C8051T605-GSR [SILICON]
暂无描述;
| 型号： | C8051T605-GSR |
| 厂家： | 
SILICON |
| 描述： | 暂无描述 可编程只读存储器 电动程控只读存储器 |
| 文件： | 总168页 (文件大小：1652K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
C8051T600/1/2/3/4/5
Mixed Signal OTP EPROM MCU Family
High Speed 8051 µC Core
Analog Peripherals
-
10-Bit Analog to Digital Converter
-
Pipe-lined instruction architecture; executes 70% of
instructions in 1 or 2 system clocks
•
•
•
Up to 500 ksps
Up to 8 external inputs
-
-
25 MIPS peak throughput with 25 MHz clock
Expanded interrupt handler
V
from external pin, V , or internal regulator
REF
DD
•
•
Built-in temperature sensor
External conversion start input option
Digital Peripherals
-
Comparator
-
8 port I/O; All 5 V tolerant with high sink current
•
•
•
Programmable hysteresis and response time
Configurable as interrupt or reset source
Low current (< 0.5 µA)
-
Hardware enhanced UART and SMBus™ serial
ports
Memory
-
-
Three general purpose 16-bit counter/timers
16-Bit programmable counter array (PCA) with three
capture/compare modules
-
256 bytes internal data RAM
-
8, 4 or 2 kB one time programmable code memory
On-Chip Debug
-
•
•
•
•
8 or 16-bit PWM
C8051F300 can be used as in-system code devel-
opment platform; complete development kit avail-
able
Rising / falling edge capture
Frequency output
Software timer
Clock Sources
-
On-chip debug circuitry facilitates full speed,
non-intrusive in-system debug
-
-
-
Internal oscillator: 24.5 MHz with ±2% accuracy
supports UART operation
External oscillator: RC, Single Capacitor, or CMOS
Clock Modes
Can switch between clock sources on-the-fly; useful
in power saving modes
Supply Voltage 1.8 to 3.6 V
-
-
-
-
On-chip LDO regulator for core supply
Typical operating current: 5.0 mA @ 25 MHz
Typical stop mode current (regulator off): <0.1 µA
Built-in brown-out detector
Temperature Range: –40 to +85 °C
11-Pin QFN or 14-Pin SOIC Package
-
QFN Size = 3 x 3 mm
ANALOG
DIGITAL I/O
PERIPHERALS
UART
SMBus
PCA
TEMP
SENSOR
A
M
U
X
10-bit
500 ksps
ADC
Timer 0
Timer 1
Timer 2
+
-
C8051T600/2/4
VOLTAGE
COMPARATOR
CALIBRATED PRECISION INTERNAL
OSCILLATOR
HIGH-SPEED CONTROLLER CORE
2/4/8 kB
OTP EPROM
12
8051 CPU
(25 MIPS)
DEBUG
256 B SRAM
POR WDT
INTERRUPTS
CIRCUITRY
Rev. 0.5 2/07
Copyright © 2007 by Silicon Laboratories
C8051T60x
This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
C8051T600/1/2/3/4/5
2
Rev. 0.5
C8051T600/1/2/3/4/5
Table of Contents
1. System Overview.................................................................................................... 13
1.1. CIP-51™ Microcontroller Core.......................................................................... 16
1.1.1. Fully 8051 Compatible.............................................................................. 16
1.1.2. Improved Throughput............................................................................... 16
1.1.3. Additional Features .................................................................................. 17
1.2. On-Chip Memory............................................................................................... 18
1.3. On-Chip Debug Circuitry and Code Development Options............................... 18
1.4. Programmable Digital I/O and Crossbar........................................................... 19
1.5. Serial Ports ....................................................................................................... 19
1.6. Programmable Counter Array........................................................................... 19
1.7. 10-Bit Analog to Digital Converter (C8051T600/2/4) ........................................ 21
1.8. Comparator....................................................................................................... 22
2. Absolute Maximum Ratings .................................................................................. 23
3. Global Electrical Characteristics .......................................................................... 24
4. Pinout and Package Definitions............................................................................ 26
5. ADC0 - 10-Bit SAR ADC (C8051T600/2/4 Only).................................................... 31
5.1. Analog Multiplexer ............................................................................................ 32
5.2. Gain Setting ...................................................................................................... 32
5.3. Output Coding................................................................................................... 32
5.4. 8-Bit Compatibility Mode................................................................................... 32
5.5. Temperature Sensor......................................................................................... 33
5.5.1. Calibration ................................................................................................ 33
5.6. Modes of Operation .......................................................................................... 36
5.6.1. Starting a Conversion............................................................................... 36
5.6.2. Tracking Modes........................................................................................ 37
5.6.3. Settling Time Requirements..................................................................... 38
5.7. Programmable Window Detector...................................................................... 42
5.7.1. Window Detector Example....................................................................... 42
6. Voltage Reference Options.................................................................................... 45
7. Comparator0 ........................................................................................................... 47
8. Voltage Regulator (REG0)...................................................................................... 53
9. CIP-51 Microcontroller ........................................................................................... 55
9.1. Instruction Set................................................................................................... 56
9.1.1. Instruction and CPU Timing ..................................................................... 56
9.2. Memory Organization........................................................................................ 61
9.2.1. Program Memory...................................................................................... 61
9.2.2. Data Memory............................................................................................ 62
9.2.3. General Purpose Registers...................................................................... 62
9.2.4. Bit Addressable Locations........................................................................ 63
9.2.5. Stack ....................................................................................................... 63
9.2.6. Special Function Registers....................................................................... 63
9.2.7. Register Descriptions ............................................................................... 67
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3
C8051T600/1/2/3/4/5
9.3. Interrupt Handler............................................................................................... 70
9.3.1. MCU Interrupt Sources and Vectors ........................................................ 71
9.3.2. External Interrupts.................................................................................... 71
9.3.3. Interrupt Priorities..................................................................................... 71
9.3.4. Interrupt Latency ...................................................................................... 72
9.3.5. Interrupt Register Descriptions................................................................. 73
9.4. Power Management Modes.............................................................................. 78
9.4.1. Idle Mode.................................................................................................. 78
9.4.2. Stop Mode................................................................................................ 79
10.Reset Sources......................................................................................................... 81
10.1.Power-On Reset............................................................................................... 82
10.2.Power-Fail Reset/V Monitor ......................................................................... 83
DD
10.3.External Reset.................................................................................................. 83
10.4.Missing Clock Detector Reset .......................................................................... 83
10.5.Comparator0 Reset .......................................................................................... 83
10.6.PCA Watchdog Timer Reset ............................................................................ 83
10.7.OTP Error Reset............................................................................................... 84
10.8.Software Reset................................................................................................. 84
11.One-Time Programmable Read-Only Memory..................................................... 87
11.1.Programming the EPROM Memory.................................................................. 87
11.2.Security Options ............................................................................................... 88
11.3.Program Memory CRC..................................................................................... 89
11.3.1.Performing 32-bit CRCs on Full EPROM Content ................................... 89
11.3.2.Performing 16-bit CRCs on 256-Byte EPROM Blocks............................. 89
12.Oscillators............................................................................................................... 91
12.1.Calibrated Internal Oscillator ............................................................................ 91
12.2.External Oscillator Circuit ................................................................................. 93
12.3.System Clock Selection.................................................................................... 93
12.4.External Capacitor Example............................................................................. 95
12.5.External RC Example ....................................................................................... 95
13.Port Input/Output.................................................................................................... 97
13.1.Priority Crossbar Decoder ................................................................................ 98
13.2.Port I/O Initialization ......................................................................................... 99
13.3.General Purpose Port I/O............................................................................... 102
14.SMBus ................................................................................................................... 105
14.1.Supporting Documents................................................................................... 106
14.2.SMBus Configuration...................................................................................... 106
14.3.SMBus Operation ........................................................................................... 106
14.3.1.Arbitration............................................................................................... 107
14.3.2.Clock Low Extension.............................................................................. 108
14.3.3.SCL Low Timeout................................................................................... 108
14.3.4.SCL High (SMBus Free) Timeout .......................................................... 108
14.4.Using the SMBus............................................................................................ 108
14.4.1.SMBus Configuration Register............................................................... 110
14.4.2.SMB0CN Control Register..................................................................... 113
4
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C8051T600/1/2/3/4/5
14.4.3.Data Register ......................................................................................... 116
14.5.SMBus Transfer Modes.................................................................................. 117
14.5.1.Master Transmitter Mode....................................................................... 117
14.5.2.Master Receiver Mode........................................................................... 118
14.5.3.Slave Receiver Mode............................................................................. 119
14.5.4.Slave Transmitter Mode......................................................................... 120
14.6.SMBus Status Decoding................................................................................. 120
15.UART0.................................................................................................................... 123
15.1.Enhanced Baud Rate Generation................................................................... 124
15.2.Operational Modes ......................................................................................... 125
15.2.1.8-Bit UART............................................................................................. 125
15.2.2.9-Bit UART............................................................................................. 126
15.3.Multiprocessor Communications .................................................................... 126
16.Timers.................................................................................................................... 131
16.1.Timer 0 and Timer 1 ....................................................................................... 131
16.1.1.Mode 0: 13-bit Counter/Timer................................................................ 131
16.1.2.Mode 1: 16-bit Counter/Timer................................................................ 133
16.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 133
16.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 134
16.2.Timer 2 .......................................................................................................... 139
16.2.1.16-bit Timer with Auto-Reload................................................................ 139
16.2.2.8-bit Timers with Auto-Reload................................................................ 140
17.Programmable Counter Array ............................................................................. 143
17.1.PCA Counter/Timer ........................................................................................ 144
17.2.Capture/Compare Modules ............................................................................ 145
17.2.1.Edge-triggered Capture Mode................................................................ 146
17.2.2.Software Timer (Compare) Mode........................................................... 147
17.2.3.High Speed Output Mode....................................................................... 148
17.2.4.Frequency Output Mode ........................................................................ 149
17.2.5.8-Bit Pulse Width Modulator Mode......................................................... 150
17.2.6.16-Bit Pulse Width Modulator Mode....................................................... 151
17.3.Watchdog Timer Mode ................................................................................... 151
17.3.1.Watchdog Timer Operation.................................................................... 152
17.3.2.Watchdog Timer Usage ......................................................................... 153
17.4.Register Descriptions for PCA........................................................................ 154
18.Revision Specific Behavior ................................................................................. 159
18.1.Revision Identification..................................................................................... 159
18.2.SAR Clock Maximum...................................................................................... 160
18.3.V Monitor Oscillation .................................................................................. 160
DD
19.C2 Interface........................................................................................................... 161
19.1.C2 Interface Registers.................................................................................... 161
19.2.C2 Pin Sharing ............................................................................................... 166
Contact Information.................................................................................................. 168
Rev. 0.5
5
C8051T600/1/2/3/4/5
NOTES:
6
Rev. 0.5
C8051T600/1/2/3/4/5
List of Figures
1. System Overview
Figure 1.1. C8051T600/2/4 Block Diagram.............................................................. 15
Figure 1.2. C8051T601/3/5 Block Diagram.............................................................. 15
Figure 1.3. On-Chip Clock and Reset ...................................................................... 17
Figure 1.4. On-chip Memory Map (C8051T600/1 shown)........................................ 18
Figure 1.5. Digital Crossbar Diagram....................................................................... 19
Figure 1.6. PCA Block Diagram ............................................................................... 20
Figure 1.7. PCA Block Diagram ............................................................................... 20
Figure 1.8. 10-Bit ADC Block Diagram..................................................................... 21
Figure 1.9. Comparator Block Diagram.................................................................... 22
2. Absolute Maximum Ratings
3. Global Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. QFN-11 Pinout Diagram (Top View) ...................................................... 27
Figure 4.2. QFN-11 Package Drawing ..................................................................... 28
Figure 4.3. SOIC-14 Pinout Diagram (Top View)..................................................... 29
Figure 4.4. SOIC-14 Package Drawing.................................................................... 30
5. ADC0 - 10-Bit SAR ADC (C8051T600/2/4 Only)
Figure 5.1. ADC0 Functional Block Diagram............................................................ 31
Figure 5.2. Temperature Sensor Transfer Function................................................. 33
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (V
= 2.4 V) ....... 34
REF
Figure 5.4. ADC Tracking and Conversion Timing................................................... 37
Figure 5.5. ADC0 Equivalent Input Circuits.............................................................. 38
Figure 5.6. ADC Window Compare Examples ......................................................... 42
6. Voltage Reference Options
Figure 6.1. Voltage Reference Functional Block Diagram ....................................... 45
7. Comparator0
Figure 7.1. Comparator0 Functional Block Diagram ................................................ 47
Figure 7.2. Comparator Hysteresis Plot ................................................................... 48
8. Voltage Regulator (REG0)
9. CIP-51 Microcontroller
Figure 9.1. CIP-51 Block Diagram............................................................................ 55
Figure 9.2. Program Memory Maps.......................................................................... 61
Figure 9.3. Data Memory Map.................................................................................. 62
10.Reset Sources
Figure 10.1. Reset Sources...................................................................................... 81
Figure 10.2. Power-On and V Monitor Reset Timing ........................................... 82
DD
11.One-Time Programmable Read-Only Memory
Figure 11.1. OTP EPROM Program Memory Map................................................... 88
12.Oscillators
Figure 12.1. Oscillator Diagram................................................................................ 91
13.Port Input/Output
Figure 13.1. Port I/O Functional Block Diagram....................................................... 97
Rev. 0.5
7
C8051T600/1/2/3/4/5
Figure 13.2. Port I/O Cell Block Diagram ................................................................. 97
Figure 13.3. Crossbar Priority Decoder with XBR0 = 0x00 ...................................... 98
Figure 13.4. Crossbar Priority Decoder with XBR0 = 0x44 ...................................... 99
14.SMBus
Figure 14.1. SMBus Block Diagram ....................................................................... 105
Figure 14.2. Typical SMBus Configuration............................................................. 106
Figure 14.3. SMBus Transaction............................................................................ 107
Figure 14.4. Typical SMBus SCL Generation......................................................... 111
Figure 14.5. Typical Master Transmitter Sequence................................................ 117
Figure 14.6. Typical Master Receiver Sequence.................................................... 118
Figure 14.7. Typical Slave Receiver Sequence...................................................... 119
Figure 14.8. Typical Slave Transmitter Sequence.................................................. 120
15.UART0
Figure 15.1. UART0 Block Diagram ....................................................................... 123
Figure 15.2. UART0 Baud Rate Logic.................................................................... 124
Figure 15.3. UART Interconnect Diagram .............................................................. 125
Figure 15.4. 8-Bit UART Timing Diagram............................................................... 125
Figure 15.5. 9-Bit UART Timing Diagram............................................................... 126
Figure 15.6. UART Multi-Processor Mode Interconnect Diagram .......................... 127
16.Timers
Figure 16.1. T0 Mode 0 Block Diagram.................................................................. 132
Figure 16.2. T0 Mode 2 Block Diagram.................................................................. 133
Figure 16.3. T0 Mode 3 Block Diagram.................................................................. 134
Figure 16.4. Timer 2 16-Bit Mode Block Diagram .................................................. 139
Figure 16.5. Timer 2 8-Bit Mode Block Diagram .................................................... 140
17.Programmable Counter Array
Figure 17.1. PCA Block Diagram............................................................................ 143
Figure 17.2. PCA Counter/Timer Block Diagram.................................................... 144
Figure 17.3. PCA Interrupt Block Diagram ............................................................. 145
Figure 17.4. PCA Capture Mode Diagram.............................................................. 146
Figure 17.5. PCA Software Timer Mode Diagram.................................................. 147
Figure 17.6. PCA High Speed Output Mode Diagram............................................ 148
Figure 17.7. PCA Frequency Output Mode ............................................................ 149
Figure 17.8. PCA 8-Bit PWM Mode Diagram ......................................................... 150
Figure 17.9. PCA 16-Bit PWM Mode...................................................................... 151
Figure 17.10. PCA Module 2 with Watchdog Timer Enabled ................................. 152
18.Revision Specific Behavior
Figure 18.1. Device Package - SOIC 14 ................................................................ 159
Figure 18.2. Device Package - QFN 10.................................................................. 159
19.C2 Interface
Figure 19.1. Typical C2 Pin Sharing....................................................................... 166
8
Rev. 0.5
C8051T600/1/2/3/4/5
List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 14
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings .................................................................... 23
3. Global Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics ....................................................... 24
Table 3.2. Index to Electrical Characteristics Tables ............................................... 25
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051T600/1/2/3/4/5 ........................................... 26
Table 4.2. QFN-11 Package Dimensions ................................................................ 28
Table 4.3. SOIC-14 Package Dimensions ............................................................... 30
5. ADC0 - 10-Bit SAR ADC (C8051T600/2/4 Only)
Table 5.1. ADC0 Electrical Characteristics .............................................................. 44
6. Voltage Reference Options
Table 6.1. External Voltage Reference Circuit Electrical Characteristics ................ 46
7. Comparator0
Table 7.1. Comparator0 Electrical Characteristics .................................................. 52
8. Voltage Regulator (REG0)
Table 8.1. Internal Voltage Regulator Electrical Characteristics ............................. 54
9. CIP-51 Microcontroller
Table 9.1. CIP-51 Instruction Set Summary ............................................................ 57
Table 9.2. Special Function Register (SFR) Memory Map ...................................... 64
Table 9.3. Special Function Registers ..................................................................... 65
Table 9.4. Interrupt Summary .................................................................................. 72
10.Reset Sources
Table 10.1. User Code Space Address Limits ......................................................... 84
Table 10.2. Reset Electrical Characteristics ............................................................ 86
11.One-Time Programmable Read-Only Memory
Table 11.1. EPROM Electrical Characteristics ........................................................ 87
Table 11.2. Security Byte Decoding ........................................................................ 88
12.Oscillators
Table 12.1. Internal Oscillator Electrical Characteristics ......................................... 92
13.Port Input/Output
Table 13.1. Port I/O DC Electrical Characteristics ................................................. 104
14.SMBus
Table 14.1. SMBus Clock Source Selection .......................................................... 110
Table 14.2. Minimum SDA Setup and Hold Times ................................................ 111
Table 14.3. Sources for Hardware Changes to SMB0CN ..................................... 115
Table 14.4. SMBus Status Decoding ..................................................................... 121
15.UART0
Table 15.1. Timer Settings for Standard Baud Rates Using
the Internal 24.5 MHz Oscillator ......................................................... 130
Rev. 0.5
9
C8051T600/1/2/3/4/5
16.Timers
17.Programmable Counter Array
Table 17.1. PCA Timebase Input Options ............................................................. 144
Table 17.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 145
Table 17.3. Watchdog Timer Timeout Intervals ..................................................... 153
18.Revision Specific Behavior
19.C2 Interface
10
Rev. 0.5
C8051T600/1/2/3/4/5
List of Registers
SFR Definition 5.1. TOFFH: Temperature Offset Measurement High Byte . . . . . . . . . 34
SFR Definition 5.2. TOFFL: Temperature Offset Measurement Low Byte . . . . . . . . . . 35
SFR Definition 5.3. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . 39
SFR Definition 5.4. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
SFR Definition 5.5. ADC0H: ADC0 Data Word High Byte . . . . . . . . . . . . . . . . . . . . . . 40
SFR Definition 5.6. ADC0L: ADC0 Data Word Low Byte . . . . . . . . . . . . . . . . . . . . . . . 40
SFR Definition 5.7. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
SFR Definition 5.8. ADC0GTH: ADC0 Greater-Than High Byte . . . . . . . . . . . . . . . . . . 43
SFR Definition 5.9. ADC0GTL: ADC0 Greater-Than Low Byte . . . . . . . . . . . . . . . . . . 43
SFR Definition 5.10. ADC0LTH: ADC0 Less-Than High Byte . . . . . . . . . . . . . . . . . . . 43
SFR Definition 5.11. ADC0LTL: ADC0 Less-Than Low Byte . . . . . . . . . . . . . . . . . . . . 43
SFR Definition 6.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
SFR Definition 7.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 51
SFR Definition 8.1. REG0CN: Voltage Regulator Control . . . . . . . . . . . . . . . . . . . . . . 54
SFR Definition 9.1. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
SFR Definition 9.2. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
SFR Definition 9.3. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
SFR Definition 9.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
SFR Definition 9.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
SFR Definition 9.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
SFR Definition 9.7. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 9.8. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
SFR Definition 9.9. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . . 75
SFR Definition 9.10. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . . 76
SFR Definition 9.11. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . 77
SFR Definition 9.12. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
SFR Definition 10.1. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
SFR Definition 12.1. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 12.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 12.3. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . . 94
SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 100
SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 101
SFR Definition 13.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 13.4. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
SFR Definition 13.5. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
SFR Definition 13.6. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 103
SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 112
SFR Definition 14.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
SFR Definition 14.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 15.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 128
SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 129
Rev. 0.5
11
C8051T600/1/2/3/4/5
SFR Definition 16.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
SFR Definition 16.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
SFR Definition 16.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 16.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 16.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 16.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 16.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 16.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
SFR Definition 16.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 142
SFR Definition 16.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 142
SFR Definition 16.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 16.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 17.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 17.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 17.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 156
SFR Definition 17.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 157
SFR Definition 17.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 157
SFR Definition 17.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 158
SFR Definition 17.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 158
C2 Register Definition 19.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
C2 Register Definition 19.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 162
C2 Register Definition 19.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 162
C2 Register Definition 19.4. DEVCTL: C2 Device State . . . . . . . . . . . . . . . . . . . . . . . 162
C2 Register Definition 19.5. EPCTL: C2 EPROM Programming Control . . . . . . . . . . 162
C2 Register Definition 19.6. EPDAT: C2 EPROM Data . . . . . . . . . . . . . . . . . . . . . . . 163
C2 Register Definition 19.7. EPADDRH: C2 EPROM Address High Byte . . . . . . . . . 163
C2 Register Definition 19.8. EPADDRL: C2 EPROM Address Low Byte . . . . . . . . . . 163
C2 Register Definition 19.9. CRC0: CRC Byte 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
C2 Register Definition 19.10. CRC1: CRC Byte 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
C2 Register Definition 19.11. CRC2: CRC Byte 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
C2 Register Definition 19.12. CRC3: CRC Byte 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
12
Rev. 0.5
C8051T600/1/2/3/4/5
1. System Overview
C8051T600/1/2/3/4/5 devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted fea-
tures are listed below. Refer to Table 1.1 on page 14 for specific product feature selection.
•
•
•
•
•
•
•
High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS)
In-system, full-speed, non-intrusive debug interface
C8051F300 ISP Flash device is available for quick in-system code development
10-bit 500 ksps ADC with programmable analog multiplexer and integrated temperature sensor
Precision calibrated 24.5 MHz internal oscillator
2/4/8 kB of on-chip One-Time Programmable (OTP) EPROM
256 bytes of on-chip RAM
2
•
•
•
SMBus/I C and Enhanced UART serial interfaces implemented in hardware
Three general-purpose 16-bit timers
Programmable Counter/Timer Array (PCA) with three capture/compare modules and Watchdog Timer
function
•
•
•
On-chip Power-On Reset and Supply Monitor
On-chip Voltage Comparator
Byte-wide I/O Port (5 V tolerant)
With on-chip Power-On Reset, Supply Monitor, Watchdog Timer, and clock oscillator, the C8051T600/1/2/
3/4/5 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 C8051T600/1/2/3/4/5 family of processors will run on the C8051F300 Mixed-signal
ISP Flash microcontroller, providing a quick, cost-effective way to develop code without requiring special
emulator circuitry. The C8051T600/1/2/3/4/5 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, run
and halt commands. All analog and digital peripherals are fully functional while debugging using C2. The
two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying
package pins.
Each device is specified for 1.8-to-3.6 V operation over the industrial temperature range (–45 to +85 °C).
An internal LDO is used to supply the processor core voltage at 1.8 V. The Port I/O and RST pins are toler-
ant of input signals up to 5 V. The C8051T600/1/2/3/4/5 are available in 3 x 3 mm 11-pin QFN or 14-pin
SOIC packaging.
Rev. 0.5
13
C8051T600/1/2/3/4/5
Table 1.1. Product Selection Guide
C8051T600-GM
C8051T600-GS
C8051T601-GM
C8051T601-GS
C8051T602-GM
C8051T602-GS
C8051T603-GM
C8051T603-GS
C8051T604-GM
C8051T604-GS
C8051T605-GM
C8051T605-GS
25
25
25
25
25
25
25
25
25
25
25
25
8k*
8k*
8k*
8k*
4k
256
256
256
256
256
256
256
256
256
256
256
256
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
8
8
8
8
8
8
8
8
8
8
8
8
3
3
—
—
3
3
—
—
3
3
-
3
3
—
—
3
3
—
—
3
3
-
1
1
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
3
3
3
3
3
3
3
QFN-11
SOIC-14
QFN-11
SOIC-14
QFN-11
SOIC-14
QFN-11
SOIC-14
QFN-11
SOIC-14
QFN-11
SOIC-14
4k
4k
4k
2k
2k
2k
2k
-
-
*512 Bytes Reserved for Factory Use
14
Rev. 0.5
C8051T600/1/2/3/4/5
Port I/O Configuration
CIP-51 8051
Controller Core
Digital Peripherals
P0.0/VREF
P0.1
UART
2k/4k/8k Byte OTP
Program Memory
Power On
Reset
Timers 0,
1, and 2
P0.2/VPP
P0.3/EXTCLK
P0.4/TX
P0.5/RX
P0.6
Priority
Crossbar
Decoder
Reset
Port 0
Drivers
PCA/
WDT
Debug /
Programming
Hardware
C2CK/RST
256 byte SRAM
SYSCLK
SFR
Bus
SMBus
P0.7/C2D
C2D
Crossbar Control
Power Net
Analog Peripherals
VDD
GND
CP0
+
-
VDD
VREF
External
Clock
Circuit
Precision
Internal
Oscillator
Comparator
VDD
EXTCLK
A
AIN0 - AIN7
10-bit
500ksps
ADC
M
U
X
System Clock
Configuration
Temp
Sensor
Figure 1.1. C8051T600/2/4 Block Diagram
Port I/O Configuration
CIP-51 8051
Controller Core
Digital Peripherals
P0.0
UART
2k/4k/8k Byte OTP
Program Memory
Power On
Reset
P0.1
Timers 0,
P0.2/VPP
P0.3/EXTCLK
P0.4/TX
P0.5/RX
P0.6
1, and 2
Priority
Crossbar
Decoder
Reset
Port 0
Drivers
PCA/
WDT
Debug /
Programming
Hardware
C2CK/RST
256 byte SRAM
SYSCLK
SFR
Bus
SMBus
P0.7/C2D
C2D
Crossbar Control
Power Net
VDD
GND
Analog Peripherals
External
Clock
Circuit
Precision
Internal
Oscillator
CP0
+
EXTCLK
-
Comparator
System Clock
Configuration
Figure 1.2. C8051T601/3/5 Block Diagram
Rev. 0.5
15
C8051T600/1/2/3/4/5
1.1. CIP-51™ Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051T600/1/2/3/4/5 family utilizes Silicon Labs' proprietary CIP-51 microcontroller core. The CIP-51
is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can
be used to develop software. The CIP-51 core offers all the peripherals included with a standard 8052,
including two standard 16-bit counter/timers, one enhanced 16-bit counter/timer with external clock input, a
full-duplex UART with extended baud rate configuration, 256 bytes of internal RAM, 128 byte Special
Function Register (SFR) address space, and a byte-wide I/O Port.
1.1.2. Improved Throughput
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 with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core exe-
cutes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than
four system clock cycles. With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of
25 MIPS.
The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that
require each execution time.
Clocks to Execute
Number of Instructions
1
26
2
50
2/3
5
3
14
3/4
7
4
3
4/5
1
5
2
8
1
16
Rev. 0.5
C8051T600/1/2/3/4/5
1.1.3. Additional Features
The C8051T600/1/2/3/4/5 SoC family includes several key enhancements to the CIP-51 core and peripher-
als to improve performance and ease of use in end applications.
The extended interrupt handler provides 12 interrupt sources into the CIP-51, allowing numerous analog
and digital peripherals to interrupt the controller. An interrupt driven system requires less intervention by
the MCU, giving it more effective throughput. The extra interrupt sources are very useful when building
multi-tasking, real-time systems.
Several reset sources are available: power-on reset circuitry (POR), a Supply Monitor, a Watchdog Timer,
a Missing Clock Detector, a voltage level detection from Comparator0, a forced software reset, an external
reset pin, and an illegal OTP read/write detection. Each reset source except for the POR, Reset Input Pin,
and OTP protection may be disabled by the user in software. The WDT may be permanently enabled in
software after a power-on reset during MCU initialization.
The internal oscillator is factory calibrated to 24.5 MHz, and is accurate to ±2% over the entire operating
supply and temperature range. The internal oscillator can be directly divided by factors of 2, 4, or 8 to pro-
vide slower internal clock options. An external oscillator input is also included, allowing an external CMOS
clock, external capacitor, or external RC circuit to generate the system clock. If desired, the system clock
source may be switched on-the-fly to the external oscillator circuit. An external oscillator can be extremely
useful in low power applications, allowing the MCU to run from a slower (power saving) external clock
source, while periodically switching to the internal oscillator when faster operation is required.
Supply
Monitor
'0'
/RST
Power On
Reset
Comparator 0
(wired-OR)
P0.x
P0.y
+
-
C0RSEF
Missing
Clock
Detector
(one-
shot)
Reset
Funnel
PCA
WDT
(Software Reset)
SWRSF
EN
Illegal OTP
operation
EN
Internal
Oscillator
System
Clock
External
Clock
CIP-51
Microcontroller
Core
EXTCLK
System Reset
Clock Select
Source
Extended Interrupt
Handler
Figure 1.3. On-Chip Clock and Reset
Rev. 0.5
17
C8051T600/1/2/3/4/5
1.2. On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data
RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
The C8051T600/1 include 8 kB of EPROM program memory, the C8051T602/3 include 4 kB, and the
C8051T604/5 include 2 kB. See Figure 1.4 for the C8051T600/1 system memory map.
PROGRAM MEMORY
DATA MEMORY
INTERNAL DATA ADDRESS SPACE
0xFF
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Register's
(Direct Addressing Only)
RESERVED
0x1E00
0x1DFF
0x80
0x7F
(Direct and Indirect
Addressing)
Lower 128 RAM
(Direct and Indirect
Addressing)
8k bytes
OTP Memory
0x30
0x2F
Bit Addressable
0x20
0x1F
General Purpose
Registers
0x00
0x0000
Figure 1.4. On-chip Memory Map (C8051T600/1 shown)
1.3. On-Chip Debug Circuitry and Code Development Options
The C8051T600/1/2/3/4/5 devices include on-chip Silicon Labs 2-Wire (C2) debug circuitry that provides
non-intrusive, full speed, in-circuit debugging of the production part installed in the end application.
Silicon Labs' debugging system supports inspection and modification of memory and registers, break-
points, and single stepping. No additional target RAM, program memory, timers, or communications chan-
nels are required. All the digital and analog peripherals are functional and work correctly while debugging.
All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single
stepping, or at a breakpoint in order to keep them synchronized.
The C8051F300 MCU can be used to quickly develop code for a system using a device in the C8051T600/
1/2/3/4/5 family. The C8051F300 is an In-System Programmable, Flash-based device that uses the same
pinout as the C8051T600/1/2/3/4/5 devices, and can run code written for the C8051T600/1/2/3/4/5. The
C8051T600DK development kit provides all the hardware and software necessary to develop application
code and perform in-circuit debugging for the C8051T600/1/2/3/4/5 MCUs. The kit includes software with a
developer's studio and debugger, an assembler/linker and evaluation ‘C’ compiler, and the necessary
cables for connection to the target board or the end-system. The development kit includes an SOIC Socket
Daughter Card for programming SOIC devices, samples of the C8051T600-GS, and a C8051F300 Emula-
tion Daughter Card for rapid code development. An AC to DC wall adapter is supplied for powering the
board.
18
Rev. 0.5
C8051T600/1/2/3/4/5
1.4. Programmable Digital I/O and Crossbar
C8051T600/1/2/3/4/5 devices include a byte-wide I/O Port that behaves like a typical 8051 Port with a few
enhancements. Each Port pin may be configured as an analog input or a digital I/O pin. Pins selected as
digital I/Os may additionally be configured for push-pull or open-drain output. The “weak pullups” that are
fixed on typical 8051 devices may be globally disabled, providing additional power savings.
Perhaps the most unique Port I/O enhancement is the Digital Crossbar. This is a digital switching network
that allows mapping of internal digital system resources to Port I/O pins (See Figure 1.5). On-chip counter/
timers, serial buses, HW interrupts, comparator output, and other digital signals in the controller can be
configured to appear on the Port I/O pins using the Crossbar Control registers. This allows the user to
select the exact mix of general purpose Port I/O and digital resources needed for the application.
XBR0, XBR1,
P0MDOUT,
XBR2 Registers
P0MDIN Registers
Priority
Decoder
2
2
2
Highest
Priority
UART
Digital
Crossbar
SMBus
CP0
Outputs
P0.0
P0.7
P0
I/O
Cells
8
SYSCLK
4
2
PCA
T0, T1
8
Lowest
Priority
Port Latch
P0
(P0.0-P0.7)
Figure 1.5. Digital Crossbar Diagram
1.5. Serial Ports
2
The C8051T600/1/2/3/4/5 Family includes an SMBus/I C interface and a full-duplex UART with enhanced
baud rate configuration. Each of the serial buses is fully implemented in hardware and makes extensive
use of the CIP-51's interrupts, thus requiring very little CPU intervention. Both serial buses can be used at
the same time.
1.6. Programmable Counter Array
An on-chip Programmable Counter/Timer Array (PCA) is included in addition to the three 16-bit general
purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with three pro-
grammable capture/compare modules. The PCA clock is derived from one of six sources: the system clock
divided by 12, the system clock divided by 4, Timer 0 overflows, an External Clock Input (ECI), the system
clock, or the external oscillator clock source divided by 8. The external clock source selection is useful for
Rev. 0.5
19
C8051T600/1/2/3/4/5
real-time clock functionality, where the PCA is clocked by an external source while the internal oscillator
drives the system clock.
Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture,
Software Timer, High Speed Output, 8- or 16-bit Pulse Width Modulator, or Frequency Output. Additionally,
Capture/Compare Module 2 offers watchdog timer (WDT) capabilities. Following a system reset, Module 2
is configured and enabled in WDT mode. The PCA Capture/Compare Module I/O and External Clock Input
may be routed to Port I/O via the Digital Crossbar.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
PCA
16-Bit Counter/Timer
CLOCK
MUX
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Digital Crossbar
Port I/O
Figure 1.7. PCA Block Diagram
20
Rev. 0.5
C8051T600/1/2/3/4/5
1.7. 10-Bit Analog to Digital Converter (C8051T600/2/4)
The C8051T600/2/4 include an on-chip 10-bit SAR ADC with a 10-channel input multiplexer. With a maxi-
mum throughput of 500 ksps, the ADC offers true 10-bit accuracy with an INL of ±1LSB. The ADC system
includes a configurable analog multiplexer that selects the ADC input, and gain settings of 1x or 0.5x. Each
Port pin is available as an ADC input; additionally, the on-chip Temperature Sensor output and the power
supply voltage (V ) are available as ADC inputs. User firmware may shut down the ADC when it is not in
DD
use to save power.
Conversions can be started in five ways: a software command, an overflow of Timer 0, 1, or 2, or an exter-
nal convert start signal. This flexibility allows the start of conversion to be triggered by software events, a
periodic signal (timer overflows), or external HW signals. Conversion completions are indicated by a status
bit and an interrupt (if enabled). The resulting 10-bit data word is latched into two SFRs upon completion of
a conversion.
An 8-bit compatibility mode is included in the device to facilitate development and backwards-compatibility
with the C8051F300.
Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is
either within or outside of a specified range. The ADC can monitor a key voltage continuously in back-
ground mode, but not interrupt the controller unless the converted data is within or outside of the specified
range.
Configuration and Control Registers
Software Write
T0 Overflow
Start
Conversion
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
TMR2 Overflow
T1 Overflow
External
Convert Start
10 bit
SAR
ADC
X1 or
X0.5
10-to-1
AMUX
ADC Data
Registers
10
Temp
Sensor
Window
Compare
Interrupt
Window Compare
Logic
VDD
End of
Conversion
Interrupt
Figure 1.8. 10-Bit ADC Block Diagram
Rev. 0.5
21
C8051T600/1/2/3/4/5
1.8. Comparator
C8051T600/1/2/3/4/5 devices include an on-chip voltage comparator that is enabled/disabled and config-
ured via user software. All Port I/O pins may be configured as comparator inputs. Two comparator outputs
may be routed to a Port pin if desired: a latched output and/or an unlatched (asynchronous) output. Com-
parator response time is programmable, allowing the user to select between high-speed and low-power
modes. Positive and negative hysteresis is also configurable.
Comparator interrupts may be generated on rising, falling, or both edges. When in IDLE mode, these inter-
rupts may be used as a “wake-up” source. The comparator may also be configured as a reset source.
P0.0
P0.2
P0.4
P0.6
CP0 +
Interrupt
Handler
VDD
GND
+
-
SET
CLR
SET
CLR
D
Q
Q
D
Q
Q
Crossbar
P0.1
P0.3
P0.5
P0.7
(SYNCHRONIZER)
CP0 -
Reset
Decision
Tree
Figure 1.9. Comparator Block Diagram
22
Rev. 0.5
C8051T600/1/2/3/4/5
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter
Conditions
Min
–55
–65
Typ
—
Max
125
150
5.8
Units
°C
Ambient temperature under bias
Storage Temperature
—
°C
Voltage on RST or any Port I/O Pin
(except V during programming) with
V
V
> 2.2 V
< 2.2 V
–0.3
–0.3
—
—
V
V
DD
DD
V
+ 3.6
PP
DD
respect to GND
Voltage on V with respect to GND
V
V
> 2.4 V
–0.3
—
7.0
10
V
s
PP
DD
PP
during a programming operation
Duration of High-voltage on V pin
> (V + 3.6 V)
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
100
mA
DD
Maximum output current sunk by RST
or any Port pin
—
—
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. 0.5
23
C8051T600/1/2/3/4/5
3. Global Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
1
Regulator in Normal Mode
Regulator in Bypass Mode
1.8
1.7
3.0
1.8
3.6
1.9
V
V
Supply Voltage
Digital Supply Current with CPU Active V = 1.8 V, Clock = 25 MHz
—
—
4.3
TBD
5.0
—
—
mA
mA
mA
mA
DD
2
V
V
= 1.8 V, Clock = 1 MHz
= 3.0 V, Clock = 25 MHz
DD
DD
TBD
2
V
= 3.0 V, Clock = 1 MHz
DD
2
2
Digital Supply Current with CPU Inac-
tive (not accessing EPROM)
TBD
TBD
TBD
TBD
mA
mA
mA
mA
V
V
V
V
= 1.8 V, Clock = 25 MHz
DD
DD
DD
DD
2
= 1.8 V, Clock = 1 MHz
= 3.0 V, Clock = 25 MHz
2
= 3.0 V, Clock = 1 MHz
Digital Supply Current (shutdown)
Oscillator not running,
Internal Regulator Off
—
—
TBD
TBD
—
—
—
µA
V
Digital Supply RAM Data Retention
Voltage
Specified Operating Temperature
Range
–40
+85
°C
3
0
—
—
25
60
MHz
%
SYSCLK (system clock frequency)
SYSCLK Duty Cycle
40
Notes:
1. Analog performance is degraded when VDD is below 1.8 V.
2. Specifications below 2 MHz or with CPU Inactive assume memory power controller is enabled.
3. SYSCLK must be at least 32 kHz to enable debugging.
Other electrical characteristics tables are found in the data sheet section corresponding to the associated
peripherals. For more information on electrical characteristics for a specific peripheral, refer to the page
indicated in Table 3.2.
24
Rev. 0.5
C8051T600/1/2/3/4/5
Table 3.2. Index to Electrical Characteristics Tables
Table Title
Page
No.
ADC0 Electrical Characteristics
44
46
External Voltage Reference Circuit Electrical Characteristics
Comparator0 Electrical Characteristics
Reset Electrical Characteristics
52
86
EPROM Electrical Characteristics
87
Internal Oscillator Electrical Characteristics
Port I/O DC Electrical Characteristics
92
104
Rev. 0.5
25
C8051T600/1/2/3/4/5
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051T600/1/2/3/4/5
Pin Number Pin Number
Name
Type
Description
QFN-11
SOIC-14
1
5
VREF / A In
External Voltage Reference Input.
P0.0
P0.1
D I/O or A In Port 0.0. See Section 13 for complete description.
D I/O or A In Port 0.1. See Section 13 for complete description.
Power Supply Voltage.
2
3
6
7
V
DD
4
8
V
/
A In
V
Programming Supply Voltage
PP
PP
D I/O or A In
P0.2
Port 0.2. See Section 13 for complete description.
5
10
EXTCLK/ D I/O or A I/O This pin can be used as the external clock input for
CMOS, RC, or Capacitor configurations. See Sec-
tion 12.2.
P0.3
P0.4
P0.5
D I/O or A In Port 0.3. See Section 13 for complete description.
D I/O or A In Port 0.4. See Section 13 for complete description.
D I/O or A In Port 0.5. See Section 13 for complete description.
6
7
8
12
13
14
C2CK / D I/O
Clock signal for the C2 Development Interface.
RST
D I/O
Device Reset. Open-drain output of internal POR
or V monitor. An external source can initiate a
DD
system reset by driving this pin low for at least 10
µs.
9
1
2
P0.6
D I/O or A In Port 0.6. See Section 13 for complete description.
Data signal for the C2 Development Interface.
10
C2D / D I/O
P0.7
GND
NC
D I/O or A In Port 0.7. See Section 13 for complete description.
11
—
3
Ground.
4, 9, 11
No Connection
26
Rev. 0.5
C8051T600/1/2/3/4/5
C2D /
P0.7
VREF /
P0.0
P0.6 /
CNVSTR
P0.1
VDD
C2CK /
/RST
GND
VPP /
P0.2
P0.5
P0.4
EXTCLK
/ P0.3
Figure 4.1. QFN-11 Pinout Diagram (Top View)
Rev. 0.5
27
C8051T600/1/2/3/4/5
Bottom View
Table 4.2. QFN-11
Package Dimensions
E2
b
MM
E3
L
Min
0.80
0
0
—
0.18
—
—
—
—
Typ
0.90
0.02
0.65
0.25
0.23
3.00
2.20
2.00
0.386
3.00
1.36
1.135
0.5
Max
1.00
0.05
1.00
—
0.30
—
2.25
—
—
—
—
—
A
A1
A2
A3
b
D
D2
D3
D4
E
E2
E3
e
R
—
—
—
—
—
k
k
L
LB
LT
R
—
0.45
—
—
0.09
0.27
0.55
0.36
0.37
—
—
0.65
—
—
—
e
E
Side E View
e
Side D View
e
Figure 4.2. QFN-11 Package Drawing
28
Rev. 0.5
C8051T600/1/2/3/4/5
TOP VIEW
1
2
3
4
5
6
7
14
13
12
11
10
9
P0.6
C2D/P0.7
GND
C2CK/RST
P0.5
P0.4
N/C
N/C
P0.0
P0.3
P0.1
N/C
8
VDD
P0.2/VPP
Figure 4.3. SOIC-14 Pinout Diagram (Top View)
Rev. 0.5
29
C8051T600/1/2/3/4/5
Table 4.3. SOIC-14 Package
Dimensions
D
MM
Min
1.35
0.10
1.25
0.31
Typ
—
—
—
—
Max
1.75
0.25
1.65
0.51
14
8
7
A
A1
A2
b
D
E
E1
e
L
E1 E
8.65 BSC
6.00 BSC
3.90 BSC
1.27
PIN 1
IDENTIFIER
1
—
0.40
—
1.27
Top View
—
L1
1.04 REF
A2
A
L
A1
L1
b
e
Side View
Figure 4.4. SOIC-14 Package Drawing
30
Rev. 0.5
C8051T600/1/2/3/4/5
5. ADC0 - 10-Bit SAR ADC (C8051T600/2/4 Only)
The ADC0 subsystem for the C8051T600/2/4 devices consists an analog multiplexer (referred to as
AMUX0) with 10 input selection options, a gain stage programmable to 1x or 0.5x, and a 500 ksps, 10-bit
successive-approximation-register (SAR) ADC with integrated track-and-hold and programmable window
detector (see block diagram in Figure 5.1). The multiplexer, data conversion modes and window detector
are all configurable under software control via the Special Function Registers shown in Figure 5.1. ADC0
may be configured to measure any Port pin, the Temperature Sensor output, or VDD with respect to GND.
The ADC0 subsystem is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set
to logic 1. The ADC0 subsystem remains in a low power shutdown state when this bit is logic 0. A special
8-bit mode is also provided for backwards-compatibility with the C8051F300 development platform.
ADC0CN
AMX0SL
VDD
000
001
010
011
1xx
AD0BUSY (W)
Timer 0 Overflow
Timer 2 Overflow
Timer 1 Overflow
CNVSTR Input
Start
Conversion
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
10-Bit
SAR
10-to-1
AMUX
X1 or
X0.5
10
ADC
Temp
Sensor
AD0WINT
VDD
Comb.
Logic
20
ADC0LTH:L
ADC0CF
ADC0GTH:L
Figure 5.1. ADC0 Functional Block Diagram
Rev. 0.5
31
C8051T600/1/2/3/4/5
5.1. Analog Multiplexer
The analog multiplexer (AMUX0) selects the positive input to the ADC, allowing any Port pin to be mea-
sured relative to GND. Additionally, the on-chip temperature sensor or the positive power supply (VDD
)
may be selected as the positive ADC input. The ADC0 input channel is selected in the AMX0SL register as
described in Figure 5.3. When an external Voltage Reference is supplied to P0.0 or the internal regulator is
used as VREF, the VDD Voltage supply can be determined by taking a measurement of VDD with the gain
setting at 0.5x.
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, clear the corresponding bit in register P0MDIN to ‘0’. To force the Crossbar to skip a Port pin, set the
corresponding bit in register XBR0 to ‘1’. See Section “13. Port Input/Output” on page 97 for more Port
I/O configuration details.
5.2. Gain Setting
The ADC has gain settings of 1x and 0.5x. In 1x mode, the full scale reading of the ADC is determined
directly by VREF. In 0.5x mode, the full-scale reading of the ADC occurs when the input voltage is VREF x 2.
The 0.5x gain setting can be useful to obtain a higher input Voltage range when using a small VREF volt-
age, or to measure input voltages that are between VREF and VDD. Gain settings for the ADC are con-
trolled by the AMP0GN1–0 bits in register ADC0CF.
5.3. Output Coding
The conversion code format for the ADC is shown below. Conversion codes are represented as 10-bit
unsigned integers. Inputs are measured from ‘0’ to VREF x 1023/1024. All conversions are left-justified in
the ADC0H and ADC0L registers (ADC0H holds the 8 most significant bits, and the two least significant
bits are stored in ADC0L). Example codes are shown below.
Input Voltage
(AIN – GND),
Gain = 1
10-bit Output (Conversion Code)
ADC0H:ADC0L Register Coding
VREF x 1023/1024
0x3FF
0x200
0x100
0x00
0xFF : 0xC0
0x80 : 0x00
0x40 : 0x00
0x00 : 0x00
VREF/2
VREF/4
0
5.4. 8-Bit Compatibility Mode
Setting the ADC08BE bit in register ADC0CF to ‘1’ will put the ADC in 8-bit compatibility mode. This mode
allows backward compatibility with the C8051F300 device family. In 8-bit compatibility mode, only the 8
MSBs of data are converted. The two LSBs of a conversion are always ‘00’ in this mode, and the ADC0L
register will always read back 0x00. 8-bit conversions take two fewer SAR clock cycles than 10-bit conver-
sions, so the conversion is completed faster, and a 500 ksps sampling rate can be achieved with a slower
SAR clock.
32
Rev. 0.5
C8051T600/1/2/3/4/5
5.5. Temperature Sensor
The temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the ADC
input when the temperature sensor is selected by bits AMX0P2–0 in register AMX0SL. Values for the Off-
set and Slope parameters can be found in Table 5.1.
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
Slope (V / deg C)
Offset (V at 0 Celsius)
Temperature
Figure 5.2. Temperature Sensor Transfer Function
5.5.1. Calibration
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature mea-
surements (see Table 5.1 for linearity specifications). For absolute temperature measurements, offset and/
or gain calibration is recommended. Typically a 1-point (offset) calibration includes the following steps:
Step 1. Control/measure the ambient temperature (this temperature must be known).
Step 2. Power the device, and delay for a few seconds to allow for self-heating.
Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input
and GND selected as the negative input.
Step 4. Calculate the offset characteristics, and store this value in non-volatile memory for use
with subsequent temperature sensor measurements.
Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Parame-
ters that affect ADC measurement, in particular the voltage reference value, will also affect temper-
ature measurement.
A single-point offset measurement of the temperature sensor is performed on each device during produc-
tion test. The measurement is performed at 25 °C ±TBD °C, using the ADC with the internal regulator
selected as the Voltage Reference. The direct ADC result of the measurement is stored in the SFR regis-
ters TOFFH and TOFFL, shown in SFR Definition 5.1 and SFR Definition 5.2.
Rev. 0.5
33
C8051T600/1/2/3/4/5
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
-40.00
-20.00
0.00
60.00
80.00
20.00
-1.00
-2.00
-3.00
-4.00
-5.00
Temperature (degrees C)
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (V
= 2.4 V)
REF
SFR Definition 5.1. TOFFH: Temperature Offset Measurement High Byte
R/W
TOFF9
Bit7
R/W
TOFF8
Bit6
R/W
TOFF7
Bit5
R/W
TOFF6
Bit4
R/W
TOFF5
Bit3
R/W
TOFF4
Bit2
R/W
TOFF3
Bit1
R/W
TOFF2
Bit0
Reset Value
Varies
SFR Address:
0xA3
Bits7–0: Bits 9–2 of temperature sensor measurement.
The temperature sensor offset measurement is taken during production test of the device.
The measurement is intended to be used as an offset correction for the temperature sensor.
It is taken under the conditions VREF = VREG; TAMB = 25 °C ± TBD °C. One LSB of the tem-
perature sensor offset measurement is equivalent to one LSB of the ADC output under the
measurement conditions.
34
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 5.2. TOFFL: Temperature Offset Measurement Low Byte
R/W
TOFF1
Bit7
R/W
TOFF0
Bit6
R/W
—
R/W
—
R/W
—
R/W
—
R/W
—
R/W
—
Reset Value
Varies
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA2
Bits7–6: Bits 1-0 of temperature sensor offset measurement.
Bits5–0: Read: 000000b, Write = Don’t Care
The temperature sensor offset measurement is taken during production test of the device.
The measurement is intended to be used as an offset correction for the temperature sensor.
It is taken under the conditions VREF = VREG; TAMB = 25 °C ± TBD °C. One LSB of the
temperature sensor offset measurement is equivalent to one LSB of the ADC output under
the measurement conditions.
Rev. 0.5
35
C8051T600/1/2/3/4/5
5.6. Modes of Operation
ADC0 has a maximum sampling rate of 500 ksps. The ADC0 SAR clock is a divided version of the system
clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by (AD0SC + 1) for
0 ≤ AD0SC ≤ 31).
5.6.1. Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM2–0) in register ADC0CN. Conversions may be initiated by one of the 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 (pin P0.6)
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 register, ADC0, when bit AD0INT is logic 1. Note that when Timer 2
overflows are used as the conversion source, Timer 2 Low Byte overflows are used if Timer 2 is in 8-bit mode;
Timer 2 High byte overflows are used if Timer 2 is in 16-bit mode. See Section “16. Timers” on page 131
for timer configuration.
Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port pin P0.6. When the
CNVSTR input is used as the ADC0 conversion source, Port pin P0.6 should be skipped by the Digital
Crossbar. To configure the Crossbar to skip P0.6, set to ‘1’ Bit6 in register XBR0. See Section “13. Port
Input/Output” on page 97 for details on Port I/O configuration.
36
Rev. 0.5
C8051T600/1/2/3/4/5
5.6.2. 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 5.4 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 Sec-
tion “5.6.3. Settling Time Requirements” on page 38.
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 Compatibility 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 Compatibility 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 Compatibility Mode
1
2 3 4 5 6 7 8 9 10 11 12* 13 14
SAR
Clocks
Track or
Convert
AD0TM = 0
Convert
Track
*Conversion Ends at rising edge of 12th clock in 8-bit Compatibility Mode
Figure 5.4. ADC Tracking and Conversion Timing
Rev. 0.5
37
C8051T600/1/2/3/4/5
5.6.3. Settling Time Requirements
A minimum amount of tracking time is required before each conversion can be performed, to allow the
sampling capacitor voltage to settle. This tracking time is determined by the AMUX0 resistance, the ADC0
sampling capacitance, any external source resistance, and the accuracy required for the conversion. Note
that in delayed tracking mode, an additional 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 require-
ments, and higher values for the external source impedance will increase the required tracking time.
Figure 5.5 shows the equivalent ADC0 input circuit. The required ADC0 settling time for a given settling
accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature Sensor output or
VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum settling time (track/
hold time) requirements.
2n
SA
⎛
⎝
⎞
⎠
------
t = ln
× RTOTALCSAMPLE
Equation 5.1. 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
RTOTAL is the sum of the AMUX0 resistance and any external source resistance.
n is the ADC resolution in bits (10).
MUX Select
P0.x
RMUX = 5k
CSAMPLE = 5pF
RCInput= RMUX * CSAMPLE
Note: When the PGA gain is set to 0.5, CSAMPLE = 3pF
Figure 5.5. ADC0 Equivalent Input Circuits
38
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 5.3. AMX0SL: AMUX0 Channel Select
R/W
-
R/W
-
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
AMX0P3 AMX0P2 AMX0P1 AMX0P0 10000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBB
Bits7–4: Unused.
Bits3–0: AMX0P3–0: AMUX0 Positive Input Selection.
0000–1001b: ADC0 Positive Input selected per the chart below.
1010–1111b: RESERVED.
AMX0P3–0
0000
ADC0 Positive Input
P0.0
0001
P0.1
0010
P0.2
0011
P0.3
0100
P0.4
0101
P0.5
0110
0111
P0.6
P0.7
1000
Temperature Sensor
VDD
1001
Rev. 0.5
39
C8051T600/1/2/3/4/5
SFR Definition 5.4. ADC0CF: ADC0 Configuration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AD08BE AMP0GN1 AMP0GN0 11111000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBC
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in bits AD0SC4–0. SAR Conversion clock require-
ments are given in Table 5.1.
Note: if the OTP Power Controller is enabled (OTPPCE = '1'), AD0SC must be set to at
least "00001" for proper ADC operation.
SYSCLK
CLKSAR
---------------------
AD0SC =
– 1
Bit2:
AD08BE: 8-Bit Mode Enable.
0: ADC operates in 10-bit mode (normal).
1: ADC operates in 8-bit mode.
Bits1–0: AMP0GN1–0: ADC Gain Control Bits.
00: Gain = 0.5
01: Gain = 1
SFR Definition 5.5. ADC0H: ADC0 Data Word High Byte
R/W
D9
Bit7
R/W
D8
R/W
D7
Bit5
R/W
D6
R/W
D5
R/W
D4
Bit2
R/W
D3
R/W
D2
Reset Value
00000000
SFR Address:
0xBE
Bit6
Bit4
Bit3
Bit1
Bit0
Bits7–0: ADC0 Data Word bits 9–2.
ADC0H holds the upper 8 bits of output data from the most recently completed ADC0 con-
version. In 8-bit compatibility mode, the ADC0H register holds all 8 bits of the conversion
data word.
SFR Definition 5.6. ADC0L: ADC0 Data Word Low Byte
R/W
D1
Bit7
R/W
D0
R
-
R
-
R
-
R
-
R
-
R
-
Reset Value
00000000
SFR Address:
0xBD
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–6: ADC0 Data Word bits 1–0.
Bits5–0: Read: 000000b, Write = Don’t Care
ADC0L holds the lowest 2 bits of output data from the most recently completed ADC0 con-
version. In 8-bit compatibility mode, the ADC0L register always returns 0x00.
40
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 5.7. ADC0CN: ADC0 Control
R/W
AD0EN
Bit7
R/W
AD0TM
Bit6
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0INT AD0BUSY AD0WINT AD0CM2 AD0CM1 AD0CM0 00000000
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
Bit Addressable
0xE8
Bit7:
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
AD0TM: ADC0 Track Mode Bit.
Bit6:
0: Normal Track Mode: When ADC0 is enabled, a start-of-conversion signal begins the con-
version. For internal conversion start sources, tracking is continuous whenever a conversion
is not in progress. For external CNVSTR signal, tracking of the input occurs when CNVSTR
is held low.
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.
Bit5:
Bit4:
AD0INT: ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since the last time AD0INT was cleared.
1: ADC0 has completed a data conversion.
AD0BUSY: ADC0 Busy Bit.
Read: Unused.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM2–0 = 000b
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.
Bit3:
Bits2–0: AD0CM2–0: ADC0 Start of Conversion Mode Select.
000: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
001: ADC0 conversion initiated on overflow of Timer 0.
010: ADC0 conversion initiated on overflow of Timer 2.
011: ADC0 conversion initiated on overflow of Timer 1.
1xx: ADC0 conversion initiated on rising edge of external CNVSTR.
Note: Start of conversion is delayed by three SAR clock cycles when AD0TM = 1.
Rev. 0.5
41
C8051T600/1/2/3/4/5
5.7. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output to user-programmed
limits, and notifies the system when a desired condition is detected. This is especially effective in an inter-
rupt-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. Example comparisons are shown in Figure 5.6. Notice that the window detector flag
can be programmed to indicate when measured data is inside or outside of the user-programmed limits
depending on the contents of the ADC0LTH:L and ADC0GTH:L registers.
5.7.1. Window Detector Example
Figure 5.6 shows two example window comparisons, using the ADC in 10-bit 1x gain mode. The ADC out-
put codes represent input voltages (AIN – GND) from 0 V to VREF x (1023/1024) and are represented as
10-bit unsigned integers. Note that the hexadecimal numbers shown are left-justified, 10-bit values. In the
example on the left-hand side, an AD0WINT interrupt will be generated if the ADC0 conversion word
(ADC0H:L) is within the range defined by ADC0GTH:L and ADC0LTH:L (if 0x1000 < ADC0H:L < 0x2000).
In the example on the right-hand side, an AD0WINT interrupt will be generated if ADC0 is outside of the
range defined by ADC0GTH:L and ADC0LTH:L (if ADC0H:L < 0x1000 or ADC0H:L > 0x2000).
ADC0H:L
0xFFC0
ADC0H:L
0xFFC0
Input Voltage
(AIN+ - GND)
Input Voltage
(AIN+ - GND)
REF x (1023/1204)
REF x (1023/1024)
AD0WINT
not affected
AD0WINT=1
0x2040
0x2040
REF x (1/8)
0x2000
0x1FC0
ADC0LTH:L
ADC0GTH:L
REF x (1/8)
0x2000
0x1FC0
ADC0GTH:L
AD0WINT
not affected
AD0WINT=1
0x1040
0x1000
0x1040
0x1000
REF x (1/16)
REF x (1/16)
ADC0LTH:L
0x0FC0
0x0FC0
AD0WINT=1
AD0WINT
not affected
0x0000
0x0000
0
0
Figure 5.6. ADC Window Compare Examples
42
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 5.8. ADC0GTH: ADC0 Greater-Than High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
SFR Address:
0xC4
Bits7–0: ADC0 Greater-Than High Byte.
SFR Definition 5.9. ADC0GTL: ADC0 Greater-Than Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11000000
SFR Address:
0xC3
Bits7–0: ADC0 Greater-Than Low Byte. In 8-bit compatibility mode, this register should be set to 0x00.
SFR Definition 5.10. ADC0LTH: ADC0 Less-Than High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xC6
Bits7–0: ADC0 Less-Than High Byte.
SFR Definition 5.11. ADC0LTL: ADC0 Less-Than Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xC5
Bits7–0: ADC0 Less-Than Low Byte. In 8-bit compatibility mode, this register should be set to 0x00.
Rev. 0.5
43
C8051T600/1/2/3/4/5
Table 5.1. ADC0 Electrical Characteristics
VDD = 3.0 V, VREF = 2.50 V (REFSL = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter
DC Accuracy
Conditions
Min
Typ
Max
Units
Resolution
10
bits
LSB
LSB
LSB
Integral Nonlinearity
Differential Nonlinearity
Offset Error1
—
—
—
±0.5
±0.5
TBD
±1
±1
Guaranteed Monotonic
TBD
Full Scale Error1
—
TBD
TBD
LSB
Dynamic Performance (10 kHz sine-wave input, 1 dB below Full Scale, 500 ksps)
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
Spurious-Free Dynamic Range
Conversion Rate
TBD
—
TBD
TBD
TBD
—
—
—
dB
dB
dB
Up to the 5th harmonic
—
SAR Conversion Clock2,3
—
—
—
8.33
—
MHz
10-bit Mode
8-bit Mode
13
11
clocks
clocks
Conversion Time in SAR Clocks
VDD > 2.0 V
VDD < 2.0 V
300
2.0
—
—
0.3
—
—
—
ns
µs
Track/Hold Acquisition Time
Throughput Rate3
500
ksps
Analog Inputs
Absolute Voltage on External
ADC Input
VDD + 0.3
VREF
GND – 0.3
0
—
—
V
V
Input Voltage Range (Gain = 1x) AIN – GND
1x Gain
SAR Sampling Capacitor
0.5x Gain
—
—
5
3
—
—
pF
pF
Temperature Sensor
Linearity1,4
Slope4
Slope Error1,4
Offset4
—
—
—
—
—
—
—
—
—
—
—
—
TBD
3.2
°C
mV / °C
µV/C
mV
±80
903
±10
Temp = 0 °C
Offset Error1,4
Temp = 0 °C
mV
Power Specifications
Power Supply Current
(VDD supplied to ADC0)
Operating Mode, 500 ksps
—
—
400
900
—
µA
Power Supply Rejection
TBD
mV/V
Notes:
1. Represents mean ± one standard deviation.
2. When using the C8051F300 for code development, SAR clock should be limited to 6 MHz.
3. See Section “18. Revision Specific Behavior” on page 159.
4. Includes ADC offset, gain, and linearity variations.
44
Rev. 0.5
C8051T600/1/2/3/4/5
6. Voltage Reference Options
The voltage reference MUX is configurable to use an externally connected voltage reference, the unregu-
lated power supply voltage (VDD), or the regulated 1.8 V internal supply (see Figure 6.1). The REFSL bit in
the Reference Control register (REF0CN) selects the reference source. For an external source, REFSL
should be set to ‘0’; For VDD as the reference source, REFSL should be set to ‘1’. To override this selec-
tion, and use the internal regulator as the reference source, the REGOVR bit can be set to ‘1’. See
Figure 6.1 for REF0CN register details. The electrical specifications for the voltage reference circuit are
given in Table 6.1.
Important Note About the VREF Input: Port pin P0.0 is used as the external VREF input. When using an
external voltage reference, P0.0 should be configured as analog input and skipped by the Digital Crossbar.
To configure P0.0 as analog input, set to ‘1’ Bit0 in register P0MDIN. To configure the Crossbar to skip
P0.0, set to ‘1’ Bit0 in register XBR0. Refer to Section “13. Port Input/Output” on page 97 for complete
Port I/O configuration details. The external reference voltage must be within the range 0 ≤ VREF ≤ VDD
.
On C8051T600/2 devices, the temperature sensor connects to the highest order input of the ADC0 positive
input multiplexer (see Section “5.1. Analog Multiplexer” on page 32 for details). The TEMPE bit in regis-
ter REF0CN enables/disables the temperature sensor. While disabled, the temperature sensor defaults to
a high impedance state and any ADC0 measurements performed on the sensor result in meaningless
data.
REF0CN
EN
VDD
Temp Sensor
To Analog Mux
External
Voltage
Reference
Circuit
R1
REGOVR
0
VREF
0
1
GND
VREF
(to ADC)
VDD
Internal
Regulator
1
Figure 6.1. Voltage Reference Functional Block Diagram
Rev. 0.5
45
C8051T600/1/2/3/4/5
SFR Definition 6.1. REF0CN: Reference Control
R/W
—
R/W
—
R/W
—
R/W
R/W
R/W
TEMPE
Bit2
R/W
—
R/W
—
Reset Value
00000000
SFR Address:
0xD1
REGOVR REFSL
Bit7
Bit6
Bit5
Bit4
Bit3
Bit1
Bit0
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bit4:
REGOVR: Regulator Reference Override.
This bit “overrides” the REFSL bit, and allows the internal regulator to be used as a refer-
ence source.
0: The voltage reference source is selected by the REFSL bit.
1: The internal regulator is used as the voltage reference, regardless of the REFSL setting.
REFSL: Voltage Reference Select.
This bit selects the source for the internal voltage reference when REGOVR is set to ‘0’.
0: VREF input pin used as voltage reference.
Bit3:
Bit2:
1: VDD used as voltage reference.
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
Bits1-0: UNUSED. Read = 00b. Write = don’t care.
Table 6.1. External Voltage Reference Circuit Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C unless otherwise specified.
Parameter
Input Voltage Range
Input Current
Conditions
Min
0
Typ
—
Max
Units
V
VDD
Sample Rate = 500 ksps; VREF = 2.5 V
—
12
—
µA
46
Rev. 0.5
C8051T600/1/2/3/4/5
7. Comparator0
C8051T600/1/2/3/4/5 devices include an on-chip programmable voltage comparator, which is shown in
Figure 7.1. Comparator0 offers programmable response time and hysteresis, an analog input multiplexer,
and two outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0), or an
asynchronous “raw” output (CP0A). The asynchronous CP0A signal is available even when the system
clock is not active. This allows Comparator0 to operate and generate an output with the device in STOP
mode (when the internal regulator is still active). When assigned to a Port pin, the Comparator0 output may
be configured as open drain or push-pull (see Section “13.2. Port I/O Initialization” on page 99).
Comparator0 may also be used as a reset source (see Section “10.5. Comparator0 Reset” on page 83).
The inputs for Comparator0 are selected in the CPT0MX register (SFR Definition 7.2). The CMX0P1–
CMX0P0 bits select the Comparator0 positive input; the CMX0N1–CMX0N0 bits select the Comparator0
negative input.
Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be con-
figured as analog inputs in their associated Port configuration register, and configured to be skipped by the
Crossbar (for details on Port configuration, see Section “13.3. General Purpose Port I/O” on page 102).
CP0EN
CP0OUT
CP0RIF
CP0FIF
VDD
CP0HYP1
CP0HYP0
CP0HYN1
CP0HYN0
CMX0N1
CMX0N0
CMX0P1
CMX0P0
CP0
Rising-edge
Interrupt Flag
CP0
Falling-edge
Interrupt Flag
P0.0
P0.2
P0.4
P0.6
CP0 +
Interrupt
Logic
CP0
+
-
SET
CLR
SET
CLR
D
Q
Q
D
Q
Q
Crossbar
P0.1
P0.3
P0.5
P0.7
(SYNCHRONIZER)
GND
CP0 -
CP0A
Reset
Decision
Tree
CP0MD1
CP0MD0
Figure 7.1. Comparator0 Functional Block Diagram
Rev. 0.5
47
C8051T600/1/2/3/4/5
The output of Comparator0 can be polled in software, used as an interrupt source, and/or routed to a Port
pin. When routed to a Port pin, the Comparator0 output is available asynchronous or synchronous to the
system clock; the asynchronous output is available even in STOP mode (with no system clock active).
When disabled, the Comparator0 output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic
low state. See Section “13.1. Priority Crossbar Decoder” on page 98 for details on configuring the
Comparator0 output via the digital Crossbar. Comparator0 inputs can be externally driven from –0.25 V to
(VDD + 0.25 V) without damage or upset. The complete electrical specifications for Comparator0 are given
in Table 7.1.
The Comparator0 response time may be configured in software via the CP0MD1–0 bits in register
CPT0MD (see SFR Definition 7.3). Selecting a longer response time reduces the amount of power con-
sumed by Comparator0. See Table 7.1 for complete timing and power consumption specifications.
CP0+
VIN+
VIN-
+
CP0
_
OUT
CP0-
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
Negative Hysteresis Voltage
INPUTS
(Programmed by CP0HYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Maximum
Negative Hysteresis
Positive Hysteresis
Disabled
Maximum
Positive Hysteresis
Figure 7.2. Comparator Hysteresis Plot
The hysteresis of Comparator0 is software-programmable via its Comparator0 Control register (CPT0CN).
The user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive
and negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator0 hysteresis is programmed using Bits3–0 in the Comparator0 Control Register CPT0CN
(shown in SFR Definition 7.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. The amount of positive hysteresis can be programmed using the CP0HYP bits.
Comparator0 interrupts can be generated on both rising-edge and falling-edge output transitions. (For
Interrupt enable and priority control, see Section “9.3. Interrupt Handler” on page 70). The CP0FIF flag
is set to logic 1 upon a Comparator0 falling-edge interrupt, and the CP0RIF flag is set to logic 1 upon the
48
Rev. 0.5
C8051T600/1/2/3/4/5
Comparator0 rising-edge interrupt. Once set, these bits remain set until cleared by software. The output
state of Comparator0 can be obtained at any time by reading the CP0OUT bit. Comparator0 is enabled by
setting the CP0EN bit to logic 1, and is disabled by clearing this bit to logic 0.
SFR Definition 7.1. CPT0CN: Comparator0 Control
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF8
Bit7:
CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6:
Bit5:
Bit4:
CP0OUT: Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
CP0RIF: Comparator0 Rising-Edge Interrupt Flag.
0: No Comparator0 Rising Edge Interrupt has occurred since this flag was last cleared.
1: Comparator0 Rising Edge Interrupt has occurred.
CP0FIF: Comparator0 Falling-Edge Interrupt Flag.
0: No Comparator0 Falling-Edge Interrupt has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge Interrupt has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev. 0.5
49
C8051T600/1/2/3/4/5
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection
R/W
—
R/W
—
R/W
R/W
R/W
—
R/W
—
R/W
R/W
Reset Value
CMX0N1 CMX0N0
CMX0P1 CMX0P0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9F
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bits6–4: CMX0N1–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
CMX0N1 CMX0N0 Negative Input
0
0
1
1
0
1
0
1
P0.1
P0.3
P0.5
P0.7
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CMX0P1–CMX0P0: Comparator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
CMX0P1 CMX0P0 Positive Input
0
0
1
1
0
1
0
1
P0.0
P0.2
P0.4
P0.6
50
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection
R/W
—
R/W
—
R/W
—
R/W
—
R/W
—
R/W
—
R/W
R/W
Reset Value
CP0MD1 CP0MD0 00000010
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9D
Bits7–2: UNUSED. Read = 000000b, Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select.
These bits select the response time and power consumption for Comparator0.
Mode
CP0MD1 CP0MD0
CP0 Response Time / Power Setting*
0
1
2
3
0
0
1
1
0
1
0
1
Fastest Response Time
—
—
Lowest Power Consumption
*Note: See Table 7.1 for response time and power consumption values.
Rev. 0.5
51
C8051T600/1/2/3/4/5
Table 7.1. Comparator0 Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherwise specified.
Parameter
Response Time:
Conditions
Min
—
—
—
—
—
—
—
—
Typ
100
Max
—
Units
ns
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
Mode 0, Vcm* = 1.5 V
250
—
ns
175
—
ns
Response Time:
Mode 1, Vcm* = 1.5 V
500
—
ns
320
—
ns
Response Time:
Mode 2, Vcm* = 1.5 V
1100
1050
5200
—
ns
—
ns
Response Time:
Mode 3, Vcm* = 1.5 V
—
ns
Common-Mode Rejection
Ratio
—
1.5
TBD
mV/V
Positive Hysteresis 1
Positive Hysteresis 2
Positive Hysteresis 3
Positive Hysteresis 4
Negative Hysteresis 1
Negative Hysteresis 2
Negative Hysteresis 3
Negative Hysteresis 4
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
5
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
mV
mV
mV
mV
mV
mV
mV
mV
TBD
TBD
TBD
—
10
20
0
TBD
TBD
TBD
5
10
20
VDD
0.25
+
Inverting or Non-Inverting
Input Voltage Range
–0.25
—
V
Input Capacitance
Input Bias Current
Input Offset Voltage
—
–5
–5
7
0.001
—
—
pF
nA
TBD
TBD
mV
Power Supply
Power Supply Rejection
Powerup Time
—
—
—
—
—
—
0.1
10
TBD
—
mV/V
µs
Mode 0
Mode 1
Mode 2
Mode 3
20
—
µA
8.3
2.6
0.5
—
µA
Supply Current at DC
—
µA
—
µA
*Note: Vcm is the common-mode voltage on CP0+ and CP0–.
52
Rev. 0.5
C8051T600/1/2/3/4/5
8. Voltage Regulator (REG0)
C8051T600/1/2/3/4/5 devices include an internal voltage regulator (REG0) to regulate the internal core
supply to 1.8 V from a VDD supply of 1.8 to 3.6 V. Two power-saving modes are built into the regulator to
help reduce current consumption in low-power applications. These modes are accessed through the
REG0CN register (SFR Definition 8.1). Electrical characteristics for the on-chip regulator are specified in
Table 8.1
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 VDD. Doing so could cause permanent damage to the
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
and a full power cycle of the device are the only methods of generating a reset.
Rev. 0.5
53
C8051T600/1/2/3/4/5
SFR Definition 8.1. REG0CN: Voltage Regulator Control
R/W
R/W
R/W
—
R/W
—
R/W
—
R/W
—
R/W
—
R/W
Reset Value
STOPCF BYPASS
OTPPCE 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC7
Bit 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, Supply Monitor or power cycle
can reset the device.
Bit 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 VDD supply pin.
0: Normal Mode - Regulator is on.
1: Bypass Mode - Regulator is off, and the microcontroller core operates directly from the
VDD supply voltage.
IMPORTANT: Bypass mode is for use with an external regulator as the supply voltage
only. Never place the regulator in bypass mode when the VDD supply voltage is
greater than the specifications given in Table 2.1 on page 23. Doing so may cause
permanent damage to the device.
Bits 5–1 RESERVED. Must Always Write 00000b.
Bit 0
OTPPCE: OTP Power Controller Enable.
This bit can help the system save power at slower system clock frequencies (about 2 MHz or
less) by automatically shutting down the OTP memory between clocks when information is
not being fetched from the OTP memory.
0: Normal Mode - OTP power controller disabled (OTP memory is always on).
1: Low Power Mode - OTP power controller enabled (OTP memory turns on/off as needed).
Note: If an external clock source is used with the OTP Power Controller enabled, and the
clock frequency changes from slow (<2 MHz) to fast (>2 MHz), the OTP power will turn on,
and up to 20 clocks may be "skipped" to ensure that the OTP power is stable before reading
memory.
Table 8.1. Internal Voltage Regulator Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Input Voltage Range
Bias Current
Conditions
Min
1.8
—
Typ
—
Max
3.6
—
Units
V
Normal Mode
TBD
µA
54
Rev. 0.5
C8051T600/1/2/3/4/5
9. 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. Included are
three 16-bit counter/timers (see description in Section 16), an enhanced full-duplex UART (see description
in Section 15), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (Sec-
tion 9.2.6), and one byte-wide I/O Port (see description in Section 13). The CIP-51 also includes on-chip
debug hardware (see description in Section 19), and interfaces directly with the analog and digital sub-
systems providing a complete data acquisition or control-system solution in a single integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 9.1 for a block diagram).
The CIP-51 includes the following features:
- Fully Compatible with MCS-51 Instruction Set
- 25 MIPS Peak Throughput with 25 MHz Clock
- 0 to 25 MHz Clock Frequency
- Extended Interrupt Handler
- Reset Input
- Power Management Modes
- On-chip Debug Logic
- 256 Bytes of Internal RAM
- Byte-Wide I/O Port
- Program and Data Memory Security
DATA BUS
ACCUMULATOR
B
REGISTER
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
SRAM
(256 X 8)
PSW
ALU
DATA BUS
SFR_ADDRESS
SFR_CONTROL
D8
BUFFER
SFR
BUS
INTERFACE
D8
SFR_WRITE_DATA
SFR_READ_DATA
D8
DATA POINTER
PC INCREMENTER
D8
MEM_ADDRESS
MEM_CONTROL
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
PIPELINE
MEMORY
INTERFACE
A16
D8
MEM_WRITE_DATA
MEM_READ_DATA
CONTROL
LOGIC
RESET
CLOCK
SYSTEM_IRQs
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
STOP
IDLE
POWER CONTROL
REGISTER
D8
Figure 9.1. CIP-51 Block Diagram
Rev. 0.5
55
C8051T600/1/2/3/4/5
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.
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 for each execution time.
Clocks to Execute
Number of Instructions
1
26
2
50
2/3
5
3
14
3/4
7
4
3
4/5
1
5
2
8
1
Programming and Debugging Support
In-system programming of the program memory and communication with on-chip debug support logic is
accomplished via the Silicon Labs 2-Wire Development Interface (C2).
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints, starting, stopping and single stepping through program execution (including interrupt service
routines), examination of the program's call stack, and reading/writing the contents of registers. This
method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or other on-chip
resources. C2 details can be found in Section “19. C2 Interface” on page 161.
The C8051F300 can be used as a code development platform. The C8051F300 utilizes the same pinout,
and can operate with the same firmware, but contains re-programmable Flash memory, allowing for quick
development of code.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs pro-
vides an integrated development environment (IDE) including editor, debugger and programmer. The IDE's
debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient in-sys-
tem device programming and debugging. Third party macro assemblers and C compilers are also avail-
able.
9.1. 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.
9.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock
cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 9.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
56
Rev. 0.5
C8051T600/1/2/3/4/5
Table 9.1. CIP-51 Instruction Set Summary
Clock
Cycles
Mnemonic
Description
Bytes
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
Add register to 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
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
INC Rn
Increment register
INC direct
Increment direct byte
INC @Ri
Increment indirect RAM
Decrement A
DEC A
DEC Rn
Decrement register
DEC direct
DEC @Ri
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
INC DPTR
MUL AB
DIV AB
Divide A by B
DA A
Decimal adjust A
Rev. 0.5
57
C8051T600/1/2/3/4/5
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Clock
Cycles
Mnemonic
Description
Bytes
Logical Operations
ANL A, Rn
AND Register to A
1
2
1
2
2
3
1
2
1
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
1
2
2
2
2
3
1
2
2
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
ANL A, direct
ANL A, @Ri
AND direct byte to A
AND indirect RAM to A
AND immediate to A
ANL A, #data
ANL direct, A
ANL direct, #data
ORL A, Rn
AND A to direct byte
AND immediate to direct byte
OR Register to A
ORL A, direct
ORL A, @Ri
ORL A, #data
ORL direct, A
ORL direct, #data
XRL A, Rn
OR direct byte to A
OR indirect RAM to A
OR immediate to A
OR A to direct byte
OR immediate to direct byte
Exclusive-OR Register to A
Exclusive-OR direct byte to A
Exclusive-OR indirect RAM to A
Exclusive-OR immediate to A
Exclusive-OR A to direct byte
Exclusive-OR immediate to direct byte
Clear A
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
XRL direct, #data
CLR A
CPL A
Complement A
RL A
Rotate A left
RLC A
Rotate A left through Carry
Rotate A right
RR A
RRC A
Rotate A right through Carry
Swap nibbles of A
SWAP A
Data Transfer
MOV A, Rn
Move Register to A
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
2
2
2
1
2
2
2
2
3
2
3
2
2
2
3
3
3
3
3
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
Move direct byte to A
Move indirect RAM to A
Move immediate to A
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
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)
58
Rev. 0.5
C8051T600/1/2/3/4/5
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Clock
Cycles
Mnemonic
Description
Bytes
*MOVX A, @DPTR
*MOVX @DPTR, A
PUSH direct
POP direct
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
1
1
2
2
1
2
1
1
3
3
2
2
1
2
2
2
Pop direct byte from stack
XCH A, Rn
Exchange Register with A
XCH A, direct
XCH A, @Ri
XCHD A, @Ri
Boolean Manipulation
CLR C
Exchange direct byte with A
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
Clear Carry
1
2
1
2
1
2
2
2
2
2
2
2
2
2
3
3
3
1
2
CLR bit
Clear direct bit
SETB C
Set Carry
1
SETB bit
Set direct bit
2
CPL C
Complement Carry
1
CPL bit
Complement direct bit
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
2
ANL C, bit
2
ANL C, /bit
2
ORL C, bit
2
ORL C, /bit
MOV C, bit
2
2
MOV bit, C
2
JC rel
2/3
2/3
3/4
3/4
3/4
JNC rel
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
JB bit, rel
JNB bit, rel
JBC bit, rel
Program Branching
ACALL addr11
LCALL addr16
RET
Absolute subroutine call
2
3
1
1
2
3
2
1
2
2
3
3
3
3
2
3
1
3
4
Long subroutine call
Return from subroutine
5
RETI
Return from interrupt
5
AJMP addr11
LJMP addr16
SJMP rel
Absolute jump
3
Long jump
4
Short jump (relative address)
Jump indirect relative to DPTR
Jump if A equals zero
3
JMP @A+DPTR
JZ rel
3
2/3
2/3
3/4
3/4
3/4
4/5
2/3
3/4
1
JNZ rel
Jump if A does not equal zero
Compare direct byte to A and jump if not equal
Compare immediate to A and jump if not equal
Compare immediate to Register and jump if not equal
Compare immediate to indirect and jump if not equal
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
CJNE A, direct, rel
CJNE A, #data, rel
CJNE Rn, #data, rel
CJNE @Ri, #data, rel
DJNZ Rn, rel
DJNZ direct, rel
NOP
*Note: MOVX instructions are implemented within the CIP-51 core, though no XRAM space is available on these
devices.
Rev. 0.5
59
C8051T600/1/2/3/4/5
Notes on Registers, Operands and Addressing Modes:
Rn—Register R0–R7 of the currently selected register bank.
@Ri—Data RAM location addressed indirectly through R0 or R1.
rel—8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct—8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00–
0x7F) or an SFR (0x80–0xFF).
#data—8-bit constant
#data16—16-bit constant
bit—Direct-accessed bit in Data RAM or SFR
addr11—11-bit destination address used by ACALL and AJMP. The destination must be within the
same 2 kB page of program memory as the first byte of the following instruction.
addr16—16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 8 kB program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
60
Rev. 0.5
C8051T600/1/2/3/4/5
9.2. Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. The CIP-51 memory organization is
shown in Figure 9.2 and Figure 9.3.
9.2.1. Program Memory
The CIP-51 core has a 64 kB program memory space. The C8051T600/1 implements 8192 bytes of this
program memory space as in-system, OTP EPROM, organized in a contiguous block from addresses
0x0000 to 0x1FFF. Note: 512 bytes (0x1E00 – 0x1FFF) of this memory are reserved for factory use and
are not available for user program storage. The C8051T602/3 implements 4096 bytes of OTP EPROM pro-
gram memory space; the C8051T604/5 implements 2048 bytes of OTP EPROM program memory space.
Figure 9.2 shows the program memory maps for C8051T600/1/2/3/4/5 devices.
C8051T600/1
C8051T602/3
C8051T604/5
0x1FFF
0x1FFF
0x1FFE
0x1FFF
0x1FFE
Security Byte
Security Byte
Security Byte
0x1FFE
0x1E00
0x1DFF
Reserved
Reserved
Reserved
0x1000
0x0FFF
7680 Bytes
OTP Memory
4096 Bytes
OTP Memory
0x0800
0x07FF
2048 Bytes
OTP Memory
0x0000
0x0000
0x0000
Figure 9.2. Program Memory Maps
Program memory is read-only from within firmware. Individual program memory bytes can be read using
the MOVC instruction. This facilitates the use of OTP EPROM space for constant storage.
Rev. 0.5
61
C8051T600/1/2/3/4/5
9.2.2. Data Memory
The CIP-51 includes 256 bytes of internal RAM mapped into the data memory space from 0x00 through
0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad mem-
ory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Loca-
tions 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 9.3 illustrates the data memory organization of the CIP-51.
INTERNAL DATA ADDRESS SPACE
0xFF
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Register's
(Direct Addressing Only)
0x80
0x7F
(Direct and Indirect
Addressing)
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
0x2F
Bit Addressable
0x20
0x1F
General Purpose
Registers
0x00
Figure 9.3. Data Memory Map
9.2.3. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of 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 Figure 9.4). This allows fast context
switching when entering subroutines and interrupt service routines. Indirect addressing modes use regis-
ters R0 and R1 as index registers.
62
Rev. 0.5
C8051T600/1/2/3/4/5
9.2.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or 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.
9.2.5. 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, 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The stack depth can extend up
to 256 bytes.
9.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional
SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 9.2 lists the SFRs imple-
mented in the CIP-51 System Controller.
The SFR registers are accessed anytime the direct addressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are 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 9.3, for a detailed description of each register.
Rev. 0.5
63
C8051T600/1/2/3/4/5
Table 9.2. Special Function Register (SFR) Memory Map
F8 CPT0CN
F0
PCA0L
PCA0H PCA0CPL0 PCA0CPH0
B
P0MDIN
EIP1
EIE1
E8 ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2
E0 ACC XBR0 XBR1 XBR2 IT01CF
D8 PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2
D0 PSW REF0CN
C8 TMR2CN
C0 SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH REG0CN
RSTSRC
TMR2RLL TMR2RLH
TMR2L
TMR2H
B8
B0
A8
A0
IP
AMX0SL
OSCICL
ADC0CF
ADC0L
ADC0H
OSCXCN
SBUF0
OSCICN
TOFFL
IE
TOFFH
P0MDOUT
98 SCON0
90
CPT0MD
TH1
CPT0MX
88
80
TCON
P0
TMOD
SP
TL0
DPL
2(A)
TL1
DPH
3(B)
TH0
4(C)
CKCON
6(E)
PCON
7(F)
0(8)
1(9)
5(D)
(bit addressable)
64
Rev. 0.5
C8051T600/1/2/3/4/5
Table 9.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
ACC
Address
0xE0
0xBC
0xE8
0xC4
0xC3
0xC6
0xC5
0xBE
0xBD
0xBB
0xF0
0x8E
0xF8
0x9D
0x9F
0x83
0x82
0xE6
0xF6
0xA8
0xB8
0xE4
0xB3
0xB2
0xB1
0x80
0xF1
0xA4
0xD8
0xD9
0xFC
0xEA
0xEC
0xFB
0xE9
0xEB
0xDA
0xDB
Description
Page #
69
Accumulator
ADC0CF
ADC0CN
ADC0GTH
ADC0GTL
ADC0LTH
ADC0LTL
ADC0H
ADC0L
ADC0 Configuration
40
ADC0 Control
41
ADC0 Greater-Than Compare High Byte
ADC0 Greater-Than Compare Low Byte
ADC0 Less-Than Compare High Byte
ADC0 Less-Than Compare Low Byte
ADC0 Data Word High Byte
ADC0 Data Word Low Byte
ADC0 Multiplexer Channel Select
B Register
43
43
43
43
40
40
AMX0SL
B
39
69
CKCON
CPT0CN
CPT0MD
CPT0MX
DPH
Clock Control
137
49
Comparator0 Control
Comparator0 Mode Selection
Comparator0 MUX Selection
Data Pointer High
51
50
67
DPL
Data Pointer Low
67
EIE1
Extended Interrupt Enable 1
External Interrupt Priority 1
Interrupt Enable
75
EIP1
76
IE
73
IP
Interrupt Priority
74
IT01CF
INT0/INT1 Configuration Register
Internal Oscillator Calibration
Internal Oscillator Control
External Oscillator Control
Port 0 Latch
77
OSCICL
OSCICN
OSCXCN
P0
92
92
94
103
103
103
154
155
158
158
158
158
158
158
156
156
P0MDIN
P0MDOUT
PCA0CN
PCA0MD
PCA0CPH0
PCA0CPH1
PCA0CPH2
PCA0CPL0
PCA0CPL1
PCA0CPL2
PCA0CPM0
PCA0CPM1
Port 0 Input Mode Configuration
Port 0 Output Mode Configuration
PCA Control
PCA Mode
PCA Capture 0 High
PCA Capture 1 High
PCA Capture 2 High
PCA Capture 0 Low
PCA Capture 1 Low
PCA Capture 2 Low
PCA Module 0 Mode Register
PCA Module 1 Mode Register
Rev. 0.5
65
C8051T600/1/2/3/4/5
Table 9.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
PCA0CPM2
PCA0H
PCA0L
PCON
Address
0xDC
0xFA
0xF9
0x87
0xD0
0xD1
0xC7
0xEF
0x99
0x98
0xC1
0xC0
0xC2
0x81
0xC8
0x88
0x8C
0x8D
0x8A
0x8B
0x89
0xCB
0xCA
0xCD
0xCC
0xA3
0xA2
0xE1
0xE2
0xE3
Description
Page #
156
157
157
79
PCA Module 2 Mode Register
PCA Counter High
PCA Counter Low
Power Control
PSW
Program Status Word
Voltage Reference Control
Voltage Regulator Control
Reset Source Configuration/Status
UART 0 Data Buffer
68
REF0CN
REG0CN
RSTSRC
SBUF0
SCON0
SMB0CF
SMB0CN
SMB0DAT
SP
46
54
85
129
128
112
114
116
67
UART 0 Control
SMBus Configuration
SMBus Control
SMBus Data
Stack Pointer
TMR2CN
TCON
Timer/Counter 2 Control
Timer/Counter Control
Timer/Counter 0 High
Timer/Counter 1 High
Timer/Counter 0 Low
Timer/Counter 1 Low
Timer/Counter Mode
141
135
138
138
138
138
136
142
142
142
142
34
TH0
TH1
TL0
TL1
TMOD
TMR2RLH
TMR2RLL
TMR2H
TMR2L
TOFFH
TOFFL
XBR0
Timer/Counter 2 Reload High
Timer/Counter 2 Reload Low
Timer/Counter 2 High
Timer/Counter 2 Low
Temperature Sensor Offset Measurement High
Temperature Sensor Offset Measurement Low
Port I/O Crossbar Control 0
Port I/O Crossbar Control 1
Port I/O Crossbar Control 2
Reserved
35
100
101
102
XBR1
XBR2
All other SFR locations
66
Rev. 0.5
C8051T600/1/2/3/4/5
9.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should only be set to the value indicated in the register description. Future product versions may use these
bits to implement new features in which case the reset value of the bit will select the feature's default state.
Detailed descriptions of the remaining SFRs are included in the sections of the data sheet associated with
their corresponding system function.
SFR Definition 9.1. DPL: Data Pointer Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x82
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR.
SFR Definition 9.2. DPH: Data Pointer High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x83
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR.
SFR Definition 9.3. SP: Stack Pointer
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000111
SFR Address:
0x81
Bits7–0: SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
Rev. 0.5
67
C8051T600/1/2/3/4/5
SFR Definition 9.4. PSW: Program Status Word
R/W
CY
Bit7
R/W
AC
Bit6
R/W
F0
R/W
RS1
Bit4
R/W
RS0
Bit3
R/W
OV
Bit2
R/W
F1
R
Reset Value
PARITY 00000000
Bit5
Bit1
Bit0
SFR Address:
(bit addressable)
0xD0
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to logic 0 by all other arithmetic operations.
AC: Auxiliary Carry Flag
Bit6:
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to logic 0 by all other arithmetic opera-
tions.
Bit5:
F0: User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1-RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
RS0
Register Bank
Address
0x00–0x07
0x08–0x0F
0x10–0x17
0x18–0x1F
0
0
1
1
0
1
0
1
0
1
2
3
Bit2:
OV: Overflow Flag.
The OV flag is set to 1 under the following circumstances:
- An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
- A MUL instruction results in an overflow (result is greater than 255).
- A DIV instruction causes a divide-by-zero condition.
The OV flag is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other
cases.
Bit1:
Bit0:
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.
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SFR Definition 9.5. ACC: Accumulator
R/W
ACC.7
Bit7
R/W
ACC.6
Bit6
R/W
ACC.5
Bit5
R/W
ACC.4
Bit4
R/W
ACC.3
Bit3
R/W
ACC.2
Bit2
R/W
ACC.1
Bit1
R/W
Reset Value
ACC.0 00000000
Bit0
SFR Address:
(bit addressable)
0xE0
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
SFR Definition 9.6. B: B Register
R/W
B.7
Bit7
R/W
B.6
Bit6
R/W
B.5
Bit5
R/W
B.4
Bit4
R/W
B.3
Bit3
R/W
B.2
Bit2
R/W
B.1
Bit1
R/W
B.0
Reset Value
00000000
SFR Address:
0xF0
Bit0
(bit addressable)
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
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9.3. Interrupt Handler
The CIP-51 includes an extended interrupt system supporting a total of 12 interrupt sources with two prior-
ity levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies
according to the specific version of the device. Each interrupt source has one or more associated interrupt-
pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition,
the associated interrupt-pending flag is set to logic 1.
If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a 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 the EA bit should be immediately followed by an instruction that has two
or more opcode bytes. For example:
// in 'C':
EA = 0;
EA = 0;
// clear EA bit
// ... followed by another 2-byte opcode
; in assembly:
CLR EA
CLR EA
; clear EA bit
; ... followed by another 2-byte opcode
If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears
the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. How-
ever, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is
followed by a multi-cycle instruction, the interrupt will not be taken.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
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9.3.1. MCU Interrupt Sources and Vectors
The MCUs support 12 interrupt sources. Software can simulate an interrupt by setting any interrupt-pend-
ing 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, associ-
ated vector addresses, priority order and control bits are summarized in Table 9.4 on page 72. 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).
9.3.2. External Interrupts
The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensi-
tive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT1 bits in TCON (Section “16.1. Timer 0 and Timer 1” on page 131) select level
or edge sensitive. The table below lists the possible configurations.
IT0
1
1
0
0
IN0PL
/INT0 Interrupt
IT1
1
1
0
0
IN1PL
/INT1 Interrupt
0
1
0
1
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
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 9.11).
Note that /INT0 and /INT1 Port pin assignments are independent of any Crossbar assignments. /INT0 and
/INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin
via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the
selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section
“13.1. Priority Crossbar Decoder” on page 98 for complete details on configuring the Crossbar).
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the /INT0 and /INT1 external
interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corre-
sponding 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 inac-
tive. The external interrupt source must hold the input active until the interrupt request is recognized. It
must then deactivate the interrupt request before execution of the ISR completes or another interrupt
request will be generated.
9.3.3. 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 9.4.
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9.3.4. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5
system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no
other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
Table 9.4. Interrupt Summary
Interrupt Priority
Enable
Flag
Priority
Control
Interrupt Source
Pending Flag
Vector
Order
Always
Enabled
Always
Highest
Reset
0x0000
Top
None
N/A N/A
External Interrupt 0 (/INT0) 0x0003
Timer 0 Overflow 0x000B
External Interrupt 1 (/INT1) 0x0013
0
1
2
3
IE0 (TCON.1)
TF0 (TCON.5)
IE1 (TCON.3)
TF1 (TCON.7)
RI0 (SCON0.0)
TI0 (SCON0.1)
TF2H
Y
Y
Y
Y
Y
Y
Y
Y
EX0 (IE.0) PX0 (IP.0)
ET0 (IE.1) PT0 (IP.1)
EX1 (IE.2) PX1 (IP.2)
ET1 (IE.3) PT1 (IP.3)
Timer 1 Overflow
0x001B
UART0
0x0023
4
Y
N
ES0 (IE.4) PS0 (IP.4)
(TMR2CN.7)
TF2L
Timer 2 Overflow
0x002B
5
Y
N
ET2 (IE.5) PT2 (IP.5)
(TMR2CN.6)
ESMB0
(EIE1.0)
EWADC0 PWADC0
(EIE1.1) (EIP1.1)
EADC0C PADC0C
PSMB0
(EIP1.0)
SMBus Interface
0x0033
0x003B
0x0043
6
7
8
SI (SMB0CN.0)
Y
Y
Y
N
N
N
AD0WINT
(ADC0CN.3)
AD0INT
(ADC0CN.5)
CF (PCA0CN.7)
CCFn
ADC0 Window Compare
ADC0 Conversion
Complete
(EIE1.2)
(EIP1.2)
Programmable Counter
Array
EPCA0
(EIE1.3)
PPCA0
(EIP1.3)
0x004B
9
Y
N
(PCA0CN.n)
CP0FIF
(CPT0CN.4)
CP0RIF
ECP0F
(EIE1.4)
ECP0R
(EIE1.5)
PCP0F
(EIP1.4)
PCP0R
(EIP1.5)
Comparator0 Falling Edge
Comparator0 Rising Edge
0x0053
0x005B
10
11
N
N
N
N
(CPT0CN.5)
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9.3.5. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the
data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
SFR Definition 9.7. IE: Interrupt Enable
R/W
EA
Bit7
R/W
IEGF0
Bit6
R/W
ET2
Bit5
R/W
ES0
Bit4
R/W
ET1
Bit3
R/W
EX1
Bit2
R/W
ET0
Bit1
R/W
EX0
Reset Value
00000000
SFR Address:
0xA8
Bit0
(bit addressable)
Bit7:
EA: Enable All Interrupts.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask set-
tings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
IEGF0: General Purpose Flag 0.
This is a general purpose flag for use under software control.
ET2: Enable Timer 2 Interrupt.
Bit6:
Bit5:
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt requests generated by the TF2L or TF2H flags.
ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
EX1: Enable External Interrupt 1.
This bit sets the masking of external interrupt 1.
0: Disable external interrupt 1.
1: Enable interrupt requests generated by the /INT1 input.
ET0: Enable Timer 0 Interrupt.
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
EX0: Enable External Interrupt 0.
This bit sets the masking of external interrupt 0.
0: Disable external interrupt 0.
1: Enable interrupt requests generated by the /INT0 input.
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SFR Definition 9.8. IP: Interrupt Priority
R/W
-
R/W
-
R/W
PT2
Bit5
R/W
PS0
Bit4
R/W
PT1
Bit3
R/W
PX1
Bit2
R/W
PT0
Bit1
R/W
PX0
Reset Value
11000000
SFR Address:
0xB8
Bit7
Bit6
Bit0
(bit addressable)
Bits7–6: UNUSED. Read = 11b, Write = don't care.
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PT2: 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.
PS0: 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.
PT1: 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.
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
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SFR Definition 9.9. EIE1: Extended Interrupt Enable 1
R/W
-
R/W
-
R/W
ECP0R
Bit5
R/W
ECP0F
Bit4
R/W
R/W
R/W
R/W
Reset Value
EPCA0 EADC0C EWADC0 ESMB0 00000000
Bit3
Bit7
Bit6
Bit2
Bit1
Bit0
SFR Address:
0xE6
Bits7–6: UNUSED. Read = 00b. Write = don’t care.
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ECP0R: Enable Comparator0 (CP0) Rising Edge Interrupt.
This bit sets the masking of the CP0 Rising Edge interrupt.
0: Disable CP0 Rising Edge interrupt.
1: Enable interrupt requests generated by the CP0RIF flag.
ECP0F: Enable Comparator0 (CP0) Falling Edge Interrupt.
This bit sets the masking of the CP0 Falling Edge interrupt.
0: Disable CP0 Falling Edge interrupt.
1: Enable interrupt requests generated by the CP0FIF flag.
EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
EADC0C: 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.
ESMB0: Enable SMBus Interrupt.
This bit sets the masking of the SMBus interrupt.
0: Disable all SMBus interrupts.
1: Enable interrupt requests generated by the SI flag.
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SFR Definition 9.10. EIP1: Extended Interrupt Priority 1
R/W
-
R/W
-
R/W
PCP0R
Bit5
R/W
PCP0F
Bit4
R/W
R/W
R/W
R/W
Reset Value
PPCA0 PADC0C PWADC0 PSMB0 11000000
Bit3
Bit7
Bit6
Bit2
Bit1
Bit0
SFR Address:
0xF6
Bits7–6: UNUSED. Read = 11b. Write = don’t care.
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PCP0R: Comparator0 (CP0) Rising Interrupt Priority Control.
This bit sets the priority of the CP0 rising-edge interrupt.
0: CP0 rising interrupt set to low priority level.
1: CP0 rising interrupt set to high priority level.
PCP0F: Comparator0 (CP0) Falling Interrupt Priority Control.
This bit sets the priority of the CP0 falling-edge interrupt.
0: CP0 falling interrupt set to low priority level.
1: CP0 falling 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.
PADC0C 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.
PSMB0: SMBus Interrupt Priority Control.
This bit sets the priority of the SMBus interrupt.
0: SMBus interrupt set to low priority level.
1: SMBus interrupt set to high priority level.
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SFR Definition 9.11. IT01CF: INT0/INT1 Configuration
R/W
IN1PL
Bit7
R/W
IN1SL2
Bit6
R/W
IN1SL1
Bit5
R/W
IN1SL0
Bit4
R/W
IN0PL
Bit3
R/W
IN0SL2
Bit2
R/W
IN0SL1
Bit1
R/W
Reset Value
IN0SL0 00000001
Bit0
SFR Address:
0xE4
Note: Refer to SFR Definition 16.1 for INT0/1 edge- or level-sensitive interrupt selection.
Bit7:
IN1PL: /INT1 Polarity
0: /INT1 input is active low.
1: /INT1 input is active high.
Bits6–4: IN1SL2–0: /INT1 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT1. Note that this pin assignment is inde-
pendent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register XBR0).
IN1SL2–0
000
/INT1 Port Pin
P0.0
001
P0.1
010
P0.2
011
P0.3
100
P0.4
101
P0.5
110
P0.6
111
P0.7
Bit3:
IN0PL: /INT0 Polarity
0: /INT0 interrupt is active low.
1: /INT0 interrupt is active high.
Bits2–0: INT0SL2–0: /INT0 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT0. Note that this pin assignment is inde-
pendent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register XBR0).
IN0SL2–0
000
/INT0 Port Pin
P0.0
001
P0.1
010
P0.2
011
P0.3
100
P0.4
101
P0.5
110
P0.6
111
P0.7
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9.4. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all inter-
rupts and timers (except the Missing Clock Detector) are inactive, and the system clock is stopped (analog
peripherals remain in their selected states). Since clocks are running in Idle mode, power consumption is
dependent upon the system clock frequency and the number of peripherals left in active mode before
entering Idle. Stop mode consumes the least power. SFR Definition 9.12 describes the Power Control Reg-
ister (PCON) used to control the CIP-51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital
peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off the oscil-
lators lowers power consumption considerably; however a reset is required to restart the MCU.
9.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes execution. All internal registers and memory maintain their
original data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby 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 “17.3. Watchdog Timer
Mode” on page 151 for more information on the use and configuration of the WDT.
Note: Any instruction that sets the IDLE bit should be immediately followed by an instruction that has 2 or
more opcode bytes. For example:
// in 'C':
PCON |= 0x01;
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 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.
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9.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruc-
tion that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital periph-
erals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral
(including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop
mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal
reset sequence and begins program execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the
MCD timeout.
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 8.1).
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.
Note: It is important to follow the instruction to enter Stop mode with one that does not access any SFRs or
RAM (such as a NOP). This will prevent additional supply current in Stop mode.
SFR Definition 9.12. PCON: Power Control
R/W
GF5
Bit7
R/W
GF4
Bit6
R/W
GF3
Bit5
R/W
GF2
Bit4
R/W
GF1
Bit3
R/W
GF0
Bit2
R/W
STOP
Bit1
R/W
IDLE
Bit0
Reset Value
00000000
SFR Address:
0x87
Bits7–2: GF5–GF0: General Purpose Flags 5–0.
These are general purpose flags for use under software control.
STOP: Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
1: CPU goes into Stop mode (turns off internal oscillator).
Bit1:
Bit0:
IDLE: Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode (shuts off clock to CPU, but clock to Timers, Interrupts, Serial
Ports, and Analog Peripherals are still active).
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NOTES:
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10. 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 VDD Monitor and power-on resets, the RST pin is driven low until the device
exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter-
nal oscillator. Refer to Section “12. Oscillators” on page 91 for information on selecting and configuring
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “17.3. Watchdog Timer Mode” on page 151 details the use of the Watchdog Timer).
Once the system clock source is stable, program execution begins at location 0x0000.
Supply
Monitor
'0'
/RST
Power On
Reset
Comparator 0
(wired-OR)
P0.x
P0.y
+
-
C0RSEF
Missing
Clock
Detector
(one-
shot)
Reset
Funnel
PCA
WDT
(Software Reset)
EN
SWRSF
Illegal OTP
operation
EN
Internal
Oscillator
System
Clock
External
Clock
CIP-51
Microcontroller
Core
EXTCLK
System Reset
Clock Select
Source
Extended Interrupt
Handler
Figure 10.1. Reset Sources
Rev. 0.5
81
C8051T600/1/2/3/4/5
10.1. Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low. An additional delay
occurs before the device is released from reset; the delay decreases as the VDD ramp time increases (VDD
ramp time is defined as how fast VDD ramps from 0 V to 1.8 V). Figure 10.2. plots the power-on and VDD
monitor reset timing. For valid ramp times (less than 1 ms), the power-on reset delay (TPORDelay) is typi-
cally less than 0.3 ms. The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to
be released from reset before VDD reaches the VRST level. If the VDD ramp time in an application will
exceed 1 ms, external circuitry should be used to hold RST low until the VDD supply is within the valid sup-
ply range for the device.
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data mem-
ory is undefined after a power-on reset. The VDD monitor is disabled following a power-on reset.
VDD
TBD
TBD
VRST
TBD
TBD
t
/RST
Logic HIGH
TPORDelay
Logic LOW
VDD
Power-On
Reset
Monitor
Reset
Figure 10.2. Power-On and V Monitor Reset Timing
DD
82
Rev. 0.5
C8051T600/1/2/3/4/5
10.2. Power-Fail Reset/V Monitor
DD
If the power supply monitor is enabled, when a power-down transition or power irregularity causes VDD to
drop below VRST, the power supply monitor will drive the RST pin low and hold the CIP-51 in a reset state
(see Figure 10.2). When VDD returns to a level above VRST, the CIP-51 will be released from the reset
state. Note that even though internal data memory contents are not altered by the power-fail reset, it is
impossible to determine if VDD dropped below the level required for data retention. If the PORSF flag reads
‘1’, the data may no longer be valid. The VDD monitor is disabled after power-on resets; however its
defined state (enabled/disabled) is not altered by any other reset source. For example, if the VDD monitor
is enabled and a software reset is performed, the VDD monitor will still be enabled after the reset. The VDD
monitor is enabled by writing a ‘1’ to the PORSF bit in register RSTSRC. See Figure 10.2 for VDD monitor
timing; note that the reset delay is not incurred after a VDD monitor reset. See Table 10.2 for electrical char-
acteristics of the VDD monitor.
Important Note: Enabling the VDD monitor when it is not already enabled will immediately generate a sys-
tem reset. The device will then return from the reset state with the VDD monitor enabled. Writing a logic
‘1’ to the PORSF flag when the VDD monitor is already enabled does not cause a system reset.
10.3. 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 10.2 for complete RST pin
specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
10.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system
clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a
MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise,
this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables
it. The state of the RST pin is unaffected by a missing clock detector reset.
10.5. 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 a
Comparator0 reset.
10.6. 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 “17.3. Watchdog Timer Mode” on
page 151; 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 a WDT reset.
Rev. 0.5
83
C8051T600/1/2/3/4/5
10.7. OTP Error Reset
If an OTP program read or a write procedure 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 OTP location which is above the user code space
address limit.
An OTP 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.
Table 10.1. User Code Space Address Limits
Device
User Code Space Address Limit
C8051T600/1
C8051T602/3
C8051T604/5
0x1DFF
0x0FFF
0x07FF
The OTPERR bit (RSTSRC.6) is set following any OTP error reset. The state of the RST pin is unaffected
by an OTP error reset.
10.8. 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 a software reset.
84
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 10.1. RSTSRC: Reset Source
R
-
R
R/W
R/W
R
R/W
R/W
R
Reset Value
OTPERR C0RSEF SWRSF WDTRSF MCDRSF PORSF PINRSF Variable
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xEF
Note: For bits that act as both reset source enables (on a write) and reset indicator flags (on a read), read-
modify-write instructions read and modify the source enable only.
Bit7:
Bit6:
UNUSED. Read = 0. Write = don’t care.
OTPERR: OTP Error Indicator.
0: Source of last reset was not an OTP read error.
1: Source of last reset was an OTP read error.
C0RSEF: Comparator0 Reset Enable and Flag.
Write
0: Comparator0 is not a reset source.
1: Comparator0 is a reset source (active-low).
Read
0: Source of last reset was not Comparator0.
1: Source of last reset was Comparator0.
SWRSF: Software Reset Force and Flag.
Write
Bit5:
Bit4:
0: No Effect.
1: Forces a system reset.
Read
0: Source of last reset was not a write to the SWRSF bit.
1: Source of last was a write to the SWRSF bit.
WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
MCDRSF: Missing Clock Detector Flag.
Write:
Bit3:
Bit2:
0: Missing Clock Detector disabled.
1: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected.
Read:
0: Source of last reset was not a Missing Clock Detector timeout.
1: Source of last reset was a Missing Clock Detector timeout.
PORSF: Power-On Reset Force and Flag.
This bit is set anytime a power-on reset occurs. This may be due to a true power-on reset or a
Bit1:
V
monitor reset. In either case, data memory should be considered indeterminate following
DD
the reset. Writing this bit enables/disables the V monitor.
DD
Write:
0: V monitor disabled.
DD
1: V monitor enabled.
DD
Read:
0: Last reset was not a power-on or V monitor reset.
DD
1: Last reset was a power-on or V monitor reset; all other reset flags indeterminate.
DD
Bit0:
PINRSF: HW Pin Reset Flag.
0: Source of last reset was not RST pin.
1: Source of last reset was RST pin.
Rev. 0.5
85
C8051T600/1/2/3/4/5
Table 10.2. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
—
Typ
Max
Units
IOL = 8.5 mA,
RST Output Low Voltage
—
0.6
V
V
VDD = 1.8 to 3.6 V
0.7 x VDD
RST Input High Voltage
RST Input Low Voltage
RST Input Leakage Current
—
—
0.3 x VDD
—
—
RST = 0.0 V
25
40
1
µA
ms
V
V
DD Ramp Time for POR
Ramp from 0 to 1.8 V
—
—
VDD Monitor Threshold (VRST
)
TBD
TBD
TBD
Time from last system clock
rising edge to reset initiation
Missing Clock Detector Timeout
Reset Time Delay
300
—
450
—
600
60
µs
µs
µs
Delay between release of any
reset source and code execu-
tion at location 0x0000
Minimum RST Low Time to
Generate a System Reset
15
—
—
86
Rev. 0.5
C8051T600/1/2/3/4/5
11. One-Time Programmable Read-Only Memory
C8051T600/1/2/3/4/5 devices include 8 kB (C8051T600/1), 4 kB (C8051T602/3), or 2 kB (C8051T604/5) of
on-chip One Time Programmable (OTP) EPROM for program code storage. The EPROM memory can be
programmed via the C2 debug and programming interface when a special programming voltage is applied
to the VPP pin. Table 11.1 shows the EPROM specifications.
Table 11.1. EPROM Electrical Characteristics
Parameter
OTP EPROM Size
Conditions
C8051T600/1
Min
8192*
4096
2048
—
Typ
—
Max
—
Units
Bytes
Bytes
Bytes
µs
OTP EPROM Size
C8051T602/3
C8051T604/5
—
—
OTP EPROM Size
—
—
Write Cycle Time (per Byte)
100
6.5
—
Programming Voltage (VPP
)
6.25
6.75
V
*Note: 512 bytes at location 0x1E00 to 0x1FFF are not available for program storage
11.1. Programming the EPROM Memory
Programming of the OTP 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. Please refer to the “C2 Interface Specification” available at http://www.silabs.com for details
on communicating via the C2 interface. Section “19. C2 Interface” on page 161 has information about
C2 register addresses for the C8051T600/1/2/3/4/5.
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 0x58 to the EPCTL register.
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. Poll the OTPBusy bit using a C2 Address Read command. Note: If OTPError is set at this
time, the write operation failed.
10. 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.
11. Remove program mode (1st step): Write 0x40 to the EPCTL register.
12. Remove the VPP programming Voltage.
13. Remove program mode (2nd step): Write 0x00 to the EPCTL register.
14. Reset the device: Write 0x02 and then 0x00 to the DEVCTL register.
Important Note: There is a finite amount of time which VPP can be applied without damaging the
device, which is cumulative over the life of the device. Refer to Table 2.1 on page 23 for the VPP tim-
ing specification.
Rev. 0.5
87
C8051T600/1/2/3/4/5
11.2. Security Options
The C8051T600/1/2/3/4/5 devices provide security options to prevent unauthorized viewing of proprietary
program code and constants. A security byte stored at location 0x1FFF in EPROM address space can be
used to lock the program memory from being read or written across the C2 interface. The lock byte can
always be read regardless of the security settings. Table 11.2 shows the security byte decoding. See
Figure 11.1 for the program memory map and security byte locations for each device.
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 11.2. Security Byte Decoding
Bits
Description
Write Lock: Clearing any of these bits to logic 0 prevents all code
memory from being written across the C2 interface.
Read Lock: Clearing any of these bits to logic 0 prevents all code
memory from being read across the C2 interface.
7–4
3–0
C8051T600/1
C8051T602/3
C8051T604/5
0x1FFF
0x1FFF
0x1FFE
0x1FFF
0x1FFE
Security Byte
Security Byte
Security Byte
0x1FFE
0x1E00
0x1DFF
Reserved
Reserved
Reserved
0x1000
0x0FFF
7680 Bytes
OTP Memory
4096 Bytes
OTP Memory
0x0800
0x07FF
2048 Bytes
OTP Memory
0x0000
0x0000
0x0000
Figure 11.1. OTP EPROM Program Memory Map
88
Rev. 0.5
C8051T600/1/2/3/4/5
11.3. 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.
11.3.1. Performing 32-bit CRCs on Full EPROM Content
A 32-bit CRC on the enter 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 OTP-
Busy bit in register C2ADD will be set during the CRC operation, and cleared once the operation is com-
plete. 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 per-
formed since the last device reset, a device reset should be initiated before performing a 32-bit CRC oper-
ation.
11.3.2. 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 OTPBusy 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.
Rev. 0.5
89
C8051T600/1/2/3/4/5
NOTES:
90
Rev. 0.5
C8051T600/1/2/3/4/5
12. Oscillators
All C8051T600/1/2/3/4/5 devices include a calibrated, precision internal oscillator and an external clock
input circuit. The external clock input circuitry can be configured to operate from a CMOS clock, an exter-
nal capacitor, or an external RC circuit. The internal oscillator can be enabled/disabled and adjusted using
the OSCICN and OSCICL registers, as shown in Figure 12.1. The system clock can be sourced by the
external clock input circuit, the internal oscillator, or a scaled version of the internal oscillator. The internal
oscillator's electrical specifications are given in Table 12.1 on page 92.
OSCICL
OSCICN
EN
Internal Clock
Generator
n
SYSCLK
Option 1
EXTCLK
Input
Circuit
OSC
EXTCLK
Option 2
EXTCLK
Option 3
VDD
EXTCLK
OSCXCN
Figure 12.1. Oscillator Diagram
12.1. Calibrated Internal Oscillator
All C8051T600/1/2/3/4/5 devices include a calibrated internal oscillator that defaults as the system clock
after a system reset. The oscillator is factory calibrated to obtain a 24.5 MHz frequency at room tempera-
ture, using the OSCICL register.
The controller’s core clock (SYSCLK) may be derived from the 24.5 MHz 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,
producing a 3.0625 MHz system clock.
Rev. 0.5
91
C8051T600/1/2/3/4/5
SFR Definition 12.1. OSCICL: Internal Oscillator Calibration
R/W
-
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
Variable
SFR Address:
0xB3
Bit7
Bit7:
UNUSED. Read = 0. Write = don’t care.
Bits6–0: OSCICL: Internal Oscillator Calibration Register.
This register adjusts the internal oscillator period. The reset value for OSCICL defines the
internal oscillator base frequency. The reset value of this register is factory calibrated to gen-
erate an internal oscillator frequency of 24.5 MHz.
SFR Definition 12.2. OSCICN: Internal Oscillator Control
R/W
-
R/W
-
R/W
-
R
R/W
R/W
R/W
IFCN1
Bit1
R/W
Reset Value
IFRDY
Bit4
CLKSL IOSCEN
Bit3
IFCN0 00010100
Bit0
Bit7
Bit6
Bit5
Bit2
SFR Address:
0xB2
Bits7–5: UNUSED. Read = 000b, Write = don't care.
Bit4:
Bit3:
Bit2:
IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator is not running at programmed frequency.
1: Internal Oscillator is running at programmed frequency.
CLKSL: System Clock Source Select Bit.
0: SYSCLK derived from the Internal Oscillator, and scaled as per the IFCN bits.
1: SYSCLK derived from the External Clock circuit.
IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bits1–0: IFCN1–0: Internal Oscillator Frequency Control Bits.
00: SYSCLK derived from Internal Oscillator divided by 8.
01: SYSCLK derived from Internal Oscillator divided by 4.
10: SYSCLK derived from Internal Oscillator divided by 2.
11: SYSCLK derived from Internal Oscillator divided by 1.
Table 12.1. Internal Oscillator Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Calibrated Internal Oscillator
Frequency
Conditions
Min
Typ
Max Units
TBD
24.5
TBD
—
MHz
µA
Internal Oscillator Supply Current
OSCICN.2 = 1
—
TBD
(from VDD
)
92
Rev. 0.5
C8051T600/1/2/3/4/5
12.2. External Oscillator Circuit
The external oscillator circuit can accept an external CMOS clock, or operate from an external capacitor or
RC circuit applied to the EXTCLK pin (P0.3). To operate in external CMOS mode, the EXTCLK pin should
be configured as a digital input. For capacitor or RC mode, the EXTCLK pin should be configured as an
analog input. See Section “13.2. Port I/O Initialization” on page 99 for details on Port input mode selec-
tion. Whenever an external clock option is used, the Port I/O Crossbar should be configured to skip the
EXTCLK pin. See Section “13.1. Priority Crossbar Decoder” on page 98 for Crossbar configuration
details. Note that the external oscillator control settings should not be changed while running the processor
from an external oscillator source.
12.3. System Clock Selection
The CLKSL bit in register OSCICN selects which oscillator is used as the system clock. CLKSL must be
set to ‘1’ for the system clock to run from an external clock source; however, the external clock may still
clock peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The system
clock may be switched on-the-fly between the internal and external clock sources, so long as the selected
oscillator is enabled and has settled. The internal oscillator requires very little start-up time and may be
enabled and selected as the system clock in the same write to OSCICN. When switching between internal
and external clock sources, the hand-off to the other clock source lasts two clock cycles of the slower
clock.
Rev. 0.5
93
C8051T600/1/2/3/4/5
SFR Definition 12.3. OSCXCN: External Oscillator Control
R
-
R/W
R/W
R/W
R
-
R/W
XFCN2
Bit2
R/W
XFCN1
Bit1
R/W
Reset Value
XOSCMD2 XOSCMD1 XOSCMD0
XFCN0 00000000
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
SFR Address:
0xB1
Bit7:
Unused. Read = 0, Write = don’t care.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100 RC Oscillator Mode with divide by 2 stage.
101: Capacitor Oscillator Mode with divide by 2 stage.
11x: Reserved.
Bit3:
Unused. Read = 0, Write = don't care.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000–111: See table below:
XFCN
K Factor
Approximate Frequency Range
(Capacitor Mode)
000
001
010
011
100
101
110
111
0.87
2.6
7.7
22
65
180
664
1590
f < 25 kHz
25 kHz < f < 50 kHz
50 kHz < f < 100 kHz
100 kHz < f < 200 kHz
200 kHz < f < 400 kHz
400 kHz < f < 800 kHz
800 kHz < f < 1.6 MHz
1.6 MHz < f < 3.2 MHz
Capacitor Mode (Circuit from Figure 12.1, Option 2, XOSCMD = 101)
Choose K Factor (KF) matching the oscillation frequency desired:
KF
C × VDD
--------------------
f =
where
f = frequency of oscillation in MHz
C = capacitor value on the EXTCLK pin in pF
DD = Power Supply on MCU in volts
V
RC Mode (Circuit from Figure 12.1, Option 3, XOSCMD = 100)
Choose XFCN value to match desired frequency range:
1.23 × 1023
---------------------------
f =
R × C
where
f = frequency of oscillation in MHz
C = capacitor value on the EXTCLK pin in pF
R = pullup resistor value in kΩ
94
Rev. 0.5
C8051T600/1/2/3/4/5
12.4. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 12.1, Option 2. The capacitor should be no greater than 100 pF; however, for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and f =
150 kHz:
KF
C × VDD
---------------------
f =
KF
C × 3.0
-----------------
0.150 MHz =
Since a frequency of roughly 150 kHz is desired, select the K Factor from SFR Definition 12.3 as KF = 22:
22
C × 3.0 V
-----------------------
0.150 MHz =
22
----------------------------------------------
C =
0.150 MHz × 3.0 V
C = 48.8 pF
Therefore, the XFCN value to use in this example is 011b and C is approximately 50 pF.
12.5. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 12.1, Option 3. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To 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. If the frequency desired is
100 kHz, let R = 246 k and C = 50 pF:
1.23 × 103
1.23 × 103
------------------------
------------------------
= 100 kHz
f =
=
R × C
246 × 50
Referencing the table in SFR Definition 12.3, the required XFCN setting is 010b.
Rev. 0.5
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NOTES:
96
Rev. 0.5
C8051T600/1/2/3/4/5
13. Port Input/Output
Digital and analog resources are available through a byte-wide digital I/O Port, Port0. Each of the Port pins
can be defined as general-purpose I/O (GPIO), analog input, or assigned to one of the internal digital
resources as shown in Figure 13.3. The designer has complete control over which functions are assigned,
limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the
use of a Priority Crossbar Decoder. The state of a Port I/O pin can always be read in the corresponding
Port latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 13.3 and Figure 13.4). The registers XBR0, XBR1, and XBR2, defined in SFR Definition 13.1, SFR
Definition 13.2, and SFR Definition 13.3 are used to select internal digital functions.
All Port I/Os are 5 V tolerant (refer to Figure 13.2 for the Port cell circuit). The Port I/O cells are configured
as either push-pull or open-drain in the Port0 Output Mode register (P0MDOUT). Complete Electrical
Specifications for Port I/O are given in Table 13.1 on page 104.
XBR0, XBR1,
P0MDOUT,
XBR2 Registers
P0MDIN Registers
Priority
Decoder
2
2
2
Highest
Priority
UART
Digital
Crossbar
SMBus
CP0
Outputs
P0.0
P0.7
P0
I/O
Cells
8
SYSCLK
4
2
PCA
T0, T1
8
Lowest
Priority
Port Latch
P0
(P0.0-P0.7)
Figure 13.1. Port I/O Functional Block Diagram
/WEAK-PULLUP
VDD
VDD
PUSH-PULL
/PORT-OUTENABLE
(WEAK)
PORT
PAD
PORT-OUTPUT
GND
Analog Select
ANALOG INPUT
PORT-INPUT
Figure 13.2. Port I/O Cell Block Diagram
Rev. 0.5
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C8051T600/1/2/3/4/5
13.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 13.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the XBR0 register are set. The XBR0 register allows software to skip Port pins that are to
be used for analog input or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding XBR0 bit should be set. This applies to P0.0 if VREF is enabled, 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 13.3 shows the Crossbar Decoder
priority with no Port pins skipped (XBR0 = 0x00); Figure 13.4 shows the Crossbar Decoder priority with
pins 6 and 2 skipped (XBR0 = 0x44).
P0
SF Signals
PIN I/O
VREF
0
EXTCLK
3
CNVSTR
6 7
1
2
4
5
TX0
RX0
SDA
SCL
CP0
CP0A
SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
0
0
0
0
0
0
0
0
XBR0[0:7]
Port pin potentially available to peripheral
SF Signals
Special Function Signals are not assigned by the crossbar.
When these signals are enabled, the CrossBar must be
manually configured to skip their corresponding port pins.
Figure 13.3. Crossbar Priority Decoder with XBR0 = 0x00
98
Rev. 0.5
C8051T600/1/2/3/4/5
P0
SF Signals
PIN I/O
VREF
0
EXTCLK
3
CNVSTR
6 7
1
2
4
5
TX0
RX0
SDA
SCL
CP0
CP0A
SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
0
0
1
0
0
0
1
0
XBR0[0:7]
Port pin potentially available to peripheral
Port pin skipped by CrossBar
SF Signals
Special Function Signals are not assigned by the crossbar. When
these signals are enabled, the CrossBar must be manually
configured to skip their corresponding port pins.
Figure 13.4. Crossbar Priority Decoder with XBR0 = 0x44
Registers XBR1 and XBR2 are used to assign the digital I/O resources to the physical I/O Port pins. Note
that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and
SCL). Either or both of the UART signals may be selected by the Crossbar. UART0 pin assignments are
fixed for bootloading purposes: when UART TX0 is selected, it is always assigned to P0.4; when UART
RX0 is selected, it is always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized
functions have been assigned. For example, if assigned functions that take the first 3 Port I/O (P0.[2:0]), 5
Port I/O are left for analog or GPIO use.
13.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port0 Input Mode
register (P0MDIN).
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port0 Output
Mode register (P0MDOUT).
Step 3. Set XBR0 to skip any pins selected as analog inputs or special functions.
Step 4. Assign Port pins to desired peripherals.
Step 5. Enable the Crossbar.
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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 pull-up, digital driver, and digital receiver is 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 XBR0). Port input mode is set in the P0MDIN 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 Defini-
tion 13.5 for the P0MDIN register details.
The output driver characteristics of the I/O pins are defined using the Port0 Output Mode register
P0MDOUT (see SFR Definition 13.6). 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 P0MDOUT settings. When the WEAKPUD bit in XBR2 is ‘0’, a weak pull-up is
enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Fur-
thermore, the weak pull-up is turned off on an open-drain output that is driving a ‘0’ to avoid unnecessary
power dissipation.
Registers XBR0, XBR1 and XBR2 must be loaded with the appropriate values to select the digital I/O func-
tions required by the design. Setting the XBARE bit in XBR2 to ‘1’ enables the Crossbar. Until the Crossbar
is enabled, the external pins remain as standard digital inputs (output drivers disabled) regardless of the
XBRn Register settings. For given XBRn Register settings, one can determine the I/O pin-out using the
Priority Decode Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software
will determine the Port I/O pin-assignments based on the XBRn Register settings.
SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0
R/W
-
R/W
XSKP6
Bit6
R/W
XSKP5
Bit5
R/W
XSKP4
Bit4
R/W
XSKP3
Bit3
R/W
XSKP2
Bit2
R/W
XSKP1
Bit1
R/W
Reset Value
XSKP0 00000000
Bit0
Bit7
SFR Address:
0xE1
Bit7:
UNUSED. Read = 0b; Write = don’t care.
Bits6–0: XSKP[6:0]: Crossbar Skip Enable Bits
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as ana-
log inputs (for ADC or Comparator) or used as special functions (VREF input, external oscil-
lator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
100
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1
R/W
R/W
Bit6
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PCA0ME
Bit7
CP0AOEN CP0OEN SYSCKE SMB0OEN URX0EN UTX0EN 00000000
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE2
Bits7–6: PCA0ME: PCA Module I/0 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.
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
CP0AOEN: Comparator0 Asynchronous Output Enable
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin.
CP0OEN: 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.
SMB0OEN: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SDA, SCL routed to Port pins.
URX0EN: UART RX Enable
0: UART RX0 unavailable at Port pin.
1: UART RX0 routed to Port pin P0.5.
UTX0EN: UART TX Output Enable
0: UART TX0 unavailable at Port pin.
1: UART TX0 routed to Port pin P0.4.
Rev. 0.5
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C8051T600/1/2/3/4/5
SFR Definition 13.3. XBR2: Port I/O Crossbar Register 2
R/W
R/W
R/W
-
R/W
-
R/W
-
R/W
T1E
Bit2
R/W
T0E
Bit1
R/W
ECIE
Bit0
Reset Value
00000000
SFR Address:
0xE3
WEAKPUD XBARE
Bit7
Bit6
Bit5
Bit4
Bit3
Bit7:
Bit6:
WEAKPUD: Port I/O Weak Pull-up Disable.
0: Weak Pull-ups enabled (except for Ports whose I/O are configured as push-pull).
1: Weak Pull-ups disabled.
XBARE: Crossbar Enable.
0: Crossbar disabled.
1: Crossbar enabled.
Bits5–3: UNUSED: Read=000b. Write = don’t care.
Bit2:
Bit1:
Bit0:
T1E: 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 Counter Input Enable.
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
13.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for
general purpose I/O. Port0 is accessed through a corresponding special function register (SFR) that is
both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is latched
to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins are
returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the
Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the
execution of the read-modify-write instructions. The read-modify-write instructions when operating on a
Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SET, when the
destination is an individual bit in a Port SFR. For these instructions, the value of the register (not the pin) is
read, modified, and written back to the SFR.
102
Rev. 0.5
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SFR Definition 13.4. P0: Port0
R/W
P0.7
Bit7
R/W
P0.6
Bit6
R/W
P0.5
Bit5
R/W
P0.4
Bit4
R/W
P0.3
Bit3
R/W
P0.2
Bit2
R/W
P0.1
Bit1
R/W
P0.0
Reset Value
11111111
SFR Address:
0x80
Bit0
(bit addressable)
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers
0: Logic Low Output.
1: Logic High Output (open-drain if corresponding P0MDOUT.n bit = 0)
Read - Always reads ‘1’ if selected as analog input in register P0MDIN. Directly reads Port
pin when configured as digital input.
0: P0.n pin is logic low.
1: P0.n pin is logic high.
SFR Definition 13.5. P0MDIN: Port0 Input Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
SFR Address:
0xF1
Bits7–0: Input Configuration Bits for P0.7–P0.0 (respectively)
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P0.n pin is configured as an analog input.
1: Corresponding P0.n pin is configured as a digital input.
SFR Definition 13.6. P0MDOUT: Port0 Output Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xA4
Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in regis-
ter P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push-pull.
(Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless
of the value of P0MDOUT).
Rev. 0.5
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C8051T600/1/2/3/4/5
Table 13.1. Port I/O DC Electrical Characteristics
VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameters
Conditions
IOH = –3 mA, Port I/O push-pull
Min
Typ
—
Max
—
Units
0.8 x VDD
IOH = –10 µA, Port I/O push-pull
—
Output High Voltage
VDD – 0.1
—
—
V
0.7 x VDD
—
IOH = –10 mA, Port I/O push-pull
IOL = 8.5 mA
IOL = 10 µA
—
—
—
0.6
0.1
—
Output Low Voltage
—
V
0.4 x VDD
—
IOL = 25 mA
0.7 x VDD
Input High Voltage
Input Low Voltage
—
—
—
25
—
V
V
0.3 x VDD
—
—
—
Weak Pull-up Off
±1
40
Input Leakage Current
µA
Weak Pull-up On, VIN = 0 V
104
Rev. 0.5
C8051T600/1/2/3/4/5
14. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/10th of the system clock operating as
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 differ-
ent 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. Three SFRs are associated with the SMBus:
SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data
register, used for both transmitting and receiving SMBus data and slave addresses.
SMB0CN
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
FILTER
SCL
SMBUS CONTROL LOGIC
Arbitration
Interrupt
Request
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
SCL
Control
C
R
O
S
S
B
A
R
N
Data Path
Control
SDA
Control
IRQ Generation
Port I/O
SMB0DAT
7 6 5 4 3 2 1 0
SDA
FILTER
N
Figure 14.1. SMBus Block Diagram
Rev. 0.5
105
C8051T600/1/2/3/4/5
14.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification—Version 2.0, Philips Semiconductor.
3. System Management Bus Specification—Version 1.1, SBS Implementers Forum.
14.2. SMBus Configuration
Figure 14.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-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 = 5 V
VDD = 3 V
VDD = 5 V
VDD = 3 V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 14.2. Typical SMBus Configuration
14.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. Note that it is not necessary to specify one
device as the Master in a system; any device that transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 14.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowl-
edge), which is a high SDA during a high SCL.
106
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The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the 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 14.3 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 14.3. SMBus Transaction
14.3.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section “14.3.4. SCL High (SMBus Free) Timeout”
on page 108). In the event that two or more devices attempt to begin a transfer at the same time, an arbi-
tration scheme is employed to force one master to give up the bus. The master devices continue transmit-
ting 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 win-
ning master continues its transmission without interruption; the losing master becomes a slave and
receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device
always wins, and no data is lost.
Rev. 0.5
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14.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
14.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 2 is used to detect SCL low timeouts. Timer 2 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 2 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 2 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout. Timer 2 configuration details can be found
in Section “16.2. Timer 2” on page 139.
14.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation.
14.4. 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 transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See Section “14.5. SMBus Transfer Modes” on page 117 for more details on transmission
sequences.
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Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“14.4.2. SMB0CN Control Register” on page 113; Table 14.4 provides a quick SMB0CN decoding refer-
ence.
SMBus configuration options include:
•
•
•
•
Timeout detection (SCL Low Timeout and/or Bus Free Timeout)
SDA setup and hold time extensions
Slave event enable/disable
Clock source selection
These options are selected in the SMB0CF register, as described in Section “14.4.1. SMBus Configura-
tion Register” on page 110.
Rev. 0.5
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14.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
Table 14.1. SMBus Clock Source Selection
SMBCS1
SMBCS0
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
0
0
1
1
0
1
0
1
The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 14.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “16. Timers” on page 131.
1
---------------------------------------------
THighMin = TLowMin
=
fClockSourceOverflow
Equation 14.1. 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 14.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 14.2.
fClockSourceOverflow
---------------------------------------------
BitRate =
3
Equation 14.2. Typical SMBus Bit Rate
Figure 14.4 shows the typical SCL generation described by Equation 14.2. Notice that THIGH is typically
twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 14.1.
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Timer Source
Overflows
SCL
TLow
THigh
SCL High Timeout
Figure 14.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high.
The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable
after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 14.2 shows the 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 14.2. Minimum SDA Setup and Hold Times
EXTHOLD
Minimum SDA Setup Time
Minimum SDA Hold Time
Tlow - 4 system clocks
0
1
3 system clocks
OR
1 system clock + s/w delay*
11 system clocks
12 system clocks
*Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w
delay occurs between the time SMB0DAT or ACK is written and when SI is cleared.
Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w
delay is zero.
With the SMBTOE bit set, Timer 2 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “14.3.3. SCL Low Timeout” on page 108). The SMBus interface will force Timer 2
to reload while SCL is high, and allow Timer 2 to count when SCL is low. The Timer 2 interrupt service rou-
tine should be used to reset SMBus communication by disabling and re-enabling the SMBus. Timer 2 con-
figuration is described in Section “16.2. Timer 2” on page 139.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 14.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an
interrupt will be generated, and STO will be set).
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SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration
R/W
ENSMB
Bit7
R/W
INH
Bit6
R
R/W
R/W
R/W
R/W
R/W
Reset Value
BUSY EXTHOLD SMBTOE SMBFTE SMBCS1 SMBCS0 00000000
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC1
Bit7:
ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enabled, the interface constantly mon-
itors the SDA and SCL pins.
0: SMBus interface disabled.
1: SMBus interface enabled.
Bit6:
INH: SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events
occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5:
Bit4:
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 14.2.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3:
SMBTOE: SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 2 to
reload while SCL is high and allows Timer 2 to count when SCL goes low. If Timer 2 is con-
figured in split mode (T2SPLIT is set), only the high byte of Timer 2 is held in reload while
SCL is high. Timer 2 should be programmed to generate interrupts at 25 ms, and the Timer
2 interrupt service routine should reset SMBus communication.
SMBFTE: SMBus Free Timeout Detection Enable.
Bit2:
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for
more than 10 SMBus clock source periods.
Bits1–0: SMBCS1–SMBCS0: SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus bit
rate. The selected device should be configured according to Equation 14.1.
SMBCS1 SMBCS0
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
0
0
1
1
0
1
0
1
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14.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 14.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
The STA bit indicates that a START has been detected or generated since the last SMBus interrupt. When
set to ‘1’, the STA bit will cause the SMBus to enter Master mode and generate a START when the bus
becomes free. STA is not cleared by hardware after the START is generated; it must be cleared by soft-
ware.
As a master, writing the STO bit will cause the hardware to generate a STOP condition and end the current
transfer after the next ACK cycle. STO is cleared by hardware after the STOP condition is generated. As a
slave, STO indicates that a STOP condition has been detected since the last SMBus interrupt. STO is also
used in slave mode to manage the transition from slave receiver to slave transmitter; see Section 14.5.4
for details on this procedure.
If STO and STA are both set to ‘1’ (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 14.3 for more details.
Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 14.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 14.4 for SMBus sta-
tus decoding using the SMB0CN register.
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SFR Definition 14.2. SMB0CN: SMBus Control
R
R
R/W
STA
Bit5
R/W
STO
Bit4
R
R
R/W
ACK
Bit1
R/W
Reset Value
00000000
SFR Address:
0xC0
MASTER TXMODE
ACKRQ ARBLOST
SI
Bit0
Bit7
Bit6
Bit3
Bit2
(bit addressable)
Bit7:
MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operating as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
Bit6:
Bit5:
1: SMBus in Transmitter Mode.
STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operating as a master, a START condition is transmitted if the bus is free (If the bus
is not free, the START is transmitted after a STOP is received or a free timeout is detected).
If STA is set by software as an active Master, a repeated START will be generated after the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Start detected.
Bit4:
STO: SMBus Stop Flag.
Write:
As a master, setting this bit to ‘1’ causes a STOP condition to be transmitted after the next
ACK cycle. STO is cleared to ‘0’ by hardware when the STOP is generated.
As a slave, software manages this bit when switching from Slave Receiver to Slave Trans-
mitter mode. See Section 14.5.4 for details.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode).
ACKRQ: SMBus Acknowledge Request.
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK
bit to be written with the correct ACK response value.
ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a
transmitter. A lost arbitration while a slave indicates a bus error condition.
ACK: SMBus Acknowledge Flag.
Bit3:
Bit2:
Bit1:
This bit defines the out-going ACK level and records incoming ACK levels. It should be writ-
ten each time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if
in Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
Bit0:
SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 14.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
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Table 14.3. 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.
• The SMBus interface enters transmitter mode • Arbitration is lost.
(after SMB0DAT is written before the start of • SMB0DAT is not written before the
TXMODE
an SMBus frame).
start of an SMBus frame.
• A START followed by an address byte is
received.
• A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A byte has been received and an ACK
response value is needed.
• Must be cleared by software.
STA
STO
• A pending STOP is generated.
• After each ACK cycle.
ACKRQ
• A repeated START is detected as a MASTER • Each time SI is cleared.
when STA is low (unwanted repeated START).
• SCL is sensed low while attempting to gener-
ate a STOP or repeated START condition.
• SDA is sensed low while transmitting a ‘1’
(excluding ACK bits).
• The incoming ACK value is low (ACKNOWL- • The incoming ACK value is high (NOT
EDGE).
ARBLOST
ACK
ACKNOWLEDGE).
• A START has been generated.
• Lost arbitration.
• Must be cleared by software.
• A byte has been transmitted and an
ACK/NACK received.
• A byte has been received.
• A START or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
SI
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14.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbi-
tration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 14.3. SMB0DAT: SMBus Data
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xC2
Bits7–0: SMB0DAT: SMBus Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial inter-
face 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
one. The serial data in the register remains stable as long as the SI flag is set. When the SI
flag is not set, the system may be in the process of shifting data in/out and the CPU should
not attempt to access this register.
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14.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in
Master Mode until it loses arbitration or generates a STOP. An SMBus interrupt is generated at the end of
all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating
as a receiver, and after the ACK cycle when operating as a transmitter.
14.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates
the START condition and transmits the first byte containing the address of the target slave and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits
one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the
slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will
switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 14.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any
number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK
cycle in this mode.
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
Transmitted by
SLA = Slave Address
SMBus Interface
Figure 14.5. Typical Master Transmitter Sequence
Rev. 0.5
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14.5.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the
START condition and transmits the first byte containing the address of the target slave and the data direc-
tion bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the
slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial
data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write
the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit gen-
erates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last
byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and
a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written
while an active Master Receiver. Figure 14.6 shows a typical Master Receiver sequence. Two received
data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’
interrupts occur before the ACK cycle in this mode.
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
N = NACK
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 14.6. Typical Master Receiver Sequence
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14.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit
(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the
ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received
slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until
the next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver; see Section 14.5.4 for details on
this procedure. Figure 14.7 shows a typical Slave Receiver sequence. Two received data bytes are shown,
though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur
before the ACK cycle in this mode.
Interrupt
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 14.7. Typical Slave Receiver Sequence
Rev. 0.5
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14.5.4. Slave Transmitter Mode
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH
= 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a
slave address and direction bit (READ in this case) is received. Software responds to the received slave
address with an ACK, or ignores the received slave address with a NACK. If the received address is
ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is
acknowledged, software should write data to SMB0DAT to force the SMBus into Slave Transmitter Mode.
The switch from Slave Receiver to Slave Transmitter requires software management. Software should per-
form the steps outlined below only when a valid slave address is received (indicated by the label “RX-to-TX
Steps” in Figure 14.8).
Step 1. Set ACK to ‘1’.
Step 2. Write outgoing data to SMB0DAT.
Step 3. Check SMB0DAT.7; if ‘1’, do not perform steps 4, 6 or 7.
Step 4. Set STO to ‘1’.
Step 5. Clear SI to ‘0’.
Step 6. Poll for TXMODE => ‘1’.
Step 7. Clear STO to ‘0’ (must be done before the next ACK cycle).
The interface enters Slave Transmitter Mode and transmits one or more bytes of data (the above steps are
only required before the first byte of the transfer). After each byte is transmitted, the master sends an
acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If
the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error
condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter
Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will
switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter interrupt.
Figure 14.8 shows a typical Slave Transmitter sequence. Two transmitted data bytes are shown, though
any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the
ACK cycle in this mode.
Perform RX-to-TX
Steps Here
Interrupt
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt
Interrupt
Interrupt
S = START
P = STOP
N = NACK
W = WRITE
Received by SMBus
Interface
Transmitted by
SMBus Interface
SLA = Slave Address
Figure 14.8. Typical Slave Transmitter Sequence
14.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform with the SMBus specification. Highlighted responses are allowed but do not conform
to the SMBus specification.
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Table 14.4. SMBus Status Decoding
Values
Written
Values Read
Current SMbus State
Typical Response Options
A master START was gen- Load slave address + R/W into
1110
1100
0
0
0
0
X
0
1
0
0
0
1
X
X
X
erated.
SMB0DAT.
A master data or address
Set STA to restart transfer.
0 byte was transmitted; NACK
received.
Abort transfer.
Load next data byte into SMB0DAT
End transfer with STOP
0
0
0
1
X
X
End transfer with STOP and start
another transfer.
A master data or address
1 byte was transmitted; ACK
received.
1
1
1
0
X
X
0
0
Send repeated START
Switch to Master Receiver Mode
(clear SI without writing new data
to SMB0DAT).
0
0
X
Acknowledge received byte; Read
SMB0DAT.
0
0
0
1
1
0
Send NACK to indicate last byte,
and send STOP.
Send NACK to indicate last byte,
and send STOP followed by
START.
1
1
0
Send ACK followed by repeated
START.
A master data byte was
X
1
1
0
0
1
0
1000
1
0
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).
0
0
0
0
1
0
Send NACK and switch to Mas-
ter Transmitter Mode (write to
SMB0DAT before clearing SI).
A slave byte was transmit- No action required (expecting
0
0
0
0
0
1
0
1
X
0
0
0
0
0
0
X
X
X
ted; NACK received.
A slave byte was transmit- Load SMB0DAT with next data
ted; ACK received. byte to transmit.
A Slave byte was transmit- No action required (expecting Mas-
STOP condition).
0100
0101
ted; error detected.
ter to end transfer).
A STOP was detected while
X an addressed Slave Trans-
mitter.
No action required (transfer com-
plete).
0
X
0
0
X
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Table 14.4. SMBus Status Decoding (Continued)
Values
Written
Values Read
Current SMbus State
Typical Response Options
Acknowledge received address
(received slave address match,
R/W bit = READ).
0
0
0
0
1
0
Do not acknowledge received
address.
A slave address was
received; ACK requested.
1
0
X
Acknowledge received address,
and switch to transmitter mode
(received slave address match,
R/W bit = WRITE); see Section
14.5.4 for procedure.
0
0
1
Acknowledge received address
(received slave address match,
R/W bit = READ).
0010
0
0
0
0
1
0
Do not acknowledge received
address.
Lost arbitration as master;
X slave address received;
ACK requested.
Acknowledge received address,
and switch to transmitter mode
(received slave address match,
R/W bit = WRITE); see Section
14.5.4 for procedure.
1
1
0
0
1
Reschedule failed transfer; do not
acknowledge received address
1
0
1
0
0
0
0
Lost arbitration while
X attempting a repeated
START.
Abort failed transfer.
X
X
0010
0001
0
1
0
0
1
1
0
1
Reschedule failed transfer.
Lost arbitration while
X
No action required (transfer com-
plete/aborted).
0
0
0
0
0
attempting a STOP.
A STOP was detected while
X an addressed slave
receiver.
No action required (transfer com-
plete).
X
Abort transfer.
0
1
0
0
X
X
Lost arbitration due to a
detected STOP.
X
Reschedule failed transfer.
Acknowledge received byte; Read
SMB0DAT.
0
0
1
A slave byte was received;
ACK requested.
1
1
0
1
X
Do not acknowledge received byte. 0
0
0
0
0
0000
Lost arbitration while trans- Abort failed transfer.
X mitting a data byte as mas-
0
Reschedule failed transfer.
ter.
1
0
0
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15. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “15.1. Enhanced Baud Rate Generation” on page 124). 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. Reading SBUF0
accesses the buffered Receive register; writing SBUF0 accesses 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
SCON0
TI
RI
UART Baud
Rate Generator
Serial
Port
Interrupt
Port I/O
Rx IRQ
Rx Clock
Rx Control
Load
SBUF
Start
Shift
0x1FF
RB8
Input Shift Register
(9 bits)
Load SBUF0
SBUF
(RX Latch)
Read
SBUF
SFR Bus
RX
Crossbar
Figure 15.1. UART0 Block Diagram
Rev. 0.5
123
C8051T600/1/2/3/4/5
15.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 15.2), which is not 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
UART0
Overflow
TX Clock
2
2
TH1
Start
Detected
Overflow
RX Clock
RX Timer
Figure 15.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “16.1.3. Mode 2: 8-bit
Counter/Timer with Auto-Reload” on page 133). The Timer 1 reload value should be set so that over-
flows will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by
one of five sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, or the external oscillator clock / 8.
For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 15.1.
T1CLK
1
------------------------------ --
UartBaudRate =
×
(256 – T1H) 2
Equation 15.1. UART0 Baud Rate
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “16.2. Timer 2” on page 139. A quick
reference for typical baud rates and system clock frequencies is given in Tables 14.1 through 14.6. Note
that the internal oscillator may still generate the system clock when the external oscillator is driving Timer 1
(see Section “16.1. Timer 0 and Timer 1” on page 131 for more details).
124
Rev. 0.5
C8051T600/1/2/3/4/5
15.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown in Figure 15.3.
TX
RS-232
RS-232
LEVEL
XLTR
C8051Fxxx
RX
OR
TX
RX
TX
RX
MCU
C8051Fxxx
Figure 15.3. UART Interconnect Diagram
15.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX pin and received at the RX 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 15.4. 8-Bit UART Timing Diagram
Rev. 0.5
125
C8051T600/1/2/3/4/5
15.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a 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 15.5. 9-Bit UART Timing Diagram
15.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE0 bit (SCON.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic one (RB80 = 1) signifying an
address byte has been received. In the UART interrupt handler, software will compare the received
address with the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0
bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave
their MCE0 bits set and do not generate interrupts on the reception of the following data bytes, thereby
ignoring the data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore
all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
126
Rev. 0.5
C8051T600/1/2/3/4/5
Master
Device
Slave
Device
Slave
Device
Slave
Device
+5V
RX
TX
RX
TX
RX
TX
RX
TX
Figure 15.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 0.5
127
C8051T600/1/2/3/4/5
SFR Definition 15.1. SCON0: Serial Port 0 Control
R/W
S0MODE
Bit7
R/W
-
R/W
MCE0
Bit5
R/W
REN0
Bit4
R/W
TB80
Bit3
R/W
RB80
Bit2
R/W
TI0
Bit1
R/W
RI0
Reset Value
00000000
SFR Address:
0x98
Bit6
Bit0
(bit addressable)
Bit7:
S0MODE: Serial Port 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: Mode 0: 8-bit UART with Variable Baud Rate
1: Mode 1: 9-bit UART with Variable Baud Rate
UNUSED. Read = 1b. Write = don’t care.
MCE0: Multiprocessor Communication Enable.
Bit6:
Bit5:
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.
REN0: Receive Enable.
Bit4:
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3:
Bit2:
Bit1:
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
RB80: Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 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
RI0: Receive Interrupt Flag.
Bit0:
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 soft-
ware.
128
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x99
Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB–LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF0, it goes to the transmit shift register and is held for serial transmis-
sion. Writing a byte to SBUF0 is what initiates the transmission. A read of SBUF0 returns the
contents of the receive latch.
Rev. 0.5
129
C8051T600/1/2/3/4/5
Table 15.1. Timer Settings for Standard Baud Rates Using
the Internal 24.5 MHz Oscillator
Frequency: 24.5 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla- Timer Clock
SCA1–SCA0
(pre-scale
select)*
T1M*
Timer 1
Reload
Value (hex)
tor Divide
Factor
Source
230400
115200
57600
–0.32%
–0.32%
0.15%
106
212
SYSCLK
SYSCLK
XX
XX
XX
01
00
00
10
10
1
1
1
0
0
0
0
0
0xCB
0x96
0x2B
0x96
0xB9
0x96
0x96
0x2B
426
SYSCLK
28800
–0.32%
0.15%
848
SYSCLK/4
SYSCLK/12
SYSCLK/12
SYSCLK/48
SYSCLK/48
14400
1704
2544
10176
20448
9600
–0.32%
–0.32%
0.15%
2400
1200
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 16.1.
130
Rev. 0.5
C8051T600/1/2/3/4/5
16. Timers
Each MCU includes 3 counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and one is a 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 offers 16-bit and split 8-bit timer functionality with auto-reload.
Timer 0 and Timer 1 Modes:
13-bit counter/timer
Timer 2 Modes:
16-bit timer with auto-reload
16-bit counter/timer
8-bit counter/timer with auto-reload
Two 8-bit counter/timers (Timer 0 only)
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 16.3 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 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. Events with a frequency of
up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it
should be held at a given level for at least two full system clock cycles to ensure the level is properly sam-
pled.
16.1. Timer 0 and Timer 1
Each timer is implemented as 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 their status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register
(Section “9.3.5. Interrupt Register Descriptions” on page 73); Timer 1 interrupts can be enabled by
setting the ET1 bit in the IE register (Section 9.3.5). 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.
16.1.1. 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 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are
enabled.
The C/T0 bit (TMOD.2) 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. (See Section “13.1. Priority
Rev. 0.5
131
C8051T600/1/2/3/4/5
Crossbar Decoder” on page 98 for information on selecting and configuring external I/O pins.) Clearing
C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is clocked by the sys-
tem clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock Scale bits in
CKCON (see SFR Definition 16.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
/INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 9.11). Setting GATE0 to ‘1’
allows the timer to be controlled by the external input signal /INT0 (see Section “9.3.5. Interrupt Register
Descriptions” on page 73), facilitating pulse width measurements.
TR0
0
1
1
1
GATE0
/INT0
Counter/Timer
Disabled
X
0
1
1
X
X
0
1
Enabled
Disabled
Enabled
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 /INT1 is used with Timer 1; the /INT1 polarity is defined by bit IN1PL in register IT01CF (see
SFR Definition 9.11).
CKCON
TMOD
IT01CF
G C T T G C T T
I I I I I I I I
T T T T S S
2 2 1 0 C C
MMMM A A
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
H L
1 0
1
0
2 1 0
2 1 0
Pre-scaled Clock
SYSCLK
0
1
0
1
TF1
TR1
TF0
TR0
IE1
IT1
T0
Interrupt
TCLK
TL0
(5 bits)
TH0
(8 bits)
TR0
GATE0
IE0
IT0
Crossbar
IN0PL
XOR
/INT0
Figure 16.1. T0 Mode 0 Block Diagram
132
Rev. 0.5
C8051T600/1/2/3/4/5
16.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The
counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
16.1.3. 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 (TCON.5) 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 (TMOD.3) is logic 0 or when the input signal /INT0
is active as defined by bit IN0PL in register IT01CF (see Section “9.3.2. External Interrupts” on page 71
for details on the external input signals /INT0 and /INT1).
CKCON
TMOD
IT01CF
G C T T G C T T
I I I I I I I I
T T T T S S
2 2 1 0 C C
MMMM A A
A / 1 1 A / 0 0 N N N N N N N N
T T M M T T M M 1 1 1 1 0 0 0 0
E 1 1 0 E 0 1 0 P S S S P S S S
H L
1 0
1
0
L L L L L L L L
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 16.2. T0 Mode 2 Block Diagram
Rev. 0.5
133
C8051T600/1/2/3/4/5
16.1.4. 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
counter/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.
CKCON
TMOD
G C T T G C T T
T T T T S S
2 2 1 0 C C
M M MM A A
A
/ 1 1 A / 0 0
T T M M T T M M
E 1 1 0 E 0 1 0
H L
1 0
1
0
Pre-scaled Clock
SYSCLK
0
1
TH0
(8 bits)
TR1
TF1
TR1
TF0
TR0
IE1
IT1
Interrupt
Interrupt
0
IE0
IT0
1
T0
TL0
(8 bits)
TR0
Crossbar
GATE0
IN0PL
XOR
/INT0
Figure 16.3. T0 Mode 3 Block Diagram
134
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 16.1. TCON: Timer Control
R/W
TF1
Bit7
R/W
TR1
Bit6
R/W
TF0
Bit5
R/W
TR0
Bit4
R/W
IE1
Bit3
R/W
IT1
Bit2
R/W
IE0
Bit1
R/W
IT0
Reset Value
00000000
SFR Address:
0x88
Bit0
(bit addressable)
Bit7:
TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow detected.
1: Timer 1 has overflowed.
Bit6:
Bit5:
TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow detected.
1: Timer 0 has overflowed.
Bit4:
Bit3:
TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
IE1: External Interrupt 1.
This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Inter-
rupt 1 service routine if IT1 = 1. When IT1 = 0, this flag is set to ‘1’ when /INT1 is active as
defined by bit IN1PL in register IT01CF (see SFR Definition 9.11).
IT1: Interrupt 1 Type Select.
Bit2:
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
9.11).
0: /INT1 is level triggered.
1: /INT1 is edge triggered.
Bit1:
Bit0:
IE0: External Interrupt 0.
This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Inter-
rupt 0 service routine if IT0 = 1. When IT0 = 0, this flag is set to ‘1’ when /INT0 is active as
defined by bit IN0PL in register IT01CF (see SFR Definition 9.11).
IT0: 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
9.11).
0: /INT0 is level triggered.
1: /INT0 is edge triggered.
Rev. 0.5
135
C8051T600/1/2/3/4/5
SFR Definition 16.2. TMOD: Timer Mode
R/W
GATE1
Bit7
R/W
C/T1
Bit6
R/W
T1M1
Bit5
R/W
T1M0
Bit4
R/W
GATE0
Bit3
R/W
C/T0
Bit2
R/W
T0M1
Bit1
R/W
T0M0
Bit0
Reset Value
00000000
SFR Address:
0x89
Bit7:
GATE1: Timer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND /INT1 is active as defined by bit IN1PL in regis-
ter IT01CF (see SFR Definition 9.11).
Bit6:
C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external pin (T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
T1M1
T1M0
Mode
0
0
1
1
0
1
0
1
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Timer 1 inactive
Bit3:
Bit2:
GATE0: Timer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND /INT0 is active as defined by bit IN0PL in regis-
ter IT01CF (see SFR Definition 9.11).
C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external pin (T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
T0M1
T0M0
Mode
0
0
1
1
0
1
0
1
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Two 8-bit counter/timers
136
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 16.3. CKCON: Clock Control
R/W
-
R/W
T2MH
Bit6
R/W
T2ML
Bit5
R/W
T1M
Bit4
R/W
T0M
Bit3
R/W
-
R/W
SCA1
Bit1
R/W
SCA0
Bit0
Reset Value
00000000
SFR Address:
0x8E
Bit7
Bit2
Bit7:
Bit6:
UNUSED. Read = 0b, Write = don’t care.
T2MH: Timer 2 High Byte Clock Select
This bit selects the clock supplied to the Timer 2 high byte if Timer 2 is configured in split 8-
bit timer mode. T2MH is ignored if Timer 2 is in any other mode.
0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 high byte uses the system clock.
Bit5:
T2ML: Timer 2 Low Byte Clock Select
This bit 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.
Bit4:
Bit3:
T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Timer 1 uses the system clock.
T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Counter/Timer 0 uses the system clock.
Bit2:
UNUSED. Read = 0b, Write = don’t care.
Bits1–0: SCA1–SCA0: Timer 0/1 Prescale Bits
These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured
to use prescaled clock inputs.
SCA1
SCA0
Prescaled Clock
0
0
1
1
0
1
0
1
System clock divided by 12
System clock divided by 4
System clock divided by 48
External clock divided by 8
Note: External clock divided by 8 is synchronized with the system
clock, and the external clock must be less than or equal to
the system clock to operate in this mode.
Rev. 0.5
137
C8051T600/1/2/3/4/5
SFR Definition 16.4. TL0: Timer 0 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x8A
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0
SFR Definition 16.5. TL1: Timer 1 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x8B
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
SFR Definition 16.6. TH0: Timer 0 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x8C
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 16.7. TH1: Timer 1 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0x8D
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
138
Rev. 0.5
C8051T600/1/2/3/4/5
16.2. 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.
16.2.1. 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 16.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is
set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled
and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L)
overflow from 0xFF to 0x00.
CKCON
T T T T S S
2 2 1 0 C C
T2XCLK
MM M M A A
H L
1 0
To ADC,
SMBus
To SMBus
TMR2H
SYSCLK / 12
0
1
TMR2L
Overflow
0
1
TCLK
TR2
TF2H
TMR2L
Interrupt
External Clock / 8
SYSCLK
TF2L
TF2LEN
T2SPLIT
TR2
T2XCLK
TMR2RLL TMR2RLH
Reload
Figure 16.4. Timer 2 16-Bit Mode Block Diagram
Rev. 0.5
139
C8051T600/1/2/3/4/5
16.2.2. 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 16.5. 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
Note: External clock divided by 8 is synchronized with the system clock, and the external clock must be
less than or equal to the system clock to operate in this mode.
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time
TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is gener-
ated each time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the
TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags
are not cleared by hardware and must be manually cleared by software.
CKCON
T T T T S S
2 2 1 0 C C
T2XCLK
M M M M A A
Reload
TMR2RLH
To SMBus
H L
1 0
SYSCLK / 12
0
1
0
1
External Clock / 8
TCLK
TF2H
TF2L
TF2LEN
TMR2H
Interrupt
TR2
T2SPLIT
TR2
Reload
TMR2RLL
T2XCLK
SYSCLK
1
0
To ADC,
SMBus
TCLK
TMR2L
Figure 16.5. Timer 2 8-Bit Mode Block Diagram
140
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 16.8. TMR2CN: Timer 2 Control
R/W
TF2H
Bit7
R/W
TF2L
Bit6
R/W
TF2LEN
Bit5
R/W
-
R/W
T2SPLIT
Bit3
R/W
TR2
Bit2
R/W
-
R/W
Reset Value
T2XCLK 00000000
Bit4
Bit1
Bit0
SFR Address:
(bit addressable)
0xC8
Bit7:
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.
TF2H is not automatically cleared by hardware and must be cleared by software.
TF2L: Timer 2 Low Byte Overflow Flag
Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF2LEN is set and Timer 2 interrupts are enabled. TF2L
will set when the low byte overflows regardless of the Timer 2 mode. This bit is not automat-
ically cleared by hardware.
Bit6:
Bit5:
TF2LEN: Timer 2 Low Byte Interrupt Enable.
This bit enables/disables Timer 2 Low Byte interrupts. If TF2LEN is set and Timer 2 inter-
rupts are enabled, an interrupt will be generated when the low byte of Timer 2 overflows.
This bit should be cleared when operating Timer 2 in 16-bit mode.
0: Timer 2 Low Byte interrupts disabled.
1: Timer 2 Low Byte interrupts enabled.
Bit4:
Bit3:
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.
Bit2:
TR2: Timer 2 Run Control.
This bit enables/disables Timer 2. In 8-bit mode, this bit enables/disables TMR2H only;
TMR2L is always enabled in this mode.
0: Timer 2 disabled.
1: Timer 2 enabled.
Bit1:
Bit0:
UNUSED. Read = 0b. Write = don’t care.
T2XCLK: 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 external clock selection is the system clock divided by 12.
1: Timer 2 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
Rev. 0.5
141
C8051T600/1/2/3/4/5
SFR Definition 16.9. TMR2RLL: Timer 2 Reload Register Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xCA
Bits 7–0: TMR2RLL: Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2.
SFR Definition 16.10. TMR2RLH: Timer 2 Reload Register High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xCB
Bits 7–0: TMR2RLH: Timer 2 Reload Register High Byte.
The TMR2RLH holds the high byte of the reload value for Timer 2.
SFR Definition 16.11. TMR2L: Timer 2 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xCC
Bits 7–0: TMR2L: Timer 2 Low Byte.
In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8-bit mode,
TMR2L contains the 8-bit low byte timer value.
SFR Definition 16.12. TMR2H Timer 2 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xCD
Bits 7–0: TMR2H: Timer 2 High Byte.
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.
142
Rev. 0.5
C8051T600/1/2/3/4/5
17. Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and three 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “13.1. Priority
Crossbar Decoder” on page 98 for details on configuring the Crossbar). 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 overflow, 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 “17.2. Capture/Compare
Modules” on page 145). 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 basic PCA block diagram is shown in Figure 17.1.
Important Note: The PCA Module 2 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 17.3 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 / WDT
Digital Crossbar
Port I/O
Figure 17.1. PCA Block Diagram
Rev. 0.5
143
C8051T600/1/2/3/4/5
17.1. 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 17.1. Note that in ‘External oscillator
source divided by 8’ mode, the external oscillator source is synchronized with the system clock,
and must have a frequency less than or equal to the system clock.
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 (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 inter-
rupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1). Clearing the CIDL bit in the
PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle mode.
Table 17.1. PCA Timebase Input Options
CPS2
CPS1
CPS0
Timebase
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock divided by 4)
System clock
External oscillator source divided by 8*
*Note: External oscillator source divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
PCA0CN
C
I
D
L
W W C C C E
D D P P P C
T L S S S F
E C 2 1 0
K
C C
F R
C C C
C C C
F F F
2 1 0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
000
001
010
011
100
101
Timer 0 Overflow
ECI
0
Overflow
To PCA Interrupt System
PCA0H
PCA0L
1
SYSCLK
CF
External Clock/8
To PCA Modules
Figure 17.2. PCA Counter/Timer Block Diagram
144
Rev. 0.5
C8051T600/1/2/3/4/5
17.2. 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 system controller. These registers are used to exchange data with a module and configure the module's
mode of operation.
Table 17.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA capture/com-
pare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are rec-
ognized. PCA0 interrupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1. See
Figure 17.3 for details on the PCA interrupt configuration.
Table 17.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT TOG PWM ECCF
Operation Mode
Capture triggered by positive edge
on CEXn
Capture triggered by negative
edge on CEXn
Capture triggered by transition on
CEXn
X
X
X
X
X
X
1
0
1
0
1
1
0
0
0
0
0
0
0
0
0
X
X
X
X
X
X
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
1
1
X
X
X
0
1
1
0
0
0
0
1
1
1
X
X
X
X
X
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
16-Bit Pulse Width Modulator
1
X = Don’t Care
(for n = 0 to 2)
PCA0CPMn
PCA0CN
PCA0MD
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
C C
F R
C C C
C C C
F F F
2 1 0
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
6
n
0
PCA Counter/
Timer Overflow
1
EPCA0
EA
ECCF0
0
1
Interrupt
Priority
Decoder
PCA Module 0
(CCF0)
0
1
0
1
ECCF1
ECCF2
0
1
PCA Module 1
(CCF1)
0
1
PCA Module 2
(CCF2)
Figure 17.3. PCA Interrupt Block Diagram
Rev. 0.5
145
C8051T600/1/2/3/4/5
17.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA counter/
timer and copy 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 and an interrupt request is generated if CCF interrupts are enabled. The CCFn
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service 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 falling-edge caused
the capture.
PCA Interrupt
PCA0CPMn
PCA0CN
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
C C
F R
C C C
C C C
F F F
2 1 0
6
n
x 0
0 0 0
x
PCA0CPLn
PCA0CPHn
0
1
CEXn
Capture
Port I/O
Crossbar
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 17.4. 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.
146
Rev. 0.5
C8051T600/1/2/3/4/5
17.2.2. 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 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
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
W
M
1
6
n
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
PCA0CN
C C C C C
F R
C C C
F F F
2 1 0
PCA0CPLn
PCA0CPHn
x
0 0
0 0
x
0
1
Enable
Match
16-bit Comparator
PCA
Timebase
PCA0L
PCA0H
Figure 17.5. PCA Software Timer Mode Diagram
Rev. 0.5
147
C8051T600/1/2/3/4/5
17.2.3. 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) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-
Speed Output mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
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
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
ENB
1
6
n
x
0 0
0 x
PCA Interrupt
PCA0CN
C C C C C
F R
C C C
F F F
2 1 0
PCA0CPLn
PCA0CPHn
0
1
Enable
Match
16-bit Comparator
TOGn
Toggle
0
CEXn
Crossbar
Port I/O
1
PCA
Timebase
PCA0L
PCA0H
Figure 17.6. PCA High Speed Output Mode Diagram
148
Rev. 0.5
C8051T600/1/2/3/4/5
17.2.4. 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 17.1.
FPCA
----------------------------------------
=
FCEXn
2 × PCA0CPHn
Equation 17.1. Square Wave Frequency Output
Where FPCA is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
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.
Write to
PCA0CPLn
0
ENB
Reset
PCA0CPMn
P
W
M
1
6
n
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
Write to
PCA0CPHn
ENB
PCA0CPLn
8-bit Adder
PCA0CPHn
1
Adder
Enable
TOGn
x
0
0
0
x
Toggle
0
CEXn
8-bit
Comparator
Enable
match
Crossbar
Port I/O
1
PCA Timebase
PCA0L
Figure 17.7. PCA Frequency Output Mode
Rev. 0.5
149
C8051T600/1/2/3/4/5
17.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate a pulse width modulated (PWM) output on its associ-
ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/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 to ‘1’. When the count value in PCA0L overflows, the CEXn output will
be set to ‘0’ (see Figure 17.8). 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. The duty cycle for 8-Bit PWM Mode is given by
Equation 17.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
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)
---------------------------------------------------
DutyCycle =
256
Equation 17.2. 8-Bit PWM Duty Cycle
Using Equation 17.2, 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
PCA0CPHn
PCA0CPLn
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
6
n
0
0
0
x
0
x
SET
CLR
8-bit
Comparator
Enable
match
CEXn
S
R
Q
Q
Crossbar
Port I/O
PCA Timebase
PCA0L
Overflow
Figure 17.8. PCA 8-Bit PWM Mode Diagram
150
Rev. 0.5
C8051T600/1/2/3/4/5
17.2.6. 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 set to ‘1’; when the counter overflows, CEXn is set to ‘0’. 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 synchro-
nize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by Equation 17.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
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)
----------------------------------------------------
DutyCycle =
65536
Equation 17.3. 16-Bit PWM Duty Cycle
Using Equation 17.3, 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
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
PCA0CPHn
PCA0CPLn
6
n
1
0
0
x
0
x
SET
CLR
Enable
match
CEXn
16-bit Comparator
S
R
Q
Q
Crossbar
Port I/O
PCA Timebase
PCA0H
PCA0L
Overflow
Figure 17.9. PCA 16-Bit PWM Mode
17.3. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 2. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH2) 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 2 operates as a watchdog timer (WDT). The Mod-
ule 2 high byte is compared to the PCA counter high byte; the Module 2 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.
Rev. 0.5
151
C8051T600/1/2/3/4/5
17.3.1. 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 2 is forced into software timer mode.
Writes to the module 2 mode register (PCA0CPM2) 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 (CR) will read zero if the WDT is enabled but user
software has not enabled the PCA counter. If a match occurs between PCA0CPH2 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 PCA0CPH2. Upon a PCA0CPH2 write, PCA0H plus the offset held in PCA0CPL2 is loaded
into PCA0CPH2 (See Figure 17.10).
PCA0MD
C
I
D
L
W W C C C E
D D P P P C
T L S S S F
E C 2 1 0
K
PCA0CPH2
8-bit
Comparator
Match
Reset
Enable
PCA0L Overflow
PCA0CPL2
8-bit Adder
PCA0H
Adder
Enable
Write to
PCA0CPH2
Figure 17.10. PCA Module 2 with Watchdog Timer Enabled
Note that the 8-bit offset held in PCA0CPH2 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 offset is then given (in PCA clocks) by Equation 17.4, where PCA0L is the value of the PCA0L register
at the time of the update.
Offset = (256 × PCA0CPL2) + (256 – PCA0L)
Equation 17.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH2 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF2 flag (PCA0CN.2) while the WDT is
enabled.
152
Rev. 0.5
C8051T600/1/2/3/4/5
17.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
•
•
•
•
Disable the WDT by writing a ‘0’ to the WDTE bit.
Select the desired PCA clock source (with the CPS2–CPS0 bits).
Load PCA0CPL2 with the desired WDT update offset value.
Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle
mode).
•
•
Enable the WDT by setting the WDTE bit to ‘1’.
Reload the WDT by writing any value to PCA0CPH2.
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 PCA0CPL2 defaults to 0x00. Using Equation 17.4, this results in a WDT
timeout interval of 3072 system clock cycles. Table 17.3 lists some example timeout intervals for typical
system clocks, assuming SYSCLK / 12 as the PCA clock source.
1
Table 17.3. Watchdog Timer Timeout Intervals
System Clock (Hz)
24,500,000
24,500,000
24,500,000
12,250,000
12,250,000
12,250,000
6,125,000
PCA0CPL2
255
Timeout Interval (ms)
32.1
16.2
4.1
128
32
255
64.2
32.4
8.3
128
32
255
128.4
64.7
16.6
257
6,125,000
128
6,125,000
32
3,062,5002
3,062,5002
3,062,5002
255
128
32
129.5
33.1
Notes:
1. Assumes SYSCLK/12 as the PCA clock source, and a PCA0L value of 0x00 at the update time.
2. Internal reset frequency for SYSCLK (Internal Oscillator/8).
Rev. 0.5
153
C8051T600/1/2/3/4/5
17.4. Register Descriptions for PCA
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 17.1. PCA0CN: PCA Control
R/W
CF
Bit7
R/W
CR
Bit6
R/W
—
R/W
—
R/W
—
R/W
CCF2
Bit2
R/W
CCF1
Bit1
R/W
CCF0
Reset Value
00000000
SFR Address:
0xD8
Bit5
Bit4
Bit3
Bit0
(bit addressable)
Bit7:
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.
Bit6:
CR: PCA Counter/Timer Run Control.
This bit enables/disables the PCA Counter/Timer.
0: PCA Counter/Timer disabled.
1: PCA Counter/Timer enabled.
Bits5–3: UNUSED. Read = 000b, Write = don't care.
Bit2:
Bit1:
Bit0:
CCF2: 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 routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF1: 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 routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF0: 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 routine. This
bit is not automatically cleared by hardware and must be cleared by software.
154
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 17.2. PCA0MD: PCA Mode
R/W
CIDL
Bit7
R/W
WDTE
Bit6
R/W
WDLCK
Bit5
R/W
—
R/W
CPS2
Bit3
R/W
CPS1
Bit2
R/W
CPS0
Bit1
R/W
ECF
Bit0
Reset Value
01000000
SFR Address:
0xD9
Bit4
Bit7:
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.
WDTE: Watchdog Timer Enable
If this bit is set, PCA Module 2 is used as the Watchdog Timer.
0: Watchdog Timer disabled.
Bit6:
Bit5:
1: PCA Module 2 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.
Bit4:
UNUSED. Read = 0b, Write = don't care.
Bits3–1: CPS2–CPS0: PCA Counter/Timer Pulse Select.
These bits select the clock source for the PCA counter
CPS2
CPS1
CPS0
Timebase
System clock divided by 12
System clock divided by 4
0
0
0
0
0
1
0
1
0
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock
divided by 4)
0
1
1
1
1
1
1
0
0
1
1
0
1
0
1
System clock
External clock divided by 8*
Reserved
Reserved
*Note: External oscillator source divided by 8 is synchronized with the system clock.
Bit0:
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 when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to ‘1’, the PCA0MD register cannot be modified. To change the contents of the
PCA0MD register, the Watchdog Timer must first be disabled.
Rev. 0.5
155
C8051T600/1/2/3/4/5
SFR Definition 17.3. PCA0CPMn: PCA Capture/Compare Mode
R/W
R/W
R/W
CAPPn
Bit5
R/W
CAPNn
Bit4
R/W
MATn
Bit3
R/W
TOGn
Bit2
R/W
PWMn
Bit1
R/W
Reset Value
PWM16n ECOMn
ECCFn 00000000
Bit0
Bit7
Bit6
SFR Address:
0xDA, 0xDB,
0xDC
PCA0CPMn Address:
PCA0CPM0 = 0xDA (n = 0)
PCA0CPM1 = 0xDB (n = 1)
PCA0CPM2 = 0xDC (n = 2)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
PWM16n: 16-bit Pulse Width Modulation Enable.
This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA Module n.
0: Disabled.
1: Enabled.
CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA Module n.
0: Disabled.
1: Enabled.
CAPNn: Capture Negative Function Enable.
This bit enables/disables the negative edge capture for PCA Module n.
0: Disabled.
1: Enabled.
MATn: Match Function Enable.
This bit enables/disables the match function for PCA Module n. When enabled, matches of the
PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD regis-
ter to be set to logic 1.
0: Disabled.
1: Enabled.
Bit2:
Bit1:
Bit0:
TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA Module n. 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 operates in Frequency Output
Mode.
0: Disabled.
1: Enabled.
PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA Module n. 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.
0: Disabled.
1: Enabled.
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.
156
Rev. 0.5
C8051T600/1/2/3/4/5
SFR Definition 17.4. PCA0L: PCA Counter/Timer Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xF9
Bits 7–0: PCA0L: PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
SFR Definition 17.5. PCA0H: PCA Counter/Timer High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xFA
Bits 7–0: PCA0H: PCA Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
Rev. 0.5
157
C8051T600/1/2/3/4/5
SFR Definition 17.6. PCA0CPLn: PCA Capture Module Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xFB, 0xE9,
0xEB
PCA0CPLn Address:
PCA0CPL0 = 0xFB (n = 0)
PCA0CPL1 = 0xE9 (n = 1)
PCA0CPL2 = 0xEB (n = 2)
Bits7–0: PCA0CPLn: PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture Module n.
SFR Definition 17.7. PCA0CPHn: PCA Capture Module High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
0xFC, 0xEA,
0xEC
PCA0CPHn Address:
PCA0CPH0 = 0xFC (n = 0)
PCA0CPH1 = 0xEA (n = 1)
PCA0CPH2 = 0xEC(n = 2)
Bits7–0: PCA0CPHn: PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture Module n.
158
Rev. 0.5
C8051T600/1/2/3/4/5
18. Revision Specific Behavior
This chapter contains behavioral differences between C8051T60x "REV C" and behavior as stated in the
data sheet.
These deviations will be resolved in the next revision of the device.
18.1. Revision Identification
The Lot ID Code on the top side of the device package can be used for decoding device revision informa-
tion. On C8051T60x devices the revision letter is the first letter of the Lot ID Code.
Figure 18.1 and Figure 18.2 show how to find the Lot ID Code on the top side of the device package.
C8051T600
CNZWFA
0648
This first character identifies
the Silicon Revision
Figure 18.1. Device Package - SOIC 14
T600
CNZW
648+
This first character identifies
the Silicon Revision
Figure 18.2. Device Package - QFN 10
Rev. 0.5
159
C8051T600/1/2/3/4/5
18.2. SAR Clock Maximum
The maximum SAR clock for "REV C" devices is slower than specified in the data sheet.
On "REV C" devices, the maximum SAR clock for full-performance operation is 4 MHz. If the SAR clock is
operated faster than 4 MHz on "REV C" devices, there will be degradation to SNR and linearity perfor-
mance of the ADC.
This issue will be corrected for "REV D" and later devices.
18.3. V Monitor Oscillation
DD
On "REV C" devices, when the VDD Supply Monitor is enabled, the device may go into and come back out
of reset very quickly when the supply is very close to the supply monitor's reset threshold. This will cause
the /RST line on the device to pulse low and high accordingly, and may affect systems which are connect-
ing /RST to other devices as well.
This issue will be corrected for "REV D" and later devices.
160
Rev. 0.5
C8051T600/1/2/3/4/5
19. C2 Interface
C8051T600/1/2/3/4/5 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.
19.1. 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 19.1. C2ADD: C2 Address
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
The C2ADD register is accessed via the C2 interface to select the target Data register for
C2 Data Read and Data Write commands, and to report status information. Address register
writes select a register, while address register reads return status information.
Bits7–0: Write: Select target Data Read or Data Write register location:
Address
0x00
0x01
Description
Selects the Device ID Register (read only)
Selects the Revision ID Register (read only)
Selects the C2 Device Control Register
Selects the C2 EPROM Programming Control Register
Selects the C2 EPROM Data Register
Selects the C2 EPROM Address High Byte Register
Selects the C2 EPROM Address Low Byte Register
Selects the CRC0 Register
Selects the CRC1 Register
Selects the CRC2 Register
Selects the CRC3 Register
Selects the Port0 SFR
0x02
0xDF
0xBF
0xAF
0xAE
0xA9
0xAA
0xAB
0xAC
0x80
0xF1
0xA4
Selects the Port0 Input Mode SFR
Selects the Port0 Output Mode SFR
Bit7:
Bit6:
Read: OTPBusy. A ‘1’ indicates that the hardware is performing a write, read, or CRC oper-
ation.
Read: OTPError. A ‘1’ indicates that the most recent OTP operation failed.
Bits5-0: Read: Don’t Care.
Rev. 0.5
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C8051T600/1/2/3/4/5
C2 Register Definition 19.2. DEVICEID: C2 Device ID
Reset Value
00010000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0x00
This read-only register returns the 8-bit device ID: 0x10.
C2 Register Definition 19.3. REVID: C2 Revision ID
Reset Value
Variable
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0x01
This read-only register returns the 8-bit revision ID: For example, Revision A = 0x00.
C2 Register Definition 19.4. DEVCTL: C2 Device State
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0x02
Bits7–0 DEVSTATE: Device Control Register
This register is used to halt the device for EPROM operations via the C2 interface. Refer to
the OTP chapter for more information.
C2 Register Definition 19.5. EPCTL: C2 EPROM Programming Control
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xDF
Bits7–0 EPCTL: EPROM Programming Control Register
This register is used to enable EPROM programming via the C2 interface. Refer to the OTP
chapter for more information.
162
Rev. 0.5
C8051T600/1/2/3/4/5
C2 Register Definition 19.6. EPDAT: C2 EPROM Data
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xBF
Bits7–0: EPDAT: C2 EPROM Data Register
This register is used to pass EPROM data during C2 EPROM operations.
C2 Register Definition 19.7. EPADDRH: C2 EPROM Address High Byte
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xAF
Bits7–0: EPADDRH: C2 EPROM Address High Byte Register
This register is used to set the EPROM address location during C2 EPROM operations.
C2 Register Definition 19.8. EPADDRL: C2 EPROM Address Low Byte
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xAE
Bits7–0: EPADDRL: C2 EPROM Address Low Byte Register
This register is used to set the EPROM address location during C2 EPROM operations.
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C2 Register Definition 19.9. CRC0: CRC Byte 0
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xA9
Bits7–0: CRC Byte 0.
A write to this register initiates a 16-bit CRC of one 256-byte block of EPROM memory. 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 “11.3. Program Memory CRC”
on page 89.
C2 Register Definition 19.10. CRC1: CRC Byte 1
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xAB
Bits7–0: CRC Byte 1.
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 “11.3. Program Memory CRC” on page 89.
C2 Register Definition 19.11. CRC2: CRC Byte 2
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xAC
Bits7–0: CRC Byte 2. See Section “11.3. Program Memory CRC” on page 89.
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C2 Register Definition 19.12. CRC3: CRC Byte 3
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
C2ADD:
0xAD
Bits7–0: CRC Byte 3. See Section “11.3. Program Memory CRC” on page 89.
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19.2. 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 (nor-
mally P0.7) 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 produc-
tion boards. A typical isolation configuration is shown in Figure 19.1.
/Reset (a)
Input (b)
C2CK (/RST)
C2D (P0.7)
Output (c)
C2 Interface Master
Figure 19.1. Typical C2 Pin Sharing
The configuration in Figure 19.1 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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