, or one of two power supply voltages (see Figure 10.1). The ground reference MUX
allows the ground reference for ADC0 to be selected between the ground pin (GND) or a port pin dedi-
cated to analog ground (P0.1/AGND).
The voltage and ground reference options are configured using the REF0CN SFR described on page 63.
Electrical specifications are can be found in the Electrical Specifications Chapter.
Important Note About the V
and AGND Inputs: Port pins are used as the external V
and AGND
REF
REF
inputs. When using an external voltage reference, P0.0/VREF should be configured as an analog input and
skipped by the Digital Crossbar. When using AGND as the ground reference to ADC0, P0.1/AGND should
be configured as an analog input and skipped by the Digital Crossbar. Refer to Section “26. Port Input/Out-
put” on page 166 for complete Port I/O configuration details. The external reference voltage must be within
the range 0 V
V and the external ground reference must be at the same DC voltage potential as
REF
DD
GND.
REF0CN
To ADC, Internal
Oscillator,
Reference,
TempSensor
EN
EN
Bias Generator
Temp Sensor
IOSCEN
To Analog Mux
VDD
External
Voltage
Reference
Circuit
R1
P0.0/VREF
VDD
00
01
10
11
Internal 1.8V
Regulated Digital Supply
GND
+
Internal 1.65V
High Speed Reference
4.7F
0.1F
GND
0
1
Recommended
Bypass Capacitors
P0.1/AGND
REFGND
Figure 10.1. Voltage Reference Functional Block Diagram
Rev. 0.2
61
C8051F70x/71x
10.1. External Voltage References
To use an external voltage reference, REFSL[1:0] should be set to 00. Bypass capacitors should be added
as recommended by the manufacturer of the external voltage reference.
10.2. Internal Voltage Reference Options
A 1.65 V high-speed reference is included on-chip. The high speed internal reference is selected by setting
REFSL[1:0] to 11. When selected, the high speed internal reference will be automatically enabled on an
as-needed basis by ADC0.
For applications with a non-varying power supply voltage, using the power supply as the voltage reference
can provide ADC0 with added dynamic range at the cost of reduced power supply noise rejection. To use
the 1.8 to 3.6 V power supply voltage (V ) or the 1.8 V regulated digital supply voltage as the reference
DD
source, REFSL[1:0] should be set to 01 or 10, respectively.
10.3. Analog Ground Reference
To prevent ground noise generated by switching digital logic from affecting sensitive analog measure-
ments, a separate analog ground reference option is available. When enabled, the ground reference for
ADC0 is taken from the P0.1/AGND pin. Any external sensors sampled by ADC0 should be referenced to
the P0.1/AGND pin. The separate analog ground reference option is enabled by setting REFGND to 1.
Note that when using this option, P0.1/AGND must be connected to the same potential as GND.
10.4. Temperature Sensor Enable
The TEMPE bit in register REF0CN enables the temperature sensor. While disabled, the temperature sen-
sor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in
meaningless data.
62
Rev. 0.2
C8051F70x/71x
SFR Definition 10.1. REF0CN: Voltage Reference Control
Bit
7
6
5
4
3
2
1
0
REFGND
REFSL
TEMPE
BIASE
Name
Type
Reset
R
0
R
0
R/W
0
R/W
1
R/W
0
R/W
0
R/W
0
R
0
SFR Address = 0xD2; SFR Page = F
Bit
Name
Function
7:6
Unused Unused.
Read = 00b; Write = Don’t Care.
REFGND Analog Ground Reference.
Selects the ADC0 ground reference.
5
0: The ADC0 ground reference is the GND pin.
1: The ADC0 ground reference is the P0.1/AGND pin.
REFSL Voltage Reference Select.
4:3
Selects the ADC0 voltage reference.
00: The ADC0 voltage reference is the P0.0/VREF pin.
01: The ADC0 voltage reference is the VDD pin.
10: The ADC0 voltage reference is the internal 1.8 V digital supply voltage.
11: The ADC0 voltage reference is the internal 1.65 V high speed voltage reference.
TEMPE Temperature Sensor Enable.
2
Enables/Disables the internal temperature sensor.
0: Temperature Sensor Disabled.
1: Temperature Sensor Enabled.
1
0
BIASE
Internal Analog Bias Generator Enable Bit.
0: Internal Bias Generator off.
1: Internal Bias Generator on.
Unused Unused.
Read = 0b; Write = Don’t Care.
Rev. 0.2
63
C8051F70x/71x
11. Voltage Regulator (REG0)
C8051F70x/71x devices include an internal voltage regulator (REG0) to regulate the internal core supply
to 1.8 V from a V
supply of 1.8 to 3.6 V. Two power-saving modes are built into the regulator to help
DD
reduce current consumption in low-power applications. These modes are accessed through the REG0CN
register (SFR Definition 11.1). Electrical characteristics for the on-chip regulator are specified in Table 7.5
on page 43
If an external regulator is used to power the device, the internal regulator may be put into bypass mode
using the BYPASS bit. The internal regulator should never be placed in bypass mode unless an
external 1.8 V regulator is used to supply V . Doing so could cause permanent damage to the
DD
device.
Under default conditions, when the device enters STOP mode the internal regulator will remain on. This
allows any enabled reset source to generate a reset for the device and bring the device out of STOP mode.
For additional power savings, the STOPCF bit can be used to shut down the regulator and the internal
power network of the device when the part enters STOP mode. When STOPCF is set to 1, the RST pin or
a full power cycle of the device are the only methods of generating a reset.
64
Rev. 0.2
C8051F70x/71x
SFR Definition 11.1. REG0CN: Voltage Regulator Control
Bit
7
6
5
4
3
2
1
0
STOPCF BYPASS
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xB9; SFR Page = F
Bit
Name
Function
7
STOPCF Stop Mode Configuration.
This bit configures the regulator’s behavior when the device enters STOP mode.
0: Regulator is still active in STOP mode. Any enabled reset source will reset the
device.
1: Regulator is shut down in STOP mode. Only the RST pin or power cycle can reset
the device.
6
BYPASS Bypass Internal Regulator.
This bit places the regulator in bypass mode, allowing the core to run directly from the
supply pin.
V
DD
0: Normal Mode—Regulator is on and regulates V down to the core voltage.
DD
1: Bypass Mode—Regulator is in bypass mode, and the microcontroller core operates
directly from the V supply voltage.
DD
IMPORTANT: Bypass mode is for use with an external regulator as the supply
voltage only. Never place the regulator in bypass mode when the V supply
DD
voltage is greater than the specifications given in Table 7.1 on page 40. Doing so
may cause permanent damage to the device.
5:0 Reserved Reserved. Must Write 000000b
Rev. 0.2
65
C8051F70x/71x
12. Comparator0
C8051F70x/71x devices include an on-chip programmable voltage comparator, Comparator0, shown in
Figure 12.1.
The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two
outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0), or an asyn-
chronous “raw” output (CP0A). The asynchronous CP0A signal is available even when the system clock is
not active. This allows the Comparator to operate and generate an output with the device in STOP mode.
When assigned to a Port pin, the Comparator output may be configured as open drain or push-pull (see
Section “26.4. Port I/O Initialization” on page 173). Comparator0 may also be used as a reset source (see
Section “23.5. Comparator0 Reset” on page 153).
The Comparator0 inputs are selected by the comparator input multiplexer, as detailed in Section
“12.1. Comparator Multiplexer” on page 71.
CPT0CN
VDD
CP0 +
+
CP0
Comparator
Input Mux
SET
CLR
SET
CLR
D
Q
Q
D
Q
Q
CP0 -
-
Crossbar
(SYNCHRONIZER)
CP0A
GND
Reset
Decision
Tree
CPT0MD
0
1
CP0
Interrupt
CP0EN
EA
CP0RIF
CP0FIF
0
0
1
1
0
1
Figure 12.1. Comparator0 Functional Block Diagram
The Comparator output can be polled in software, used as an interrupt source, and/or routed to a Port pin.
When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system
clock; the asynchronous output is available even in STOP mode (with no system clock active). When dis-
abled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state,
and the power supply to the comparator is turned off. See Section “26.3. Priority Crossbar Decoder” on
page 171 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be
66
Rev. 0.2
C8051F70x/71x
externally driven from –0.25 V to (V ) + 0.25 V without damage or upset. The complete Comparator elec-
DD
trical specifications are given in Section “7. Electrical Characteristics” on page 40.
The Comparator response time may be configured in software via the CPT0MD register (see SFR Defini-
tion 12.2). Selecting a longer response time reduces the Comparator supply current.
CP0+
VIN+
VIN-
+
CP0
_
OUT
CP0-
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
Negative Hysteresis Voltage
INPUTS
(Programmed by CP0HYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Maximum
Negative Hysteresis
Positive Hysteresis
Disabled
Maximum
Positive Hysteresis
Figure 12.2. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPT0CN. The
user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and
negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3–0 in the Comparator Control Register CPT0CN
(shown in SFR Definition 12.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. As shown in Figure 12.2, settings of 20, 10 or 5 mV of negative hysteresis can be pro-
grammed, 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 Inter-
rupt enable and priority control, see Section “19.1. MCU Interrupt Sources and Vectors” on page 124). The
CP0FIF flag is set to logic 1 upon a Comparator falling-edge occurrence, and the CP0RIF flag is set to
logic 1 upon the Comparator rising-edge occurrence. Once set, these bits remain set until cleared by soft-
ware. The Comparator rising-edge interrupt mask is enabled by setting CP0RIE to a logic 1. The
Comparator0 falling-edge interrupt mask is enabled by setting CP0FIE to a logic 1.
Rev. 0.2
67
C8051F70x/71x
The output state of the Comparator can be obtained at any time by reading the CP0OUT bit. The Compar-
ator is enabled by setting the CP0EN bit to logic 1, and is disabled by clearing this bit to logic 0.
Note that false rising edges and falling edges can be detected when the comparator is first powered on or
if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the
rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is
enabled or its mode bits have been changed.
68
Rev. 0.2
C8051F70x/71x
SFR Definition 12.1. CPT0CN: Comparator0 Control
Bit
7
6
5
4
3
2
1
0
CP0EN
CP0OUT
CP0RIF
CP0FIF
CP0HYP[1:0]
R/W
CP0HYN[1:0]
R/W
Name
Type
Reset
R/W
0
R
0
R/W
0
R/W
0
0
0
0
0
SFR Address = 0x9B; SFR Page = 0
Bit
Name
Function
7
CP0EN
Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
6
5
4
CP0OUT
CP0RIF
CP0FIF
Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Comparator0 Rising-Edge Flag. Must be cleared by software.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Comparator0 Falling-Edge Flag. Must be cleared by software.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge has occurred.
3:2 CP0HYP[1:0] Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
1:0 CP0HYN[1:0] Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev. 0.2
69
C8051F70x/71x
SFR Definition 12.2. CPT0MD: Comparator0 Mode Selection
Bit
7
6
5
4
3
2
1
0
CP0RIE
CP0FIE
CP0MD[1:0]
R/W
Name
Type
Reset
R
0
R
0
R/W
0
R/W
0
R
0
R
0
1
0
SFR Address = 0x9D; SFR Page = 0
Bit
Name
Function
7:6
5
Unused
CP0RIE
Unused. Read = 00b, Write = Don’t Care.
Comparator0 Rising-Edge Interrupt Enable.
0: Comparator0 Rising-edge interrupt disabled.
1: Comparator0 Rising-edge interrupt enabled.
4
CP0FIE
Unused
Comparator0 Falling-Edge Interrupt Enable.
0: Comparator0 Falling-edge interrupt disabled.
1: Comparator0 Falling-edge interrupt enabled.
3:2
Unused. Read = 00b, Write = don’t care.
1:0 CP0MD[1:0]
Comparator0 Mode Select.
These bits affect the response time and power consumption for Comparator0.
00: Mode 0 (Fastest Response Time, Highest Power Consumption)
01: Mode 1
10: Mode 2
11: Mode 3 (Slowest Response Time, Lowest Power Consumption)
70
Rev. 0.2
C8051F70x/71x
12.1. Comparator Multiplexer
C8051F70x/71x devices include an analog input multiplexer to connect Port I/O pins to the comparator
inputs. The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 12.3). The CMX0P2–
CMX0P0 bits select the Comparator0 positive input; the CMX0N2–CMX0N0 bits select the Comparator0
negative input. Important Note About Comparator Inputs: The Port pins selected as comparator inputs
should be configured as analog inputs in their associated Port configuration register, and configured to be
skipped by the Crossbar (for details on Port configuration, see Section “26.6. Special Function Registers
for Accessing and Configuring Port I/O” on page 178).
CPT0MX
P1.0
P1.2
P1.4
VDD
P1.6
CP0 +
+
CP0 -
-
P1.1
P1.3
P1.5
P1.7
GND
Figure 12.3. Comparator Input Multiplexer Block Diagram
Rev. 0.2
71
C8051F70x/71x
SFR Definition 12.3. CPT0MX: Comparator0 MUX Selection
Bit
7
6
5
4
3
2
1
0
CMX0N[2:0]
CMX0P[2:0]
Name
Type
Reset
R
0
R/W
0
R
0
R/W
0
0
0
0
0
SFR Address = 0x9F; SFR Page = 0
Bit
Name
Function
7
Unused
Unused. Read = 0b; Write = don’t care.
Comparator0 Negative Input MUX Selection.
64-Pin Devices
6:4 CMX0N[2:0]
48-Pin Devices
P1.1
000
001
010
011
P1.1
P1.3
P1.5
P1.7
P1.3
Reserved.
Reserved.
No input selected.
100-111 No input selected.
Comparator0 Positive Input MUX Selection.
64-Pin Devices
2:0 CMX0P[2:0]
48-Pin Devices
P1.0
000
001
010
011
P1.0
P1.2
P1.4
P1.6
P1.2
Reserved.
Reserved.
No input selected.
100-111 No input selected.
72
Rev. 0.2
C8051F70x/71x
13. Capacitive Sense (CS0)
The Capacitive Sense subsystem uses a capacitance-to-digital circuit to determine the capacitance on a
port pin. The module can take measurements from different port pins using the module’s 32-channel ana-
log multiplexer. The module is enabled only when the CS0EN bit (CS0CN) is set to 1. Otherwise the mod-
ule is in a low-power shutdown state. The module can be configured to take measurements on one port pin
or a group of port pins, using auto-scan. An accumulator can be configured to accumulate multiple conver-
sions on an input channel. Interrupts can be generated when CS0 completes a conversion or when the
measured value crosses a threshold defined in CS0THH:L.
CS0CF
CS0CN
CS0SS
CS0SE
000
001
010
011
100
101
110
111
CS0BUSY (W)
Auto-Scan
Logic
Timer 0 Overflow
Timer 2 Overflow
Timer 1 Overflow
Timer 3 Overflow
Reserved
Initiated continuously
Initiated continuously
when auto-scan
enabled
Start
Conversion
CS0MX
16-Bit
Capacitor to Digital
20-Bit Accumulator
. . .
Converter
CS0DH
CS0DL
Greater Than
Compare Logic
CS0CMPF
CS0THH
CS0THL
Figure 13.1. CS0 Block Diagram
Rev. 0.2
73
C8051F70x/71x
13.1. Configuring Port Pins as Capacitive Sense Inputs
In order for a port pin to be measured by CS0, that port pin must be configured as an analog input (see “26.
Port Input/Output” ). Configuring the input multiplexer to a port pin not configured as an analog input will
cause the capacitive sense comparator to output incorrect measurements.
13.2. Capacitive Sense Start-Of-Conversion Sources
A capacitive sense conversion can be initiated in one of seven ways, depending on the programmed state
of the CS0 start of conversion bits (CS0CF6:4). Conversions may be initiated by one of the following:
1. Writing a 1 to the CS0BUSY bit of register CS0CN
2. Timer 0 overflow
3. Timer 2 overflow
4. Timer 1 overflow
5. Timer 3 overflow
6. Convert continuously
7. Convert continuously with auto-scan enabled
Conversions can be configured to be initiated continuously through one of two methods. CS0 can be con-
figured to convert at a single channel continuously or it can be configured to convert continuously with
auto-scan enabled. When configured to convert continuously, conversions will begin after the CS0BUSY
bit in CS0CF has been set.
An interrupt will be generated if CS0 conversion complete interrupts are enabled by setting the ECSCPT
bit (EIE2.0).
Note: CS0 conversion complete interrupt behavior depends on the settings of the CS0 accumulator. If CS0 is
configured to accumulate multiple conversions on an input channel, a CS0 conversion complete interrupt will
be generated only after the last conversion completes.
13.3. Automatic Scanning
CS0 can be configured to automatically scan a sequence of contiguous CS0 input channels by configuring
and enabling auto-scan. Using auto-scan with the CS0 comparator interrupt enabled allows a system to
detect a change in measured capacitance without requiring any additional dedicated MCU resources.
Auto-scan is enabled by setting the CS0 start-of-conversion bits (CS0CF6:4) to 111b. After enabling auto-
scan, the starting and ending channels should be set to appropriate values in CS0SS and CS0SE, respec-
tively. Writing to CS0SS when auto-scan is enabled will cause the value written to CS0SS to be copied into
CS0MX. After being enabled, writing a 1 to CS0BUSY will start auto-scan conversions. When auto-scan
completes the number of conversions defined in the CS0 accumulator bits (CS0CF1:0) (see “13.5. CS0
Conversion Accumulator” ), auto-scan configures CS0MX to the next highest port pin configured as an
analog input and begins a conversion on that channel. This scan sequence continues until CS0MX
reaches the ending input channel value defined in CS0SE. After one or more conversions have been taken
at this channel, auto-scan configures CS0MX back to the starting input channel. For an example system
configured to use auto-scan, please see Figure “13.2 Auto-Scan Example” on page 75.
Note: Auto-scan attempts one conversion on a CS0MX channel regardless of whether that channel’s port pin has
been configured as an analog input.
74
Rev. 0.2
C8051F70x/71x
If auto-scan is enabled when the device enters suspend mode, auto-scan will remain enabled and running.
This feature allows the device to wake from suspend through CS0 greater-than comparator event on any
configured capacitive sense input included in the auto-scan sequence of inputs.
SFR Configuration:
Enables Capsense0
CS0CN = 0x80
CS0CF = 0x70
Enables Auto-scan
as start-of-
A
D
A
A
D
D
D
D
A
A
D
A
A
A
A
A
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
0
1
conversion source
Sets P2.2 as Auto-
scan starting channel
CS0SS = 0x02
CS0SE = 0x0D
2
3
Sets P3.5 as Auto-
scan ending channel
Scans on channels
not configured as
analog inputs result
in indeterminate
values that cannot
trigger a CS0
4
Configures P2.3,
P2.2, P2.0 as analog
inputs
5
P2MDIN = 0xF2
P3MDIN = 0x04
6
7
Greater Than
Interrupt event
Configures P3.0-P3.1
and P3.3-P3.7 as
analog inputs
8
9
10
11
12
13
14
15
. . .
Figure 13.2. Auto-Scan Example
13.4. CS0 Comparator
The CS0 comparator compares the latest capacitive sense conversion result with the value stored in
CS0THH:CS0THL. If the result is less than or equal to the stored value, the CS0CMPF bit(CS0CN:0) is set
to 0. If the result is greater than the stored value, CS0CMPF is set to 1.
If the CS0 conversion accumulator is configured to accumulate multiple conversions, a comparison will not
be made until the last conversion has been accumulated.
An interrupt will be generated if CS0 greater-than comparator interrupts are enabled by setting the ECS-
GRT bit (EIE2.1) when the comparator sets CS0CMPF to 1.
If auto-scan is running when the comparator sets the CS0CMPF bit, no further auto-scan initiated conver-
sions will start until firmware sets CS0BUSY to 1.
A CS0 greater-than comparator event can wake a device from suspend mode. This feature is useful in sys-
tems configured to continuously sample one or more capacitive sense channels. The device will remain in
the low-power suspend state until the captured value of one of the scanned channels causes a CS0
Rev. 0.2
75
C8051F70x/71x
greater-than comparator event to occur. It is not necessary to have CS0 comparator interrupts enabled in
order to wake a device from suspend with a greater-than event.
For a summary of behavior with different CS0 comparator, auto-scan, and auto accumulator settings,
please see Table 13.1.
13.5. CS0 Conversion Accumulator
CS0 can be configured to accumulate multiple conversions on an input channel. The number of samples to
be accumulated is configured using the CS0ACU1:0 bits (CS0CF1:0). The accumulator can accumulate 1
sample, 4 samples, 8 samples, or 16 samples. After the defined number of samples have been accumu-
lated, the result is converted to a 16-bit value by dividing the 20-bit accumulator by either 1, 4, 8, or 16
(depending on the CS0ACU[1:0] setting) and copied to the CS0DH:CS0DL SFRs.
Table 13.1. Operation with Auto-scan and Accumulate
CS0 Conversion CS0 Greater Than Interrupt
CS0MX Behavior
Complete
Interrupt
Behavior
Behavior
N
N
Y
N
Y
N
CS0INT Interrupt Interrupt serviced after 1 con-
serviced after 1 version completes if value in
conversion com- CS0DH:CS0DL is greater than
pletes CS0THH:CS0THL
CS0MX unchanged.
CS0MX unchanged.
CS0INT Interrupt Interrupt serviced after M con-
serviced after M versions complete if value in
conversions com- 16-bit accumulator is greater
plete
than CS0THH:CS0THL
CS0INT Interrupt
serviced after 1
Interrupt serviced after con- If greater-than comparator detects conver-
version completes if value in
sion value is greater than
conversion com- CS0DH:CS0DL is greater than
CS0THH:CS0THL, CMUX0 is left
pletes
CS0THH:CS0THL;
Auto-Scan stopped
unchanged; otherwise, CMUX0 updates to
the next channel (CS0MX + 1) and wraps
back to CS0SS after passing CS0SE
Y
Y
CS0INT Interrupt Interrupt serviced after M con- If greater-than comparator detects conver-
serviced after M
conversions com- 16-bit accumulator is greater
plete
versions complete if value in
sion value is greater than
CS0THH:CS0THL, CS0MX is left
than CS0THH:CS0THL; Auto- unchanged; otherwise, CS0MX updates to
Scan stopped
the next channel (CS0MX + 1) and wraps
back to CS0SS after passing CS0SE
M = Accumulator setting (1x, 4x, 8x, 16x)
76
Rev. 0.2
C8051F70x/71x
SFR Definition 13.1. CS0CN: Capacitive Sense Control
Bit
7
6
5
4
3
2
1
0
CS0EN
CS0INT CS0BUSY CS0CMPEN
CS0CMPF
Name
Type
Reset
R/W
0
R
0
R/W
0
R/W
0
R/W
0
R
0
R
0
R
0
SFR Address = 0x9A; SFR Page = 0
Bit
Name
Description
7
CS0EN
CS0 Enable.
0: CS0 disabled and in low-power mode.
1: CS0 enabled and ready to convert.
6
5
Unused
CS0INT
Unused. Read = 0b; Write = Don’t care
CS0 Interrupt Flag.
0: CS0 has not completed a data conversion since the last time CS0INT was
cleared.
1: CS0 has completed a data conversion.
This bit is not automatically cleared by hardware.
4
3
CS0BUSY
CS0 Busy.
Read:
0: CS0 conversion is complete or a conversion is not currently in progress.
1: CS0 conversion is in progress.
Write:
0: No effect.
1: Initiates CS0 conversion if CS0CM[2:0] = 000b, 110b, or 111b.
CS0CMPEN CS0 Digital Comparator Enable Bit.
Enables the digital comparator, which compares accumulated CS0 conversion
output to the value stored in CS0THH:CS0THL.
0: CS0 digital comparator disabled.
1: CS0 digital comparator enabled.
2:1
0
Unused
Unused. Read = 00b; Write = Don’t care
CS0CMPF
CS0 Digital Comparator Interrupt Flag.
0: CS0 result is smaller than the value set by CS0THH and CS0THL since the last
time CS0CMPF was cleared.
1: CS0 result is greater than the value set by CS0THH and CS0THL since the last
time CS0CMPF was cleared.
Rev. 0.2
77
C8051F70x/71x
SFR Definition 13.2. CS0CF: Capacitive Sense Configuration
Bit
7
6
5
4
3
2
1
0
CS0CM[2:0]
CS0ACU[1:0]
R/W R/W
Name
Type
Reset
R
0
R/W
0
R/W
0
R/W
0
R
0
R
0
0
0
SFR Address = 0x9E; SFR Page = 0
Bit
Name
Description
Unused. Read = 0b; Write = Don’t care
7
Unused
6:4
CS0CM[2:0] CS0 Start of Conversion Mode Select.
000: Conversion initiated on every write of 1 to CS0BUSY.
001: Conversion initiated on overflow of Timer 0.
010: Conversion initiated on overflow of Timer 2.
011: Conversion initiated on overflow of Timer 1.
100: Conversion initiated on overflow of Timer 3.
101: Reserved.
110: Conversion initiated continuously after writing 1 to CS0BUSY.
111: Auto-scan enabled, conversions initiated continuously after writing 1 to
CS0BUSY.
3:2
Unused
Unused. Read = 00b; Write = Don’t care
1:0 CS0ACU[1:0] CS0 Accumulator Mode Select.
00: Accumulate 1 sample.
01: Accumulate 4 samples.
10: Accumulate 8 samples.
11: Accumulate 16 samples.
78
Rev. 0.2
C8051F70x/71x
SFR Definition 13.3. CS0DH: Capacitive Sense Data High Byte
Bit
7
6
5
4
3
2
1
0
CS0DH[7:0]
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SFR Address = 0xAA; SFR Page = 0
Bit
Name
Description
7:0
CS0DH
CS0 Data High Byte.
Stores the high byte of the last completed 16-bit Capacitive Sense conversion.
SFR Definition 13.4. CS0DL: Capacitive Sense Data Low Byte
Bit
7
6
5
4
3
2
1
0
CS0DL[7:0]
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SFR Address = 0xA9; SFR Page = 0
Bit
Name
Description
7:0
CS0DL
CS0 Data Low Byte.
Stores the low byte of the last completed 16-bit Capacitive Sense conversion.
Rev. 0.2
79
C8051F70x/71x
SFR Definition 13.5. CS0SS: Capacitive Sense Auto-Scan Start Channel
Bit
7
6
5
4
3
2
1
0
CS0SS[4:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0x92; SFR Page = F
Bit
Name
Description
7:5
Unused
Unused. Read = 000b; Write = Don’t care
CS0SS[4:0]
Starting Channel for Auto-Scan.
Sets the first CS0 channel to be selected by the mux for Capacitive Sense conver-
sion when auto-scan is enabled and active.
When auto-scan is enabled, a write to CS0SS will also update CS0MX.
SFR Definition 13.6. CS0SE: Capacitive Sense Auto-Scan End Channel
Bit
7
6
5
4
3
2
1
0
CS0SE[4:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0x93; SFR Page = F
Bit
Name
Description
7:5
Unused
Unused. Read = 000b; Write = Don’t care
CS0SE[4:0]
Ending Channel for Auto-Scan.
Sets the last CS0 channel to be selected by the mux for Capacitive Sense conver-
sion when auto-scan is enabled and active.
80
Rev. 0.2
C8051F70x/71x
SFR Definition 13.7. CS0THH: Capacitive Sense Comparator Threshold High Byte
Bit
7
6
5
4
3
2
1
0
CS0THH[7:0]
R/W R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0x97; SFR Page = 0
Bit Name
7:0 CS0THH[7:0] CS0 Comparator Threshold High Byte.
Description
High byte of the 16-bit value compared to the Capacitive Sense conversion result.
SFR Definition 13.8. CS0THL: Capacitive Sense Comparator Threshold Low Byte
Bit
7
6
5
4
3
2
1
0
CS0THL[7:0]
R/W R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0x96; SFR Page = 0
Bit
Name
CS0THL[7:0] CS0 Comparator Threshold Low Byte.
Low byte of the 16-bit value compared to the Capacitive Sense conversion result.
Description
7:0
Rev. 0.2
81
C8051F70x/71x
13.6. Capacitive Sense Multiplexer
The input multiplexer can be controlled through two methods. The CS0MX register can be written to
through firmware, or the register can be configured automatically using the modules auto-scan functionality
(see “13.3. Automatic Scanning” ).
CS0MX
P2.0
CS0MUX
Capsense0
P5.7
Figure 13.3. CS0 Multiplexer Block Diagram
82
Rev. 0.2
C8051F70x/71x
SFR Definition 13.9. CS0MX: Capacitive Sense Mux Channel Select
Bit
7
6
5
4
3
2
1
0
CS0UC
CS0MX[4:0]
Name
Type
Reset
W/R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0x9C; SFR Page = 0
Bit
Name
Description
7
CS0UC
CS0 Unconnected.
Disconnects CS0 from all port pins, regardless of the selected channel.
0: CS0 connected to port pins
1: CS0 disconnected from port pins
Read = 00b; Write = 00b
6:5
4:0
Reserved
CS0MX[4:0] CS0 Mux Channel Select.
Selects one of the 32 input channels for Capacitive Sense conversion.
Value
64-pin
48-pin
Value
64-pin
48-pin
packages package
packages package
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
10000
10001
10010
10011
10100
10101
10110
10111
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
P5.0
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
P4.0
P4.1
P4.2
P4.3
Reserved.
Reserved.
Reserved.
Reserved.
P5.0
Reserved. 11000
Reserved. 11001
Reserved. 11010
P5.1
P5.2
Reserved
P3.4
11011
11100
11101
11110
11111
P5.3
P5.4
P3.5
P5.5
P3.6
P5.6
P3.7
P5.7
Rev. 0.2
83
C8051F70x/71x
14. CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop soft-
ware. The MCU family has a superset of all the peripherals included with a standard 8051. The CIP-51
also includes on-chip debug hardware (see description in Section 33), and interfaces directly with the ana-
log and digital subsystems providing a complete data acquisition or control-system solution in a single inte-
grated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 14.1 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
Reset Input
Power Management Modes
On-chip Debug Logic
Extended Interrupt Handler
Program and Data Memory Security
Performance
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the stan-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
DATA BUS
ACCUMULATOR
B
REGISTER
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
PSW
SRAM
ALU
DATA BUS
SFR_ADDRESS
SFR_CONTROL
BUFFER
D8
SFR
BUS
INTERFACE
D8
SFR_WRITE_DATA
SFR_READ_DATA
D8
DATA POINTER
PC INCREMENTER
D8
MEM_ADDRESS
MEM_CONTROL
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
PIPELINE
MEMORY
INTERFACE
A16
D8
MEM_WRITE_DATA
MEM_READ_DATA
CONTROL
LOGIC
RESET
CLOCK
SYSTEM_IRQs
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
STOP
IDLE
POWER CONTROL
REGISTER
D8
Figure 14.1. CIP-51 Block Diagram
84
Rev. 0.2
C8051F70x/71x
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has
a total of 109 instructions. The table below shows the total number of instructions that require each execu-
tion time.
Clocks to Execute
1
2
2/3
5
3
3/4
7
4
3
4/5
1
5
2
8
1
Number of Instructions
26
50
14
14.1. Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc-
tion 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 stan-
dard 8051.
14.1.1. 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 14.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
Rev. 0.2
85
C8051F70x/71x
Table 14.1. CIP-51 Instruction Set Summary
Mnemonic
Description
Bytes
Clock
Cycles
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
INC @Ri
DEC A
DEC Rn
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
Add register to A
Add direct byte to A
Add indirect RAM to A
Add immediate to A
Add register to A with carry
Add direct byte to A with carry
Add indirect RAM to A with carry
Add immediate to A with carry
Subtract register from A with borrow
Subtract direct byte from A with borrow
Subtract indirect RAM from A with borrow
Subtract immediate from A with borrow
Increment A
Increment register
Increment direct byte
Increment indirect RAM
Decrement A
Decrement register
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
Divide A by B
Decimal adjust A
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
1
1
2
1
1
1
1
1
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
2
1
1
2
2
1
4
8
1
DA A
Logical Operations
ANL A, Rn
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
1
2
1
2
2
3
1
2
1
2
2
3
1
2
1
2
2
1
2
2
2
2
3
1
2
2
2
2
3
1
2
2
2
2
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
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
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
86
Rev. 0.2
C8051F70x/71x
Table 14.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
Description
Bytes
Clock
Cycles
XRL direct, #data
CLR A
CPL A
RL A
RLC A
RR A
RRC A
SWAP A
Exclusive-OR immediate to direct byte
Clear A
Complement A
Rotate A left
Rotate A left through Carry
Rotate A right
3
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
Rotate A right through Carry
Swap nibbles of A
Data Transfer
MOV A, Rn
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
Move Register to A
Move direct byte to A
Move indirect RAM to A
Move immediate to A
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
1
1
2
2
2
1
2
2
2
2
3
2
3
2
2
2
3
3
3
3
3
3
3
2
2
1
2
2
2
Move A to Register
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
Move direct byte to Register
Move immediate to Register
Move A to direct byte
Move Register to direct byte
Move direct byte to direct byte
Move indirect RAM to direct byte
Move immediate to direct byte
Move A to indirect RAM
Move direct byte to indirect RAM
Move immediate to indirect RAM
Load DPTR with 16-bit constant
Move code byte relative DPTR to A
Move code byte relative PC to A
Move external data (8-bit address) to A
Move A to external data (8-bit address)
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
Pop direct byte from stack
POP direct
XCH A, Rn
XCH A, direct
XCH A, @Ri
Exchange Register with A
Exchange direct byte with A
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
XCHD A, @Ri
Boolean Manipulation
CLR C
Clear Carry
Clear direct bit
Set Carry
Set direct bit
Complement Carry
Complement direct bit
1
2
1
2
1
2
1
2
1
2
1
2
CLR bit
SETB C
SETB bit
CPL C
CPL bit
Rev. 0.2
87
C8051F70x/71x
Table 14.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
Description
Bytes
Clock
Cycles
ANL C, bit
ANL C, /bit
ORL C, bit
ORL C, /bit
MOV C, bit
MOV bit, C
JC rel
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
Jump if Carry is not set
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
2
2
2
2
2
2
2
2
3
3
3
2
2
2
2
2
2
2/3
2/3
3/4
3/4
3/4
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
Program Branching
ACALL addr11
LCALL addr16
RET
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
2
3
1
1
2
3
2
1
2
2
3
3
3
3
4
5
5
3
4
3
3
2/3
2/3
3/4
3/4
3/4
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
Compare immediate to indirect and jump if not
equal
3
4/5
DJNZ Rn, rel
DJNZ direct, rel
NOP
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
2
3
1
2/3
3/4
1
88
Rev. 0.2
C8051F70x/71x
Notes on Registers, Operands and Addressing Modes:
Rn—Register R0–R7 of the currently selected register bank.
@Ri—Data RAM location addressed indirectly through R0 or R1.
rel—8-bit, signed (twos complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct—8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00–
0x7F) or an SFR (0x80–0xFF).
#data—8-bit constant
#data16—16-bit constant
bit—Direct-accessed bit in Data RAM or SFR
addr11—11-bit destination address used by ACALL and AJMP. The destination must be within the
same 2 kB page of program memory as the first byte of the following instruction.
addr16—16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 8 kB program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
Rev. 0.2
89
C8051F70x/71x
14.2. CIP-51 Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should always be written to the value indicated in the SFR description. Future product versions may use
these bits to implement new features in which case the reset value of the bit will be the indicated value,
selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sec-
tions of the data sheet associated with their corresponding system function.
SFR Definition 14.1. DPL: Data Pointer Low Byte
Bit
7
6
5
4
3
2
1
0
DPL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x82; SFR Page = All Pages
Bit
Name
Function
7:0
DPL[7:0] Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR.
SFR Definition 14.2. DPH: Data Pointer High Byte
Bit
7
6
5
4
3
2
1
0
DPH[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x83; SFR Page = All Pages
Bit
Name
Function
7:0
DPH[7:0] Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR.
90
Rev. 0.2
C8051F70x/71x
SFR Definition 14.3. SP: Stack Pointer
Bit
7
6
5
4
3
2
1
0
SP[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
1
1
1
SFR Address = 0x81; SFR Page = All Pages
Bit
Name
Function
7:0
SP[7:0]
Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incre-
mented before every PUSH operation. The SP register defaults to 0x07 after reset.
SFR Definition 14.4. ACC: Accumulator
Bit
7
6
5
4
3
2
1
0
ACC[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xE0; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7:0
ACC[7:0] Accumulator.
This register is the accumulator for arithmetic operations.
Rev. 0.2
91
C8051F70x/71x
SFR Definition 14.5. B: B Register
Bit
7
6
5
4
3
2
1
0
B[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xF0; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7:0
B[7:0]
B Register.
This register serves as a second accumulator for certain arithmetic operations.
92
Rev. 0.2
C8051F70x/71x
SFR Definition 14.6. PSW: Program Status Word
Bit
7
6
5
4
3
2
1
0
CY
AC
F0
RS[1:0]
R/W
OV
F1
PARITY
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R
0
0
0
SFR Address = 0xD0; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
CY
Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a bor-
row (subtraction). It is cleared to logic 0 by all other arithmetic operations.
6
AC
Auxiliary Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a
borrow from (subtraction) the high order nibble. It is cleared to logic 0 by all other arith-
metic operations.
5
F0
User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
4:3
RS[1:0] Register Bank Select.
These bits select which register bank is used during register accesses.
00: Bank 0, Addresses 0x00-0x07
01: Bank 1, Addresses 0x08-0x0F
10: Bank 2, Addresses 0x10-0x17
11: Bank 3, Addresses 0x18-0x1F
2
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.
1
0
F1
User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY Parity Flag.
This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared
if the sum is even.
Rev. 0.2
93
C8051F70x/71x
15. Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. The memory organization of the
C8051F70x/71x device family is shown in Figure 15.1
PROGRAM/DATA MEMORY
(FLASH)
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
C8051F702/3/6/7
0xFF
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Register's
(Direct Addressing Only)
0x3FFF
Lock Byte
0x3FFE
0x80
0x7F
16 K Bytes FLASH
(Direct and Indirect
Addressing)
(In-System
Programmable in 512
Byte Sectors)
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
0x2F
0x0000
Bit Addressable
0x20
0x1F
C8051F700/1/4/5
General Purpose
Registers
0x00
0x3BFF
0x3BFE
Lock Byte
15 K Bytes FLASH
EXTERNAL DATA ADDRESS SPACE
(In-System
Programmable in 512
Byte Sectors)
0xFFFF
0x0000
Same 256 bytes as from
0x0000 to 0x01FF, wrapped
on 256-byte boundaries
C8051F708/9 and
C8051F710/1/2/3/4/5
0x1FFF
0x1FFE
Lock Byte
0x0100
0x00FF
8 K Bytes FLASH
XRAM - 256 Bytes
(accessable using MOVX
instruction)
(In-System
Programmable in 512
Byte Sectors)
0x0000
0x0000
Figure 15.1. C8051F70x/71x Memory Map
94
Rev. 0.2
C8051F70x/71x
15.1. Program Memory
The members of the C8051F70x/71x device family contain 16 kB (C8051F702/3/6/7), 15 kB
(C8051F700/1/4/5), or 8 kB (C8051F708/9 and C8051F710/1/2/3/4/5) of re-programmable Flash memory
that can be used as non-volatile program or data storage. The last byte of user code space is used as the
security lock byte (0x3FFF on 16 kB devices, 0x3BFF on 15 kB devices and 0x1FFF on 8 kB devices).
C8051F702/3/6/7
0x3FFF
0x3FFE
Lock Byte
Lock Byte Page
C8051F700/1/4/5
Lock Byte
0x3E00
0x3BFF
0x3BFE
C8051F708/9 and
Lock Byte Page
C8051F710/1/2/3/4/5
0x1FFF
0x1FFE
0x3A00
Lock Byte
0x1E00
Flash Memory Space
Lock Byte Page
Flash Memory Space
Flash Memory Space
0x0000
0x0000
0x0000
Figure 15.2. Flash Program Memory Map
15.1.1. MOVX Instruction and Program Memory
The MOVX instruction in an 8051 device is typically used to access external data memory. On the
C8051F70x/71x devices, the MOVX instruction is normally used to read and write on-chip XRAM, but can
be re-configured to write and erase on-chip Flash memory space. MOVC instructions are always used to
read Flash memory, while MOVX write instructions are used to erase and write Flash. This Flash access
feature provides a mechanism for the C8051F70x/71x to update program code and use the program mem-
ory space for non-volatile data storage. Refer to Section “20. Flash Memory” on page 134 for further
details.
15.2. EEPROM Memory
The C8051F700/1/4/5/8/9 and C8051F712/3 contain EEPROM emulation hardware, which uses Flash
memory to emulate a 32-byte EEPROM memory space for non-volatile data storage. The EEPROM data is
accessed through a RAM buffer for increased speed. More details about the EEPROM can be found in
Section “21. EEPROM” on page 141.
15.3. Data Memory
The C8051F70x/71x device family includes 512 bytes of RAM data memory. 256 bytes of this memory is
mapped into the internal RAM space of the 8051. 256 bytes of this memory is on-chip “external” memory.
The data memory map is shown in Figure 15.1 for reference.
15.3.1. Internal RAM
There are 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The
lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either
direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00
through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight
Rev. 0.2
95
C8051F70x/71x
byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or
as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 15.1 illustrates the data memory organization of the
C8051F70x/71x.
15.3.1.1. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of gen-
eral-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 14.6). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes
use registers R0 and R1 as index registers.
15.3.1.2. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destina-
tion).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV
C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
15.3.1.3. Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is desig-
nated using the Stack Pointer (SP) 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 regis-
ter (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.
96
Rev. 0.2
C8051F70x/71x
16. External Data Memory Interface and On-Chip XRAM
For C8051F70x/71x devices, 256 B of RAM are included on-chip and mapped into the external data mem-
ory space (XRAM). Additionally, an External Memory Interface (EMIF) is available on the
C8051F700/1/2/3/8/9 and C8051F710/1 devices, which can be used to access off-chip data memories and
memory-mapped devices connected to the GPIO ports. The external memory space may be accessed
using the external move instruction (MOVX) and the data pointer (DPTR), or using the MOVX indirect
addressing mode using R0 or R1. If the MOVX instruction is used with an 8-bit address operand (such as
@R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Reg-
ister (EMI0CN, shown in SFR Definition 16.1).
Note: The MOVX instruction can also be used for writing to the Flash memory. See Section “20. Flash Memory” on
page 134 for details. The MOVX instruction accesses XRAM by default.
16.1. Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms,
both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit
register which contains the effective address of the XRAM location to be read from or written to. The sec-
ond method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM
address. Examples of both of these methods are given below.
16.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the
DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the
accumulator A:
MOV
MOVX
DPTR, #1234h
A, @DPTR
; load DPTR with 16-bit address to read (0x1234)
; load contents of 0x1234 into accumulator A
The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately,
the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and
DPL, which contains the lower 8-bits of DPTR.
16.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits
of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the
effective address to be accessed. The following series of instructions read the contents of the byte at
address 0x1234 into the accumulator A.
MOV
MOV
MOVX
EMI0CN, #12h
R0, #34h
a, @R0
; load high byte of address into EMI0CN
; load low byte of address into R0 (or R1)
; load contents of 0x1234 into accumulator A
Rev. 0.2
97
C8051F70x/71x
16.2. Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps:
1. Configure the Output Modes of the associated port pins as either push-pull or open-drain (push-pull is
most common).
2. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to logic 1).
3. Select Multiplexed mode or Non-multiplexed mode.
4. Select the memory mode (on-chip only, split mode without bank select, split mode with bank select, or
off-chip only).
5. Set up timing to interface with off-chip memory or peripherals.
Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed
mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition .
16.3. Port Configuration
The EMIF pinout is shown in Figure 16.2 on Page 113
The External Memory Interface claims the associated Port pins for memory operations ONLY during the
execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port
pins reverts to the Port latches for those pins. See Section “26. Port Input/Output” on page 166 for more
information about Port operation and configuration. The Port latches should be explicitly configured to
“park” the External Memory Interface pins in a dormant state, most commonly by setting them to a
logic 1.
During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the driv-
ers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output
mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the
External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases,
the output modes of all EMIF pins should be configured for push-pull mode.
98
Rev. 0.2
C8051F70x/71x
SFR Definition 16.1. EMI0CN: External Memory Interface Control
Bit
7
6
5
4
3
2
1
0
Name
Type
Reset
PGSEL[7:0]
R/W
0
0
0
0
0
0
0
0
SFR Address = 0xAA; SFR Page = F
Bit Name
7:0 PGSEL[7:0] XRAM Page Select Bits.
Function
The XRAM Page Select Bits provide the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page of
RAM.
0x00: 0x0000 to 0x00FF
0x01: 0x0100 to 0x01FF
...
0xFE: 0xFE00 to 0xFEFF
0xFF: 0xFF00 to 0xFFFF
Rev. 0.2
99
C8051F70x/71x
SFR Definition 16.2. EMI0CF: External Memory Configuration
Bit
7
6
5
4
3
2
1
0
Name
Type
Reset
EMD2
EMD[1:0]
EALE[1:0]
R
0
R/W
0
0
0
0
0
1
1
SFR Address = 0xC7; SFR Page = F
Bit
7:5
4
Name
Unused
EMD2
Function
Read = 000b; Write = Don’t Care.
EMIF Multiplex Mode Select Bit.
0: EMIF operates in multiplexed address/data mode
1: EMIF operates in non-multiplexed mode (separate address and data pins)
3:2 EMD[1:0] EMIF Operating Mode Select Bits.
00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to
on-chip memory space
01: Split Mode without Bank Select: Accesses below the 256 B boundary are directed
on-chip. Accesses above the 256 B boundary are directed off-chip. 8-bit off-chip MOVX
operations use current contents of the Address high port latches to resolve the upper
address byte. To access off chip space, EMI0CN must be set to a page that is not con-
tained in the on-chip address space.
10: Split Mode with Bank Select: Accesses below the 256 B boundary are directed on-
chip. Accesses above the 256 B boundary are directed off-chip. 8-bit off-chip MOVX
operations uses the contents of EMI0CN to determine the high-byte of the address.
11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to
the CPU.
1:0 EALE[1:0] ALE Pulse-Width Select Bits.
These bits only have an effect when EMD2 = 0.
00: ALE high and ALE low pulse width = 1 SYSCLK cycle.
01: ALE high and ALE low pulse width = 2 SYSCLK cycles.
10: ALE high and ALE low pulse width = 3 SYSCLK cycles.
11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
100
Rev. 0.2
C8051F70x/71x
16.4. Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode,
depending on the state of the EMD2 (EMI0CF.4) bit.
16.4.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins:
AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits
of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is
driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in
Figure 16.1.
In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state
of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are pre-
sented to AD[7:0]. During this phase, the address latch is configured such that the Q outputs reflect the
states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch
outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data
Bus controls the state of the AD[7:0] port at the time RD or WR is asserted.
See Section “16.6.2. Multiplexed Mode” on page 109 for more information.
A[15:8]
ADDRESS BUS
74HC373
A[15:8]
A[7:0]
ALE
G
E
M
I
AD[7:0]
ADDRESS/DATA BUS
VDD
D
Q
64 K X 8
SRAM
(Optional)
8
I/O[7:0]
F
CE
WE
OE
WR
RD
Figure 16.1. Multiplexed Configuration Example
Rev. 0.2
101
C8051F70x/71x
16.4.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Non-
multiplexed Configuration is shown in Figure 16.2. See Section “16.6.1. Non-Multiplexed Mode” on
page 106 for more information about Non-multiplexed operation.
A[15:0]
ADDRESS BUS
A[15:0]
E
M
I
VDD
(Optional)
64 K X 8
SRAM
I/O[7:0]
8
D[7:0]
DATA BUS
CE
WE
OE
F
WR
RD
Figure 16.2. Non-multiplexed Configuration Example
102
Rev. 0.2
C8051F70x/71x
16.5. Memory Mode Selection
The external data memory space can be configured in one of four modes, shown in Figure 16.3, based on
the EMIF Mode bits in the EMI0CF register (SFR Definition 16.2). These modes are summarized below.
More information about the different modes can be found in Section “16.6. Timing” on page 104.
EMI0CF[3:2] = 00
EMI0CF[3:2] = 01
EMI0CF[3:2] = 10
EMI0CF[3:2] = 11
0xFFFF
0xFFFF
0xFFFF
0xFFFF
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
Off-Chip
Memory
(No Bank Select)
Off-Chip
Memory
(Bank Select)
Off-Chip
Memory
On-Chip XRAM
On-Chip XRAM
0x0000
0x0000
0x0000
0x0000
Figure 16.3. EMIF Operating Modes
16.5.1. Internal XRAM Only
When bits EMI0CF[3:2] are set to 00, all MOVX instructions will target the internal XRAM space on the
device. Memory accesses to addresses beyond the populated space will wrap on 4 kB boundaries. As an
example, the addresses 0x1000 and 0x2000 both evaluate to address 0x0000 in on-chip XRAM space.
8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address
and R0 or R1 to determine the low-byte of the effective address.
16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
16.5.2. Split Mode without Bank Select
When bit EMI0CF.[3:2] are set to 01, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
Effective addresses above the internal XRAM size boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the
upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate
the upper address bits at will by setting the Port state directly via the port latches. This behavior is in
contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus A[7:0]
are driven, determined by R0 or R1.
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip
or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are driven
during the off-chip transaction.
Rev. 0.2
103
C8051F70x/71x
16.5.3. Split Mode with Bank Select
When EMI0CF[3:2] are set to 10, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
Effective addresses above the internal XRAM size boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the lower
8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus A[15:0] are
driven in “Bank Select” mode.
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip
or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
16.5.4. External Only
When EMI0CF[3:2] are set to 11, all MOVX operations are directed to off-chip space. On-chip XRAM is not
visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the
internal XRAM size boundary.
8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven
(identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This
allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower
8-bits of the effective address A[7:0] are determined by the contents of R0 or R1.
16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full
16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
16.6. Timing
The timing parameters of the External Memory Interface can be configured to enable connection to
devices having different setup and hold time requirements. The Address Setup time, Address Hold time,
RD and WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in
units of SYSCLK periods through EMI0TC, shown in SFR Definition 16.3, and EMI0CF[1:0].
The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing
parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution
time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for RD or WR pulse + 4 SYSCLKs).
For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYS-
CLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed mode is
7 SYSCLK cycles (2 for /ALE + 1 for RD or WR + 4). The programmable setup and hold times default to
the maximum delay settings after a reset. Table 16.1 lists the ac parameters for the External Memory Inter-
face, and Figure 16.4 through Figure 16.9 show the timing diagrams for the different External Memory
Interface modes and MOVX operations.
104
Rev. 0.2
C8051F70x/71x
SFR Definition 16.3. EMI0TC: External Memory Timing Control
Bit
7
6
5
4
3
2
1
0
EAS[1:0]
R/W
EWR[3:0]
R/W
EAH[1:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xEE; SFR Page = F
Bit
Name
Function
7:6
EAS[1:0] EMIF Address Setup Time Bits.
00: Address setup time = 0 SYSCLK cycles.
01: Address setup time = 1 SYSCLK cycle.
10: Address setup time = 2 SYSCLK cycles.
11: Address setup time = 3 SYSCLK cycles.
5:2 EWR[3:0] EMIF WR and RD Pulse-Width Control Bits.
0000: WR and RD pulse width = 1 SYSCLK cycle.
0001: WR and RD pulse width = 2 SYSCLK cycles.
0010: WR and RD pulse width = 3 SYSCLK cycles.
0011: WR and RD pulse width = 4 SYSCLK cycles.
0100: WR and RD pulse width = 5 SYSCLK cycles.
0101: WR and RD pulse width = 6 SYSCLK cycles.
0110: WR and RD pulse width = 7 SYSCLK cycles.
0111: WR and RD pulse width = 8 SYSCLK cycles.
1000: WR and RD pulse width = 9 SYSCLK cycles.
1001: WR and RD pulse width = 10 SYSCLK cycles.
1010: WR and RD pulse width = 11 SYSCLK cycles.
1011: WR and RD pulse width = 12 SYSCLK cycles.
1100: WR and RD pulse width = 13 SYSCLK cycles.
1101: WR and RD pulse width = 14 SYSCLK cycles.
1110: WR and RD pulse width = 15 SYSCLK cycles.
1111: WR and RD pulse width = 16 SYSCLK cycles.
1:0
EAH[1:0] EMIF Address Hold Time Bits.
00: Address hold time = 0 SYSCLK cycles.
01: Address hold time = 1 SYSCLK cycle.
10: Address hold time = 2 SYSCLK cycles.
11: Address hold time = 3 SYSCLK cycles.
Rev. 0.2
105
C8051F70x/71x
16.6.1. Non-Multiplexed Mode
16.6.1.1. 16-bit MOVX: EMI0CF[4:2] = 101, 110, or 111
Nonmuxed 16-bit WRITE
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPL
EMIF WRITE DATA
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
WR
RD
Nonmuxed 16-bit READ
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPL
EMIF READ DATA
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
RD
WR
Figure 16.4. Non-multiplexed 16-bit MOVX Timing
106
Rev. 0.2
C8051F70x/71x
16.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 101 or 111
Nonmuxed 8-bit WRITE without Bank Select
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF WRITE DATA
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
WR
RD
Nonmuxed 8-bit READ without Bank Select
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF READ DATA
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
RD
WR
Figure 16.5. Non-multiplexed 8-bit MOVX without Bank Select Timing
Rev. 0.2
107
C8051F70x/71x
16.6.1.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 110
Nonmuxed 8-bit WRITE with Bank Select
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF WRITE DATA
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
WR
RD
Nonmuxed 8-bit READ with Bank Select
EMIF ADDRESS (8 MSBs) from EMI0CN
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF READ DATA
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
RD
WR
Figure 16.6. Non-multiplexed 8-bit MOVX with Bank Select Timing
108
Rev. 0.2
C8051F70x/71x
16.6.2. Multiplexed Mode
16.6.2.1. 16-bit MOVX: EMI0CF[4:2] = 001, 010, or 011
Muxed 16-bit WRITE
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
EMIF WRITE DATA
T
T
ALEL
ALEH
ALE
T
T
WDH
WDS
T
T
T
ACH
ACS
ACW
WR
RD
Muxed 16-bit READ
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
EMIF READ DATA
T
T
ALEL
ALEH
T
T
RDH
RDS
ALE
T
T
T
ACH
ACS
ACW
RD
WR
Figure 16.7. Multiplexed 16-bit MOVX Timing
Rev. 0.2
109
C8051F70x/71x
16.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 001 or 011
Muxed 8-bit WRITE Without Bank Select
ADDR[15:8]
EMIF ADDRESS (8 LSBs) from
AD[7:0]
EMIF WRITE DATA
R0 or R1
T
T
ALEL
ALEH
ALE
T
T
WDH
WDS
T
T
T
ACH
ACS
ACW
WR
RD
Muxed 8-bit READ Without Bank Select
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 LSBs) from
R0 or R1
EMIF READ DATA
T
T
ALEL
ALEH
T
T
RDH
RDS
ALE
T
T
T
ACH
ACS
ACW
RD
l
WR
Figure 16.8. Multiplexed 8-bit MOVX without Bank Select Timing
110
Rev. 0.2
C8051F70x/71x
16.6.2.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 010
Muxed 8-bit WRITE with Bank Select
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
EMIF WRITE DATA
T
T
ALEL
ALEH
ALE
T
T
WDH
WDS
T
T
T
ACH
ACS
ACW
WR
RD
Muxed 8-bit READ with Bank Select
EMIF ADDRESS (8 MSBs) from EMI0CN
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 LSBs) from
R0 or R1
EMIF READ DATA
T
T
ALEL
ALEH
T
T
RDH
RDS
ALE
T
T
T
ACH
ACS
ACW
RD
WR
Figure 16.9. Multiplexed 8-bit MOVX with Bank Select Timing
Rev. 0.2
111
C8051F70x/71x
Table 16.1. AC Parameters for External Memory Interface
Parameter
Description
Min*
Max*
3 x T
Units
Address/Control Setup Time
0
ns
T
SYSCLK
ACS
Address/Control Pulse Width
Address/Control Hold Time
Address Latch Enable High Time
Address Latch Enable Low Time
Write Data Setup Time
T
16 x T
3 x T
ns
ns
ns
ns
ns
ns
ns
ns
T
SYSCLK
SYSCLK
ACW
0
T
SYSCLK
SYSCLK
SYSCLK
ACH
T
T
T
4 x T
4 x T
T
SYSCLK
SYSCLK
ALEH
T
ALEL
19 x T
T
SYSCLK
SYSCLK
WDS
Write Data Hold Time
0
3 x T
T
SYSCLK
WDH
Read Data Setup Time
20
0
—
T
T
RDS
Read Data Hold Time
—
RDH
Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
112
Rev. 0.2
C8051F70x/71x
Table 16.2. EMIF Pinout (C8051F70x/71x)
Multiplexed Mode
Non Multiplexed Mode
Signal Name
RD
Port Pin
P6.1
P6.0
P6.2
P5.0
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
—
Signal Name
RD
WR
D0
Port Pin
P6.1
P6.0
P5.0
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
WR
ALE
D0/A0
D1/A1
D2/A2
D3/A3
D4/A4
D5/A5
D6/A6
D7/A7
A8
D1
D2
D3
D4
D5
D6
D7
A0
A1
A9
A2
A10
A3
A11
A4
A12
A5
A13
A6
A14
A7
A15
A8
—
A9
—
—
A10
A11
A12
A13
A14
A15
—
—
—
—
—
—
—
—
—
—
Rev. 0.2
113
C8051F70x/71x
17. In-System Device Identification
The C8051F70x/71x has SFRs that identify the device family and derivative. These SFRs can be read by
firmware at runtime to determine the capabilities of the MCU that is executing code. This allows the same
firmware image to run on MCUs with different memory sizes and peripherals, and dynamically changing
functionality to suit the capabilities of that MCU.
In order for firmware to identify the MCU, it must read three SFRs. HWID describes the MCU’s family,
DERIVID describes the specific derivative within that device family, and REVID describes the hardware
revision of the MCU.
SFR Definition 17.1. HWID: Hardware Identification Byte
Bit
7
6
5
4
3
2
1
0
HWID[7:0]
Name
Type
Reset
R
1
R
1
R
1
R
0
R
0
R
0
R
0
R
1
SFR Address = 0xC4; SFR Page = F
Bit
Name
Description
7:0
HWID[7:0]
Hardware Identification byte
Describes the MCU family.
0xE1: Devices covered in this document (C8051F70x/71x)
SFR Definition 17.2. DERIVID: Derivative Identification Byte
Bit
7
6
5
4
3
2
1
0
DERIVID[7:0]
Name
Type
Reset
R
R
R
R
R
R
R
R
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0xEC; SFR Page = F
Bit
Name
DERIVID[7:0] Derivative Identification byte
Shows the C8051F70x/71x derivative being used.
Description
7:0
0xD0: C8051F700; 0xD1: C8051F701; 0xD2: C8051F702; 0xD3: C8051F703
0xD4: C8051F704; 0xD5: C8051F705; 0xD6: C8051F706; 0xD7: C8051F707
0xD8: C8051F708; 0xD9: C8051F709; 0xDA: C8051F710; 0xDB: C8051F711
0xDC: C8051F712; 0xDD: C8051F713; 0xDE: C8051F714; 0xDF: C8051F715
114
Rev. 0.2
C8051F70x/71x
SFR Definition 17.3. REVID: Hardware Revision Identification Byte
Bit
7
6
5
4
3
2
1
0
REVID[7:0]
Name
Type
Reset
R
R
R
R
R
R
R
R
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0xAD; SFR Page = F
Bit Name
7:0 REVID[7:0]
Description
Hardware Revision Identification byte
Shows the C8051F70x/71x hardware revision being used.
For example, 0x00 = Revision A.
Rev. 0.2
115
C8051F70x/71x
18. 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 C8051F70x/71x's resources and peripher-
als. The CIP-51 controller core 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
C8051F70x/71x. This allows the addition of new functionality while retaining compatibility with the MCS-
51™ instruction set. Table 18.1 lists the SFRs implemented in the C8051F70x/71x device family.
The SFR registers are accessed anytime the direct addressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are bit-
addressable 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 data sheet, as indicated in
Table 18.2, for a detailed description of each register.
116
Rev. 0.2
C8051F70x/71x
Table 18.1. Special Function Register (SFR) Memory Map
SFR
Page
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
Addr
0
F
PCA0L
P0DRV
PCA0H PCA0CPL0 PCA0CPH0
SPI0CN
B
VDM0CN
F8
F0
E8
E0
D8
D0
C8
C0
B8
B0
A8
A0
98
90
88
80
P1DRV
P2DRV
P3DRV
P4DRV
P4MDIN
PCA0MD
P5DRV
0
F
P0MAT
P2MDIN
P0MASK
P3MDIN
P0MDIN
P1MDIN
P5MDIN
0
F
PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2
DERIVID
ADC0CN
ACC
RSTSRC
EIE2
EMI0TC
0
F
P1MAT
XBR0
P1MASK
XBR1
WDTCN
EIE1
IT01CF
0
F
PCA0CN
PSW
TMR2CN
SMB0CN
IP
CRC0DATA PCA0CPM0 PCA0CPM1 PCA0CPM2
0
F
EEDATA
REF0CN
P0SKIP
TMR2L
P1SKIP
TMR2H
P2SKIP
EIP1
0
F
TMR2RLL TMR2RLH
EIP2
0
F
SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH
P6DRV
HWID
EECNTL
EEKEY
EMI0CF
0
F
ADC0MX
REG0CN SMB0ADR SMB0ADM ADC0CF
ADC0L
CLKSEL
ADC0H
OSCICL
0
F
P3
P6
P5
EEADDR
FLKEY
OSCXCN
REVID
0
F
CS0DL
OSCICN
CS0DH
EMI0CN
IE
P4
P3MDOUT
SFRPAGE
CPT0MX
0
F
SPI0CFG
PCA0PWM SPI0CKR
SPI0DAT
CPT0CN
P2
P0MDOUT P1MDOUT P2MDOUT
0
F
CS0CN
CS0MX
CPT0MD
CS0CF
SCON0
P1
SBUF0
P4MDOUT P5MDOUT P6MDOUT
0
F
TMR3CN TMR3RLL TMR3RLH
CRC0CN
TMR3L
TMR3H
CS0THL
CS0THH
CS0SS
CS0SE
CRC0IN CRC0FLIP CRC0AUTO CRC0CNT
0
F
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
PSCTL
0
F
P0
SP
DPL
DPH
PCON
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
Notes:
1. SFR addresses ending in 0x0 or 0x8 (leftmost column) are bit-addressable.
2. SFRs indicated with bold lettering and shaded cells are available on both SFR Page 0 and F.
Rev. 0.2
117
C8051F70x/71x
SFR Definition 18.1. SFRPAGE: SFR Page
Bit
7
6
5
4
3
2
1
0
SFRPAGE[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA7; SFR Page = All Pages
Bit Name
7:0 SFRPAGE[7:0] SFR Page Bits.
Description
Represents the SFR Page the C8051 core uses when reading or modifying SFRs.
Write: Sets the SFR Page.
Read: Byte is the SFR page the C8051 core is using.
Table 18.2. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
ACC
Address
Page
Description
Page
0xE0
All Pages Accumulator
91
0xBC
0xE8
0xC4
0xC3
0xBE
0xBD
0xC6
0xC5
0xBB
0xF0
0x8E
0xBD
0x9B
0x9D
0x9F
0x96
0x91
0x97
F
ADC0 Configuration
51
53
ADC0CF
ADC0CN
ADC0GTH
ADC0GTL
ADC0H
All Pages ADC0 Control
0
0
0
0
0
0
0
ADC0 Greater-Than Compare High
ADC0 Greater-Than Compare Low
ADC0 High
54
54
52
ADC0 Low
52
ADC0L
ADC0 Less-Than Compare Word High
ADC0 Less-Than Compare Word Low
AMUX0 Multiplexer Channel Select
55
ADC0LTH
ADC0LTL
ADC0MX
B
55
58
All Pages B Register
92
All Pages Clock Control
246
246
69
CKCON
F
0
0
0
F
F
F
Clock Select
CLKSEL
CPT0CN
CPT0MD
CPT0MX
CRC0AUTO
CRC0CN
CRC0CNT
Comparator0 Control
Comparator0 Mode Selection
Comparator0 MUX Selection
CRC0 Automatic Control Register
CRC0 Control
70
72
200
198
200
CRC0 Automatic Flash Sector Count
118
Rev. 0.2
C8051F70x/71x
Table 18.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
CRC0DATA
CRC0FLIP
CRC0IN
CS0THH
CS0THL
CS0CN
CS0DH
CS0DL
CS0CF
CS0MX
CS0SE
CS0SS
DERIVID
DPH
Address
Page
Description
Page
0xD9
F
F
F
0
0
0
0
0
0
0
F
F
F
CRC0 Data Output
CRC0 Bit Flip
199
0x95
0x94
0x97
0x96
0x9A
0xAA
0xA9
0x9E
0x9C
0x93
0x92
0xEC
0x83
0x82
0xB6
0xC5
0xD1
0xC6
0xE6
0xE7
0xCE
0xCF
0xC7
0xAA
0xEE
0xB7
0xC4
0xA8
0xB8
0xE4
0xBF
0xA9
0xB5
201
199
81
CRC Data Input
CS0 Digital Compare Threshold High
CS0 Digital Compare Threshold High
CS0 Control
81
77
CS0 Data High
79
CS0 Data Low
79
CS0 Configuration
78
CS0 Mux
83
Auto Scan End Channel
Auto Scan Start Channel
Derivative Identification
80
80
114
90
All Pages Data Pointer High
All Pages Data Pointer Low
All Pages EEPROM Byte Address
90
DPL
142
144
143
145
128
129
130
131
100
99
EEADDR
EECNTL
EEDATA
EEKEY
EIE1
F
EEPROM Control
All Pages EEPROM Byte Data
EEPROM Protect Key
F
All Pages Extended Interrupt Enable 1
All Pages Extended Interrupt Enable 2
EIE2
F
F
F
F
F
Extended Interrupt Priority 1
Extended Interrupt Priority 2
EMIF Configuration
EIP1
EIP2
EMI0CF
EMI0CN
EMI0TC
FLKEY
HWID
EMIF Control
EMIF Timing Control
105
140
114
126
127
133
159
160
162
All Pages Flash Lock And Key
Hardware Identification
F
All Pages Interrupt Enable
All Pages Interrupt Priority
IE
IP
F
F
F
F
INT0/INT1 Configuration
IT01CF
OSCICL
OSCICN
OSCXCN
Internal Oscillator Calibration
Internal Oscillator Control
External Oscillator Control
Rev. 0.2
119
C8051F70x/71x
Table 18.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
Address
Page
Description
Page
0x80
All Pages Port 0 Latch
179
P0
0xF9
0xF4
0xF3
0xF1
0xA4
0xD4
0x90
0xFA
0xE2
0xE1
0xF2
0xA5
0xD5
0xA0
0xFB
0xF3
0xA6
0xD6
0xB0
0xFC
0xF4
0xAF
0xAC
0xFD
0xF5
0x9A
0xB3
0xFE
0xF6
0x9B
0xB2
0xC1
0x9C
F
0
0
F
F
F
Port 0 Drive Strength
181
176
177
179
180
180
181
183
177
178
182
182
183
184
186
184
185
185
186
188
187
187
188
190
189
189
190
192
191
191
192
193
193
P0DRV
P0MASK
P0MAT
P0MDIN
P0MDOUT
P0SKIP
P1
Port 0 Mask
Port 0 Match
Port 0 Input Mode Configuration
Port 0 Output Mode Configuration
Port 0 Skip
All Pages Port 1 Latch
F
0
0
F
F
F
Port 1 Drive Strength
P1DRV
P1MASK
P1MAT
P1MDIN
P1MDOUT
P1SKIP
P2
P0 Mask
P1 Match
Port 1 Input Mode Configuration
Port 1 Output Mode Configuration
Port 1 Skip
All Pages Port 2 Latch
F
F
F
F
Port 2 Drive Strength
P2DRV
P2MDIN
P2MDOUT
P2SKIP
P3
Port 2 Input Mode Configuration
Port 2 Output Mode Configuration
Port 2 Skip
All Pages Port 3 Latch
F
F
F
Port 3 Drive Strength
P3DRV
P3MDIN
P3MDOUT
P4
Port 3 Input Mode Configuration
Port 3 Output Mode Configuration
All Pages Port 4 Latch
F
F
F
Port 4 Drive Strength
P4DRV
P4MDIN
P4MDOUT
P5
Port 4 Input Mode Configuration
Port 4 Output Mode Configuration
All Pages Port 5 Latch
F
F
F
Port 5 Drive Strength
P5DRV
P5MDIN
P5MDOUT
P6
Port 5 Input Mode Configuration
Port 5 Output Mode Configuration
All Pages Port 6 Latch
F
F
Port 6 Drive Strength
P6DRV
P6MDOUT
Port 6 Output Mode Configuration
120
Rev. 0.2
C8051F70x/71x
Table 18.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
PCA0CN
Address
Page
Description
Page
0xD8
All Pages PCA Control
279
0xFC
0xEA
0xEC
0xFB
0xE9
0xEB
0xDA
0xDB
0xDC
0xFA
0xF9
0xED
0xA1
0x87
0x8F
0xD0
0xD2
0xB9
0xAD
0xEF
0x99
0x98
0xA7
0xBB
0xBA
0xC1
0xC0
0xC2
0x81
0xA1
0xA2
0xF8
0xA3
0
0
0
0
0
0
F
F
F
0
0
F
F
PCA Capture 0 High
PCA Capture 1 High
284
284
284
284
284
284
282
282
282
283
283
280
281
148
139
93
PCA0CPH0
PCA0CPH1
PCA0CPH2
PCA0CPL0
PCA0CPL1
PCA0CPL2
PCA0CPM0
PCA0CPM1
PCA0CPM2
PCA0H
PCA Capture 2 High
PCA Capture 0 Low
PCA Capture 1 Low
PCA Capture 2 Low
PCA Module 0 Mode Register
PCA Module 1 Mode Register
PCA Module 2 Mode Register
PCA Counter High
PCA Counter Low
PCA0L
PCA Mode
PCA0MD
PCA0PWM
PCON
PCA PWM Configuration
All Pages Power Control
All Pages Program Store R/W Control
All Pages Program Status Word
PSCTL
PSW
F
F
F
Voltage Reference Control
Voltage Regulator Control
Revision ID
63
REF0CN
REG0CN
REVID
65
115
154
243
242
118
213
212
208
210
214
91
All Pages Reset Source Configuration/Status
All Pages UART0 Data Buffer
All Pages UART0 Control
RSTSRC
SBUF0
SCON0
All Pages SFR Page
SFRPAGE
SMB0ADM
SMB0ADR
SMB0CF
SMB0CN
SMB0DAT
SP
F
F
0
SMBus Slave Address mask
SMBus Slave Address
SMBus Configuration
All Pages SMBus Control
SMBus Data
All Pages Stack Pointer
0
0
F
SPI0 Configuration
SPI0 Clock Rate Control
231
233
232
233
SPI0CFG
SPI0CKR
SPI0CN
All Pages SPI0 Control
SPI0 Data
0
SPI0DAT
Rev. 0.2
121
C8051F70x/71x
Table 18.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
TCON
Address
Page
Description
Page
0x88
All Pages Timer/Counter Control
All Pages Timer/Counter 0 High
All Pages Timer/Counter 1 High
All Pages Timer/Counter 0 Low
All Pages Timer/Counter 1 Low
All Pages Timer/Counter Mode
All Pages Timer/Counter 2 Control
251
0x8C
0x8D
0x8A
0x8B
0x89
0xC8
0xCD
0xCC
0xCB
0xCA
0x91
0x95
0x94
0x93
0x92
0xFF
0xE3
0xE1
0xE2
254
254
253
253
252
258
260
260
259
259
264
266
266
265
265
152
156
174
175
TH0
TH1
TL0
TL1
TMOD
TMR2CN
TMR2H
TMR2L
TMR2RLH
TMR2RLL
TMR3CN
TMR3H
TMR3L
TMR3RLH
TMR3RLL
VDM0CN
WDTCN
XBR0
0
0
0
0
0
0
0
0
0
Timer/Counter 2 High
Timer/Counter 2 Low
Timer/Counter 2 Reload High
Timer/Counter 2 Reload Low
Timer/Counter 3 Control
Timer/Counter 3 High
Timer/Counter 3 Low
Timer/Counter 3 Reload High
Timer/Counter 3 Reload Low
All Pages VDD Monitor Control
All Pages Watchdog Timer Control
F
F
Port I/O Crossbar Control 0
Port I/O Crossbar Control 1
Reserved
XBR1
All other SFR Locations
122
Rev. 0.2
C8051F70x/71x
19. Interrupts
The C8051F70x/71x includes an extended interrupt system supporting a total of 16 interrupt sources with
two priority levels. The allocation of interrupt sources between on-chip peripherals and external input 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 prede-
termined 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 regard-
less of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE–EIE1). However, interrupts must first be globally enabled by setting the EA bit
(IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables
all interrupt sources regardless of the individual interrupt-enable settings.
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.
Rev. 0.2
123
C8051F70x/71x
19.1. MCU Interrupt Sources and Vectors
The C8051F70x/71x MCUs support 12 interrupt sources. Software can simulate an interrupt by setting an
interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated
and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt
sources, associated vector addresses, priority order and control bits are summarized in Table 19.1. 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).
19.1.1. Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low prior-
ity interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure
its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 19.1.
19.1.2. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5
system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no
other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
124
Rev. 0.2
C8051F70x/71x
Table 19.1. Interrupt Summary
Interrupt Source
Interrupt Priority Pending Flag
Enable
Flag
Priority
Control
Vector
Order
Reset
0x0000
0x0003
Top
0
None
N/A N/A Always
Enabled
Always
Highest
External Interrupt 0
(INT0)
IE0 (TCON.1)
Y
Y
EX0 (IE.0) PX0 (IP.0)
Timer 0 Overflow
External Interrupt 1
(INT1)
0x000B
0x0013
1
2
TF0 (TCON.5)
IE1 (TCON.3)
Y
Y
Y
Y
ET0 (IE.1) PT0 (IP.1)
EX1 (IE.2) PX1 (IP.2)
Timer 1 Overflow
UART0
0x001B
0x0023
3
4
TF1 (TCON.7)
RI0 (SCON0.0)
Y
Y
Y
N
ET1 (IE.3) PT1 (IP.3)
ES0 (IE.4) PS0 (IP.4)
TI0 (SCON0.1)
Timer 2 Overflow
SPI0
0x002B
0x0033
5
6
TF2H (TMR2CN.7)
TF2L (TMR2CN.6)
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
SI (SMB0CN.0)
Y
Y
N
ET2 (IE.5) PT2 (IP.5)
ESPI0
(IE.6)
PSPI0
(IP.6)
SMB0
0x003B
0x0043
0x0043
7
8
9
Y
N
ESMB0
(EIE1.0)
PSMB0
(EIP1.0)
PMAT
Port Match
None
N/A N/A EMAT
(EIE1.1)
(EIP1.1)
EWADC0 PWADC0
ADC0
Window Compare
ADC0
Conversion Complete
Programmable
Counter Array
Comparator0
AD0WINT (ADC0CN.3) Y
N
N
N
N
(EIE1.2)
(EIP1.2)
0x004B 10
0x0053 11
0x005B 12
AD0INT (ADC0CN.5)
Y
Y
N
EADC0
(EIE1.3)
PADC0
(EIP1.3)
CF (PCA0CN.7)
EPCA0
PPCA0
(EIE1.4)
(EIP1.4)
CCFn (PCA0CN.n)
CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5)
ECP0
PCP0
(EIE1.5)
(EIP1.5)
RESERVED
Timer 3 Overflow
0x0073
14
TF3H (TMR3CN.7)
TF3L (TMR3CN.6)
CS0INT (CS0CN.5)
N
N
N
N
N
N
ET3
(EIE1.7)
PT3
(EIP1.7)
CS0 Conversion Com- 0x007B 15
plete
CS0 Greater Than
ECSCPT PSCCPT
(EIE2.0) (EIP2.0)
ECSGRT PSCGRT
(EIE2.1) (EIP2.1)
0x0083
16
CS0CMPF (CS0CN.0)
19.2. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described in this section.
Refer to the data sheet section associated with a particular on-chip peripheral for information regarding
valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
Rev. 0.2
125
C8051F70x/71x
SFR Definition 19.1. IE: Interrupt Enable
Bit
7
6
5
4
3
2
1
0
EA
ESPI0
ET2
ES0
ET1
EX1
ET0
EX0
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xA8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
EA
Enable All Interrupts.
Globally enables/disables all interrupts. It overrides individual interrupt mask settings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
6
5
4
3
2
1
0
ESPI0 Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrupts.
1: Enable interrupt requests generated by SPI0.
ET2
ES0
ET1
EX1
ET0
EX0
Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt requests generated by the TF2L or TF2H flags.
Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable external interrupt 1.
1: Enable interrupt requests generated by the INT1 input.
Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable external interrupt 0.
1: Enable interrupt requests generated by the INT0 input.
126
Rev. 0.2
C8051F70x/71x
SFR Definition 19.2. IP: Interrupt Priority
Bit
7
6
5
4
3
2
1
0
PSPI0
PT2
PS0
PT1
PX1
PT0
PX0
Name
Type
Reset
R
1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xB8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
Unused Unused. Read = 1b, Write = Don't Care.
6
PSPI0
PT2
PS0
PT1
PX1
PT0
PX0
Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
5
4
3
2
1
0
Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority level.
1: Timer 2 interrupt set to high priority level.
UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority level.
1: UART0 interrupt set to high priority level.
Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority level.
1: Timer 1 interrupt set to high priority level.
External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
Rev. 0.2
127
C8051F70x/71x
SFR Definition 19.3. EIE1: Extended Interrupt Enable 1
Bit
7
6
5
4
3
2
1
0
ET3
Reserved
ECP0
EADC0
EPCA0
EWADC0
EMAT
ESMB0
Name
Type
Reset
R/W
0
W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xE6; SFR Page = All Pages
Bit
Name
Function
7
ET3
Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupt.
1: Enable interrupt requests generated by the TF3L or TF3H flags.
Unused Reserved. Must write 0.
ECP0 Enable Comparator0 (CP0) Interrupt.
6
5
This bit sets the masking of the CP0 rising edge or falling edge interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF and CP0FIF flags.
4
3
2
1
0
EADC0 Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
EPCA0 Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
EWADC0 Enable Window Comparison ADC0 interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT).
EMAT
Enable Port Match Interrupts.
This bit sets the masking of the Port Match event interrupt.
0: Disable all Port Match interrupts.
1: Enable interrupt requests generated by a Port Match.
ESMB0 Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
128
Rev. 0.2
C8051F70x/71x
SFR Definition 19.4. EIE2: Extended Interrupt Enable 2
Bit
7
6
5
4
3
2
1
0
ECSGRT ECSCPT
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R/W
0
R/W
0
SFR Address = 0xE7; SFR Page = All Pages
Bit
Name
Function
7:2
1
Unused Unused. Read = 000000b; Write = don’t care.
ECSGRT
ECSCPT
Enable Capacitive Sense Greater Than Comparator Interrupt.
0: Disable Capacitive Sense Greater Than Comparator interrupt.
1: Enable interrupt requests generated by CS0CMPF.
0
Enable Capacitive Sense Conversion Complete Interrupt.
0: Disable Capacitive Sense Conversion Complete interrupt.
1: Enable interrupt requests generated by CS0INT.
Rev. 0.2
129
C8051F70x/71x
SFR Definition 19.5. EIP1: Extended Interrupt Priority 1
Bit
7
6
5
4
3
2
1
0
PT3
Reserved
PCP0
PPCA0
PADC0
PWADC0
PMAT
PSMB0
Name
Type
Reset
W/R
0
W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xCE; SFR Page = F
Bit
Name
Function
7
PT3
Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupt set to low priority level.
1: Timer 3 interrupt set to high priority level.
6
5
Unused Reserved. Must write 0.
PCP0 Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 rising edge or falling edge interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
4
3
2
1
0
PPCA0 Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority level.
1: PCA0 interrupt set to high priority level.
PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
PWADC0 ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority level.
1: ADC0 Window interrupt set to high priority level.
PMAT
Port Match Interrupt Priority Control.
This bit sets the priority of the Port Match Event interrupt.
0: Port Match interrupt set to low priority level.
1: Port Match interrupt set to high priority level.
PSMB0 SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
130
Rev. 0.2
C8051F70x/71x
SFR Definition 19.6. EIP2: Extended Interrupt Priority 2
Bit
7
6
5
4
3
2
1
0
Reserved Reserved Reserved Reserved Reserved Reserved PSCGRT PSCCPT
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R/W
0
R/W
0
SFR Address = 0xCF; SFR Page = F
Bit
Name
Function
7:2
1
Unused Reserved.
PSCGRT
Capacitive Sense Greater Than Comparator Priority Control.
This bit sets the priority of the Capacitive Sense Greater Than Comparator interrupt.
0: CS0 Greater Than Comparator interrupt set to low priority level.
1: CS0 Greater Than Comparator set to high priority level.
0
PSCCPT
Capacitive Sense Conversion Complete Priority Control.
This bit sets the priority of the Capacitive Sense Conversion Complete interrupt.
0: CS0 Conversion Complete set to low priority level.
1: CS0 Conversion Complete set to high priority level.
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19.3. INT0 and INT1 External Interrupts
The INT0 and INT1 external interrupt sources are configurable as active high or low, edge or level sensi-
tive. The IN0PL (INT0 Polarity) and IN1PL (INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT1 bits in TCON (Section “31.1. Timer 0 and Timer 1” on page 247) select level or
edge sensitive. The table below lists the possible configurations.
IT0
IN0PL
INT0 Interrupt
IT1
IN1PL
INT1 Interrupt
1
1
0
0
0
1
0
1
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
1
1
0
0
0
1
0
1
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
INT0 and INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 19.7). Note
that INT0 and INT0 Port pin assignments are independent of any Crossbar assignments. INT0 and INT1
will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the
Crossbar. To assign a Port pin only to INT0 and/or INT1, configure the Crossbar to skip the selected pin(s).
This is accomplished by setting the associated bit in register XBR0 (see Section “26.3. Priority Crossbar
Decoder” on page 171 for complete details on configuring the Crossbar).
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the INT0 and INT1 external inter-
rupts, respectively. If an INT0 or INT1 external interrupt is configured as edge-sensitive, the corresponding
interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When
configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined
by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The
external interrupt source must hold the input active until the interrupt request is recognized. It must then
deactivate the interrupt request before execution of the ISR completes or another interrupt request will be
generated.
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SFR Definition 19.7. IT01CF: INT0/INT1 Configuration
Bit
7
6
5
4
3
2
1
0
IN1PL
IN1SL[2:0]
IN0PL
IN0SL[2:0]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
0
0
0
1
SFR Address = 0xE4; SFR Page = F
Bit
Name
Function
7
IN1PL
INT1 Polarity.
0: INT1 input is active low.
1: INT1 input is active high.
6:4 IN1SL[2:0]
INT1 Port Pin Selection Bits.
These bits select which Port pin is assigned to INT1. Note that this pin assignment is
independent of the Crossbar; INT1 will monitor the assigned Port pin without disturb-
ing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar
will not assign the Port pin to a peripheral if it is configured to skip the selected pin.
000: Select P0.0
001: Select P0.1
010: Select P0.2
011: Select P0.3
100: Select P0.4
101: Select P0.5
110: Select P0.6
111: Select P0.7
3
IN0PL
INT0 Polarity.
0: INT0 input is active low.
1: INT0 input is active high.
2:0 IN0SL[2:0]
INT0 Port Pin Selection Bits.
These bits select which Port pin is assigned to INT0. Note that this pin assignment is
independent of the Crossbar; INT0 will monitor the assigned Port pin without disturb-
ing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar
will not assign the Port pin to a peripheral if it is configured to skip the selected pin.
000: Select P0.0
001: Select P0.1
010: Select P0.2
011: Select P0.3
100: Select P0.4
101: Select P0.5
110: Select P0.6
111: Select P0.7
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C8051F70x/71x
20. Flash Memory
On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The
Flash memory can be programmed in-system through the C2 interface or by software using the MOVX
write instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. Flash bytes
would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are
automatically timed by hardware for proper execution; data polling to determine the end of the write/erase
operations is not required. Code execution is stalled during Flash write/erase operations. Refer to
Table 7.6 for complete Flash memory electrical characteristics.
20.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Laboratories or a third party vendor. This is the only means for programming a
non-initialized device. For details on the C2 commands to program Flash memory, see Section “33. C2
Interface” on page 285.
The Flash memory can be programmed by software using the MOVX write instruction with the address and
data byte to be programmed provided as normal operands. Before programming Flash memory using
MOVX, Flash programming operations must be enabled by: (1) setting the PSWE Program Store Write
Enable bit (PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the
Flash key codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared
by software. For detailed guidelines on programming Flash from firmware, please see Section “20.4. Flash
Write and Erase Guidelines” on page 136.
To ensure the integrity of the Flash contents, the on-chip VDD Monitor must be enabled and enabled as a
reset source in any system that includes code that writes and/or erases Flash memory from software. Fur-
thermore, there should be no delay between enabling the V Monitor and enabling the V Monitor as a
DD
DD
reset source. Any attempt to write or erase Flash memory while the V
Monitor is disabled, or not
DD
enabled as a reset source, will cause a Flash Error device reset.
20.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be per-
formed. The FLKEY register is detailed in SFR Definition 20.2.
20.1.2. Flash Erase Procedure
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
1. Save current interrupt state and disable interrupts.
2. Set the PSEE bit (register PSCTL).
3. Set the PSWE bit (register PSCTL).
4. Write the first key code to FLKEY: 0xA5.
5. Write the second key code to FLKEY: 0xF1.
6. Using the MOVX instruction, write a data byte to any location within the 512-byte page to be erased.
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7. Clear the PSWE and PSEE bits.
8. Restore previous interrupt state.
Steps 4–6 must be repeated for each 512-byte page to be erased.
Note: Flash security settings may prevent erasure of some Flash pages, such as the reserved area and the page
containing the lock bytes. For a summary of Flash security settings and restrictions affecting Flash erase
operations, please see Section “20.3. Security Options” on page 135.
20.1.3. Flash Write Procedure
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written.
The recommended procedure for writing a single byte in Flash is as follows:
1. Save current interrupt state and disable interrupts.
2. Ensure that the Flash byte has been erased (has a value of 0xFF).
3. Set the PSWE bit (register PSCTL).
4. Clear the PSEE bit (register PSCTL).
5. Write the first key code to FLKEY: 0xA5.
6. Write the second key code to FLKEY: 0xF1.
7. Using the MOVX instruction, write a single data byte to the desired location within the 512-byte sector.
8. Clear the PSWE bit.
9. Restore previous interrupt state.
Steps 5–7 must be repeated for each byte to be written.
Note: Flash security settings may prevent writes to some areas of Flash, such as the reserved area. For a summary
of Flash security settings and restrictions affecting Flash write operations, please see Section “20.3. Security
Options” on page 135.
20.2. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction.
Note: MOVX read instructions always target XRAM.
20.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to 1 before software can modify the Flash memory; both PSWE and PSEE must be set to 1 before soft-
ware can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (reads, writes, and erases) by unprotected code or the C2 interface. The Flash secu-
Rev. 0.2
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C8051F70x/71x
rity mechanism allows the user to lock all Flash pages, starting at page 0, by writing a non-0xFF value to
the lock byte. Note that writing a non-0xFF value to the lock byte will lock all pages of FLASH from
reads, writes, and erases, including the page containing the lock byte.
The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executing on locked pages. Table 20.1 summarizes the Flash security
features of the C8051F70x/71x devices.
Table 20.1. Flash Security Summary
Action
C2 Debug
Interface
User Firmware executing from:
an unlocked page a locked page
Read, Write or Erase unlocked pages
(except page with Lock Byte)
Permitted
Permitted
Permitted
Permitted
Permitted
Permitted
Permitted
Permitted
FEDR
Read, Write or Erase locked pages
(except page with Lock Byte)
Not Permitted FEDR
Read or Write page containing Lock Byte
(if no pages are locked)
Permitted
Permitted
Read or Write page containing Lock Byte
(if any page is locked)
Not Permitted FEDR
Read contents of Lock Byte
(if no pages are locked)
Permitted
Permitted
Read contents of Lock Byte
(if any page is locked)
Not Permitted FEDR
Erase page containing Lock Byte
(if no pages are locked)
Permitted
FEDR
ErasepagecontainingLockByte-Unlockallpages Only by C2DE FEDR
(if any page is locked)
FEDR
Lock additional pages
(change '1's to '0's in the Lock Byte)
Not Permitted FEDR
Not Permitted FEDR
Not Permitted FEDR
FEDR
Unlock individual pages
(change '0's to '1's in the Lock Byte)
FEDR
Read, Write or Erase Reserved Area
FEDR
C2DE - C2 Device Erase (Erases all Flash pages including the page containing the Lock Byte)
FEDR - Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after reset)
- All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset).
- Locking any Flash page also locks the page containing the Lock Byte.
- Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase.
- If user code writes to the Lock Byte, the Lock does not take effect until the next device reset.
20.4. Flash Write and Erase Guidelines
Any system which contains routines which write or erase Flash memory from software involves some risk
that the write or erase routines will execute unintentionally if the CPU is operating outside its specified
operating range of VDD, system clock frequency, or temperature. This accidental execution of Flash modi-
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fying code can result in alteration of Flash memory contents causing a system failure that is only recover-
able by re-Flashing the code in the device.
To help prevent the accidental modification of Flash by firmware, the VDD Monitor must be enabled and
enabled as a reset source on C8051F70x/71x devices for the Flash to be successfully modified. If either
the VDD Monitor or the VDD Monitor reset source is not enabled, a Flash Error Device Reset will be
generated when the firmware attempts to modify the Flash.
The following guidelines are recommended for any system that contains routines which write or erase
Flash from code.
20.4.1. VDD Maintenance and the VDD Monitor
1. If the system power supply is subject to voltage or current "spikes," add sufficient transient protection
devices to the power supply to ensure that the supply voltages listed in the Absolute Maximum Ratings
table are not exceeded.
2. Make certain that the minimum VDD rise time specification of 1 ms is met. If the system cannot meet
this rise time specification, then add an external VDD brownout circuit to the /RST pin of the device that
holds the device in reset until VDD reaches the minimum device operating voltage and re-asserts /RST
if VDD drops below the minimum device operating voltage.
3. Keep the on-chip VDD Monitor enabled and enable the VDD Monitor as a reset source as early in code
as possible. This should be the first set of instructions executed after the Reset Vector. For C-based
systems, this will involve modifying the startup code added by the C compiler. See your compiler
documentation for more details. Make certain that there are no delays in software between enabling the
VDD Monitor and enabling the VDD Monitor as a reset source. Code examples showing this can be
found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site.
Note: On C8051F70x/71x devices, both the VDD Monitor and the VDD Monitor reset source must be enabled to write
or erase Flash without generating a Flash Error Device Reset.
On C8051F70x/71x devices, both the VDD Monitor and the VDD Monitor reset source are enabled by hardware
after a power-on reset.
4. As an added precaution, explicitly enable the VDD Monitor and enable the VDD Monitor as a reset
source inside the functions that write and erase Flash memory. The VDD Monitor enable instructions
should be placed just after the instruction to set PSWE to a 1, but before the Flash write or erase
operation instruction.
5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment operators
and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC =
0x02" is correct, but "RSTSRC |= 0x02" is incorrect.
6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a 1. Areas to check
are initialization code which enables other reset sources, such as the Missing Clock Detector or
Comparator, for example, and instructions which force a Software Reset. A global search on "RSTSRC"
can quickly verify this.
20.4.2. PSWE Maintenance
7. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a 1. There should be
exactly one routine in code that sets PSWE to a 1 to write Flash bytes and one routine in code that sets
both PSWE and PSEE both to a 1 to erase Flash pages.
8. Minimize the number of variable accesses while PSWE is set to a 1. Handle pointer address updates
and loop maintenance outside the "PSWE = 1;... PSWE = 0;" area. Code examples showing this can be
found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site.
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C8051F70x/71x
9. Disable interrupts prior to setting PSWE to a 1 and leave them disabled until after PSWE has been
reset to 0. Any interrupts posted during the Flash write or erase operation will be serviced in priority
order after the Flash operation has been completed and interrupts have been re-enabled by software.
10.Make certain that the Flash write and erase pointer variables are not located in XRAM. See your
compiler documentation for instructions regarding how to explicitly locate variables in different memory
areas.
11.Add address bounds checking to the routines that write or erase Flash memory to ensure that a routine
called with an illegal address does not result in modification of the Flash.
20.4.3. System Clock
12.If operating from an external crystal, be advised that crystal performance is susceptible to electrical
interference and is sensitive to layout and to changes in temperature. If the system is operating in an
electrically noisy environment, use the internal oscillator or use an external CMOS clock.
13.If operating from the external oscillator, switch to the internal oscillator during Flash write or erase
operations. The external oscillator can continue to run, and the CPU can switch back to the external
oscillator after the Flash operation has completed.
Additional Flash recommendations and example code can be found in AN201, "Writing to Flash from Firm-
ware", available from the Silicon Laboratories web site.
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SFR Definition 20.1. PSCTL: Program Store R/W Control
Bit
7
6
5
4
3
2
1
0
PSEE
PSWE
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R/W
0
R/W
0
SFR Address =0x8F; SFR Page = All Pages
Bit
Name
Function
7:2
Unused Unused.
Read = 000000b, Write = don’t care.
1
PSEE
Program Store Erase Enable.
Setting this bit (in combination with PSWE) allows an entire page of Flash program
memory to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic
1), a write to Flash memory using the MOVX instruction will erase the entire page that
contains the location addressed by the MOVX instruction. The value of the data byte
written does not matter.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
0
PSWE Program Store Write Enable.
Setting this bit allows writing a byte of data to the Flash program memory using the
MOVX write instruction. The Flash location should be erased before writing data.
0: Writes to Flash program memory disabled.
1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash
memory.
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SFR Definition 20.2. FLKEY: Flash Lock and Key
Bit
7
6
5
4
3
2
1
0
FLKEY[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xB7; SFR Page = All Pages
Bit Name
Function
7:0 FLKEY[7:0] Flash Lock and Key Register.
Write:
This register provides a lock and key function for Flash erasures and writes. Flash
writes and erases are enabled by writing 0xA5 followed by 0xF1 to the FLKEY regis-
ter. Flash writes and erases are automatically disabled after the next write or erase is
complete. If any writes to FLKEY are performed incorrectly, or if a Flash write or erase
operation is attempted while these operations are disabled, the Flash will be perma-
nently
locked from writes or erasures until the next device reset. If an application never
writes to Flash, it can intentionally lock the Flash by writing a non-0xA5 value to
FLKEY from software.
Read:
When read, bits 1–0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash writes/erases disabled until the next reset.
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21. EEPROM
C8051F700/1/4/5/8/9 and C8051F712/3 devices have hardware which emulates 32 bytes of non-volatile,
byte-programmable EEPROM data space. The module mirrors each non-volatile byte through 32 bytes of
volatile data space. This data space can be accessed indirectly through EEADDR and EEDATA. Users can
copy the complete 32-byte image between EEPROM space and volatile space using controls in the
EECNTL SFR.
EEKEY
EEADDR
EEDATA
EECNTL
32 Bytes
EEPROM
32 Bytes RAM
EEPROM Control
Logic
Figure 21.1. EEPROM Block Diagram
21.1. RAM Reads and Writes
In order to perform EEPROM reads and writes, the EEPROM control logic must be enabled by setting
EEEN (EECNTL.7).
32 bytes of RAM can be accessed indirectly through EEADDR and EEDATA. To write to a byte of RAM,
write address of byte to EEADDR and then write the value to be written to EEDATA. To read a byte from
RAM, write address of byte to be read to EEADDR. The value stored at that address can then be read from
EEDATA.
21.2. Auto Increment
When AUTOINC (EECNTL.0) is set, EEADDR will increment by one after each write to EEDATA and each
read from EEDATA. When Auto Increment is enabled and EEADDR reaches the top address of dedicated
RAM space, the next write to or read from EEDATA will cause EEADDR to wrap along the address bound-
ary, which will set the address to 0.
21.3. Interfacing with the EEPROM
The EEPROM is accessed through the dedicated 32 bytes of RAM. Writes to EEPROM are allowed only
after writes have been enabled (see “21.4. EEPROM Security” ). The contents of the EEPROM can be
uploaded to the RAM by setting EEREAD (EECNTL.2). Contents of RAM can be downloaded to EEPROM
by setting EEWRT (EENTL.1).
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C8051F70x/71x
21.4. EEPROM Security
RAM can only be downloaded to EEPROM after firmware writes a sequence of two bytes to EEKEY. In
order to enable EEPROM writes:
1. Write the first EEPROM key code byte to EEKEY: 0x55
2. Write the second EEPROM key code byte to EEKEY: 0xAA
After a EEPROM writes have been enabled and a single write has executed, the control logic locks
EEPROM writes until the two-byte unlock sequence has been entered into EEKEY again.
The protection state of the EEPROM can be observed by reading EEPSTATE (EEKEY2:0). This state can
be read at any time without affecting the EEPROM’s protection state.
if the two-byte unlock sequence is entered incorrectly, or if a write is attempted without first entering the
two-byte sequence, EEPROM writes will be locked until the next power-on reset.
SFR Definition 21.1. EEADDR: EEPROM Byte Address
Bit
7
6
5
4
3
2
1
0
EEADDR[4:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
0
0
0
0
0
SFR Address = 0xB6; SFR Page = All Pages
Bit
Name
Description
7:5
Unused
Unused. Read = 000b; Write = Don’t Care
4:0 EEADDR[4:0] EEPROM Byte Address
Selects one of 32 EEPROM bytes to read/write.
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SFR Definition 21.2. EEDATA: EEPROM Byte Data
Bit
7
6
5
4
3
2
1
0
EEDATA[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xD1; SFR Page = All Pages
Bit
Name
Description
E2PROM Data
The EEDATA register is
Write
Read
7:0
EEDATA[7:0]
Writes byte to location
stored in EEADDR.
Returns contents at loca-
tion stored in EEADDR.
used to read bytes from the
EEPROM space and write
bytes to EEPROM space.
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SFR Definition 21.3. EECNTL: EEPROM Control
Bit
7
6
5
4
3
2
1
0
EEEN
EEREAD
EEWRT AUTOINC
R/W
Name
Type
Reset
R/W
0
R
0
0
0
0
0
0
1
SFR Address = 0xC5; SFR Page = F
Bit
Name
Description
7
EEEN
EEPROM Enable
0: EEPROM control logic disabled.
1: EEPROM control logic enabled. EEPROM reads and writes can be performed.
Reserved. Read = variable; Write = Don’t Care
Reserved. Read = 0b, Write = 0
6:4
3
Reserved
Reserved
EEREAD
2
EEPROM 32-Byte Read
0: Does nothing.
1: 32 bytes of EEPROM Data will be read from Flash to internal RAM.
1
0
EEWRITE
AUTOINC
EEPROM 32-Byte Write
0: Does nothing.
1: 32 bytes of EEPROM Data will be written from internal RAM to Flash.
Auto Increment
0: Disable auto-increment.
1: Enable auto-increment.
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SFR Definition 21.4. EEKEY: EEPROM Protect Key
Bit
7
6
5
4
3
2
1
0
EEKEY
W
EEPSTATE/EEKEY
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xC6; SFR Page = F
Bit
Name
Description
Write
The sequence 0x55
Read
7:0
EEKEY
EEPROM Key
0xAA must be written to
enable EEPROM writes
and erases
Protects the EEPROM from
inadvertent writes and
erases.
1:0
EEPSTATE
00: Write/Erase is not
enabled
01: The first key has
been written
10: Write/Erase is
enabled
EEPROM Protection State
These bytes show whether
Flash writes/erases have
been enabled, disabled, or
locked.
11: EEPROM is locked
from further
writes/erases
Rev. 0.2
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C8051F70x/71x
22. Power Management Modes
The C8051F70x/71x devices have three software programmable power management modes: Idle, Stop,
and Suspend. Idle mode and Stop mode are part of the standard 8051 architecture, while Suspend mode
is an enhanced power-saving mode implemented by the high-speed oscillator peripheral.
Idle mode halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted,
all interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is
stopped (analog peripherals remain in their selected states; the external oscillator is not affected). Sus-
pend mode is similar to Stop mode in that the internal oscillator and CPU are halted, but the device can
wake on events such as a Port Mismatch, Comparator low output, or a Timer 3 overflow. 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 and Suspend mode consume the least
power because the majority of the device is shut down with no clocks active. SFR Definition 22.1 describes
the Power Control Register (PCON) used to control the C8051F70x/71x's Stop and Idle power manage-
ment modes. Suspend mode is controlled by the SUSPEND bit in the OSCICN register (SFR Definition
25.3).
Although the C8051F70x/71x has Idle, Stop, and Suspend modes available, more control over the device
power can be achieved by enabling/disabling individual peripherals as needed. Each analog peripheral
can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers or
serial buses, draw little power when they are not in use. Turning off oscillators lowers power consumption
considerably, at the expense of reduced functionality.
22.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the hardware to halt the CPU and enter Idle mode as
soon as the instruction that sets the bit completes execution. All internal registers and memory maintain
their original data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
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. Therefore, instructions that set the IDLE bit should be followed by an instruction that has two
or more opcode 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 Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby termi-
nate 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 pro-
vides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefi-
146
Rev. 0.2
C8051F70x/71x
nitely, waiting for an external stimulus to wake up the system. Refer to Section “24. Watchdog Timer” on
page 155 for more information on the use and configuration of the WDT.
22.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the controller core to enter Stop mode as soon as the
instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital
peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral
(including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop
mode can only be terminated by an internal or external reset. On reset, the device performs the normal
reset sequence and begins program execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the
MCD timeout of 100 µs.
22.3. Suspend Mode
Suspend mode allows a system running from the internal oscillator to go to a very low power state similar
to Stop mode, but the processor can be awakened by certain events without requiring a reset of the device.
Setting the SUSPEND bit (OSCICN.5) causes the hardware to halt the CPU and the high-frequency inter-
nal oscillator, and go into Suspend mode as soon as the instruction that sets the bit completes execution.
All internal registers and memory maintain their original data. Most digital peripherals are not active in Sus-
pend mode. The exception to this is the Port Match feature and Timer 3, when it is run from an external
oscillator source.
Note that the clock divider bits CLKDIV[2:0] in register CLKSEL must be set to "divide by 1" when entering
Suspend mode.
Suspend mode can be terminated by five types of events, a port match (described in Section “26.5. Port
Match” on page 176), a Timer 3 overflow (described in Section “31.3. Timer 3” on page 261), a comparator
low output (if enabled), a capacitive sense greater-than comparator interrupt, or a device reset event. In
order to run Timer 3 in Suspend mode, the timer must be configured to clock from the external clock
source. When Suspend mode is terminated, the device will continue execution on the instruction following
the one that set the SUSPEND bit. If the wake event (port match or Timer 3 overflow) was configured to
generate an interrupt, the interrupt will be serviced upon waking the device. If Suspend mode is terminated
by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execu-
tion at address 0x0000.
Rev. 0.2
147
C8051F70x/71x
SFR Definition 22.1. PCON: Power Control
Bit
7
6
5
4
3
2
1
0
GF[5:0]
R/W
STOP
IDLE
Name
Type
Reset
R/W
0
R/W
0
0
0
0
0
0
0
SFR Address = 0x87; SFR Page = All Pages
Bit
Name
Function
7:2
GF[5:0]
General Purpose Flags 5–0.
These are general purpose flags for use under software control.
1
0
STOP
IDLE
Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
1: CPU goes into Stop mode (internal oscillator stopped).
IDLE: Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts,
Serial Ports, and Analog Peripherals are still active.)
148
Rev. 0.2
C8051F70x/71x
23. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
CIP-51 halts program execution
Special Function Registers (SFRs) are initialized to their defined reset values
External Port pins are forced to a known state
Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled dur-
ing and after the reset. For V
Monitor and power-on resets, the RST pin is driven low until the device
DD
exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter-
nal oscillator. The Watchdog Timer is enabled with the system clock divided by 12 as its clock source. Pro-
gram execution begins at location 0x0000.
VDD
Power On
Reset
Supply
Monitor
+
-
'0'
RST
Enable
Comparator 0
(wired-OR)
Px.x
Px.x
+
-
C0RSEF
Missing
Clock
Detector
(one-
shot)
Reset
Funnel
PCA
WDT
(Software Reset)
EN
SWRSF
EN
Errant
FLASH
Operation
System
Clock
CIP-51
System Reset
Microcontroller
Core
Extended Interrupt
Handler
Figure 23.1. Reset Sources
Rev. 0.2
149
C8051F70x/71x
23.1. Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low until V settles above
DD
V
. A delay occurs before the device is released from reset; the delay decreases as the V ramp time
DD
RST
increases (V
ramp time is defined as how fast V
ramps from 0 V to V ). Figure 23.2. plots the
RST
DD
DD
power-on and V
monitor reset timing. The maximum V
ramp time is 1 ms; slower ramp times may
DD
DD
cause the device to be released from reset before V reaches the V
level. For ramp times less than
DD
RST
1 ms, the power-on reset delay (T
) is typically less than 10 ms.
PORDelay
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data mem-
ory should be assumed to be undefined after a power-on reset. The V
monitor is enabled following a
DD
power-on reset.
VDD
VRST
t
/RST
Logic HIGH
TPORDelay
Logic LOW
VDD
Power-On
Reset
Monitor
Reset
Figure 23.2. Power-On and V Monitor Reset Timing
DD
150
Rev. 0.2
C8051F70x/71x
23.2. Power-Fail Reset / V Monitor
DD
When a power-down transition or power irregularity causes V
to drop below V , the power supply
RST
DD
monitor will drive the RST pin low and hold the CIP-51 in a reset state (see Figure 23.2). When V returns
DD
to a level above V
, the CIP-51 will be released from the reset state. Even though internal data memory
RST
contents are not altered by the power-fail reset, it is impossible to determine if V dropped below the level
DD
required for data retention. If the PORSF flag reads 1, the data may no longer be valid. The V monitor is
DD
enabled after power-on resets. Its defined state (enabled/disabled) is not altered by any other reset source.
For example, if the V monitor is disabled by code and a software reset is performed, the V monitor will
DD
DD
still be disabled after the reset.
Important Note: If the V monitor is being turned on from a disabled state, it should be enabled before it
DD
is selected as a reset source. Selecting the V monitor as a reset source before it is enabled and stabi-
DD
lized may cause a system reset. In some applications, this reset may be undesirable. If this is not desirable
in the application, a delay should be introduced between enabling the monitor and selecting it as a reset
source. The procedure for enabling the V monitor and configuring it as a reset source from a disabled
DD
state is shown below:
1. Enable the V monitor (VDMEN bit in VDM0CN = 1).
DD
2. If necessary, wait for the V monitor to stabilize.
DD
3. Select the V monitor as a reset source (PORSF bit in RSTSRC = 1).
DD
See Figure 23.2 for V
monitor timing; note that the power-on-reset delay is not incurred after a V
DD
DD
monitor reset. See Section “7. Electrical Characteristics” on page 40 for complete electrical characteristics
of the V monitor.
DD
Rev. 0.2
151
C8051F70x/71x
SFR Definition 23.1. VDM0CN: V Monitor Control
DD
Bit
7
6
5
4
3
2
1
0
VDMEN VDDSTAT
Name
Type
Reset
R/W
R
R
0
R
0
R
0
R
0
R
0
R
0
Varies
Varies
SFR Address = 0xFF; SFR Page = All Pages
Bit
Name
Function
7
VDMEN
V
Monitor Enable.
DD
This bit turns the V monitor circuit on/off. The V Monitor cannot generate sys-
DD
DD
tem resets until it is also selected as a reset source in register RSTSRC (SFR Def-
inition 23.2). Selecting the V monitor as a reset source before it has stabilized
DD
may generate a system reset. In systems where this reset would be undesirable, a
delay should be introduced between enabling the V Monitor and selecting it as a
DD
reset source.
0: V Monitor Disabled.
DD
1: V Monitor Enabled.
DD
6
VDDSTAT
UNUSED
V
Status.
DD
This bit indicates the current power supply status (V Monitor output).
0: V is at or below the V monitor threshold.
1: V is above the V monitor threshold.
DD
DD
DD
DD
DD
5:0
Unused. Read = 000000b; Write = Don’t care.
23.3. External Reset
The external RST pin provides a means for external circuitry to force the device into a reset state. Assert-
ing an active-low signal on the RST pin generates a reset; an external pullup and/or decoupling of the RST
pin may be necessary to avoid erroneous noise-induced resets. See Section “7. Electrical Characteristics”
on page 40 for complete RST pin specifications. The PINRSF flag (RSTSRC.0) is set on exit from an exter-
nal reset.
23.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system
clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a
MCD reset, the MCDRSF flag (RSTSRC.2) will read 1, signifying the MCD as the reset source; otherwise,
this bit reads 0. Writing a 1 to the MCDRSF bit enables the Missing Clock Detector; writing a 0 disables it.
The state of the RST pin is unaffected by this reset.
152
Rev. 0.2
C8051F70x/71x
23.5. Comparator0 Reset
Comparator0 can be configured as a reset source by writing a 1 to the C0RSEF flag (RSTSRC.5).
Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on
chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-
inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into
the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read 1 signifying
Comparator0 as the reset source; otherwise, this bit reads 0. The state of the RST pin is unaffected by this
reset.
23.6. Watchdog Timer Reset
The programmable Watchdog Timer (WDT) can be used to prevent software from running out of control
during a system malfunction. The WDT function can be enabled or disabled by software as described in
Section “24. Watchdog Timer” on page 155. If a system malfunction prevents user software from updating
the WDT, a reset is generated and the WDTRSF bit (RSTSRC.3) is set to 1. The state of the RST pin is
unaffected by this reset.
23.7. Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
A Flash write or erase is attempted above user code space. This occurs when PSWE is set to 1 and a MOVX
write operation targets an address above address 0x3DFF.
A Flash read is attempted above user code space. This occurs when a MOVC operation targets an address
above address 0x3DFF.
A Program read is attempted above user code space. This occurs when user code attempts to branch to an
address above 0x3DFF.
A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section “20.3. Security
Options” on page 135).
The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by
this reset.
23.8. Software Reset
Software may force a reset by writing a 1 to the SWRSF bit (RSTSRC.4). The SWRSF bit will read 1 fol-
lowing a software forced reset. The state of the RST pin is unaffected by this reset.
Rev. 0.2
153
C8051F70x/71x
SFR Definition 23.2. RSTSRC: Reset Source
Bit
7
6
5
4
3
2
1
0
FERROR C0RSEF
SWRSF WDTRSF MCDRSF
PORSF
PINRSF
Name
Type
Reset
R
0
R
R/W
R/W
R
R/W
R/W
R
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0xEF; SFR Page = All Pages
Bit
Name
Description
Write
Read
7
UNUSED
Don’t care.
N/A
0
Unused.
6
5
4
3
2
FERROR
C0RSEF
SWRSF
Set to 1 if Flash
read/write/erase error
caused the last reset.
Flash Error Reset Flag.
Writing a 1 enables
Comparator0 as a reset
source (active-low).
Set to 1 if Comparator0
caused the last reset.
Comparator0 Reset Enable
and Flag.
Writing a 1 forces a sys-
tem reset.
Set to 1 if last reset was
caused by a write to
SWRSF.
Software Reset Force and
Flag.
WDTRSF
MCDRSF
N/A
Set to 1 if Watchdog Timer
overflow caused the last
reset.
Watchdog Timer Reset Flag.
Writing a 1 enables the
Missing Clock Detector.
Set to 1 if Missing Clock
Detector timeout caused
Missing Clock Detector
Enable and Flag.
The MCD triggers a reset the last reset.
if a missing clock condition
is detected.
1
PORSF
Writing a 1 enables the
monitor as a reset
source.
Set to 1 anytime a power-
Power-On / V Monitor
DD
V
on or V monitor reset
DD
DD
Reset Flag, and V monitor
DD
occurs.
When set to 1 all other
Reset Enable.
Writing 1 to this bit
before the V monitor RSTSRC flags are inde-
DD
is enabled and stabilized terminate.
may cause a system
reset.
0
PINRSF
N/A
Set to 1 if RST pin caused
the last reset.
HW Pin Reset Flag.
Note: Do not use read-modify-write operations on this register
154
Rev. 0.2
C8051F70x/71x
24. Watchdog Timer
The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. A WDT overflow
will force the MCU into the reset state. To prevent the reset, the WDT must be restarted by application soft-
ware before overflow. If the system experiences a software or hardware malfunction preventing the soft-
ware from restarting the WDT, the WDT will overflow and cause a reset.
Following a reset the WDT is automatically enabled and running with the default maximum time interval. 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.
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 24.1.
24.1. Enable/Reset WDT
The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's applica-
tion 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.
24.2. Disable WDT
Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment
illustrates disabling the WDT:
CLR EA
; disable all interrupts
MOV WDTCN,#0DEh ; disable software watchdog timer
MOV WDTCN,#0ADh
SETB EA
; 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.
24.3. 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 always
intending to use the watchdog should write 0xFF to WDTCN in the initialization code.
24.4. Setting WDT Interval
WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equation:
4^(3+WDTCN[2-0]) x Tsysclk ;where Tsysclk is the system clock period.
For a 3 MHz system clock, this provides an interval range of 0.021 to 349.5 ms. WDTCN.7 must be logic 0
when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] reads 111b
after a system reset.
Rev. 0.2
155
C8051F70x/71x
SFR Definition 24.1. WDTCN: Watchdog Timer Control
Bit
7
6
5
4
3
2
1
0
WDT[7:0]
R/W
Name
Type
Reset
0
0
0
1
0
1
1
1
SFR Address = 0xE3; SFR Page = All Pages
Bit
Name
Description
Write
Writing 0xA5 both
Read
7:0
WDT[7:0]
WDT Control.
enables and reloads the
WDT.
Writing 0xDE followed
within 4 system clocks by
0xAD disables the WDT.
Writing 0xFF locks out
the disable feature.
4
WDTSTATUS Watchdog Status Bit.
0: WDT is inactive
1: WDT is active
2:0 WDTTIMEOUT Watchdog Timeout Interval WDTCN[2:0] bits set the
Bits.
Watchdog Timeout Inter-
val. When writing these
bits, WDTCN[7] must be
set to 0.
156
Rev. 0.2
C8051F70x/71x
25. Oscillators and Clock Selection
C8051F70x/71x devices include a programmable internal high-frequency oscillator and an external oscilla-
tor drive circuit. The internal high-frequency oscillator can be enabled/disabled and calibrated using the
OSCICN and OSCICL registers, as shown in Figure 25.1. The system clock can be sourced by the exter-
nal oscillator circuit or the internal oscillator (default). The internal oscillator offers a selectable post-scaling
feature, which is initially set to divide the clock by 8.
Option 2 – RC Mode
OSCICL
OSCICN
CLKSEL
VDD
XTAL2
ProgrammableEN
Internal Clock
Generator
Option 4 – CMOS Mode
XTAL2
CLKRDY
SYSCLK
n
Clock Divider
n
Option 1 – Crystal Mode
XTAL1
Clock Divider
Input
Circuit
10M
OSC
XTAL2
Option 3 – C Mode
XTAL2
OSCXCN
Figure 25.1. Oscillator Options
25.1. System Clock Selection
The system clock source for the MCU can be selected using the CLKSEL register. The clock selected as
the system clock can be divided by 1, 2, 4, 8, 16, 32, 64, or 128. When switching between two clock divide
values, the transition may take up to 128 cycles of the undivided clock source. The CLKRDY flag can be
polled to determine when the new clock divide value has been applied. The clock divider must be set to
"divide by 1" when entering Suspend mode. The system clock source may also be switched on-the-fly. The
switchover takes effect after one clock period of the slower oscillator.
Rev. 0.2
157
C8051F70x/71x
SFR Definition 25.1. CLKSEL: Clock Select
Bit
7
6
5
4
3
2
1
0
Name CLKRDY
CLKDIV[2:0]
CLKSEL[2:0]
Type
R
0
R/W
0
R/W
0
R/W
0
R
0
R/W
0
R/W
0
R/W
0
Reset
SFR Address = 0xBD; SFR Page= F
Bit
Name
Function
7
CLKRDY
System Clock Divider Clock Ready Flag.
0: The selected clock divide setting has not been applied to the system clock.
1: The selected clock divide setting has been applied to the system clock.
6:4
CLKDIV
System Clock Divider Bits.
Selects the clock division to be applied to the selected source (internal or external).
000: Selected clock is divided by 1.
001: Selected clock is divided by 2.
010: Selected clock is divided by 4.
011: Selected clock is divided by 8.
100: Selected clock is divided by 16.
101: Selected clock is divided by 32.
110: Selected clock is divided by 64.
111: Selected clock is divided by 128.
3
Reserved Unused.
Read = 0b. Must write 0b.
2:0 CLKSEL[2:0] System Clock Select.
Selects the oscillator to be used as the undivided system clock source.
000: Internal Oscillator
001: External Oscillator
All other values reserved.
158
Rev. 0.2
C8051F70x/71x
25.2. Programmable Internal High-Frequency (H-F) Oscillator
All C8051F70x/71x devices include a programmable internal high-frequency oscillator that defaults as the
system clock after a system reset. The internal oscillator period can be adjusted via the OSCICL register
as defined by SFR Definition 25.2.
On C8051F70x/71x devices, OSCICL is factory calibrated to obtain a 24.5 MHz base frequency.
The internal oscillator output frequency may be divided by 1, 2, 4, or 8, as defined by the IFCN bits in reg-
ister OSCICN. The divide value defaults to 8 following a reset.
The precision oscillator supports a spread spectrum mode which modulates the output frequency in order
to reduce the EMI generated by the system. When enabled (SSE = 1), the oscillator output frequency is
modulated by a stepped triangle wave whose frequency is equal to the oscillator frequency divided by 384
(63.8 kHz using the factory calibration). The maximum deviation from the center frequency is ±0.75%. The
output frequency updates occur every 32 cycles and the step size is typically 0.25% of the center fre-
quency.
SFR Definition 25.2. OSCICL: Internal H-F Oscillator Calibration
Bit
7
6
5
4
3
2
1
0
OSCICL[6:0]
R/W
Name
Type
Reset
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0xBF; SFR Page = F
Bit Name
6:0 OSCICL[7:0] Internal Oscillator Calibration Bits.
Function
These bits determine the internal oscillator period. When set to 00000000b, the H-F
oscillator operates at its fastest setting. When set to 11111111b, the H-F oscillator
operates at its slowest setting. The reset value is factory calibrated to generate an
internal oscillator frequency of 24.5 MHz.
Rev. 0.2
159
C8051F70x/71x
SFR Definition 25.3. OSCICN: Internal H-F Oscillator Control
Bit
7
6
5
4
3
2
1
0
IOSCEN
IFRDY
SUSPEND STSYNC
SSE
IFCN[1:0]
R/W
Name
Type
Reset
R/W
1
R
1
R/W
0
R
0
R/W
0
R
0
0
0
SFR Address = 0xA9; SFR Page = F
Bit
Name
Function
7
IOSCEN
Internal H-F Oscillator Enable Bit.
0: Internal H-F Oscillator Disabled.
1: Internal H-F Oscillator Enabled.
6
5
IFRDY
Internal H-F Oscillator Frequency Ready Flag.
0: Internal H-F Oscillator is not running at programmed frequency.
1: Internal H-F Oscillator is running at programmed frequency.
SUSPEND Internal Oscillator Suspend Enable Bit.
Setting this bit to logic 1 places the internal oscillator in SUSPEND mode. The inter-
nal oscillator resumes operation when one of the SUSPEND mode awakening
events occurs.
4
3
STSYNC
Suspend Timer Synchronization Bit.
This bit is used to indicate when it is safe to read and write the registers associated
with the suspend wake-up timer. If a suspend wake-up source other than Timer 3
has brought the oscillator out of suspend mode, it make take up to three timer clocks
before the timer can be read or written.
0: Timer 3 registers can be read safely.
1: Timer 3 register reads and writes should not be performed.
SSE
Spread Spectrum Enable.
Spread spectrum enable bit.
0: Spread Spectrum clock dithering disabled.
1: Spread Spectrum clock dithering enabled.
2
Unused
Unused. Read = 0b; Write = Don’t Care
1:0
IFCN[1:0] Internal H-F Oscillator Frequency Divider Control Bits.
00: SYSCLK derived from Internal H-F Oscillator divided by 8.
01: SYSCLK derived from Internal H-F Oscillator divided by 4.
10: SYSCLK derived from Internal H-F Oscillator divided by 2.
11: SYSCLK derived from Internal H-F Oscillator divided by 1.
160
Rev. 0.2
C8051F70x/71x
25.3. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crys-
tal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 25.1. A
10 Mresistor also must be wired across the XTAL2 and XTAL1 pins for the crystal/resonator configura-
tion. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as
shown in Option 2, 3, or 4 of Figure 25.1. The type of external oscillator must be selected in the OSCXCN
register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 25.4).
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is
enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar
should be configured to skip the Port pins used by the oscillator circuit; see Section “26.3. Priority Crossbar
Decoder” on page 171 for Crossbar configuration. Additionally, when using the external oscillator circuit in
crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs.
In CMOS clock mode, the associated pin should be configured as a digital input. See Section “26.4. Port
I/O Initialization” on page 173 for details on Port input mode selection.
Rev. 0.2
161
C8051F70x/71x
SFR Definition 25.4. OSCXCN: External Oscillator Control
Bit
7
6
5
4
3
2
1
0
XTLVLD
XOSCMD[2:0]
XFCN[2:0]
Name
Type
Reset
R
0
R/W
0
R
0
R/W
0
0
0
0
0
SFR Address = 0xB5; SFR Page = F
Bit
Name
Function
7
XTLVLD
Crystal Oscillator Valid Flag.
(Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
6:4 XOSCMD[2:0] External Oscillator Mode Select.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
3
UNUSED
Read = 0; Write = Don’t Care
2:0
XFCN[2:0]
External Oscillator Frequency Control Bits.
Set according to the desired frequency for Crystal or RC mode.
Set according to the desired K Factor for C mode.
XFCN
000
001
010
011
100
101
110
111
Crystal Mode
f 32 kHz
RC Mode
f 25 kHz
C Mode
K Factor = 0.87
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
K Factor = 180
K Factor = 664
K Factor = 1590
32 kHz f 84 kHz
84 kHz f 225 kHz
25 kHz f 50 kHz
50 kHz f 100 kHz
225 kHz f 590 kHz 100 kHz f 200 kHz
590 kHz f 1.5 MHz 200 kHz f 400 kHz
1.5 MHz f 4 MHz 400 kHz f 800 kHz
4 MHz f 10 MHz
800 kHz f 1.6 MHz
10 MHz f 30 MHz 1.6 MHz f 3.2 MHz
162
Rev. 0.2
C8051F70x/71x
25.3.1. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 25.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 25.4 (OSCXCN register). For
example, an 11.0592 MHz crystal requires an XFCN setting of 111b and a 32.768 kHz Watch Crystal
requires an XFCN setting of 001b. After an external 32.768 kHz oscillator is stabilized, the XFCN setting
can be switched to 000 to save power. It is recommended to enable the missing clock detector before
switching the system clock to any external oscillator source.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The rec-
ommended procedure is:
1. Force XTAL1 and XTAL2 to a low state. This involves enabling the Crossbar and writing 0 to the port
pins associated with XTAL1 and XTAL2.
2. Configure XTAL1 and XTAL2 as analog inputs.
3. Enable the external oscillator.
4. Wait at least 1 ms.
5. Poll for XTLVLD = 1.
6. If desired, enable the Missing Clock Detector.
7. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
The capacitors shown in the external crystal configuration provide the load capacitance required by the
crystal for correct oscillation. These capacitors are "in series" as seen by the crystal and "in parallel" with
the stray capacitance of the XTAL1 and XTAL2 pins.
Note: The desired load capacitance depends upon the crystal and the manufacturer. Please refer to the crystal data
sheet when completing these calculations.
For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should
use the configuration shown in Figure 25.1, Option 1. The total value of the capacitors and the stray capac-
itance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors
yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 25.2.
Rev. 0.2
163
C8051F70x/71x
XTAL1
XTAL2
10M
32.768 kHz
22pF*
22pF*
* Capacitor values depend on
crystal specifications
Figure 25.2. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram
25.3.2. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 25.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine 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, according to Equation 25.1,
where f = the frequency of oscillation in MHz, C = the capacitor value in pF, and R = the pull-up resistor
value in k.
Equation 25.1. RC Mode Oscillator Frequency
f = 1.23 103 R C
For example: If the frequency desired is 100 kHz, let R = 246 k and C = 50 pF:
3
3
f = 1.23( 10 ) / RC = 1.23 ( 10 ) / [ 246 x 50 ] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 25.4, the required XFCN setting is 010b.
164
Rev. 0.2
C8051F70x/71x
25.3.3. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 25.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation according to Equation 25.2, where f = the frequency of
oscillation in MHz, C = the capacitor value in pF, and V = the MCU power supply in Volts.
DD
Equation 25.2. C Mode Oscillator Frequency
f = KF R VDD
For example: Assume V = 3.0 V and f = 150 kHz:
DD
f = KF / (C x VDD)
0.150 MHz = KF / (C x 3.0)
Since the frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 25.4
(OSCXCN) as KF = 22:
0.150 MHz = 22 / (C x 3.0)
C x 3.0 = 22 / 0.150 MHz
C = 146.6 / 3.0 pF = 48.8 pF
Therefore, the XFCN value to use in this example is 011b and C = 50 pF.
Rev. 0.2
165
C8051F70x/71x
26. Port Input/Output
Digital and analog resources are available through 64 I/O pins. Each of the Port pins P0.0-P2.7 can be
defined as general-purpose I/O (GPIO), assigned to one of the internal digital resources, or assigned to an
analog function as shown in Figure 26.4. The designer has complete control over which functions are
assigned, limited only by the number of physical I/O pins. This resource assignment flexibility is achieved
through the use of a Priority Crossbar Decoder. The state of a Port I/O pin can always be read in the corre-
sponding Port latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 26.4 and Figure 26.5). The registers XBR0 and XBR1, defined in SFR Definition 26.1 and SFR
Definition 26.2, are used to select internal digital functions.
All Port I/Os are tolerant of voltages up to 2 V above the V supply (refer to Figure 26.2 for the Port cell
DD
circuit). The Port I/O cells are configured as either push-pull or open-drain in the Port Output Mode regis-
ters (PnMDOUT, where n = 0,1). Complete Electrical Specifications for Port I/O are given in Section
“7. Electrical Characteristics” on page 40.
Port Match
XBR0, XBR1,
P0MASK, P0MAT
P1MASK, P1MAT
PnSKIP Registers
External Interrupts
EX0 and EX1
Priority
Decoder
PnMDOUT,
PnMDIN , PnDRV
Registers
2
UART
SPI
Highest
Priority
4
2
P0.0
P0.7
P0
I/O
Cells
8
8
SMBus
Digital
Crossbar
P1.0
P1.7
P1
I/O
Cells
2
CP0
Outputs
SYSCLK
PCA
P2.0
P2
I/O
Cells
8
4
2
P2.7
P3.0
P3
I/O
Lowest
Priority
T0, T1
Cells
P3.7
P4.0
8
P4
I/O
Cells
P0
P1
(P0.0-P0.7)
P4.7
P5.0
8
(P1.0-P1.7)
P5
I/O
Cells
P5.7
P6.0
P6 I/O Cells
(digital only)
P6.5
To CS0
To Analog Peripherals
(ADC0, CP0, VREF, XTAL)
Figure 26.1. Port I/O Functional Block Diagram
166
Rev. 0.2
C8051F70x/71x
26.1. Port I/O Modes of Operation
Port pins P0.0 - P6.5 use the Port I/O cell shown in Figure 26.2. Each Port I/O cell can be configured by
software for analog I/O or digital I/O using the PnMDIN registers. On reset, all Port I/O cells default to a
high impedance state with weak pull-ups enabled. Until the crossbar is enabled (XBARE = 1), both the
high and low port I/O drive circuits are explicitly disabled on all crossbar pins.
26.1.1. Port Pins Configured for Analog I/O
Any pins to be used as Comparator or ADC input, Capacitive Sense input, external oscillator input/output,
VREF output, or AGND connection should be configured for analog I/O (PnMDIN.n = 1). When a pin is
configured for analog I/O, its weak pullup, digital driver, and digital receiver are disabled. Port pins config-
ured for analog I/O will always read back a value of 0.
Configuring pins as analog I/O saves power and isolates the Port pin from digital interference. Port pins
configured as digital I/O may still be used by analog peripherals; however, this practice is not recom-
mended and may result in measurement errors.
26.1.2. Port Pins Configured For Digital I/O
Any pins to be used by digital peripherals (UART, SPI, SMBus, etc.), external event trigger functions, or as
GPIO should be configured as digital I/O (PnMDIN.n = 1). For digital I/O pins, one of two output modes
(push-pull or open-drain) must be selected using the PnMDOUT registers.
Push-pull outputs (PnMDOUT.n = 1) drive the Port pad to the VDD or GND supply rails based on the out-
put logic value of the Port pin. Open-drain outputs have the high side driver disabled; therefore, they only
drive the Port pad to GND when the output logic value is 0 and become high impedance inputs (both high
low drivers turned off) when the output logic value is 1.
When a digital I/O cell is placed in the high impedance state, a weak pull-up transistor pulls the Port pad to
the VDD supply voltage to ensure the digital input is at a defined logic state. Weak pull-ups are disabled
when the I/O cell is driven to GND to minimize power consumption, and they may be globally disabled by
setting WEAKPUD to 1. The user should ensure that digital I/O are always internally or externally pulled or
driven to a valid logic state to minimize power consumption. Port pins configured for digital I/O always read
back the logic state of the Port pad, regardless of the output logic value of the Port pin.
Rev. 0.2
167
C8051F70x/71x
WEAKPUD
(Weak Pull-Up Disable)
PxMDOUT.x
(1 for push-pull)
(0 for open-drain)
VDD
VDD
XBARE
(Crossbar
Enable)
(WEAK)
PORT
PAD
Px.x – Output
Logic Value
(Port Latch or
Crossbar)
PxMDIN.x
(1 for digital)
GND
(0 for analog)
To/From Analog
Peripheral
Px.x – Input Logic Value
(Reads 0 when pin is configured as an analog I/O)
Figure 26.2. Port I/O Cell Block Diagram
26.1.3. Interfacing Port I/O to 5 V Logic
All Port I/O configured for digital, open-drain operation are capable of interfacing to digital logic operating at
a supply voltage up to 2 V higher than VDD and less than 5.25 V. An external pull-up resistor to the higher
supply voltage is typically required for most systems.
Important Note: In a multi-voltage interface, the external pull-up resistor should be sized to allow a current
of at least 150 µA to flow into the Port pin when the supply voltage is between (VDD + 0. 6V) and
(VDD + 1.0V). Once the Port pin voltage increases beyond this range, the current flowing into the Port pin
is minimal. Figure 26.3 shows the input current characteristics of port pins driven above VDD. The port pin
requires 150 µA peak overdrive current when its voltage reaches approximately (VDD + 0.7 V).
VDD
Vtest (V)
VDD VDD+0.7
0
IVtest
I/O
Cell
-10
IVtest
(µA)
+
-
Vtest
-150
Port I/O Overdrive Test Circuit
Port I/O Overdrive Current vs. Voltage
Figure 26.3. Port I/O Overdrive Current
168
Rev. 0.2
C8051F70x/71x
26.1.4. Increasing Port I/O Drive Strength
Port I/O output drivers support a high and low drive strength; the default is low drive strength. The drive
strength of a Port I/O can be configured using the PnDRV registers. See Section “7. Electrical Characteris-
tics” on page 40 for the difference in output drive strength between the two modes.
26.2. Assigning Port I/O Pins to Analog and Digital Functions
Port I/O pins P0.0–P2.7 can be assigned to various analog, digital, and external interrupt functions. The
Port pins assigned to analog functions should be configured for analog I/O, and Port pins assigned to digi-
tal or external interrupt functions should be configured for digital I/O.
26.2.1. Assigning Port I/O Pins to Analog Functions
Table 26.1 shows all available analog functions that require Port I/O assignments. Port pins selected for
these analog functions should have their corresponding bit in PnSKIP set to 1. This reserves the pin
for use by the analog function and does not allow it to be claimed by the Crossbar. Table 26.1 shows the
potential mapping of Port I/O to each analog function.
Table 26.1. Port I/O Assignment for Analog Functions
Analog Function
PotentiallyAssignable
Port Pins
SFR(s) used for
Assignment
ADC Input
P0.0–P2.7
AMX0P, AMX0N,
PnSKIP, PnMDIN
Comparator0 Input
P0.0–P1.7
CPT0MX, PnSKIP,
PnMDIN
CS0 Input
P2.0–P5.7
P0.0
PnMDIN
Voltage Reference (VREF0)
REF0CN, P0SKIP,
PnMDIN
Ground Reference (AGND)
P0.1
P0.2
REF0CN, P0SKIP
External Oscillator in Crystal Mode (XTAL1)
OSCXCN, P0SKIP,
P0MDIN
External Oscillator in RC, C, or Crystal Mode (XTAL2)
P0.3
OSCXCN, P0SKIP,
P0MDIN
Rev. 0.2
169
C8051F70x/71x
26.2.2. Assigning Port I/O Pins to Digital Functions
Any Port pins not assigned to analog functions may be assigned to digital functions or used as GPIO. Most
digital functions rely on the Crossbar for pin assignment; however, some digital functions bypass the
Crossbar in a manner similar to the analog functions listed above. Port pins used by these digital func-
tions and any Port pins selected for use as GPIO should have their corresponding bit in PnSKIP set
to 1. Table 26.2 shows all available digital functions and the potential mapping of Port I/O to each digital
function.
Table 26.2. Port I/O Assignment for Digital Functions
Digital Function
Potentially Assignable Port Pins
SFR(s) used for
Assignment
UART0, SPI0, SMBus, CP0, Any Port pin available for assignment by the
CP0A, SYSCLK, PCA0 Crossbar. This includes P0.0–P2.7 pins which
(CEX0-2 and ECI), T0 or T1. have their PnSKIP bit set to 0.
Note: The Crossbar will always assign UART0
pins to P0.4 and P0.5.
XBR0, XBR1
Any pin used for GPIO
P0.0–P6.5
P0SKIP, P1SKIP,
P2SKIP
External Memory Interface
P3.0–P6.2
EMI0CF
26.2.3. Assigning Port I/O Pins to External Event Trigger Functions
External event trigger functions can be used to trigger an interrupt or wake the device from a low power
mode when a transition occurs on a digital I/O pin. The event trigger functions do not require dedicated
pins and will function on both GPIO pins (PnSKIP = 1) and pins in use by the Crossbar (PnSKIP = 0).
External event trigger functions cannot be used on pins configured for analog I/O. Table 26.3 shows all
available external event trigger functions.
Table 26.3. Port I/O Assignment for External Event Trigger Functions
Event Trigger Function
Potentially Assignable Port Pins
SFR(s) used for
Assignment
External Interrupt 0
External Interrupt 1
Port Match
P0.0–P0.7
P0.0–P0.7
P0.0–P1.7
IT01CF
IT01CF
P0MASK, P0MAT
P1MASK, P1MAT
170
Rev. 0.2
C8051F70x/71x
26.3. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 26.4) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that
are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.1 if AGND
is used, P0.3 and/or P0.2 if the external oscillator circuit is enabled, P0.6 if the ADC is configured to use
the external conversion start signal (CNVSTR), and any selected ADC or Comparator inputs. The Cross-
bar skips selected pins as if they were already assigned, and moves to the next unassigned pin.
Figure 26.5 shows the Crossbar Decoder priority with pins P0.2 and P0.6 skipped (P0SKIP = 0x44).
P0
P1
P2
SF Signa ls
PIN I/O
TX0
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
RX0
SCK
MISO
MOSI
NSS1
SDA
SCL
CP0
CP0A
SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
Port pin potentially available to peripheral
Notes:
1. NSS is only pinned out in 4-wire SPI Mode
SF Signa ls
Special Function Signals are not assigned by the
crossbar. W hen these signals are enabled, the
Crossbar m ust be m anually configured to skip
their corresponding port pins.
Figure 26.4. Crossbar Priority Decoder—Possible Pin Assignments
Rev. 0.2
171
C8051F70x/71x
P0
P1
P2
SF Signals
PIN I/O
TX0
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
RX0
SCK
MISO
MOSI
NSS1
SDA
SCL
CP0
CP0A
SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P0SKIP[0:7]
P1SKIP[0:7]
P2SKIP[0:7]
Port pin potentially available to peripheral
Notes:
SF Signals
1. NSS is only pinned out in 4-wire SPI Mode
Special Function Signals are not assigned by the crossbar.
When these signals are enabled, the CrossBar must be
manually configured to skip their corresponding port pins.
Figure 26.5. Crossbar Priority Decoder Example
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. When
the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and SCL); when
the UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX). UART0 pin
assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART RX0 is
always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized functions have been
assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the
NSSMD1–NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not
be routed to a Port pin.
172
Rev. 0.2
C8051F70x/71x
26.4. Port I/O Initialization
Port I/O initialization consists of the following steps:
1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode register (PnMDIN).
2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output Mode register
(PnMDOUT).
3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
4. Assign Port pins to desired peripherals.
5. Enable the Crossbar (XBARE = 1).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pullup, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this
practice is not recommended.
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a 1 indicates a
digital input, and a 0 indicates an analog input. All pins default to digital inputs on reset. See SFR Definition
26.8 for the PnMDIN register details.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD-
OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is 0, a weak pullup is enabled for all Port I/O config-
ured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is
turned off on an output that is driving a 0 to avoid unnecessary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to 1 enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will determine the
Port I/O pin-assignments based on the XBRn Register settings.
The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers
are disabled while the Crossbar is disabled.
Rev. 0.2
173
C8051F70x/71x
SFR Definition 26.1. XBR0: Port I/O Crossbar Register 0
Bit
7
6
5
4
3
2
1
0
CP0AE
CP0E
SYSCKE
SMB0E
SPI0E
URT0E
Name
Type
Reset
R
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xE1; SFR Page = F
Bit
Name
Function
7:6
5
Unused Unused. Read = 00b; Write = Don’t Care.
CP0AE
CP0E
Comparator0 Asynchronous Output Enable.
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin.
4
3
2
1
Comparator0 Output Enable.
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
SYSCKE
SMB0E
SPI0E
SYSCLK Output Enable.
0: SYSCLK unavailable at Port pin.
1: SYSCLK output routed to Port pin.
SMBus I/O Enable.
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
SPI I/O Enable.
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins. Note that the SPI can be assigned either 3 or 4 GPIO
pins.
0
URT0E
UART I/O Output Enable.
0: UART I/O unavailable at Port pin.
1: UART TX0, RX0 routed to Port pins P0.4 and P0.5.
174
Rev. 0.2
C8051F70x/71x
SFR Definition 26.2. XBR1: Port I/O Crossbar Register 1
Bit
7
6
5
4
3
2
1
0
WEAKPUD XBARE
T1E
T0E
ECIE
PCA0ME[1:0]
R/W R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R
0
0
0
SFR Address = 0xE2; SFR Page = F
Bit
Name
Function
7
WEAKPUD Port I/O Weak Pullup Disable.
0: Weak Pullups enabled (except for Ports whose I/O are configured for analog
mode).
1: Weak Pullups disabled.
6
5
4
3
2
XBARE
T1E
Crossbar Enable.
0: Crossbar disabled.
1: Crossbar enabled.
T1 Enable.
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
T0E
T0 Enable.
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
ECIE
PCA0 External Counter Input Enable.
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Unused
Unused. Read = 0b; Write = Don’t Care.
1:0 PCA0ME[1:0] PCA Module I/O Enable Bits.
00: All PCA I/O unavailable at Port pins.
01: CEX0 routed to Port pin.
10: CEX0, CEX1 routed to Port pins.
11: CEX0, CEX1, CEX2 routed to Port pins.
Rev. 0.2
175
C8051F70x/71x
26.5. Port Match
Port match functionality allows system events to be triggered by a logic value change on P0 or P1. A soft-
ware controlled value stored in the PnMATCH registers specifies the expected or normal logic values of P0
and P1. A Port mismatch event occurs if the logic levels of the Port’s input pins no longer match the soft-
ware controlled value. This allows Software to be notified if a certain change or pattern occurs on P0 or P1
input pins regardless of the XBRn settings.
The PnMASK registers can be used to individually select which P0 and P1 pins should be compared
against the PnMATCH registers. A Port mismatch event is generated if (P0 & P0MASK) does not equal
(P0MATCH & P0MASK) or if (P1 & P1MASK) does not equal (P1MATCH & P1MASK).
A Port mismatch event may be used to generate an interrupt or wake the device from a low power mode,
such as IDLE or SUSPEND. See the Interrupts and Power Options chapters for more details on interrupt
and wake-up sources.
SFR Definition 26.3. P0MASK: Port 0 Mask Register
Bit
7
6
5
4
3
2
1
0
P0MASK[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xF4; SFR Page = 0
Bit Name
7:0 P0MASK[7:0] Port 0 Mask Value.
Function
Selects P0 pins to be compared to the corresponding bits in P0MAT.
0: P0.n pin logic value is ignored and cannot cause a Port Mismatch event.
1: P0.n pin logic value is compared to P0MAT.n.
176
Rev. 0.2
C8051F70x/71x
SFR Definition 26.4. P0MAT: Port 0 Match Register
Bit
7
6
5
4
3
2
1
0
P0MAT[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF3; SFR Page = 0
Bit
Name
Function
7:0
P0MAT[7:0]
Port 0 Match Value.
Match comparison value used on Port 0 for bits in P0MASK which are set to 1.
0: P0.n pin logic value is compared with logic LOW.
1: P0.n pin logic value is compared with logic HIGH.
SFR Definition 26.5. P1MASK: Port 1 Mask Register
Bit
7
6
5
4
3
2
1
0
P1MASK[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xE2; SFR Page = 0
Bit Name
7:0 P1MASK[7:0] Port 1 Mask Value.
Function
Selects P1 pins to be compared to the corresponding bits in P1MAT.
0: P1.n pin logic value is ignored and cannot cause a Port Mismatch event.
1: P1.n pin logic value is compared to P1MAT.n.
Rev. 0.2
177
C8051F70x/71x
SFR Definition 26.6. P1MAT: Port 1 Match Register
Bit
7
6
5
4
3
2
1
0
P1MAT[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xE1; SFR Page = 0
Bit
Name
Function
7:0
P1MAT[7:0]
Port 1 Match Value.
Match comparison value used on Port 1 for bits in P1MASK which are set to 1.
0: P1.n pin logic value is compared with logic LOW.
1: P1.n pin logic value is compared with logic HIGH.
26.6. Special Function Registers for Accessing and Configuring Port I/O
All Port I/O are accessed through corresponding special function registers (SFRs) that are both byte
addressable and bit addressable. When writing to a Port, the value written to the SFR is latched to main-
tain the output data value at each pin. When reading, the logic levels of the Port's input pins are returned
regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the
Port register can always read its corresponding Port I/O pin). The exception to this is the execution of the
read-modify-write instructions that target a Port Latch register as the destination. The read-modify-write
instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ
and MOV, CLR or SETB, when the destination is an individual bit in a Port SFR. For these instructions, the
value of the latch register (not the pin) is read, modified, and written back to the SFR.
Each Port has a corresponding PnSKIP register which allows its individual Port pins to be assigned to dig-
ital functions or skipped by the Crossbar. All Port pins used for analog functions, GPIO, or dedicated digital
functions such as the EMIF should have their PnSKIP bit set to 1.
The Port input mode of the I/O pins is defined using the Port Input Mode registers (PnMDIN). Each Port
cell can be configured for analog or digital I/O. This selection is required even for the digital resources
selected in the XBRn registers, and is not automatic.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD-
OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings.
178
Rev. 0.2
C8051F70x/71x
SFR Definition 26.7. P0: Port 0
Bit
7
6
5
4
3
2
1
0
P0[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0x80; SFR Page = All Pages; Bit Addressable
Bit
Name
P0[7:0] Port 0 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P0.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P0.n Port pin is logic
HIGH. HIGH.
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
SFR Definition 26.8. P0MDIN: Port 0 Input Mode
Bit
7
6
5
4
3
2
1
0
P0MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF1; SFR Page = F
Bit
Name
Function
7:0
P0MDIN[7:0] Analog Configuration Bits for P0.7–P0.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P0.n pin is configured for analog mode.
1: Corresponding P0.n pin is not configured for analog mode.
Rev. 0.2
179
C8051F70x/71x
SFR Definition 26.9. P0MDOUT: Port 0 Output Mode
Bit
7
6
5
4
3
2
1
0
P0MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA4; SFR Page = F
Bit Name
Function
7:0 P0MDOUT[7:0] Output Configuration Bits for P0.7–P0.0 (respectively).
These bits are ignored if the corresponding bit in register P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push-pull.
SFR Definition 26.10. P0SKIP: Port 0 Skip
Bit
7
6
5
4
3
2
1
0
P0SKIP[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xD4; SFR Page = F
Bit
Name
Function
7:0
P0SKIP[7:0] Port 0 Crossbar Skip Enable Bits.
These bits select Port 0 pins to be skipped by the Crossbar Decoder. Port pins
used for analog, special functions or GPIO should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
180
Rev. 0.2
C8051F70x/71x
SFR Definition 26.11. P0DRV: Port 0 Drive Strength
Bit
7
6
5
4
3
2
1
0
P0DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xF9; SFR Page = F
Bit
Name
Function
7:0
P0DRV[7:0] Drive Strength Configuration Bits for P0.7-P0.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P0.n Output has low output drive strength.
1: Corresponding P0.n Output has high output drive strength.
SFR Definition 26.12. P1: Port 1
Bit
7
6
5
4
3
2
1
0
P1[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0x90; SFR Page = All Pages; Bit Addressable
Bit
Name
P1[7:0] Port 1 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P1.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P1.n Port pin is logic
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
Rev. 0.2
181
C8051F70x/71x
SFR Definition 26.13. P1MDIN: Port 1 Input Mode
Bit
7
6
5
4
3
2
1
0
P1MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF2; SFR Page = F
Bit
Name
Function
7:0
P1MDIN[7:0] Analog Configuration Bits for P1.7–P1.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P1.n pin is configured for analog mode.
1: Corresponding P1.n pin is not configured for analog mode.
SFR Definition 26.14. P1MDOUT: Port 1 Output Mode
Bit
7
6
5
4
3
2
1
0
P1MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA5; SFR Page = F
Bit Name
Function
7:0 P1MDOUT[7:0] Output Configuration Bits for P1.7–P1.0 (respectively).
These bits are ignored if the corresponding bit in register P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push-pull.
182
Rev. 0.2
C8051F70x/71x
SFR Definition 26.15. P1SKIP: Port 1 Skip
Bit
7
6
5
4
3
2
1
0
P1SKIP[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xD5; SFR Page = F
Bit
Name
Function
7:0
P1SKIP[7:0] Port 1 Crossbar Skip Enable Bits.
These bits select Port 1 pins to be skipped by the Crossbar Decoder. Port pins
used for analog, special functions or GPIO should be skipped by the Crossbar.
0: Corresponding P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
SFR Definition 26.16. P1DRV: Port 1 Drive Strength
Bit
7
6
5
4
3
2
1
0
P1DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFA; SFR Page = F
Bit
Name
Function
7:0
P1DRV[7:0] Drive Strength Configuration Bits for P1.7–P1.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P1.n Output has low output drive strength.
1: Corresponding P1.n Output has high output drive strength.
Rev. 0.2
183
C8051F70x/71x
SFR Definition 26.17. P2: Port 2
Bit
7
6
5
4
3
2
1
0
P2[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xA0; SFR Page = All Pages; Bit Addressable
Bit
Name
P2[7:0] Port 2 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P2.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P2.n Port pin is logic
HIGH. HIGH.
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
SFR Definition 26.18. P2MDIN: Port 2 Input Mode
Bit
7
6
5
4
3
2
1
0
P2MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF3; SFR Page = F
Bit
Name
Function
7:0
P2MDIN[7:0] Analog Configuration Bits for P2.7–P2.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P2.n pin is configured for analog mode.
1: Corresponding P2.n pin is not configured for analog mode.
184
Rev. 0.2
C8051F70x/71x
SFR Definition 26.19. P2MDOUT: Port 2 Output Mode
Bit
7
6
5
4
3
2
1
0
P2MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA6; SFR Page = F
Bit Name
Function
7:0 P2MDOUT[7:0] Output Configuration Bits for P2.7–P2.0 (respectively).
These bits are ignored if the corresponding bit in register P2MDIN is logic 0.
0: Corresponding P2.n Output is open-drain.
1: Corresponding P2.n Output is push-pull.
SFR Definition 26.20. P2SKIP: Port 2 Skip
Bit
7
6
5
4
3
2
1
0
P2SKIP[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xD6; SFR Page = F
Bit
Name
Function
7:0
P2SKIP[3:0] Port 2 Crossbar Skip Enable Bits.
These bits select Port 2 pins to be skipped by the Crossbar Decoder. Port pins
used for analog, special functions or GPIO should be skipped by the Crossbar.
0: Corresponding P2.n pin is not skipped by the Crossbar.
1: Corresponding P2.n pin is skipped by the Crossbar.
Rev. 0.2
185
C8051F70x/71x
SFR Definition 26.21. P2DRV: Port 2 Drive Strength
Bit
7
6
5
4
3
2
1
0
P2DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFB; SFR Page = F
Bit
Name
Function
7:0
P2DRV[7:0] Drive Strength Configuration Bits for P2.7-P2.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P2.n Output has low output drive strength.
1: Corresponding P2.n Output has high output drive strength.
SFR Definition 26.22. P3: Port 3
Bit
7
6
5
4
3
2
1
0
P3[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xB0; SFR Page = All Pages; Bit Addressable
Bit
Name
P3[7:0] Port 3 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P3.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P3.n Port pin is logic
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
186
Rev. 0.2
C8051F70x/71x
SFR Definition 26.23. P3MDIN: Port 3 Input Mode
Bit
7
6
5
4
3
2
1
0
P3MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF4; SFR Page = F
Bit
Name
Function
7:0
P3MDIN[7:0] Analog Configuration Bits for P3.7–P3.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P3.n pin is configured for analog mode.
1: Corresponding P3.n pin is not configured for analog mode.
SFR Definition 26.24. P3MDOUT: Port 3 Output Mode
Bit
7
6
5
4
3
2
1
0
P3MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xAF; SFR Page = F
Bit Name
Function
7:0 P3MDOUT[7:0] Output Configuration Bits for P3.7–P3.0 (respectively).
These bits are ignored if the corresponding bit in register P3MDIN is logic 0.
0: Corresponding P3.n Output is open-drain.
1: Corresponding P3.n Output is push-pull.
Rev. 0.2
187
C8051F70x/71x
SFR Definition 26.25. P3DRV: Port 3 Drive Strength
Bit
7
6
5
4
3
2
1
0
P3DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFC; SFR Page = F
Bit
Name
Function
7:0
P3DRV[7:0] Drive Strength Configuration Bits for P3.7-P3.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P3.n Output has low output drive strength.
1: Corresponding P3.n Output has high output drive strength.
SFR Definition 26.26. P4: Port 4
Bit
7
6
5
4
3
2
1
0
P4[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xAC; SFR Page = All Pages
Bit
Name
P4[7:0] Port 4 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P4.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P4.n Port pin is logic
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
188
Rev. 0.2
C8051F70x/71x
SFR Definition 26.27. P4MDIN: Port 4 Input Mode
Bit
7
6
5
4
3
2
1
0
P4MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF5; SFR Page = F
Bit
Name
Function
7:0
P4MDIN[7:0] Analog Configuration Bits for P4.7–P4.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P4.n pin is configured for analog mode.
1: Corresponding P4.n pin is not configured for analog mode.
SFR Definition 26.28. P4MDOUT: Port 4 Output Mode
Bit
7
6
5
4
3
2
1
0
P4MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x9A; SFR Page = F
Bit Name
Function
7:0 P4MDOUT[7:0] Output Configuration Bits for P4.7–P4.0 (respectively).
These bits are ignored if the corresponding bit in register P4MDIN is logic 0.
0: Corresponding P4.n Output is open-drain.
1: Corresponding P4.n Output is push-pull.
Rev. 0.2
189
C8051F70x/71x
SFR Definition 26.29. P4DRV: Port 4 Drive Strength
Bit
7
6
5
4
3
2
1
0
P4DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFD; SFR Page = F
Bit
Name
Function
7:0
P4DRV[7:0] Drive Strength Configuration Bits for P4.7-P4.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P4.n Output has low output drive strength.
1: Corresponding P4.n Output has high output drive strength.
SFR Definition 26.30. P5: Port 5
Bit
7
6
5
4
3
2
1
0
P5[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xB3; SFR Page = All Pages
Bit
Name
P5[7:0] Port 5 Data.
Sets the Port latch logic
Description
Write
0: Set output latch to logic 0: P5.n Port pin is logic
LOW. LOW.
1: Set output latch to logic 1: P5.n Port pin is logic
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
190
Rev. 0.2
C8051F70x/71x
SFR Definition 26.31. P5MDIN: Port 5 Input Mode
Bit
7
6
5
4
3
2
1
0
P5MDIN[7:0]
R/W
Name
Type
Reset
1
1
1
1
1
1
1
1
SFR Address = 0xF6; SFR Page = F
Bit
Name
Function
7:0
P5MDIN[7:0] Analog Configuration Bits for P5.7–P5.0 (respectively).
Port pins configured for analog mode have their weak pullup, digital driver, and
digital receiver disabled.
0: Corresponding P5.n pin is configured for analog mode.
1: Corresponding P5.n pin is not configured for analog mode.
SFR Definition 26.32. P5MDOUT: Port 5 Output Mode
Bit
7
6
5
4
3
2
1
0
P5MDOUT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x9B; SFR Page = F
Bit Name
Function
7:0 P5MDOUT[7:0] Output Configuration Bits for P5.7–P5.0 (respectively).
These bits are ignored if the corresponding bit in register P5MDIN is logic 0.
0: Corresponding P5.n Output is open-drain.
1: Corresponding P5.n Output is push-pull.
Rev. 0.2
191
C8051F70x/71x
SFR Definition 26.33. P5DRV: Port 5 Drive Strength
Bit
7
6
5
4
3
2
1
0
P5DRV[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFE; SFR Page = F
Bit
Name
Function
7:0
P5DRV[7:0] Drive Strength Configuration Bits for P5.7-P5.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P5.n Output has low output drive strength.
1: Corresponding P5.n Output has high output drive strength.
SFR Definition 26.34. P6: Port 6
Bit
7
6
5
4
3
2
1
0
P6[5:0]
R/W
Name
Type
Reset
R
0
R
0
1
1
1
1
1
1
SFR Address = 0xB2; SFR Page = All Pages
Bit
7:6
5:0
Name
Unused Unused. Read = 00b; Write = Don’t Care
P6[5:0] Port 6 Data. 0: Set output latch to logic 0: P6.n Port pin is logic
LOW. LOW.
Description
Write
Read
Sets the Port latch logic
1: Set output latch to logic 1: P6.n Port pin is logic
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
192
Rev. 0.2
C8051F70x/71x
SFR Definition 26.35. P6MDOUT: Port 6 Output Mode
Bit
7
6
5
4
3
2
1
0
P6MDOUT[5:0]
R/W
Name
Type
Reset
R
0
R
0
0
0
0
0
0
0
SFR Address = 0x9C; SFR Page = F
Bit
Name
Function
7:6
Unused
Unused. Read = 00b; Write = Don’t Care
5:0 P6MDOUT[5:0] Output Configuration Bits for P6.5–P6.0 (respectively).
These bits are ignored if the corresponding bit in register P6MDIN is logic 0.
0: Corresponding P6.n Output is open-drain.
1: Corresponding P6.n Output is push-pull.
SFR Definition 26.36. P6DRV: Port 6 Drive Strength
Bit
7
6
5
4
3
2
1
0
P6DRV[5:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xC1; SFR Page = F
Bit
7:6
5:0
Name
Function
Unused
Unused. Read = 00b; Write = Don’t Care
P6DRV[5:0] Drive Strength Configuration Bits for P6.5-P6.0 (respectively).
Configures digital I/O Port cells to high or low output drive strength.
0: Corresponding P6.n Output has low output drive strength.
1: Corresponding P6.n Output has high output drive strength.
Rev. 0.2
193
C8051F70x/71x
27. Cyclic Redundancy Check Unit (CRC0)
C8051F70x/71x devices include a cyclic redundancy check unit (CRC0) that can perform a CRC using a
16-bit or 32-bit polynomial. CRC0 accepts a stream of 8-bit data written to the CRC0IN register. CRC0
posts the 16-bit or 32-bit result to an internal register. The internal result register may be accessed indi-
rectly using the CRC0PNT bits and CRC0DAT register, as shown in Figure 27.1. CRC0 also has a bit
reverse register for quick data manipulation.
8
8
Automatic CRC
Controller
Flash
Memory
CRC0IN
CRC0AUTO
CRC0CNT
CRC0SEL
CRC0INIT
CRC0VAL
CRC0PNT1
CRC0PNT0
CRC Engine
32
RESULT
CRC0FLIP
Write
8
8
8
8
4 to 1 MUX
8
CRC0DAT
CRC0FLIP
Read
Figure 27.1. CRC0 Block Diagram
194
Rev. 0.2
C8051F70x/71x
27.1. 16-bit CRC Algorithm
The C8051F70x/71x CRC unit calculates the 16-bit CRC MSB-first, using a poly of 0x1021. The following
describes the 16-bit CRC algorithm performed by the hardware:
1. XOR the most-significant byte of the current CRC result with the input byte. If this is the first iteration of
the CRC unit, the current CRC result will be the set initial value (0x0000 or 0xFFFF).
2. If the MSB of the CRC result is set, left-shift the CRC result, and then XOR the CRC result with the
polynomial (0x1021).
3. If the MSB of the CRC result is not set, left-shift the CRC result.
4. Repeat at Step 2 for the number of input bits (8).
For example, the 16-bit C8051F70x/71x CRC algorithm can be described by the following code:
unsigned short UpdateCRC (unsigned short CRC_acc, unsigned char CRC_input){
unsigned char i;
// loop counter
#define POLY 0x1021
// Create the CRC "dividend" for polynomial arithmetic (binary arithmetic
// with no carries)
CRC_acc = CRC_acc ^ (CRC_input << 8);
// "Divide" the poly into the dividend using CRC XOR subtraction
// CRC_acc holds the "remainder" of each divide
// Only complete this division for 8 bits since input is 1 byte
for (i = 0; i < 8; i++)
{
// Check if the MSB is set (if MSB is 1, then the POLY can "divide"
// into the "dividend")
if ((CRC_acc & 0x8000) == 0x8000)
{
// if so, shift the CRC value, and XOR "subtract" the poly
CRC_acc = CRC_acc << 1;
CRC_acc ^= POLY;
}
else
{
// if not, just shift the CRC value
CRC_acc = CRC_acc << 1;
}
}
return CRC_acc; // Return the final remainder (CRC value)
}
Table 27.1 lists example input values and the associated outputs using the 16-bit C8051F70x/71x CRC
algorithm (an initial value of 0xFFFF is used):
Table 27.1. Example 16-bit CRC Outputs
Input
Output
0x63
0xAA, 0xBB, 0xCC
0x00, 0x00, 0xAA, 0xBB, 0xCC
0xBD35
0x6CF6
0xB166
Rev. 0.2
195
C8051F70x/71x
27.2. 32-bit CRC Algorithm
The C8051F70x/71x CRC unit calculates the 32-bit CRC using a poly of 0x04C11DB7. The CRC-32 algo-
rithm is "reflected", meaning that all of the input bytes and the final 32-bit output are bit-reversed in the pro-
cessing engine. The following is a description of a simplified CRC algorithm that produces results identical
to the hardware:
1. XOR the least-significant byte of the current CRC result with the input byte. If this is the first iteration of
the CRC unit, the current CRC result will be the set initial value (0x00000000 or 0xFFFFFFFF).
2. Right-shift the CRC result.
3. If the LSB of the CRC result is set, XOR the CRC result with the reflected polynomial (0xEDB88320).
4. Repeat at Step 2 for the number of input bits (8).
For example, the 32-bit C8051F70x/71x CRC algorithm can be described by the following code:
unsigned long UpdateCRC (unsigned long CRC_acc, unsigned char CRC_input){
unsigned char i; // loop counter
#define POLY 0xEDB88320 // bit-reversed version of the poly 0x04C11DB7
// Create the CRC "dividend" for polynomial arithmetic (binary arithmetic
// with no carries)
CRC_acc = CRC_acc ^ CRC_input;
// "Divide" the poly into the dividend using CRC XOR subtraction
// CRC_acc holds the "remainder" of each divide
// Only complete this division for 8 bits since input is 1 byte
for (i = 0; i < 8; i++)
{
// Check if the MSB is set (if MSB is 1, then the POLY can "divide"
// into the "dividend")
if ((CRC_acc & 0x00000001) == 0x00000001)
{
// if so, shift the CRC value, and XOR "subtract" the poly
CRC_acc = CRC_acc >> 1;
CRC_acc ^= POLY;
}
else
{
// if not, just shift the CRC value
CRC_acc = CRC_acc >> 1;
}
}
return CRC_acc; // Return the final remainder (CRC value)
}
Table 27.2 lists example input values and the associated outputs using the 32-bit C8051F70x/71x CRC
algorithm (an initial value of 0xFFFFFFFF is used):
Table 27.2. Example 32-bit CRC Outputs
Input
Output
0x63
0xAA, 0xBB, 0xCC
0x00, 0x00, 0xAA, 0xBB, 0xCC
0xF9462090
0x41B207B3
0x78D129BC
196
Rev. 0.2
C8051F70x/71x
27.3. Preparing for a CRC Calculation
To prepare CRC0 for a CRC calculation, software should select the desired polynomial and set the initial
value of the result. Two polynomials are available: 0x1021 (16-bit) and 0x04C11DB7 (32-bit). The CRC0
result may be initialized to one of two values: 0x00000000 or 0xFFFFFFFF. The following steps can be
used to initialize CRC0.
1. Select a polynomial (Set CRC0SEL to 0 for 32-bit or 1 for 16-bit).
2. Select the initial result value (Set CRC0VAL to 0 for 0x00000000 or 1 for 0xFFFFFFFF).
3. Set the result to its initial value (Write 1 to CRC0INIT).
27.4. Performing a CRC Calculation
Once CRC0 is initialized, the input data stream is sequentially written to CRC0IN, one byte at a time. The
CRC0 result is automatically updated after each byte is written. The CRC engine may also be configured to
automatically perform a CRC on one or more Flash sectors. The following steps can be used to automati-
cally perform a CRC on Flash memory.
1. Prepare CRC0 for a CRC calculation as shown above.
2. Write the index of the starting page to CRC0AUTO.
3. Set the AUTOEN bit in CRC0AUTO.
4. Write the number of Flash sectors to perform in the CRC calculation to CRC0CNT.
Note: Each Flash sector is 512 bytes.
5. Write any value to CRC0CN (or OR its contents with 0x00) to initiate the CRC calculation. The CPU will
not execute code any additional code until the CRC operation completes.
6. Clear the AUTOEN bit in CRC0AUTO.
7. Read the CRC result using the procedure below.
27.5. Accessing the CRC0 Result
The internal CRC0 result is 32-bits (CRC0SEL = 0b) or 16-bits (CRC0SEL = 1b). The CRC0PNT bits
select the byte that is targeted by read and write operations on CRC0DAT and increment after each read or
write. The calculation result will remain in the internal CR0 result register until it is set, overwritten, or addi-
tional data is written to CRC0IN.
Rev. 0.2
197
C8051F70x/71x
SFR Definition 27.1. CRC0CN: CRC0 Control
Bit
7
6
5
4
3
2
1
0
CRC0SEL CRC0INIT CRC0VAL
CRC0PNT[1:0]
R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0x91; SFR Page = F
Bit
Name
Function
7:5
Unused
Unused.
Read = 000b; Write = Don’t Care.
4
CRC0SEL
CRC0 Polynomial Select Bit.
This bit selects the CRC0 polynomial and result length (32-bit or 16-bit).
0: CRC0 uses the 32-bit polynomial 0x04C11DB7 for calculating the CRC result.
1: CRC0 uses the 16-bit polynomial 0x1021 for calculating the CRC result.
3
2
CRC0INIT
CRC0VAL
CRC0 Result Initialization Bit.
Writing a 1 to this bit initializes the entire CRC result based on CRC0VAL.
CRC0 Set Value Initialization Bit.
This bit selects the set value of the CRC result.
0: CRC result is set to 0x00000000 on write of 1 to CRC0INIT.
1: CRC result is set to 0xFFFFFFFF on write of 1 to CRC0INIT.
1:0 CRC0PNT[1:0] CRC0 Result Pointer.
Specifies the byte of the CRC result to be read/written on the next access to
CRC0DAT. The value of these bits will auto-increment upon each read or write.
For CRC0SEL = 0:
00: CRC0DAT accesses bits 7–0 of the 32-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 32-bit CRC result.
10: CRC0DAT accesses bits 23–16 of the 32-bit CRC result.
11: CRC0DAT accesses bits 31–24 of the 32-bit CRC result.
For CRC0SEL = 1:
00: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
10: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
11: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
198
Rev. 0.2
C8051F70x/71x
SFR Definition 27.2. CRC0IN: CRC Data Input
Bit
7
6
5
4
3
2
1
0
CRC0IN[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x94; SFR Page = F
Bit Name
7:0 CRC0IN[7:0] CRC0 Data Input.
Function
Each write to CRC0IN results in the written data being computed into the existing
CRC result according to the CRC algorithm described in Section 27.1
SFR Definition 27.3. CRC0DATA: CRC Data Output
Bit
7
6
5
4
3
2
1
0
CRC0DAT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xD9; SFR Page = F
Bit Name
7:0 CRC0DAT[7:0] CRC0 Data Output.
Function
Each read or write performed on CRC0DAT targets the CRC result bits pointed to
by the CRC0 Result Pointer (CRC0PNT bits in CRC0CN).
Rev. 0.2
199
C8051F70x/71x
SFR Definition 27.4. CRC0AUTO: CRC Automatic Control
Bit
7
6
5
4
3
2
1
0
AUTOEN CRCCPT Reserved
CRC0ST[4:0]
Name
Type
Reset
R/W
0
1
0
0
0
0
0
0
SFR Address = 0x96; SFR Page = F
Bit
Name
Function
7
AUTOEN
Automatic CRC Calculation Enable.
When AUTOEN is set to 1, any write to CRC0CN will initiate an automatic CRC
starting at Flash sector CRC0ST and continuing for CRC0CNT sectors.
6
5
CRCCPT
Reserved
Automatic CRC Calculation Complete.
Set to 0 when a CRC calculation is in progress. Code execution is stopped during
a CRC calculation, therefore reads from firmware will always return 1.
Reserved. Must write 0.
4:0 CRC0ST[4:0] Automatic CRC Calculation Starting Flash Sector.
These bits specify the Flash sector to start the automatic CRC calculation. The
starting address of the first Flash sector included in the automatic CRC calculation
is CRC0ST x 512.
SFR Definition 27.5. CRC0CNT: CRC Automatic Flash Sector Count
Bit
7
6
5
4
3
2
1
0
CRC0CNT[5:0]
R/W
Name
Type
Reset
R
0
R
0
0
0
0
0
0
0
SFR Address = 0x97; SFR Page = F
Bit
Name
Function
7:6
Unused
Unused. Read = 00b; Write = Don’t Care.
5:0 CRC0CNT[5:0] Automatic CRC Calculation Flash Sector Count.
These bits specify the number of Flash sectors to include when performing an
automatic CRC calculation. The base address of the last flash sector included in
the automatic CRC calculation is equal to (CRC0ST + CRC0CNT) x 512.
27.6. CRC0 Bit Reverse Feature
CRC0 includes hardware to reverse the bit order of each bit in a byte as shown in Figure 27.1. Each byte
of data written to CRC0FLIP is read back bit reversed. For example, if 0xC0 is written to CRC0FLIP, the
data read back is 0x03. Bit reversal is a useful mathematical function used in algorithms such as the FFT.
200
Rev. 0.2
C8051F70x/71x
SFR Definition 27.6. CRC0FLIP: CRC Bit Flip
Bit
7
6
5
4
3
2
1
0
CRC0FLIP[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x95; SFR Page = F
Bit Name
7:0 CRC0FLIP[7:0] CRC0 Bit Flip.
Function
Any byte written to CRC0FLIP is read back in a bit-reversed order, i.e. the written
LSB becomes the MSB. For example:
If 0xC0 is written to CRC0FLIP, the data read back will be 0x03.
If 0x05 is written to CRC0FLIP, the data read back will be 0xA0.
Rev. 0.2
201
C8051F70x/71x
28. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
2
Management Bus Specification, version 1.1, and compatible with the I C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or
slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple mas-
ters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization,
arbitration logic, and START/STOP control and generation. The SMBus peripheral can be fully driven by
software (i.e., software accepts/rejects slave addresses, and generates ACKs), or hardware slave address
recognition and automatic ACK generation can be enabled to minimize software overhead. A block dia-
gram of the SMBus peripheral and the associated SFRs is shown in Figure 28.1.
SMB0CN
SMB0CF
M T S S A A A S
E
I
B E S S S S
A X T T C R C
S M A O K B K
I
N N U X M M M M
S H S T B B B B
T O
E D
R E
R L
Q O
S
M
B
Y H T F C C
O O T S S
L E E 1 0
D
T
00
01
10
11
T0 Overflow
T1 Overflow
TMR2H Overflow
TMR2L Overflow
SCL
SMBUS CONTROL LOGIC
Arbitration
FILTER
Interrupt
Request
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
SCL
Control
C
R
O
S
S
B
A
R
N
Hardware Slave Address Recognition
Hardware ACK Generation
Port I/O
Data Path
SDA
Control
IRQ Generation
Control
SMB0DAT
7 6 5 4 3 2 1 0
SDA
FILTER
S S S S S S S G S S S S S S S E
L L L L L L L C L L L L L L L H
V V V V V V V
6 5 4 3 2 1 0
V V V V V V V A
M M M M M M M C
6 5 4 3 2 1 0 K
SMB0ADR
SMB0ADM
N
Figure 28.1. SMBus Block Diagram
202
Rev. 0.2
C8051F70x/71x
28.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
2
1. The I C-Bus and How to Use It (including specifications), Philips Semiconductor.
2
2. The I C-Bus Specification—Version 2.0, Philips Semiconductor.
3. System Management Bus Specification—Version 1.1, SBS Implementers Forum.
28.2. SMBus Configuration
Figure 28.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-direc-
tional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when
the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
VDD = 5V
VDD = 3V
VDD = 5V
VDD = 3V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 28.2. Typical SMBus Configuration
28.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. It is not necessary to specify one device
as the Master in a system; any device who transmits a START and a slave address becomes the master
for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Bytes that are
received (by a master or slave) are acknowledged (ACK) with a low SDA during a high SCL (see
Figure 28.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowl-
edge), which is a high SDA during a high SCL.
The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
Rev. 0.2
203
C8051F70x/71x
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the trans-
action is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 28.3 illustrates a typical
SMBus transaction.
SCL
SDA
SLA6
SLA5-0
R/W
D7
D6-0
START
Slave Address + R/W
ACK
Data Byte
NACK
STOP
Figure 28.3. SMBus Transaction
28.3.1. Transmitter Vs. Receiver
On the SMBus communications interface, a device is the “transmitter” when it is sending an address or
data byte to another device on the bus. A device is a “receiver” when an address or data byte is being sent
to it from another device on the bus. The transmitter controls the SDA line during the address or data byte.
After each byte of address or data information is sent by the transmitter, the receiver sends an ACK or
NACK bit during the ACK phase of the transfer, during which time the receiver controls the SDA line.
28.3.2. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section “28.3.5. SCL High (SMBus Free) Timeout” on
page 205). In the event that two or more devices attempt to begin a transfer at the same time, an arbitra-
tion scheme is employed to force one master to give up the bus. The master devices continue transmitting
until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be
pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning
master continues its transmission without interruption; the losing master becomes a slave and receives the
rest of the transfer if addressed. This arbitration scheme is non-destructive: one device always wins, and
no data is lost.
28.3.3. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
28.3.4. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms after detecting the timeout condition.
204
Rev. 0.2
C8051F70x/71x
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout.
28.3.5. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods (as defined by the timer configured for the
SMBus clock source). If the SMBus is waiting to generate a Master START, the START will be generated
following this timeout. A clock source is required for free timeout detection, even in a slave-only implemen-
tation.
28.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting con-
trol for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
Byte-wise serial data transfers
Clock signal generation on SCL (Master Mode only) and SDA data synchronization
Timeout/bus error recognition, as defined by the SMB0CF configuration register
START/STOP timing, detection, and generation
Bus arbitration
Interrupt generation
Status information
Optional hardware recognition of slave address and automatic acknowledgement of address/data
SMBus interrupts are generated for each data byte or slave address that is transferred. When hardware
acknowledgement is disabled, the point at which the interrupt is generated depends on whether the hard-
ware is acting as a data transmitter or receiver. When a transmitter (i.e., sending address/data, receiving
an ACK), this interrupt is generated after the ACK cycle so that software may read the received ACK value;
when receiving data (i.e., receiving address/data, sending an ACK), this interrupt is generated before the
ACK cycle so that software may define the outgoing ACK value. If hardware acknowledgement is enabled,
these interrupts are always generated after the ACK cycle. See Section 28.5 for more details on transmis-
sion sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section 28.4.2;
Table 28.5 provides a quick SMB0CN decoding reference.
28.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
Rev. 0.2
205
C8051F70x/71x
Table 28.1. SMBus Clock Source Selection
SMBCS1 SMBCS0
SMBus Clock Source
0
0
1
1
0
1
0
1
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 28.1.The selected
clock source may be shared by other peripherals so long as the timer is left running at all times. For exam-
ple, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer configuration
is covered in Section “31. Timers” on page 245.
1
---------------------------------------------
THighMin = TLowMin
=
fClockSourceOverflow
Equation 28.1. Minimum SCL High and Low Times
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 28.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 28.2.
fClockSourceOverflow
---------------------------------------------
BitRate =
3
Equation 28.2. Typical SMBus Bit Rate
Figure 28.4 shows the typical SCL generation described by Equation 28.2. Notice that T
is typically
HIGH
twice as large as T
. The actual SCL output may vary due to other devices on the bus (SCL may be
LOW
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 28.1.
Timer Source
Overflows
SCL
TLow
THigh
SCL High Timeout
Figure 28.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high.
The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable
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after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 28.2 shows the min-
imum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically
necessary when SYSCLK is above 10 MHz.
Table 28.2. Minimum SDA Setup and Hold Times
EXTHOLD
Minimum SDA Setup Time
Minimum SDA Hold Time
T
– 4 system clocks
or
low
0
1
3 system clocks
12 system clocks
*
1 system clock + s/w delay
11 system clocks
Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. When using
software acknowledgement, the s/w delay occurs between the time SMB0DAT or
ACK is written and when SI is cleared. Note that if SI is cleared in the same write
that defines the outgoing ACK value, s/w delay is zero.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “28.3.4. SCL Low Timeout” on page 204). The SMBus interface will force Timer 3 to
reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine
should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 28.4).
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SFR Definition 28.1. SMB0CF: SMBus Clock/Configuration
Bit
7
6
5
4
3
2
1
0
ENSMB
INH
BUSY
EXTHOLD SMBTOE SMBFTE
SMBCS[1:0]
R/W
Name
Type
Reset
R/W
0
R/W
0
R
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0xC1; SFR Page = 0
Bit
Name
Function
7
ENSMB
SMBus Enable.
This bit enables the SMBus interface when set to 1. When enabled, the interface
constantly monitors the SDA and SCL pins.
6
INH
SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interrupt when slave
events occur. This effectively removes the SMBus slave from the bus. Master Mode
interrupts are not affected.
5
4
BUSY
SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to
logic 0 when a STOP or free-timeout is sensed.
EXTHOLD SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and hold times according to Table 28.2.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
3
SMBTOE SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces
Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low.
If Timer 3 is configured to Split Mode, only the High Byte of the timer is held in reload
while SCL is high. Timer 3 should be programmed to generate interrupts at 25 ms,
and the Timer 3 interrupt service routine should reset SMBus communication.
2
SMBFTE SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain
high for more than 10 SMBus clock source periods.
1:0 SMBCS[1:0] SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus
bit rate. The selected device should be configured according to Equation 28.1.
00: Timer 0 Overflow
01: Timer 1 Overflow
10: Timer 2 High Byte Overflow
11: Timer 2 Low Byte Overflow
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28.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 28.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER indicates whether a device is the master or slave during the current
transfer. TXMODE indicates whether the device is transmitting or receiving data for the current byte.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO are also used to generate START and STOP conditions when operating as a mas-
ter. Writing a 1 to STA will cause the SMBus interface to enter Master Mode and generate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a 1 to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condi-
tion. ARBLOST is cleared by hardware each time SI is cleared.
The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or
when an arbitration is lost; see Table 28.3 for more details.
Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
28.4.2.1. Software ACK Generation
When the EHACK bit in register SMB0ADM is cleared to 0, the firmware on the device must detect incom-
ing slave addresses and ACK or NACK the slave address and incoming data bytes. As a receiver, writing
the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value
received during the last ACK cycle. ACKRQ is set each time a byte is received, indicating that an outgoing
ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK
bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI.
SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will
remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be
ignored until the next START is detected.
28.4.2.2. Hardware ACK Generation
When the EHACK bit in register SMB0ADM is set to 1, automatic slave address recognition and ACK gen-
eration is enabled. More detail about automatic slave address recognition can be found in Section 28.4.3.
As a receiver, the value currently specified by the ACK bit will be automatically sent on the bus during the
ACK cycle of an incoming data byte. As a transmitter, reading the ACK bit indicates the value received on
the last ACK cycle. The ACKRQ bit is not used when hardware ACK generation is enabled. If a received
slave address is NACKed by hardware, further slave events will be ignored until the next START is
detected, and no interrupt will be generated.
Table 28.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 28.5 for SMBus sta-
tus decoding using the SMB0CN register.
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SFR Definition 28.2. SMB0CN: SMBus Control
Bit
7
6
5
4
3
2
1
0
MASTER TXMODE
STA
STO
ACKRQ ARBLOST
ACK
SI
Name
Type
Reset
R
0
R
0
R/W
0
R/W
0
R
0
R
0
R/W
0
R/W
0
SFR Address = 0xC0; SFR Page = All Pages; Bit-Addressable
Bit
Name
Description
Read
Write
7
MASTER SMBus Master/Slave
Indicator. This read-only bit
0: SMBus operating in
slave mode.
N/A
N/A
indicates when the SMBus is 1: SMBus operating in
operating as a master.
master mode.
6
5
4
TXMODE SMBus Transmit Mode
Indicator. This read-only bit
0: SMBus in Receiver
Mode.
indicates when the SMBus is 1: SMBus in Transmitter
operating as a transmitter.
Mode.
STA
STO
SMBus Start Flag.
0: No Start or repeated
Start detected.
1: Start or repeated Start
detected.
0: No Start generated.
1: When Configured as a
Master, initiates a START
or repeated START.
SMBus Stop Flag.
0: No Stop condition
detected.
0: No STOP condition is
transmitted.
1: Stop condition detected 1: When configured as a
(if in Slave Mode) or pend- Master, causes a STOP
ing (if in Master Mode).
condition to be transmit-
ted after the next ACK
cycle.
Cleared by Hardware.
3
2
1
0
ACKRQ SMBus Acknowledge
0: No Ack requested
1: ACK requested
N/A
N/A
Request.
ARBLOST SMBus Arbitration Lost
0: No arbitration error.
1: Arbitration Lost
Indicator.
ACK
SI
SMBus Acknowledge.
0: NACK received.
1: ACK received.
0: Send NACK
1: Send ACK
SMBus Interrupt Flag.
This bit is set by hardware
under the conditions listed in
Table 15.3. SI must be cleared
by software. While SI is set,
SCL is held low and the
SMBus is stalled.
0: No interrupt pending
1: Interrupt Pending
0: Clear interrupt, and initi-
ate next state machine
event.
1: Force interrupt.
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Table 28.3. Sources for Hardware Changes to SMB0CN
Bit
Set by Hardware When:
A START is generated.
Cleared by Hardware When:
A STOP is generated.
Arbitration is lost.
A START is detected.
Arbitration is lost.
MASTER
START is generated.
SMB0DAT is written before the start of an
SMBus frame.
TXMODE
SMB0DAT is not written before the
start of an SMBus frame.
A START followed by an address byte is
received.
A STOP is detected while addressed as a
slave.
Must be cleared by software.
STA
STO
A pending STOP is generated.
Arbitration is lost due to a detected STOP.
A byte has been received and an ACK
response value is needed (only when
hardware ACK is not enabled).
A repeated START is detected as a
MASTER when STA is low (unwanted
repeated START).
After each ACK cycle.
Each time SI is cleared.
ACKRQ
SCL is sensed low while attempting to
generate a STOP or repeated START
condition.
ARBLOST
ACK
SDA is sensed low while transmitting a 1
(excluding ACK bits).
The incoming ACK value is low
(ACKNOWLEDGE).
The incoming ACK value is high
(NOT ACKNOWLEDGE).
Must be cleared by software.
A START has been generated.
Lost arbitration.
A byte has been transmitted and an
ACK/NACK received.
SI
A byte has been received.
A START or repeated START followed by a
slave address + R/W has been received.
A STOP has been received.
28.4.3. Hardware Slave Address Recognition
The SMBus hardware has the capability to automatically recognize incoming slave addresses and send an
ACK without software intervention. Automatic slave address recognition is enabled by setting the EHACK
bit in register SMB0ADM to 1. This will enable both automatic slave address recognition and automatic
hardware ACK generation for received bytes (as a master or slave). More detail on automatic hardware
ACK generation can be found in Section 28.4.2.2.
The registers used to define which address(es) are recognized by the hardware are the SMBus Slave
Address register (SFR Definition 28.3) and the SMBus Slave Address Mask register (SFR Definition 28.4).
A single address or range of addresses (including the General Call Address 0x00) can be specified using
these two registers. The most-significant seven bits of the two registers are used to define which
addresses will be ACKed. A 1 in bit positions of the slave address mask SLVM[6:0] enable a comparison
between the received slave address and the hardware’s slave address SLV[6:0] for those bits. A 0 in a bit
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of the slave address mask means that bit will be treated as a “don’t care” for comparison purposes. In this
case, either a 1 or a 0 value are acceptable on the incoming slave address. Additionally, if the GC bit in
register SMB0ADR is set to 1, hardware will recognize the General Call Address (0x00). Table 28.4 shows
some example parameter settings and the slave addresses that will be recognized by hardware under
those conditions.
Table 28.4. Hardware Address Recognition Examples (EHACK = 1)
Hardware Slave Address Slave Address Mask
GC bit Slave Addresses Recognized by
Hardware
SLV[6:0]
SLVM[6:0]
0x34
0x34
0x34
0x34
0x70
0x7F
0x7F
0x7E
0x7E
0x73
0
1
0
1
0
0x34
0x34, 0x00 (General Call)
0x34, 0x35
0x34, 0x35, 0x00 (General Call)
0x70, 0x74, 0x78, 0x7C
SFR Definition 28.3. SMB0ADR: SMBus Slave Address
Bit
7
6
5
4
3
2
1
0
SLV[6:0]
GC
Name
Type
Reset
R/W
0
R/W
0
0
0
0
0
0
0
SFR Address = 0xBA; SFR Page = F
Bit
Name
Function
7:1
SLV[6:0]
SMBus Hardware Slave Address.
Defines the SMBus Slave Address(es) for automatic hardware acknowledgement.
Only address bits which have a 1 in the corresponding bit position in SLVM[6:0]
are checked against the incoming address. This allows multiple addresses to be
recognized.
0
GC
General Call Address Enable.
When hardware address recognition is enabled (EHACK = 1), this bit will deter-
mine whether the General Call Address (0x00) is also recognized by hardware.
0: General Call Address is ignored.
1: General Call Address is recognized.
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SFR Definition 28.4. SMB0ADM: SMBus Slave Address Mask
Bit
7
6
5
4
3
2
1
0
SLVM[6:0]
EHACK
Name
Type
Reset
R/W
1
R/W
0
1
1
1
1
1
1
SFR Address = 0xBB; SFR Page = F
Bit
Name
Function
7:1
SLVM[6:0]
SMBus Slave Address Mask.
Defines which bits of register SMB0ADR are compared with an incoming address
byte, and which bits are ignored. Any bit set to 1 in SLVM[6:0] enables compari-
sons with the corresponding bit in SLV[6:0]. Bits set to 0 are ignored (can be either
0 or 1 in the incoming address).
0
EHACK
Hardware Acknowledge Enable.
Enables hardware acknowledgement of slave address and received data bytes.
0: Firmware must manually acknowledge all incoming address and data bytes.
1: Automatic Slave Address Recognition and Hardware Acknowledge is Enabled.
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28.4.4. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbi-
tration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 28.5. SMB0DAT: SMBus Data
Bit
7
6
5
4
3
2
1
0
SMB0DAT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xC2; SFR Page = 0
Bit Name
7:0 SMB0DAT[7:0] SMBus Data.
Function
The SMB0DAT register contains a byte of data to be transmitted on the SMBus
serial interface or a byte that has just been received on the SMBus serial interface.
The CPU can read from or write to this register whenever the SI serial interrupt flag
(SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long
as the SI flag is set. When the SI flag is not set, the system may be in the process
of shifting data in/out and the CPU should not attempt to access this register.
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28.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames. The position of the ACK interrupt when operating as a receiver depends on
whether hardware ACK generation is enabled. As a receiver, the interrupt for an ACK occurs before the
ACK with hardware ACK generation disabled, and after the ACK when hardware ACK generation is
enabled. As a transmitter, interrupts occur after the ACK, regardless of whether hardware ACK generation
is enabled or not.
28.5.1. Write Sequence (Master)
During a write sequence, an SMBus master writes data to a slave device. The master in this transfer will be
a transmitter during the address byte, and a transmitter during all data bytes. The SMBus interface gener-
ates the START condition and transmits the first byte containing the address of the target slave and the
data direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then trans-
mits one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by
the slave. The transfer is ended when the STO bit is set and a STOP is generated. The interface will switch
to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt. Figure 28.5
shows a typical master write sequence. Two transmit data bytes are shown, though any number of bytes
may be transmitted. Notice that all of the “data byte transferred” interrupts occur after the ACK cycle in this
mode, regardless of whether hardware ACK generation is enabled.
Interrupts with Hardware ACK Enabled (EHACK = 1)
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupts with Hardware ACK Disabled (EHACK = 0)
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
Transmitted by
SLA = Slave Address
SMBus Interface
Figure 28.5. Typical Master Write Sequence
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28.5.2. Read Sequence (Master)
During a read sequence, an SMBus master reads data from a slave device. The master in this transfer will
be a transmitter during the address byte, and a receiver during all data bytes. The SMBus interface gener-
ates the START condition and transmits the first byte containing the address of the target slave and the
data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then
received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more
bytes of serial data.
If hardware ACK generation is disabled, the ACKRQ is set to 1 and an interrupt is generated after each
received byte. Software must write the ACK bit at that time to ACK or NACK the received byte.
With hardware ACK generation enabled, the SMBus hardware will automatically generate the ACK/NACK,
and then post the interrupt. It is important to note that the appropriate ACK or NACK value should be
set up by the software prior to receiving the byte when hardware ACK generation is enabled.
Writing a 1 to the ACK bit generates an ACK; writing a 0 generates a NACK. Software should write a 0 to
the ACK bit for the last data transfer, to transmit a NACK. The interface exits Master Receiver Mode after
the STO bit is set and a STOP is generated. The interface will switch to Master Transmitter Mode if
SMB0DAT is written while an active Master Receiver. Figure 28.6 shows a typical master read sequence.
Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data
byte transferred’ interrupts occur at different places in the sequence, depending on whether hardware ACK
generation is enabled. The interrupt occurs before the ACK with hardware ACK generation disabled, and
after the ACK when hardware ACK generation is enabled.
Interrupts with Hardware ACK Enabled (EHACK = 1)
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupts with Hardware ACK Disabled (EHACK = 0)
S = START
P = STOP
A = ACK
Received by SMBus
Interface
N = NACK
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 28.6. Typical Master Read Sequence
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28.5.3. Write Sequence (Slave)
During a write sequence, an SMBus master writes data to a slave device. The slave in this transfer will be
a receiver during the address byte, and a receiver during all data bytes. When slave events are enabled
(INH = 0), the interface enters Slave Receiver Mode when a START followed by a slave address and direc-
tion bit (WRITE in this case) is received. If hardware ACK generation is disabled, upon entering Slave
Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The software must respond to the
received slave address with an ACK, or ignore the received slave address with a NACK. If hardware ACK
generation is enabled, the hardware will apply the ACK for a slave address which matches the criteria set
up by SMB0ADR and SMB0ADM. The interrupt will occur after the ACK cycle.
If the received slave address is ignored (by software or hardware), slave interrupts will be inhibited until the
next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received.
If hardware ACK generation is disabled, the ACKRQ is set to 1 and an interrupt is generated after each
received byte. Software must write the ACK bit at that time to ACK or NACK the received byte.
With hardware ACK generation enabled, the SMBus hardware will automatically generate the ACK/NACK,
and then post the interrupt. It is important to note that the appropriate ACK or NACK value should be
set up by the software prior to receiving the byte when hardware ACK generation is enabled.
The interface exits Slave Receiver Mode after receiving a STOP. The interface will switch to Slave Trans-
mitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 28.7 shows a typical slave write
sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that
the ‘data byte transferred’ interrupts occur at different places in the sequence, depending on whether hard-
ware ACK generation is enabled. The interrupt occurs before the ACK with hardware ACK generation dis-
abled, and after the ACK when hardware ACK generation is enabled.
Interrupts with Hardware ACK Enabled (EHACK = 1)
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupts with Hardware ACK Disabled (EHACK = 0)
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 28.7. Typical Slave Write Sequence
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28.5.4. Read Sequence (Slave)
During a read sequence, an SMBus master reads data from a slave device. The slave in this transfer will
be a receiver during the address byte, and a transmitter during all data bytes. When slave events are
enabled (INH = 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START
followed by a slave address and direction bit (READ in this case) is received. If hardware ACK generation
is disabled, upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The
software must respond to the received slave address with an ACK, or ignore the received slave address
with a NACK. If hardware ACK generation is enabled, the hardware will apply the ACK for a slave address
which matches the criteria set up by SMB0ADR and SMB0ADM. The interrupt will occur after the ACK
cycle.
If the received slave address is ignored (by software or hardware), slave interrupts will be inhibited until the
next START is detected. If the received slave address is acknowledged, zero or more data bytes are trans-
mitted. If the received slave address is acknowledged, data should be written to SMB0DAT to be transmit-
ted. The interface enters slave transmitter mode, and transmits one or more bytes of data. After each byte
is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should
be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to
before SI is cleared (an error condition may be generated if SMB0DAT is written following a received
NACK while in slave transmitter mode). The interface exits slave transmitter mode after receiving a STOP.
The interface will switch to slave receiver mode if SMB0DAT is not written following a Slave Transmitter
interrupt. Figure 28.8 shows a typical slave read sequence. Two transmitted data bytes are shown, though
any number of bytes may be transmitted. Notice that all of the “data byte transferred” interrupts occur after
the ACK cycle in this mode, regardless of whether hardware ACK generation is enabled.
Interrupts with Hardware ACK Enabled (EHACK = 1)
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupts with Hardware ACK Disabled (EHACK = 0)
S = START
P = STOP
N = NACK
Received by SMBus
Interface
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 28.8. Typical Slave Read Sequence
28.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. The appropriate actions to
take in response to an SMBus event depend on whether hardware slave address recognition and ACK
generation is enabled or disabled. Table 28.5 describes the typical actions when hardware slave address
recognition and ACK generation is disabled. Table 28.6 describes the typical actions when hardware slave
address recognition and ACK generation is enabled. In the tables, STATUS VECTOR refers to the four
upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. The shown response options are only the typ-
ical responses; application-specific procedures are allowed as long as they conform to the SMBus specifi-
cation. Highlighted responses are allowed by hardware but do not conform to the SMBus specification.
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Table 28.5. SMBus Status Decoding With Hardware ACK Generation Disabled
(EHACK = 0)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
A master START was gener- Load slave address + R/W into
0
0
X
1100
1110
0
0
0
0
X
ated.
SMB0DAT.
A master data or address byte Set STA to restart transfer.
1
0
0
1
X
X
1110
—
0 was transmitted; NACK
received.
Abort transfer.
Load next data byte into
SMB0DAT.
0
0
X
1100
End transfer with STOP.
0
1
1
1
X
X
—
—
1100
A master data or address byte End transfer with STOP and start
0
0
1 was transmitted; ACK
received.
another transfer.
Send repeated START.
1
0
0
0
X
X
1110
1000
Switch to Master Receiver Mode
(clear SI without writing new data
to SMB0DAT).
Acknowledge received byte;
Read SMB0DAT.
0
0
1
0
1
1
1
0
0
1000
—
Send NACK to indicate last byte,
and send STOP.
Send NACK to indicate last byte,
and send STOP followed by
START.
1110
Send ACK followed by repeated
START.
1
1
0
0
0
0
1
0
1
1110
1110
1100
A master data byte was
0 X
1000
1
received; ACK requested.
Send NACK to indicate last byte,
and send repeated START.
Send ACK and switch to Master
Transmitter Mode (write to
SMB0DAT before clearing SI).
Send NACK and switch to Mas-
ter Transmitter Mode (write to
SMB0DAT before clearing SI).
0
0
0
1100
Rev. 0.2
219
C8051F70x/71x
Table 28.5. SMBus Status Decoding With Hardware ACK Generation Disabled
(EHACK = 0) (Continued)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
A slave byte was transmitted; No action required (expecting
0
0
0
0
0
0
0
0
X
X
X
X
0001
0100
0001
—
0
0
0
0
0
1
0
1
NACK received.
A slave byte was transmitted; Load SMB0DAT with next data
ACK received. byte to transmit.
A Slave byte was transmitted; No action required (expecting
STOP condition).
0100
0101
X
error detected.
Master to end transfer).
An illegal STOP or bus error
0
1
X
0
X was detected while a Slave
Transmission was in progress.
Clear STO.
If Write, Acknowledge received
address
0
0
0
0
1
1
0000
0100
A slave address + R/W was
X
If Read, Load SMB0DAT with
data byte; ACK received address
received; ACK requested.
NACK received address.
0
0
0
0
0
1
—
If Write, Acknowledge received
address
0000
0010
If Read, Load SMB0DAT with
data byte; ACK received address
0
0
1
0100
Lost arbitration as master;
X slave address + R/W received;
ACK requested.
1
1
NACK received address.
0
1
0
0
0
0
—
Reschedule failed transfer;
NACK received address.
1110
A STOP was detected while
0
0
X
—
0
1
0
1
X addressed as a Slave Trans- Clear STO.
mitter or Slave Receiver.
0001
0000
Lost arbitration while attempt- No action required (transfer
X
0
0
0
0
0
0
0
1
0
—
0000
—
ing a STOP.
complete/aborted).
Acknowledge received byte;
Read SMB0DAT.
A slave byte was received;
ACK requested.
1
0
X
NACK received byte.
220
Rev. 0.2
C8051F70x/71x
Table 28.5. SMBus Status Decoding With Hardware ACK Generation Disabled
(EHACK = 0) (Continued)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
Abort failed transfer.
0
1
0
1
0
1
0
0
0
0
0
0
X
X
X
X
0
—
1110
—
Lost arbitration while attempt-
ing a repeated START.
0010
0001
0000
0
0
1
1
1
1
X
X
X
Reschedule failed transfer.
Abort failed transfer.
Lost arbitration due to a
detected STOP.
Reschedule failed transfer.
Abort failed transfer.
1110
—
Lost arbitration while transmit-
ting a data byte as master.
Reschedule failed transfer.
0
1110
Table 28.6. SMBus Status Decoding With Hardware ACK Generation Enabled
(EHACK = 1)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
A master START was gener- Load slave address + R/W into
0
0
X
1100
1110
0
0
0
0
X
ated.
SMB0DAT.
A master data or address byte Set STA to restart transfer.
1
0
0
1
X
X
1110
—
0 was transmitted; NACK
received.
Abort transfer.
Load next data byte into
SMB0DAT.
0
0
X
1100
End transfer with STOP.
0
1
1
1
X
X
—
—
1100
End transfer with STOP and start
another transfer.
A master data or address byte
1 was transmitted; ACK
received.
0
0
Send repeated START.
1
0
0
0
X
1
1110
1000
Switch to Master Receiver Mode
(clear SI without writing new data
to SMB0DAT). Set ACK for initial
data byte.
Rev. 0.2
221
C8051F70x/71x
Table 28.6. SMBus Status Decoding With Hardware ACK Generation Enabled
(EHACK = 1) (Continued)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
Set ACK for next data byte;
Read SMB0DAT.
0
0
0
0
1
0
1000
1000
Set NACK to indicate next data
byte as the last data byte;
Read SMB0DAT.
A master data byte was
received; ACK sent.
0
0
1
Initiate repeated START.
1
0
0
0
0
1110
1100
Switch to Master Transmitter
Mode (write to SMB0DAT before
clearing SI).
X
1000
Read SMB0DAT; send STOP.
0
1
1
1
0
0
—
Read SMB0DAT; Send STOP
followed by START.
1110
A master data byte was
0
0
0 received; NACK sent (last
byte).
Initiate repeated START.
1
0
0
0
0
1110
1100
Switch to Master Transmitter
Mode (write to SMB0DAT before
clearing SI).
X
A slave byte was transmitted; No action required (expecting
0
0
0
0
0
0
0
0
X
X
X
X
0001
0100
0001
—
0
0
0
0
0
1
0
1
NACK received.
A slave byte was transmitted; Load SMB0DAT with next data
ACK received. byte to transmit.
A Slave byte was transmitted; No action required (expecting
STOP condition).
0100
0101
X
error detected.
Master to end transfer).
An illegal STOP or bus error
0
X
X was detected while a Slave
Transmission was in progress.
Clear STO.
222
Rev. 0.2
C8051F70x/71x
Table 28.6. SMBus Status Decoding With Hardware ACK Generation Enabled
(EHACK = 1) (Continued)
Values to
Write
Values Read
Current SMbus State
Typical Response Options
If Write, Set ACK for first data
byte.
0
0
0
0
0
0
0
0
1
X
1
0000
0100
0000
0100
A slave address + R/W was
received; ACK sent.
0
0
0
1
X
If Read, Load SMB0DAT with
data byte
0010
If Write, Set ACK for first data
byte.
Lost arbitration as master;
X slave address + R/W received; If Read, Load SMB0DAT with
X
ACK sent.
data byte
Reschedule failed transfer
1
0
0
0
X
X
1110
—
A STOP was detected while
0
0
0
1
X addressed as a Slave Trans- Clear STO.
mitter or Slave Receiver.
0001
0000
Lost arbitration while attempt- No action required (transfer
X
0
0
0
0
0
0
0
1
0
—
ing a STOP.
complete/aborted).
Set ACK for next data byte;
Read SMB0DAT.
0000
0000
0
0
X A slave byte was received.
Set NACK for next data byte;
Read SMB0DAT.
Abort failed transfer.
0
1
0
1
0
1
0
0
0
0
0
0
X
X
X
X
X
X
—
1110
—
Lost arbitration while attempt-
ing a repeated START.
0010
0001
0
0
1
1
X
Reschedule failed transfer.
Abort failed transfer.
Lost arbitration due to a
detected STOP.
X
Reschedule failed transfer.
Abort failed transfer.
1110
—
Lost arbitration while transmit-
ting a data byte as master.
0000
0
1
X
1110
Reschedule failed transfer.
Rev. 0.2
223
C8051F70x/71x
29. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports mul-
tiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional gen-
eral purpose port I/O pins can be used to select multiple slave devices in master mode.
SFR Bus
SPI0CKR
SPI0CFG
SPI0CN
Clock Divide
Logic
SYSCLK
SPI CONTROL LOGIC
SPI IRQ
Data Path
Control
Pin Interface
Control
MOSI
Tx Data
C
R
O
S
S
B
A
R
SPI0DAT
SCK
MISO
NSS
Transmit Data Buffer
Pin
Control
Logic
Port I/O
Shift Register
Rx Data
7 6 5 4 3 2 1 0
Receive Data Buffer
Read
SPI0DAT
Write
SPI0DAT
SFR Bus
Figure 29.1. SPI Block Diagram
224
Rev. 0.2
C8051F70x/71x
29.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
29.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
29.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
29.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
29.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is
disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select
signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-to-
point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is
enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a
master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple
master devices can be used on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an
output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration
should only be used when operating SPI0 as a master device.
See Figure 29.2, Figure 29.3, and Figure 29.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “26. Port Input/Output” on page 166 for general purpose
port I/O and crossbar information.
Rev. 0.2
225
C8051F70x/71x
29.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when
NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and
is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in
this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and
a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumstances. In multi-master systems, devices will
typically default to being slave devices while they are not acting as the system master device. In multi-mas-
ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 29.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 29.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 29.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
NSS
MISO
MOSI
SCK
GPIO
MISO
MOSI
SCK
Master
Device 1
Master
Device 2
GPIO
NSS
Figure 29.2. Multiple-Master Mode Connection Diagram
226
Rev. 0.2
C8051F70x/71x
Master
Device
Slave
Device
MISO
MOSI
SCK
MISO
MOSI
SCK
Figure 29.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection
Diagram
MISO
MOSI
SCK
MISO
MOSI
SCK
Master
Device
Slave
Device
NSS
NSS
GPIO
MISO
MOSI
SCK
Slave
Device
NSS
Figure 29.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection
Diagram
29.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig-
nal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift reg-
ister, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-
buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit
buffer will immediately be transferred into the shift register. When the shift register already contains data,
the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or
current) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. The NSS signal must
be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 29.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
Rev. 0.2
227
C8051F70x/71x
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and re-
enabling SPI0 with the SPIEN bit. Figure 29.3 shows a connection diagram between a slave device in 3-
wire slave mode and a master device.
29.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
All of the following bits must be cleared by software.
The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can
occur in all SPI0 modes.
The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when
the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to
SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0
modes.
The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master, and for
multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN
bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus.
The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a
transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new
byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The
data byte which caused the overrun is lost.
29.5. Serial Clock Phase and Polarity
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 29.5. For slave mode, the clock and
data relationships are shown in Figure 29.6 and Figure 29.7. CKPHA should be set to 0 on both the master
and slave SPI when communicating between two Silicon Labs C8051 devices.
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 29.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-
wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s
system clock.
228
Rev. 0.2
C8051F70x/71x
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (Must Remain High
in Multi-Master Mode)
Figure 29.5. Master Mode Data/Clock Timing
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
MOSI
MSB
MSB
Bit 6
Bit 6
Bit 5
Bit 5
Bit 4
Bit 4
Bit 3
Bit 3
Bit 2
Bit 2
Bit 1
Bit 1
Bit 0
Bit 0
MISO
NSS (4-Wire Mode)
Figure 29.6. Slave Mode Data/Clock Timing (CKPHA = 0)
Rev. 0.2
229
C8051F70x/71x
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=1)
MOSI
MSB
MSB
Bit 6
Bit 6
Bit 5
Bit 5
Bit 4
Bit 4
Bit 3
Bit 3
Bit 2
Bit 2
Bit 1
Bit 1
Bit 0
MISO
Bit 0
NSS (4-Wire Mode)
Figure 29.7. Slave Mode Data/Clock Timing (CKPHA = 1)
29.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
230
Rev. 0.2
C8051F70x/71x
SFR Definition 29.1. SPI0CFG: SPI0 Configuration
Bit
7
6
5
4
3
2
1
0
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
Name
Type
Reset
R
0
R/W
0
R/W
0
R/W
0
R
0
R
1
R
1
R
1
SFR Address = 0xA1; SFR Page = 0
Bit
Name
Function
7
SPIBSY
SPI Busy.
This bit is set to logic 1 when a SPI transfer is in progress (master or slave mode).
6
5
4
3
MSTEN
CKPHA
CKPOL
SLVSEL
Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
SPI0 Clock Phase.
0: Data centered on first edge of SCK period.
1: Data centered on second edge of SCK period.
*
*
SPI0 Clock Polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Slave Selected Flag.
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected
slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does
not indicate the instantaneous value at the NSS pin, but rather a de-glitched ver-
sion of the pin input.
2
1
NSSIN
SRMT
NSS Instantaneous Pin Input.
This bit mimics the instantaneous value that is present on the NSS port pin at the
time that the register is read. This input is not de-glitched.
Shift Register Empty (valid in slave mode only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift
register, and there is no new information available to read from the transmit buffer
or write to the receive buffer. It returns to logic 0 when a data byte is transferred to
the shift register from the transmit buffer or by a transition on SCK. SRMT = 1 when
in Master Mode.
0
RXBMT
Receive Buffer Empty (valid in slave mode only).
This bit will be set to logic 1 when the receive buffer has been read and contains no
new information. If there is new information available in the receive buffer that has
not been read, this bit will return to logic 0. RXBMT = 1 when in Master Mode.
Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is
sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device.
See Table 29.1 for timing parameters.
Rev. 0.2
231
C8051F70x/71x
SFR Definition 29.2. SPI0CN: SPI0 Control
Bit
7
6
5
4
3
2
1
0
SPIF
WCOL
MODF
RXOVRN
NSSMD[1:0]
R/W
TXBMT
SPIEN
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R
1
R/W
0
0
1
SFR Address = 0xF8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
SPIF
SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If SPI interrupts
are enabled, an interrupt will be generated. This bit is not automatically cleared by
hardware, and must be cleared by software.
6
5
4
WCOL
MODF
Write Collision Flag.
This bit is set to logic 1 if a write to SPI0DAT is attempted when TXBMT is 0. When
this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be
written. If SPI interrupts are enabled, an interrupt will be generated. This bit is not
automatically cleared by hardware, and must be cleared by software.
Mode Fault Flag.
This bit is set to logic 1 by hardware when a master mode collision is detected
(NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). If SPI interrupts are enabled, an
interrupt will be generated. This bit is not automatically cleared by hardware, and
must be cleared by software.
RXOVRN
Receive Overrun Flag (valid in slave mode only).
This bit is set to logic 1 by hardware when the receive buffer still holds unread data
from a previous transfer and the last bit of the current transfer is shifted into the
SPI0 shift register. If SPI interrupts are enabled, an interrupt will be generated. This
bit is not automatically cleared by hardware, and must be cleared by software.
3:2 NSSMD[1:0] Slave Select Mode.
Selects between the following NSS operation modes:
(See Section 29.2 and Section 29.3).
00: 3-Wire Slave or 3-Wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the
device and will assume the value of NSSMD0.
1
0
TXBMT
SPIEN
Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer.
When data in the transmit buffer is transferred to the SPI shift register, this bit will
be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer.
SPI0 Enable.
0: SPI disabled.
1: SPI enabled.
232
Rev. 0.2
C8051F70x/71x
SFR Definition 29.3. SPI0CKR: SPI0 Clock Rate
Bit
7
6
5
4
3
2
1
0
SCR[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA2; SFR Page = F
Bit
Name
Function
7:0
SCR[7:0]
SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is
configured for master mode operation. The SCK clock frequency is a divided ver-
sion of the system clock, and is given in the following equation, where SYSCLK is
the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR
register.
SYSCLK
2 SPI0CKR[7:0] + 1
----------------------------------------------------------
=
fSCK
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000
-------------------------
=
fSCK
2 4 + 1
fSCK = 200kHz
SFR Definition 29.4. SPI0DAT: SPI0 Data
Bit
7
6
5
4
3
2
1
0
SPI0DAT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xA3; SFR Page = 0
Bit Name
7:0 SPI0DAT[7:0] SPI0 Transmit and Receive Data.
Function
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to
SPI0DAT places the data into the transmit buffer and initiates a transfer when in
Master Mode. A read of SPI0DAT returns the contents of the receive buffer.
Rev. 0.2
233
C8051F70x/71x
SCK*
T
T
MCKL
MCKH
T
T
MIS
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 29.8. SPI Master Timing (CKPHA = 0)
SCK*
T
T
MCKL
MCKH
T
T
MIH
MIS
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 29.9. SPI Master Timing (CKPHA = 1)
234
Rev. 0.2
C8051F70x/71x
NSS
T
T
T
SE
CKL
SD
SCK*
T
CKH
T
T
SIH
SIS
MOSI
MISO
T
T
T
SEZ
SOH
SDZ
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 29.10. SPI Slave Timing (CKPHA = 0)
NSS
T
T
T
SE
CKL
SD
SCK*
T
CKH
T
T
SIH
SIS
MOSI
T
T
T
SDZ
T
SOH
SLH
SEZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 29.11. SPI Slave Timing (CKPHA = 1)
Rev. 0.2
235
C8051F70x/71x
Table 29.1. SPI Slave Timing Parameters
Parameter
Description
Min
Max
Units
Master Mode Timing (See Figure 29.8 and Figure 29.9)
T
T
T
T
SCK High Time
1 x T
—
—
—
—
ns
ns
ns
ns
MCKH
MCKL
MIS
SYSCLK
SYSCLK
SCK Low Time
1 x T
1 x T
MISO Valid to SCK Shift Edge
SCK Shift Edge to MISO Change
+ 20
SYSCLK
0
MIH
Slave Mode Timing (See Figure 29.10 and Figure 29.11)
T
T
T
T
T
T
T
T
T
T
NSS Falling to First SCK Edge
Last SCK Edge to NSS Rising
NSS Falling to MISO Valid
NSS Rising to MISO High-Z
SCK High Time
2 x T
2 x T
—
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
SE
SYSCLK
SD
SYSCLK
—
4 x T
SYSCLK
SEZ
SDZ
CKH
CKL
SIS
—
4 x T
SYSCLK
5 x T
5 x T
2 x T
2 x T
—
SYSCLK
SYSCLK
SYSCLK
SCK Low Time
—
—
—
MOSI Valid to SCK Sample Edge
SCK Sample Edge to MOSI Change
SCK Shift Edge to MISO Change
SIH
SOH
SLH
SYSCLK
—
4 x T
8 x T
SYSCLK
SYSCLK
Last SCK Edge to MISO Change
(CKPHA = 1 ONLY)
6 x T
SYSCLK
Note: T
is equal to one period of the device system clock (SYSCLK).
SYSCLK
236
Rev. 0.2
C8051F70x/71x
30. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “30.1. Enhanced Baud Rate Generation” on page 238). Received data buffering allows UART0
to start reception of a second incoming data byte before software has finished reading the previous data
byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit register. Reads of SBUF0 always access the buffered Receive register;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF
TB8
SBUF
SET
(TX Shift)
D
Q
TX
CLR
Crossbar
Zero Detector
Stop Bit
Shift
Data
Start
Tx Control
Tx Clock
Send
Tx IRQ
SCON
TI
UART Baud
Rate Generator
Serial
Port
Interrupt
Port I/O
RI
Rx IRQ
Rx Clock
Rx Control
Load
SBUF
Start
Shift
0x1FF
RB8
Input Shift Register
(9 bits)
Load SBUF
SBUF
(RX Latch)
Read
SBUF
SFR Bus
RX
Crossbar
Figure 30.1. UART0 Block Diagram
Rev. 0.2
237
C8051F70x/71x
30.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 30.2), which is not user-
accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1
TL1
UART
Overflow
TX Clock
2
2
TH1
Start
Detected
Overflow
RX Clock
RX Timer
Figure 30.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “31.1.3. Mode 2: 8-bit Coun-
ter/Timer with Auto-Reload” on page 248). The Timer 1 reload value should be set so that overflows will
occur at two times the desired UART baud rate frequency. Timer 1 may be clocked by one of six sources:
SYSCLK, SYSCLK/4, SYSCLK/12, SYSCLK/48, the external oscillator clock/8, or an external input T1. For
any given Timer 1 clock source, the UART0 baud rate is determined by Equation 30.1-A and
Equation 30.1-B.
1
2
A)
B)
--
UartBaudRate = T1_Overflow_Rate
T1CLK
-------------------------
T1_Overflow_Rate =
256 – TH1
Equation 30.1. UART0 Baud Rate
Where T1
is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
CLK
value). Timer 1 clock frequency is selected as described in Section “31. Timers” on page 245. A quick ref-
erence for typical baud rates and system clock frequencies is given in Table 30.1 through Table 30.2. The
internal oscillator may still generate the system clock when the external oscillator is driving Timer 1.
238
Rev. 0.2
C8051F70x/71x
30.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown in Figure 30.3.
TX
RS-232
RS-232
LEVEL
C8051xxxx
RX
XLTR
OR
TX
RX
TX
RX
MCU
C8051xxxx
Figure 30.3. UART Interconnect Diagram
30.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Inter-
rupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data recep-
tion can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data over-
run, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits
are lost.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
SPACE
BIT TIMES
BIT SAMPLING
Figure 30.4. 8-Bit UART Timing Diagram
Rev. 0.2
239
C8051F70x/71x
30.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programma-
ble ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80
(SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in reg-
ister PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB80 (SCON0.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to 1. If the above conditions are not met,
SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to 1. A UART0 interrupt will occur if
enabled when either TI0 or RI0 is set to 1.
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
D8
SPACE
BIT TIMES
BIT SAMPLING
Figure 30.5. 9-Bit UART Timing Diagram
240
Rev. 0.2
C8051F70x/71x
30.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmis-
sions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Master
Device
Slave
Device
Slave
Device
Slave
Device
V+
RX
TX
RX
TX
RX
TX
RX
TX
Figure 30.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 0.2
241
C8051F70x/71x
SFR Definition 30.1. SCON0: Serial Port 0 Control
Bit
7
6
5
4
3
2
1
0
S0MODE
MCE0
REN0
TB80
RB80
TI0
RI0
Name
Type
Reset
R/W
0
R
1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0x98; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
S0MODE Serial Port 0 Operation Mode.
Selects the UART0 Operation Mode.
0: 8-bit UART with Variable Baud Rate.
1: 9-bit UART with Variable Baud Rate.
6
5
Unused Unused. Read = 1b, Write = Don’t Care.
MCE0
Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode:
Mode 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
Mode 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
4
3
2
1
REN0
TB80
RB80
TI0
Receive Enable.
0: UART0 reception disabled.
1: UART0 reception enabled.
Ninth Transmission Bit.
The logic level of this bit will be sent as the ninth transmission bit in 9-bit UART Mode
(Mode 1). Unused in 8-bit mode (Mode 0).
Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the
9th data bit in Mode 1.
Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit
in 8-bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When
the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0
interrupt service routine. This bit must be cleared manually by software.
0
RI0
Receive Interrupt Flag.
Set to 1 by hardware when a byte of data has been received by UART0 (set at the
STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to 1
causes the CPU to vector to the UART0 interrupt service routine. This bit must be
cleared manually by software.
242
Rev. 0.2
C8051F70x/71x
SFR Definition 30.2. SBUF0: Serial (UART0) Port Data Buffer
Bit
7
6
5
4
3
2
1
0
SBUF0[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x99; SFR Page = All Pages
Bit Name
7:0 SBUF0[7:0] Serial Data Buffer Bits 7–0 (MSB–LSB).
Function
This SFR accesses two registers; a transmit shift register and a receive latch register.
When data is written to SBUF0, it goes to the transmit shift register and is held for
serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of
SBUF0 returns the contents of the receive latch.
Rev. 0.2
243
C8051F70x/71x
Table 30.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator
Frequency: 24.5 MHz
1
Target
Baud
Rate%
Error
Oscillator Timer Clock
SCA1–SCA0
(pre-scale
Timer 1
Reload
Value (hex)
T1M
Divide
Factor
Source
Baud Rate
(bps)
1
select)
2
230400
115200
57600
28800
14400
9600
–0.32%
–0.32%
0.15%
–0.32%
0.15%
–0.32%
–0.32%
0.15%
106
212
426
SYSCLK
SYSCLK
SYSCLK
SYSCLK/4
SYSCLK/12
SYSCLK/12
SYSCLK/48
SYSCLK/48
XX
1
1
1
0
0
0
0
0
0xCB
0x96
0x2B
0x96
0xB9
0x96
0x96
0x2B
XX
XX
01
00
00
10
10
848
1704
2544
10176
20448
2400
1200
Notes:
1. SCA1–SCA0 and T1M bit definitions can be found in Section 31.1.
2. X = Don’t care.
Table 30.2. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator
Frequency: 22.1184 MHz
1
Target
Baud
Rate%
Error
Oscillator Timer Clock
SCA1–SCA0
(pre-scale
Timer 1
Reload
Value (hex)
T1M
Divide
Factor
Source
Baud Rate
(bps)
1
select)
2
230400
115200
57600
28800
14400
9600
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
96
192
384
SYSCLK
SYSCLK
SYSCLK
XX
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0xD0
0xA0
0x40
0xE0
0xC0
0xA0
0xA0
0x40
0xFA
0xF4
0xE8
0xD0
0xA0
0x70
XX
XX
00
00
00
10
10
11
11
11
11
11
11
768
SYSCLK / 12
SYSCLK / 12
SYSCLK / 12
SYSCLK / 48
SYSCLK / 48
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
1536
2304
9216
18432
96
192
384
768
1536
2304
2400
1200
230400
115200
57600
28800
14400
9600
Notes:
1. SCA1–SCA0 and T1M bit definitions can be found in Section 31.1.
2. X = Don’t care.
244
Rev. 0.2
C8051F70x/71x
31. Timers
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and two are 16-bit auto-reload timer for use with the ADC, SMBus, or for general purpose
use. These timers 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 and Timer 3 offer 16-bit and split 8-bit timer functionality with auto-reload. Additionally, Timer 3
offers the ability to be clocked from the external oscillator while the device is in Suspend mode, and can be
used as a wake-up source. This allows for implementation of a very low-power system, including RTC
capability.
Timer 0 and Timer 1 Modes:
Timer 2 Modes:
Timer 3 Modes:
13-bit counter/timer
16-bit counter/timer
8-bit counter/timer with
auto-reload
Two 8-bit counter/timers
(Timer 0 only)
16-bit timer with auto-reload
16-bit timer with auto-reload
Two 8-bit timers with auto-reload Two 8-bit timers with auto-reload
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M–
T0M) and the Clock Scale bits (SCA1–SCA0). The Clock Scale bits define a pre-scaled clock from which
Timer 0 and/or Timer 1 may be clocked (See SFR Definition 31.1 for pre-scaled clock selection).
Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
clock source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incremented on each high-to-low transition at the selected input pin (T0 or T1). Events with a fre-
quency of up to one-fourth the system clock frequency can be counted. The input signal need not be peri-
odic, but it should be held at a given level for at least two full system clock cycles to ensure the level is
properly sampled.
Rev. 0.2
245
C8051F70x/71x
SFR Definition 31.1. CKCON: Clock Control
Bit
7
6
5
4
3
2
1
0
T3MH
T3ML
T2MH
T2ML
T1M
T0M
SCA[1:0]
R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
0
0
SFR Address = 0x8E; SFR Page = All Pages
Bit
Name
Function
7
T3MH Timer 3 High Byte Clock Select.
Selects the clock supplied to the Timer 3 high byte (split 8-bit timer mode only).
0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 high byte uses the system clock.
6
T3ML
Timer 3 Low Byte Clock Select.
Selects the clock supplied to Timer 3. Selects the clock supplied to the lower 8-bit timer
in split 8-bit timer mode.
0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 low byte uses the system clock.
5
4
T2MH Timer 2 High Byte Clock Select.
Selects the clock supplied to the Timer 2 high byte (split 8-bit timer mode only).
0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 high byte uses the system clock.
T2ML
Timer 2 Low Byte Clock Select.
Selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer mode,
this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 low byte uses the system clock.
3
2
T1
T0
Timer 1 Clock Select.
Selects the clock source supplied to Timer 1. Ignored when C/T1 is set to 1.
0: Timer 1 uses the clock defined by the prescale bits SCA[1:0].
1: Timer 1 uses the system clock.
Timer 0 Clock Select.
Selects the clock source supplied to Timer 0. Ignored when C/T0 is set to 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits SCA[1:0].
1: Counter/Timer 0 uses the system clock.
1:0 SCA[1:0] Timer 0/1 Prescale Bits.
These bits control the Timer 0/1 Clock Prescaler:
00: System clock divided by 12
01: System clock divided by 4
10: System clock divided by 48
11: External clock divided by 8 (synchronized with the system clock)
246
Rev. 0.2
C8051F70x/71x
31.1. Timer 0 and Timer 1
Each 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 register (TCON) is used to enable Timer 0 and
Timer 1 as well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE regis-
ter (Section “19.2. Interrupt Register Descriptions” on page 125); Timer 1 interrupts can be enabled by set-
ting the ET1 bit in the IE register (Section “19.2. Interrupt Register Descriptions” on page 125). Both
counter/timers operate in one of four primary modes selected by setting the Mode Select bits T1M1–T0M0
in the Counter/Timer Mode register (TMOD). Each timer can be configured independently. Each operating
mode is described below.
31.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers 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 MSBs 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 in TCON is set and an interrupt will occur if Timer 0 interrupts are
enabled.
The C/T0 bit in the TMOD register selects the counter/timer's clock source. When C/T0 is set to logic 1,
high-to-low transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“26.3. Priority Crossbar Decoder” on page 171 for information on selecting and configuring external I/O
pins). Clearing C/T selects the clock defined by the T0M bit in register CKCON. When T0M is set, Timer 0
is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the
Clock Scale bits in CKCON (see SFR Definition 31.1).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 in the TMOD register is logic 0 or the
input signal INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 19.7). Setting
GATE0 to 1 allows the timer to be controlled by the external input signal INT0 (see Section “19.2. Interrupt
Register Descriptions” on page 125), facilitating pulse width measurements
TR0
GATE0
INT0
Counter/Timer
0
1
1
1
X
0
1
1
X
X
0
1
Disabled
Enabled
Disabled
Enabled
Note: X = Don't Care
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
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. The
input signal INT0 is used with Timer 1; the /INT1 polarity is defined by bit IN1PL in register IT01CF (see
SFR Definition 19.7).
Rev. 0.2
247
C8051F70x/71x
TMOD
IT01CF
G C T T G C T T
I I I I I I I I
A
/
1
1 A
/
0
0
N N N N N N N N
T0M
T T M M T T M M
1
1 1 1 0 0 0 0
E 1
1
1
0 E 0
0
1
0
P S S S P S S S
L
L
2
L
1
L
0
L
L
2
L
1
L
0
Pre-scaled Clock
SYSCLK
0
1
0
1
TF1
TR1
TF0
TR0
IE1
IT1
T0
Interrupt
TCLK
TL0
(5 bits)
TH0
(8 bits)
TR0
GATE0
IE0
IT0
Crossbar
IN0PL
XOR
/INT0
Figure 31.1. T0 Mode 0 Block Diagram
31.1.2. 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 coun-
ter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
31.1.3. 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. 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 in the TCON register is set and the counter in TL0 is reloaded
from TH0. If Timer 0 interrupts are 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. Setting the
TR0 bit (TCON.4) enables the timer when either GATE0 in the TMOD register is logic 0 or when the input
signal INT0 is active as defined by bit IN0PL in register IT01CF (see Section “19.3. INT0 and INT1 External
Interrupts” on page 132 for details on the external input signals INT0 and INT1).
248
Rev. 0.2
C8051F70x/71x
TMOD
IT01CF
G C T T G C T T
I I I I I I I I
A
/
1 1 A
/
0 0
N N N N N N N N
1 1 1 1 0 0 0 0
P S S S P S S S
L L L L L L L L
T T M M T T M M
E 1 1 0 E 0 1 0
1
T0M
0
2 1 0
2 1 0
Pre-scaled Clock
SYSCLK
0
1
0
1
T0
TF1
TR1
TF0
TR0
IE1
TCLK
TL0
(8 bits)
Interrupt
TR0
IT1
IE0
IT0
Crossbar
GATE0
TH0
Reload
(8 bits)
IN0PL
XOR
/INT0
Figure 31.2. T0 Mode 2 Block Diagram
31.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The coun-
ter/timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0
and TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register
is restricted to a timer function sourced by the system clock or prescaled 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. When Timer 0 is operating 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 to generate baud rates for the SMBus and/or UART, and/or initiate ADC
conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode set-
tings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1,
configure it for Mode 3.
Rev. 0.2
249
C8051F70x/71x
TMOD
G C T T G C T T
A
/
1
1 A
/ 0 0
T0M
T T M M T T M M
E 1
1
1
0 E 0
0
1 0
Pre-scaled Clock
SYSCLK
0
1
TH0
(8 bits)
TR1
Interrupt
Interrupt
TF1
TR1
TF0
TR0
IE1
0
1
IT1
IE0
IT0
T0
TL0
(8 bits)
TR0
Crossbar
GATE0
IN0PL
XOR
/INT0
Figure 31.3. T0 Mode 3 Block Diagram
250
Rev. 0.2
C8051F70x/71x
SFR Definition 31.2. TCON: Timer Control
Bit
7
6
5
4
3
2
1
0
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0x88; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
TF1
Timer 1 Overflow Flag.
Set to 1 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.
6
5
TR1
TF0
Timer 1 Run Control.
Timer 1 is enabled by setting this bit to 1.
Timer 0 Overflow Flag.
Set to 1 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.
4
3
TR0
IE1
Timer 0 Run Control.
Timer 0 is enabled by setting this bit to 1.
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 in edge-triggered mode.
2
IT1
Interrupt 1 Type Select.
This bit selects whether the configured /INT1 interrupt will be edge or level sensitive.
/INT1 is configured active low or high by the IN1PL bit in the IT01CF register (see
SFR Definition 19.7).
0: /INT1 is level triggered.
1: /INT1 is edge triggered.
1
0
IE0
IT0
External Interrupt 0.
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 0 service routine in edge-triggered mode.
Interrupt 0 Type Select.
This bit selects whether the configured INT0 interrupt will be edge or level sensitive.
INT0 is configured active low or high by the IN0PL bit in register IT01CF (see SFR
Definition 19.7).
0: INT0 is level triggered.
1: INT0 is edge triggered.
Rev. 0.2
251
C8051F70x/71x
SFR Definition 31.3. TMOD: Timer Mode
Bit
7
6
5
4
3
2
1
0
GATE1
C/T1
T1M[1:0]
R/W
GATE0
C/T0
T0M[1:0]
R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
0
0
0
0
SFR Address = 0x89; SFR Page = All Pages
Bit
Name
Function
7
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 is active as defined by bit IN1PL in
register IT01CF (see SFR Definition 19.7).
6
C/T1
Counter/Timer 1 Select.
0: Timer: Timer 1 incremented by clock defined by T1M bit in register CKCON.
1: Counter: Timer 1 incremented by high-to-low transitions on external pin (T1).
5:4
T1M[1:0] Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
00: Mode 0, 13-bit Counter/Timer
01: Mode 1, 16-bit Counter/Timer
10: Mode 2, 8-bit Counter/Timer with Auto-Reload
11: Mode 3, Timer 1 Inactive
3
GATE0
C/T0
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 is active as defined by bit IN0PL in
register IT01CF (see SFR Definition 19.7).
2
Counter/Timer 0 Select.
0: Timer: Timer 0 incremented by clock defined by T0M bit in register CKCON.
1: Counter: Timer 0 incremented by high-to-low transitions on external pin (T0).
1:0
T0M[1:0] Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
00: Mode 0, 13-bit Counter/Timer
01: Mode 1, 16-bit Counter/Timer
10: Mode 2, 8-bit Counter/Timer with Auto-Reload
11: Mode 3, Two 8-bit Counter/Timers
252
Rev. 0.2
C8051F70x/71x
SFR Definition 31.4. TL0: Timer 0 Low Byte
Bit
7
6
5
4
3
2
1
0
TL0[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x8A; SFR Page = All Pages
Bit
Name
Function
7:0
TL0[7:0]
Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
SFR Definition 31.5. TL1: Timer 1 Low Byte
Bit
7
6
5
4
3
2
1
0
TL1[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x8B; SFR Page = All Pages
Bit
Name
Function
7:0
TL1[7:0]
Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
Rev. 0.2
253
C8051F70x/71x
SFR Definition 31.6. TH0: Timer 0 High Byte
Bit
7
6
5
4
3
2
1
0
TH0[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x8C; SFR Page = All Pages
Bit
Name
Function
7:0
TH0[7:0]
Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 31.7. TH1: Timer 1 High Byte
Bit
7
6
5
4
3
2
1
0
TH1[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x8D; SFR Page = All Pages
Bit
Name
Function
7:0
TH1[7:0]
Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
254
Rev. 0.2
C8051F70x/71x
31.2. Timer 2
Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TMR2L (low byte) and TMR2H (high byte). Timer 2 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T2SPLIT bit (TMR2CN.3) defines
the Timer 2 operation mode. Timer 2 can also be used in capture mode to capture rising edges of the
Comparator 0 output.
Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external preci-
sion oscillator. The external oscillator source divided by 8 is synchronized with the system clock.
31.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT (TMR2CN.3) is zero, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2
reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 31.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is
set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled
and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L)
overflow from 0xFF to 0x00.
CKCON
T T T T T T S S
3 3 2 2 1 0 C C
T2XCLK
M M M M M M A A
H L H L
1 0
To ADC,
SMBus
To SMBus
TMR2H
SYSCLK / 12
0
1
TL2
Overflow
0
1
TCLK
TR2
TF2H
TMR2L
Interrupt
External Clock / 8
SYSCLK
TF2L
TF2LEN
TF2CEN
T2SPLIT
TR2
T2XCLK
TMR2RLL TMR2RLH
Reload
Figure 31.4. Timer 2 16-Bit Mode Block Diagram
Rev. 0.2
255
C8051F70x/71x
31.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 31.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH
holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H. TMR2L is
always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
T2MH
T2XCLK TMR2H Clock Source
T2ML
T2XCLK TMR2L Clock Source
0
0
1
0
1
X
SYSCLK / 12
External Clock / 8
SYSCLK
0
0
1
0
1
X
SYSCLK / 12
External Clock / 8
SYSCLK
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time
TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is gener-
ated each time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the
TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags
are not cleared by hardware and must be manually cleared by software.
CKCON
T T T T T T S S
3 3 2 2 1 0 C C
T2XCLK
M M M M M M A A
Reload
TMR2RLH
To SMBus
H L H L
1 0
SYSCLK / 12
0
1
0
External Clock / 8
TCLK
TF2H
TF2L
TMR2H
Interrupt
TR2
1
TF2LEN
TF2CEN
T2SPLIT
TR2
Reload
TMR2RLL
T2XCLK
SYSCLK
1
0
To ADC,
SMBus
TCLK
TMR2L
Figure 31.5. Timer 2 8-Bit Mode Block Diagram
256
Rev. 0.2
C8051F70x/71x
31.2.3. Comparator 0 Capture Mode
The capture mode in Timer 2 allows Comparator 0 rising edges to be captured with the timer clocking from
the system clock or the system clock divided by 12. Timer 2 capture mode is enabled by setting TF2CEN
to 1 and T2SPLIT to 0.
When capture mode is enabled, a capture event will be generated on every Comparator 0 rising edge.
When the capture event occurs, the contents of Timer 2 (TMR2H:TMR2L) are loaded into the Timer 2
reload registers (TMR2RLH:TMR2RLL) and the TF2H flag is set (triggering an interrupt if Timer 2 inter-
rupts are enabled). By recording the difference between two successive timer capture values, the
Comparator 0 period can be determined with respect to the Timer 2 clock. The Timer 2 clock should be
much faster than the capture clock to achieve an accurate reading.
This mode allows software to determine the time between consecutive Comparator 0 rising edges, which
can be used for detecting changes in the capacitance of a capacitive switch, or measuring the frequency of
a low-level analog signal.
CKCON
T2XCLK
T T T T T T S S
3 3 2 2 1 0 C C
MMMMMM A A
H L H L
1 0
SYSCLK / 12
0
1
External Clock / 8
0
1
TCLK
TR2
TMR2L
TMR2H
Capture
SYSCLK
TF2CEN
Comparator 0
Output
TF2H
TF2L
TF2LEN
TF2CEN
T2SPLIT
TR2
Interrupt
TMR2RLL TMR2RLH
T2XCLK
Figure 31.6. Timer 2 Capture Mode Block Diagram
Rev. 0.2
257
C8051F70x/71x
SFR Definition 31.8. TMR2CN: Timer 2 Control
Bit
7
6
5
4
3
2
1
0
TF2H
TF2L
TF2LEN
TF2CEN T2SPLIT
TR2
T2XCLK
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R
0
R/W
0
SFR Address = 0xC8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
TF2H
Timer 2 High Byte Overflow Flag.
Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit
mode, this will occur 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.
6
TF2L
Timer 2 Low Byte Overflow Flag.
Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. TF2L will
be set when the low byte overflows regardless of the Timer 2 mode. This bit is not
automatically cleared by hardware.
5
4
TF2LEN
TF2CEN
Timer 2 Low Byte Interrupt Enable.
When set to 1, this bit enables Timer 2 Low Byte interrupts. If Timer 2 interrupts are
also enabled, an interrupt will be generated when the low byte of Timer 2 overflows.
Timer 2 Comparator Capture Enable.
When set to 1, this bit enables Timer 2 Comparator Capture Mode. If TF2CEN is set,
on a rising edge of the Comparator0 output the current 16-bit timer value in
TMR2H:TMR2L will be copied to TMR2RLH:TMR2RLL. If Timer 2 interrupts are also
enabled, an interrupt will be generated on this event.
3
2
T2SPLIT
TR2
Timer 2 Split Mode Enable.
When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload.
0: Timer 2 operates in 16-bit auto-reload mode.
1: Timer 2 operates as two 8-bit auto-reload timers.
Timer 2 Run Control.
Timer 2 is enabled by setting this bit to 1. In 8-bit mode, this bit enables/disables
TMR2H only; TMR2L is always enabled in split mode.
1
0
Unused
T2XCLK
Unused. Read = 0b; Write = Don’t Care.
Timer 2 External Clock Select.
This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this
bit selects the external oscillator clock source for both timer bytes. However, the
Timer 2 Clock Select bits (T2MH and T2ML in register CKCON) may still be used to
select between the external clock and the system clock for either timer.
0: Timer 2 clock is the system clock divided by 12.
1: Timer 2 clock is the external clock divided by 8 (synchronized with SYSCLK).
258
Rev. 0.2
C8051F70x/71x
SFR Definition 31.9. TMR2RLL: Timer 2 Reload Register Low Byte
Bit
7
6
5
4
3
2
1
0
TMR2RLL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xCA; SFR Page = 0
Bit Name
Function
7:0 TMR2RLL[7:0] Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2.
SFR Definition 31.10. TMR2RLH: Timer 2 Reload Register High Byte
Bit
7
6
5
4
3
2
1
0
TMR2RLH[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xCB; SFR Page = 0
Bit Name
Function
7:0 TMR2RLH[7:0] Timer 2 Reload Register High Byte.
TMR2RLH holds the high byte of the reload value for Timer 2.
Rev. 0.2
259
C8051F70x/71x
SFR Definition 31.11. TMR2L: Timer 2 Low Byte
Bit
7
6
5
4
3
2
1
0
TMR2L[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xCC; SFR Page = 0
Bit Name
7:0 TMR2L[7:0] Timer 2 Low Byte.
Function
In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8-
bit mode, TMR2L contains the 8-bit low byte timer value.
SFR Definition 31.12. TMR2H Timer 2 High Byte
Bit
7
6
5
4
3
2
1
0
TMR2H[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xCD; SFR Page = 0
Bit Name
7:0 TMR2H[7:0] Timer 2 Low Byte.
Function
In 16-bit mode, the TMR2H register contains the high byte of the 16-bit Timer 2. In 8-
bit mode, TMR2H contains the 8-bit high byte timer value.
260
Rev. 0.2
C8051F70x/71x
31.3. Timer 3
Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3SPLIT bit (TMR3CN.3) defines
the Timer 3 operation mode.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal high-frequency oscillator drives the system clock while Timer 3 is clocked by an external oscillator
source. The external oscillator source divided by 8 is synchronized with the system clock when in all oper-
ating modes except suspend. When the internal oscillator is placed in suspend mode, The external clock/8
signal can directly drive the timer. This allows the use of an external clock to wake up the device from sus-
pend mode. The timer will continue to run in suspend mode and count up. When the timer overflow occurs,
the device will wake from suspend mode, and begin executing code again. The timer value may be set
prior to entering suspend, to overflow in the desired amount of time (number of clocks) to wake the device.
If a wake-up source other than the timer wakes the device from suspend mode, it may take up to three
timer clocks before the timer registers can be read or written. During this time, the STSYNC bit in register
OSCICN will be set to 1, to indicate that it is not safe to read or write the timer registers.
31.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3
reload registers (TMR3RLH and TMR3RLL) is loaded into the Timer 3 register as shown in Figure 31.7,
and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled (if EIE1.7 is
set), an interrupt will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled
and the TF3LEN bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L)
overflow from 0xFF to 0x00.
CKCON
T T T T T T S S
3 3 2 2 1 0 C C
M M M M M M A A
T3XCLK
0
H L H L
1 0
To ADC
SYSCLK / 12
0
1
TCLK
TR3
TF3H
TF3L
TF3LEN
TF3CEN
T3SPLIT
TR3
TMR3L
TMR3H
Interrupt
External Clock / 8
1
SYSCLK
T3XCLK
TMR3RLL TMR3RLH
Reload
Figure 31.7. Timer 3 16-Bit Mode Block Diagram
Rev. 0.2
261
C8051F70x/71x
31.3.2. 8-bit Timers with Auto-Reload
When T3SPLIT is set, Timer 3 operates as two 8-bit timers (TMR3H and TMR3L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 31.8. TMR3RLL holds the reload value for TMR3L; TMR3RLH
holds the reload value for TMR3H. The TR3 bit in TMR3CN handles the run control for TMR3H. TMR3L is
always running when configured for 8-bit Mode. Timer 3 can also be used in capture mode to capture rising
edges of the Comparator 0 output.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 3 clock select bits (T3MH and T3ML in CKCON) select either SYSCLK or
the clock defined by the Timer 3 External Clock Select bits (T3XCLK in TMR3CN), as follows:
T3MH
T3XCLK
TMR3H Clock
Source
T3ML
T3XCLK
TMR3L Clock
Source
0
0
1
0
1
X
SYSCLK / 12
External Clock / 8
SYSCLK
0
0
1
0
1
X
SYSCLK / 12
External Clock / 8
SYSCLK
The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows
from 0xFF to 0x00. When Timer 3 interrupts are enabled, an interrupt is generated each time TMR3H over-
flows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each
time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the TF3H and
TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not
cleared by hardware and must be manually cleared by software.
CKCON
T T T T T T S S
3 3 2 2 1 0 C C
T3XCLK
M M M M M M A A
Reload
TMR3RLH
H L H L
1 0
SYSCLK / 12
0
1
0
1
External Clock / 8
TCLK
TF3H
TF3L
TF3LEN
TF3CEN
T3SPLIT
TR3
TMR3H
Interrupt
TR3
Reload
TMR3RLL
T3XCLK
SYSCLK
1
0
TCLK
TMR3L
To ADC
Figure 31.8. Timer 3 8-Bit Mode Block Diagram
262
Rev. 0.2
C8051F70x/71x
31.3.3. Comparator 0 Capture Mode
The capture mode in Timer 3 allows Comparator 0 rising edges to be captured with the timer clocking from
the system clock or the system clock divided by 12. Timer 3 capture mode is enabled by setting TF3CEN
to 1 and T3SPLIT to 0.
When capture mode is enabled, a capture event will be generated on every Comparator 0 rising edge.
When the capture event occurs, the contents of Timer 3 (TMR3H:TMR3L) are loaded into the Timer 3
reload registers (TMR3RLH:TMR3RLL) and the TF3H flag is set (triggering an interrupt if Timer 3 inter-
rupts are enabled). By recording the difference between two successive timer capture values, the
Comparator 0 period can be determined with respect to the Timer 3 clock. The Timer 3 clock should be
much faster than the capture clock to achieve an accurate reading.
This mode allows software to determine the time between consecutive Comparator 0 rising edges, which
can be used for detecting changes in the capacitance of a capacitive switch, or measuring the frequency of
a low-level analog signal.
CKCON
T3XCLK
T T T T T T S S
3 3 2 2 1 0 C C
MMMMM M A A
H L H L
1 0
SYSCLK / 12
0
1
External Clock / 8
0
1
TCLK
TR3
TMR3L
TMR3H
Capture
SYSCLK
TF3CEN
Comparator 0
Output
TF3H
TF3L
TF3LEN
TF3CEN
T3SPLIT
TR3
Interrupt
TMR3RLL TMR3RLH
T3XCLK
Figure 31.9. Timer 3 Capture Mode Block Diagram
Rev. 0.2
263
C8051F70x/71x
SFR Definition 31.13. TMR3CN: Timer 3 Control
Bit
7
6
5
4
3
2
1
0
TF3H
TF3L
TF3LEN
TF3CEN T3SPLIT
TR3
T3XCLK
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R
0
R/W
0
SFR Address = 0x91; SFR Page = 0
Bit
Name
Function
7
TF3H
Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit
mode, this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the
Timer 3 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 3
interrupt service routine. This bit is not automatically cleared by hardware.
6
TF3L
Timer 3 Low Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. TF3L will
be set when the low byte overflows regardless of the Timer 3 mode. This bit is not
automatically cleared by hardware.
5
4
TF3LEN
TF3CEN
Timer 3 Low Byte Interrupt Enable.
When set to 1, this bit enables Timer 3 Low Byte interrupts. If Timer 3 interrupts are
also enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
Timer 3 Comparator Capture Enable.
When set to 1, this bit enables Timer 3 Comparator Capture Mode. If TF3CEN is set,
on a rising edge of the Comparator0 output the current 16-bit timer value in
TMR3H:TMR3L will be copied to TMR3RLH:TMR3RLL. If Timer 3 interrupts are also
enabled, an interrupt will be generated on this event.
3
2
T3SPLIT
TR3
Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 operates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timers.
Timer 3 Run Control.
Timer 3 is enabled by setting this bit to 1. In 8-bit mode, this bit enables/disables
TMR3H only; TMR3L is always enabled in split mode.
1
0
Unused
T3XCLK
Unused. Read = 0b; Write = Don’t Care.
Timer 3 External Clock Select.
This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this
bit selects the external oscillator clock source for both timer bytes. However, the
Timer 3 Clock Select bits (T3MH and T3ML in register CKCON) may still be used to
select between the external clock and the system clock for either timer.
0: System clock divided by 12.
1: External clock divided by 8 (synchronized with SYSCLK when not in suspend).
264
Rev. 0.2
C8051F70x/71x
SFR Definition 31.14. TMR3RLL: Timer 3 Reload Register Low Byte
Bit
7
6
5
4
3
2
1
0
TMR3RLL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x92; SFR Page = 0
Bit Name
Function
7:0 TMR3RLL[7:0] Timer 3 Reload Register Low Byte.
TMR3RLL holds the low byte of the reload value for Timer 3.
SFR Definition 31.15. TMR3RLH: Timer 3 Reload Register High Byte
Bit
7
6
5
4
3
2
1
0
TMR3RLH[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x93; SFR Page = 0
Bit Name
Function
7:0 TMR3RLH[7:0] Timer 3 Reload Register High Byte.
TMR3RLH holds the high byte of the reload value for Timer 3.
Rev. 0.2
265
C8051F70x/71x
SFR Definition 31.16. TMR3L: Timer 3 Low Byte
Bit
7
6
5
4
3
2
1
0
TMR3L[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x94; SFR Page = 0
Bit
Name
Function
7:0
TMR3L[7:0] Timer 3 Low Byte.
In 16-bit mode, the TMR3L register contains the low byte of the 16-bit Timer 3. In
8-bit mode, TMR3L contains the 8-bit low byte timer value.
SFR Definition 31.17. TMR3H Timer 3 High Byte
Bit
7
6
5
4
3
2
1
0
TMR3H[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
SFR Address = 0x95; SFR Page = 0
Bit
Name
Function
7:0
TMR3H[7:0] Timer 3 High Byte.
In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In
8-bit mode, TMR3H contains the 8-bit high byte timer value.
266
Rev. 0.2
C8051F70x/71x
32. Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and three 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled. The counter/timer is driven by a
programmable timebase that can select between seven sources: system clock, system clock divided by
four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflows, or
an external clock signal on the ECI input pin. Each capture/compare module may be configured to operate
independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Fre-
quency Output,
8 to 11-Bit PWM, or 16-Bit PWM (each mode is described in Section
“32.3. Capture/Compare Modules” on page 269). The external oscillator clock option is ideal for real-time
clock (RTC) functionality, allowing the PCA to be clocked by a precision external oscillator while the inter-
nal oscillator drives the system clock. The PCA is configured and controlled through the system controller's
Special Function Registers. The PCA block diagram is shown in Figure 32.1
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
PCA
16-Bit Counter/Timer
CLOCK
MUX
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Crossbar
Port I/O
Figure 32.1. PCA Block Diagram
Rev. 0.2
267
C8051F70x/71x
32.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register.
Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter.
Reading PCA0H or PCA0L does not disturb the counter operation. The CPS2–CPS0 bits in the PCA0MD
register select the timebase for the counter/timer as shown in Table 32.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft-
ware. Clearing the CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the
CPU is in Idle mode.
Table 32.1. PCA Timebase Input Options
CPS2
CPS1
CPS0 Timebase
0
0
0
0
0
0
1
1
0
1
0
1
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock divided
by 4)
1
1
1
0
0
1
0
1
x
System clock
External oscillator source divided by 8
Reserved
*
Note: External oscillator source divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
C C C E
PCA0CN
C
I
D
L
C C
F R
C C C
C C C
F F F
2 1 0
P P P C
S S S F
2 1 0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
000
001
010
011
100
101
Timer 0 Overflow
ECI
0
Overflow
To PCA Interrupt System
PCA0H
PCA0L
1
SYSCLK
CF
External Clock/8
To PCA Modules
Figure 32.2. PCA Counter/Timer Block Diagram
268
Rev. 0.2
C8051F70x/71x
32.2. PCA0 Interrupt Sources
Figure 32.3 shows a diagram of the PCA interrupt tree. There are eight independent event flags that can
be used to generate a PCA0 interrupt. They are: the main PCA counter overflow flag (CF), which is set
upon a 16-bit overflow of the PCA0 counter, an intermediate overflow flag (COVF), which can be set on an
overflow from the 8th, 9th, 10th, or 11th bit of the PCA0 counter, and the individual flags for each PCA
channel (CCF0, CCF1, and CCF2), which are set according to the operation mode of that module. These
event flags are always set when the trigger condition occurs. Each of these flags can be individually
selected to generate a PCA0 interrupt, using the corresponding interrupt enable flag (ECF for CF, ECOV
for COVF, and ECCFn for each CCFn). PCA0 interrupts must be globally enabled before any individual
interrupt sources are recognized by the processor. PCA0 interrupts are globally enabled by setting the EA
bit and the EPCA0 bit to logic 1.
(for n = 0 to 2)
PCA0CPMn
PCA0CN
PCA0MD
C C C E
PCA0PWM
P E C C M T P E
WC A A A O W C
MO P P T G M C
1 M P N n n n F
6 n n n
n
C C
F R
C C C
C C C
F F F
2 1 0
C
I
D
L
A C E
C C
L L
S S
E E
L L
1 0
P P P C
S S S F
2 1 0
R O C
S V O
E F V
L
n
PCA Counter/Timer 8, 9,
10 or 11-bit Overflow
Set 8, 9, 10, or 11 bit Operation
EPCA0
0
1
PCA Counter/Timer 16-
bit Overflow
0
1
EA
ECCF0
ECCF1
ECCF2
Interrupt
Priority
Decoder
0
1
0
1
0
1
PCA Module 0
(CCF0)
0
1
PCA Module 1
(CCF1)
0
1
PCA Module 2
(CCF2)
Figure 32.3. PCA Interrupt Block Diagram
32.3. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8 to 11-Bit Pulse Width Modulator, or 16-
Bit Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the
CIP-51 system controller. These registers are used to exchange data with a module and configure the
module's mode of operation. Table 32.2 summarizes the bit settings in the PCA0CPMn and PCA0PWM
registers used to select the PCA capture/compare module’s operating mode. All modules set to use 8, 9,
10, or 11-bit PWM mode must use the same cycle length (8-11 bits). Setting the ECCFn bit in a
PCA0CPMn register enables the module's CCFn interrupt.
Rev. 0.2
269
C8051F70x/71x
Table 32.2. PCA0CPM and PCA0PWM Bit Settings for PCA Capture/Compare
Modules
Operational Mode
PCA0CPMn
PCA0PWM
Bit Number
7 6 5 4 3 2 1 0 7 6 5 4-2
1–0
Capture triggered by positive edge on CEXn
Capture triggered by negative edge on CEXn
Capture triggered by any transition on CEXn
Software Timer
X X 1 0 0 0 0 A 0 X B XXX XX
X X 0 1 0 0 0 A 0 X B XXX XX
X X 1 1 0 0 0 A 0 X B XXX XX
X C 0 0 1 0 0 A 0 X B XXX XX
X C 0 0 1 1 0 A 0 X B XXX XX
X C 0 0 0 1 1 A 0 X B XXX XX
0 C 0 0 E 0 1 A 0 X B XXX 00
0 C 0 0 E 0 1 A D X B XXX 01
0 C 0 0 E 0 1 A D X B XXX 10
0 C 0 0 E 0 1 A D X B XXX 11
1 C 0 0 E 0 1 A 0 X B XXX XX
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator (Note 7)
9-Bit Pulse Width Modulator (Note 7)
10-Bit Pulse Width Modulator (Note 7)
11-Bit Pulse Width Modulator (Note 7)
16-Bit Pulse Width Modulator
Notes:
1. X = Don’t Care (no functional difference for individual module if 1 or 0).
2. A = Enable interrupts for this module (PCA interrupt triggered on CCFn set to 1).
3. B = Enable 8th, 9th, 10th or 11th bit overflow interrupt (Depends on setting of CLSEL[1:0]).
4. C = When set to 0, the digital comparator is off. For high speed and frequency output modes, the
associated pin will not toggle. In any of the PWM modes, this generates a 0% duty cycle (output = 0).
5. D = Selects whether the Capture/Compare register (0) or the Auto-Reload register (1) for the associated
channel is accessed via addresses PCA0CPHn and PCA0CPLn.
6. E = When set, a match event will cause the CCFn flag for the associated channel to be set.
7. All modules set to 8, 9, 10 or 11-bit PWM mode use the same cycle length setting.
270
Rev. 0.2
C8051F70x/71x
32.3.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA coun-
ter/timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transi-
tion that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1. An interrupt request is generated if the CCFn interrupt for that module is
enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt ser-
vice routine, and must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the
state of the Port pin associated with CEXn can be read directly to determine whether a rising-edge or fall-
ing-edge caused the capture.
PCA Interrupt
PCA0CPMn
P E C C M T P E
WC A A A O W C
M O P P T G M C
1 M P N n n n F
6 n n n
n
PCA0CN
C C
F R
C C C
C C C
F F F
2 1 0
n
x
x
0 0 0
x
PCA0CPLn
PCA0CPHn
0
1
CEXn
Capture
Port I/O
Crossbar
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 32.4. PCA Capture Mode Diagram
Note: The CEXn input signal must remain high or low for at least 2 system clock cycles to be recognized by the
hardware.
Rev. 0.2
271
C8051F70x/71x
32.3.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1. An interrupt request is generated if the CCFn interrupt for that module is
enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt ser-
vice routine, and must be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn regis-
ter enables Software Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1.
Write to
0
PCA0CPLn
ENB
Reset
Write to
PCA0CPHn
ENB
PCA Interrupt
1
PCA0CPMn
P E C C M T P E
WC A A A O W C
M O P P T G M C
1 M P N n n n F
PCA0CN
C C C C C
F R
C C C
F F F
2 1 0
PCA0CPLn
PCA0CPHn
6 n n n
n
n
x
0
0
0 0
x
0
1
Enable
Match
16-bit Comparator
PCA
Timebase
PCA0L
PCA0H
Figure 32.5. PCA Software Timer Mode Diagram
272
Rev. 0.2
C8051F70x/71x
32.3.3. High-Speed Output Mode
In High-Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1. An
interrupt request is generated if the CCFn interrupt for that module is enabled. The CCFn bit is not auto-
matically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared
by software. Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-
Speed Output mode. If ECOMn is cleared, the associated pin will retain its state, and not toggle on the next
match event.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1.
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPMn
Write to
PCA0CPHn
P E C C M T P E
WC A A A O W C
MO P P T G M C
1 M P N n n n F
ENB
1
6 n n n
n
n
x
0 0
0
x
PCA Interrupt
PCA0CN
C C C C C
F R
C C C
F F F
2 1 0
PCA0CPLn
PCA0CPHn
0
1
Enable
Match
16-bit Comparator
TOGn
Toggle
0
CEXn
Crossbar
Port I/O
1
PCA
Timebase
PCA0L
PCA0H
Figure 32.6. PCA High-Speed Output Mode Diagram
Rev. 0.2
273
C8051F70x/71x
32.3.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the out-
put is toggled. The frequency of the square wave is then defined by Equation 32.1.
FPCA
----------------------------------------
=
FCEXn
2 PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Equation 32.1. Square Wave Frequency Output
Where F
is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
PCA
PCA0MD. The lower byte of the capture/compare module is compared to the PCA counter low byte; on a
match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn.
Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn reg-
ister. The MATn bit should normally be set to 0 in this mode. If the MATn bit is set to 1, the CCFn flag for
the channel will be set when the 16-bit PCA0 counter and the 16-bit capture/compare register for the chan-
nel are equal.
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPMn
P E C C M T P E
WC A A A O W C
MO P P T G M C
1 M P N n n n F
Write to
PCA0CPHn
ENB
PCA0CPLn
8-bit Adder
PCA0CPHn
1
Adder
Enable
6 n n n
n
n
TOGn
x
0 0 0
x
Toggle
0
CEXn
8-bit
Comparator
match
Enable
Crossbar
Port I/O
1
PCA Timebase
PCA0L
Figure 32.7. PCA Frequency Output Mode
274
Rev. 0.2
C8051F70x/71x
32.3.5. 8-bit, 9-bit, 10-bit and 11-bit Pulse Width Modulator Modes
Each module can be used independently to generate a pulse width modulated (PWM) output on its associ-
ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer, and
the setting of the PWM cycle length (8, 9, 10 or 11-bits). For backwards-compatibility with the 8-bit PWM
mode available on other devices, the 8-bit PWM mode operates slightly different than 9, 10 and 11-bit
PWM modes. It is important to note that all channels configured for 8/9/10/11-bit PWM mode will use
the same cycle length. It is not possible to configure one channel for 8-bit PWM mode and another for 11-
bit mode (for example). However, other PCA channels can be configured to Pin Capture, High-Speed Out-
put, Software Timer, Frequency Output, or 16-bit PWM mode independently.
32.3.5.1. 8-bit Pulse Width Modulator Mode
The duty cycle of the PWM output signal in 8-bit PWM mode is varied using the module's PCA0CPLn cap-
ture/compare register. When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the
value in PCA0CPLn, the output on the CEXn pin will be set. When the count value in PCA0L overflows, the
CEXn output will be reset (see Figure 32.8). Also, when the counter/timer low byte (PCA0L) overflows from
0xFF to 0x00, PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare
high byte (PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the
PCA0CPMn register, and setting the CLSEL bits in register PCA0PWM to 00b enables 8-Bit Pulse Width
Modulator mode. If the MATn bit is set to 1, the CCFn flag for the module will be set each time an 8-bit
comparator match (rising edge) occurs. The COVF flag in PCA0PWM can be used to detect the overflow
(falling edge), which will occur every 256 PCA clock cycles. The duty cycle for 8-Bit PWM Mode is given in
Equation 32.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1.
256 – PCA0CPHn
---------------------------------------------------
Duty Cycle =
256
Equation 32.2. 8-Bit PWM Duty Cycle
Using Equation 32.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0.
Rev. 0.2
275
C8051F70x/71x
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPHn
PCA0CPLn
Write to
PCA0CPHn
ENB
COVF
1
PCA0PWM
A E C
R C O
S O V
E V F
L
PCA0CPMn
C C
L L
S S
E E
L L
1 0
P E C C M T P E
WC A A A O W C
M O P P T G M C
1 M P N n n n F
6 n n n
n
n
0
x
0
0
0
0 0 x 0
x
8-bit
Comparator
match
SET
CLR
CEXn
Enable
S
R
Q
Q
Crossbar
Port I/O
PCA Timebase
PCA0L
Overflow
Figure 32.8. PCA 8-Bit PWM Mode Diagram
32.3.5.2. 9/10/11-bit Pulse Width Modulator Mode
The duty cycle of the PWM output signal in 9/10/11-bit PWM mode should be varied by writing to an “Auto-
Reload” Register, which is dual-mapped into the PCA0CPHn and PCA0CPLn register locations. The data
written to define the duty cycle should be right-justified in the registers. The auto-reload registers are
accessed (read or written) when the bit ARSEL in PCA0PWM is set to 1. The capture/compare registers
are accessed when ARSEL is set to 0.
When the least-significant N bits of the PCA0 counter match the value in the associated module’s cap-
ture/compare register (PCA0CPn), the output on CEXn is asserted high. When the counter overflows from
the Nth bit, CEXn is asserted low (see Figure 32.9). Upon an overflow from the Nth bit, the COVF flag is
set, and the value stored in the module’s auto-reload register is loaded into the capture/compare register.
The value of N is determined by the CLSEL bits in register PCA0PWM.
The 9, 10 or 11-bit PWM mode is selected by setting the ECOMn and PWMn bits in the PCA0CPMn regis-
ter, and setting the CLSEL bits in register PCA0PWM to the desired cycle length (other than 8-bits). If the
MATn bit is set to 1, the CCFn flag for the module will be set each time a comparator match (rising edge)
occurs. The COVF flag in PCA0PWM can be used to detect the overflow (falling edge), which will occur
every 512 (9-bit), 1024 (10-bit) or 2048 (11-bit) PCA clock cycles. The duty cycle for 9/10/11-Bit PWM
Mode is given in Equation 32.2, where N is the number of bits in the PWM cycle.
Important Note About PCA0CPHn and PCA0CPLn Registers: When writing a 16-bit value to the
PCA0CPn registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn
bit to 0; writing to PCA0CPHn sets ECOMn to 1.
2N – PCA0CPn
-------------------------------------------
Duty Cycle =
2N
Equation 32.3. 9, 10, and 11-Bit PWM Duty Cycle
A 0% duty cycle may be generated by clearing the ECOMn bit to 0.
276
Rev. 0.2
C8051F70x/71x
Write to
0
PCA0CPLn
R/W when
ARSEL = 1
ENB
(Auto-Reload)
PCA0CPH:Ln
(right-justified)
PCA0PWM
Reset
A E C
R C O
S O V
E V F
L
C C
L L
S S
E E
L L
1 0
Write to
PCA0CPHn
ENB
1
PCA0CPMn
x
P E C C M T P E
WC A A A O W C
MO P P T G M C
1 M P N n n n F
R/W when
ARSEL = 0
(Capture/Compare)
Set “N” bits:
01 = 9 bits
10 = 10 bits
11 = 11 bits
PCA0CPH:Ln
(right-justified)
6 n n n
n
n
0
0 0 x 0
x
match
SET
CEXn
Enable
N-bit Comparator
S
R
Q
Q
Crossbar
Port I/O
CLR
PCA Timebase
PCA0H:L
Overflow of Nth Bit
Figure 32.9. PCA 9, 10 and 11-Bit PWM Mode Diagram
Rev. 0.2
277
C8051F70x/71x
32.3.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. 16-bit PWM mode is independent of the other
(8/9/10/11-bit) PWM modes. In this mode, the 16-bit capture/compare module defines the number of PCA
clocks for the low time of the PWM signal. When the PCA counter matches the module contents, the out-
put on CEXn is asserted high; when the 16-bit counter overflows, CEXn is asserted low. To output a vary-
ing duty cycle, new value writes should be synchronized with PCA CCFn match interrupts. 16-Bit PWM
Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn register. For a vary-
ing duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help synchronize the
capture/compare register writes. If the MATn bit is set to 1, the CCFn flag for the module will be set each
time a 16-bit comparator match (rising edge) occurs. The CF flag in PCA0CN can be used to detect the
overflow (falling edge). The duty cycle for 16-Bit PWM Mode is given by Equation 32.4.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1.
65536 – PCA0CPn
----------------------------------------------------
Duty Cycle =
65536
Equation 32.4. 16-Bit PWM Duty Cycle
Using Equation 32.4, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0.
Write to
0
PCA0CPLn
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P E C C M T P E
WC A A A O W C
M O P P T G M C
PCA0CPHn
PCA0CPLn
1 M P N n
n
n
F
n
6
n
1
n
n
n
0
0
x
0
x
match
SET
CLR
CEXn
Enable
16-bit Comparator
S
R
Q
Q
Crossbar
Port I/O
PCA Timebase
PCA0H
PCA0L
Overflow
Figure 32.10. PCA 16-Bit PWM Mode
278
Rev. 0.2
C8051F70x/71x
32.4. Register Descriptions for PCA0
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 32.1. PCA0CN: PCA Control
Bit
7
6
5
4
3
2
1
0
CF
CR
CCF2
CCF1
CCF0
Name
Type
Reset
R/W
0
R/W
0
R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xD8; SFR Page = All Pages; Bit-Addressable
Bit
Name
Function
7
CF
PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA Counter/Timer overflows from 0xFFFF to 0x0000.
When the Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the
CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared
by hardware and must be cleared by software.
6
CR
PCA Counter/Timer Run Control.
This bit enables/disables the PCA Counter/Timer.
0: PCA Counter/Timer disabled.
1: PCA Counter/Timer enabled.
5:3
Unused Unused. Read = 000b; Write = Don’t care
2:0 CCF[2:0] PCA Module n Capture/Compare Flag.
These bits are set by hardware when a match or capture occurs in the associated PCA
Module n. When the CCFn interrupt is enabled, setting this bit causes the CPU to
vector to the PCA interrupt service routine. This bit is not automatically cleared by
hardware and must be cleared by software.
Rev. 0.2
279
C8051F70x/71x
SFR Definition 32.2. PCA0MD: PCA Mode
Bit
7
6
5
4
3
2
1
0
CIDL
CPS2
CPS1
CPS0
ECF
Name
Type
Reset
R/W
0
R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xED; SFR Page = F
Bit
Name
Function
7
CIDL
PCA Counter/Timer Idle Control.
Specifies PCA behavior when CPU is in Idle Mode.
0: PCA continues to function normally while the system controller is in Idle Mode.
1: PCA operation is suspended while the system controller is in Idle Mode.
6:5
4
Unused Unused. Read = 00b; Write = Don’t Care
Unused Read = 0b, Write = don't care.
3:1 CPS[2:0] PCA Counter/Timer Pulse Select.
These bits select the timebase source for the PCA counter
000: System clock divided by 12
001: System clock divided by 4
010: Timer 0 overflow
011: High-to-low transitions on ECI (max rate = system clock divided by 4)
100: System clock
101: External clock divided by 8 (synchronized with the system clock)
110-111: Reserved
0
ECF
PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA Counter/Timer Overflow (CF) interrupt.
0: Disable the CF interrupt.
1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is
set.
280
Rev. 0.2
C8051F70x/71x
SFR Definition 32.3. PCA0PWM: PCA PWM Configuration
Bit
7
6
5
4
3
2
1
0
ARSEL
ECOV
COVF
CLSEL[1:0]
R/W
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R
0
R
0
R
0
0
0
SFR Address = 0xA1; SFR Page = F
Bit
Name
Function
7
ARSEL
Auto-Reload Register Select.
This bit selects whether to read and write the normal PCA capture/compare registers
(PCA0CPn), or the Auto-Reload registers at the same SFR addresses. This function
is used to define the reload value for 9, 10, and 11-bit PWM modes. In all other
modes, the Auto-Reload registers have no function.
0: Read/Write Capture/Compare Registers at PCA0CPHn and PCA0CPLn.
1: Read/Write Auto-Reload Registers at PCA0CPHn and PCA0CPLn.
6
5
ECOV
COVF
Cycle Overflow Interrupt Enable.
This bit sets the masking of the Cycle Overflow Flag (COVF) interrupt.
0: COVF will not generate PCA interrupts.
1: A PCA interrupt will be generated when COVF is set.
Cycle Overflow Flag.
This bit indicates an overflow of the 8th, 9th, 10th, or 11th bit of the main PCA counter
(PCA0). The specific bit used for this flag depends on the setting of the Cycle Length
Select bits. The bit can be set by hardware or software, but must be cleared by soft-
ware.
0: No overflow has occurred since the last time this bit was cleared.
1: An overflow has occurred since the last time this bit was cleared.
4:2
Unused
Read = 000b; Write = don’t care.
1:0 CLSEL[1:0] Cycle Length Select.
When 16-bit PWM mode is not selected, these bits select the length of the PWM
cycle, between 8, 9, 10, or 11 bits. This affects all channels configured for PWM which
are not using 16-bit PWM mode. These bits are ignored for individual channels config-
ured to16-bit PWM mode.
00: 8 bits.
01: 9 bits.
10: 10 bits.
11: 11 bits.
Rev. 0.2
281
C8051F70x/71x
SFR Definition 32.4. PCA0CPMn: PCA Capture/Compare Mode
Bit
7
6
5
4
3
2
1
0
PWM16n
ECOMn
CAPPn
CAPNn
MATn
TOGn
PWMn
ECCFn
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Addresses: PCA0CPM0 = 0xDA, PCA0CPM1 = 0xDB, PCA0CPM2 = 0xDC
SFR Pages:
PCA0CPM0 = F, PCA0CPM1 = F, PCA0CPM2 = F
Bit
Name
Function
7
PWM16n 16-bit Pulse Width Modulation Enable.
This bit enables 16-bit mode when Pulse Width Modulation mode is enabled.
0: 8 to 11-bit PWM selected.
1: 16-bit PWM selected.
6
5
4
3
ECOMn Comparator Function Enable.
This bit enables the comparator function for PCA module n when set to 1.
CAPPn Capture Positive Function Enable.
This bit enables the positive edge capture for PCA module n when set to 1.
CAPNn Capture Negative Function Enable.
This bit enables the negative edge capture for PCA module n when set to 1.
MATn
Match Function Enable.
This bit enables the match function for PCA module n when set to 1. When enabled,
matches of the PCA counter with a module's capture/compare register cause the CCFn
bit in PCA0MD register to be set to logic 1.
2
1
0
TOGn
Toggle Function Enable.
This bit enables the toggle function for PCA module n when set to 1. When enabled,
matches of the PCA counter with a module's capture/compare register cause the logic
level on the CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module oper-
ates in Frequency Output Mode.
PWMn Pulse Width Modulation Mode Enable.
This bit enables the PWM function for PCA module n when set to 1. When enabled, a
pulse width modulated signal is output on the CEXn pin. 8 to 11-bit PWM is used if
PWM16n is cleared; 16-bit mode is used if PWM16n is set to logic 1. If the TOGn bit is
also set, the module operates in Frequency Output Mode.
ECCFn Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
282
Rev. 0.2
C8051F70x/71x
SFR Definition 32.5. PCA0L: PCA Counter/Timer Low Byte
Bit
7
6
5
4
3
2
1
0
PCA0[7:0]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xF9; SFR Page = 0
Bit Name
7:0 PCA0[7:0] PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
Function
SFR Definition 32.6. PCA0H: PCA Counter/Timer High Byte
Bit
7
6
5
4
3
2
1
0
PCA0[15:8]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xFA; SFR Page = 0
Bit Name
7:0 PCA0[15:8] PCA Counter/Timer High Byte.
Function
The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
Reads of this register will read the contents of a “snapshot” register, whose contents
are updated only when the contents of PCA0L are read (see Section 32.1).
Rev. 0.2
283
C8051F70x/71x
SFR Definition 32.7. PCA0CPLn: PCA Capture Module Low Byte
Bit
7
6
5
4
3
2
1
0
PCA0CPn[7:0]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Addresses: PCA0CPL0 = 0xFB, PCA0CPL1 = 0xE9, PCA0CPL2 = 0xEB,
SFR Pages: PCA0CPL0 = 0, PCA0CPL1 = 0, PCA0CPL2 = 0,
Bit Name Function
7:0 PCA0CPn[7:0] PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
This register address also allows access to the low byte of the corresponding
PCA channel’s auto-reload value for 9, 10, or 11-bit PWM mode. The ARSEL bit
in register PCA0PWM controls which register is accessed.
Note: A write to this register will clear the module’s ECOMn bit to a 0.
SFR Definition 32.8. PCA0CPHn: PCA Capture Module High Byte
Bit
7
6
5
4
3
2
1
0
PCA0CPn[15:8]
Name
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Addresses: PCA0CPH0 = 0xFC, PCA0CPH1 = 0xEA, PCA0CPH2 = 0xEC,
SFR Pages: PCA0CPH0 = 0, PCA0CPH1 = 0, PCA0CPH2 = 0,
Bit Name Function
7:0 PCA0CPn[15:8] PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
This register address also allows access to the high byte of the corresponding
PCA channel’s auto-reload value for 9, 10, or 11-bit PWM mode. The ARSEL bit in
register PCA0PWM controls which register is accessed.
Note: A write to this register will set the module’s ECOMn bit to a 1.
284
Rev. 0.2
C8051F70x/71x
33. C2 Interface
C8051F70x/71x devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow Flash pro-
gramming and in-system debugging with the production part installed in the end application. The C2 inter-
face operates using only two pins: a bi-directional data signal (C2D), and a clock input (C2CK). See the C2
Interface Specification for details on the C2 protocol.
33.1. C2 Interface Registers
The following describes the C2 registers necessary to perform Flash programming functions through the
C2 interface. All C2 registers are accessed through the C2 interface as described in the C2 Interface Spec-
ification.
C2 Register Definition 33.1. C2ADD: C2 Address
Bit
7
6
5
4
3
2
1
0
C2ADD[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
Bit
Name
Function
7:0 C2ADD[7:0] C2 Address.
The C2ADD register is accessed via the C2 interface to select the target Data register
for C2 Data Read and Data Write commands.
Address Name
Description
0x00
0x01
0x02
0xBF
0x96
0x97
0x91
0xD9
0x95
0x94
DEVICEID
Selects the Device ID Register (read only)
Selects the Revision ID Register (read only)
Selects the C2 Flash Programming Control Register
Selects the C2 Flash Data Register
REVID
FPCTL
FPDAT
CRC0AUTO* Selects the CRC0AUTO Register
CRC0CNT*
CRC0CN*
Selects the CRC0CNT Register
Selects the CRC0CN Register
CRC0DATA* Selects the CRC0DATA Register
CRC0FLIP* Selects the CRC0FLIP Register
CRC0IN*
Selects the CRC0IN Register
Note: CRC registers and functions are described in Section “27. Cyclic Redundancy Check Unit (CRC0)” on
page 194.
Rev. 0.2
285
C8051F70x/71x
C2 Register Definition 33.2. DEVICEID: C2 Device ID
Bit
7
6
5
4
3
2
1
0
DEVICEID[7:0]
R/W
Name
Type
Reset
1
1
1
0
0
0
0
1
C2 Address: 0x00
Bit Name
7:0 DEVICEID[7:0] Device ID.
This read-only register returns the 8-bit device ID: 0xE1 (C8051F70x/71x).
Function
C2 Register Definition 33.3. REVID: C2 Revision ID
Bit
7
6
5
4
3
2
1
0
REVID[7:0]
R/W
Name
Type
Reset
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
C2 Address: 0x01
Bit Name
7:0 REVID[7:0] Revision ID.
Function
This read-only register returns the 8-bit revision ID. For example: 0x00 = Revision A.
286
Rev. 0.2
C8051F70x/71x
C2 Register Definition 33.4. FPCTL: C2 Flash Programming Control
Bit
7
6
5
4
3
2
1
0
FPCTL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0x02
Bit Name
7:0 FPCTL[7:0] C2 Flash Programming Control Register.
Function
This register is used to enable Flash programming via the C2 interface. To enable C2
Flash programming, the following codes must be written in order: 0x02, 0x01. Once
C2 Flash programming is enabled, a system reset must be issued to resume normal
operation.
C2 Register Definition 33.5. FPDAT: C2 Flash Programming Data
Bit
7
6
5
4
3
2
1
0
FPDAT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xBF
Bit Name
7:0 FPDAT[7:0] C2 Flash Programming Data Register.
Function
This register is used to pass Flash commands, addresses, and data during C2 Flash
accesses. Valid commands are listed below.
Code
0x06
0x07
0x08
0x03
Command
Flash Block Read
Flash Block Write
Flash Page Erase
Device Erase
Rev. 0.2
287
C8051F70x/71x
33.2. C2CK Pin Sharing
The C2CK pin is shared with the RST signal on this device family. If the RST pin is used by other parts of
the system, debugging and programming the device can still be accomplished without disrupting the rest of
the system. If this is desired, it is normally necessary to add a resistor to isolate the system’s reset line
from the C2CK signal. This external resistors would not be necessary for production boards, where debug-
ging capabilities are not needed. A typical isolation configuration is shown in Figure 33.1.
Reset
C2CK
C2D
C2 Interface Master
Figure 33.1. Typical C2CK Pin Sharing
The configuration in Figure 33.1 assumes the RST pin on the target device is used as an input only. Addi-
tional resistors may be necessary depending on the specific application.
288
Rev. 0.2
C8051F70x/71x
NOTES:
Rev. 0.2
289
C8051F70x/71x
CONTACT INFORMATION
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290
Rev. 0.2
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