C8051T610 [SILICON]
Mixed-Signal Byte-Programmable EPROM MCU;
| 型号： | C8051T610 |
| 厂家： | 
SILICON |
| 描述： | Mixed-Signal Byte-Programmable EPROM MCU 可编程只读存储器 电动程控只读存储器 |
| 文件： | 总219页 (文件大小：1258K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
C8051T610/1/2/3/4/5/6/7
Mixed-Signal Byte-Programmable EPROM MCU
High-Speed 8051 µC Core
Analog Peripherals
-
10-Bit ADC (‘T610/1/2/3/6 only)
-
Pipelined instruction architecture; executes 70% of
instructions in 1 or 2 system clocks
•
•
Up to 500 ksps
Up to 21, 17, or 13 external inputs
VREF from external pin, Internal Regulator or VDD
-
-
Up to 25 MIPS throughput with 25 MHz clock
Expanded interrupt handler
•
•
•
Internal or external start of conversion source
Built-in temperature sensor
Digital Peripherals
-
Comparators
-
29/25/21 Port I/O with high sink current capability
•
•
•
•
Programmable hysteresis and response time
-
Hardware enhanced UART, SMBus™, and
enhanced SPI™ serial ports
Configurable as interrupt sources
Configurable as reset source (Comparator 0)
Low current (<0.5 µA)
-
-
Four general purpose 16-bit counter/timers
16-Bit programmable counter array (PCA) with five
capture/compare modules and PWM functionality
On-Chip Debug
-
-
-
C8051F310 can be used as code development
platform; Complete development kit available
On-chip debug circuitry facilitates full speed,
non-intrusive in-system debug
Clock Sources
-
Internal oscillator: 24.5 MHz with ±2% accuracy
supports crystal-less UART operation
Provides breakpoints, single stepping,
inspect/modify memory and registers
-
-
External oscillator: RC, C, or CMOS Clock
Can switch between clock sources on-the-fly; useful
in power saving modes
Supply Voltage 1.8 to 3.6 V
-
On-chip LDO for internal core supply
Packages
-
Built-in voltage supply monitor
-
-
-
32-pin LQFP (C8051T610/2/4)
28-pin QFN (C8051T611/3/5)
24-pin QFN (C8051T616/7)
Memory
-
1280 Bytes internal data RAM (256 + 1024)
-
16 or 8 kB byte-programmable EPROM code mem-
ory
Temperature Range: –40 to +85 °C
ANALOG
DIGITAL I/O
PERIPHERALS
UART
Port 0
SMBus
A
M
U
X
10-bit
+
Port 1
Port 2
Port 3
SPI
500 ksps
-
PCA
ADC
+
Timer 0
Timer 1
Timer 2
Timer 3
-
TEMP
SENSOR
VOLTAGE
COMPARATORS
C8051T610/1/2/3/6 only
PROGRAMMABLE PRECISION INTERNAL
OSCILLATOR
HIGH-SPEED CONTROLLER CORE
16 kB/8 kB
EPROM
8051 CPU
(25MIPS)
DEBUG
1280 B
SRAM
14
POR WDT
INTERRUPTS
CIRCUITRY
Rev 1.1 6/11
Copyright © 2011 by Silicon Laboratories
C8051T610/1/2/3/4/5/6/7
C8051T610/1/2/3/4/5/6/7
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C8051T610/1/2/3/4/5/6/7
Table of Contents
1. System Overview ..................................................................................................... 15
2. Ordering Information............................................................................................... 19
3. Pin Definitions.......................................................................................................... 20
4. LQFP-32 Package Specifications ........................................................................... 25
5. QFN-28 Package Specifications ............................................................................. 27
6. QFN-24 Package Specifications ............................................................................. 29
7. Electrical Characteristics........................................................................................ 31
7.1. Absolute Maximum Specifications..................................................................... 31
7.2. Electrical Characteristics ................................................................................... 32
7.3. Typical Performance Curves ............................................................................. 38
8. 10-Bit ADC (ADC0, C8051T610/1/2/3/6 only).......................................................... 39
8.1. Output Code Formatting.................................................................................... 40
8.2. 8-Bit Mode ......................................................................................................... 40
8.3. Modes of Operation........................................................................................... 40
8.3.1. Starting a Conversion................................................................................ 40
8.3.2. Tracking Modes......................................................................................... 41
8.3.3. Settling Time Requirements...................................................................... 42
8.4. Programmable Window Detector....................................................................... 46
8.4.1. Window Detector Example........................................................................ 48
8.5. ADC0 Analog Multiplexer (C8051T610/1/2/3/6 only)......................................... 49
9. Temperature Sensor (C8051T610/1/2/3/6 only) ..................................................... 51
9.1. Calibration ......................................................................................................... 51
10. Voltage Reference Options................................................................................... 54
11. Voltage Regulator (REG0)..................................................................................... 56
12. Comparator0 and Comparator1............................................................................ 58
12.1. Comparator Multiplexers ................................................................................. 65
13. CIP-51 Microcontroller........................................................................................... 68
13.1. Instruction Set.................................................................................................. 69
13.1.1. Instruction and CPU Timing .................................................................... 69
13.2. CIP-51 Register Descriptions .......................................................................... 74
14. Memory Organization ............................................................................................ 77
14.1. Program Memory............................................................................................. 78
14.2. Data Memory................................................................................................... 78
14.2.1. Internal RAM ........................................................................................... 78
14.2.1.1. General Purpose Registers ............................................................ 79
14.2.1.2. Bit Addressable Locations .............................................................. 79
14.2.1.3. Stack ............................................................................................ 79
14.2.2. External RAM.......................................................................................... 79
15. Special Function Registers................................................................................... 81
16. Interrupts ................................................................................................................ 85
16.1. MCU Interrupt Sources and Vectors................................................................ 86
16.1.1. Interrupt Priorities.................................................................................... 86
16.1.2. Interrupt Latency ..................................................................................... 86
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16.2. Interrupt Register Descriptions........................................................................ 87
16.3. External Interrupts INT0 and INT1................................................................... 92
17. EPROM Memory..................................................................................................... 94
17.1. Programming and Reading the EPROM Memory ........................................... 94
17.1.1. EPROM Write Procedure........................................................................ 94
17.1.2. EPROM Read Procedure........................................................................ 95
17.2. Security Options .............................................................................................. 95
17.3. Program Memory CRC.................................................................................... 96
17.3.1. Performing 32-bit CRCs on Full EPROM Content .................................. 96
17.3.2. Performing 16-bit CRCs on 256-Byte EPROM Blocks............................ 96
18. Power Management Modes................................................................................... 97
18.1. Idle Mode......................................................................................................... 97
18.2. Stop Mode ....................................................................................................... 98
19. Reset Sources...................................................................................................... 100
19.1. Power-On Reset............................................................................................ 101
19.2. Power-Fail Reset/VDD Monitor ..................................................................... 102
19.3. External Reset............................................................................................... 103
19.4. Missing Clock Detector Reset ....................................................................... 103
19.5. Comparator0 Reset ....................................................................................... 104
19.6. PCA Watchdog Timer Reset ......................................................................... 104
19.7. EPROM Error Reset...................................................................................... 104
19.8. Software Reset.............................................................................................. 104
20. Oscillators and Clock Selection ......................................................................... 106
20.1. System Clock Selection................................................................................. 106
20.2. Programmable Internal High-Frequency (H-F) Oscillator.............................. 108
20.3. External Oscillator Drive Circuit..................................................................... 110
20.3.1. External RC Example............................................................................ 112
20.3.2. External Capacitor Example.................................................................. 112
21. Port Input/Output ................................................................................................. 113
21.1. Port I/O Modes of Operation.......................................................................... 114
21.1.1. Port Pins Configured for Analog I/O...................................................... 114
21.1.2. Port Pins Configured For Digital I/O...................................................... 114
21.1.3. Interfacing Port I/O to 5V Logic............................................................. 115
21.2. Assigning Port I/O Pins to Analog and Digital Functions............................... 116
21.2.1. Assigning Port I/O Pins to Analog Functions ........................................ 116
21.2.2. Assigning Port I/O Pins to Digital Functions.......................................... 116
21.2.3. Assigning Port I/O Pins to INT0 or INT1 external interrupts.................. 117
21.3. Priority Crossbar Decoder ............................................................................. 117
21.4. Port I/O Initialization ...................................................................................... 121
21.5. Special Function Registers for Accessing and Configuring Port I/O ............. 124
22. SMBus................................................................................................................... 132
22.1. Supporting Documents.................................................................................. 133
22.2. SMBus Configuration..................................................................................... 133
22.3. SMBus Operation .......................................................................................... 133
22.3.1. Transmitter Vs. Receiver....................................................................... 134
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22.3.2. Arbitration.............................................................................................. 134
22.3.3. Clock Low Extension............................................................................. 134
22.3.4. SCL Low Timeout.................................................................................. 134
22.3.5. SCL High (SMBus Free) Timeout ......................................................... 135
22.4. Using the SMBus........................................................................................... 135
22.4.1. SMBus Configuration Register.............................................................. 135
22.4.2. SMB0CN Control Register .................................................................... 139
22.4.3. Data Register ........................................................................................ 142
22.5. SMBus Transfer Modes................................................................................. 143
22.5.1. Write Sequence (Master) ...................................................................... 143
22.5.2. Read Sequence (Master)...................................................................... 144
22.5.3. Write Sequence (Slave) ........................................................................ 145
22.5.4. Read Sequence (Slave)........................................................................ 146
22.6. SMBus Status Decoding................................................................................ 146
23. UART0................................................................................................................... 149
23.1. Enhanced Baud Rate Generation.................................................................. 150
23.2. Operational Modes ........................................................................................ 151
23.2.1. 8-Bit UART............................................................................................ 151
23.2.2. 9-Bit UART............................................................................................ 152
23.3. Multiprocessor Communications ................................................................... 153
24. Enhanced Serial Peripheral Interface (SPI0) ..................................................... 157
24.1. Signal Descriptions........................................................................................ 158
24.1.1. Master Out, Slave In (MOSI)................................................................. 158
24.1.2. Master In, Slave Out (MISO)................................................................. 158
24.1.3. Serial Clock (SCK) ................................................................................ 158
24.1.4. Slave Select (NSS) ............................................................................... 158
24.2. SPI0 Master Mode Operation........................................................................ 159
24.3. SPI0 Slave Mode Operation.......................................................................... 160
24.4. SPI0 Interrupt Sources .................................................................................. 161
24.5. Serial Clock Phase and Polarity .................................................................... 161
24.6. SPI Special Function Registers..................................................................... 163
25. Timers ................................................................................................................... 170
25.1. Timer 0 and Timer 1 ...................................................................................... 172
25.1.1. Mode 0: 13-bit Counter/Timer ............................................................... 172
25.1.2. Mode 1: 16-bit Counter/Timer ............................................................... 173
25.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload..................................... 174
25.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................ 175
25.2. Timer 2 .......................................................................................................... 180
25.2.1. 16-bit Timer with Auto-Reload............................................................... 180
25.2.2. 8-bit Timers with Auto-Reload............................................................... 181
25.3. Timer 3 .......................................................................................................... 185
25.3.1. 16-bit Timer with Auto-Reload............................................................... 185
25.3.2. 8-bit Timers with Auto-Reload............................................................... 186
26. Programmable Counter Array............................................................................. 190
26.1. PCA Counter/Timer ....................................................................................... 191
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26.2. PCA0 Interrupt Sources................................................................................. 192
26.3. Capture/Compare Modules ........................................................................... 193
26.3.1. Edge-triggered Capture Mode............................................................... 194
26.3.2. Software Timer (Compare) Mode.......................................................... 195
26.3.3. High-Speed Output Mode ..................................................................... 196
26.3.4. Frequency Output Mode ....................................................................... 197
26.3.5. 8-bit Pulse Width Modulator Mode....................................................... 198
26.3.6. 16-Bit Pulse Width Modulator Mode..................................................... 199
26.4. Watchdog Timer Mode .................................................................................. 200
26.4.1. Watchdog Timer Operation................................................................... 200
26.4.2. Watchdog Timer Usage ........................................................................ 201
26.5. Register Descriptions for PCA0..................................................................... 203
27. C2 Interface .......................................................................................................... 208
27.1. C2 Interface Registers................................................................................... 208
27.2. C2 Pin Sharing .............................................................................................. 215
Document Change List.............................................................................................. 216
Contact Information................................................................................................... 218
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List of Figures
1. System Overview
Figure 1.1. C8051T610/2/4 Block Diagram (32-pin LQFP) ..................................... 16
Figure 1.2. C8051T611/3/5 Block Diagram (28-pin QFN) ....................................... 17
Figure 1.3. C8051T616/7 Block Diagram (24-pin QFN) .......................................... 18
3. Pin Definitions
Figure 3.1. LQFP-32 Pinout Diagram (Top View) .................................................... 22
Figure 3.2. QFN-28 Pinout Diagram (Top View) ..................................................... 23
Figure 3.3. QFN-24 Pinout Diagram (Top View) ..................................................... 24
4. LQFP-32 Package Specifications
Figure 4.1. LQFP-32 Package Drawing ................................................................... 25
Figure 4.2. LQFP-32 Recommended PCB Land Pattern ........................................ 26
5. QFN-28 Package Specifications
Figure 5.1. QFN-28 Package Drawing .................................................................... 27
Figure 5.2. QFN-28 Recommended PCB Land Pattern .......................................... 28
6. QFN-24 Package Specifications
Figure 6.1. QFN-24 Package Drawing .................................................................... 29
Figure 6.2. QFN-24 Recommended PCB Land Pattern .......................................... 30
7. Electrical Characteristics
Figure 7.1. Normal Mode Digital Supply Current vs. Frequency (MPCE = 1) ......... 38
Figure 7.2. Idle Mode Digital Supply Current vs. Frequency (MPCE = 1) ............... 38
8. 10-Bit ADC (ADC0, C8051T610/1/2/3/6 only)
Figure 8.1. ADC0 Functional Block Diagram ........................................................... 39
Figure 8.2. 10-Bit ADC Track and Conversion Example Timing ............................. 41
Figure 8.3. ADC0 Equivalent Input Circuits ............................................................. 42
Figure 8.4. ADC Window Compare Example: Right-Justified Data ......................... 48
Figure 8.5. ADC Window Compare Example: Left-Justified Data ........................... 48
Figure 8.6. ADC0 Multiplexer Block Diagram .......................................................... 49
9. Temperature Sensor (C8051T610/1/2/3/6 only)
Figure 9.1. Temperature Sensor Transfer Function ................................................ 51
Figure 9.2. Temperature Sensor Error with 1-Point Calibration at 0 Celsius ........... 52
10. Voltage Reference Options
Figure 10.1. Voltage Reference Functional Block Diagram ..................................... 54
12. Comparator0 and Comparator1
Figure 12.1. Comparator0 Functional Block Diagram ............................................. 58
Figure 12.2. Comparator1 Functional Block Diagram ............................................. 59
Figure 12.3. Comparator Hysteresis Plot ................................................................ 60
Figure 12.4. Comparator Input Multiplexer Block Diagram ...................................... 65
13. CIP-51 Microcontroller
Figure 13.1. CIP-51 Block Diagram ......................................................................... 68
14. Memory Organization
Figure 14.1. Memory Map ....................................................................................... 77
Figure 14.2. Program Memory Map ......................................................................... 78
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19. Reset Sources
Figure 19.1. Reset Sources ................................................................................... 100
Figure 19.2. Power-On and VDD Monitor Reset Timing ....................................... 101
20. Oscillators and Clock Selection
Figure 20.1. Oscillator Options .............................................................................. 106
21. Port Input/Output
Figure 21.1. Port I/O Functional Block Diagram .................................................... 113
Figure 21.2. Port I/O Cell Block Diagram .............................................................. 115
Figure 21.3. Priority Crossbar Decoder Potential Pin Assignments ...................... 118
Figure 21.4. Priority Crossbar Decoder Example 1 - No Skipped Pins ................. 119
Figure 21.5. Priority Crossbar Decoder Example 2 - Skipping Pins ...................... 120
22. SMBus
Figure 22.1. SMBus Block Diagram ...................................................................... 132
Figure 22.2. Typical SMBus Configuration ............................................................ 133
Figure 22.3. SMBus Transaction ........................................................................... 134
Figure 22.4. Typical SMBus SCL Generation ........................................................ 136
Figure 22.5. Typical Master Write Sequence ........................................................ 143
Figure 22.6. Typical Master Read Sequence ........................................................ 144
Figure 22.7. Typical Slave Write Sequence .......................................................... 145
Figure 22.8. Typical Slave Read Sequence .......................................................... 146
23. UART0
Figure 23.1. UART0 Block Diagram ...................................................................... 149
Figure 23.2. UART0 Baud Rate Logic ................................................................... 150
Figure 23.3. UART Interconnect Diagram ............................................................. 151
Figure 23.4. 8-Bit UART Timing Diagram .............................................................. 151
Figure 23.5. 9-Bit UART Timing Diagram .............................................................. 152
Figure 23.6. UART Multi-Processor Mode Interconnect Diagram ......................... 153
24. Enhanced Serial Peripheral Interface (SPI0)
Figure 24.1. SPI Block Diagram ............................................................................ 157
Figure 24.2. Multiple-Master Mode Connection Diagram ...................................... 159
Figure 24.3. 3-Wire Single Master and 3-Wire Single Slave Mode
Connection Diagram ........................................................................................ 160
Figure 24.4. 4-Wire Single Master Mode and 4-Wire Slave Mode
Connection Diagram ........................................................................................ 160
Figure 24.5. Master Mode Data/Clock Timing ....................................................... 162
Figure 24.6. Slave Mode Data/Clock Timing (CKPHA = 0) ................................... 162
Figure 24.7. Slave Mode Data/Clock Timing (CKPHA = 1) ................................... 163
Figure 24.8. SPI Master Timing (CKPHA = 0) ....................................................... 167
Figure 24.9. SPI Master Timing (CKPHA = 1) ....................................................... 167
Figure 24.10. SPI Slave Timing (CKPHA = 0) ....................................................... 168
Figure 24.11. SPI Slave Timing (CKPHA = 1) ....................................................... 168
25. Timers
Figure 25.1. T0 Mode 0 Block Diagram ................................................................. 173
Figure 25.2. T0 Mode 2 Block Diagram ................................................................. 174
Figure 25.3. T0 Mode 3 Block Diagram ................................................................. 175
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Figure 25.4. Timer 2 16-Bit Mode Block Diagram ................................................. 180
Figure 25.5. Timer 2 8-Bit Mode Block Diagram ................................................... 181
Figure 25.6. Timer 3 16-Bit Mode Block Diagram ................................................. 185
Figure 25.7. Timer 3 8-Bit Mode Block Diagram ................................................... 186
26. Programmable Counter Array
Figure 26.1. PCA Block Diagram ........................................................................... 190
Figure 26.2. PCA Counter/Timer Block Diagram ................................................... 191
Figure 26.3. PCA Interrupt Block Diagram ............................................................ 192
Figure 26.4. PCA Capture Mode Diagram ............................................................. 194
Figure 26.5. PCA Software Timer Mode Diagram ................................................. 195
Figure 26.6. PCA High-Speed Output Mode Diagram ........................................... 196
Figure 26.7. PCA Frequency Output Mode ........................................................... 197
Figure 26.8. PCA 8-Bit PWM Mode Diagram ........................................................ 198
Figure 26.9. PCA 16-Bit PWM Mode ..................................................................... 199
Figure 26.10. PCA Module 4 with Watchdog Timer Enabled ................................ 200
27. C2 Interface
Figure 27.1. Typical C2 Pin Sharing ...................................................................... 215
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List of Tables
2. Ordering Information
Table 2.1. Product Selection Guide ......................................................................... 19
3. Pin Definitions
Table 3.1. Pin Definitions for the C8051T610/1/2/3/4/5/6/7 ..................................... 20
4. LQFP-32 Package Specifications
Table 4.1. LQFP-32 Package Dimensions .............................................................. 25
Table 4.2. LQFP-32 PCB Land Pattern Dimesions ................................................. 26
5. QFN-28 Package Specifications
Table 5.1. QFN-28 Package Dimensions ................................................................ 27
Table 5.2. QFN-28 PCB Land Pattern Dimesions ................................................... 28
6. QFN-24 Package Specifications
Table 6.1. QFN-24 Package Dimensions ................................................................ 29
Table 6.2. QFN-24 PCB Land Pattern Dimesions ................................................... 30
7. Electrical Characteristics
Table 7.1. Absolute Maximum Ratings .................................................................... 31
Table 7.2. Global Electrical Characteristics ............................................................. 32
Table 7.3. Port I/O DC Electrical Characteristics ..................................................... 33
Table 7.4. Reset Electrical Characteristics .............................................................. 34
Table 7.5. Internal Voltage Regulator Electrical Characteristics ............................. 34
Table 7.6. EPROM Electrical Characteristics .......................................................... 34
Table 7.7. Internal High-Frequency Oscillator Electrical Characteristics ................. 35
Table 7.8. ADC0 Electrical Characteristics .............................................................. 35
Table 7.9. Temperature Sensor Electrical Characteristics ...................................... 36
Table 7.10. Voltage Reference Electrical Characteristics ....................................... 36
Table 7.11. Comparator Electrical Characteristics .................................................. 37
13. CIP-51 Microcontroller
Table 13.1. CIP-51 Instruction Set Summary .......................................................... 70
15. Special Function Registers
Table 15.1. Special Function Register (SFR) Memory Map .................................... 81
Table 15.2. Special Function Registers ................................................................... 82
16. Interrupts
Table 16.1. Interrupt Summary ................................................................................ 87
17. EPROM Memory
Table 17.1. Security Byte Decoding ........................................................................ 95
21. Port Input/Output
Table 21.1. Port I/O Assignment for Analog Functions ......................................... 116
Table 21.2. Port I/O Assignment for Digital Functions ........................................... 116
Table 21.3. Port I/O Assignment for INT0 and INT1 Functions ............................. 117
22. SMBus
Table 22.1. SMBus Clock Source Selection .......................................................... 136
Table 22.2. Minimum SDA Setup and Hold Times ................................................ 137
Table 22.3. Sources for Hardware Changes to SMB0CN ..................................... 141
Table 22.4. SMBus Status Decoding ..................................................................... 147
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23. UART0
Table 23.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator .............................................. 156
Table 23.2. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator ......................................... 156
24. Enhanced Serial Peripheral Interface (SPI0)
Table 24.1. SPI Slave Timing Parameters ............................................................ 169
26. Programmable Counter Array
Table 26.1. PCA Timebase Input Options ............................................................. 191
Table 26.2. PCA0CPM Bit Settings for PCA Capture/Compare Modules ............. 193
Table 26.3. Watchdog Timer Timeout Intervals1 ................................................... 202
27. C2 Interface
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List of Registers
SFR Definition 8.1. ADC0CF: ADC0 Configuration ...................................................... 43
SFR Definition 8.2. ADC0H: ADC0 Data Word MSB .................................................... 44
SFR Definition 8.3. ADC0L: ADC0 Data Word LSB ...................................................... 44
SFR Definition 8.4. ADC0CN: ADC0 Control ................................................................ 45
SFR Definition 8.5. ADC0GTH: ADC0 Greater-Than Data High Byte .......................... 46
SFR Definition 8.6. ADC0GTL: ADC0 Greater-Than Data Low Byte ............................ 46
SFR Definition 8.7. ADC0LTH: ADC0 Less-Than Data High Byte ................................ 47
SFR Definition 8.8. ADC0LTL: ADC0 Less-Than Data Low Byte ................................. 47
SFR Definition 8.9. AMX0P: AMUX0 Positive Channel Select ..................................... 50
SFR Definition 9.1. TOFFH: Temperature Offset Measurement High Byte .................. 53
SFR Definition 9.2. TOFFL: Temperature Offset Measurement Low Byte ................... 53
SFR Definition 10.1. REF0CN: Reference Control ....................................................... 55
SFR Definition 11.1. REG0CN: Voltage Regulator Control .......................................... 57
SFR Definition 12.1. CPT0CN: Comparator0 Control ................................................... 61
SFR Definition 12.2. CPT0MD: Comparator0 Mode Selection ..................................... 62
SFR Definition 12.3. CPT1CN: Comparator1 Control ................................................... 63
SFR Definition 12.4. CPT1MD: Comparator1 Mode Selection ..................................... 64
SFR Definition 12.5. CPT0MX: Comparator0 MUX Selection ...................................... 66
SFR Definition 12.6. CPT1MX: Comparator1 MUX Selection ...................................... 67
SFR Definition 13.1. DPL: Data Pointer Low Byte ........................................................ 74
SFR Definition 13.2. DPH: Data Pointer High Byte ....................................................... 74
SFR Definition 13.3. SP: Stack Pointer ......................................................................... 75
SFR Definition 13.4. ACC: Accumulator ....................................................................... 75
SFR Definition 13.5. B: B Register ................................................................................ 75
SFR Definition 13.6. PSW: Program Status Word ........................................................ 76
SFR Definition 14.1. EMI0CN: External Memory Interface Control .............................. 80
SFR Definition 16.1. IE: Interrupt Enable ...................................................................... 88
SFR Definition 16.2. IP: Interrupt Priority ...................................................................... 89
SFR Definition 16.3. EIE1: Extended Interrupt Enable 1 .............................................. 90
SFR Definition 16.4. EIP1: Extended Interrupt Priority 1 .............................................. 91
SFR Definition 16.5. IT01CF: INT0/INT1 Configuration ................................................ 93
SFR Definition 18.1. PCON: Power Control .................................................................. 99
SFR Definition 19.1. VDM0CN: VDD Monitor Control ................................................ 103
SFR Definition 19.2. RSTSRC: Reset Source ............................................................ 105
SFR Definition 20.1. CLKSEL: Clock Select ............................................................... 107
SFR Definition 20.2. OSCICL: Internal H-F Oscillator Calibration .............................. 108
SFR Definition 20.3. OSCICN: Internal H-F Oscillator Control ................................... 109
SFR Definition 20.4. OSCXCN: External Oscillator Control ........................................ 111
SFR Definition 21.1. XBR0: Port I/O Crossbar Register 0 .......................................... 122
SFR Definition 21.2. XBR1: Port I/O Crossbar Register 1 .......................................... 123
SFR Definition 21.3. P0: Port 0 ................................................................................... 124
SFR Definition 21.4. P0MDIN: Port 0 Input Mode ....................................................... 125
SFR Definition 21.5. P0MDOUT: Port 0 Output Mode ................................................ 125
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SFR Definition 21.6. P0SKIP: Port 0 Skip ................................................................... 126
SFR Definition 21.7. P1: Port 1 ................................................................................... 126
SFR Definition 21.8. P1MDIN: Port 1 Input Mode ....................................................... 127
SFR Definition 21.9. P1MDOUT: Port 1 Output Mode ................................................ 127
SFR Definition 21.10. P1SKIP: Port 1 Skip ................................................................. 128
SFR Definition 21.11. P2: Port 2 ................................................................................. 128
SFR Definition 21.12. P2MDIN: Port 2 Input Mode ..................................................... 129
SFR Definition 21.13. P2MDOUT: Port 2 Output Mode .............................................. 129
SFR Definition 21.14. P2SKIP: Port 2 Skip ................................................................. 130
SFR Definition 21.15. P3: Port 3 ................................................................................. 130
SFR Definition 21.16. P3MDIN: Port 3 Input Mode ..................................................... 131
SFR Definition 21.17. P3MDOUT: Port 3 Output Mode .............................................. 131
SFR Definition 22.1. SMB0CF: SMBus Clock/Configuration ...................................... 138
SFR Definition 22.2. SMB0CN: SMBus Control .......................................................... 140
SFR Definition 22.3. SMB0DAT: SMBus Data ............................................................ 142
SFR Definition 23.1. SCON0: Serial Port 0 Control .................................................... 154
SFR Definition 23.2. SBUF0: Serial (UART0) Port Data Buffer .................................. 155
SFR Definition 24.1. SPI0CFG: SPI0 Configuration ................................................... 164
SFR Definition 24.2. SPI0CN: SPI0 Control ............................................................... 165
SFR Definition 24.3. SPI0CKR: SPI0 Clock Rate ....................................................... 166
SFR Definition 24.4. SPI0DAT: SPI0 Data ................................................................. 166
SFR Definition 25.1. CKCON: Clock Control .............................................................. 171
SFR Definition 25.2. TCON: Timer Control ................................................................. 176
SFR Definition 25.3. TMOD: Timer Mode ................................................................... 177
SFR Definition 25.4. TL0: Timer 0 Low Byte ............................................................... 178
SFR Definition 25.5. TL1: Timer 1 Low Byte ............................................................... 178
SFR Definition 25.6. TH0: Timer 0 High Byte ............................................................. 179
SFR Definition 25.7. TH1: Timer 1 High Byte ............................................................. 179
SFR Definition 25.8. TMR2CN: Timer 2 Control ......................................................... 182
SFR Definition 25.9. TMR2RLL: Timer 2 Reload Register Low Byte .......................... 183
SFR Definition 25.10. TMR2RLH: Timer 2 Reload Register High Byte ...................... 183
SFR Definition 25.11. TMR2L: Timer 2 Low Byte ....................................................... 183
SFR Definition 25.12. TMR2H Timer 2 High Byte ....................................................... 184
SFR Definition 25.13. TMR3CN: Timer 3 Control ....................................................... 187
SFR Definition 25.14. TMR3RLL: Timer 3 Reload Register Low Byte ........................ 188
SFR Definition 25.15. TMR3RLH: Timer 3 Reload Register High Byte ...................... 188
SFR Definition 25.16. TMR3L: Timer 3 Low Byte ....................................................... 188
SFR Definition 25.17. TMR3H Timer 3 High Byte ....................................................... 189
SFR Definition 26.1. PCA0CN: PCA Control .............................................................. 203
SFR Definition 26.2. PCA0MD: PCA Mode ................................................................ 204
SFR Definition 26.3. PCA0CPMn: PCA Capture/Compare Mode .............................. 205
SFR Definition 26.4. PCA0L: PCA Counter/Timer Low Byte ...................................... 206
SFR Definition 26.5. PCA0H: PCA Counter/Timer High Byte ..................................... 206
SFR Definition 26.6. PCA0CPLn: PCA Capture Module Low Byte ............................. 207
SFR Definition 26.7. PCA0CPHn: PCA Capture Module High Byte ........................... 207
Rev 1.1
13
C8051T610/1/2/3/4/5/6/7
C2 Register Definition 27.1. C2ADD: C2 Address ...................................................... 208
C2 Register Definition 27.2. DEVICEID: C2 Device ID ............................................... 209
C2 Register Definition 27.3. REVID: C2 Revision ID .................................................. 209
C2 Register Definition 27.4. DEVCTL: C2 Device Control .......................................... 210
C2 Register Definition 27.5. EPCTL: EPROM Programming Control Register ........... 210
C2 Register Definition 27.6. EPDAT: C2 EPROM Data .............................................. 211
C2 Register Definition 27.7. EPSTAT: C2 EPROM Status ......................................... 211
C2 Register Definition 27.8. EPADDRH: C2 EPROM Address High Byte .................. 212
C2 Register Definition 27.9. EPADDRL: C2 EPROM Address Low Byte ................... 212
C2 Register Definition 27.10. CRC0: CRC Byte 0 ...................................................... 213
C2 Register Definition 27.11. CRC1: CRC Byte 1 ...................................................... 213
C2 Register Definition 27.12. CRC2: CRC Byte 2 ...................................................... 214
C2 Register Definition 27.13. CRC3: CRC Byte 3 ...................................................... 214
14
Rev 1.1
C8051T610/1/2/3/4/5/6/7
1. System Overview
C8051T610/1/2/3/4/5/6/7 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 num-
bers.
High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
C8051F310 ISP Flash device is available for quick in-system code development
10-bit 500 ksps Single-ended ADC with analog multiplexer and integrated temperature sensor
Precision calibrated 24.5 MHz internal oscillator
16 k or 8 k of on-chip Byte-Programmable EPROM—(512 bytes are reserved on 16k version)
1280 bytes of on-chip RAM
SMBus/I2C, SPI, and Enhanced UART serial interfaces implemented in hardware
Four general-purpose 16-bit timers
Programmable Counter/Timer Array (PCA) with five capture/compare modules and Watchdog Timer function
On-chip Power-On Reset and VDD Monitor
On-chip Voltage Comparators (2)
29/25/21 Port I/O
With on-chip power-on reset,
V
monitor, watchdog timer, and clock oscillator, the
DD
C8051T610/1/2/3/4/5/6/7 devices are truly stand-alone, system-on-a-chip solutions. User software has
complete control of all peripherals and may individually shut down any or all peripherals for power savings.
Code written for the C8051T610/1/2/3/4/5/6/7 family of processors will run on the C8051F310 Mixed-Sig-
nal ISP Flash microcontroller, providing a quick, cost-effective way to develop code without requiring spe-
cial emulator circuitry. The C8051T610/1/2/3/4/5/6/7 processors include Silicon Laboratories’ 2-Wire C2
Debug and Programming interface, which allows non-intrusive (uses no on-chip resources), full speed, in-
circuit debugging using the production MCU installed in the final application. This debug logic supports
inspection 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 debug-
ging 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. The Port I/O and RST pins are tolerant of input
signals up to 5 V. See Table 2.1 for ordering information. Block diagrams of the devices in the
C8051T610/1/2/3/4/5/6/7 family are shown in Figure 1.1, Figure 1.2 and Figure 1.3.
Rev 1.1
15
C8051T610/1/2/3/4/5/6/7
Port I/O Configuration
Power On
Reset
CIP-51 8051
Controller Core
P0.0/VREF
P0.1
Digital Peripherals
Reset
8/16 k Byte EPROM
Program Memory
P0.2/VPP
P0.3/EXTCLK
P0.4/TX
UART
Port 0
Drivers
Debug /
Programming
Hardware
C2CK/RST
Timers 0,
P0.5/RX
P0.6/CNVSTR
P0.7
1, 2, 3
256 byte SRAM
1 k Byte XRAM
Priority
Crossbar
Decoder
WDT
PCA/
C2D
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
SMBus
SPI
Port 1
Drivers
Crossbar Control
Peripheral Power
Regulator
SFR
Bus
SYSCLK
VDD
GND
Analog Peripherals
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Core Power
CP0
+
-
CP1
+
-
Port 2
Drivers
Comparators
VDD
VREF
VDD
EXTCLK
A
M
U
X
External
Clock
Circuit
Precision
Internal
Oscillator
10-bit
500 ksps
ADC
P3.0/C2D
P3.1
P3.2
P3.3
P3.4
Temp
Sensor
Port 3
Drivers
System Clock
Configuration
C8051T610/2 Only
Figure 1.1. C8051T610/2/4 Block Diagram (32-pin LQFP)
16
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Port I/O Configuration
P0.0/VREF
Power On
Reset
CIP-51 8051
Controller Core
Digital Peripherals
P0.1
Reset
8/16 k Byte EPROM
Program Memory
P0.2/VPP
P0.3/EXTCLK
P0.4/TX
UART
Port 0
Drivers
Debug /
Programming
Hardware
C2CK/RST
Timers 0,
P0.5/RX
P0.6/CNVSTR
P0.7
1, 2, 3
256 byte SRAM
1 k Byte XRAM
Priority
Crossbar
PCA/
C2D
Decoder
WDT
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
SMBus
SPI
Port 1
Drivers
Crossbar Control
Peripheral Power
Regulator
SFR
Bus
SYSCLK
VDD
GND
Analog Peripherals
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Core Power
CP0
+
-
CP1
+
-
Port 2
Drivers
Comparators
VDD
VREF
VDD
EXTCLK
A
M
U
X
External
Clock
Precision
Internal
10-bit
500 ksps
ADC
P3.0/C2D
Circuit
Oscillator
Temp
Port 3
Drivers
Sensor
System Clock
Configuration
C8051T611/3 Only
Figure 1.2. C8051T611/3/5 Block Diagram (28-pin QFN)
Rev 1.1
17
C8051T610/1/2/3/4/5/6/7
Port I/O Configuration
Power On
Reset
CIP-51 8051
Controller Core
P0.0/VREF
P0.1
Digital Peripherals
Reset
16 k Byte EPROM
Program Memory
P0.2/VPP
P0.3/EXTCLK
P0.4/TX
UART
Port 0
Drivers
Debug /
Programming
Hardware
C2CK/RST
Timers 0,
P0.5/RX
P0.6/CNVSTR
P0.7
1, 2, 3
256 byte SRAM
1 k Byte XRAM
Priority
Crossbar
Decoder
WDT
PCA/
C2D
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
SMBus
SPI
Port 1
Drivers
Crossbar Control
Peripheral Power
Regulator
SFR
Bus
SYSCLK
VDD
GND
Analog Peripherals
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
Core Power
CP0
+
-
CP1
+
-
Port 2
Drivers
Comparators
VDD
VREF
VDD
EXTCLK
A
M
U
X
External
Clock
Circuit
Precision
Internal
Oscillator
10-bit
500 ksps
ADC
P3.0/C2D
Temp
Port 3
Drivers
Sensor
System Clock
Configuration
C8051T616 Only
Figure 1.3. C8051T616/7 Block Diagram (24-pin QFN)
18
Rev 1.1
C8051T610/1/2/3/4/5/6/7
2. Ordering Information
Table 2.1. Product Selection Guide
C8051T610-GQ
C8051T611-GM
C8051T612-GQ
C8051T613-GM
C8051T614-GQ
C8051T615-GM
C8051T616-GM
C8051T617-GM
25 16k* 1280
25 16k* 1280
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
4
4
4
4
4
4
4
4
Y
Y
Y
Y
Y
Y
Y
Y
29
25
29
25
29
25
21
21
Y
Y
Y
Y
2
2
2
2
2
2
2
2
Y
Y
Y
Y
Y
Y
Y
Y
LQFP-32
QFN-28
LQFP-32
QFN-28
LQFP-32
QFN-28
QFN-24
QFN-24
25 8k
25 8k
25 8k
25 8k
1280
1280
1280
1280
Y
Y
Y
Y
—
—
Y
—
—
Y
25 16k* 1280
25 16k* 1280
—
—
* 512 Bytes Reserved for Factory Use
Rev 1.1
19
C8051T610/1/2/3/4/5/6/7
3. Pin Definitions
Table 3.1. Pin Definitions for the C8051T610/1/2/3/4/5/6/7
Pin
Pin
Pin
Name
Type
Description
T610/2/4 T611/3/5 T616/7
V
4
3
5
4
3
5
4
3
5
Power Supply Voltage.
DD
GND
RST/
Ground.
D I/O
D I/O
Device Reset. Open-drain output of internal POR.
C2CK
P3.0/
Clock signal for the C2 Debug Interface.
6
6
6
D I/O or Port 3.0.
A In
C2D
P0.0
P0.1
P0.2/
D I/O
Bi-directional data signal for the C2 Debug Inter-
face.
2
1
2
1
2
1
D I/O or Port 0.0.
A In
D I/O or Port 0.1.
A In
32
28
24
D I/O or Port 0.2.
A In
VPP
P0.3
A In
VPP Programming Voltage Input.
31
30
29
28
27
26
25
24
23
22
21
20
D I/O or Port 0.3.
A in
P0.4
P0.5
P0.6
D I/O or Port 0.4.
A In
D I/O or Port 0.5.
A In
D I/O or Port 0.6.
A In
P0.7
P1.0
27
26
23
22
19
18
D I/O
Port 0.7.
D I/O or Port 1.0.
A In
P1.1
P1.2
25
24
21
20
17
16
D I/O or Port 1.1.
A In
D I/O or Port 1.2.
A In
20
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Table 3.1. Pin Definitions for the C8051T610/1/2/3/4/5/6/7(Continued)
Pin
Pin
Pin
Name
Type
Description
T610/2/4 T611/3/5 T616/7
P1.3
23
22
21
20
19
18
17
16
15
14
13
12
11
7
19
18
17
16
15
14
13
12
11
10
9
15
14
13
—
—
12
11
10
9
D I/O or Port 1.3.
A In
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.1
P3.2
P3.3
P3.4
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
D I/O or Port 2.0.
A In
D I/O or Port 2.1.
A In
D I/O or Port 2.2.
A In
D I/O or Port 2.3.
A In
8
D I/O or Port 2.4.
A In
7
D I/O or Port 2.5.
A In
8
—
—
—
—
—
—
D I/O or Port 2.6.
A In
7
D I/O or Port 2.7.
A In
—
—
—
—
D I/O or Port 3.1.
A In
8
D I/O or Port 3.2.
A In
9
D I/O or Port 3.3.
A In
10
D I/O or Port 3.4.
A In
Rev 1.1
21
C8051T610/1/2/3/4/5/6/7
P0.1
P0.0
P1.2
23 P1.3
P1.4
1
2
3
4
5
6
7
8
24
GND
22
C8051T610/2/4
Top View
VDD
21 P1.5
P1.6
20
RST/C2CK
P3.0/C2D
P3.1
P1.7
P2.0
19
18
P3.2
17 P2.1
Figure 3.1. LQFP-32 Pinout Diagram (Top View)
22
Rev 1.1
C8051T610/1/2/3/4/5/6/7
P0.1
P0.0
1
2
3
4
5
6
7
21
20
19
18
17
16
15
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
GND
C8051T611/3/5
Top View
VDD
RST/C2CK
P3.0/C2D
P2.7
GND (optional)
Figure 3.2. QFN-28 Pinout Diagram (Top View)
Rev 1.1
23
C8051T610/1/2/3/4/5/6/7
P0.1
P0.0
1
2
3
4
5
6
18
17
16
15
14
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
GND
C8051T616/7
Top View
VDD
RST/C2CK
P3.0 / C2D
GND (optional)
13
Figure 3.3. QFN-24 Pinout Diagram (Top View)
24
Rev 1.1
C8051T610/1/2/3/4/5/6/7
4. LQFP-32 Package Specifications
Figure 4.1. LQFP-32 Package Drawing
Table 4.1. LQFP-32 Package Dimensions
Dimension
Min
Typ
Max
Dimension
Min
Typ
Max
A
—
—
—
1.60
0.15
1.45
0.45
0.20
E
E1
L
9.00 BSC.
7.00 BSC.
0.60
A1
0.05
1.35
0.30
0.09
A2
1.40
0.45
0.75
b
0.37
aaa
bbb
ccc
ddd
0.20
c
D
—
0.20
9.00 BSC.
7.00 BSC.
0.80 BSC.
0.10
D1
0.20
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 BBA.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small
Body Components.
Rev 1.1
25
C8051T610/1/2/3/4/5/6/7
Figure 4.2. LQFP-32 Recommended PCB Land Pattern
Table 4.2. LQFP-32 PCB Land Pattern Dimesions
Dimension
Min
Max
Dimension
Min
Max
C1
C2
E
8.40
8.40
8.50
8.50
X1
Y1
0.40
1.25
0.50
1.35
0.80
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 pads.
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-020C specification for
Small Body Components.
26
Rev 1.1
C8051T610/1/2/3/4/5/6/7
5. QFN-28 Package Specifications
Figure 5.1. QFN-28 Package Drawing
Table 5.1. QFN-28 Package Dimensions
Dimension
Min
Typ
Max
Dimension
Min
Typ
Max
A
0.80
0.00
0.90
0.02
1.00
0.05
L
0.35
0.00
0.55
—
0.65
0.15
A1
L1
A3
0.25 REF
0.23
aaa
bbb
ddd
eee
Z
0.15
0.10
0.05
0.08
0.44
0.18
b
0.18
2.90
0.30
3.35
D
D2
5.00 BSC.
3.15
e
0.50 BSC.
5.00 BSC.
3.15
E
Y
E2
2.90
3.35
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation VHHD except for
custom features D2, E2, Z, Y, and L which are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small
Body Components.
Rev 1.1
27
C8051T610/1/2/3/4/5/6/7
Figure 5.2. QFN-28 Recommended PCB Land Pattern
Table 5.2. QFN-28 PCB Land Pattern Dimesions
Dimension
Min
Max
Dimension
Min
Max
C1
C2
E
4.80
4.80
0.50
X2
Y1
Y2
3.20
0.85
3.20
3.30
0.95
3.30
X1
0.20
0.30
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 the IPC-7351 guidelines.
Solder Mask Design
4. 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
5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used
to assure good solder paste release.
6. The stencil thickness should be 0.125mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
8. A 3x3 array of 0.90mm openings on a 1.1mm pitch should be used for the center pad to
assure the proper paste volume.
Card Assembly
9. A No-Clean, Type-3 solder paste is recommended.
10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for
Small Body Components.
28
Rev 1.1
C8051T610/1/2/3/4/5/6/7
6. QFN-24 Package Specifications
Figure 6.1. QFN-24 Package Drawing
Table 6.1. QFN-24 Package Dimensions
Dimension
Min
Typ
Max
Dimension
Min
Typ
Max
A
0.70
0.00
0.18
0.75
0.02
0.80
0.05
0.30
L
0.30
0.00
—
0.40
—
0.50
0.15
0.15
0.10
0.05
0.08
—
A1
L1
b
D
0.25
aaa
bbb
ddd
eee
Z
—
4.00 BSC.
2.70
—
—
D2
2.55
2.55
2.80
2.80
—
—
e
0.50 BSC.
4.00 BSC.
2.70
—
—
E
—
0.24
0.18
E2
Y
—
—
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 Solid State Outline MO-220, variation WGGD except for
custom features D2, E2, Z, Y, and L which are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small
Body Components.
Rev 1.1
29
C8051T610/1/2/3/4/5/6/7
Figure 6.2. QFN-24 Recommended PCB Land Pattern
Table 6.2. QFN-24 PCB Land Pattern Dimesions
Dimension
Min
Max
Dimension
Min
Max
C1
C2
E
3.90
3.90
4.00
4.00
X2
Y1
Y2
2.70
0.65
2.70
2.80
0.75
2.80
0.50 BSC
X1
0.20
0.30
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 pads.
7. A 2x2 array of 1.10mm x 1.10mm openings on a 1.30mm pitch should be used for the center
pad.
Card Assembly
8. A No-Clean, Type-3 solder paste is recommended.
9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for
Small Body Components.
30
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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
—
—
125
150
5.8
°C
°C
Voltage on RST or any Port I/O Pin
V
V
> 2.2 V
< 2.2 V
–0.3
–0.3
—
—
V
V
DD
DD
(except V during programming) with
V
+ 3.6
PP
DD
respect to GND
Voltage on V with respect to GND
during a programming operation
VDD > 2.4 V
–0.3
—
—
—
7.0
10
V
s
PP
Duration of High-voltage on V pin
V
> (V + 3.6 V)
PP DD
PP
(cumulative)
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.
Rev 1.1
31
C8051T610/1/2/3/4/5/6/7
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
V
V
V
V
= 1.8 V, Clock = 25 MHz
= 1.8 V, Clock = 1 MHz
= 3.0 V, Clock = 25 MHz
= 3.0 V, Clock = 1 MHz
—
—
—
—
6.2
2.7
7
8.8
—
8.9
—
mA
mA
mA
mA
DD
DD
DD
DD
2.9
Digital Supply Current with
CPU Inactive (not accessing
EPROM)
V
V
V
V
= 1.8 V, Clock = 25 MHz
= 1.8 V, Clock = 1 MHz
= 3.0 V, Clock = 25 MHz
= 3.0 V, Clock = 1 MHz
—
—
—
—
2.2
0.41
2.3
3
mA
mA
mA
mA
DD
DD
DD
DD
—
3.1
—
0.42
Digital Supply Current
(shutdown)
Oscillator not running (stop mode),
Internal Regulator Off
—
4
—
µA
µA
V
Oscillator not running (stop or sus-
pend mode), Internal Regulator On
—
400
1.5
—
—
Digital Supply RAM Data
Retention Voltage
—
—
Specified Operating
Temperature Range
–40
0
+85
25
°C
SYSCLK (system clock
(Note 2)
—
MHz
frequency)
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. SYSCLK must be at least 32 kHz to enable debugging.
32
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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
I
I
I
I
I
I
= –3 mA, Port I/O push-pull
= –10 µA, Port I/O push-pull
= –10 mA, Port I/O push-pull
= 8.5 mA
= 10 µA
= 25 mA
V
V
- 0.2
- 0.1
—
—
—
—
—
—
—
—
—
0.4
0.1
—
—
0.6
1
V
V
V
V
V
V
V
V
µA
µA
OH
OH
OH
OL
OL
OL
DD
DD
V
- 0.4
DD
Output Low Voltage
—
—
0.6
—
—
—
Input High Voltage
Input Low Voltage
Input Leakage
Current
0.7 x V
—
DD
Weak Pullup Off
Weak Pullup On, V = 0 V
-1
—
25
50
IN
Table 7.4. Reset Electrical Characteristics
–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
—
—
—
—
0.6
50
V
DD
V
DD
RST = 0.0 V
—
25
µA
V
V
POR Ramp Time
—
—
1
ms
V
DD
DD
Monitor Threshold (V
)
1.7
1.75
625
1.8
750
RST
Missing Clock Detector
Timeout
Time from last system clock
rising edge to reset initiation
500
µs
Reset Time Delay
Delay between release of any
reset source and code
execution at location 0x0000
—
—
—
60
—
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
—
—
50
20
—
µs
DD
DD
DD
30
µA
Rev 1.1
33
C8051T610/1/2/3/4/5/6/7
Table 7.5. Internal Voltage Regulator Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Input Voltage Range
Bias Current
1.8
—
—
3.6
50
V
Normal Mode
30
µA
Table 7.6. EPROM Electrical Characteristics
Parameter
Conditions
C8051T610/1/6/7
Min
16384
8192
105
Typ
Max
—
Units
1
EPROM Size
—
—
bytes
bytes
µs
EPROM Size
C8051T612/3/4/5
—
2
3
Write Cycle Time (per Byte)
155
6.0
205
6.25
6.5
Date Code 0935 and Later
Date Code prior to 0935
5.75
V
Programming Voltage (V
)
PP
6.25
6.325
V
Notes:
1. 512 bytes at location 0x3E00 to 0x3FFF are not available for program storage.
2. The EPROM write cycle time is adjustable as part of the EPROM write sequence detailed in Section 17.1.1.
The EEPROM timing listed is for date code 1119 and later. For date codes prior to 1119, the guidance in
Section 17.1.1 will produce write times that are twice as long.
3. Refer to device errata for details.
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
IFCN = 11b
Min
24
Typ
24.5
450
Max
25
Units
MHz
µA
Oscillator Frequency
Oscillator Supply Current
25 °C, V = 3.0 V,
—
700
DD
(from V
)
OSCICN.7 = 1
DD
Power Supply Variance
Temperature Variance
Constant Temperature
Constant Supply
—
—
±0.02
±20
—
—
%/V
ppm/°C
34
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Table 7.8. 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
Power Specifications
Power Supply Current
5
—
Operating Mode, 200 ksps
—
—
600
–70
900
—
µA
dB
(V supplied to ADC0)
DD
Power Supply Rejection
Rev 1.1
35
C8051T610/1/2/3/4/5/6/7
Table 7.9. Temperature Sensor Electrical Characteristics
V
= 3.0 V, –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
Linearity
Slope
—
—
—
—
—
±0.5
3.49
±40
930
±12
—
—
—
—
—
°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 7.10. Voltage Reference Electrical Characteristics
V
= 3.0 V; –40 to +85 °C unless otherwise specified.
DD
Parameter
Conditions
Min
Typ
Max
Units
Input Voltage Range
Input Current
0
—
V
V
DD
Sample Rate = 500 ksps; VREF = 2.5 V
—
12
—
µA
36
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Table 7.11. 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
240
240
400
400
650
1100
2000
5500
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
8
6
10
14
28
1
12
—
2
20
0
5
8
6
10
14
28
12
–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
—
—
—
—
—
—
0.5
10
26
10
3
—
—
50
20
6
mV/V
µs
Supply Current at DC
Mode 0
Mode 1
Mode 2
Mode 3
µA
µA
µA
0.5
2
µA
Note: Vcm is the common-mode voltage on CP0+ and CP0–.
Rev 1.1
37
C8051T610/1/2/3/4/5/6/7
7.3. Typical Performance Curves
8.0
7.0
6.0
VDD > 1.8 V
5.0
VDD = 1.8 V
4.0
3.0
2.0
1.0
0.0
0
5
10
15
20
25
SYSCLK (MHz)
Figure 7.1. Normal Mode Digital Supply Current vs. Frequency (MPCE = 1)
2.5
2.0
VDD > 1.8 V
1.5
VDD = 1.8 V
1.0
0.5
0.0
0
5
10
15
20
25
SYSCLK (MHz)
Figure 7.2. Idle Mode Digital Supply Current vs. Frequency (MPCE = 1)
38
Rev 1.1
C8051T610/1/2/3/4/5/6/7
8. 10-Bit ADC (ADC0, C8051T610/1/2/3/6 only)
ADC0 on the C8051T610/1/2/3/6 is a 500 ksps, 10-bit successive-approximation-register (SAR) ADC with
integrated track-and-hold, a gain stage programmable to 1x or 0.5x, and a programmable window detector.
The ADC is fully configurable under software control via Special Function Registers. The ADC may be con-
figured to measure various different signals using the analog multiplexer described in Section “8.5. ADC0
Analog Multiplexer (C8051T610/1/2/3/6 only)” on page 49. The voltage reference for the ADC is selected
as described in Section “10. Voltage Reference Options” on page 54. 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 1.1
39
C8051T610/1/2/3/4/5/6/7
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). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT)
should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT
is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte over-
flows 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 “25. Timers” on page 170 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 “21. Port Input/Output” on page 113 for details on Port I/O configuration.
40
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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 42.
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
AD0TM=0
Track
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 1.1
41
C8051T610/1/2/3/4/5/6/7
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. Note that in delayed track-
ing 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 7.8 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
42
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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
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 1.1
43
C8051T610/1/2/3/4/5/6/7
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
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
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
read 000000b.
Note: In 8-bit mode AD0LJST is ignored, and ADC0L will read back 00000000b.
44
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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; 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 in
progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if
1: ADC0 conversion is in prog- AD0CM[2:0] = 000b
ress.
3
AD0WINT
ADC0 Window Compare Interrupt Flag.
0: ADC0 Window Comparison Data match has not occurred since this flag was last
cleared.
1: ADC0 Window Comparison Data match has occurred.
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 1.1
45
C8051T610/1/2/3/4/5/6/7
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
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
Bit Name
7:0 ADC0GTL[7:0]
Function
ADC0 Greater-Than Data Word Low-Order Bits.
46
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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
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
Bit Name
7:0 ADC0LTL[7:0]
Function
ADC0 Less-Than Data Word Low-Order Bits.
Rev 1.1
47
C8051T610/1/2/3/4/5/6/7
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
48
Rev 1.1
C8051T610/1/2/3/4/5/6/7
8.5. ADC0 Analog Multiplexer (C8051T610/1/2/3/6 only)
ADC0 on the C8051T610/1/2/3/6 uses an analog input multiplexer to select the positive input to the ADC.
Any of the following may be selected as the positive input: Port 1, 2 and 3 I/O pins, the on-chip temperature
sensor, or the positive power supply (V ). The ADC0 input channel is selected in the AMX0P register
DD
described in SFR Definition 8.9.
AMX0P
P1.0
Note: Not all pins exist on all
packages. See the AMX0P
selection table for details on
which pins are available for
selection.
AMUX
ADC0
P3.4
Temp
Sensor
VDD
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 to 0 the corresponding bit in register PnMDIN. To force the Crossbar to skip a Port pin, set to 1
the corresponding bit in register PnSKIP. See Section “21. Port Input/Output” on page 113 for more Port
I/O configuration details.
Rev 1.1
49
C8051T610/1/2/3/4/5/6/7
SFR Definition 8.9. AMX0P: AMUX0 Positive Channel Select
Bit
7
6
5
4
3
2
1
0
AMX0P[4:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
1
1
1
1
1
SFR Address = 0xBB
Bit
Name
Function
7:5
Unused
Unused. Read = 000b; Write = Don’t Care.
4:0 AMX0P[4:0]
AMUX0 Positive Input Selection.
Setting
00000:
00001:
00010:
00011:
00100:
00101:
00110:
00111:
01000:
01001:
01010:
01011:
01100:
01101:
01110:
01111:
10000:
10001:
10010:
10011:
10100:
10101-11101:
11110:
11111:
Channel
P1.0
Available on Packages
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
LQFP-32, QFN-28
P2.0
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
LQFP-32, QFN-28
P3.0
LQFP-32, QFN-28, QFN-24
LQFP-32
P3.1
P3.2
LQFP-32
P3.3
LQFP-32
P3.4
LQFP-32
No Input Selected
Temp Sensor
N/A
LQFP-32, QFN-28, QFN-24
LQFP-32, QFN-28, QFN-24
V
DD
50
Rev 1.1
C8051T610/1/2/3/4/5/6/7
9. Temperature Sensor (C8051T610/1/2/3/6 only)
An on-chip temperature sensor is included on the C8051T610/1/2/3/6 which can be directly accessed via
the ADC multiplexer. 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 ADC input when the ADC multiplexer is set correctly.
TEMP
The TEMPE bit in register REF0CN enables/disables the temperature sensor, as described in SFR Defini-
tion 10.1. While disabled, the temperature sensor defaults to a high impedance state and any ADC mea-
surements performed on the sensor will result in meaningless data. Refer to Table 7.9 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 7.9 on page 36 for specifications). For absolute temperature measurements, offset
and/or gain calibration is recommended. A single-point offset measurement of the temperature sensor is
performed on each device during production test. The registers TOFFH and TOFFL, shown in SFR Defini-
tion 9.1 and SFR Definition 9.2 represent the output of the ADC when reading the temperature sensor at 0
degrees Celsius, and using the internal regulator as a voltage reference.
Figure 9.2 shows the typical temperature sensor error assuming a 1-point calibration at 0 °C. Parameters
that affect ADC measurement, in particular the voltage reference value, will also affect temperature
measurement.
Rev 1.1
51
C8051T610/1/2/3/4/5/6/7
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
52
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 9.1. TOFFH: Temperature Offset Measurement High Byte
Bit
7
6
5
4
3
2
1
0
TOFF[9:2]
R/W
Name
Type
Reset
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0x86
Bit Name
7:0 TOFF[9:2]
Function
Temperature Sensor Offset High Order Bits.
The temperature sensor offset registers represent the output of the ADC when mea-
suring the temperature sensor at 0 °C, with the voltage reference set to the internal
regulator. The temperature sensor offset information is left-justified. One LSB of this
measurement is equivalent to one LSB of the ADC output under the measurement
conditions.
SFR Definition 9.2. TOFFL: Temperature Offset Measurement Low Byte
Bit
7
6
5
4
3
2
1
0
TOFF[1:0]
R/W
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
Varies
Varies
SFR Address = 0x85
Bit Name
7:6 TOFF[1:0]
Function
Temperature Sensor Offset Low Order Bits.
The temperature sensor offset registers represent the output of the ADC when mea-
suring the temperature sensor at 0 °C, with the voltage reference set to the internal
regulator. The temperature sensor offset information is left-justified. One LSB of this
measurement is equivalent to one LSB of the ADC output under the measurement
conditions.
5:0
Unused
Unused. Read = 000000b; Write = Don’t Care.
Rev 1.1
53
C8051T610/1/2/3/4/5/6/7
10. Voltage Reference Options
The Voltage reference multiplexer for the ADC is configurable to use an externally connected voltage refer-
ence, the unregulated power supply voltage (V ), or the regulated 1.8 V internal supply (see Figure 10.1).
DD
The REFSL bit in the Reference Control register (REF0CN, SFR Definition 10.1) selects the reference
source for the ADC. For an external source, REFSL should be set to 0 to select the VREF pin. To use V
DD
as the reference source, REFSL should be set to 1. To override this selection and use the internal regulator
as the reference source, the REGOVR bit can be set to 1. The electrical specifications for the voltage ref-
erence circuit are given in Section “7. Electrical Characteristics” on page 31.
Important Note about the VREF Pin: When using an external voltage reference, the VREF pin should be
configured as an analog pin and skipped by the Digital Crossbar. Refer to Section “21. Port Input/Output”
on page 113 for the location of the VREF pin, as well as details of how to configure the pin in analog mode
and to be skipped by the crossbar.
REF0CN
EN
VDD
Temp Sensor
To Analog Mux
External
Voltage
Reference
Circuit
R1
VREF
0
1
0
GND
VREF
(to ADC)
VDD
Internal
Regulator
1
+
4.7F
0.1F
REGOVR
Recommended Bypass
Capacitors
Figure 10.1. Voltage Reference Functional Block Diagram
54
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 10.1. REF0CN: Reference Control
Bit
7
6
5
4
3
2
1
0
REGOVR
REFSL
TEMPE
Name
Type
Reset
R
0
R
0
R
0
R/W
0
R/W
0
R/W
0
R
0
R
0
SFR Address = 0xD1
Bit
7:5
4
Name
Function
Unused Unused. Read = 000b; Write = Don’t Care.
REGOVR Regulator Reference Override.
This bit “overrides” the REFSL bit, and allows the internal regulator to be used as a ref-
erence source.
0: The voltage reference source is selected by the REFSL bit.
1: The internal regulator is used as the voltage reference.
3
REFSL Voltage Reference Select.
This bit selects the ADCs voltage reference.
0: V pin used as voltage reference.
REF
1: V used as voltage reference.
DD
2
TEMPE Temperature Sensor Enable Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
1:0
Unused Unused. Read = 00b; Write = Don’t Care.
Rev 1.1
55
C8051T610/1/2/3/4/5/6/7
11. Voltage Regulator (REG0)
C8051T610/1/2/3/4/5/6/7 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
DD
help 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 34
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.
56
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 11.1. REG0CN: Voltage Regulator Control
Bit
7
6
5
4
3
2
1
0
STOPCF BYPASS
MPCE
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 = 0xC7
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, turning off the regulator, and allowing the
core to run directly from the V supply pin.
DD
0: Normal Mode—Regulator is on.
1: Bypass Mode—Regulator is off, 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 31. Doing so
may cause permanent damage to the device.
5:1 Reserved Reserved. Must Write 00000b.
0
MPCE
Memory Power Controller Enable.
This bit can help the system save power at slower system clock frequencies (about
2.0 MHz or less) by automatically shutting down the EPROM memory between clocks
when information is not being fetched from the EPROM memory.
0: Normal Mode—Memory power controller disabled (EPROM memory is always on).
1: Low Power Mode—Memory power controller enabled (EPROM memory turns on/off
as needed).
Note: If an external clock source is used with the Memory Power Controller enabled, and the
clock frequency changes from slow (<2.0 MHz) to fast (> 2.0 MHz), the EPROM power
will turn on, and up to 20 clocks may be "skipped" to ensure that the EPROM power is
stable before reading memory.
Rev 1.1
57
C8051T610/1/2/3/4/5/6/7
12. Comparator0 and Comparator1
C8051T610/1/2/3/4/5/6/7 devices include two on-chip programmable voltage comparators: Comparator0 is
shown in Figure 12.1, Comparator1 is shown in Figure 12.2. The two comparators operate identically with
the following exceptions: (1) Their input selections differ as described in Section “12.1. Comparator Multi-
plexers” on page 65; (2) Comparator0 can be used as a reset source.
The Comparators offer 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 CP1), or an
asynchronous “raw” output (CP0A or CP1A). The asynchronous signals are available even when the sys-
tem clock is not active. This allows the Comparators to operate and generate an output with the device in
STOP mode. When assigned to a Port pin, the Comparator outputs may be configured as open drain or
push-pull (see Section “21.4. Port I/O Initialization” on page 121). Comparator0 may also be used as a
reset source (see Section “19.5. Comparator0 Reset” on page 104).
The Comparator inputs are selected by the comparator input multiplexers, as detailed in Section
“12.1. Comparator Multiplexers” on page 65.
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
58
Rev 1.1
C8051T610/1/2/3/4/5/6/7
CPT1CN
VDD
CP1 +
CP1 -
+
-
CP1
Comparator
Input Mux
SET
CLR
SET
D
Q
Q
D
Q
Q
CLR
Crossbar
(SYNCHRONIZER)
CP1A
GND
CPT1MD
0
1
CP1
Interrupt
CP1EN
EA
CP1RIF
CP1FIF
0
0
1
1
0
1
Figure 12.2. Comparator1 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 “21.3. Priority Crossbar Decoder” on
page 117 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be
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 31.
The Comparator response time may be configured in software via the CPTnMD registers (see SFR Defini-
tion 12.2 and SFR Definition 12.4). Selecting a longer response time reduces the Comparator supply cur-
rent.
Rev 1.1
59
C8051T610/1/2/3/4/5/6/7
CPn+
VIN+
VIN-
+
CPn
_
OUT
CPn-
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CPnHYP Bits)
VIN-
Negative Hysteresis Voltage
INPUTS
(Programmed by CPnHYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Maximum
Negative Hysteresis
Positive Hysteresis
Disabled
Maximum
Positive Hysteresis
Figure 12.3. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN
(for n = 0 or 1). The user can program both the amount of hysteresis voltage (referred to the input voltage)
and the positive and negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3–0 in the Comparator Control Register CPTnCN
(shown in SFR Definition 12.1). The amount of negative hysteresis voltage is determined by the settings of
the CPnHYN bits. Settings of 20, 10 or 5 mV of nominal negative hysteresis can be programmed, or nega-
tive hysteresis can be disabled. In a similar way, the amount of positive hysteresis is determined by the
setting the CPnHYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Inter-
rupt enable and priority control, see Section “16.1. MCU Interrupt Sources and Vectors” on page 86). The
CPnFIF flag is set to logic 1 upon a Comparator falling-edge occurrence, and the CPnRIF 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 CPnRIE to a logic 1. The Compar-
ator falling-edge interrupt mask is enabled by setting CPnFIE to a logic 1.
The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Compar-
ator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0.
Note that false rising edges and falling edges can be detected when the comparator is first powered on or
if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the
rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is
enabled or its mode bits have been changed.
60
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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
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 1.1
61
C8051T610/1/2/3/4/5/6/7
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
Bit
7:6
5
Name
Unused
CP0RIE
Function
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)
62
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SFR Definition 12.3. CPT1CN: Comparator1 Control
Bit
7
6
5
4
3
2
1
0
CP1EN
CP1OUT
CP1RIF
CP1FIF
CP1HYP[1:0]
R/W
CP1HYN[1:0]
R/W
Name
Type
Reset
R/W
0
R
0
R/W
0
R/W
0
0
0
0
0
SFR Address = 0x9A
Bit
Name
Function
7
CP1EN
Comparator1 Enable Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
6
5
4
CP1OUT
CP1RIF
CP1FIF
Comparator1 Output State Flag.
0: Voltage on CP1+ < CP0–.
1: Voltage on CP1+ > CP0–.
Comparator1 Rising-Edge Flag. Must be cleared by software.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
Comparator1 Falling-Edge Flag. Must be cleared by software.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge has occurred.
3:2 CP1HYP[1:0] Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
1:0 CP1HYN[1:0] Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev 1.1
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SFR Definition 12.4. CPT1MD: Comparator1 Mode Selection
Bit
7
6
5
4
3
2
1
0
CP1RIE
CP1FIE
CP1MD[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 = 0x9C
Bit
7:6
5
Name
Unused
CP1RIE
Function
Unused. Read = 00b, Write = Don’t Care.
Comparator1 Rising-Edge Interrupt Enable.
0: Comparator1 Rising-edge interrupt disabled.
1: Comparator1 Rising-edge interrupt enabled.
4
CP1FIE
Unused
Comparator1 Falling-Edge Interrupt Enable.
0: Comparator1 Falling-edge interrupt disabled.
1: Comparator1 Falling-edge interrupt enabled.
3:2
Unused. Read = 00b, Write = don’t care.
1:0 CP1MD[1:0] Comparator1 Mode Select.
These bits affect the response time and power consumption for Comparator1.
00: Mode 0 (Fastest Response Time, Highest Power Consumption)
01: Mode 1
10: Mode 2
11: Mode 3 (Slowest Response Time, Lowest Power Consumption)
64
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12.1. Comparator Multiplexers
C8051T610/1/2/3/4/5/6/7 devices include analog input multiplexers to connect Port I/O pins to the compar-
ator inputs. The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 12.5). The
CMX0P1–CMX0P0 bits select the Comparator0 positive input; the CMX0N1–CMX0N0 bits select the
Comparator0 negative input. Likewise, the Comparator1 inputs are selected in the CPT1MX register (SFR
Definition 12.6). 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 “21.5. Special Function Registers
for Accessing and Configuring Port I/O” on page 124).
P1.0
P1.4
P2.0
P2.4
P1.2
P1.6
P2.2
P2.6
VDD
VDD
+
-
+
-
CP0 +
CP0 -
CP1 +
CP1 -
P1.1
P1.5
P2.1
P2.5
P1.3
P1.7
P2.3
P2.7
GND
GND
CPT0MX
CPT1MX
Figure 12.4. Comparator Input Multiplexer Block Diagram
Rev 1.1
65
C8051T610/1/2/3/4/5/6/7
SFR Definition 12.5. CPT0MX: Comparator0 MUX Selection
Bit
7
6
5
4
3
2
1
0
CMX0N[1:0]
R/W
CMX0P[1:0]
R/W
Name
Type
Reset
R
0
R
0
R
0
R
0
0
0
0
0
SFR Address = 0x9F
Bit
Name
Function
7:6
Unused
Unused, Read = 00b; Write = Don’t Care
5:4 CMX0N[1:0]
Comparator0 Negative Input MUX Selection.
00:
01:
10:
11:
P1.1
P1.5
P2.1
P2.5
3:2
Unused
Unused, Read = 00b; Write = Don’t Care
1:0 CMX0P[1:0]
Comparator0 Positive Input MUX Selection.
00:
01:
10:
11:
P1.0
P1.4
P2.0
P2.4
66
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SFR Definition 12.6. CPT1MX: Comparator1 MUX Selection
Bit
7
6
5
4
3
2
1
0
CMX1N[1:0]
R/W
CMX1P[1:0]
R/W
Name
Type
Reset
R
0
R
0
R
0
R
0
0
0
0
0
SFR Address = 0x9E
Bit
Name
Function
7:6
Unused
Unused. Read = 00b, Write = Don’t Care
5:4 CMX0N[1:0] Comparator1 Negative Input MUX Selection.
00:
01:
10:
11:
P1.3
P1.7
P2.3
P2.7
3:2
Unused
Unused. Read = 00b, Write = Don’t Care
1:0 CMX0P[1:0] Comparator1 Positive Input MUX Selection.
00:
01:
10:
11:
P1.2
P1.6
P2.1
P2.6
Rev 1.1
67
C8051T610/1/2/3/4/5/6/7
13. 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 27), 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 13.1 for a block diagram).
The CIP-51 includes the following features:
l Fully Compatible with MCS-51 Instruction Set
l 25 MIPS Peak Throughput with 25 MHz Clock
l 0 to 25 MHz Clock Frequency
l Reset Input
l Power Management Modes
l On-chip Debug Logic
l Extended Interrupt Handler
l 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
D8
BUFFER
SFR
BUS
INTERFACE
D8
SFR_WRITE_DATA
SFR_READ_DATA
DATA POINTER
D8
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 13.1. CIP-51 Block Diagram
68
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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
13.1. 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.
13.1.1. 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 13.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
Rev 1.1
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C8051T610/1/2/3/4/5/6/7
Table 13.1. 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
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
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
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
70
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Table 13.1. 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 1.1
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Table 13.1. 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
2
2
2
2
2
3
3
3
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
4/5
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
72
Rev 1.1
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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 1.1
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13.2. 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 13.1. 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
Bit
Name
DPL[7:0] Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR.
Function
7:0
SFR Definition 13.2. 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
Bit
Name
Function
7:0
DPH[7:0] Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR.
74
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SFR Definition 13.3. 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
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 13.4. 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; Bit-Addressable
Bit
Name
Function
7:0
ACC[7:0] Accumulator.
This register is the accumulator for arithmetic operations.
SFR Definition 13.5. 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; Bit-Addressable
Bit
Name
Function
7:0
B[7:0]
B Register.
This register serves as a second accumulator for certain arithmetic operations.
Rev 1.1
75
C8051T610/1/2/3/4/5/6/7
SFR Definition 13.6. 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; 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:
l An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
l A MUL instruction results in an overflow (result is greater than 255).
l 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.
76
Rev 1.1
C8051T610/1/2/3/4/5/6/7
14. 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
C8051T610/1/2/3/4/5/6/7 device family is shown in Figure 14.1
C8051T610/1/6/7
CODE MEMORY
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
0xFF
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Register's
(Direct Addressing Only)
RESERVED
0x3E00
0x3DFF
0x80
0x7F
(Direct and Indirect
Addressing)
Lower 128 RAM
(Direct and Indirect
Addressing)
16k Bytes EPROM
0x30
0x2F
Bit Addressable
0x20
0x1F
General Purpose
Registers
0x0000
0x00
C8051T612/3/4/5
CODE MEMORY
EXTERNAL DATA ADDRESS SPACE
0xFFFF
RESERVED
Same 1024 bytes as from
0x0000 to 0x03FF, wrapped
on 1024-byte boundaries
0x2000
0x1FFF
0x0400
0x03FF
8k Bytes EPROM
XRAM - 1024 Bytes
(accessable using MOVX
instruction)
0x0000
0x0000
Figure 14.1. Memory Map
Rev 1.1
77
C8051T610/1/2/3/4/5/6/7
14.1. Program Memory
The CIP-51 core has a 64 kB program memory space. The C8051T610/1/6/7 implements 15872 bytes of
this program memory space as in-system, Byte-Programmable EPROM, organized in a contiguous block
from addresses 0x0000 to 0x3FFF. Note that 512 bytes (0x3E00 – 0x3FFF) of this memory are reserved
for factory use and are not available for user program storage. The C8051T612/3/4/5 implements 8192
bytes of EPROM program memory space. Figure 14.2 shows the program memory maps for
C8051T610/1/2/3/4/5/6/7 devices.
C8051T610/1/6/7
C8051T612/3/4/5
0x3FFF
0x3FFF
0x3FFE
Security Byte
Security Byte
0x3FFE
0x3E00
0x3DFF
Reserved
Reserved
0x2000
0x1FFF
15872 Bytes
EPROM Memory
8192 Bytes
EPROM Memory
0x0000
0x0000
Figure 14.2. Program Memory Map
Program memory is read-only from within firmware. Individual program memory bytes can be read using
the MOVC instruction. This facilitates the use of EPROM space for constant storage.
14.2. Data Memory
The C8051T610/1/2/3/4/5/6/7 device family includes 1280 bytes of RAM data memory. 256 bytes of this
memory is mapped into the internal RAM space of the 8051. 1024 bytes of this memory is on-chip “exter-
nal” memory. The data memory map is shown in Figure 14.1 for reference.
14.2.1. 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
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 14.1 illustrates the data memory organization of the
C8051T610/1/2/3/4/5/6/7.
78
Rev 1.1
C8051T610/1/2/3/4/5/6/7
14.2.1.1. 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 13.6). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes
use registers R0 and R1 as index registers.
14.2.1.2. 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.
14.2.1.3. 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.
14.2.2. External RAM
There are 1024 bytes of on-chip RAM mapped into the external data memory space. All of these address
locations may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or
using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit address operand
(such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Con-
trol Register (EMI0CN as shown in SFR Definition 14.1).
For a 16-bit MOVX operation (@DPTR), the upper 7 bits of the 16-bit external data memory address word
are "don't cares". As a result, the 1024-byte RAM is mapped modulo style over the entire 64 k external
data memory address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses
0x0400, 0x0800, 0x0C00, 0x1000, etc. This is a useful feature when performing a linear memory fill, as the
address pointer doesn't have to be reset when reaching the RAM block boundary.
Rev 1.1
79
C8051T610/1/2/3/4/5/6/7
SFR Definition 14.1. EMI0CN: External Memory Interface Control
Bit
7
6
5
4
3
2
1
0
PGSEL
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 = 0xAA
Bit
Name
Function
7:2
Unused
Unused. Read = 000000b; Write = Don’t Care
1:0 PGSEL[1:0]
XRAM Page Select.
The EMI0CN register provides the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page
of RAM. Since the upper (unused) bits of the register are always zero, the PGSEL
bits determine which page of XRAM is accessed.
For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be
accessed.
80
Rev 1.1
C8051T610/1/2/3/4/5/6/7
15. 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 C8051T610/1/2/3/4/5/6/7's resources and
peripherals. 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
C8051T610/1/2/3/4/5/6/7. This allows the addition of new functionality while retaining compatibility with the
MCS-51™ instruction set. Table 15.1 lists the SFRs implemented in the C8051T610/1/2/3/4/5/6/7 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 15.2, for a detailed description of each register.
Table 15.1. Special Function Register (SFR) Memory Map
F8 SPI0CN
F0
PCA0L
PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 PCA0CPH4 VDM0CN
P1MDIN P2MDIN P3MDIN EIP1
B
P0MDIN
E8 ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 RSTSRC
E0 ACC XBR0 XBR1 IT01CF EIE1
D8 PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4
D0
PSW
REF0CN
P0SKIP
TMR2L
P1SKIP
TMR2H
P2SKIP
C8 TMR2CN
TMR2RLL TMR2RLH
C0 SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH
REG0CN
B8
B0
A8
A0
IP
P3
IE
AMX0P
OSCICL
ADC0CF
ADC0L
ADC0H
OSCXCN OSCICN
CLKSEL EMI0CN
SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT P3MDOUT
P2
98 SCON0
SBUF0
CPT1CN
CPT0CN
CPT1MD
TMR3L
TH0
CPT0MD
TMR3H
TH1
CPT1MX
CPT0MX
90
88
80
P1
TCON
P0
TMR3CN TMR3RLL TMR3RLH
TMOD
SP
TL0
DPL
2(A)
TL1
DPH
3(B)
CKCON
TOFFH
6(E)
TOFFL
5(D)
PCON
7(F)
0(8)
1(9)
4(C)
(bit addressable)
Rev 1.1
81
C8051T610/1/2/3/4/5/6/7
Table 15.2. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
ACC
Address
Description
Page
0xE0
Accumulator
75
0xBC
0xE8
0xC4
0xC3
0xBE
0xBD
0xC6
0xC5
0xBB
0xF0
0x8E
0xA9
0x9B
0x9D
0x9F
0x9A
0x9C
0x9E
0x83
0x82
0xE6
0xF6
0xAA
0xA8
0xB8
0xE4
0xB3
0xB2
0xB1
0x80
0xF1
0xA4
ADC0 Configuration
ADC0 Control
43
45
ADC0CF
ADC0CN
ADC0GTH
ADC0GTL
ADC0H
ADC0L
ADC0LTH
ADC0LTL
AMX0P
B
ADC0 Greater-Than Compare High
ADC0 Greater-Than Compare Low
ADC0 High
46
46
44
ADC0 Low
44
ADC0 Less-Than Compare Word High
ADC0 Less-Than Compare Word Low
AMUX0 Positive Channel Select
B Register
47
47
50
75
Clock Control
171
107
61
CKCON
CLKSEL
CPT0CN
CPT0MD
CPT0MX
CPT1CN
CPT1MD
CPT1MX
DPH
Clock Select
Comparator0 Control
Comparator0 Mode Selection
Comparator0 MUX Selection
Comparator1 Control
62
66
63
Comparator1 Mode Selection
Comparator1 MUX Selection
Data Pointer High
64
67
74
Data Pointer Low
74
DPL
Extended Interrupt Enable 1
Extended Interrupt Priority 1
External Memory Interface Control
Interrupt Enable
90
EIE1
91
EIP1
80
EMI0CN
IE
88
Interrupt Priority
89
IP
INT0/INT1 Configuration
Internal Oscillator Calibration
Internal Oscillator Control
External Oscillator Control
Port 0 Latch
93
IT01CF
OSCICL
OSCICN
OSCXCN
P0
108
109
111
124
125
125
Port 0 Input Mode Configuration
Port 0 Output Mode Configuration
P0MDIN
P0MDOUT
82
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Table 15.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
P0SKIP
Address
Description
Page
0xD4
Port 0 Skip
Port 1 Latch
126
0x90
0xF2
0xA5
0xD5
0xA0
0xF3
0xA6
0xD6
0xB0
0xF4
0xA7
0xD8
0xFC
0xEA
0xEC
0xEE
0xFE
0xFB
0xE9
0xEB
0xED
0xFD
0xDA
0xDB
0xDC
0xDD
0xDE
0xFA
0xF9
0xD9
0x87
0xD0
0xD1
126
127
127
128
128
129
129
130
130
131
131
203
207
207
207
207
207
207
207
207
207
207
205
205
205
205
205
206
206
204
99
P1
Port 1 Input Mode Configuration
Port 1 Output Mode Configuration
Port 1 Skip
P1MDIN
P1MDOUT
P1SKIP
Port 2 Latch
P2
Port 2 Input Mode Configuration
Port 2 Output Mode Configuration
Port 2 Skip
P2MDIN
P2MDOUT
P2SKIP
Port 3 Latch
P3
Port 3 Input Mode Configuration
Port 3 Output Mode Configuration
PCA Control
P3MDIN
P3MDOUT
PCA0CN
PCA0CPH0
PCA0CPH1
PCA0CPH2
PCA0CPH3
PCA0CPH4
PCA0CPL0
PCA0CPL1
PCA0CPL2
PCA0CPL3
PCA0CPL4
PCA0CPM0
PCA0CPM1
PCA0CPM2
PCA0CPM3
PCA0CPM4
PCA0H
PCA Capture 0 High
PCA Capture 1 High
PCA Capture 2 High
PCA Capture 3 High
PCA Capture 4 High
PCA Capture 0 Low
PCA Capture 1 Low
PCA Capture 2 Low
PCA Capture 3 Low
PCA Capture 4 Low
PCA Module 0 Mode Register
PCA Module 1 Mode Register
PCA Module 2 Mode Register
PCA Module 3 Mode Register
PCA Module 4 Mode Register
PCA Counter High
PCA Counter Low
PCA0L
PCA Mode
PCA0MD
PCON
Power Control
Program Status Word
Voltage Reference Control
76
PSW
55
REF0CN
Rev 1.1
83
C8051T610/1/2/3/4/5/6/7
Table 15.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
REG0CN
RSTSRC
SBUF0
SCON0
SMB0CF
SMB0CN
SMB0DAT
SP
Address
Description
Voltage Regulator Control
Page
0xC7
57
0xEF
0x99
0x98
0xC1
0xC0
0xC2
0x81
0xA1
0xA2
0xF8
0xA3
0x88
0x8C
0x8D
0x8A
0x8B
0x89
0xC8
0xCD
0xCC
0xCB
0xCA
0x91
0x95
0x94
0x93
0x92
0x86
0x85
0xFF
0xE1
0xE2
Reset Source Configuration/Status
UART0 Data Buffer
105
155
154
138
140
142
75
UART0 Control
SMBus Configuration
SMBus Control
SMBus Data
Stack Pointer
SPI Configuration
164
166
165
166
176
179
179
178
178
177
182
184
183
183
183
187
189
188
188
188
53
SPI0CFG
SPI0CKR
SPI0CN
SPI0DAT
TCON
SPI Clock Rate Control
SPI Control
SPI Data
Timer/Counter Control
Timer/Counter 0 High
Timer/Counter 1 High
Timer/Counter 0 Low
Timer/Counter 1 Low
Timer/Counter Mode
TH0
TH1
TL0
TL1
TMOD
Timer/Counter 2 Control
Timer/Counter 2 High
Timer/Counter 2 Low
Timer/Counter 2 Reload High
Timer/Counter 2 Reload Low
Timer/Counter 3Control
Timer/Counter 3 High
Timer/Counter 3Low
TMR2CN
TMR2H
TMR2L
TMR2RLH
TMR2RLL
TMR3CN
TMR3H
TMR3L
TMR3RLH
TMR3RLL
TOFFH
TOFFL
Timer/Counter 3 Reload High
Timer/Counter 3 Reload Low
Temperature Sensor Offset Measurement High
Temperature Sensor Offset Measurement Low
53
V
Monitor Control
103
122
123
VDM0CN
XBR0
DD
Port I/O Crossbar Control 0
Port I/O Crossbar Control 1
XBR1
84
Rev 1.1
C8051T610/1/2/3/4/5/6/7
16. Interrupts
The C8051T610/1/2/3/4/5/6/7 includes an extended interrupt system supporting a total of 14 interrupt
sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and exter-
nal 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.
Note: Any instruction that clears a bit to disable an interrupt should be immediately followed by an instruc-
tion that has two or more opcode bytes. Using EA (global interrupt enable) as an example:
// in 'C':
EA = 0; // clear EA bit.
EA = 0; // this is a dummy instruction with two-byte opcode.
; in assembly:
CLR EA ; clear EA bit.
CLR EA ; this is a dummy instruction with two-byte opcode.
For example, if an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction
which clears a bit to disable an interrupt source), and the instruction is followed by a single-cycle instruc-
tion, the interrupt may be taken. However, a read of the enable bit will return a '0' inside the interrupt ser-
vice routine. When the bit-clearing opcode is followed by a multi-cycle instruction, the interrupt will not be
taken.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
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 1.1
85
C8051T610/1/2/3/4/5/6/7
16.1. MCU Interrupt Sources and Vectors
The C8051T610/1/2/3/4/5/6/7 MCUs support 14 interrupt sources. Software can simulate an interrupt by
setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be
generated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU
interrupt sources, associated vector addresses, priority order and control bits are summarized in
Table 16.1. 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).
16.1.1. 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 16.1.
16.1.2. 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.
86
Rev 1.1
C8051T610/1/2/3/4/5/6/7
Table 16.1. 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
N
ET2 (IE.5) PT2 (IP.5)
ESPI0
(IE.6)
PSPI0
(IP.6)
SMB0
0x003B
7
Y
N
ESMB0
(EIE1.0)
PSMB0
(EIP1.0)
N/A
RESERVED
ADC0 Window Com-
pare
ADC0 Conversion
Complete
0x0043
0x004B
8
9
N/A
AD0WINT
(ADC0CN.3)
AD0INT (ADC0CN.5)
N/A N/A N/A
Y
Y
Y
N
N
N
EWADC0 PWADC0
(EIE1.2)
EADC0
(EIE1.3)
EPCA0
(EIE1.4)
(EIP1.2)
PADC0
(EIP1.3)
PPCA0
(EIP1.4)
0x0053
10
11
Programmable Coun- 0x005B
ter Array
CF (PCA0CN.7)
CCFn (PCA0CN.n)
COVF (PCA0PWM.6)
CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5)
CP1FIF (CPT1CN.4)
CP1RIF (CPT1CN.5)
TF3H (TMR3CN.7)
TF3L (TMR3CN.6)
Comparator0
0x0063
0x006B
0x0073
12
13
14
N
N
N
N
N
N
ECP0
PCP0
(EIE1.5)
(EIP1.5)
Comparator1
ECP1
PCP1
(EIE1.6)
ET3
(EIP1.6)
PT3
Timer 3 Overflow
(EIE1.7)
(EIP1.7)
16.2. 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 1.1
87
C8051T610/1/2/3/4/5/6/7
SFR Definition 16.1. 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; 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.
88
Rev 1.1
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SFR Definition 16.2. 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; Bit-Addressable
Bit
Name
Function
7
Unused Unused. Read = 1, 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 1.1
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C8051T610/1/2/3/4/5/6/7
SFR Definition 16.3. EIE1: Extended Interrupt Enable 1
Bit
7
6
5
4
3
2
1
0
ET3
ECP1
ECP0
EPCA0
EADC0
EWADC0 Reserved
ESMB0
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 = 0xE6
Bit
Name
Function
7
ET3
Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt requests generated by the TF3L or TF3H flags.
6
5
4
3
2
ECP1
ECP0
Enable Comparator1 (CP1) Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 interrupts.
1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags.
Enable Comparator0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags.
EPCA0 Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
EADC0 Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
EWADC0 Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT).
1
0
Reserved Reserved. Must Write 0.
ESMB0 Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
90
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SFR Definition 16.4. EIP1: Extended Interrupt Priority 1
Bit
7
6
5
4
3
2
1
0
PT3
PCP1
PCP0
PPCA0
PADC0
PWADC0 Reserved
PSMB0
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 = 0xF6
Bit
Name
Function
7
PT3
Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
6
5
4
3
2
PCP1
PCP0
Comparator1 (CP1) Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 interrupt set to low priority level.
1: CP1 interrupt set to high priority level.
Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
PPCA0 Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority level.
1: PCA0 interrupt set to high priority level.
PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
PWADC0 ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority level.
1: ADC0 Window interrupt set to high priority level.
1
0
Reserved Reserved. Must Write 0.
PSMB0 SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
Rev 1.1
91
C8051T610/1/2/3/4/5/6/7
16.3. External Interrupts INT0 and INT1
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 “25.1. Timer 0 and Timer 1” on page 172) 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 16.5). 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 “21.3. Priority Crossbar
Decoder” on page 117 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.
92
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SFR Definition 16.5. 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
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
Rev 1.1
93
C8051T610/1/2/3/4/5/6/7
17. EPROM Memory
Electrically programmable read-only memory (EPROM) is included on-chip for program code storage. The
EPROM memory can be programmed via the C2 debug and programming interface when a special pro-
gramming voltage is applied to the V pin. Each location in EPROM memory is programmable only once
PP
(i.e., non-erasable). Table 7.6 on page 34 shows the EPROM specifications.
17.1. Programming and Reading the EPROM Memory
Reading and writing the EPROM memory is accomplished through the C2 programming and debug inter-
face. When creating hardware to program the EPROM, it is necessary to follow the programming steps
listed below. Refer to the “C2 Interface Specification” available at http://www.silabs.com for details on com-
municating via the C2 interface. Section “27. C2 Interface” on page 208 has information about C2 register
addresses for the C8051T610/1/2/3/4/5/6/7.
17.1.1. EPROM Write Procedure
1. Reset the device using the RST pin.
2. Wait at least 20 µs before sending the first C2 command.
3. Place the device in core reset: Write 0x04 to the DEVCTL register.
4. Set the device to program mode (1st step): Write 0x40 to the EPCTL register.
5. Set the device to program mode (2nd step): Write 0x4A to the EPCTL register.
Note: Prior to date code 1119, 0x58 should be written to EPCTL.
6. Apply the VPP programming Voltage.
7. Write the first EPROM address for programming to EPADDRH and EPADDRL.
8. Write a data byte to EPDAT. EPADDRH:L will increment by 1 after this write.
9. Use a C2 Address Read command to poll for write completion.
10.(Optional) Check the ERROR bit in register EPSTAT and abort the programming operation if necessary.
11.If programming is not finished, return to Step 8 to write the next address in sequence, or return to
Step 7 to program a new address.
12.Remove the VPP programming Voltage.
13.Remove program mode (1st step): Write 0x40 to the EPCTL register.
14.Remove program mode (2nd step): Write 0x00 to the EPCTL register.
15.Reset the device: Write 0x02 and then 0x00 to the DEVCTL register.
Important Note: There is a finite amount of time which V can be applied without damaging the device,
PP
which is cumulative over the life of the device. Refer to Table 7.1 on page 31 for the V timing specifica-
PP
tion.
94
Rev 1.1
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17.1.2. EPROM Read Procedure
1. Reset the device using the /RST pin.
2. Wait at least 20 µs before sending the first C2 command.
3. Place the device in core reset: Write 0x04 to the DEVCTL register.
4. Write 0x00 to the EPCTL register.
5. Write the first EPROM address for reading to EPADDRH and EPADDRL.
6. Read a data byte from EPDAT. EPADDRH:L will increment by 1 after this read.
7. (Optional) Check the ERROR bit in register EPSTAT and abort the memory read operation if necessary.
8. If reading is not finished, return to Step 6 to read the next address in sequence, or return to Step 5 to
select a new address.
9. Remove read mode (1st step): Write 0x40 to the EPCTL register.
10.Remove read mode (2nd step): Write 0x00 to the EPCTL register.
11.Reset the device: Write 0x02 and then 0x00 to the DEVCTL register.
17.2. Security Options
The C8051T610/1/2/3/4/5/6/7 devices provide security options to prevent unauthorized viewing of proprie-
tary program code and constants. A security byte in EPROM address space can be used to lock the pro-
gram memory from being read or written across the C2 interface. When read, the RDLOCK and WRLOCK
bits in register EPSTAT will indicate the lock status of the location currently addressed by EPADDR.
Table 17.1 shows the security byte decoding. See Section “14. Memory Organization” on page 77 for the
security byte location and EPROM memory map.
Important Note: Once the security byte has been written, there are no means of unlocking the
device. Locking memory from write access should be performed only after all other code has been
successfully programmed to memory.
Table 17.1. Security Byte Decoding
Bits
Description
7–4
Write Lock: Clearing any of these bits to logic 0 prevents all code
memory from being written across the C2 interface.
3–0
Read Lock: Clearing any of these bits to logic 0 prevents all code
memory from being read across the C2 interface.
Rev 1.1
95
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17.3. Program Memory CRC
A CRC engine is included on-chip which provides a means of verifying EPROM contents once the device
has been programmed. The CRC engine is available for EPROM verification even if the device is fully read
and write locked, allowing for verification of code contents at any time.
The CRC engine is operated through the C2 debug and programming interface, and performs 16-bit CRCs
on individual 256-Byte blocks of program memory, or a 32-bit CRC the entire memory space. To prevent
hacking and extrapolation of security-locked source code, the CRC engine will only allow CRCs to be per-
formed on contiguous 256-Byte blocks beginning on 256-Byte boundaries (lowest 8-bits of address are
0x00). For example, the CRC engine can perform a CRC for locations 0x0400 through 0x04FF, but it can-
not perform a CRC for locations 0x0401 through 0x0500, or on block sizes smaller or larger than
256 bytes.
17.3.1. Performing 32-bit CRCs on Full EPROM Content
A 32-bit CRC on the entire EPROM space is initiated by writing to the CRC1 byte over the C2 interface.
The CRC calculation begins at address 0x0000 and ends at the end of user EPROM space. The EPBusy
bit in register C2ADD will be set during the CRC operation, and cleared once the operation is complete.
The 32-bit results will be available in the CRC3-0 registers. CRC3 is the MSB, and CRC0 is the LSB. The
polynomial used for the 32-bit CRC calculation is 0x04C11DB7.
Note: If a 16-bit CRC has been performed since the last device reset, a device reset should be initiated
before performing a 32-bit CRC operation.
17.3.2. Performing 16-bit CRCs on 256-Byte EPROM Blocks
A 16-bit CRC of individual 256-byte blocks of EPROM can be initiated by writing to the CRC0 byte over the
C2 interface. The value written to CRC0 is the high byte of the beginning address for the CRC. For exam-
ple, if CRC0 is written to 0x02, the CRC will be performed on the 256-bytes beginning at address 0x0200,
and ending at address 0x2FF. The EPBusy bit in register C2ADD will be set during the CRC operation, and
cleared once the operation is complete. The 16-bit results will be available in the CRC1-0 registers. CRC1
is the MSB, and CRC0 is the LSB. The polynomial for the 16-bit CRC calculation is 0x1021
96
Rev 1.1
C8051T610/1/2/3/4/5/6/7
18. Power Management Modes
The C8051T610/1/2/3/4/5/6/7 devices have two software programmable power management modes: idle,
and stop. Idle mode halts the CPU while leaving the peripherals and clocks active. In stop mode, the CPU
is halted, all interrupts and timers (except the missing clock detector) are inactive, and the internal oscilla-
tor is stopped (analog peripherals remain in their selected states; the external oscillator is not affected).
Since clocks are running in idle mode, power consumption is dependent upon the system clock frequency
and the number of peripherals left in active mode before entering Idle. Stop mode consumes the least
power because the majority of the device is shut down with no clocks active. SFR Definition 18.1 describes
the Power Control Register (PCON) used to control the C8051T610/1/2/3/4/5/6/7's stop and idle power
management modes.
Although the C8051T610/1/2/3/4/5/6/7 has idle and stop 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.
18.1. 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.
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-
nitely, waiting for an external stimulus to wake up the system. Refer to Section “19.6. PCA Watchdog Timer
Reset” on page 104 for more information on the use and configuration of the WDT.
Rev 1.1
97
C8051T610/1/2/3/4/5/6/7
18.2. 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.
By default, when in stop mode the internal regulator is still active. However, the regulator can be config-
ured to shut down while in stop mode to save power. To shut down the regulator in stop mode, the
STOPCF bit in register REG0CN should be set to 1 prior to setting the STOP bit (see SFR Definition 11.1).
If the regulator is shut down using the STOPCF bit, only the RST pin or a full power cycle are capable of
resetting the device.
98
Rev 1.1
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SFR Definition 18.1. 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
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 Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts,
Serial Ports, and Analog Peripherals are still active.)
Rev 1.1
99
C8051T610/1/2/3/4/5/6/7
19. 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)
SWRSF
EN
EN
Illegal
EPROM
Operation
Low
Frequency
Oscillator
Internal
Oscillator
System
Clock
CIP-51
Microcontroller
Core
System Reset
External
Oscillator
Drive
EXTCLK
Clock Select
Extended Interrupt
Handler
Figure 19.1. Reset Sources
100
Rev 1.1
C8051T610/1/2/3/4/5/6/7
19.1. 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 19.2. plots the
RST
DD
DD
power-on and V
monitor event 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 0.3 ms.
PORDelay
On exit from a power-on or V monitor reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1.
DD
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 con-
tent of internal data memory should be assumed to be undefined after a power-on reset. The V monitor
DD
is enabled following a power-on reset.
VDD
VRST
t
RST
Logic HIGH
TPORDelay
Logic LOW
VDD
Power-On
Reset
Monitor
Reset
Figure 19.2. Power-On and V Monitor Reset Timing
DD
Rev 1.1
101
C8051T610/1/2/3/4/5/6/7
19.2. 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 19.2). When V returns
DD
to a level above V
, the CIP-51 will be released from the reset state. Note that even though internal data
RST
memory contents are not altered by the power-fail reset, it is impossible to determine if V dropped below
DD
the level required for data retention. If the PORSF flag reads 1, the data may no longer be valid. The V
DD
monitor is 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
DD
V
monitor will still be disabled after the reset.
DD
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 (see Table 7.4 for the V Monitor turn-on time).
DD
DD
3. Select the V monitor as a reset source (PORSF bit in RSTSRC = 1).
DD
See Figure 19.2 for V
monitor timing; note that the power-on-reset delay is not incurred after a V
DD
DD
monitor reset. See Table 7.4 for complete electrical characteristics of the V monitor.
DD
102
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 19.1. 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
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 19.2). 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. See Table 7.4 for the minimum V Monitor turn-on time.
DD
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.
19.3. 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 Table 7.4 for complete RST pin spec-
ifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
19.4. 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 the missing clock detector timeout, the one-shot will 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; writ-
ing a 0 disables it. The state of the RST pin is unaffected by this reset.
Rev 1.1
103
C8051T610/1/2/3/4/5/6/7
19.5. 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.
19.6. PCA Watchdog Timer Reset
The programmable watchdog timer (WDT) function of the programmable counter array (PCA) can be used
to prevent software from running out of control during a system malfunction. The PCA WDT function can
be enabled or disabled by software as described in Section “26.4. Watchdog Timer Mode” on page 200;
the WDT is enabled and clocked by SYSCLK/12 following any reset. If a system malfunction prevents user
software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to 1. The
state of the RST pin is unaffected by this reset.
19.7. EPROM Error Reset
If an EPROM read or write targets an illegal address, a system reset is generated. This may occur due to
any of the following:
Programming hardware attempts to write or read an EPROM location which is above the user code
space address limit.
An EPROM read from firmware is attempted above user code space. This occurs when a MOVC
operation is attempted above the user code space address limit.
A Program read is attempted above user code space. This occurs when user code attempts to branch
to an address above the user code space address limit.
The MEMERR bit (RSTSRC.6) is set following an EPROM error reset. The state of the RST pin is unaf-
fected by this reset.
19.8. 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.
104
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 19.2. RSTSRC: Reset Source
Bit
7
6
5
4
3
2
1
0
MEMERR 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
Bit
Name
Unused Unused.
MEMERR EPROM Error Reset Flag.
Description
Write
Read
7
Don’t care.
N/A
0
6
Set to 1 if EPROM
read/write error caused
the last reset.
5
4
3
2
C0RSEF Comparator0 Reset Enable Writing a 1 enables
Set to 1 if Comparator0
caused the last reset.
and Flag.
Comparator0 as a reset
source (active-low).
SWRSF Software Reset Force and
Writing a 1 forces a sys-
tem reset.
Set to 1 if last reset was
caused by a write to
SWRSF.
Flag.
WDTRSF Watchdog Timer Reset Flag. N/A
Set to 1 if Watchdog Timer
overflow caused the last
reset.
MCDRSF Missing Clock Detector
Writing a 1 enables the
Missing Clock Detector.
Set to 1 if Missing Clock
Detector timeout caused
Enable and Flag.
The MCD triggers a reset the last reset.
if a missing clock condition
is detected.
1
PORSF Power-On/V Monitor
Writing a 1 enables the
monitor as a reset
source.
Set to 1 anytime a power-
DD
V
on or V monitor reset
Reset Flag, and V monitor
DD
DD
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 HW Pin Reset Flag.
N/A
Set to 1 if RST pin caused
the last reset.
Note: Do not use read-modify-write operations on this register
Rev 1.1
105
C8051T610/1/2/3/4/5/6/7
20. Oscillators and Clock Selection
C8051T610/1/2/3/4/5/6/7 devices include a programmable internal high-frequency oscillator and an exter-
nal oscillator drive circuit. The internal high-frequency oscillator can be enabled/disabled and calibrated
using the OSCICN and OSCICL registers, as shown in Figure 20.1. The system clock can be sourced by
the external oscillator circuit or the internal oscillator. The internal oscillator also offers a selectable post-
scaling feature.
OSCICL
OSCICN
RC Mode
VDD
EXTCLK
ProgrammableEN
n
Internal Clock
Generator
SYSCLK
C Mode
Input
Circuit
EXTCLK
EXTCLK
OSC
CMOS Mode
EXTCLK
OSCXCN
CLKSEL
Figure 20.1. Oscillator Options
20.1. System Clock Selection
The CLKSL0 bit in register CLKSEL selects which oscillator source is used as the system clock. CLKSL0
must be set to 1 for the system clock to run from the external oscillator; however the external oscillator may
still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The
system clock may be switched on-the-fly between the internal oscillator and external oscillator, so long as
the selected clock source is enabled and running.
The internal high-frequency oscillator requires little start-up time and may be selected as the system clock
immediately following the register write which enables the oscillator. The external RC and C modes also
typically require no startup time.
106
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 20.1. CLKSEL: Clock Select
Bit
7
6
5
4
3
2
1
0
CLKSL0
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R/W
0
SFR Address = 0xA9
Bit
7:1
0
Name
Unused
CLKSL0
Function
Unused. Read = 0000000b; Write = Don’t Care
System Clock Source Select Bit.
0: SYSCLK derived from the Internal High-Frequency Oscillator and scaled per the
IFCN bits in register OSCICN.
1: SYSCLK derived from the External Oscillator circuit.
Rev 1.1
107
C8051T610/1/2/3/4/5/6/7
20.2. Programmable Internal High-Frequency (H-F) Oscillator
All C8051T610/1/2/3/4/5/6/7 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 20.2.
On C8051T610/1/2/3/4/5/6/7 devices, OSCICL is factory calibrated to obtain a 24.5 MHz base frequency.
The system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as
defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
SFR Definition 20.2. OSCICL: Internal H-F Oscillator Calibration
Bit
7
6
5
4
3
2
1
0
OSCICL[6:0]
Name
Type
Reset
R
0
R/W
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Address = 0xB3
Bit
Name
Function
7
Unused
Unused. Read = 0; Write = Don’t Care
6:0 OSCICL[6:0]
Internal Oscillator Calibration Bits.
These bits determine the internal oscillator period. When set to 0000000b, the H-F
oscillator operates at its fastest setting. When set to 1111111b, 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.
108
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 20.3. OSCICN: Internal H-F Oscillator Control
Bit
7
6
5
4
3
2
1
0
IOSCEN
IFRDY
IFCN[1:0]
R/W
Name
Type
Reset
R/W
1
R
1
R
0
R
0
R
0
R
0
0
0
SFR Address = 0xB2
Bit
Name
Function
7
IOSCEN
Internal H-F Oscillator Enable Bit.
0: Internal H-F Oscillator Disabled.
1: Internal H-F Oscillator Enabled.
6
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.
5:2
1:0
Unused
Unused. Read = 0000b; Write = Don’t Care
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.
Rev 1.1
109
C8051T610/1/2/3/4/5/6/7
20.3. External Oscillator Drive Circuit
The external oscillator circuit may drive an external capacitor or RC network. A CMOS clock may also pro-
vide a clock input. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the
EXTCLK pin as shown in Figure 20.1. The type of external oscillator must be selected in the OSCXCN reg-
ister, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 20.4).
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 capacitor, RC, or CMOS clock
mode, Port pin P0.3 is used as EXTCLK. The Port I/O Crossbar should be configured to skip the Port pin
used by the oscillator circuit; see Section “21.3. Priority Crossbar Decoder” on page 117 for Crossbar con-
figuration. Additionally, when using the external oscillator circuit in capacitor or RC mode, the associated
Port pin should be configured as an analog input. In CMOS clock mode, the associated pin should be
configured as a digital input. See Section “21.4. Port I/O Initialization” on page 121 for details on Port
input mode selection.
110
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 20.4. OSCXCN: External Oscillator Control
Bit
7
6
5
4
3
2
1
0
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 = 0xB1
Bit
Name
Function
7
Unused
Read = 0b; Write = Don’t Care
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 with divide by 2 stage.
101: Capacitor Oscillator Mode with divide by 2 stage.
11x: Reserved.
3
Unused
Read = 0b; Write = Don’t Care
2:0
XFCN[2:0]
External Oscillator Frequency Control Bits.
Set according to the desired frequency range for RC mode.
Set according to the desired K Factor for C mode.
XFCN RC Mode
C Mode
000
001
010
011
100
101
110
111
f 25 kHz
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
25 kHz f 50 kHz
50 kHz f 100 kHz
100 kHz f 200 kHz
200 kHz f 400 kHz
400 kHz f 800 kHz
800 kHz f 1.6 MHz
1.6 MHz f 3.2 MHz
Rev 1.1
111
C8051T610/1/2/3/4/5/6/7
20.3.1. 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 20.1, “RC Mode”. 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 20.1,
where f = the frequency of oscillation in MHz, C = the capacitor value in pF, and R = the pull-up resistor
value in k.
Equation 20.1. 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 20.4, the required XFCN setting is 010b.
20.3.2. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 20.1, “C Mode”. 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 20.2, where f = the frequency of
oscillation in MHz, C = the capacitor value in pF, and V = the MCU power supply in Volts.
DD
Equation 20.2. C Mode Oscillator Frequency
f = KF C 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 20.4
(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.
112
Rev 1.1
C8051T610/1/2/3/4/5/6/7
21. Port Input/Output
Digital and analog resources are available through 29 I/O pins organized as three byte-wide ports and one
5-bit-wide port on the C8051T610/2/4. The C8051T611/3/5 devices have 25 I/O pins available, organized
as three byte-wide ports and one 1-bit-wide port. The C8051T616/7 have 21 I/O pins available on a single
byte-wide port, two 6-bit-wide ports, and a 1-bit-wide port.
Port pins 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 21.3. Port pin P3.0 is shared with the C2 Interface
Data signal (C2D). 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 Prior-
ity Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corresponding Port
latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 21.3, Figure 21.4, and Figure 21.5). The registers XBR0 and XBR1, defined in SFR Definition 21.1
and SFR Definition 21.2, are used to select internal digital functions.
All Port I/O pins are 5 V tolerant (refer to Figure 21.2 for the Port cell circuit). The Port I/O cells are config-
ured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2,3).
Complete Electrical Specifications for Port I/O are given in Table 7.3 on page 33.
XBR0, XBR1,
PnSKIP
External
Interrupts
Registers
EX0 and EX1
PnMDOUT,
PnMDIN
Registers
Priority
Decoder
P0.0
P0.7
2
P0
I/O
Cells
8
UART
SPI
Highest
Priority
4
2
SMBus
P1.0
P1.7
Digital
Crossbar
P1
I/O
Cells
8
4
CP0,
CP1
Outputs
4
SYSCLK
PCA
P2.0
P2.7
P2
I/O
Cells
6
2
4
5
Lowest
Priority
T0, T1
P3.0
P3.4
P3
I/O
Cells
8
P0
P1
(P0.0-P0.7)
8
(P1.0-P1.7)
4
(P2.0-P2.3)
To Analog
Peripherals
P2
4
(P2.4-P2.7)
5
P3
(P3.0-P3.4)
Figure 21.1. Port I/O Functional Block Diagram
Rev 1.1
113
C8051T610/1/2/3/4/5/6/7
21.1. Port I/O Modes of Operation
Port pins use the Port I/O cell shown in Figure 21.2. 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).
21.1.1. Port Pins Configured for Analog I/O
Any pins to be used as Comparator or ADC input, external oscillator input/output, or VREF should be con-
figured 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 configured 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 inputs may still be used by analog peripherals; however, this practice is not recom-
mended and may result in measurement errors.
21.1.2. Port Pins Configured For Digital I/O
Any pins to be used by digital peripherals (UART, SPI, SMBus, etc.), external digital event capture func-
tions, 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 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.
114
Rev 1.1
C8051T610/1/2/3/4/5/6/7
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)
(0 for analog)
GND
To/From Analog
Peripheral
Px.x – Input Logic Value
(Reads 0 when pin is configured as an analog I/O)
Figure 21.2. Port I/O Cell Block Diagram
21.1.3. Interfacing Port I/O to 5V Logic
All Port I/O configured for digital, open-drain operation are capable of interfacing to digital logic operating at
a supply voltage higher than VDD and less than 5.25 V. An external pullup resistor to the higher supply
voltage on output pins is typically required for most systems.
Important Notes: The absolute maximum voltage of any Port I/O pin should be limited to VDD + 3.6V.
When interfacing to systems with supply voltages higher than 3.6V, care must be taken to limit the voltage
on I/O pins when the VDD supply to the device is not present. In a multi-voltage interface, the external pul-
lup 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 + 0.6 V) and (VDD + 1.0 V). Once the Port pin voltage increases beyond this
range, the current flowing into the Port pin is minimal.
Rev 1.1
115
C8051T610/1/2/3/4/5/6/7
21.2. Assigning Port I/O Pins to Analog and Digital Functions
Port I/O pins 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 digital or exter-
nal interrupt functions should be configured for digital I/O.
21.2.1. Assigning Port I/O Pins to Analog Functions
Table 21.1 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 21.1 shows the
potential mapping of Port I/O to each analog function.
Table 21.1. Port I/O Assignment for Analog Functions
Analog Function
PotentiallyAssignable
Port Pins
SFR(s) used for
Assignment
ADC Input
P1.0–P3.4
P1.0–P2.7
AMX0P, PnSKIP
Comparator Inputs
CPT0MX, CPT1MX,
PnSKIP
Voltage Reference (VREF0)
P0.0
P0.3
REF0CN, PnSKIP
OSCXCN, PnSKIP
External Oscillator in RC or C Mode (EXTCLK)
21.2.2. 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 21.2 shows all available digital functions and the potential mapping of Port I/O to each digital
function.
Table 21.2. 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
XBR0, XBR1
CP0A, CP1, CP1A,
SYSCLK, PCA0 (CEX0-4
and ECI), T0 or T1.
Crossbar. This includes P0.0 - P2.3 pins which
have their PnSKIP bit set to 0.
Note: The Crossbar will always assign UART0
pins to P0.4 and P0.5.
Any pin used for GPIO
P0.0–P3.4
PnSKIP
116
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21.2.3. Assigning Port I/O Pins to INT0 or INT1 external interrupts
INT0 and INT1 can be used to trigger an interrupt on any Port 0 I/O pin. These functions do not require
dedicated pins, meaning that they can function on both GPIO pins (PnSKIP = 1) and pins in use by the
crossbar (PnSKIP = 0). INT0 and INT1 cannot be used on pins configured for analog I/O. Table 21.3 shows
the available external digital event capture functions.
Table 21.3. Port I/O Assignment for INT0 and INT1 Functions
Digital Function
Potentially Assignable Port Pins
SFR(s) used for
Assignment
External Interrupt 0 (INT0)
External Interrupt 1 (INT1)
P0.0–P0.7
P0.0–P0.7
IT01CF
IT01CF
21.3. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 21.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that
are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.3 if the
external oscillator circuit is enabled, P0.6 if the ADC is configured to use the external conversion start sig-
nal (CNVSTR), and any selected ADC or Comparator inputs. The Crossbar skips selected pins as if they
were already assigned, and moves to the next unassigned pin. Figure 21.3 shows the potential pin assig-
ments available to the crossbar peripherals. Figure 21.4 and Figure 21.5 show two example crossbar con-
figurations, with and without skipping pins.
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note
that when a peripheral is selected, the crossbar assigns all pins for that peripheral. UART0 pin assign-
ments 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.
Rev 1.1
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Port
P0
P1
P2
Pin Number 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3
Special
Function
Signals
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Pin Skip
Settings
P0SKIP
P1SKIP
P2SKIP
Pins P0.0-P2.3 are capable of being assigned to crossbar peripherals.
The crossbar peripherals are assigned in priority order from top to bottom, according to this
diagram.
These boxes represent Port pins which can potentially be assigned to a peripheral.
Special Function Signals are not assigned by the crossbar. When these signals are
enabled, the Crossbar should be manually configured to skip the corresponding port pins.
Pins can be “skipped” by setting the corresponding bit in PnSKIP to ‘1’.
* NSS is only pinned out when the SPI is in 4-wire mode.
Figure 21.3. Priority Crossbar Decoder Potential Pin Assignments
118
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Port
P0
4
P1
4
P2
Pin Number 0
1
2
3
5
6
7
0
1
2
3
5
6
7
0
1
2
3
Special
Function
Signals
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Pin Skip
Settings
P0SKIP
P1SKIP
P2SKIP
In this example, the crossbar is configured to assign the UART TX0 and RX0 signals, the
SMBus signals, and the SYSCLK signal. Note that the SMBus signals are assigned as a
pair, and there are no pins skipped using the XBR0 register.
These boxes represent the port pins which are used by the peripherals in this
configuration.
1st TX0 is assigned to P0.4
2
nd RX0 is assigned to P0.5
3rd SDA and SCL are assigned to P0.0 and P0.1, respectively.
4th SYSCLK is assigned to P0.2
All unassigned pins can be used as GPIO or for other non-crossbar functions.
Figure 21.4. Priority Crossbar Decoder Example 1 - No Skipped Pins
Rev 1.1
119
C8051T610/1/2/3/4/5/6/7
Port
P0
4
P1
4
P2
Pin Number 0
1
2
3
5
6
7
0
1
2
3
5
6
7
0
1
2
3
Special
Function
Signals
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Pin Skip
Settings
P0SKIP
P1SKIP
P2SKIP
In this example, the crossbar is configured to assign the UART TX0 and RX0 signals, the
SMBus signals, and the SYSCLK signal. Note that the SMBus signals are assigned as a
pair. Additionally, pins P0.0 and P0.3 are configured to be skipped using the XBR0 register.
These boxes represent the port pins which are used by the peripherals in this
configuration.
1st TX0 is assigned to P0.4
2nd RX0 is assigned to P0.5
3rd SDA and SCL are assigned to P0.2 and P0.3, respectively.
4th SYSCLK is assigned to P0.6
All unassigned pins, including those skipped by XBR0 can be used as GPIO or for other non-
crossbar functions.
Figure 21.5. Priority Crossbar Decoder Example 2 - Skipping Pins
120
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21.4. 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). Pins used as input should be set to open-drain.
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
21.4 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 available at the Silicon Labs web site will deter-
mine the Port I/O pin-assignments based on the XBRn register settings.
The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers
are disabled while the Crossbar is disabled.
Rev 1.1
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SFR Definition 21.1. XBR0: Port I/O Crossbar Register 0
Bit
7
6
5
4
3
2
1
0
CP1AE
CP1E
CP0AE
CP0E
SYSCKE
SMB0E
SPI0E
URT0E
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 = 0xE1
Bit
Name
Function
7
CP1AE Comparator1 Asynchronous Output Enable.
0: Asynchronous CP1 unavailable at Port pin.
1: Asynchronous CP1 routed to Port pin.
6
5
4
3
2
1
CP1E
Comparator1 Output Enable.
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
CP0AE Comparator0 Asynchronous Output Enable.
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin.
CP0E
Comparator0 Output Enable.
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
SYSCKE /SYSCLK Output Enable.
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
SMB0E SMBus I/O Enable.
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
SPI0E
SPI I/O Enable.
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins. 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.
122
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SFR Definition 21.2. 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
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 1.1
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21.5. 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.
SFR Definition 21.3. 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; 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
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
HIGH.
HIGH.
124
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SFR Definition 21.4. 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
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.
SFR Definition 21.5. 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
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 pin is open-drain.
1: Corresponding P0.n pin is push-pull.
Rev 1.1
125
C8051T610/1/2/3/4/5/6/7
SFR Definition 21.6. 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
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.
SFR Definition 21.7. 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; 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
HIGH. HIGH.
Read
7:0
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
Note: P1.6 and P1.7 are not connected to external pins on the C8051T616/7 devices.
126
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SFR Definition 21.8. 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
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.
Note: P1.6 and P1.7 are not connected to external pins on the C8051T616/7 devices.
SFR Definition 21.9. 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
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 pin is open-drain.
1: Corresponding P1.n pin is push-pull.
Note: P1.6 and P1.7 are not connected to external pins on the C8051T616/7 devices.
Rev 1.1
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C8051T610/1/2/3/4/5/6/7
SFR Definition 21.10. P1SKIP: Port 1 Skip
Bit
7
6
5
4
3
2
1
0
Name
Type
Reset
P1SKIP[7:0]
R/W
0
0
0
0
0
0
0
0
SFR Address = 0xD5
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.
Note: P1.6 and P1.7 are not connected to external pins on the C8051T616/7 devices. When writing code for the
C8051T616/7, P1SKIP[6:7] should be set to 11b to skip these two pins on the crossbar.
SFR Definition 21.11. 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; 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.
Note: P2.6 and P2.7 are not connected to external pins on the C8051T616/7 devices.
128
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SFR Definition 21.12. 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
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.
Note: P2.6 and P2.7 are not connected to external pins on the C8051T616/7 devices.
SFR Definition 21.13. 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
Bit Name
Function
7:0 P2MDOUT[7:0] Output Configuration Bits for P2.7–P2.0 (respectively).
0: Corresponding P2.n pin is open-drain.
1: Corresponding P2.n pin is push-pull.
Note: P2.6 and P2.7 are not connected to external pins on the C8051T616/7 devices.
Rev 1.1
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SFR Definition 21.14. P2SKIP: Port 2 Skip
Bit
7
6
5
4
3
2
1
0
Name
Type
Reset
P2SKIP[3:0]
R/W
R
0
0
0
0
0
0
0
0
SFR Address = 0xD6
Bit
7:4
3:0
Name
Function
Unused
Unused. Read = 0000b; Write = Don’t Care.
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.
Note: Only P2.0-P2.3 are associated with the crossbar.
SFR Definition 21.15. P3: Port 3
Bit
7
6
5
4
3
2
1
0
P3[4:0]
Name
Type
Reset
R
0
R
0
R
0
R/W
1
1
1
1
1
SFR Address = 0xB0; Bit-Addressable
Bit
7:5
4:0
Name
Description
Write
Read
Unused Unused. Read = 000b; Write = Don’t Care.
P3[4:0] Port 3 Data. 0: Set output latch to logic 0: P3.n Port pin is logic
LOW. LOW.
Sets the Port latch logic
1: Set output latch to logic 1: P3.n Port pin is logic
HIGH. HIGH.
value or reads the Port pin
logic state in Port cells con-
figured for digital I/O.
Note: P3.1-P3.4 are not connected to external pins on the C8051T611/3/5 and C8051T616/7 devices.
130
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SFR Definition 21.16. P3MDIN: Port 3 Input Mode
Bit
7
6
5
4
3
2
1
0
P3MDIN[4:0]
Name
Type
Reset
R/W
1
0
0
0
1
1
1
1
SFR Address = 0xF4
Bit
7:5
4:0
Name
Function
Unused
Unused. Read = 000b; Write = Don’t Care.
P3MDIN[4:0] Analog Configuration Bits for P3.4–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.
Note: P3.1-P3.4 are not connected to external pins on the C8051T611/3/5 and C8051T616/7 devices.
SFR Definition 21.17. P3MDOUT: Port 3 Output Mode
Bit
7
6
5
4
3
2
1
0
P3MDOUT[4:0]
Name
Type
Reset
R/W
0
0
0
0
0
0
0
0
SFR Address = 0xA7
Bit
Name
Function
7:5
Unused
Unused. Read = 000b; Write = Don’t Care.
4:0 P3MDOUT[4:0]
Output Configuration Bits for P3.4–P3.0 (respectively).
0: Corresponding P3.n pin is open-drain.
1: Corresponding P3.n pin is push-pull.
Note: P3.1-P3.4 are not connected to external pins on the C8051T611/3/5 and C8051T616/7 devices.
Rev 1.1
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22. 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. A block diagram of the SMBus peripheral and
the associated SFRs is shown in Figure 22.1.
SMB0CN
SMB0CF
M T S S A A A S
A X T T C R C I
S M A O K B K
E
I
B E S S S S
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
FILTER
Interrupt
Request
Arbitration
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
SCL
Control
C
R
O
S
S
B
A
R
N
IRQ Generation
Port I/O
Data Path
Control
SDA
Control
SMB0DAT
7 6 5 4 3 2 1 0
SDA
FILTER
N
Figure 22.1. SMBus Block Diagram
132
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22.1. 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.
22.2. SMBus Configuration
Figure 22.2 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 22.2. Typical SMBus Configuration
22.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Bytes that are
received (by a master or slave) are acknowledged (ACK) with a low SDA during a high SCL (see
Figure 22.3). 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 1.1
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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 22.3 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 22.3. SMBus Transaction
22.3.1. 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.
22.3.2. 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 “22.3.5. SCL High (SMBus Free) Timeout” on
page 135). 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.
22.3.3. 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.
22.3.4. 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.
134
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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.
22.3.5. 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.
22.4. 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
SMBus interrupts are generated for each data byte or slave address that is transferred. When a transmitter
(i.e., sending address/data, receiving an ACK), this interrupt is generated after the ACK cycle so that soft-
ware 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. See Section 22.5 for more details on transmission sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section 22.4.2;
Table 22.4 provides a quick SMB0CN decoding reference.
22.4.1. 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 1.1
135
C8051T610/1/2/3/4/5/6/7
Table 22.1. 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 22.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “25. Timers” on page 170.
1
---------------------------------------------
THighMin = TLowMin
=
fClockSourceOverflow
Equation 22.1. 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 22.1. 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 22.2.
fClockSourceOverflow
---------------------------------------------
BitRate =
3
Equation 22.2. Typical SMBus Bit Rate
Figure 22.4 shows the typical SCL generation described by Equation 22.2. 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 22.1.
Timer Source
Overflows
SCL
TLow
THigh
SCL High Timeout
Figure 22.4. 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
136
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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 22.2 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 22.2. 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 “22.3.4. SCL Low Timeout” on page 134). 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 22.4).
Rev 1.1
137
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SFR Definition 22.1. 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
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 22.2.
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 22.1.
00: Timer 0 Overflow
01: Timer 1 Overflow
10: Timer 2 High Byte Overflow
11: Timer 2 Low Byte Overflow
138
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22.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 22.2). 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.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating
that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing
value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit
before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit;
however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further
slave events will be ignored until the next START is detected.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error 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 22.3 for more details.
Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 22.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 22.4 for SMBus sta-
tus decoding using the SMB0CN register.
Rev 1.1
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SFR Definition 22.2. 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; Bit-Addressable
Bit
Name
Description
Read
Write
7
MASTER SMBus Master/Slave
Indicator. This read-only bit
indicates when the SMBus is
operating as a master.
0: SMBus operating in
slave mode.
1: SMBus operating in
master mode.
N/A
N/A
6
5
4
TXMODE SMBus Transmit Mode
Indicator. This read-only bit
indicates when the SMBus is
operating as a transmitter.
0: SMBus in Receiver
Mode.
1: SMBus in Transmitter
Mode.
STA
SMBus Start Flag.
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.
STO
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
Request.
ARBLOST SMBus Arbitration Lost
0: No arbitration error.
1: Arbitration Lost
N/A
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.
140
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Table 22.3. 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.
MASTER
START is generated.
A START is detected.
Arbitration is lost.
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.
Must be cleared by software.
STA
STO
A STOP is detected while addressed as a
slave.
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).
After each ACK cycle.
Each time SI is cleared.
ACKRQ
A repeated START is detected as a
MASTER when STA is low (unwanted
repeated START).
SCL is sensed low while attempting to
generate a STOP or repeated START
condition.
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).
A START has been generated.
Lost arbitration.
Must be cleared by software.
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.
Rev 1.1
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22.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbi-
tration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 22.3. 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
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.
142
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22.5. 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. As a receiver, the interrupt for an ACK occurs before the ACK. As a transmitter,
interrupts occur after the ACK.
22.5.1. 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. Note that the interface
will switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 22.5 shows a typical master write sequence. Two transmit data bytes are shown, though any num-
ber of bytes may be transmitted. Notice that all of the “data byte transferred” interrupts occur after the ACK
cycle in this mode.
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt Locations
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
Transmitted by
SLA = Slave Address
SMBus Interface
Figure 22.5. Typical Master Write Sequence
Rev 1.1
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22.5.2. 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.
The ACKRQ bit 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.
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 22.6 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 before the ACK.
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt Locations
S = START
P = STOP
A = ACK
Received by SMBus
Interface
N = NACK
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 22.6. Typical Master Read Sequence
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22.5.3. 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. 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 the received slave address is ignored by software (by NACKing the address), 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.
The ACKRQ bit 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.
The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 22.7 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 before the ACK.
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt Locations
S = START
Received by SMBus
Interface
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 22.7. Typical Slave Write Sequence
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22.5.4. 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. 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 the received slave address is ignored by software (by NACKing the address), slave interrupts will be
inhibited until the next START is detected. If the received slave address is acknowledged, zero or more
data bytes are transmitted. If the received slave address is acknowledged, data should be written to
SMB0DAT to be transmitted. The interface enters slave transmitter mode, and transmits one or more bytes
of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an
ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT
should not be written to before SI is cleared (an error condition may be generated if SMB0DAT is written
following a received NACK while in slave transmitter mode). The interface exits slave transmitter mode
after receiving a STOP. Note that the interface will switch to slave receiver mode if SMB0DAT is not written
following a Slave Transmitter interrupt. Figure 22.8 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.
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt Locations
S = START
Received by SMBus
Interface
P = STOP
N = NACK
R = READ
Transmitted by
SMBus Interface
SLA = Slave Address
Figure 22.8. Typical Slave Read Sequence
22.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. Table 22.4 describes the
typical actions taken by firmware on each condition. In the table, STATUS VECTOR refers to the four upper
bits of SMB0CN: MASTER, TXMODE, STA, and STO. The shown response options are only the typical
responses; application-specific procedures are allowed as long as they conform to the SMBus specifica-
tion. Highlighted responses are allowed by hardware but do not conform to the SMBus specification.
146
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Table 22.4. SMBus Status Decoding
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
1100
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
—
—
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 1.1
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Table 22.4. SMBus Status Decoding
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
1
—
ing a STOP.
complete/aborted).
Acknowledge received byte;
Read SMB0DAT.
0000
A slave byte was received;
ACK requested.
1
0
X
NACK received byte.
Abort failed transfer.
0
0
1
0
1
0
1
0
0
0
0
0
0
0
0
X
X
X
X
0
—
—
Lost arbitration while attempt-
ing a repeated START.
0010
0001
0
0
1
1
X
X
Reschedule failed transfer.
Abort failed transfer.
1110
—
Lost arbitration due to a
detected STOP.
Reschedule failed transfer.
Abort failed transfer.
1110
—
Lost arbitration while transmit-
ting a data byte as master.
0000
1
1
X
0
1110
Reschedule failed transfer.
148
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23. 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 “23.1. Enhanced Baud Rate Generation” on page 150). 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
Send
Start
Tx Control
Tx Clock
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 23.1. UART0 Block Diagram
Rev 1.1
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23.1. 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 23.2), 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 23.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “25.1.3. Mode 2: 8-bit Coun-
ter/Timer with Auto-Reload” on page 174). The Timer 1 reload value should be set so that overflows will
occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six
sources: SYSCLK, SYSCLK/4, SYSCLK/12, SYSCLK/48, the external oscillator clock/8, or an external
input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 23.1-A and
Equation 23.1-B.
1
2
A)
B)
--
UartBaudRate = T1_Overflow_Rate
T1CLK
-------------------------
T1_Overflow_Rate =
256 – TH1
Equation 23.1. 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 “25. Timers” on page 170. A quick ref-
erence for typical baud rates and system clock frequencies is given in Table 23.1 through Table 23.2. The
internal oscillator may still generate the system clock when the external oscillator is driving Timer 1.
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23.2. 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 23.3.
TX
RS-232
RS-232
LEVEL
C8051xxxx
RX
XLTR
OR
TX
RX
TX
RX
MCU
C8051xxxx
Figure 23.3. UART Interconnect Diagram
23.2.1. 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 23.4. 8-Bit UART Timing Diagram
Rev 1.1
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23.2.2. 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 23.5. 9-Bit UART Timing Diagram
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23.3. 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 23.6. UART Multi-Processor Mode Interconnect Diagram
Rev 1.1
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SFR Definition 23.1. 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; 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.
154
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SFR Definition 23.2. 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
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 1.1
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Table 23.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator
Frequency: 24.5 MHz
1
Target
Baud Rate Oscillator Timer Clock
SCA1–SCA0
Timer 1
Reload
Value (hex)
T1M
% Error
Divide
Factor
Source
Baud Rate
(bps)
(pre-scale
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 25.1.
2. X = Don’t care.
Table 23.2. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator
Frequency: 22.1184 MHz
1
Target
Baud Rate Oscillator Timer Clock
SCA1–SCA0
(pre-scale
Timer 1
Reload
Value (hex)
T1M
% Error
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 25.1.
2. X = Don’t care.
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24. 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 24.1. SPI Block Diagram
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24.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
24.1.1. 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.
24.1.2. 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.
24.1.3. 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.
24.1.4. 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 24.2, Figure 24.3, and Figure 24.4 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 “21. Port Input/Output” on page 113 for general purpose
port I/O and crossbar information.
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24.2. 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 24.2 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 24.3
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 24.4 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 24.2. Multiple-Master Mode Connection Diagram
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Master
Slave
MISO
MISO
MOSI
SCK
Device
Device
MOSI
SCK
Figure 24.3. 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 24.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection
Diagram
24.3. 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. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 24.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
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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 24.3 shows a connection diagram between a slave device in 3-
wire slave mode and a master device.
24.4. 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.
24.5. 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 24.5. For slave mode, the clock and
data relationships are shown in Figure 24.6 and Figure 24.7. Note that 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 24.3 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.
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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 24.5. 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 0
MISO
Bit 1
Bit 0
NSS (4-Wire Mode)
Figure 24.6. Slave Mode Data/Clock Timing (CKPHA = 0)
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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 24.7. Slave Mode Data/Clock Timing (CKPHA = 1)
24.6. 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.
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SFR Definition 24.1. 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
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 24.1 for timing parameters.
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SFR Definition 24.2. 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; 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 24.2 and Section 24.3).
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.
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SFR Definition 24.3. 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
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 24.4. 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
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.
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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 24.8. 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 24.9. SPI Master Timing (CKPHA = 1)
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NSS
T
T
T
SD
SE
CKL
SCK*
T
CKH
T
T
SIH
SIS
MOSI
MISO
T
T
T
SDZ
SEZ
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 24.10. SPI Slave Timing (CKPHA = 0)
NSS
T
T
T
SD
SE
CKL
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 24.11. SPI Slave Timing (CKPHA = 1)
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Table 24.1. SPI Slave Timing Parameters
Parameter
Description
Min
Max
Units
Master Mode Timing (See Figure 24.8 and Figure 24.9)
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 24.10 and Figure 24.11)
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
6 x T
SYSCLK
(CKPHA = 1 ONLY)
Note: T
is equal to one period of the device system clock (SYSCLK).
SYSCLK
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25. 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.
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 25.1 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.
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SFR Definition 25.1. 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
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)
Rev 1.1
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25.1. 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 “16.2. Interrupt Register Descriptions” on page 87); Timer 1 interrupts can be enabled by set-
ting the ET1 bit in the IE register (Section “16.2. Interrupt Register Descriptions” on page 87). 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.
25.1.1. 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
“21.3. Priority Crossbar Decoder” on page 117 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 25.1).
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 16.5). Setting
GATE0 to 1 allows the timer to be controlled by the external input signal INT0 (see Section “16.2. Interrupt
Register Descriptions” on page 87), 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 16.5).
172
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TMOD
IT01CF
G C T T G C T
T
0
I I I I I I I I
N N N N N N N N
1 1 1 1 0 0 0 0
A
T
/
1
1
A
/
0
T0M
T M M T T M M
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
T0
Interrupt
TCLK
TL0
(5 bits)
TH0
(8 bits)
TR0
IT1
GATE0
IE0
IT0
Crossbar
IN0PL
XOR
INT0
Figure 25.1. T0 Mode 0 Block Diagram
25.1.2. 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.
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25.1.3. 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 “16.3. External Interrupts
INT0 and INT1” on page 92 for details on the external input signals INT0 and INT1).
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 25.2. T0 Mode 2 Block Diagram
174
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25.1.4. 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.
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 25.3. T0 Mode 3 Block Diagram
Rev 1.1
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SFR Definition 25.2. 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; 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 16.5).
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 16.5).
0: INT0 is level triggered.
1: INT0 is edge triggered.
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SFR Definition 25.3. 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
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 16.5).
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 16.5).
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
Rev 1.1
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SFR Definition 25.4. 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
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 25.5. 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
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.
178
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SFR Definition 25.6. 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
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 25.7. 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
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.
Rev 1.1
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25.2. 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 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. Note that the external oscillator source divided by 8 is synchronized with the system clock.
25.2.1. 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 25.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled, 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.
T2XCLK
T2ML
To ADC,
SMBus
To SMBus
SYSCLK / 12
0
1
TL2
Overflow
0
1
TCLK
TR2
TF2H
TF2L
TF2LEN
TMR2L
TMR2H
Interrupt
External Clock / 8
SYSCLK
T2SPLIT
TR2
T2XCLK
TMR2RLL TMR2RLH
Reload
Figure 25.4. Timer 2 16-Bit Mode Block Diagram
180
Rev 1.1
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25.2.2. 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 25.5. 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, an interrupt is generated each time TMR2H over-
flows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is generated 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.
T2XCLK
Reload
T2MH
TMR2RLH
To SMBus
SYSCLK / 12
0
1
0
1
External Clock / 8
TCLK
TF2H
TF2L
TF2LEN
TMR2H
Interrupt
TR2
T2SPLIT
TR2
Reload
TMR2RLL
T2ML
T2XCLK
SYSCLK
1
0
To ADC,
SMBus
TCLK
TMR2L
Figure 25.5. Timer 2 8-Bit Mode Block Diagram
Rev 1.1
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SFR Definition 25.8. TMR2CN: Timer 2 Control
Bit
7
6
5
4
3
2
1
0
TF2H
TF2L
TF2LEN
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; 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
5
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.
TF2LEN
Unused
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.
4
3
Unused. Read = 0b; Write = Don’t Care
T2SPLIT 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.
2
TR2
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).
182
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SFR Definition 25.9. 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
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 25.10. 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
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.
SFR Definition 25.11. 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
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.
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SFR Definition 25.12. 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
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.
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25.3. 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 oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external preci-
sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
25.3.1. 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 25.6,
and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled, 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.
T3XCLK
T3ML
To ADC,
SMBus
To SMBus
SYSCLK / 12
0
1
TL3
Overflow
0
1
TCLK
TR3
TF3H
TF3L
TF3LEN
TMR3L
TMR3H
Interrupt
External Clock / 8
SYSCLK
T3SPLIT
TR3
T3XCLK
TMR3RLL TMR3RLH
Reload
Figure 25.6. Timer 3 16-Bit Mode Block Diagram
Rev 1.1
185
C8051T610/1/2/3/4/5/6/7
25.3.2. 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 25.7. 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.
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 bit (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.
T3XCLK
Reload
T3MH
TMR3RLH
To SMBus
SYSCLK / 12
0
1
0
1
External Clock / 8
TCLK
TF3H
TF3L
TF3LEN
TMR3H
Interrupt
TR3
T3SPLIT
TR3
Reload
TMR3RLL
T3ML
T3XCLK
To ADC
SYSCLK
1
0
TCLK
TMR3L
Figure 25.7. Timer 3 8-Bit Mode Block Diagram
186
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 25.13. TMR3CN: Timer 3 Control
Bit
7
6
5
4
3
2
1
0
TF3H
TF3L
TF3LEN
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; Bit-Addressable
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
5
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.
TF3LEN
Unused
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.
4
3
Unused. Read = 0b; Write = Don’t Care
T3SPLIT 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.
2
TR3
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: Timer 3 clock is the system clock divided by 12.
1: Timer 3 clock is the external clock divided by 8 (synchronized with SYSCLK).
Rev 1.1
187
C8051T610/1/2/3/4/5/6/7
SFR Definition 25.14. 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
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 25.15. 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
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.
SFR Definition 25.16. 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
Bit Name
7:0 TMR3L[7:0] Timer 3 Low Byte.
Function
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.
188
Rev 1.1
C8051T610/1/2/3/4/5/6/7
SFR Definition 25.17. 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
Bit Name
7:0 TMR3H[7:0] Timer 3 Low Byte.
Function
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.
Rev 1.1
189
C8051T610/1/2/3/4/5/6/7
26. 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 five 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 six 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-Bit PWM, or 16-Bit PWM (each mode is described in Section “26.3. Capture/Compare
Modules” on page 193). 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 internal oscillator drives the sys-
tem clock. The PCA is configured and controlled through the system controller's Special Function Regis-
ters. The PCA block diagram is shown in Figure 26.1
Important Note: The PCA Module 4 may be used as a watchdog timer (WDT), and is enabled in this mode
following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled.
See Section 26.4 for details.
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
Capture/Compare
Module 3
Capture/Compare
Module 4 / WDT
Crossbar
Port I/O
Figure 26.1. PCA Block Diagram
190
Rev 1.1
C8051T610/1/2/3/4/5/6/7
26.1. 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 26.1.
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 26.1. PCA Timebase Input Options
CPS2
CPS1
CPS0 Timebase
0
0
0
0
0
1
0
1
0
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)
0
1
1
1
0
0
System clock
*
1
1
0
1
1
x
External oscillator source divided by 8
Reserved
Note: External oscillator source divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
PCA0CN
C WW C C C E
I D D P P P C
D T L S S S F
L E C 2 1 0
K
C C C C C C C
F R C C C C C
F F F F F
4 3 2 1 0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
000
001
Timer 0 Overflow
ECI
010
011
100
101
0
Overflow
To PCA Interrupt System
PCA0H
PCA0L
1
SYSCLK
CF
External Clock/8
To PCA Modules
Figure 26.2. PCA Counter/Timer Block Diagram
Rev 1.1
191
C8051T610/1/2/3/4/5/6/7
26.2. PCA0 Interrupt Sources
Figure 26.3 shows a diagram of the PCA interrupt tree. There are six 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 and the individual flags for each PCA channel (CCF0, CCF1, CCF2,
CCF3, and CCF4), 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, 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 4)
PCA0CPMn
PCA0CN
PCA0MD
P E C C M T P E
WC A A A O WC
MO P P T G M C
1 M P N n n n F
C C C C C C C
F R C C C C C
F F F F F
C WW C C C E
I D D P P P C
D T L S S S F
L E C 2 1 0
K
4 3 2 1 0
6 n n n
n
n
0
1
PCA Counter/Timer 16-
bit Overflow
ECCF0
0
1
PCA Module 0
(CCF0)
ECCF1
ECCF2
ECCF3
ECCF4
0
1
PCA Module 1
(CCF1)
EPCA0
EA
Interrupt
Priority
Decoder
0
1
0
1
0
1
PCA Module 2
(CCF2)
0
1
PCA Module 3
(CCF2)
0
1
PCA Module 4
(CCF2)
Figure 26.3. PCA Interrupt Block Diagram
192
Rev 1.1
C8051T610/1/2/3/4/5/6/7
26.3. 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-bit pulse width modulator, or 16-bit pulse
width modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 sys-
tem controller. These registers are used to exchange data with a module and configure the module's mode
of operation. Table 26.2 summarizes the bit settings in the PCA0CPMn register used to select the PCA
capture/compare module’s operating mode. Setting the ECCFn bit in a PCA0CPMn register enables the
module's CCFn interrupt.
Table 26.2. PCA0CPM Bit Settings for PCA Capture/Compare Modules
Operational Mode
PCA0CPMn
Bit Number 7 6 5 4 3 2 1 0
X X 1 0 0 0 0 A
X X 0 1 0 0 0 A
X X 1 1 0 0 0 A
X B 0 0 1 0 0 A
X B 0 0 1 1 0 A
X B 0 0 0 1 1 A
0 B 0 0 C 0 1 A
1 B 0 0 C 0 1 A
Capture triggered by positive edge on CEXn
Capture triggered by negative edge on CEXn
Capture triggered by any transition on CEXn
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
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 = 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).
4. C = When set, a match event will cause the CCFn flag for the associated channel to be set.
Rev 1.1
193
C8051T610/1/2/3/4/5/6/7
26.3.1. 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
PCA0CN
C C C C C C C
F R C C C C C
F F F F F
WC A A A O WC
M O P P T G M C
1 M P N n n n F
4 3 2 1 0
6 n n n
n
n
x
x
0 0 0 x
PCA0CPLn
PCA0CPHn
0
1
CEXn
Capture
Port I/O
Crossbar
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 26.4. 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.
194
Rev 1.1
C8051T610/1/2/3/4/5/6/7
26.3.2. 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 WC
MO P P T G M C
1 M P N n n n F
PCA0CN
C C C C C C C
F R C C C C C
F F F F F
PCA0CPLn
PCA0CPHn
6 n n n
n
n
4 3 2 1 0
x
0 0
0 0
x
0
1
Enable
Match
16-bit Comparator
PCA
Timebase
PCA0L
PCA0H
Figure 26.5. PCA Software Timer Mode Diagram
Rev 1.1
195
C8051T610/1/2/3/4/5/6/7
26.3.3. 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 WC
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 C C
F R C C C C C
F F F F F
PCA0CPLn
PCA0CPHn
4 3 2 1 0
0
1
Enable
Match
16-bit Comparator
TOGn
Toggle
0
CEXn
Crossbar
Port I/O
1
PCA
Timebase
PCA0L
PCA0H
Figure 26.6. PCA High-Speed Output Mode Diagram
196
Rev 1.1
C8051T610/1/2/3/4/5/6/7
26.3.4. 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 26.1.
FPCA
----------------------------------------
=
FCEXn
2 PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Equation 26.1. 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. Note that 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 channel are equal.
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPMn
P E C C M T P E
WC A A A O WC
M O 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 26.7. PCA Frequency Output Mode
Rev 1.1
197
C8051T610/1/2/3/4/5/6/7
26.3.5. 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 26.8). 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 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 duty cycle for 8-
Bit PWM Mode is given in Equation 26.2.
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 26.2. 8-Bit PWM Duty Cycle
Using Equation 26.2, 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.
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPHn
PCA0CPLn
Write to
PCA0CPHn
ENB
COVF
1
PCA0CPMn
P E C C M T P E
WC A A A O WC
M O P P T G M C
1 M P N n n n F
6 n n n
n
n
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 26.8. PCA 8-Bit PWM Mode Diagram
198
Rev 1.1
C8051T610/1/2/3/4/5/6/7
26.3.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare mod-
ule defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches
the module contents, the output on CEXn is asserted high; when the 16-bit counter overflows, CEXn is
asserted low. To output a varying 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 varying 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 26.3.
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 26.3. 16-Bit PWM Duty Cycle
Using Equation 26.3, 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 WC
MO P P T G M C
1 M P N n n n F
PCA0CPHn
PCA0CPLn
6 n n n
n
n
1
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 26.9. PCA 16-Bit PWM Mode
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26.4. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 4. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH4) exceed a specified
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE bit set in the PCA0MD register, Module 4 operates as a watchdog timer (WDT). The Mod-
ule 4 high byte is compared to the PCA counter high byte; the Module 4 low byte holds the offset to be
used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some
PCA registers are restricted while the Watchdog Timer is enabled. The WDT will generate a reset
shortly after code begins execution. To avoid this reset, the WDT should be explicitly disabled (and option-
ally re-configured and re-enabled if it is used in the system).
26.4.1. Watchdog Timer Operation
While the WDT is enabled:
PCA counter is forced on.
Writes to PCA0L and PCA0H are not allowed.
PCA clock source bits (CPS2–CPS0) are frozen.
PCA Idle control bit (CIDL) is frozen.
Module 4 is forced into software timer mode.
Writes to the Module 4 mode register (PCA0CPM4) are disabled.
While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run
until the WDT is disabled. The PCA counter run control bit (CR) will read zero if the WDT is enabled but
user software has not enabled the PCA counter. If a match occurs between PCA0CPH4 and PCA0H while
the WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a
write of any value to PCA0CPH4. Upon a PCA0CPH4 write, PCA0H plus the offset held in PCA0CPL4 is
loaded into PCA0CPH4 (See Figure 26.10).
PCA0MD
C WW C C C E
I D D P P P C
PCA0CPH4
D T L S S S F
L E C 2 1 0
K
8-bit
Comparator
Match
Reset
Enable
PCA0L Overflow
PCA0CPL4
8-bit Adder
PCA0H
Adder
Enable
Write to
PCA0CPH4
Figure 26.10. PCA Module 4 with Watchdog Timer Enabled
200
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The 8-bit offset held in PCA0CPH4 is compared to the upper byte of the 16-bit PCA counter. This offset
value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the first
PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The total off-
set is then given (in PCA clocks) by Equation 26.4, where PCA0L is the value of the PCA0L register at the
time of the update.
Offset = 256 PCA0CPL4 + 256 – PCA0L
Equation 26.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH4 and
PCA0H. Software may force a WDT reset by writing a 1 to the CCF4 flag (PCA0CN.4) while the WDT is
enabled.
26.4.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
1. Disable the WDT by writing a 0 to the WDTE bit.
2. Select the desired PCA clock source (with the CPS2–CPS0 bits).
3. Load PCA0CPL4 with the desired WDT update offset value.
4. Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle
mode).
5. Enable the WDT by setting the WDTE bit to 1.
6. Reset the WDT timer by writing to PCA0CPH4.
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog
timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the
WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing
the WDTE bit.
The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by
12, PCA0L defaults to 0x00, and PCA0CPL4 defaults to 0x00. Using Equation 26.4, this results in a WDT
timeout interval of 256 PCA clock cycles, or 3072 system clock cycles. Table 26.3 lists some example time-
out intervals for typical system clocks.
Rev 1.1
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1
Table 26.3. Watchdog Timer Timeout Intervals
System Clock (Hz)
PCA0CPL4
Timeout Interval (ms)
24,500,000
24,500,000
24,500,000
255
128
32
32.1
16.2
4.1
2
3,062,500
255
128
257
2
3,062,500
129.5
2
3,062,500
32
255
128
32
33.1
24576
12384
3168
32,000
32,000
32,000
Notes:
1. Assumes SYSCLK/12 as the PCA clock source, and a PCA0L value
of 0x00 at the update time.
2. Internal SYSCLK reset frequency = Internal Oscillator divided by 8.
202
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26.5. Register Descriptions for PCA0
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 26.1. PCA0CN: PCA Control
Bit
7
6
5
4
3
2
1
0
CF
CR
CCF4
CCF3
CCF2
CCF1
CCF0
Name
Type
Reset
R/W
0
R/W
0
R
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
SFR Address = 0xD8; 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
2
Unused Unused. Read = 0b, Write = Don't care.
CCF4
CCF3
CCF2
CCF1
CCF0
PCA Module 4 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt
is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou-
tine. This bit is not automatically cleared by hardware and must be cleared by software.
1
2
1
0
PCA Module 3 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt
is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou-
tine. This bit is not automatically cleared by hardware and must be cleared by software.
PCA Module 2 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt
is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou-
tine. This bit is not automatically cleared by hardware and must be cleared by software.
PCA Module 1 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt
is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou-
tine. This bit is not automatically cleared by hardware and must be cleared by software.
PCA Module 0 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt
is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou-
tine. This bit is not automatically cleared by hardware and must be cleared by software.
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SFR Definition 26.2. PCA0MD: PCA Mode
Bit
7
6
5
4
3
2
1
0
CIDL
WDTE
WDLCK
CPS[2:0]
ECF
Name
Type
Reset
R/W
0
R/W
1
R/W
0
R
0
R/W
0
R/W
0
0
0
SFR Address = 0xD9
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
WDTE Watchdog Timer Enable.
If this bit is set, PCA Module 4 is used as the watchdog timer.
0: Watchdog Timer disabled.
1: PCA Module 4 enabled as Watchdog Timer.
WDLCK Watchdog Timer Lock.
This bit locks/unlocks the Watchdog Timer Enable. When WDLCK is set, the Watchdog
Timer may not be disabled until the next system reset.
0: Watchdog Timer Enable unlocked.
1: Watchdog Timer Enable locked.
4
Unused 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)
11x: 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.
Note: When the WDTE bit is set to 1, the other bits in the PCA0MD register cannot be modified. To change the
contents of the PCA0MD register, the Watchdog Timer must first be disabled.
204
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SFR Definition 26.3. 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: 0xDA (n = 0), 0xDB (n = 1), 0xDC (n = 2), 0xDD (n = 3), 0xDE (n = 4)
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-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-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.
Note: When the WDTE bit is set to 1, the PCA0CPM4 register cannot be modified, and module 4 acts as the
watchdog timer. To change the contents of the PCA0CPM4 register or the function of module 4, the Watchdog
Timer must be disabled.
Rev 1.1
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SFR Definition 26.4. 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
Bit Name
7:0 PCA0[7:0] PCA Counter/Timer Low Byte.
Function
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
Note: When the WDTE bit is set to 1, the PCA0L register cannot be modified by software. To change the contents of
the PCA0L register, the Watchdog Timer must first be disabled.
SFR Definition 26.5. 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
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 26.1).
Note: When the WDTE bit is set to 1, the PCA0H register cannot be modified by software. To change the contents of
the PCA0H register, the Watchdog Timer must first be disabled.
206
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SFR Definition 26.6. 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: 0xFB (n = 0), 0xE9 (n = 1), 0xEB (n = 2), 0xED (n = 3), 0xFD (n = 4)
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.
Note: A write to this register will clear the module’s ECOMn bit to a 0.
SFR Definition 26.7. 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: 0xFC (n = 0), 0xEA (n = 1), 0xEC (n = 2), 0xEE (n = 3), 0xFE (n = 4)
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.
Note: A write to this register will set the module’s ECOMn bit to a 1.
Rev 1.1
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27. C2 Interface
C8051T610/1/2/3/4/5/6/7 devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow
EPROM programming and in-system debugging with the production part installed in the end application.
The C2 interface 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.
27.1. C2 Interface Registers
The following describes the C2 registers necessary to perform EPROM 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 27.1. 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]
Write: C2 Address.
Selects the target Data register for C2 Data Read and Data Write commands accord-
ing to the following list.
Address Name
Description
DEVICEID Selects the Device ID Register (read only)
REVID Selects the Revision ID Register (read only)
DEVCTL Selects the C2 Device Control Register
0x00
0x01
0x02
0xDF
0xBF
0xB7
0xAF
0xAE
0xA9
0xAA
0xAB
0xAC
EPCTL
EPDAT
EPSTAT
Selects the C2 EPROM Programming Control Register
Selects the C2 EPROM Data Register
Selects the C2 EPROM Status Register
EPADDRH Selects the C2 EPROM Address High Byte Register
EPADDRL Selects the C2 EPROM Address Low Byte Register
CRC0
CRC1
CRC2
CRC3
Selects the CRC0 Register
Selects the CRC1 Register
Selects the CRC2 Register
Selects the CRC3 Register
Read: C2 Status
Returns status information on the current programming operation.
When the MSB (bit 7) is set to ‘1’, a read or write operation is in progress. All other
bits can be ignored by the programming tools.
208
Rev 1.1
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C2 Register Definition 27.2. DEVICEID: C2 Device ID
Bit
7
6
5
4
3
2
1
0
DEVICEID[7:0]
R/W
Name
Type
Reset
0
0
0
1
0
0
1
1
C2 Address: 0x00
Bit Name
7:0 DEVICEID[7:0] Device ID.
Function
This read-only register returns the 8-bit device ID: 0x13
(C8051T610/1/2/3/4/5/6/7).
C2 Register Definition 27.3. 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.
This read-only register returns the 8-bit revision ID. For example: 0x00 = Revision A.
Function
Rev 1.1
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C2 Register Definition 27.4. DEVCTL: C2 Device Control
Bit
7
6
5
4
3
2
1
0
DEVCTL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0x02
Bit Name
7:0 DEVCTL[7:0] Device Control Register.
Function
This register is used to halt the device for EPROM operations via the C2 interface.
Refer to the EPROM chapter for more information.
C2 Register Definition 27.5. EPCTL: EPROM Programming Control Register
Bit
7
6
5
4
3
2
1
0
EPCTL[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xDF
Bit Name
7:0 EPCTL[7:0] EPROM Programming Control Register.
Function
This register is used to enable EPROM programming via the C2 interface. Refer to
the EPROM chapter for more information.
210
Rev 1.1
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C2 Register Definition 27.6. EPDAT: C2 EPROM Data
Bit
7
6
5
4
3
2
1
0
EPDAT[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xBF
Bit Name
7:0 EPDAT[7:0] C2 EPROM Data Register.
This register is used to pass EPROM data during C2 EPROM operations.
Function
C2 Register Definition 27.7. EPSTAT: C2 EPROM Status
Bit
7
6
5
4
3
2
1
0
WRLOCK RDLOCK
ERROR
Name
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
C2 Address: 0xB7
Bit
Name
WRLOCK Write Lock Indicator.
Set to 1 if EPADDR currently points to a write-locked address.
RDLOCK Read Lock Indicator.
Function
7
6
Set to 1 if EPADDR currently points to a read-locked address.
5:1
0
Unused
ERROR
Unused. Read = 00000b; Write = don’t care.
Error Indicator.
Set to 1 if last EPROM read or write operation failed due to a security restriction.
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C2 Register Definition 27.8. EPADDRH: C2 EPROM Address High Byte
Bit
7
6
5
4
3
2
1
0
EPADDR[15:8]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xAF
Bit Name
7:0 EPADDR[15:8] C2 EPROM Address High Byte.
Function
This register is used to set the EPROM address location during C2 EPROM oper-
ations.
C2 Register Definition 27.9. EPADDRL: C2 EPROM Address Low Byte
Bit
7
6
5
4
3
2
1
0
EPADDR[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xAE
Bit Name
7:0 EPADDR[15:8] C2 EPROM Address Low Byte.
Function
This register is used to set the EPROM address location during C2 EPROM oper-
ations.
212
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C2 Register Definition 27.10. CRC0: CRC Byte 0
Bit
7
6
5
4
3
2
1
0
CRC[7:0]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xA9
Bit
Name
Function
7:0
CRC[7:0] CRC Byte 0.
A write to this register initiates a 16-bit CRC of one 256-byte block of EPROM mem-
ory. The byte written to CRC0 is the upper byte of the 16-bit address where the CRC
will begin. The lower byte of the beginning address is always 0x00. When complete,
the 16-bit result will be available in CRC1 (MSB) and CRC0 (LSB). See Section
“17.3. Program Memory CRC” on page 96.
C2 Register Definition 27.11. CRC1: CRC Byte 1
Bit
7
6
5
4
3
2
1
0
CRC[15:8]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xAA
Bit Name
7:0 CRC[15:8] CRC Byte 1.
Function
A write to this register initiates a 32-bit CRC on the entire program memory space.
The CRC begins at address 0x0000. When complete, the 32-bit result is stored in
CRC3 (MSB), CRC2, CRC1, and CRC0 (LSB). See Section “17.3. Program Memory
CRC” on page 96.
Rev 1.1
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C2 Register Definition 27.12. CRC2: CRC Byte 2
Bit
7
6
5
4
3
2
1
0
CRC[23:16]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xAB
Bit Name
7:0 CRC[23:16] CRC Byte 2.
See Section “17.3. Program Memory CRC” on page 96.
Function
C2 Register Definition 27.13. CRC3: CRC Byte 3
Bit
7
6
5
4
3
2
1
0
CRC[31:24]
R/W
Name
Type
Reset
0
0
0
0
0
0
0
0
C2 Address: 0xAC
Bit Name
7:0 CRC[31:24] CRC Byte 3.
Function
See Section “17.3. Program Memory CRC” on page 96.
214
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27.2. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and
EPROM programming functions may be performed. This is possible because C2 communication is typi-
cally performed when the device is in the halt state, where all on-chip peripherals and user software are
stalled. In this halted state, the C2 interface can safely “borrow” the C2CK (normally RST) and C2D pins. In
most applications, external resistors are required to isolate C2 interface traffic from the user application
when performing debug functions. These external resistors are not necessary for production boards. A typ-
ical isolation configuration is shown in Figure 27.1.
RST (a)
Input (b)
C2CK
C2D
Output (c)
C2 Interface Master
Figure 27.1. Typical C2 Pin Sharing
The configuration in Figure 27.1 assumes the following:
1. The user input (b) cannot change state while the target device is halted.
2. The RST pin on the target device is used as an input only.
Additional resistors may be necessary depending on the specific application.
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DOCUMENT CHANGE LIST
Revision 0.3 to Revision 1.0
Updated electrical specification tables based on test, characterization, and qualification data.
Updated figures and text to correct minor typographical errors throughout document.
Updated formatting throughout document for new datasheet standards.
Updated package definitions to include all possible vendor information, and JEDEC-standard drawings.
Revision 1.0 to Revision 1.1
Updated EPROM programming recommendations in section 17.1.1 for devices dated 1119 and later.
Added note to Table 7.6.
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NOTES:
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