2.0 V, 32/16 kB Flash, smaRTClock, 12-bit ADC
C8051F410/1/2/3
Rev. 1.1 11/08 Copyright © 2008 by Silicon Laboratories C8051F41x
Analog Peripherals
-12-Bit ADC
•±1 LSB INL; no missing codes
•Programmable throughput up to 200 ksps
•Up to 24 external inputs
•Data dependent windowed interrupt generator
•Built-in temperature sensor (±3 °C)
-
Two 12-Bit Current Mode DACs
-Two Comparators
•Programmable hysteresis and response time
•Configurable as wake-up or reset source
-POR/Brownout Detector
-Voltage Reference—1.5, 2.2 V (programmable)
On-Chip Debug
-On-chip debug circuitry facilitates full-speed, non-
intrusive in-system debug (No emulator required)
-Provides breakpoints, single stepping
-Inspect/modify memory and registers
-Complete development kit
Supply Voltage 2.0 to 5.25 V
-Built-in LDO regulator: 2.1 or 2.5 V
High Speed 8051 μC Core
-Pipelined instruction architecture; executes 70% of
instructions in 1 or 2 system clocks
-Up to 50 MIPS throughput with
50 MHz system clock
-Expanded interrupt handler
Memory
-2304 bytes internal data RAM (256 + 2048)
-32/16 kB Flash; In-system programmable in
512 byte sectors
-64 bytes battery-backed RAM (smaRTClock)
Digital Peripherals
-24 port I/O; push-pull or open-drain, up to 5.25 V
tolerance
-Hardware SMBus™ (I2C™ Compatible), SPI™, and
UART serial ports available concurrently
-Four general purpose 16-bit counter/timers
-Programmable 16-bit counter/timer array with six
capture/compare modules, WDT
-Hardware smaRTClock operates down to 1 V with
64 bytes battery-backed RAM and backup voltage
regulator
Clock Sources
-Internal oscillators: 24.5 MHz 2% accuracy supports
UART operation; clock multiplier up to 50 MHz
-External oscillator: Crystal, RC, C, or Clock
(1 or 2 pin modes)
-smaRTClock oscillator: 32 kHz Crystal or
self-resonant oscillator
-Can switch between clock sources on-the-fly
32-Pin LQFP or 28-Pin 5 x 5 QFN
Temperature Range: –40 to +85 °C
C8051F410/1/2/3
2 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 3
Table of Contents
1. System Overview.................................................................................................... 19
1.1. CIP-51™ Microcontroller................................................................................... 25
1.1.1. Fully 8051 Compatible Instruction Set...................................................... 25
1.1.2. Improved Throughput............................................................................... 25
1.1.3. Additional Features .................................................................................. 25
1.2. On-Chip Debug Circuitry................................................................................... 26
1.3. On-Chip Memory............................................................................................... 27
1.4. Operating Modes .............................................................................................. 28
1.5. 12-Bit Analog to Digital Converter..................................................................... 29
1.6. Two 12-bit Current-Mode DACs........................................................................ 29
1.7. Programmable Comparators............................................................................. 30
1.8. Cyclic Redundancy Check Unit......................................................................... 31
1.9. Voltage Regulator............................................................................................. 31
1.10.Serial Ports....................................................................................................... 31
1.11.smaRTClock (Real Time Clock)....................................................................... 32
1.12.Port Input/Output.............................................................................................. 33
1.13.Programmable Counter Array........................................................................... 34
2. Absolute Maximum Ratings .................................................................................. 35
3. Global DC Electrical Characteristics.................................................................... 36
4. Pinout and Package Definitions............................................................................ 41
5. 12-Bit ADC (ADC0).................................................................................................. 51
5.1. Analog Multiplexer ............................................................................................ 51
5.2. Temperature Sensor......................................................................................... 52
5.3. ADC0 Operation................................................................................................ 52
5.3.1. Starting a Conversion............................................................................... 53
5.3.2. Tracking Modes........................................................................................ 53
5.3.3. Timing....................................................................................................... 54
5.3.4. Burst Mode............................................................................................... 56
5.3.5. Output Conversion Code.......................................................................... 57
5.3.6. Settling Time Requirements..................................................................... 58
5.4. Programmable Window Detector...................................................................... 63
5.4.1. Window Detector In Single-Ended Mode ................................................. 66
6. 12-Bit Current Mode DACs (IDA0 and IDA1)........................................................ 69
6.1. IDAC Output Scheduling................................................................................... 69
6.1.1. Update Output On-Demand ..................................................................... 69
6.1.2. Update Output Based on Timer Overflow ................................................ 70
6.1.3. Update Output Based on CNVSTR Edge................................................. 70
6.2. IDAC Output Mapping....................................................................................... 70
6.3. IDAC External Pin Connections........................................................................ 73
7. Voltage Reference.................................................................................................. 77
8. Voltage Regulator (REG0)...................................................................................... 81
9. Comparators ......................................................................................................... 83
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10.CIP-51 Microcontroller........................................................................................... 93
10.1.Instruction Set................................................................................................... 94
10.1.1.Instruction and CPU Timing..................................................................... 94
10.1.2.MOVX Instruction and Program Memory................................................. 95
10.2.Register Descriptions ....................................................................................... 98
10.3.Power Management Modes............................................................................ 101
10.3.1.Idle Mode ............................................................................................... 102
10.3.2.Stop Mode.............................................................................................. 102
10.3.3.Suspend Mode....................................................................................... 102
11.Memory Organization and SFRs......................................................................... 103
11.1.Program Memory............................................................................................ 103
11.2.Data Memory.................................................................................................. 104
11.3.General Purpose Registers............................................................................ 104
11.4.Bit Addressable Locations.............................................................................. 104
11.5.Stack............................................................................................................... 104
11.6.Special Function Registers............................................................................. 105
12.Interrupt Handler ............ ...................................................................................... 110
12.1.MCU Interrupt Sources and Vectors............................................................... 110
12.2.Interrupt Priorities........................................................................................... 110
12.3.Interrupt Latency............................................................................................. 110
12.4.Interrupt Register Descriptions....................................................................... 112
12.5.External Interrupts.......................................................................................... 117
13.Prefetch Engine.................................................................................................... 119
14.Cyclic Redundancy Check Unit (CRC0) ............................................................. 121
14.1.16-bit CRC Algorithm...................................................................................... 121
14.2.32-bit CRC Algorithm...................................................................................... 123
14.3.Preparing for a CRC Calculation.................................................................... 124
14.4.Performing a CRC Calculation ....................................................................... 124
14.5.Accessing the CRC0 Result........................................................................... 124
14.6.CRC0 Bit Reverse Feature............................................................................. 124
15.Reset Sources....................................................................................................... 127
15.1.Power-On Reset............................................................................................. 128
15.2.Power-Fail Reset / VDD Monitor .................................................................... 129
15.3.External Reset................................................................................................ 130
15.4.Missing Clock Detector Reset ........................................................................ 130
15.5.Comparator0 Reset........................................................................................ 130
15.6.PCA Watchdog Timer Reset .......................................................................... 131
15.7.Flash Error Reset ........................................................................................... 131
15.8.smaRTClock (Real Time Clock) Reset........................................................... 132
15.9.Software Reset............................................................................................... 132
16.Flash Memory ....................................................................................................... 135
16.1.Programming The Flash Memory................................................................... 135
16.1.1.Flash Lock and Key Functions............................................................... 135
16.1.2.Flash Erase Procedure .......................................................................... 135
16.1.3.Flash Write Procedure ........................................................................... 136
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16.2.Non-volatile Data Storage .............................................................................. 137
16.3.Security Options............................................................................................. 137
16.4.Flash Write and Erase Guidelines.................................................................. 139
16.4.1.VDD Maintenance and the VDD Monitor ............................................... 139
16.4.2.16.4.2 PSWE Maintenance.................................................................... 140
16.4.3.System Clock......................................................................................... 140
16.5.Flash Read Timing ......................................................................................... 142
17.External RAM........................................................................................................ 145
18.Port Input/Output.................................................................................................. 147
18.1.Priority Crossbar Decoder.............................................................................. 149
18.2.Port I/O Initialization ....................................................................................... 151
18.3.General Purpose Port I/O............................................................................... 154
19.Oscillators............................................................................................................. 165
19.1.Programmable Internal Oscillator................................................................... 165
19.1.1.Internal Oscillator Suspend Mode.......................................................... 166
19.2.External Oscillator Drive Circuit...................................................................... 168
19.2.1.Clocking Timers Directly Through the External Oscillator...................... 168
19.2.2.External Crystal Example....................................................................... 168
19.2.3.External RC Example............................................................................. 170
19.2.4.External Capacitor Example................................................................... 170
19.3.Clock Multiplier............................................................................................... 172
19.4.System Clock Selection.................................................................................. 174
20.smaRTClock (Real Time Clock)........................................................................... 177
20.1.smaRTClock Interface.................................................................................... 178
20.1.1.smaRTClock Lock and Key Functions................................................... 178
20.1.2.Using RTC0ADR and RTC0DAT to Access
smaRTClock Internal Registers............................................................. 178
20.1.3.smaRTClock Interface Autoread Feature............................................... 178
20.1.4.RTC0ADR Autoincrement Feature......................................................... 179
20.2.smaRTClock Clocking Sources...................................................................... 182
20.2.1.Using the smaRTClock Oscillator in Crystal Mode ................................ 182
20.2.2.Using the smaRTClock Oscillator in Self-Oscillate Mode ...................... 182
20.2.3.Automatic Gain Control (Crystal Mode Only)......................................... 183
20.2.4.smaRTClock Bias Doubling ................................................................... 183
20.2.5.smaRTClock Missing Clock Detector..................................................... 183
20.3.smaRTClock Timer and Alarm Function......................................................... 185
20.3.1.Setting and Reading the smaRTClock Timer Value............................... 185
20.3.2.Setting a smaRTClock Alarm................................................................. 186
20.4.Backup Regulator and RAM........................................................................... 187
21.SMBus ................................................................................................................... 191
21.1.Supporting Documents................................................................................... 192
21.2.SMBus Configuration...................................................................................... 192
21.3.SMBus Operation........................................................................................... 192
21.3.1.Arbitration............................................................................................... 193
21.3.2.Clock Low Extension.............................................................................. 193
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21.3.3.SCL Low Timeout................................................................................... 194
21.3.4.SCL High (SMBus Free) Timeout .......................................................... 194
21.4.Using the SMBus............................................................................................ 194
21.4.1.SMBus Configuration Register............................................................... 195
21.4.2.SMB0CN Control Register..................................................................... 198
21.4.3.Data Register......................................................................................... 201
21.5.SMBus Transfer Modes.................................................................................. 201
21.5.1.Master Transmitter Mode....................................................................... 201
21.5.2.Master Receiver Mode........................................................................... 202
21.5.3.Slave Receiver Mode............................................................................. 203
21.5.4.Slave Transmitter Mode......................................................................... 204
21.6.SMBus Status Decoding................................................................................. 204
22.UART0.................................................................................................................... 207
22.1.Enhanced Baud Rate Generation................................................................... 208
22.2.Operational Modes......................................................................................... 209
22.2.1.8-Bit UART............................................................................................. 209
22.2.2.9-Bit UART............................................................................................. 210
22.3.Multiprocessor Communications .................................................................... 210
23.Enhanced Serial Peripheral Interface (SPI0)...................................................... 217
23.1.Signal Descriptions......................................................................................... 218
23.1.1.Master Out, Slave In (MOSI).................................................................. 218
23.1.2.Master In, Slave Out (MISO).................................................................. 218
23.1.3.Serial Clock (SCK)................................................................................. 218
23.1.4.Slave Select (NSS) ................................................................................ 218
23.2.SPI0 Master Mode Operation......................................................................... 219
23.3.SPI0 Slave Mode Operation........................................................................... 220
23.4.SPI0 Interrupt Sources................................................................................... 221
23.5.Serial Clock Timing......................................................................................... 221
23.6.SPI Special Function Registers...................................................................... 222
24.Timers.................................................................................................................... 231
24.1.Timer 0 and Timer 1....................................................................................... 231
24.1.1.Mode 0: 13-bit Counter/Timer................................................................ 231
24.1.2.Mode 1: 16-bit Counter/Timer................................................................ 233
24.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 233
24.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 234
24.2.Timer 2 ........................................................................................................... 239
24.2.1.16-bit Timer with Auto-Reload................................................................ 239
24.2.2.8-bit Timers with Auto-Reload................................................................ 240
24.2.3.External/smaRTClock Capture Mode..................................................... 241
24.3.Timer 3 ........................................................................................................... 244
24.3.1.16-bit Timer with Auto-Reload................................................................ 244
24.3.2.8-bit Timers with Auto-Reload................................................................ 245
24.3.3.External/smaRTClock Capture Mode..................................................... 246
25.Programmable Counter Array (PCA0)................................................................ 249
25.1.PCA Counter/Timer........................................................................................ 250
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Rev. 1.1 7
25.2.Capture/Compare Modules ............................................................................ 251
25.2.1.Edge-triggered Capture Mode................................................................ 252
25.2.2.Software Timer (Compare) Mode........................................................... 253
25.2.3.High Speed Output Mode....................................................................... 254
25.2.4.Frequency Output Mode ........................................................................ 255
25.2.5.8-Bit Pulse Width Modulator Mode......................................................... 256
25.2.6.16-Bit Pulse Width Modulator Mode....................................................... 257
25.3.Watchdog Timer Mode................................................................................... 257
25.3.1.Watchdog Timer Operation.................................................................... 258
25.3.2.Watchdog Timer Usage ......................................................................... 259
25.4.Register Descriptions for PCA........................................................................ 261
26.C2 Interface........................................................................................................... 265
26.1.C2 Interface Registers.................................................................................... 265
26.2.C2 Pin Sharing ............................................................................................... 267
C8051F410/1/2/3
8 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 9
List of Figures
1. System Overview
Figure 1.1. C8051F410 Block Diagram.................................................................... 21
Figure 1.2. C8051F411 Block Diagram.................................................................... 22
Figure 1.3. C8051F412 Block Diagram.................................................................... 23
Figure 1.4. C8051F413 Block Diagram.................................................................... 24
Figure 1.5. Development/In-System Debug Diagram............................................... 26
Figure 1.6. Memory Map.......................................................................................... 27
Figure 1.7. 12-Bit ADC Block Diagram..................................................................... 29
Figure 1.8. IDAC Block Diagram.............................................................................. 30
Figure 1.9. Comparators Block Diagram.................................................................. 31
Figure 1.10. smaRTClock Block Diagram ................................................................ 32
Figure 1.11. Port I/O Functional Block Diagram....................................................... 33
Figure 1.12. PCA Block Diagram.............................................................................. 34
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. LQFP-32 Pinout Diagram (Top View) .................................................... 44
Figure 4.2. QFN-28 Pinout Diagram (Top View)...................................................... 45
Figure 4.3. LQFP-32 Package Diagram................................................................... 46
Figure 4.4. LQFP-32 Recommended PCB Land Pattern......................................... 47
Figure 4.5. QFN-28 Package Drawing..................................................................... 48
Figure 4.6. QFN-28 Recommended PCB Land Pattern........................................... 49
5. 12-Bit ADC (ADC0)
Figure 5.1. ADC0 Functional Block Diagram............................................................ 51
Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 52
Figure 5.3. ADC0 Tracking Modes........................................................................... 54
Figure 5.4. 12-Bit ADC Tracking Mode Example ..................................................... 55
Figure 5.5. 12-Bit ADC Burst Mode Example with Repeat Count Set to 4............... 56
Figure 5.6. ADC0 Equivalent Input Circuits.............................................................. 58
Figure 5.7. ADC Window Compare Example: Right-Justified Single-Ended Data... 66
Figure 5.8. ADC Window Compare Example: Left-Justified Single-Ended Data ..... 66
6. 12-Bit Current Mode DACs (IDA0 and IDA1)
Figure 6.1. IDAC Functional Block Diagram............................................................. 69
Figure 6.2. IDAC Data Word Mapping...................................................................... 70
Figure 6.3. IDAC Pin Connections ........................................................................... 74
7. Voltage Reference
Figure 7.1. Voltage Reference Functional Block Diagram ....................................... 77
8. Voltage Regulator (REG0)
Figure 8.1. External Capacitors for Voltage Regulator Input/Output........................ 81
Figure 8.2. External Capacitors for Voltage Regulator Input/Output........................ 81
9. Comparators
Figure 9.1. Comparator0 Functional Block Diagram................................................ 83
Figure 9.2. Comparator1 Functional Block Diagram................................................ 84
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10 Rev. 1.1
Figure 9.3. Comparator Hysteresis Plot................................................................... 85
10.CIP-51 Microcontroller
Figure 10.1. CIP-51 Block Diagram.......................................................................... 93
11.Memory Organization and SFRs
Figure 11.1. Memory Map ...................................................................................... 103
12.Interrupt Handler
13.Prefetch Engine
14.Cyclic Redundancy Check Unit (CRC0)
Figure 14.1. CRC0 Block Diagram......................................................................... 121
Figure 14.2. Bit Reverse Register .......................................................................... 124
15.Reset Sources
Figure 15.1. Reset Sources.................................................................................... 127
Figure 15.2. Power-On and VDD Monitor Reset Timing ........................................ 128
16.Flash Memory
Figure 16.1. Flash Program Memory Map.............................................................. 137
17.External RAM
18.Port Input/Output
Figure 18.1. Port I/O Functional Block Diagram..................................................... 147
Figure 18.2. Port I/O Cell Block Diagram ............................................................... 148
Figure 18.3. Crossbar Priority Decoder with No Pins Skipped............................... 149
Figure 18.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 150
Figure 18.5. Port 0 Input Overdrive Current Range................................................ 152
19.Oscillators
Figure 19.1. Oscillator Diagram.............................................................................. 165
Figure 19.2. 32.768 kHz External Crystal Example................................................ 169
Figure 19.3. Example Clock Multiplier Output........................................................ 172
20.smaRTClock (Real Time Clock)
Figure 20.1. smaRTClock Block Diagram .............................................................. 177
21.SMBus
Figure 21.1. SMBus Block Diagram ....................................................................... 191
Figure 21.2. Typical SMBus Configuration............................................................. 192
Figure 21.3. SMBus Transaction............................................................................ 193
Figure 21.4. Typical SMBus SCL Generation......................................................... 196
Figure 21.5. Typical Master Transmitter Sequence................................................ 202
Figure 21.6. Typical Master Receiver Sequence.................................................... 202
Figure 21.7. Typical Slave Receiver Sequence...................................................... 203
Figure 21.8. Typical Slave Transmitter Sequence.................................................. 204
22.UART0
Figure 22.1. UART0 Block Diagram....................................................................... 207
Figure 22.2. UART0 Baud Rate Logic.................................................................... 208
Figure 22.3. UART Interconnect Diagram.............................................................. 209
Figure 22.4. 8-Bit UART Timing Diagram............................................................... 209
Figure 22.5. 9-Bit UART Timing Diagram............................................................... 210
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram.......................... 211
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Rev. 1.1 11
23.Enhanced Serial Peripheral Interface (SPI0)
Figure 23.1. SPI Block Diagram............................................................................. 217
Figure 23.2. Multiple-Master Mode Connection Diagram....................................... 220
Figure 23.3. 3-Wire Single Master and Slave Mode Connection Diagram............. 220
Figure 23.4. 4-Wire Single Master and Slave Mode Connection Diagram............. 220
Figure 23.5. Data/Clock Timing Relationship......................................................... 222
Figure 23.6. SPI Master Timing (CKPHA = 0)........................................................ 227
Figure 23.7. SPI Master Timing (CKPHA = 1)........................................................ 227
Figure 23.8. SPI Slave Timing (CKPHA = 0).......................................................... 228
Figure 23.9. SPI Slave Timing (CKPHA = 1).......................................................... 228
24.Timers
Figure 24.1. T0 Mode 0 Block Diagram.................................................................. 232
Figure 24.2. T0 Mode 2 Block Diagram.................................................................. 233
Figure 24.3. T0 Mode 3 Block Diagram.................................................................. 234
Figure 24.4. Timer 2 16-Bit Mode Block Diagram .................................................. 239
Figure 24.5. Timer 2 8-Bit Mode Block Diagram .................................................... 240
Figure 24.6. Timer 2 Capture Mode Block Diagram............................................... 241
Figure 24.7. Timer 3 16-Bit Mode Block Diagram .................................................. 244
Figure 24.8. Timer 3 8-Bit Mode Block Diagram .................................................... 245
Figure 24.9. Timer 3 Capture Mode Block Diagram............................................... 246
25.Programmable Counter Array (PCA0)
Figure 25.1. PCA Block Diagram............................................................................ 249
Figure 25.2. PCA Counter/Timer Block Diagram.................................................... 250
Figure 25.3. PCA Interrupt Block Diagram............................................................. 251
Figure 25.4. PCA Capture Mode Diagram.............................................................. 252
Figure 25.5. PCA Software Timer Mode Diagram.................................................. 253
Figure 25.6. PCA High-Speed Output Mode Diagram............................................ 254
Figure 25.7. PCA Frequency Output Mode............................................................ 255
Figure 25.8. PCA 8-Bit PWM Mode Diagram......................................................... 256
Figure 25.9. PCA 16-Bit PWM Mode...................................................................... 257
Figure 25.10. PCA Module 5 with Watchdog Timer Enabled................................. 258
26.C2 Interface
Figure 26.1. Typical C2 Pin Sharing....................................................................... 267
C8051F410/1/2/3
12 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 13
List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 20
Table 1.2. Operating Modes Summary .................................................................... 28
2. Absolute Maximum Ratings
Table 2.1.Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3. Global DC Electrical Characteristics
Table 3.1.Global DC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 3.2. Index to Electrical Characteristics Tables ............................................... 39
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F41x .......................................................... 41
Table 4.2. LQFP-32 Package Dimensions .............................................................. 46
Table 4.3. LQFP-32 PCB Land Pattern Dimensions ............................................... 47
Table 4.4. QFN-28 Package Dimensions ................................................................ 48
Table 4.5. QFN-28 PCB Land Pattern Dimensions ................................................. 49
5. 12-Bit ADC (ADC0)
Table 5.1. ADC0 Examples of Right- and Left-Justified Samples ........................... 57
Table 5.2. ADC0 Repeat Count Examples at Various Input Voltages ..................... 57
Table 5.3.ADC0 Electrical Characteristics (VDD = 2.5 V, VREF = 2.2 V) . . . . . . . . 67
Table 5.4.ADC0 Electrical Characteristics (VDD = 2.1 V, VREF = 1.5 V) . . . . . . . . 68
6. 12-Bit Current Mode DACs (IDA0 and IDA1)
Table 6.1.IDAC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
7. Voltage Reference
Table 7.1.Voltage Reference Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 79
8. Voltage Regulator (REG0)
Table 8.1.Voltage Regulator Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . 82
9. Comparators
Table 9.1.Comparator Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 92
10.CIP-51 Microcontroller
Table 10.1. CIP-51 Instruction Set Summary .......................................................... 95
11.Memory Organization and SFRs
Table 11.1. Special Function Register (SFR) Memory Map .................................. 105
Table 11.2. Special Function Registers ................................................................. 106
12.Interrupt Handler
Table 12.1. Interrupt Summary .............................................................................. 111
13.Prefetch Engine
14.Cyclic Redundancy Check Unit (CRC0)
Table 14.1. Example 16-bit CRC Outputs ............................................................. 122
Table 14.2. Example 32-bit CRC Outputs ............................................................. 124
15.Reset Sources
Table 15.1.Reset Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
16.Flash Memory
Table 16.1. Flash Security Summary .................................................................... 138
Table 16.2.Flash Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
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14 Rev. 1.1
17.External RAM
18.Port Input/Output
Table 18.1.Port I/O DC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . 163
19.Oscillators
Table 19.1.Oscillator Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 175
20.smaRTClock (Real Time Clock)
Table 20.1. smaRTClock Internal Registers .......................................................... 179
21.SMBus
Table 21.1. SMBus Clock Source Selection .......................................................... 195
Table 21.2. Minimum SDA Setup and Hold Times ................................................ 196
Table 21.3. Sources for Hardware Changes to SMB0CN ..................................... 200
Table 21.4. SMBus Status Decoding ..................................................................... 205
22.UART0
Table 22.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator ............................................................... 214
Table 22.2. Timer Settings for Standard Baud Rates
Using an External 25.0 MHz Oscillator ............................................... 214
Table 22.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator ......................................... 215
Table 22.4. Timer Settings for Standard Baud Rates
Using an External 18.432 MHz Oscillator ........................................... 215
Table 22.5. Timer Settings for Standard Baud Rates
Using an External 11.0592 MHz Oscillator ......................................... 216
Table 22.6. Timer Settings for Standard Baud Rates
Using an External 3.6864 MHz Oscillator ........................................... 216
23.Enhanced Serial Peripheral Interface (SPI0)
Table 23.1.SPI Slave Timing Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
24.Timers
25.Programmable Counter Array (PCA0)
Table 25.1. PCA Timebase Input Options ............................................................. 250
Table 25.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 251
Table 25.3. Watchdog Timer Timeout Intervals ..................................................... 260
26.C2 Interface
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Rev. 1.1 15
List of Registers
SFR Definition 5.1. ADC0MX: ADC0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . 59
SFR Definition 5.2. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
SFR Definition 5.3. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 61
SFR Definition 5.4. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
SFR Definition 5.5. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
SFR Definition 5.6. ADC0TK: ADC0 Tracking Mode Select . . . . . . . . . . . . . . . . . . . . 63
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 64
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 64
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 65
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 65
SFR Definition 6.1. IDA0CN: IDA0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
SFR Definition 6.2. IDA0H: IDA0 Data High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
SFR Definition 6.3. IDA0L: IDA0 Data Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 6.4. IDA1CN: IDA1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 6.5. IDA1H: IDA0 Data High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 6.6. IDA1L: IDA1 Data Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SFR Definition 7.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
SFR Definition 8.1. REG0CN: Regulator Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 9.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 87
SFR Definition 9.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 88
SFR Definition 9.4. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 89
SFR Definition 9.5. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 90
SFR Definition 9.6. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
SFR Definition 10.1. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 10.2. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 10.3. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 10.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
SFR Definition 10.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
SFR Definition 10.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
SFR Definition 10.7. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 12.1. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 12.2. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
SFR Definition 12.3. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . 114
SFR Definition 12.4. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . 115
SFR Definition 12.5. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 12.6. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . . 116
SFR Definition 12.7. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . 118
SFR Definition 13.1. PFE0CN: Prefetch Engine Control . . . . . . . . . . . . . . . . . . . . . . 119
SFR Definition 14.1. CRC0CN: CRC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
SFR Definition 14.2. CRC0IN: CRC0 Data Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
SFR Definition 14.3. CRC0DAT: CRC0 Data Output . . . . . . . . . . . . . . . . . . . . . . . . . 126
SFR Definition 14.4. CRC0FLIP: CRC0 Bit Flip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
C8051F410/1/2/3
16 Rev. 1.1
SFR Definition 15.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . 130
SFR Definition 15.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
SFR Definition 16.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 141
SFR Definition 16.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
SFR Definition 16.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 16.4. ONESHOT: Flash Oneshot Period . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 17.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 145
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 18.3. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 18.4. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 18.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 18.6. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 18.7. P0MAT: Port0 Match . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 18.8. P0MASK: Port0 Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 18.9. P0ODEN: Port0 Overdrive Mode . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 18.10. P1: Port1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
SFR Definition 18.11. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
SFR Definition 18.12. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 159
SFR Definition 18.13. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
SFR Definition 18.14. P1MAT: Port1 Match . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
SFR Definition 18.15. P1MASK: Port1 Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
SFR Definition 18.16. P2: Port2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
SFR Definition 18.17. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
SFR Definition 18.18. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 162
SFR Definition 18.19. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
SFR Definition 19.1. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 167
SFR Definition 19.2. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 167
SFR Definition 19.3. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 171
SFR Definition 19.4. CLKMUL: Clock Multiplier Control . . . . . . . . . . . . . . . . . . . . . . . 173
SFR Definition 19.5. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
SFR Definition 20.1. RTC0KEY: smaRTClock Lock and Key . . . . . . . . . . . . . . . . . . . 180
SFR Definition 20.2. RTC0ADR: smaRTClock Address . . . . . . . . . . . . . . . . . . . . . . 181
SFR Definition 20.3. RTC0DAT: smaRTClock Data . . . . . . . . . . . . . . . . . . . . . . . . . 182
Internal Register Definition 20.4. RTC0CN: smaRTClock Control . . . . . . . . . . . . . . . 184
Internal Register Definition 20.5. RTC0XCN: smaRTClock Oscillator Control . . . . . . 185
Internal Register Definition 20.6. CAPTUREn: smaRTClock Timer Capture . . . . . . . 186
Internal Register Definition 20.7. ALARMn: smaRTClock Alarm . . . . . . . . . . . . . . . . 187
Internal Register Definition 20.8. RAMADDR: smaRTClock Backup RAM Address . . 187
Internal Register Definition 20.9. RAMDATA: smaRTClock Backup RAM Data . . . . . 188
SFR Definition 21.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 197
SFR Definition 21.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
SFR Definition 21.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
SFR Definition 22.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 212
SFR Definition 22.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 213
C8051F410/1/2/3
Rev. 1.1 17
SFR Definition 23.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 223
SFR Definition 23.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
SFR Definition 23.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
SFR Definition 23.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
SFR Definition 24.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
SFR Definition 24.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
SFR Definition 24.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
SFR Definition 24.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
SFR Definition 24.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
SFR Definition 24.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
SFR Definition 24.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
SFR Definition 24.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 24.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 243
SFR Definition 24.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 243
SFR Definition 24.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
SFR Definition 24.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
SFR Definition 24.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
SFR Definition 24.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 248
SFR Definition 24.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 248
SFR Definition 24.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 24.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 25.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
SFR Definition 25.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
SFR Definition 25.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 263
SFR Definition 25.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 264
SFR Definition 25.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 264
SFR Definition 25.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 264
SFR Definition 25.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 264
C2 Register Definition 26.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
C2 Register Definition 26.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 265
C2 Register Definition 26.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 266
C2 Register Definition 26.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 266
C2 Register Definition 26.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 266
C8051F410/1/2/3
18 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 19
1. System Overview
C8051F41x devices are fully in tegrated, low po wer, mixed-signal system-on-a -chip MCUs. Highlighted fea-
tures are listed below. Refer to Table 1.1 for specific product feature selection.
• High-speed pipelined 8051-compatible microcontroller core (up to 50 MIPS)
• In-system, full-speed, non-intrusive debug interface (on-chip)
• True 12-bit 200 ksps ADC with analog multiplexer and 24 analog inputs
• Two 12-bit Current Output DACs
• Precision programmable 24.5 MHz internal oscillator
• Up to 32 kB bytes of on-chip Flash memory
• 2304 bytes of on-chip RAM
• SMBus/I2C, Enhanced UART, and SPI serial interfaces implemented in hardware
• Four general-purpo se 16 - bit tim er s
• Programmable Counter/Timer Array (PCA) with six capture/compare modules and Watchdog Timer
function
• Hardware smaRTClock (Real Time Clock) operates d own to 1 V with 64 bytes of Backup RAM and a
Backup Voltage Regulator
• Hardware CRC Engine
• On-chip Power-On Reset, VDD Monitor, and Temperature Sensor
• On-chip Voltage Comparators
• Up to 24 Port I/O
With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F41x devices
are truly standalone system-on-a-chip solutions. The Flash memory can be reprogrammed even in-circuit,
providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software
has complete control of all peripherals, and may individually shut down any or all peripherals for power
savings.
The on-chip Silicon Laboratories 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in the final application. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system programming
and debugging without occupying package pins.
Each device is specified for 2.0-to-2.75 V operation (supply voltage can be up to 5.25 V using on-chip reg-
ulator) over the industrial temperature range (–45 to +85 °C). The C8051F41x are available in 28-pin QFN
(also referred to as MLP or MLF) or 32-pin LQFP packages.
C8051F410/1/2/3
20 Rev. 1.1
Table 1.1. Product Selection Guide
Ordering Part Number
MIPS (Peak)
Flash Memory
RAM
Calibrated Internal 24.5 MHz Oscillator
Clock Multiplier
SMBus/I2C
SPI
UART
Timers (16-bit)
Programmable Counter Array
Port I/Os
12-bit ADC ±1 LSB INL
smaRTClock (Real Time Clock)
Two 12-bit Current Output DACs
Internal Voltage Reference
Temperature Sensor
Analog Comparators
Lead-Free (RoHS compliant)
Package
C8051F410-GQ 50 32 kB 2368
4
24
LQFP-32
C8051F411-GM 50 32 kB 2368
4
20
QFN-28
C8051F412-GQ 50 16 kB 2368
4
24
LQFP-32
C8051F413-GM 50 16 kB 2368
4
20
QFN-28
C8051F410/1/2/3
Rev. 1.1 21
Figure 1.1. C8051F410 Block Diagram
UART
32 kB
FLASH
256 B
SRAM
POR
SFR Bus
8
0
5
1
C
o
r
e
x16
Reset
/RST/C2CK
External
Oscillator
Circuit
Debug HW
Brown-
Out
P
0
D
r
v
2 kB
XRAM
XTAL1
XTAL2
P0.0/IDAC0
P0.1/IDAC1
P0.2
P0.3
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
SPI
VDD
C
R
O
S
S
B
A
R
P
1
D
r
v
P1.0/XTAL1
P1.1/XTAL2
P1.2/VREF
P1.3
P1.4
P1.5
P1.6
P1.7
Port 0
Latch
SMBus
Timer
0,1,2,3
Port 1
Latch
24.5 MHz
2% Oscillator
P
2
D
r
v
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7/C2D
12-bit
200 ksps
ADC
A
M
U
X
AIN0-AIN23
VDD
CP1 +
-
Temp
CP0 +
-
C2D
Port 2
Latch
PCA x6 /
WDT
32 KHz
Oscillator
GND
VREF
smaRTCloc k
State
Machine
VRTC-BACKUP
12-bit
IDAC0 IDAC0
smaRTClock Alarm
smaRTClock Block
(to smarRTClock Block)
(to rest of chip)
Battery Switch-Over Circuit
(VDD >= VRTC-BACKUP)
Clock
Mult.
XTAL3
XTAL4
VREG
VREGIN VIO
12-bit
IDAC1 IDAC1
64B RAM
CRC
Engine
C8051F410/1/2/3
22 Rev. 1.1
Figure 1.2. C8051F411 Block Diagram
UART
32 kB
FLASH
256 B
SRAM
POR
SFR Bus
8
0
5
1
C
o
r
e
x16
Reset
/RST/C2CK
External
Oscillator
Circuit
Debug HW
Brown-
Out
P
0
D
r
v
2 kB
XRAM
XTAL1
XTAL2
P0.0/IDAC0
P0.1/IDAC1
P0.2
P0.3
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
SPI
VDD
C
R
O
S
S
B
A
R
P
1
D
r
v
P1.0/XTAL1
P1.1/XTAL2
P1.2/VREF
P1.3
P1.4
P1.5
P1.6
P1.7
Port 0
Latch
SMBus
Timer
0,1,2,3
Port 1
Latch
24.5 MHz
2% Oscillator
P
2
D
r
v
P2.0
P2.1
P2.2
P2.7/C2D
12-bit
200 ksps
ADC
A
M
U
X
AIN0-AIN20
VDD
CP1 +
-
Temp
CP0 +
-
C2D
Port 2
Latch
PCA x6 /
WDT
32 KHz
Oscillator
GND
VREF
smaRTC lock
State
Machine
VRTC-BACKUP
12-bit
IDAC0 IDAC0
smaRTClock Alarm
smaRTClock Block
(to smaRTClock Block)
(to rest of chip)
Battery Switch-Over Circuit
(VDD >= VRTC-BACKUP)
Clock
Mult.
XTAL3
XTAL4
VREG
VREGIN VIO
12-bit
IDAC1 IDAC1
64B RAM
CRC
Engine
C8051F410/1/2/3
Rev. 1.1 23
Figure 1.3. C8051F412 Block Diagram
UART
16 kB
FLASH
256 B
SRAM
POR
SFR Bus
8
0
5
1
C
o
r
e
x16
Reset
/RST/C2CK
External
Oscillator
Circuit
Debug HW
Brown-
Out
P
0
D
r
v
2 kB
XRAM
XTAL1
XTAL2
P0.0/IDAC0
P0.1/IDAC1
P0.2
P0.3
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
SPI
VDD
C
R
O
S
S
B
A
R
P
1
D
r
v
P1.0/XTAL1
P1.1/XTAL2
P1.2/VREF
P1.3
P1.4
P1.5
P1.6
P1.7
Port 0
Latch
SMBus
Timer
0,1,2,3
Port 1
Latch
24.5 MH z
2% Oscillator
P
2
D
r
v
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7/C2D
12-bit
200 ksps
ADC
A
M
U
X
AIN0-AIN23
VDD
CP1 +
-
Temp
CP0 +
-
C2D
Port 2
Latch
PCA x6 /
WDT
32 KHz
Oscillator
GND
VREF
smaRT Clock
State
Machine
VRTC-BACKUP
12-bit
IDAC0 IDAC0
smaRTClock Alarm
smaRTClock Block
(to smaRTClocl Block)
(to rest of chip)
Batt ery Sw itc h -O v e r C ircuit
(VDD >= VRTC-BACKUP)
Clock
Mult.
XTAL3
XTAL4
VREG
VREGIN VIO
12-bit
IDAC1 IDAC1
64B RAM
CRC
Engine
C8051F410/1/2/3
24 Rev. 1.1
Figure 1.4. C8051F413 Block Diagram
UART
16 kB
FLASH
256 B
SRAM
POR
SFR Bus
8
0
5
1
C
o
r
e
x16
Reset
/RST/C2CK
External
Oscillator
Circuit
Debug HW
Brown-
Out
P
0
D
r
v
2 kB
XRAM
XTAL1
XTAL2
P0.0/IDAC0
P0.1/IDAC1
P0.2
P0.3
P0.4/TX
P0.5/RX
P0.6/CNVST
P0.7
SPI
VDD
C
R
O
S
S
B
A
R
P
1
D
r
v
P1.0/XTAL1
P1.1/XTAL2
P1.2/VREF
P1.3
P1.4
P1.5
P1.6
P1.7
Port 0
Latch
SMBus
Timer
0,1,2,3
Port 1
Latch
24.5 MHz
2% Oscillator
P
2
D
r
v
P2.0
P2.1
P2.2
P2.7/C2D
12-bit
200 ksps
ADC
A
M
U
X
AIN0-AIN20
VDD
CP1 +
-
Temp
CP0 +
-
C2D
Port 2
Latch
PCA x6 /
WDT
32 KHz
Oscillator
GND
VREF
smaRTClock
State
Machine
VRTC-BACKUP
12-bit
IDAC0 IDAC0
smaRTClock Alarm
smaRTClock Block
(to smaRTClock Block)
(to rest of chip)
Battery Switch-Over Circuit
(VDD >= VRTC-BACKUP)
Clock
Mult.
XTAL3
XTAL4
VREG
VREGIN VIO
12-bit
IDAC1 IDAC1
64B RAM
CRC
Engine
C8051F410/1/2/3
Rev. 1.1 25
1.1. CIP-51™ Microcontroller
1.1.1. Fully 8051 Compatible Instruction Set
The C8051F41x devices use Silicon Laboratories’ proprietary CIP-51 microcontroller core. The CIP-51 is
fully compatible with the MCS-51™ instruction set. Standard 803x/805x assemblers and compilers can be
used to develop sof twar e. The C805 1F41x family ha s a su perset of all the peripherals included with a st an-
dard 8052.
1.1.2. Improved Throughput
The CIP-51 emplo ys a p ipeli ned architectu re tha t grea tly increases it s instr uction throug hput over the st an-
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-to-24 MHz. By contrast, the CIP-
51 core executes 70% of it s instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 50 MHz, it has a peak thro ughput o f 50 MIPS. The CIP-51 ha s a
total of 109 instructions. The t able below shows th e tota l number of instructions that require ea ch execution
time.
1.1.3. Additional Features
The C8051F41x SoC family includes several key enhancements to the CIP-51 core and peripherals to
improve performance and ease of use in end applications.
An extended interrupt handler allows the numerous analog and digital peripherals to operate inde-
pendently of the controller core and interrupt the controller only when necessary. By requiring less inter-
vention from the microcontroller core, an interrupt-driven system is more efficient and allows for easier
implementation of multi-tasking, real-time systems.
Eight reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor, a Watchdog
Timer, a Missing Clock Detector, a voltage level detection from Comparator0, a smaRTClock alarm or
missing smaRTClock clock detector reset, a forced software reset, an external reset pin, and an illegal
Flash access protection circuit. Each reset source except for the POR, Reset Input Pin, or Flash error may
be disabled by the user in software. The WDT may be permanently enabled in software after a power-on
reset during MCU initialization.
The internal oscillator is factory calibrated to 24.5 MHz ±2%. An external oscillator drive circuit is also
included, allowing an e xternal cryst al, ceramic resonator, capacitor, RC, or CMOS clock source to generate
the system clock. A clock multiplier allows for operation at up to 50 MHz. The dedicated smaRTClock oscil-
lator can be extremely useful in low power applications, allowing the system to maintain accurate time
while the MCU is not powered, or its internal oscillator is suspended. The MCU can be reset or have its
oscillator awakened using the smaRTClock alarm function.
Clocks to Execute 1 2 2/4 33/5 4 5 4/6 6 8
Number of Instructions 26 50 510 752121
C8051F410/1/2/3
26 Rev. 1.1
1.2. On-Chip Debug Circuitry
The C8051F41x devices include on-chip Silicon Laboratories 2-Wire (C2) debug circuitry that provides
non-intrusive, full speed, in-circuit debugging of the production part installed in the end application.
Silicon Laboratories’ debugging system supports inspection and modification of memory and registers,
breakpoints, and s ingle stepping. No ad ditional target RAM, progr am memory, timers, or communications
channels are require d. All th e d igital and analog pe ripherals are functional and work correctly while debug-
ging. All the periphera ls (except for the ADC and SMBus) are st alled when the MCU is h alted, during single
stepping, or at a brea kp o i nt in or de r to keep the m synchronized.
The C8051F410DK development kit provides all the hardware and sof tware necessary to develop applica-
tion code and perform in-circuit debugging with the C8051F41x MCUs. The kit includes software with a
developer's studio and debugger, a USB debug adapter, a target application board with the associated
MCU installed , and the re quired cables an d wall-mount p ower supply. The development kit requires a com-
puter with Windows®98 SE or later installed. As shown in Figure 1.5, the PC is connected to the USB
debug adapter. A six-inch ribbon cable connects the USB debug adapter to the user's application board,
picking up the two C2 pins and GND.
The Silicon Laboratories IDE interface is a vastly superior developing and debugging configuration, com-
pared to standard MCU emulators that use on-board "ICE Chips" and require the MCU in the application
board to be socketed. Silicon Laboratories’ debug paradigm increases ease of use and preserves the per-
formance of the precision analog peripherals.
Figure 1.5. Development/In-System Debug Diagram
TARGET PCB
USB
Debug
Adapter
VDD GND
C2 (x2), GN D
WINDOWS 98 SE or later
Silic o n La bora to r ie s I nt e g ra t e d
Development Environm ent
C8051F41x
C8051F410/1/2/3
Rev. 1.1 27
1.3. 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 du al-mappe d. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128-byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
Program memory consists of 32 kB (‘F410/1) or 16 kB (‘F412/3) of Flash. This memory may be repro-
grammed in-system in 512 byte sectors and requires no special off-chip programming voltage.
Figure 1.6. Memory Map
PROGRAM/DATA MEMORY
(Flash)
(Direct and Indirect
Addressing)
0x00
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
0x80
0xFF Special Function
Register's
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
0x1F
0x20
0x2F Bit Addressable
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 2048 Bytes
(accessible using M OVX
instruction)
0x0000
0x07FF
Same 2048 by tes a s from
0x0000 to 0x07FF, wrappe d
on 2048-byte boundaries
0x0800
0xFFFF
32 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x0000
RESERVED
0x7E00
0x7DFF
‘F410/1
16 kB Flash
(In -Sy stem
Programmable in 512
Byte Sectors)
0x0000
RESERVED
0x4000
0x3FFF
‘F412/3
C8051F410/1/2/3
28 Rev. 1.1
1.4. Operating Modes
The C8051F41x devices have four operating modes: Active (Normal), Idle, Suspend, and Stop. Active
mode occurs during normal operation when the oscillator and peripherals are active. Idle mode halts the
CPU while leaving the peripherals and internal clocks active. Suspend mode halts SYSCLK until a waken -
ing event occurs, which also halts all peripherals using SYSCLK. In Stop mode, the CPU is halted, all inter-
rupts and timers are inactive, and the internal oscillator is stopped. The various operating modes are
described in Table 1.2 below:
See Section “10.3. Power Management Modes” on page 101 for Idle and Stop mode details. See Sec-
tion “19.1.1. Internal Oscillator Suspend Mode” on page 166 for more information on Suspend mode.
Table 1.2. Operating Modes Summary
Properties Power
Consumption How
Entered? How Exited?
Active
• SYSCLK active
• CPU active (accessing Flash)
• Peripherals active or inactive
depending on user settings
• smaRTClock active or inactive
Full — —
Idle
• SYSCLK active
• CPU inactive (not accessing
Flash)
• Peripherals active or inactive
depending on user settings
• smaRTClock active or inactive
Less than Full IDLE
(PCON.0) Any enabled
interrupt or
device reset
Suspend
• SYSCLK inactive
• CPU inactive (not accessing
Flash)
• Peripherals enabled (but not
operating) or disabl ed depend-
ing on user settings
• smaRTClock active or inactive
Low SUSPEND
(OSCICN.5) Wakening
event or exter-
nal/MCD reset
Stop
• SYSCLK inactive
• CPU inactive (not accessing
Flash)
• Digital peripherals inactive;
analog peripherals enabled
(but not operating ) or disabled
depending on user settings
• smaRTClock inactive
Very low STOP
(PCON.1) External or
MCD reset
C8051F410/1/2/3
Rev. 1.1 29
1.5. 12-Bit Analog to Digital Converter
The C8051F41x devices include an on-chip 12-bit SAR ADC with a 27-channel single-ended input multi-
plexer and a maximum throughput of 200 ksps. The ADC system includes a configurable analog multi-
plexer that selects the positive ADC input, which is measured with respect to GND. Ports 0–2 ar e availabl e
as ADC inputs; additionally, the on - chip Temperature Sen so r ou tp ut an d th e co re su p ply vo ltage (VDD) are
available as ADC inputs. User firmware may shut down the ADC or use it in Burst Mode to save power.
Conversions can be started in four ways: a software command, an overflow of Timer 2 or 3, or an external
convert start signal. This flexibility allows the start of conversion to be triggered by software events, a peri-
odic signal (timer overflows), or external HW signals. Conversion completions are indicated by a status bit
and an interrupt (if enabled) and occur after 1, 4, 8, or 16 samples have been accumulated by a hardware
accumulator. The resulting data word is latched into the ADC data SFRs upon completion of a conversion.
When the system clock is slow, Burst Mode allows ADC0 to automatically wake from a low power shut-
down state, acquire and accumulate samples, then re-enter the low power shutdown state without CPU
intervention.
Window comp are registers for the ADC dat a can be co nfigured to interrup t the co ntroller 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/outside the specified
range.
Figure 1.7. 12-Bit ADC Block Diagram
1.6. Two 12-bit Current-Mode DACs
The C8051F41x devices include two 12-bit current-mode Digital-to-Analog Converters (IDACs). The maxi-
mum current output of the IDACs can be adjusted for four different current settings; 0.25 mA, 0.5 mA,
1 mA, and 2 mA. A flexible output update mechanism allows for se amless full-scale chang es, and supports
jitter-free updates for waveform generation. The IDAC outputs can be merged onto a single port I/O pin for
increased full-scale current output or increased resolution. IDAC updates can be performed on-demand,
scheduled on a Timer overflow, or synchronized with an external signal. Figure 1.8 shows a block diagram
of the IDAC circuitry.
12-Bit
SAR
ADC
Timer 2 Overflow
Configuration, Control, and Data R egisters
Timer 3 Overflow
CNVSTR R ising Edge
Start
Conversion AD0BUSY (W)
16
Window Compare
Logic
Window
Compare
Interrupt
ADC Data
Registers
End of
Conversion
Interrupt
19-to-1
AMUX
P1.0
P1.7
P2.0
P2.7
P2.3-2.6
available on
C8051F410/2
An alog Multiplex er
VDD
Temp
Sensor
P0.0
P0.7 Burst Mode
Logic
Accumulator
GND
C8051F410/1/2/3
30 Rev. 1.1
Figure 1.8. IDAC Block Diagram
1.7. Programmable Comparators
C8051F41x devices inclu de two soft ware-config urable vo lt age comp ar ators with an input mu ltiplexer. Each
comparator offers programmable response time and hysteresis and two outputs that are optionally avail-
able at the Port pins: a synchronous “latched” output (CP0 and CP1), or an asynchronous “raw” output
(CP0A and CP1A). Comparator interrupts may be generated on rising, falling, or both edges. When in
IDLE or SUSPEND mode, these interrupts may be used as a “wake-up” source for the processor. Compar-
ator0 may also be configured as a re se t source. A block dia gram of the comparator is shown in Figure 1.9.
IDA0
12
Latch
12 Current
Output
12-bit Digi tal
Input
IDA1
12
Latch
12 Current
Output
12-bit Digi tal
Input
Data Write
Timer 0
Timer 1
Timer 2
Timer 3
CNVSTR
Data Write
Timer 0
Timer 1
Timer 2
Timer 3
CNVSTR
C8051F410/1/2/3
Rev. 1.1 31
Figure 1.9. Comparators Block Diagram
1.8. Cyclic Redundancy Check Unit
C8051F41x devices include a cyclic redundancy check unit (CRC0) that can perform a CRC using a 16-bit
or 32-bit polynomial. CRC0 accepts a stream of 8-bit data and outputs a 16-bit or 32-bit result. CRC0 also
has a hardware bit reverse feature for quick data manipulation.
1.9. Voltage Regulator
C8051F41x devices include an on-chip low dropout voltage regulator (REG0). The input to REG0 at the
VREGIN pin can be as high as 5.25 V. The output can be selected by software to 2.0 V or 2.5 V. W he n
enabled, the output of REG0 power s the device and dr ives the VDD pin. T he vo ltage regulator can be use d
to power external devices connected to VDD.
1.10. Serial Ports
The C8051F41x Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud rate
configuration, and an Enhanced SPI interface. Each of the serial buses is fully implemented in hardware
and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention.
VDD
Reset
Decision
Tree
+
- Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
(SYNCHRONIZER)
GND
CP0
(synchronous output)
CP0A
(asynchronous output)
Interru pt
Logic
Multiplexer
Port I/O
Pins
VDD
+
- Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
(SYNCHRONIZER)
GND
CP1
(synchronous output)
CP1A
(asynchronous output)
Interru pt
Logic
Multiplexer
Port I/O
Pins
C8051F410/1/2/3
32 Rev. 1.1
1.11. smaRTClock (Real Time Clock)
C8051F41x devices include a smaRTClock Peripheral (Real Time Clock). The smaRTClock has a dedi-
cated 32 kHz oscillator that can be configured for use with or without a crystal, a 47-bit smaRTClock timer
with alarm, a backup supply regulator, and 64 bytes of backup SRAM. When the backup supply voltage
(VRTC-BACKUP) is powered, the smaR TClock periph eral remains fully functional even if the core supply volt-
age (VDD) is lost.
The smaRTClock allows a maximum of 137 year 47-bit independent time-keeping when used with a
32.768 kHz Watch Crystal and backup supply voltage of at least 1 V. The switchover logic powers smaRT-
Clock from the backup supply when the voltage at VRTC-BACKUP is greater than VDD. The smaRTClock
alarm and missing clock detector can interrupt the CIP-51, wake the internal oscillator from SUSPEND
mode, or generate a device reset if the smaRTClock timer reaches a pre-set value or the oscillator stops.
Figure 1.10. smaRTClock Block Diagram
64B
Backup RA M
smaRT Clock O scillator
smaRTClock
CIP-51 CPU
XTAL4 XTAL3
Switchover
Logic
RTC0CN
CAPTUREn
ALARMn
RTC0XCN
RAMDATA
RAMADDR
RTC0KEY
RTC0ADR
RTC0DAT
Interface
Registers
Internal
Registers
smaR TClock State Mach ine
Interrupt
Backup
Regulator
VDD
VRTC-BACKUP
47-Bit
smaRTC lock
Timer
C8051F410/1/2/3
Rev. 1.1 33
1.12. Port Input/Output
C8051F41x devices include up to 24 I/O pins. Port pins are organized as three byte-wide ports. The port
pins behave like typical 8051 ports with a few enhancements. Each port pin can be co nfigur ed as a d igital
or analog I/O pin. Pins selected as digital I/O can be configured for push-pull or open-drain operation. The
“weak pullups” that are fixed on typical 8051 devices may be individually or globally disabled to save
power.
The Digital Crossbar allows mapping of internal digital system resources to port I/O pins. On-chip
counter/timers, serial buses, hardware interrupts, and other digital signals can be configured to appear on
the port pins using the Crossbar control registers. This allows the user to select the exact mix of general-
purpose port I/O, digital, and analog resources needed for the application.
Figure 1.11. Port I/O Functional Block Diagram
XBR0, XBR1,
PnSKIP Registers
Digital
Crossbar
Priority
Decoder
2
P0
I/O
Cells
P0.0
P0.7
8
P0MASK, P0MATCH
P1MASK, P1MATCH
Registers
UART
(Internal Digital Signals)
Highest
Priority
Lowest
Priority
SYSCLK
2
SMBus
T0, T1 2
7
PCA
4
CP0
CP1
Outputs
SPI 4
P1
I/O
Cells
P1.0
P1.7
8
(Port Latches)
P0 (P0.0-P0.7)
(P1.0-P1.7)
8
8
P1
P2
I/O
Cell
P2 (P2.0-P2.7)
8
8P2.0
P2.7
PnMDOUT,
PnMDIN Registers
P2.3–2.6 available on
C8051F410/2
C8051F410/1/2/3
34 Rev. 1.1
1.13. 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 six 16-bit capture/compare modules. The counter/timer is driven by a programmable timebase that
can select between seven sources: system clock, system clock divided by four, system clock divided by
twelve, the external oscillator clock source divided by 8, real-time clock source divided by 8, Timer 0 over-
flow, or an external clock signal on the External Clock Input (ECI) pin.
Each capture/compare module may be configured to operate independently in one of six modes: Edge-
Triggered Capture, Software Timer, High-Speed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM.
Additionally, PCA Module 5 may be used as a watchdog timer (WDT), and is enabled in this mode follow-
ing a system reset. The PCA Capture/Compare Module I/O and the External Clock Input ma y be rout ed to
Port I/O using the digital crossbar.
Figure 1.12. PCA Block Diagram
Capture/Compare
Module 1
Capture/Compare
Module 0 Capture/Compare
Module 2 Capture/Compare
Module 3
CEX1
ECI
Crossbar
CEX2
CEX3
CEX0
Port I/O
16-Bit Counter/Timer
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
smaRTClock/8
Capture/Compar e
Module 4
CEX4
Capture/Compar e
Module 5
CEX5
C8051F410/1/2/3
Rev. 1.1 35
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter Conditions Min Typ Max Units
Ambient temperature under bias –55 — 125 °C
Storage Temperature –65 — 150 °C
Voltage on VREGIN with respect to GND –0.3 — 5.5 V
Voltage on VDD with respect to GND –0.3 — 3.0 V
Voltage on VRTC-BACKUP with respect to GND –0.3 — 5.5 V
Voltage on XTAL1 with respect to GND –0.3 — VDD+ 0.3 V
Voltage on XTAL3 with respect to GND –0.3 — 5.5 V
V oltage o n any Port I/O Pin (except Port 0 pins) or
RST with respect to GND –0.3 — VIO + 0.3 V
Voltage on any Port 0 Pin with respect to GND 0.3 — 5.5 V
Maximum output current sunk by any Port pin — — 100 mA
Maximum output current sourced by any Port pin — — 100 mA
Maximum Total current through VDD, VIO,
VRTC-BACKUP, VREGIN, and GND ——500mA
*Note: S tresses 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.
C8051F410/1/2/3
36 Rev. 1.1
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C, 50 MHz System Clock unless otherwise specified. Typical values are given at 25 °C
Parameter Conditions Min Typ Max Units
Supply Input Voltage (VREGIN)1Output Current = 1 mA 2.15 —5.25 V
Core Supply Voltage (VDD)2.0 —2.75 V
I/O Supply Voltage (VIO)22.0 —5.25 V
Backup Supply Voltage (VRTC-BACKUP)31.0 —5.25 V
Backup Supply Current
(IRTC-BACKUP)
(VDD = 0 V, smaRTClock clock = 32 kHz)
VRTC-BACKUP = 1.0 V:
at –40 ºC
at 25 ºC
at 85 ºC
VRTC-BACKUP = 1.8 V:
at –40 ºC
at 25 ºC
at 85 ºC
VRTC-BACKUP = 2.5 V:
at –40 ºC
at 25 ºC
at 85 ºC
—
—
—
—
—
—
—
—
—
0.65
0.9
1.4
0.7
0.92
1.45
0.72
0.95
1.5
1.5
1.8
2.5
—
—
—
1.6
1.85
2.6
µA
µA
µA
µA
µA
µA
µA
µA
µA
Core Supply RAM Data Retention Voltage —1.5 — V
SYSCLK (System Clock)4,5 0 — 50 MHz
Sp ec ifie d Op er a ting Temp er ature Range –40 —+85 °C
Notes:
1. For more information on VREGIN characteristics, see Table 8.1 on page 82.
2. VIO must be equal to or greater th an VD D.
3. The Backup Supply Voltage (VRTC-BACKUP) is used to power the smaRTClock peripheral only.
4. SYSCLK is the internal device clock. For operational speeds in excess of 25 MHz, SYSCLK must
be derived from the internal clock multiplier.
5. SYSCLK must be at least 32 kHz to enable debugging.
6. Based on device characterization data, not production tested.
7. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated
using the IDD Supply Sensitivity. For example, if the VDD is 2.2 V instead of 2.0 V at 25 MHz:
IDD = 5.5 mA typical at 2.0 V and f = 25 MHz. From this, IDD = 5.5 mA + 1.14 x
(2.2 V – 2.0 V) = 5.73 mA at 2.2 V and f = 25 MHz.
8. IDD can be estimated for frequencies < 15 MHz by simply multiplying the frequency of interest by the
frequency sensitivity number for that range. When using these numbers to estimate IDD for >
15 MHz, the estimate sho uld be the cu rr en t at 25 MHz minus the difference in current indicated by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 20 MHz,
IDD = 5.5 mA – (25 MHz – 20 MHz) x 0.16 mA/MHz = 4.7 mA.
9. Idle IDD can be estimated for frequencies < 1 MHz by simply multiplying the frequency of inte rest by
the frequency sensitivity number for that range. When using these numbers to estimate Idle for >
1 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 5 MHz, Idle
IDD = 2.8 mA – (25 MHz – 5 MHz) x 0.1 mA/MHz = 0.8 mA.
C8051F410/1/2/3
Rev. 1.1 37
Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash)
Core Supply Current (IDD)6VDD = 2.0 V:
F = 32 kHz
F = 1 MHz
F = 25 MHz
F = 50 MHz
VDD = 2.5 V:
F = 32 kHz
F = 1 MHz
F = 25 MHz
F = 50 MHz
—
—
—
—
—
—
—
—
13
0.30
5.5
9.5
17
0.43
8.3
13.5
30
0.5
6.5
12
40
0.65
9.5
15
µA
mA
mA
mA
µA
mA
mA
mA
Supply Sensitivity (IDD)6,7 F = 25 MHz
F = 1 MHz —
—114
100 —
—%/V
%/V
Frequency Sensitivity (IDD)6,8 VDD = 2.0 V:
F < 15 MHz, T = 25 ºC
F > 15 MHz, T = 25 ºC
VDD = 2.5 V:
F < 15 MHz, T = 25 ºC
F > 15 MHz, T = 25 ºC
—
—
—
—
0.27
0.16
0.39
0.2
—
—
—
—
mA/MHz
mA/MHz
mA/MHz
mA/MHz
Table 3.1. Global DC Electrical Characteristics (Continued)
–40 to +85 °C, 50 MHz System Clock unless otherwise specified. Typical values are given at 25 °C
Parameter Conditions Min Typ Max Units
Notes:
1. For more information on VREGIN characteristics, see Table 8.1 on page 82.
2. VIO must be equal to or greater th an VD D.
3. The Backup Supply Voltage (VRTC-BACKUP) is used to power the smaRTClock peripheral only.
4. SYSCLK is the internal device clock. For operational speeds in excess of 25 MHz, SYSCLK must
be derived from the internal clock multiplier.
5. SYSCLK must be at least 32 kHz to enable debugging.
6. Based on device characterization data, not production tested.
7. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated
using the IDD Supply Sensitivity. For example, if the VDD is 2.2 V instead of 2.0 V at 25 MHz:
IDD = 5.5 mA typical at 2.0 V and f = 25 MHz. From this, IDD = 5.5 mA + 1.14 x
(2.2 V – 2.0 V) = 5.73 mA at 2.2 V and f = 25 MHz.
8. IDD can be estimated for frequencies < 15 MHz by simply multiplying the frequency of interest by the
frequency sensitivity number for that range. When using these numbers to estimate IDD for >
15 MHz, the estima te s hould be the cu rr en t at 25 MHz minu s the difference in curr e nt indi ca te d by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 20 MHz,
IDD = 5.5 mA – (25 MHz – 20 MHz) x 0.16 mA/MHz = 4.7 mA.
9. Idle IDD can be estimated for frequencie s < 1 MHz by simply multiplying the freq uency of interest by
the frequency sensitivity number for that range. When usin g these numbers to estimate Idle for >
1 MHz, the estimate should be the curren t at 25 MHz minus the difference in current indicated by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 5 MHz, Idle
IDD = 2.8 mA – (25 MHz – 5 MHz) x 0.1 mA/MHz = 0.8 mA.
C8051F410/1/2/3
38 Rev. 1.1
Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash)
Core Supply Current (IDD)6VDD = 2.0 V:
F = 32 kHz
F = 1 MHz
F = 25 MHz
F = 50 MHz
VDD = 2.5 V:
F = 32 kHz
F = 1 MHz
F = 25 MHz
F = 50 MHz
—
—
—
—
—
—
—
—
10
0.15
2.8
5
11
0.21
3.8
7.5
25
0.25
3.3
11
30
0.37
4.3
8.0
µA
mA
mA
mA
µA
mA
mA
mA
Supply Sensitivity (IDD)6,7 F = 25 MHz
F = 1 MHz —
—75
68 —
—%/V
%/V
Frequency Sensitivity (IDD)6,9 VDD = 2.0 V:
F < 1 MHz, T = 25 ºC
F > 1 MHz, T = 25 ºC
VDD = 2.5 V:
F < 1 MHz, T = 25 ºC
F > 1 MHz, T = 25 ºC
—
—
—
—
0.14
0.1
0.19
0.13
—
—
—
—
mA/MHz
mA/MHz
mA/MHz
mA/MHz
Digital Supply Current (Suspend Mode) Oscillator not running,
VDD = 2.5 V —0.15 50 µA
Digital Supply Current
(Stop Mode, shutdown) Oscillator not runn in g,
VDD = 2.5 V —0.15 50 µA
Table 3.1. Global DC Electrical Characteristics (Continued)
–40 to +85 °C, 50 MHz System Clock unless otherwise specified. Typical values are given at 25 °C
Parameter Conditions Min Typ Max Units
Notes:
1. For more information on VREGIN characteristics, see Table 8.1 on page 82.
2. VIO must be equal to or greater th an VD D.
3. The Backup Supply Voltage (VRTC-BACKUP) is used to power the smaRTClock peripheral only.
4. SYSCLK is the internal device clock. For operational speeds in excess of 25 MHz, SYSCLK must
be derived from the internal clock multiplier.
5. SYSCLK must be at least 32 kHz to enable debugging.
6. Based on device characterization data, not production tested.
7. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated
using the IDD Supply Sensitivity. For example, if the VDD is 2.2 V instead of 2.0 V at 25 MHz:
IDD = 5.5 mA typical at 2.0 V and f = 25 MHz. From this, IDD = 5.5 mA + 1.14 x
(2.2 V – 2.0 V) = 5.73 mA at 2.2 V and f = 25 MHz.
8. IDD can be estimated for frequencies < 15 MHz by simply multiplying the frequency of interest by the
frequency sensitivity number for that range. When using these numbers to estimate IDD for >
15 MHz, the estima te s hould be the cu rr en t at 25 MHz minu s the difference in curr e nt indi ca te d by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 20 MHz,
IDD = 5.5 mA – (25 MHz – 20 MHz) x 0.16 mA/MHz = 4.7 mA.
9. Idle IDD can be estimated for frequencie s < 1 MHz by simply multiplying the freq uency of interest by
the frequency sensitivity number for that range. When usin g these numbers to estimate Idle for >
1 MHz, the estimate should be the curren t at 25 MHz minus the difference in current indicated by
the frequency sensitivity number. For example: VDD = 2.0 V; F = 5 MHz, Idle
IDD = 2.8 mA – (25 MHz – 5 MHz) x 0.1 mA/MHz = 0.8 mA.
C8051F410/1/2/3
Rev. 1.1 39
Table 3.2. Index to Electrical Characteristics Tables
Table Title Page #
ADC0 Electrical Characteristics (VDD = 2.5 V, VREF = 2.2 V) 67
ADC0 Electrical Characteristics (VDD = 2.1 V, VREF = 1.5 V) 68
IDAC Electrical Characteristics 75
Voltage Reference Electrical Characteristics 79
Voltage Regulator Electrical Specifications 82
Comparator Electrical Characteristics 92
Reset Electrical Characteristics 134
Flash Electrical Characteristics 143
Port I/O DC Electrical Characteristics 163
Oscillator Electrical Characteristics 175
C8051F410/1/2/3
40 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 41
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F41x
Name Pin Numbers Type Description
‘F410/2 ‘F411/3
VDD 7 6 Core Supply Voltage.
VIO 128 I/O Supply Voltage.
GND 6 5 Ground.
VRTC-BACKUP 3 2 smaRTClock Backup Supply Voltage.
VREGIN 8 7 On-Chip Voltage Regulator Input.
RST/
C2CK
2 1
D I/O
D I/O
Device Reset. Open-drain output of internal POR or VDD
monitor. An external source can initiate a system rese t by
driving this pin low for at least 15 µs. A 1 kΩ pullup to VIO is
recommended. See Reset Sources Section for a complete
description.
Clock signal for the C2 Debug Interface.
P2.7/
C2D 32 27 D I/O
D I/O
Port 2.7. See Port I/O Section for a com p let e de sc rip tion .
Bi-directional data signal for the C2 Debug Interface.
XTAL3 5 4 A In smaRTClock Oscillator Crystal Input.
See Section 20. "smaRTClock (Real Time Clock)" for a
complete description.
XTAL4 4 3 A Out smaRTClock Oscillator Crystal Input.
See Section 20. "smaRTClock (Real Time Clock)" for a
complete description.
P0.0/
IDAC0 17 16
D I/O or
A In
A Out
Port 0.0. See Port I/O Section for a com p let e de sc rip tion .
IDAC0 Output. See IDAC Section for complete description.
P0.1/
IDAC1
18 17
D I/O or
A In
A Out
Port 0.1. See Port I/O Section for a com p let e de sc rip tion .
IDAC1 Output. See IDAC Section for complete description.
P0.2 19 18 D I/O or
A InPort 0.2. See Port I/O Section for a comp let e de sc rip tion .
P0.3 20 19 D I/O or
A InPort 0.3. See Port I/O Section for a comp let e de sc rip tion .
C8051F410/1/2/3
42 Rev. 1.1
P0.4/
TX
21 20
D I/O or
A In
D Out
Port 0.4. See Port I/O Section for a com p let e de sc rip tion .
UART TX Pin. See Port I/O Section for a complete descrip-
tion.
P0.5/
RX
22 21
D I/O or
A In
D In
Port 0.5. See Port I/O Section for a com p let e de sc rip tion .
UART RX Pin. See Port I/O Section for a complete descrip-
tion.
P0.6/
CNVSTR
23 22
D I/O or
A In
D In
Port 0.6. See Port I/O Section for a com p let e de sc rip tion .
External Convert S t art Input for ADC0, IDA0, and IDA1. See
ADC0 or IDACs section for a complete description.
P0.7 24 23 D I/O or
A InPort 0.7. See Port I/O Section for a comp let e de sc rip tion .
P1.0/
XTAL1
9 8
D I/O or
A In
A In
Port 1.0. See Port I/O Section for a com p let e de sc rip tion .
External Clock Input. This pin is the external oscillator
return for a crystal or resonator. See Oscillator Section.
P1.1/
XTAL2
10 9
D I/O or
A In
A O or
D In
Port 1.1. See Port I/O Section for a com p let e de sc rip tion .
External Clock Output. This pin is the excitation driver for an
external crystal or resonator, or an external clock input for
CMOS, capacitor, or RC oscillator configurations. See
Oscillator Section.
P1.2
VREF
11 10
D I/O or
A In
A In
Port 1.2. See Port I/O Section for a com p let e de sc rip tion .
External VREF Input. See VREF Section.
P1.3 12 11 D I/O or
A In Port 1.3. See Por t I/O Section for a com p let e de sc rip tion .
P1.4 13 12 D I/O or
A In Port 1.4. See Por t I/O Section for a com p let e de sc rip tion .
P1.5 14 13 D I/O or
A In Port 1.5. See Por t I/O Section for a com p let e de sc rip tion .
P1.6 15 14 D I/O or
A In Port 1.6. See Por t I/O Section for a com p let e de sc rip tion .
Table 4.1. Pin Definitions for the C8051F41x (Continued)
Name Pin Numbers Type Description
‘F410/2 ‘F411/3
C8051F410/1/2/3
Rev. 1.1 43
P1.7 16 15 D I/O or
A In Port 1.7. See Por t I/O Section for a com p let e de sc rip tion .
P2.0 25 24 D I/O or
A In Port 2.0. See Por t I/O Section for a com p let e de sc rip tion .
P2.1 26 25 D I/O or
A In Port 2.1. See Por t I/O Section for a com p let e de sc rip tion .
P2.2 27 26 D I/O or
A In Port 2.2. See Por t I/O Section for a com p let e de sc rip tion .
P2.3* 28 D I/O or
A In Port 2.3. See Por t I/O Section for a com p let e de sc rip tion .
P2.4* 29 D I/O or
A In Port 2.4. See Por t I/O Section for a com p let e de sc rip tion .
P2.5* 30 D I/O or
A In Port 2.5. See Por t I/O Section for a com p let e de sc rip tion .
P2.6* 31 D I/O or
A In Port 2.6. See Por t I/O Section for a com p let e de sc rip tion .
*Note: Available only on the C8051F410/2 .
Table 4.1. Pin Definitions for the C8051F41x (Continued)
Name Pin Numbers Type Description
‘F410/2 ‘F411/3
C8051F410/1/2/3
44 Rev. 1.1
Figure 4.1. LQFP-32 Pinout Diagram (Top View)
1
VRTC-BACKUP
P0.7
P0.2
P 0 .5 / RX
P0.6 / CNVSTR
P 0 .4 / T X
VDD
RST/C2CK
P 0 .1 / IDAC1
P 0 .0 / IDAC0
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
P0.3
C8051F410/2
Top View
VREGIN
XTAL4
XTAL3
VIO
P1.3
P1.4
P1.5
P1.6
P1.7 P2.0
P2.1
P1.2 / VREF
P2.3
P2.4
P2.5
P1.1 / XTAL2
P1.0 / XTAL1
GND
P2.2
P2.6
P2.7 / C2D
C8051F410/1/2/3
Rev. 1.1 45
Figure 4.2. QFN-28 Pinout Diagram (Top View)
4
5
6
7
2
1
3
11
12
13
14
9
8
10
18
17
16
15
20
21
19
25
26
27
28
23
22
24
C8051F411/3
Top View
RST / C2CK
VRTC-BACKUP
XTAL4
XTAL3
GND
VDD
VREGIN
P1.0 / XTAL 1
P1.1 / XTAL 2
P1.2 / VREF
P1.3
P1.4
P1.5
P1.6
P1.7
P 0 .0 / ID AC 0
P 0 .1 / ID AC 1
P0.2
P0.3
P 0 .4 / T X
P 0 .5 / R X
P0.6 / CNVSTR
P0.7
P2.0
P2.1
P2.2
P2.7 / C2D
VIO
GND
C8051F410/1/2/3
46 Rev. 1.1
Figure 4.3. LQFP-32 Package Diagram
Table 4.2. LQFP-32 Package Dimensions
MM
MIN TYP MAX
A——1.60
A1 0.05 — 0.15
A2 1.35 1.40 1.45
b 0.30 0.37 0.45
c 0.09 — 0.20
D — 9.00 —
D1 — 7.00 —
e — 0.80 —
E — 9.00 —
E1 — 7.00 —
L 0.45 0.60 0.75
C8051F410/1/2/3
Rev. 1.1 47
Figure 4.4. LQFP-32 Recommended PCB Land Pattern
Table 4.3. LQFP-32 PCB Land Pattern Dimensions
Dimension Min Max
C1 8.40 8.50
C2 8.40 8.50
E0.80 BSC
X1 0.40 0.50
Y1 1.25 1.35
C8051F410/1/2/3
48 Rev. 1.1
Figure 4.5. QFN-28 Package Drawing
Table 4.4. QFN-28 Package Dimensions
Dimension Min Typ Max Dimension Min Typ Max
A0.80 0.90 1.00 L0.35 0.55 0.65
A1 0.00 0.02 0.05 L1 0.00 —0.15
A3 0.25 REF aaa 0.15
b0.18 0.23 0.30 bbb 0.10
D5.00 BSC. ddd 0.05
D2 2.90 3.15 3.35 eee 0.08
e0.50 BSC. Z0.44
E5.00 BSC. Y0.18
E2 2.90 3.15 3.35
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14. 5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation VHHD except for
custom features D2, E2, Z, Y, and L whic h are toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small
Body Components.
C8051F410/1/2/3
Rev. 1.1 49
Figure 4.6. QFN-28 Recommended PCB Land Pattern
Table 4.5. QFN-28 PCB Land Pattern Dimensions
Dimension Min Max Dimension Min Max
C1 4.80 X2 3.20 3.30
C2 4.80 Y1 0.85 0.95
E0.50 Y2 3.20 3.30
X1 0.20 0.30
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification.
3. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design
4. All metal p ads are to be non-solder mask defined (NSMD). Clearance between the solder
mask and the metal pad is to be 60μm minimum, all the way around the pad.
Stencil Design
5. A st ainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used
to assure good solder paste release.
6. The stencil thickness should be 0.125mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
8. A 3x3 array of 0.90mm openings on a 1.1mm pitch should be used for the center pad to
assure the proper paste volume (67% Paste Coverage).
Card Assembly
9. A No-Clean, Type-3 solder paste is recommended.
10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for
Small Body Components.
C8051F410/1/2/3
50 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 51
5. 12-Bit ADC (ADC0)
The ADC0 subsystem for the C8051F41x consists of an analog multiplexer (AMUX0) with 27 total input
selections, and a 200 ksps, 12-bit successive-approximation-register ADC with integrated track-and-hold,
programmable window detector, and hardware accumulator. The ADC0 subsystem has a special Burst
Mode which can autom atically enab le ADC0 , capt ure an d accum ulate sample s, the n plac e ADC0 in a low
power shutd own mode without CPU interventio n. The AMUX0, data co nversion modes, and window detec-
tor are all configurable under software control via the Special Function Registers shown in Figure 5.1.
ADC0 inputs are single-ended and may be configured to measure P0.0-P2.7, the Temperature Sensor out-
put, VDD, or GND with respect to GND. ADC0 is enabled when the AD0EN bit in the ADC0 Control register
(ADC0CN) is set to logic 1, or when performing conversions in Burst Mode. ADC0 is in low power shut-
down when AD0EN is logic 0 and no Bu rst Mode conversions are taking place.
Figure 5.1. ADC0 Functional Block Diagram
5.1. Analog Multiplexer
AMUX0 selects the input channe l to the ADC. Any of the following may be selected as an input: P0.0-P2.7,
the on-chip temperature sensor, the core power supply (VDD), or ground (GND). ADC0 is single-ended
and all signals measured are with respect to GND. The ADC0 input channels are selected using the
ADC0MX register as described in SFR Definition 5.1.
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be config-
ured as analog inputs and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set to ‘0’ the corresponding bit in register PnMDIN (for n = 0,1,2) and write a ‘1’ in the corresponding
Port Latch register Pn (for n = 0,1,2). To force the Crossbar to skip a Port pin, set to ‘1’ the corresponding
bit in register PnSKIP (for n = 0,1,2). See Se ctio n “ 18 . Por t Input/Outp ut” on p a ge 147 for more Port I/O
configuration de tails.
12-Bit
SAR
ADC
REF
FCLK
ADC0H
32
ADC0CN
AD0CM0
AD0CM1
AD0LJST
AD0WINT
AD0BUSY
AD0INT
BURSTEN
AD0EN
Timer 2 Overflow
Start
Conversion
00 AD0BUSY (W)
VDD
ADC0LTH
AD0WINT
27-to-1
AMUX
VDD
P0.0
P0.7
01
10
11 CNVSTR Input
Window
Compare
Logic
P1.0
P1.7
Timer 3 Overflow
ADC0LTL
ADC0GTH ADC0GTL
ADC0L
ADC0MX
ADC0MX4
ADC0MX3
ADC0MX2
ADC0MX1
ADC0MX0
P2.0
P2.3-P2.6 available on
‘F410/2
P2.7
GND
Temp Sensor
ADC0CF
AD0RPT0
AD0RPT1
AD0SC0
AD0SC1
AD0SC2
AD0SC3
AD0SC4
ADC0TK
AD0PWR3
AD0PWR2
AD0PWR1
AD0PWR0
AD0TM1
AD0TM0
AD0TK1
AD0TK0
Burst Mode
Logic
AD0POST
AD0PRE
AD0TM1:0
Accumulator
Start
Conversion
Burst Mode
Oscillator
25 MHz Max
SYSCLK
FCLK
C8051F410/1/2/3
52 Rev. 1.1
5.2. Temperature Sensor
The typical t emper ature sensor transfe r func tion is show n in Figure 5.2. The output voltage (VTEMP) is the
positive ADC input when th e tem p er a ture sens or is selec ted by bits AD0MX4-0 in re gis ter ADC0 MX.
Figure 5.2. Typical Temperature Sensor Transfer Function
5.3. ADC0 Operation
In a typical system, ADC0 is configured using the following steps:
Ste p 1. Choos e th e start of conv er sio n sou r ce.
Step 2. Choose Normal Mode or Burst Mode operation.
Step 3. If Burst Mode, choose the ADC0 Idle Power State and set the Power-Up Time.
Step 4. Choose the tracking mode. Note that Pre-Tracking Mode can only be used with Normal
Mode.
Step 5. Calculate required settling time and set the post convert-start tracking time using the
AD0TK bits.
Step 6. Choose the repeat count.
Step 7. Choose the output word justification (Right-Justified or Left-Justified).
Step 8. Enable or disable the End of Conversion and Window Comparator Interrupts.
0-50 50 100 (Celsius)
0.500
0.600
0.700
0.800
0.900
(Volts)
VTEMP = SLOPE(TEMPC) + Offset
1.000
C8051F410/1/2/3
Rev. 1.1 53
5.3.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM1-0) in register ADC0CN. Conversions may be initiated by one of the fol-
lowing:
• Writing a ‘1’ to th e AD0BUSY bit of register ADC0CN
•A Timer 3 overflow (i.e., timed continuous conversions)
• A rising edge on the CNVSTR input signal (pin P0.6)
•A Timer 2 overflow (i.e., timed continuous conversions)
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 dat a registe rs, ADC0H:ADC0L , when b it AD0INT
is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte over-
flows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. Se e
Section “24. Timers” on page 231 for timer configuration.
Import ant 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 bit 6 in the P0SKIP register to logic 1. See Section
“18. Port Input/Output” on page 147 for details on Port I/O configur ation.
5.3.2. Tracking Modes
According to Table 5.3 and Table 5.4, each ADC0 conversion must be preceded by a minimum tracking
time for the converted result to be accurate. ADC0 has three tracking modes: Pre-Tracking, Post-Tracking,
and Dual-Tracking. Pre-Tracking Mode provides the minimum delay between the convert start signal and
end of conversion by tracking continuously before the convert start signal. This mode requires software
management in order to meet minimum tracking requirements. In Post-Tracking Mode, a programmable
tracking time starts after the convert start signal and is managed by hardware. Dual-Tracking Mode maxi-
mizes tracking time by tracking before and after the convert start signal. Figure 5.3 shows examples of the
three tracking mo de s.
Pre-Tracking Mode is se lected when AD0 TM is set to 10b. Conversions are started immediately following
the convert start signal. ADC0 is tracking continuously when not performing a conversion. Software must
allow at least the minimum tracking time betwe en each end of co nversion and the next con vert st art signal.
The minimum tracking time must also be met prior to the first convert start signal after ADC0 is enabled.
Post-Tracking Mode is selected when AD0TM is set to 01b. A programmable tracking time based on
AD0TK is started immediately following the convert start signal. Conversions are started after the pro-
grammed tracking time ends. After a conversion is complete, ADC0 does not track the input. Rather, the
sampling capacitor remains disconnected from the input making the input pin high-impedance until the
next convert start signal.
Dual-Tracking Mode is selected when AD0TM is set to 11b. A programmable tracking time based on
AD0TK is started immediately following the convert start signal. Conversions are started after the pro-
grammed tracking time ends. After a conversion is complete, ADC0 tracks continuously until the next con-
version is started.
C8051F410/1/2/3
54 Rev. 1.1
Depending on the output connected to the ADC input, additional tracking time, more than is specified in
Table 5.3 and Table 5.4, m ay be requ ired a fter chan ging MUX s ettin gs. Se e th e set tling t ime r equire men ts
described in Section “5.3.6. Settling Time Requirements” on page 58.
Figure 5.3. ADC0 Tracking Modes
5.3.3. Timing
ADC0 has a maximum conversion speed specified in Table 5.3 and Table 5.4. ADC0 is clocked from the
ADC0 Subsystem Clock (FCLK). The source of FCLK is selected based on the BURSTEN bit. When
BURSTEN is logic 0, FCLK is derived from the current system clock. When BURSTEN is logic 1, FCLK is
derived from the Burst Mode Oscillator, an independent clock source with a maximum frequency of
25 MHz.
When ADC0 is performing a conversion, it requires a clock source that is typically slower than FCLK. The
ADC0 SAR conversion clock (SAR clock) is a divided version of FCLK. The divide ratio can be configured
using the AD0SC bits in the ADC0CF register. The maximum SAR clock frequency is listed in Table 5.3
and Table 5.4.
ADC0 can be in one of th ree states at any g iven tim e: tracking, converting, or idle. Tracking time depends
on the tracking mode selected. For Pre-Tracking Mode, tracking is managed by software and ADC0 starts
conversions immediately following the convert start signal. For Post-Tracking and Dual-Tracking Modes,
the tracking time after the convert start signal is equal to the value determined by the AD0TK bits plus 2
FCLK cycles. Tracking is immediately followe d by a conversion. The ADC0 conversion time is always 13
SAR clock cycles plus an additional 2 FCLK cycles to start and complete a conversion. Figure 5.4 shows
timing diagrams for a conversion in Pre-Tracking Mode and tracking plus conversion in Post-Tracking or
Dual-Tracking Mode. In this example, repeat count is set to one.
Convert Start
Post-Tracking
AD0TM= 01 Track Convert IdleIdle Track Convert..
Pre-Tracking
AD0TM = 10 Track Convert Track Convert ...
Dual-Tracking
AD0TM = 11 Track Convert TrackTrack Track Convert..
C8051F410/1/2/3
Rev. 1.1 55
Figure 5.4. 12-Bit ADC Tracking Mode Example
Convert Start
ADC0 State Track
ADC0 State Convert
Time FS1 S2 S12 S13
... F
Time FS1 S2 S12 S13
... F
Convert
FS1 S2 F
Post-Tracking or Dual-Tracking Modes (AD0TK = ‘00')
Pre-Tracking Mode
AD0INT Flag
AD0INT Flag
Key
F
Sn
Equal to one period of FCLK.
Each Sn is equal to one period of the SAR clock.
C8051F410/1/2/3
56 Rev. 1.1
5.3.4. Burst Mode
Burst Mode is a power saving feature that allows ADC0 to remain in a low power state between conver-
sions. When Burst Mode is enab led, ADC0 wake s from a low powe r state, accumulates 1, 4, 8, or 16 sam-
ples using an internal Burst Mode clock (approximately 25 MHz), then re-enters a low power state. Since
the Burst Mode clock is independent of the system clock, ADC0 can perform multiple conversions then
enter a low power state within a single system clock cycle, even if the system clock is slow (e.g.
32.768 kHz), or suspended.
Burst Mode is enabled by setting BURSTEN to logic 1. When in Burst Mode, AD0EN controls the ADC0
idle power state (i.e. the state ADC0 enters when not tracking or performing conversions). If AD0EN is set
to logic 0, ADC0 is powered d own after each burst. If AD0EN is se t to log ic 1, ADC0 remains enabled after
each burst. On each conver t start signal, ADC0 is awakened fr om its Idle Power State. If ADC0 is powere d
down, it will automatically power up and wait the programmable Power-Up Time controlled by the
AD0PWR bits. Otherwise, ADC0 will st art tracking and converting immediately. Figure 5.5 shows an exam-
ple of Burst Mode Operation with a slow system clock and a repe at count of 4.
Import ant Note: Whe n Burst M ode is enable d, only Po st-Tracking and Dual-Tracking modes can be used.
When Burst Mode is enab led, a single convert star t will initiate a number of conversion s equal to the r epeat
count. When Burst Mode is disabled, a convert start is required to initiate each conversion. In both modes,
the ADC0 End of Conversion Interrupt Flag (AD0INT) will be set after “repeat count” conversions have
been accumulated. Similarly, the Window Comparator will not compare the result to the greater-than and
less-than registers until “repeat count” conversions have been accumulated.
Note: When using Burst Mod e, care must be t aken to issue a convert st art signal no faste r than once every
four SYSCLK periods. This includes external convert st art signals.
Figure 5.5. 12-Bit ADC Burst Mode Example with Repeat Count Set to 4
C onvert S tart
Post-Tracking
AD 0TM = 01
AD0EN = 0
Powered
Down Powered
Down
System C lock
T C
Power-Up
and Idle T C T C T C Power-Up
and Idle TC..
Dual-Tracking
AD 0TM = 11
AD0EN = 0
Powered
Down Powered
Down
T C
Power-Up
and Track T C T C T C Power-Up
and Track TC..
AD0PWR
Post-Tracking
AD 0TM = 01
AD0EN = 1 Idle IdleT C T C T C T C T C..
Dual-Tracking
AD 0TM = 11
AD0EN = 1 Track TrackT C T C T C T C T C..
T C T C
T C T C
T = Tracking
C = Converting
C8051F410/1/2/3
Rev. 1.1 57
5.3.5. Output Conversion Code
The registers ADC0H and ADC0L cont ain the high and low bytes of the output conversion code. When the
repeat count is set to 1, conversion codes are rep resented in 12-bit un signed integ er format an d the outp ut
conversion code is updated after each conversion. Inputs are measured from ‘0’ to VREF x 4095/4096.
Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit (ADC0CN.2).
Unused bits in the ADC0H and ADC0L registers are set to ‘0’. Example codes are shown in Table 5.1 for
both right-justified and left-justified data.
When the ADC0 Repe at Count is greate r than 1, the output conversion code represents the accumula ted
result of the conversions performed and is updated after the last conversion in the series is finished. Sets
of 4, 8, or 1 6 consecutive samples c an be accumulated an d represented in u nsigned integer form at. The
repeat count can be selected using the AD0RPT bits in the ADC0CF register. The value must be right-
justified (AD0LJST = “0”), and unused bits in the ADC0H and ADC0L registers are set to '0'. The example
in Table 5.2 shows the right-justified result for various input voltages and repeat counts. Notice that
accumulating 2n samples is equivalent to left-shifting by n bit positions when all samples returned from the
ADC have the same value.
Table 5.1. ADC0 Examples of Right- and Left-Justified Samples
Input Voltage Right-Justified ADC0H:ADC0L
(AD0LJST = 0) Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
VREF x 4095/4096 0x0FFF 0xFFF0
VREF x 2048/4096 0x0800 0x8000
VREF x 2047/4096 0x07FF 0x7FF0
0 0x0000 0x0000
Table 5.2. ADC0 Repeat Count Examples at Various Input Voltages
Input Voltage Repeat Count = 4 Repeat Count = 8 Repeat Count = 16
VREF x 4095/4096 0x3FFC 0x7FF8 0xFFF0
VREF x 2048/4096 0x2000 0x4000 0x8000
VREF x 2047/4096 0x1FFC 0x3FF8 0x7FF0
0 0x0000 0x0000 0x0000
C8051F410/1/2/3
58 Rev. 1.1
5.3.6. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This tracking time is
determined by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance,
and the accuracy required for the conversion.
Figure 5.6 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 VDD with respect to GND, RTOTAL
reduces to RMUX. See Table 5.3 and Table 5.4 for ADC0 minimum settling time requirements.
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 (12).
Figure 5.6. ADC0 Equivalent Input Circuits
t2n
SA
-------
RTOTALCSAMPLE
×ln=
RMUX = 5
CSAMPLE = 12 pF
RCInput= RMUX * CSAMPLE
MUX Select
Px.x
kΩ
C8051F410/1/2/3
Rev. 1.1 59
SFR Definition 5.1. ADC0MX: ADC0 Channel Select
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AD0MX4–0: AMUX0 Positive Input Selection
*Note: Only applies to C8051F410/2; selection RESERVED on C8051F411/3 devices.
R R R R/W R/W R/W R/W R/W Reset Value
- - - AD0MX 00011111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBB
AD0MX4–0 ADC0 Input Channel
00000 P0.0
00001 P0.1
00010 P0.2
00011 P0.3
00100 P0.4
00101 P0.5
00110 P0.6
00111 P0.7
01000 P1.0
01001 P1.1
01010 P1.2
01011 P1.3
01100 P1.4
01101 P1.5
01110 P1.6
01111 P1.7
10000 P2.0
10001 P2.1
10010 P2.2
10011 P2.3*
10100 P2.4*
10101 P2.5*
10110 P2.6*
10111 P2.7
11000 Temp Sensor
11001 VDD
11010 - 11111 GND
C8051F410/1/2/3
60 Rev. 1.1
SFR Definition 5.2. ADC0CF: ADC0 Configuration
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from FCL K by the following equation, wh ere AD0SC refers
to the 5-bit value held in bits AD0SC4-0. SAR Conversion clock requirements are given in
Table 5.3.
BURSTEN = 0: FCLK is the current system clock.
BURSTEN = 1: FCLK is a maximum of 25 MHz, independent of the current system clock.
* or
*Note: Round the result up.
Bits2–1: AD0RPT1–0: ADC0 Repeat Count.
Controls the number of conver sions taken and accumulated between ADC0 End of
Conversion (ADCINT) and ADC0 Window Comparator (ADCWINT) interrupts. A convert
start is required for each con ve rsion unless Burst Mode is enabled. In Burst Mode, a single
convert start can initiate multiple self-timed conversions. Results in both modes are
accumulated in the ADC0H:ADC0L register. When AD0RPT1-0 are set to a value other
than '00', the AD0LJST bit in the ADC0CN register must be set to '0' (right justified).
00: 1 conversion is performed.
01: 4 conversions are performed and accumulated.
10: 8 conversions are performed and accumulated.
11: 16 conversions are performed and accumulated.
Note: The ADC0 output register is automatically reset to 0x0000 upon reaching the last conversion
specified by the repeat counter . If the ADC is disabled during a conversion and re-enabled later ,
the ADC0H and ADC0L registers should be manually cleared to 0x00.
Bit0: RESERVED. Read = 0b; Must write 0b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0SC AD0RPT Reserved 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBC
AD0SC FCLK
CLKSAR
-------------------- 1–=
CLKSAR FCLK
AD0SC 1+
----------------------------
=
C8051F410/1/2/3
Rev. 1.1 61
SFR Definition 5.3. ADC0H: ADC0 Data Word MSB
SFR Definition 5.4. ADC0L: ADC0 Data Word LSB
Bits7-0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0 and AD0RPT as follows:
00: Bits 3–0 are the upper 4 bits of the accumulated result. Bits 7–4 are 0000b.
01: Bits 5–0 are the upper 6 bits of the accumulated result. Bits 7–6 are 00b.
10: Bits 6–0 are the upper 7 bits of the accumulated result. Bit 7 is 0b.
11: Bits 7–0 are the upper 8 bits of the accumulated result.
For AD0LJST = 1 (AD0RPT must be '00 '): Bits 7–0 are the most-significant bit s of the ADC0
12-bit result.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBE
Bits7-0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the ADC0 accumulated result.
For AD0LJST = 1 (AD0RPT must be '00'): Bits 7-4 are the lower 4 bits of the 12-bit result.
Bits 3-0 are 0000b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBD
C8051F410/1/2/3
62 Rev. 1.1
SFR Definition 5.5. ADC0CN: ADC0 Control
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.
Bit6: BURSTEN: ADC0 Burst Mode Enable Bit.
0: ADC0 Burst Mode Disabled.
1: ADC0 Burst Mode Enabled.
Bit5: AD0INT: ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since the last time AD0INT was cleared.
1: ADC0 has completed a data conversion.
Bit4: AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 conversion is complete or a co nversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM1-0 = 00b
Bit3: AD0WINT: ADC0 Window Compare Inte rr up t Fla g.
This bit must be cleared by software.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
Bit2: AD0LJST: ADC0 Left Justify Select
0: Data in ADC0H:ADC0L registers is right justified.
1: Data in ADC0H:ADC0L registers is left justified. This option should not be used with a
repeat count grea ter than 1 (when AD0RPT1-0 is 01b, 10b, or 11b).
Bits1-0: AD0 CM 1-0 : ADC0 Start of Conversio n Mo de S elect.
00: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
01: ADC0 conversion initiated on overflow of Timer 3.
10: ADC0 conversion initiated on rising edge of external CNVSTR.
11: ADC0 conversion initiated on overflow of Timer 2.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
AD0EN BURSTEN AD0INT AD0BUSY AD0WINT AD0LJST AD0CM1 AD0CM0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xE8
C8051F410/1/2/3
Rev. 1.1 63
SFR Definition 5.6. ADC0TK: ADC0 Tracking Mode Select
5.4. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-pro-
grammed limit s, and notifies the system whe n a desired co ndition is dete cted. This is especially ef fective i n
an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system
response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in
polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL)
registers hold the comp arison values. The window detector flag can be programmed to in dicate when mea-
sured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0
Less-Than and ADC0 Greater-Than registers.
Bits7–4: AD0PWR3–0: ADC0 Burst Power- Up Time.
For BURSTEN = 0:
ADC0 power state controlled by AD0EN.
For BURSTEN = 1 and AD0EN = 1;
ADC0 remains enabled and does not enter the low power state.
For BURSTEN = 1 and AD0EN = 0:
ADC0 enters the low power state as specified in Table 5.3 and Table 5.4 and is enabled
after each convert sta rt signal. The Power Up time is pr ogrammed according to the following
equation:
or
Bits3–2: AD0TM1–0: ADC0 Tracking Mode Select Bits.
00: Reserved.
01: ADC0 is configured to Post-Tracking Mode.
10: ADC0 is configured to Pre-Tracking Mode.
11: ADC0 is configured to Dual-Tracking Mode (default).
Bits1–0: AD0TK1–0: ADC0 Post-Track Time.
Post-Tracking time is controlled by AD0TK as follows:
00: Post-Tracking time is equal to 2 SAR clock cycles + 2 FCLK cycles.
01: Post-Tracking time is equal to 4 SAR clock cycles + 2 FCLK cycles.
10: Post-Tracking time is equal to 8 SAR clock cycles + 2 FCLK cycles.
11: Post-Tracking time is equal to 16 SAR clock cycles + 2 FCLK cycles.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
AD0PWR AD0TM AD0TK 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xBA
AD0PWR Tstartup
400ns
---------------------- 1–=
Tstartup AD0PWR 1+()400ns=
C8051F410/1/2/3
64 Rev. 1.1
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
Bits7–0: High byte of ADC0 Greater-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC4
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC3
C8051F410/1/2/3
Rev. 1.1 65
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
Bits7–0: High byte of ADC0 Less-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC6
Bits7–0: Low byte of ADC0 Le ss-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC5
C8051F410/1/2/3
66 Rev. 1.1
5.4.1. Window Detector In Single-Ended Mode
Figure 5.7 shows two example window comparisons for right-justified data with
ADC0LTH:ADC0LTL = 0x0200 (512d) and ADC0GTH:ADC0GTL = 0x0100 (256d). The input voltage can
range from ‘0’ to VREF x (4095/4096) with respect to GND, and is represented by a 12-bit unsigned integer
value. The repeat count is set to one. In the left example, an AD0WINT interrupt will be generated if the
ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and
ADC0LTH:ADC0LTL (if 0x0100 < ADC0H:ADC0L < 0x0200). In the right example, and AD0WINT interrupt
will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and
ADC0LT registers (if ADC0H:ADC0L < 0x0100 or ADC0H:ADC0L > 0x0200). Figure 5.8 shows an exam-
ple using left-justified data with the same comparison values.
Figure 5.7. ADC Window Compare Example: Right-Justified Single-Ended Data
Figure 5.8. ADC Window Compare Example: Left-Justified Single-Ended Data
0x0FFF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
0
Input Voltage
(Px.x - GND)
VREF x (4095/4096)
VREF x (512/4096)
VREF x (256/4096)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
0x0FFF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
0
Input Voltage
(Px.x - GND)
VREF x (4095/
4096)
VREF x (512/4096)
VREF x (256/4096)
AD0WINT
not affected
AD0WINT=1
AD0WINT=1
ADC0H:ADC0L ADC0H:ADC0L
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0xFFF0
0x2010
0x2000
0x1FF0
0x1010
0x1000
0x0FF0
0x0000
0
Input Voltage
(Px.x - GND)
VREF x (4095/4096)
VREF x (512/4096)
VREF x (256/4096)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
0xFFF0
0x2010
0x2000
0x1FF0
0x1010
0x1000
0x0FF0
0x0000
0
Input Voltag e
(Px.x - GND)
VREF x (4095/4096)
VREF x (512/4096)
VREF x (256/4096)
AD0WINT
not affected
AD0WINT=1
AD0WINT=1
ADC0H:ADC0L ADC0H:ADC0L
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
C8051F410/1/2/3
Rev. 1.1 67
Table 5.3. ADC0 Electrical Characteristics (VDD = 2.5 V, VREF = 2.2 V)
VDD = 2.5 V, VREF = 2.2 V (REFSL=0), –40 to +85 °C unless otherwise specified. Typical values are given
at 25 ºC.
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 12 bits
Integral Nonlinearity — — ±1 LSB
Differential Nonlinearity Guaranteed Monotonic — — ±1 LSB
Offset Error —±3 ±10 LSB
Full Scale Error —±3 ±10 LSB
Dynamic Performance (10 k Hz sine- wave Single-end ed input, 0 t o 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion Regular Mode (BURSTEN = '0 ')
Burst Mode (BURSTEN = '0') 66
60 69
63 —
—dB
Total Harmonic Distortion Up to the 5th harmonic —–77 —dB
Sp ur io us- Fre e Dyn a mic Rang e —–94 —dB
Conversion Rate
SAR Conversion Clock Regular Mode (BURSTEN = '0 ') — — 3 MHz
Conversion Time in SAR Clocks1—13 —clocks
Track/Hold Acquisition Time21 — — µs
Throughput Rate — — 200 ksps
Analog Inputs
Input Voltage Range 0 — VREF V
Input Capacitance —12 —pF
Temperature Sens or
Linearity3,4 —±0.2 —°C
Slope4—2.95 —mV/°C
Slope Error3—±73 —µV/°C
Offset4(Temp = 0 °C) —900 —mV
Offset Error3—±17 —mV
Power Specifications
Power Supply Current
(VDD supplied to ADC0) Operating Mode, 200 ksps —680 1000 µA
Burst Mode (Idle) —100 —µA
Power Supply Rejection — 1 — mV/V
Notes:
1. An additional 2 FCLK cycles are required to start and complete a conversion.
2. Additional tracking time may be required depending on the output impedance connected to the ADC inp ut.
See Section “5.3.6. Settling Time Requirements” on page 58.
3. Represents one standard deviation from the mean.
4. Includes ADC offset, gain, and linearity variations.
C8051F410/1/2/3
68 Rev. 1.1
Table 5.4. ADC0 Electrical Characteristics (VDD = 2.1 V, VREF = 1.5 V)
VDD = 2.1 V, VREF = 1.5 V (REFSL = 0), –40 to +85 °C unless otherwise specified. Typical values are given at
25 ºC.
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 12 bits
Integral Nonlinearity — — ±1 LSB
Differential Nonlinearity Guaranteed Monotonic — — ±1 LSB
Offset Error —±3 ±10 LSB
Full Scale Error —±3 ±10 LSB
Dynamic Performance (10 k Hz sine- wave Single-end ed input, 0 t o 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion Regular Mode (BURSTEN = '0 ')
Burst Mode (BURSTEN = '0') 66
60 68
62 —
—dB
Total Harmonic Distortion Up to the 5th harmonic —–75 —dB
Sp ur io us- Fre e Dyn a mic Rang e —–90 —dB
Conversion Rate
SAR Conversion Clock Regular Mode (BURSTEN = '0 ') — — 3 MHz
Conversion Time in SAR Clocks1—13 —clocks
Track/Hold Acquisition Time21 — — µs
Throughput Rate — — 200 ksps
Analog Inputs
Input Voltage Range 0 — VREF V
Input Capacitance —12 —pF
Temperature Sens or
Linearity3,4 —±0.2 —°C
Slope4—2.95 —mV/°C
Slope Error3—±73 —µV/°C
Offset (Temp = 0 °C) —900 —mV
Offset Error3—±17 —mV
Power Specifications
Power Supply Curre nt (VDD sup-
plied to ADC0) Operating Mode, 200 ksps —650 1000 µA
Burst Mode (Idle) —100 —µA
Power Supply Rejection — 1 — mV/V
Notes:
1. An additional 2 FCLK cycles are required to start and complete a conversion.
2. Additional tracking time may be required depending on the output impedance connected to the ADC inp ut.
See Section “5.3.6. Settling Time Requirements” on page 58.
3. Represents one standard deviation from the mean.
4. Includes ADC offset, gain, and linearity variations.
C8051F410/1/2/3
Rev. 1.1 69
6. 12-Bit Current Mode DACs (IDA0 and IDA1)
The C8051F41x devices include two 12-bit current-mode Digital-to-Analog Conver te rs ( IDACs). The max i -
mum current output of the IDACs can be adjusted for four different current settings; 0.25 mA, 0.5 mA,
1 mA, and 2 mA. The IDACs can be individually enabled or disabled using the enable bits in the corre-
sponding IDAC Control Register (IDA0CN or IDA1CN). When both IDACs are enabled, their outputs may
be routed to individual pins or merg ed onto a single pin. An intern al bandgap bias gene rator is used to gen-
erate a reference current for the IDACs whenever they are enabled. IDAC updates can be performed on-
demand, scheduled on a Timer overflow, or synchronized with an external pin edge. Figure 6.1 shows a
block diagram of the IDAC circuitry.
Figure 6.1. IDAC Functional Block Diagram
6.1. IDAC Output Scheduling
A flexible output update mechanism allows for seamless full-scale changes and supports jitter-free
updates for waveform generation. Three update modes are provided, allowing IDAC output updates on a
write to the IDAC’s data register, on a Timer overflow, or on an external pin edge.
6.1.1. Update Output On-Demand
In its default mode (IDAnCN.[6:4] = ‘111’) the IDAC output is updated “on-demand” with a write to the data
register high byte (IDAnH). It is important to note that in this mode, writes to the data register low byte
(IDAnL) are held and have no e ffect on the IDAn output until a write to IDAnH takes place. Since dat a fro m
both the high and low bytes of the dat a re gister are immed iately latched to IDAn af ter a write to IDAnH, the
write sequence when writing a full 12-bit word to the IDAC data registers should be IDAnL followed
by IDAnH. When the data word is left justified, the IDAC can be used in 8-bit mode by initializing IDAnL to
the desired value (ty pic ally 0x 00 ), and writin g data only to IDA0H .
IDAn
12 IDAn
Output
IDAnCN
IDAnEN
IDAnCM2
IDAnCM1
IDAnCM0
IDAnRJST
IDAnOMD1
IDAnOMD0
IDAnH
Latch
8
IDAnH
Timer 0
Timer 1
Timer 2
Timer 3
CNVSTR
IDAnL
4
C8051F410/1/2/3
70 Rev. 1.1
6.1.2. Update Output Based on Timer Overflow
The IDAC output update can be scheduled on a T imer overflow. This feature is useful in systems where the
IDAC is used to generate a waveform of a defined sampling rate, by eliminating the effects of variable
interrupt latency and instruction execution on the timing of the IDAC output. When the IDAnCM bits
(IDAnCN.[6:4] ) are set to ‘000 ’, ‘001’, ‘0 10’ or ‘011’, wr ites to both IDAC data registers (ID AnL and ID AnH)
are held until an associated Timer overflow event (Timer 0, Timer 1, Timer 2 or Timer 3, respectively)
occurs, at which time the IDAnH:IDAnL contents are copied to the IDAC input latch, al lowing the IDAC ou t-
put to change to the new value. When updates are scheduled based on Timer 2 or 3, updates occur on
low-byte overflows if Timer 2 or 3 is in 8-bit mode and high-byte overflows if Timer 2 or 3 is in 16-bit mode.
6.1.3. Update Output Based on CNVSTR Edge
The IDAC output can also be configured to update on a rising edge, falling edge, or both edges of the
external CNVSTR signal. When the IDAnCM bits (IDAnCN.[6:4]) are set to ‘100’, ‘101’, or ‘110’, writes to
the IDAC data registers (IDAnL and IDAnH) are held until an edge occurs on the CNVSTR input pin. The
particular setting of the IDAnCM bits determines whether the IDAC output is updated on rising, falling, or
both edges of CNVSTR. When a corresponding edge occurs, the IDAnH:IDAnL contents are copied to the
IDAC input latch, allowing the IDAC output to change to the new value.
6.2. IDAC Output Mapping
The IDAC data word can be Left Justified or Right Justified as shown in Figure 6.2. When Left Justified, the
8 MSBs of the data wor d (D11-D4) are mapped to bits 7-0 of the IDAnH register and the 4 LSBs of the dat a
word (D3-D0) are mapped to bits 7-4 of the IDAnL register. When Right Justified, the 4 MSBs of the data
word (D11 -D8) are mapped to bits 3-0 of the IDAnH register and the 8 LSBs of the data word (D7-D0) are
mapped to bits 7-0 of the IDAnL register. The IDAC data word justification is selected using the IDAnRJST
bit (IDAnCN.2).
The full-scale output current of the IDAC is selected using the IDAnOMD bits (IDAnCN[1:0]). By default,
the IDAC is set to a full-scale output current of 2 mA. The IDAnOMD bits can also be configur ed to provid e
full-scale output currents of 0.25 mA, 0.5 mA, or 1 mA.
Figure 6.2. IDAC Data Word Mapping
Left Justified Data (IDAnRJST = 0):
Right Justified Data (IDAnRJST = 1):
IDAnH IDAnL
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
IDAnH IDAnL
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
IDAn Data Word
(D11–D0) Output Current vs IDAnOMD bit setting
‘11’ (2 mA) ‘10’ (1 mA) ‘01’ (0.5 mA) ‘00’ (0.25 mA)
0x000 0 mA 0 mA 0 mA 0 mA
0x001 1/4096 x 2 mA 1/4096 x 1 mA 1/4096 x 0.5 mA 1/4096 x 0.25 mA
0x800 2048/4096 x 2 mA 2048/4096 x 1 mA 2048/4096 x 0.5 mA 2048/4096 x 0.25 mA
0xFFF 4095/4096 x 2 mA 4095/4 096 x 1 mA 4095/4096 x 0.5 mA 4095/4096 x 0.25 mA
C8051F410/1/2/3
Rev. 1.1 71
SFR Definition 6.1. IDA0CN: IDA0 Control
SFR Definition 6.2. IDA0H: IDA0 Data High Byte
Bit 7: IDA0EN: IDA0 Enable Bit.
0: IDA0 Disabled.
1: IDA0 Enabled.
Bits 6–4: IDA0CM[2:0]: IDA0 Update Source Select Bits.
000: DAC output updates on Timer 0 overflow.
001: DAC output updates on Timer 1 overflow.
010: DAC output updates on Timer 2 overflow.
011: DAC output updates on Timer 3 overflow.
100: DAC output updates on rising edge of CNVSTR.
101: DAC output updates on falling edge of CNVSTR.
110: DAC output updates on any edge of CNVSTR.
111 : DAC output updates on write to IDA0H.
Bit 3: Reserved. Read = 0b, Write = 0b.
Bit 2: IDA0RJST: IDA0 Right Justify Select Bit.
0: IDA0 data in IDA0H:IDA0L is left justified.
1: IDA0 data in IDA0H:IDA0L is right justified.
Bits 1:0: IDA0OMD[1:0]: IDA0 Output Mode Select Bits.
00: 0.25 mA full-scale output current.
01: 0.5 mA full-scale output current.
10: 1.0 mA full-scale output current.
11: 2.0 mA full-scale output current.
R/W R/W R/W R/W R/W R R/W R/W Reset Value
IDA0EN IDA0CM - IDA0RJST IDA0OMD 01110011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB9
Bits 7–0: IDA0 Dat a Word High-Order Bits.
For IDA0RJST = 0:
Bits 7-0 hold the most significant 8-bits of the 12-bit IDA0 Data Word.
For IDA0RJST = 1:
Bits 3-0 hold the most significant 4-bits of the 12-bit IDA0 Data Word. Bits 7-4 are 0000b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x97
C8051F410/1/2/3
72 Rev. 1.1
SFR Definition 6.3. IDA0L: IDA0 Data Low Byte
SFR Definition 6.4. IDA1CN: IDA1 Control
Bits 7–0: IDA0 Dat a Word Low-Order Bits.
For IDA0RJST = 0:
Bits 7-4 hold the least significant 4-bits of the 12-bit IDA0 Data Word. Bits 3–0 are 0000b.
For IDA0RJST = 1:
Bits 7–0 hold the least significant 8-bits of the 12-bit IDA0 Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x96
Bit 7: IDA1EN: IDA0 Enable Bit.
0: IDA1 Disabled.
1: IDA1 Enabled.
Bits 6–4: IDA1CM[2:0]: IDA1 Update Source Select Bits.
000: DAC output updates on Timer 0 overflow.
001: DAC output updates on Timer 1 overflow.
010: DAC output updates on Timer 2 overflow.
011: DAC output updates on Timer 3 overflow.
100: DAC output updates on rising edge of CNVSTR.
101: DAC output updates on falling edge of CNVSTR.
110: DAC output updates on any edge of CNVSTR.
111 : DAC output updates on write to IDA1H.
Bit 3: Reserved. Read = 0b, Write = 0b.
Bit 2: IDA1RJST: IDA1 Right Justify Select Bit.
0: IDA1 data in IDA1H:IDA1L is left justified.
1: IDA1 data in IDA1H:IDA1L is right justified.
Bits 1–0: IDA1OMD[1:0]: IDA1 Output Mode Select Bits.
00: 0.25 mA full-scale output current.
01: 0.5 mA full-scale output current.
10: 1.0 mA full-scale output current.
11: 2.0 mA full-scale output current.
R/W R/W R/W R/W R/W R R/W R/W Reset Value
IDA1EN IDA1CM - IDA1RJST IDA1OMD 01110011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB5
C8051F410/1/2/3
Rev. 1.1 73
SFR Definition 6.5. IDA1H: IDA0 Data High Byte
SFR Definition 6.6. IDA1L: IDA1 Data Low Byte
6.3. IDAC External Pin Connections
The IDA0 output is connected to P0.0, and the IDA1 output can be connected to P0.0 or P0.1. The output
pin for IDA1 is selected using IDAMRG (REF0CN.7). When the enable bits for both IDACs (IDAnEN) are
set to ‘0’, the IDAC outputs behave as a normal GPIO pins. When either IDAC’s enable bit is set to ‘1’, the
digital output drivers and weak pullup for the selected IDAC pin are automa tically disabled, and the pi n is
connected to the IDAC output. When using the IDACs, the selected IDAC pin(s) should be skipped in the
Crossbar by setting the corresponding PnSKIP bits to a ‘1’. Figure 6.3 shows the pin connections for IDA0
and IDA1.
When both IDACs are enabled and IDAMRG is set to logic 1, the output of both IDACs is merged onto
P0.0.
Bits 7–0: IDA1 Dat a Word High-Order Bits.
For IDA0RJST = 0:
Bits 7-0 hold the most significant 8-bits of the 12-bit IDA1 Data Word.
For IDA0RJST = 1:
Bits 3-0 hold the most significant 4-bits of the 12-bit IDA1 Data Word. Bits 7–4 are 0000b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF5
Bits 7–0: IDA1 Dat a Word Low-Order Bits.
For IDA0RJST = 0:
Bits 7-4 hold the least significant 4-bits of the 12-bit IDA1 Data Word. Bits 3–0 are 0000b.
For IDA0RJST = 1:
Bits 7–0 hold the least significant 8-bits of the 12-bit IDA1 Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF4
C8051F410/1/2/3
74 Rev. 1.1
Figure 6.3. IDAC Pin Connections
IDA0 P0.0
0
1
IDA0EN
IDA1 P0.1
0
1
IDA1EN
1
0
IDAMRG
C8051F410/1/2/3
Rev. 1.1 75
Table 6.1. IDAC Electrical Characteristics
–40 to +85 °C, VDD = 2.0 V Full-scale output current set to 2 mA unless otherwise specified. Typical values are given
at 25 ºC.
Parameter Conditions Min Typ Max Units
Static Performance
Resolution 12 bits
Integral Nonlinearity — — ±10 LSB
Differential Nonlinearity Guaranteed Monotonic — — ±1 LSB
Output Compliance Range Guaranteed by Design, Applies to
entire VDD range — — VDD – 1.2 V
Offset Error — 0 — LSB
Gain Error 2 mA Full Scale Output Current —0.05 2 %
Gain-Error Tempco —320 —nA/°C
VDD Power Supply Rejection
Ratio — 2 — µA/V
Output Capacitance — 2 — pF
Dynamic Performance
Startup Time —10 —µs
Gain Variation From 2 mA
range
1 mA Full Scale Output Current
0.5 mA Full Scale Outp ut Cu rr en t
0.25 mA Full Scale Output Curr ent —0.5
0.5
0.5 —%
%
%
Power Consumption
Power Supply Current
2 mA Full Scale Output Current
1 mA Full Scale Output Current
0.5 mA Full Scale Output Current
0.25 mA Full Scale Output Current
—
2.1
1.1
0.6
0.35
—
mA
mA
mA
mA
C8051F410/1/2/3
76 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 77
7. Voltage Reference
The Voltage referen ce MUX on C805 1F4 1x devi ce s is configura ble to use an externa lly conn ecte d vo ltage
reference, the internal reference voltage generator, or the VDD power supply voltage (see Figure 7.1). The
REFSL bit in the Reference Control register (REF0CN) selects the reference source. For an external
source or the internal reference, REFSL should be set to ‘0’. To use VDD as the reference source, REFSL
should be set to ‘1’.
The internal voltage reference circuit consists of a temperature stable bandgap voltage reference genera-
tor and a gain-of-two output buffer amplifier. The output voltage is selected between 1.5 V and 2.2 V. The
internal voltage reference can be driven out on the VREF pin by setting the REFBE bit in register REF0CN
to a ‘1’ (see Figure 7.1). The load seen by the VREF pin must draw less than 200 µA to GND. When using
the internal voltage reference, bypass capacitors of 0.1 µF and 4.7 µF are recommended from the VREF
pin to GND. If the internal reference is not used, the REFBE bit should be cleared to ‘0’.
The BIASE bit enables the internal voltage bi as generator, which is used by the ADC, Temperature Sensor,
internal oscillators, and IDACs. This bit is forced to logic 1 when any of the aforemention ed peripher als are
enabled. The bias generator may be enabled manually by writing a ‘1’ to the BIASE bit in register
REF0CN; see SFR Definition 7.1 for REF0CN register details.
The electrical specifications for the voltage reference circuit are given in Table 7.1.
Figure 7.1. Voltage Reference Functional Block Diagra m
REFLV
REFLV
C8051F410/1/2/3
78 Rev. 1.1
Import ant Note About the VREF Pin: Port pin P1.2 is used as the ex ternal VREF input and as a n output for
the internal VREF. When using either an external voltage reference or the internal reference circuitry, P1.2
should be configured as an analog pin, and skipped by the Digital Crossbar. To configure P1.2 as an ana-
log pin, clear Bit 2 in register P1MDIN to ‘0’ and set Bit 2 in register P1 to '1'. To configure the Crossbar to
skip P1.2, set Bit 2 in register P1SKIP to ‘1’. Refer to Section “18. Port Input/Output” on page 147 for
complete Port I/O configuration details. The TEMPE bit in register REF0CN enables/disables the tempera-
ture sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0
measurements performed on the sensor result in meaningless data.
SFR Definition 7.1. REF0CN: Reference Control
Bit7: IDAMRG: IDAC Output Merge Select.
0: IDA1 Output is P0.1.
1: IDA1 Output is P0.0 (Merged with IDA0 Output).
Bit6: GF. General Purpose Flag.
This bit is a general purpose flag for use under soft ware control.
Bit5: ZTCEN: Zero-TempCo Bias Enable Bit.
0: ZeroTC Bias Generator automatically enabled when needed.
1: ZeroTC Bias Generator forced on.
Bit4: REFLV: Voltage Reference Output Level Select.
This bit selects the output voltage level for the internal voltage reference.
0: Internal voltage reference set to 1.5 V.
1: Internal voltage reference set to 2.2 V.
Bit3: REFSL: Voltage Reference Select.
This bit selects the source for the internal voltage reference.
0: VREF pin used as voltage reference.
1: VDD used as voltage reference.
Bit2: TEMPE: Temperat ur e Sen so r Ena b le Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
Bit1: BIASE: Internal Analog Bias Generator Enable Bit.
0: Internal Analog Bias Generator automatically enabled when needed.
1: Internal Analog Bias Generator on.
Bit0: REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer disabled.
1: Internal Reference Buffer enabled. Internal voltage reference driven on the VREF pin.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
IDAMRG GF ZTCEN REFLV REFSL TEMPE BIASE REFBE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD1
C8051F410/1/2/3
Rev. 1.1 79
Table 7.1. Voltage Reference Electrical Characteristics
VDD = 2.0 V; –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Internal Reference (REFBE = 1)
Output Voltage 25 °C ambient (REFLV = 0)
25 °C ambient (REFLV = 1), VDD = 2.5 V 1.47
2.16 1.5
2.2 1.53
2.24 V
VREF Short-Circuit Current —3.0 —mA
VREF Temperature Coefficie nt —35 —ppm/°C
Load Regulation Load = 0 to 200 µA to GND —10 —ppm/µA
VREF Turn-on Time VDD = 2.5 V, VREF = 1.5 V:
4.7 µF tantalum, 0.1 µF ceramic bypass
0.1 µF ceramic bypass
VDD = 2.5 V, VREF = 2.2 V:
4.7 µF tantalum, 0.1 µF ceramic bypass
0.1 µF ceramic bypass
—
—
—
—
2.5
55
6.8
144
—
—
—
—
ms
µs
ms
µs
Power Supply Rejection — 2 — mV/V
External Reference (REFBE = 0)
Input Voltage Range 0 — VDD V
Input Current Sample Rate = 200 ks ps; VREF = 2 V — 5 — µA
Bias Generators
ADC Bias Generator BIASE = ‘1’ —22 —µA
Power Consumption (Internal) —50 —µA
C8051F410/1/2/3
80 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 81
8. Voltage Regulator (REG0)
C8051F41x devices include an on-chip low dropout voltage regulator (REG0). The input to REG0 at the
VREGIN pin can be as high as 5.25 V. The output can be selected by software to 2.1 V or 2.5 V. W hen
enabled, the output of REG0 appears on th e VDD pin, powers the microcontroller core, and can be used to
power external devices. On reset, REG0 is enabled and can be disabled by software .
The input (VREGIN) and output (VDD) of the voltage regulator should both be protected with a large capaci-
tor (4.7 µF + 0.1 µF) to ground. This capacitor will eliminate power spikes and provide any immediate
power required by the microcontroller. A settling time associated with the voltage regulator is shown in
Table 8.1.
Figure 8.1. External Capacitors for Voltage Regulator Input/Output
If the internal volt ag e regulator is not used, the VREGIN input should be tied to VDD, as shown in Figure 8.2.
Figure 8.2. External Capacitors for Voltage Regulator Input/Output
VDD
VDD
REG0
4.7 µF
4.7 µF .1 µF
.1 µF
VREGIN
VREGIN
VDD
VDD
4.7 µF .1 µF
C8051F410/1/2/3
82 Rev. 1.1
SFR Definition 8.1. REG0CN: Regulator Control
Table 8.1. Voltage Regulator Electrical Specifications
VDD = 2.1 or 2.5 V; –40 to +85 °C unless otherwise specified. Typical values are given at 25 ºC.
Parameter Conditions Min Typ Max Units
Input Voltage Range (VREGIN)* (See Note) —5.25 V
Load Current — — 50 mA
Load Regulation — 7 15 mV/mA
Output Voltage (VDD)Output Current = 1 mA
REG0MD = ‘0’
REG0MD = ‘1’ 2.0
2.35 2.1
2.5 2.25
2.55 V
Bias Current REG0MD = ‘0’
REG0MD = ‘1’ —
—1
11.5
1.5 µA
Dropout Indicator Detection
Threshold —65 —mV
Output Voltage Tempco —600 —µV/ºC
VREG Settling Time 50 mA load with VREGIN = 2.5 V
and VDD load capacitor of 4.8 µF —250 —µs
*Note: Actual Output Voltage (VDD) = Nominal Output Voltage (VDD) – (Load Regulation x Load Current).
Bit 7: REGDIS: Voltage Regulator Disable Bit.
This bit disables/enables the Volt age Regulator.
0: Voltage Regulator Enabled.
1: Voltage Regulator Disabled.
Bit 6: RESERVED. Read = 0b. Must write 0b.
Bit 5: UNUSED. Read = 0b. Write = don’t care.
Bit 4: REG0MD: Voltage Regulator Mode Select Bit.
This bit selects the Voltage Regulator output voltage.
0: Voltage Regulator output is 2.1 V.
1: Voltage Regulator output is 2.5 V (default).
Bits 3–1: UNUSED. Read = 0b. Write = don’t care.
Bit 0: DROPOUT: Voltage Regulator Dropout Indicator Bit.
0: Voltage Regulator is not in dropout.
1: Voltage Regulator is in or near dropo ut .
R/W R/W R R/W R R R R Reset Value
REGDIS Reserved — REG0MD — — — DROPOUT 00010000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC9
C8051F410/1/2/3
Rev. 1.1 83
9. Comparators
C8051F41x devices include two on-chip programmable voltage comparators: Comparator0 is shown in
Figure 9.1; Comparator1 is shown in Figure 9.2. The two comparators operate identically, but only Com-
parator0 can be used as a reset source.
The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two
outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an
asynchronous “raw” output (CP0A, CP1A). The asynchronous CP0A signal is available even when the
system clock is not active. This allows the Comparator to operate and generate an output with the device
in STOP or SUSPEND mode. When assigned to a Port pin, the Comparator output may be co nfigured as
open drain or push-pull (see Section “18.2. Port I/O Initialization” on page 151). Comparator0 may also
be used as a reset source (see Section “15.5. Comparator0 Reset” on page 130).
The Compara tor0 input s are se lected in the CPT0 MX register (SFR Definition 9.2). The CMX0P3-CMX0P0
bits select the Comparator0 positive input; the CMX0N3-CMX0N0 bits select the Comparator0 negative
input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 9.4). The CMX1P3-
CMX1P0 bits select the Comparator1 positive input; the CMX1N3-CMX1N0 bits select the Comparator1
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 (with a ‘1’ written to the correspond-
ing Port Latch register), and configured to be skipped by the Crossbar (for details on Port configuration,
see Section “18.3. Gene ral Purpose Port I/O” on page 154)
Figure 9.1. Comparator0 Functional Block Diagram
VDD
CPT0CN
Reset
Decision
Tree
+
- Crossbar
Interrupt
Logic
Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
(SYNCHRONIZER)
GND
CP0 +
CP0 -
P0.1
P0.3
P0.5
P0.7
CP0EN
CP0OUT
CP0RIF
CP0FIF
CP0HYP1
CP0HYP0
CP0HYN1
CP0HYN0
CPT0MX
CMX0N3
CMX0N2
CMX0N1
CMX0N0
CMX0P3
CMX0P2
CMX0P1
CMX0P0
CPT0MD
CP0RIE
CP0FIE
CP0MD1
CP0MD0
CP0
CP0A
CP0
Rising-edge CP0
Falling-edge
CP0
Inte r rupt
P1.1
P1.3
P1.5
P1.7
P2.1
P2.3
P2.5
P2.7
P0.0
P0.2
P0.4
P0.6
P1.0
P1.2
P1.4
P1.6
P2.0
P2.2
P2.4
P2.6
C8051F410/1/2/3
84 Rev. 1.1
The Comparator output can be polled in software, used as an interrupt source, internal oscillator suspend
awakening so urce and/or rout ed to a Port pin. When ro uted to a Port pin, th e Comparator output is avail -
able asynchronous or synchronous to the system clock; the asynchronous output is available even in
STOP or SUSPEND mode (with no system clock active). When disabled, the Comparator output (if
assigned to a Port I/O pin via the Crossbar) defaults to the logic low state, and its supply current falls to
less than 100 nA. See Section “18.1. Priority Crossbar Decode r” on p a ge 149 for de tails on configuring
Comparator outputs via the digital Crossbar. Comparator inputs can be externally driven from -0.25 V to
(VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in
Table 9.1.
The Comparator response time may be configured in software via the CPTnMD r egisters (see SFR Defini-
tion 9.3 and SFR Definition 9.5). Selecting a longer response time reduces the Comparator supply cu rr ent.
See Table 9.1 for complete timing and current consumption specifications.
Figure 9.2. Comparator1 Functional Block Diagram
VDD
CPT1CN
+
- Crossbar
Inte r rup t
Logic
Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
(SYNCHRONIZER)
GND
CP1 +
P0.0
P0.2
P0.4
P0.6
CP1 -
P0.1
P0.3
P0.5
P0.7
CP1EN
CP1OUT
CP1RIF
CP1FIF
CP1HYP1
CP1HYP0
CP1HYN1
CP1HYN0
CPT1MX
CMX1N3
CMX1N2
CMX1N1
CMX1N0
CMX1P3
CMX1P2
CMX1P1
CMX1P0
CPT1MD
CP1RIE
CP1FIE
CP1MD1
CP1MD0
CP1
CP1A
CP1
Rising-edge CP1
Falling-edge
CP1
Interrupt
P1.0
P1.2
P1.4
P1.6
P2.0
P2.2
P2.4
P2.6
P1.1
P1.3
P1.5
P1.7
P2.1
P2.3
P2.5
P2.7
C8051F410/1/2/3
Rev. 1.1 85
Figure 9.3. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN (for
n = 0 or 1). The us er can p rog ra m bo th the a mou nt of h ysteresis voltage (refer re d to the inp ut voltage) and
the positive and negat i ve -g oin g sym m et ry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN
(shown in SFR Definition 9.1 and SFR Definition 9.6). The amount of negative hysteresis voltage is
determined by the settings of the CPnHYN bits. As shown in Table 9.1, settings of 20, 10 or 5 mV of
negative hysteresis can be programmed, or negative hysteresis can be disabled. In a similar way, the
amount of positive hysteresis is determined by setting the CPnHYP bits.
Compara tor interrup ts can be generated on both rising-e dge and falling -e dge output tr an sitions. (Fo r In te r -
rupt enable and priority control, see Section “12. Interrupt Handler” on page 110). The CPnFIF flag is
set to logic 1 upon a Comparator falling-edge detect, and the CPnRIF flag is set to logic 1 upon the Com-
parator rising-edge detect. Once set, these bits remain set until cleared by software. The output state of
the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by
setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0.
The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Compar-
ator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0. When the
Comparator is enabled, the internal oscillator is awakened fro m SUSPEND mode if the Compar ator output
is logic 0.
Note that false rising edges and falling edges can be detected when the comparator is first powered-on or
if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the
rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is
enabled or its mode bits have been changed. This Power Up Time is specified in Table 9.1 on page 92.
Positive Hysteresis Vol tag e
(Programmed wi t h CP0HYP Bi ts)
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN-
VIN+
INPUTS
CIRCUIT CONFIGURATION
+
_
CP0+
CP0- CP0
VIN+
VIN- OUT
V
OH
Positive Hysteresis
Disabled Maximum
Positive Hysteresis
Negative Hysteresis
Disabled Maximum
Negative Hysteresis
OUTPUT
V
OL
C8051F410/1/2/3
86 Rev. 1.1
SFR Definition 9.1. CPT0CN: Comparator0 Control
Bit7: CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6: CP0OUT: Comparator0 Ou tp ut State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5: CP0RIF: Comparator0 Risin g -Edge Fla g.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Bit4: CP0FIF: Comparator0 Falling-Edge Flag.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge 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 Hyster esis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
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:
0x9B
C8051F410/1/2/3
Rev. 1.1 87
SFR Definition 9.2. CPT0MX: Comparator0 MUX Selection
Bits7–4: CMX0N3–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
Bits1–0: CMX0P3–CMX0P0: Compar ator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CMX0N3 CMX0N2 CMX0N1 CMX0N0 CMX0P3 CMX0P2 CMX0P1 CMX0P0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9F
CMX0N3 CMX0N2 CMX0N1 CMX0N0 Negative Input
0000 P0.1
0001 P0.3
0010 P0.5
0011 P0.7
0100 P1.1
0101 P1.3
0110 P1.5
0111 P1.7
1000 P2.1
1001 P2.3
*
1010 P2.5*
1011 P2.7
11xxReserved
*Note: Available only on the C8051F410/2.
CMX0P3 CMX0P2 CMX0P1 CMX0P0 Positive Input
0000 P0.0
0001 P0.2
0010 P0.4
0011 P0.6
0100 P1.0
0101 P1.2
0110 P1.4
0111 P1.6
1000 P2.0
1001 P2.2
1010 P2.4
*
1011 P2.6*
11xxReserved
*Note: Available only on the C8051F410/2.
C8051F410/1/2/3
88 Rev. 1.1
SFR Definition 9.3. CPT0MD: Comparator0 Mode Selection
Bit7: RESERVED. Read = 0b. Must Write 0b.
Bit6: UNUSED. Read = 0b. Write = don’t care.
Bit5: CP0RIE: Comparator Rising-Edge Interrupt Enable.
0: Comparator rising-edge interrupt disabled.
1: Compar ator rising-edge interrupt enabled.
Bit4: CP0FIE: Comparator Falling-Edge Interrupt Enable.
0: Compar ator falling-edge interrup t disabled.
1: Compar ator falling-edge interrupt enabled.
Bits3–2: UNUSED. Read = 00b. Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits affect the response time and power consumption for Compa rator0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
RESERVED - CP0RIE CP0FIE - - CP0MD1 CP0MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9D
Mode CP0MD1 CP0MD0 Effect
0 0 0 Fastest Response Time
101 —
210 —
3 1 1 Lowest Power Consumption
C8051F410/1/2/3
Rev. 1.1 89
SFR Definition 9.4. CPT1MX: Comparator1 MUX Selection
Bits7–4: CMX1N3–CMX1N0: Comparator1 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator1 negative input.
Bits3–0: CMX1P3–CMX1P0: Compar ator1 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator1 positive input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CMX1N3 CMX1N2 CMX1N1 CMX1N0 CMX1P3 CMX1P2 CMX1P1 CMX1P0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9E
CMX1N3 CMX1N2 CMX1N1 CMX1N0 Negative Input
0000 P0.1
0001 P0.3
0010 P0.5
0011 P0.7
0100 P1.1
0101 P1.3
0110 P1.5
0111 P1.7
1000 P2.1
1001 P2.3
*
1010 P2.5*
1011 P2.7
11xxReserved
*Note: Available only on the C8051F410/2.
CMX1P3 CMX1P2 CMX1P1 CMX1P0 Positive Input
0000 P0.0
0001 P0.2
0010 P0.4
0011 P0.6
0100 P1.0
0101 P1.2
0110 P1.4
0111 P1.6
1000 P2.0
1001 P2.2
1010 P2.4
*
1011 P2.6*
11xxReserved
*Note: Available only on the C8051F410/2.
C8051F410/1/2/3
90 Rev. 1.1
SFR Definition 9.5. CPT1MD: Comparator1 Mode Selection
Bit7: RESERVED. Read = 0b. Must Write 0b.
Bit6: UNUSED. Read = 0b. Write = don’t care.
Bit5: CP1RIE: Comparator Rising-Edge Interrupt Enable.
0: Comparator rising-edge interrupt disabled.
1: Compar ator rising-edge interrupt enabled.
Bit4: CP1FIE: Comparator Falling-Edge Interrupt Enable.
0: Compar ator falling-edge interrup t disabled.
1: Compar ator falling-edge interrupt enabled.
Bits3–2: UNUSED. Read = 00b. Write = don’t care.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select.
These bits affect the response time and power consumption for Compa rator1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
RESERVED - CP1RIE CP1FIE - - CP1MD1 CP1MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9C
Mode CP1MD1 CP1MD0 Effect
000Fastest Response Time
101 —
210 —
3 1 1 Lowest Power Consumption
C8051F410/1/2/3
Rev. 1.1 91
SFR Definition 9.6. CPT1CN: Comparator1 Control
Bit7: CP1EN: Comparator1 Enable Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
Bit6: CP1OUT: Comparator1 Ou tp ut State Flag.
0: Voltage on CP1+ < CP1-.
1: Voltage on CP1+ > CP1-.
Bit5: CP1RIF: Comparator1 Risin g -Edge Fla g.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
Bit4: CP1FIF: Comparator1 Falling-Edge Flag.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hyster esis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
R/W R R/W R/W R/W R/W R/W R/W Reset Value
CP1EN CP1OUT CP1RIF CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9A
C8051F410/1/2/3
92 Rev. 1.1
Table 9.1. Comparator Electrical Characteristics
VDD = 2.0 V, –40 to +85 °C unless otherwise noted. All specifications apply to both Comparator0 and Comparator1
unless otherwise noted. Typical values are given at 25 ºC.
Parameter Conditions Min Typ Max Units
Response Time:
Mode 0, Vcm1 = 1.5 V CP0+ – CP0– = 100 mV —120 —ns
CP0+ – CP0– = –100 mV —160 —ns
Response Time:
Mode 1, Vcm1 = 1.5 V CP0+ – CP0– = 100 mV —200 —ns
CP0+ – CP0– = –100 mV —340 —ns
Response Time:
Mode 2, Vcm1 = 1.5 V CP0+ – CP0– = 100 mV —360 —ns
CP0+ – CP0– = –100 mV —720 —ns
Response Time:
Mode 3, Vcm1 = 1.5 V CP0+ – CP0– = 100 mV —2.2 —µs
CP0+ – CP0– = –100 mV —7.2 —µs
Common-Mode Rejection Ratio2—1.5 14 mV/V
Positive Hysteresis 1 CP0HYP1-0 = 00 —0.5 2.0 mV
Positive Hysteresis 2 CP0HYP1-0 = 01 24.5 10 mV
Positive Hysteresis 3 CP0HYP1-0 = 10 59.0 20 mV
Positive Hysteresis 4 CP0HYP1-0 = 11 13 18.0 40 mV
Negative Hysteresis 1 CP 0HY N 1- 0 = 00 —–0.5 –2.0 mV
Negative Hysteresis 2 CP 0HY N 1- 0 = 01 –2 –4.5 –10 mV
Negative Hysteresis 3 CP 0HY N 1- 0 = 10 –5 –9.0 –20 mV
Negative Hysteresis 4 CP0HYN1-0 = 11 –13 –18.0 –40 mV
Inverting or Non-Inverting Input
Voltage Range –0.25 — VDD + 0.25 V
Input Capacitance — 4 — pF
Input Bias Current —0.5 —nA
Input Offset Voltage –10 —10 mV
Power Supply
Power Supply Rejection2 —0.2 4mV/V
Power-up Time —2.3 —µs
Supply Current at DC
Mode 0 —13 30 µA
Mode 1 —6.0 20 µA
Mode 2 —3.0 10 µA
Mode 3 —1.0 5µA
Notes:
1. Vcm is the common-mode voltage on CP0+ and CP0–.
2. Guaranteed by design and/or characterization.
C8051F410/1/2/3
Rev. 1.1 93
10. 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 C8051F41x family has a superset of all the peripherals included with a standard 8051. See Sec-
tion “1. System Overview” on page 19 for more information about the available peripherals. The CIP-51
includes on-chip debug hardware which interfaces directly with the analog and digital subsystems, provid-
ing 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 10.1 for a block diagram).
The CIP-51 core includes the following features:
Figure 10.1. CIP-51 Block Diagram
- Fully Compatible with MCS-51 Instruction
Set
- 50 MIPS Peak Throughput
- 256 Bytes of Internal RAM
- Extended Interrupt Handler
- Reset Input
- Power Management Modes
- Integrated Debug Logic
DATA BUS
TMP1 TMP2
PRGM. ADDRESS REG.
PC INCREMENTER
ALU
PSW
DATA BUS
DATA B US
MEMORY
INTERFACE
MEM_ADDRESS
D8
PIPELINE
BUFFER
DATA POINTER
INTERRUPT
INTERFACE
SYSTEM_IRQs
EMULATION_IRQ
MEM_CONTROL
CONTROL
LOGIC
A16
PROGRAM COUNTER (PC)
STOP
CLOCK
RESET
IDLE POWER CONTROL
REGISTER
DATA BUS
SFR
BUS
INTERFACE
SFR_ADDRESS
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
D8
D8
B REGISTER
D8
D8
ACCUMULATOR
D8
D8
D8
D8
D8
D8
D8
D8
MEM_WRITE_DATA
MEM_READ_DATA
D8
SRAM
ADDRESS
REGISTER
SRAM
(256 X 8)
D8
STACK POINTER
D8
C8051F410/1/2/3
94 Rev. 1.1
Performance
The CIP-51 emplo ys a p ipeli ned architectu re tha t grea tly increases its instruction throughpu t over the st an-
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 system clock runn ing at 50 MHz, it h as a peak th rough put of 50 MIPS. The CIP-51 has a
total of 109 instructions. The t able below shows th e tot al number of instruction s that require ea ch execution
time.
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Silicon Labs 2-Wire (C2) interface. Note that the re-programmable Flash can
also be read and written a single byte at a time by the application software using the MOVC and MOVX
instructions. This feature allo ws program memo ry to be used for non-volatile da ta stora ge as well as updat-
ing program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints, starting, stopping and single stepping through program execution (including interrupt service
routines), examination of the program's call stack, and reading/writing the contents of registers and mem-
ory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or
other on-c hip res ou rces.
The CIP-51 is supported by development tools from Silicon Laboratories, Inc. and third party vendors. Sili-
con Laboratories provides an integrated development environment (IDE) including editor, evaluation com-
piler, assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51
via the on-chip debug logic to provide fast and efficient in-system device programming and debugging.
Third party macro assemblers and C compilers are also available.
10.1. 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.
10.1.1. 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 two less clock
cycles to complete when the branch is not t aken as opposed to when the bran ch is t aken. Table 10.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
Clocks to Execute 1 2 2/4 33/5 4 5 4/6 6 8
Number of Instructions 26 50 510 752121
C8051F410/1/2/3
Rev. 1.1 95
10.1.2. MOVX Instruction and Program Memory
The MOVX instruction is typically used to access data stored in XDATA memory space. In the CIP-51, the
MOVX instructio n can also be us ed to write or eras e on-chip progra m memory space implem ented as re-
programmable Flash memory. The Flash access feature provides a mechanism for the CIP-51 to update
program code and use the program memory space for non-volatile data storage. Refer to Section
“16. Flash Memory” on page 135 for further details.
Table 10.1. CIP-51 Instruction Set Summary1
Mnemonic Description Bytes Clock
Cycles
Arithmetic Operations
ADD A, Rn Add register to A 1 1
ADD A, direct Add direct byte to A 2 2
ADD A, @Ri Add indirect RAM to A 1 2
ADD A, #data Add immediate to A 2 2
ADDC A, Rn Add register to A with carry 1 1
ADDC A, direct Add direct byte to A with carry 2 2
ADDC A, @Ri Add indirect RAM to A with carry 1 2
ADDC A, #data Add immediate to A with carry 2 2
SUBB A, Rn Subt ra ct re gis ter fro m A with borr ow 1 1
SUBB A, direct Subtract direct byte from A with borrow 2 2
SUBB A, @Ri Subtract indirect RAM from A with borrow 1 2
SUBB A, #data Subtract immedia te fro m A with borr ow 2 2
INC A Increment A 1 1
INC Rn Increment register 1 1
INC direct Increment direct byte 2 2
INC @Ri Increment indirect RAM 1 2
DEC A Decrement A 1 1
DEC Rn Decrement regis te r 1 1
DEC direct Decreme nt dir ec t byt e 2 2
DEC @Ri Decrement indirect RAM 1 2
INC DPTR Increment Data Pointer 1 1
MUL AB Multiply A and B 1 4
DIV AB Divide A by B 1 8
DA A Decimal adjust A 1 1
Logical Operations
ANL A, Rn AND Register to A 1 1
ANL A, direct AND direct byte to A 2 2
ANL A, @Ri AND indirect RAM to A 1 2
ANL A, #data AND immediate to A 2 2
ANL direct, A AND A to direct byte 2 2
ANL direct, #data AND immediate to direct byte 3 3
ORL A, Rn OR Register to A 1 1
ORL A, direct OR direct byte to A 22
Notes:
1. Assumes PFEN = 1 for all instruction timing.
2. MOVC instructions take 4 to 7 clock cycles depending on instruction alignment and the FLRT setting (SFR
Definition 16.3. FLSCL: Flash Scale).
C8051F410/1/2/3
96 Rev. 1.1
ORL A, @Ri OR indirect RAM to A 1 2
ORL A, #data OR immediate to A 2 2
ORL direct, A OR A to direct byte 2 2
ORL direct, #d ata OR immediate to direct byte 3 3
XRL A, Rn Exclusive-OR Register to A 1 1
XRL A, direct Exclusive-OR dire ct by te to A 2 2
XRL A, @Ri Exclusive-OR indirect RAM to A 1 2
XRL A, #data Exclusive-OR immediate to A 2 2
XRL direct, A Exclusive-OR A to direct byte 2 2
XRL direct, #data Exclusive-OR immediate to direct byte 3 3
CLR A Clear A 1 1
CPL A Complement A 1 1
RL A Ro tat e A l eft 1 1
RLC A Rotate A left through Ca rry 1 1
RR A Rotate A right 1 1
RRC A Rotate A right through Carry 1 1
SWAP A Swap nibbles of A 1 1
Data Transfer
MOV A, Rn Move Register to A 1 1
MOV A, direct Move direct byte to A 2 2
MOV A, @Ri Move indirect RAM to A 1 2
MOV A, #data Move immediate to A 2 2
MOV Rn, A Move A to Register 1 1
MOV Rn, direct Move direct byte to Register 2 2
MOV Rn, #data Move immediate to Register 2 2
MOV direct, A Move A to direct byte 2 2
MOV direct, Rn Move Register to direct byte 2 2
MOV direct, direct Move direct byte to direct byte 3 3
MOV direct, @Ri Move indirect RAM to direct byte 2 2
MOV direct, #data Move immediate to direct byte 3 3
MOV @Ri, A Move A to indirect RAM 1 2
MOV @Ri, direct Move direct byte to indirect RAM 2 2
MOV @Ri, #data Move immediate to indirect RAM 2 2
MOV DPTR, #data16 Load DPTR with 16-bit constant 3 3
MOVC A, @A+DPTR Move code byte relative DPTR to A 14 to 72
MOVC A, @A+PC Move code byte relative PC to A 14 to 72
MOVX A, @Ri Move external data (8-bit address) to A 1 3
MOVX @Ri, A Move A to external da ta (8-bit address) 1 3
MOVX A, @DPTR Move external data (16-bit address) to A 1 3
MOVX @DPTR, A Move A to external data (16- bit address) 1 3
PUSH direct Push direct byte onto stack 2 2
Table 10.1. CIP-51 Instruction Set Summary1 (Continued)
Mnemonic Description Bytes Clock
Cycles
Notes:
1. Assumes PFEN = 1 for all instruction timing.
2. MOVC instructions take 4 to 7 clock cycles depending on instruction alignment and the FLRT setting (SFR
Definition 16.3. FLSCL: Flash Scale).
C8051F410/1/2/3
Rev. 1.1 97
POP direct Pop direct byte from stack 2 2
XCH A, Rn Exchange Register with A 1 1
XCH A, direct Exchange direct byte with A 2 2
XCH A, @Ri Exchange indirect RAM with A 1 2
XCHD A, @Ri Exchange low nibble of indirect RAM with A 1 2
Boolean Manipulation
CLR C Clear Carry 1 1
CLR bit Clear direct bit 2 2
SETB C Set Carry 1 1
SETB bit Set direct bit 2 2
CPL C Complement Carry 1 1
CPL bit Complement direct bit 2 2
ANL C, bit AND direct bit to Carry 2 2
ANL C, /bit AND complement of direct bit to Carry 2 2
ORL C, bit OR direct bit to carry 2 2
ORL C, /bit OR complement of direct bit to Carry 2 2
MOV C, bit Move direct bit to Carry 2 2
MOV bit, C Move Carry to direct bi t 2 2
JC rel Jump if Carry is set 22/4
JNC rel Jump if Carry is not set 22/4
JB bit, rel Jump if direct bit is set 33/5
JNB bit, rel Jump if direct bit is not set 33/5
JBC bit, rel Jump if direct bit is set and clear bit 33/5
Program Branching
ACALL addr11 Absolute subroutine call 2 4
LCALL addr16 Long subroutine call 3 5
RET Return from subroutine 1 6
RETI Return from interrupt 1 6
AJMP addr11 Absolute jump 2 4
LJMP addr16 Long jump 3 5
SJMP rel Short jump (relative address) 2 4
JMP @A+DPTR Jump indirect relative to DPTR 1 4
JZ rel Jump if A equals zero 22/4
JNZ rel Jump if A does not equal zero 22/4
CJNE A, direct, rel Compare direct byte to A and jump if not equal 33/5
CJNE A, #data, rel Compare immediate to A and jump if not equal 33/5
CJNE Rn, #data, rel Compare immediate to Register and jump if not equal 33/5
CJNE @Ri, #data, re l Compare immediate to indirect and jump if not equal 34/6
DJNZ Rn, rel Decrement Register and jump if not zero 22/4
DJNZ direct, rel Decrement direc t byte and jump if not zero 33/5
NOP No operation 1 1
Table 10.1. CIP-51 Instruction Set Summary1 (Continued)
Mnemonic Description Bytes Clock
Cycles
Notes:
1. Assumes PFEN = 1 for all instruction timing.
2. MOVC instructions take 4 to 7 clock cycles depending on instruction alignment and the FLRT setting (SFR
Definition 16.3. FLSCL: Flash Scale).
C8051F410/1/2/3
98 Rev. 1.1
10.2. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic 1. Future product versions may use these bits to implement new features in
which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descrip-
tions of the remaining SF Rs are included in the se ctions of the datasheet associated with their correspond-
ing system function.
SFR Definition 10.1. SP: St ack Pointer
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) of fset 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 (0 x00-
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
2K-byte page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by L CALL and LJMP. The destination may be anywhere within
the 8K-byte program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
Bits7–0: SP: Stack Pointer.
The S tack 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.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x81
C8051F410/1/2/3
Rev. 1.1 99
SFR Definition 10.2. DPL: Data Pointer Low Byte
SFR Definition 10.3. DPH: Data Pointer High Byte
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x82
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x83
C8051F410/1/2/3
100 Rev. 1.1
SFR Definition 10.4. PSW: Program Status Word
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 0 by all other arithmetic operations.
Bit6: AC: Auxiliary Carry Flag
This bit is set when the last a rithmetic operation resu lted in a carry into (addition) or a borrow
from (subtraction) the hig h order nibble. It is cleared to 0 by all othe r ar ith me tic ope ra 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.
Bit2: OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 b y the ADD, ADDC, SUBB, MUL, a nd DIV instruction s i n all other
cases.
Bit1: F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
Bit0: PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulato r is odd and cleared if the sum
is even.
R/W R/W R/W R/W R/W R/W R/W R Reset Value
CY AC F0 RS1 RS0 OV F1 PARITY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xD0
RS1 RS0 Register Bank Address
0 0 0 0x00–0x07
0 1 1 0x08–0x0F
1 0 2 0x10–0x17
1 1 3 0x18–0x1F
C8051F410/1/2/3
Rev. 1.1 101
SFR Definition 10.5. ACC: Accumulator
SFR Definition 10.6. B: B Register
10.3. 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 internal clocks active. In Stop mode, the CPU is halted, all
interrupt s and timers (except the Missing Clock Detector ) are inactive, and the internal oscillator is stopped
(analog peripherals remain in their selected states; the external oscillator is not affected). 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 Defini-
tion 10.7 describes the Power Control Register (PCON) used to control the CIP-51's power management
modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital
peripherals, such as timers or serial buses, draw little power wh en they are not in use. T urning of f the oscil -
lators lowers power consumption consider ably; however a reset is required to restart the MCU.
The C8051F41x devices feature a low-power SUSPEND mode, which stops the internal oscillator until a
wakening event occurs. See Section “19.1.1. Internal Oscillator Suspend Mode” on page 166.
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xE0
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
B.7 B.6 B.5 B.4 B.3 B.2 B.1 B.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xF0
C8051F410/1/2/3
102 Rev. 1.1
10.3.1. 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 dat a. 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 watch dog reset and ther eby termi -
nate the Idle mode. This featur e protect s the system from an unintended per manent sh ut down in the event
of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by
software p rior to ente ring th e Idle mode if the WDT was ini tially configure d 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.
10.3.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to e nter Stop mode as soon as the instruc -
tion that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripher-
als 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 be gin s pr og ra m execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Dete ctor should be disa bled if the CPU is to be pu t to in ST OP mode for long er than th e
MCD timeout period of 100 μs.
10.3.3. Suspend Mode
The C8051F41x devices feature a low-power SUSPEND mode, which stops the internal oscillator until a
wakening event occurs. See Section “19.1.1. Internal Oscillator Suspend Mode” on page 166.
SFR Definition 10.7. PCON: Power Control
Bits7–2: Reserved.
Bit1: ST OP: STOP Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into STOP mode. This bit will always read ‘0’.
1: CIP-51 forced into power-down mode. (Turns off internal oscillator).
Bit0: IDLE: IDLE Mode Select.
Writin g a ‘1’ to this bit will place the CIP-51 into IDLE mode. This bit will always read ‘0’.
1: CIP-51 forced into IDLE mode. (Shuts off clock to CPU, but clock to Timers, Interrupts,
and all peripherals remain active.)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Reserved Reserved Reserved Reserved Reserved Reserved STOP IDLE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x87
C8051F410/1/2/3
Rev. 1.1 103
11. Memory Organization and SFRs
The memory organization of the C8051F41x 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 ar e accessed via different instruction types. The memory map is shown in Figure 11.1.
Figure 11.1. Memory Map
11.1. Program Memory
The CIP-51 core has a 64k-byte program memory space. The C8051F410/1 implement 32k of this pro-
gram memory space as in-system, re-programmable Flash memory, organized in a contiguous block from
addresses 0x0000 to 0x7DFF. Addresses above 0x7DFF are reserved on the 32 kB devices. The
C8051F412/3 implemen t 16 kB of Flash from addresses 0x0000 to 0x3FFF.
Program memory is normally assumed to be read-only. However, the C8051F41x can write to program
memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX write instruction.
This feature provides a mechanism for updates to program code and use of the program memory sp ace for
non-volatile data storage. Refer to Section “16. Flash Memory” on page 135 for further details.
PROGRAM/DATA MEMORY
(Flash)
(Direct and Indirect
Addressing)
0x00
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
0x80
0xFF Special Function
Register's
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
0x1F
0x20
0x2F Bit Addressable
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 2048 Bytes
(accessible using M OVX
instruction)
0x0000
0x07FF
Same 20 48 by tes a s from
0x0000 to 0x07FF, wrappe d
on 2048-byte boundaries
0x0800
0xFFFF
32 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x0000
RESERVED
0x7E00
0x7DFF
‘F410/1
16 kB Flash
(In -Sy stem
Programmable in 512
Byte Sectors)
0x0000
RESERVED
0x4000
0x3FFF
‘F412/3
C8051F410/1/2/3
104 Rev. 1.1
11.2. Data Memory
The C8051F41x includes 256 bytes of internal RAM mapped into the data memory space from 0x00
through 0xFF. The lower 128 bytes of data memor y are used for general purpo se registers and scr atch pad
memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory.
Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank con-
sisting 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 (SFRs) 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 11.1 illustrates the data memory organization of the C8051F41x.
The C8051F41x family also includes 2048 bytes of on-chip RAM mapped into the external memory
(XDATA) space. This RAM can be accessed using the CIP-51 core’s MOVX instruction. More information
on the XRAM memory can be found in Section “17. External RAM” on page 145.
11.3. General Purpose Registers
The lower 32 bytes of data memory (locations 0x00 through 0x1F) may be addressed as four banks of
general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7.
Only one of these banks may be enabled at a time. Two bit s in th e progr am st atus word , RS0 (PSW.3) and
RS1 (PSW.4), select the active register bank (see description of the PSW in SFR Definition 10.4. PSW:
Program Status Word). This allows fast context switching when entering subroutines and interrupt service
routines. Indirect addressing modes use registers R0 and R1 as inde x registers.
11.4. 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 h as bit add ress 0x00 while b it 7 of the byte at 0x 20 has bit a ddress
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destination).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
11.5. 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 re gister 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 st a ck depth ca n exte nd up
to 256 bytes.
C8051F410/1/2/3
Rev. 1.1 105
11.6. 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 11.1 lists the SFRs
implemented in the CIP- 51 Syste m Co nt ro ller.
The SFR regist ers are acc essed anytime the direct a ddressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, IE, etc.) are bit-a ddressable
as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR
space are reserved for fut ure use. Accessin g these areas will hav e an indeterminat e effect and should be
avoided. Refer to the corresponding pages of the data sheet, as indicated in Table 11.2, for a detailed
description of ea ch regi st er.
Table 11.1. Special Function Register (SFR) Memory Map
F8 SPI0CN PCA0L PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 PCA0CPH4 VDM0CN
F0 BP0MDIN P1MDIN P2MDIN IDA1L IDA1H EIP1 EIP2
E8 ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 RSTSRC
E0 ACC XBR0 XBR1 PFE0CN IT01CF EIE1 EIE2
D8 PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 CRC0FLIP
D0 PSW REF0CN PCA0CPL5 PCA0CPH5 P0SKIP P1SKIP P2SKIP P0MAT
C8 TMR2CN REG0CN TMR2RLL TMR2RLH TMR2L TMR2H PCA0CPM5 P1MAT
C0 SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH P0MASK
B8 IP IDA0CN ADC0TK ADC0MX ADC0CF ADC0L ADC0H P1MASK
B0 P0ODEN OSCXCN OSCICN OSCICL IDA1CN FLSCL FLKEY
A8 IE CLKSEL EMI0CN CLKMUL RTC0ADR RTC0DAT RTC0KEY ONESHOT
A0 P2 SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT
98 SCON0 SBUF0 CPT1CN CPT0CN CPT1MD CPT0MD CPT1MX CPT0MX
90 P1 TMR3CN TMR3RLL TMR3RLH TMR3L TMR3H IDA0L IDA0H
88 TCON TMOD TL0 TL1 TH0 TH1 CKCON PSCTL
80 P0 SP DPL DPH CRC0CN CRC0IN CRC0DAT PCON
0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F)
(bit addressable)
C8051F410/1/2/3
106 Rev. 1.1
Table 11.2. Special Function Registers
SFRs are listed in alphabetical order. All undefin ed SFR locations are reserved.
Register Address Description Page
ACC 0xE0 Accumulator 101
ADC0CF 0xBC ADC0 Configuration 60
ADC0CN 0xE8 ADC0 Control 62
ADC0H 0xBE ADC0 61
ADC0L 0xBD ADC0 61
ADC0GTH 0xC4 ADC0 Greater-Than Data High Byte 64
ADC0GTL 0xC3 ADC0 Greater-Than Data Low Byte 64
ADC0LTH 0xC6 ADC0 Less-Than Data High Byte 65
ADC0LTL 0xC5 ADC0 Less-Than Data Low Byte 65
ADC0MX 0xC6 ADC0 Channel Select 59
ADC0TK 0xBA ADC0 Tracking Mode Select 63
B0xF0B Register 101
CKCON 0x8E Clock Control 237
CLKMUL 0xAB Clock Multiplier 173
CLKSEL 0xA9 Clock Select 174
CPT0CN 0x9B Comparator0 Control 86
CPT0MD 0x9D Comparator0 Mode Selection 88
CPT0MX 0x9F Comparator0 MUX Selection 87
CPT1CN 0x9A Comparator1 Control 91
CPT1MD 0x9C Comparator1 Mode Selection 90
CPT1MX 0x9E Comparator1 MUX Selection 89
CRC0CN 0x84 CRC0 Control 125
CRC0IN 0x85 CRC0 Data Input 125
CRC0DAT 0x86 CRC0 Data Output 126
CRC0FLIP 0xDF CRC0 Bit Flip 126
DPH 0x83 Data Pointer High 99
DPL 0x82 Data Pointer Low 99
EIE1 0xE6 Extended Interrupt Enable 1 114
EIE2 0xE7 Extended Interrupt Enable 2 116
EIP1 0xF6 Extended Interrupt Priority 1 115
EIP2 0xF7 Extended Interrupt Priority 2 116
EMI0CN 0xAA External Memory Interface Control 145
FLKEY 0xB7 Flash Lock and Key 141
FLSCL 0xB6 Flash Scale 142
IDA0H 0x97 Current Mode DAC0 High Byte 71
IDA0L 0x96 Current Mode DAC0 Low Byte 72
IDA0CN 0xB9 Current Mode DAC0 Control 71
IDA1H 0xF5 Current Mode DAC1 High Byte 73
C8051F410/1/2/3
Rev. 1.1 107
IDA1L 0xF4 Current Mode DAC1 Low Byte 73
IDA1CN 0xB5 Current Mode DAC1 Control 72
IE 0xA8 Interrupt Enable 112
IP 0xB8 Interrupt Priority 113
IT01CF 0xE4 INT0/INT1 Con figuration 118
ONESHOT 0xAF Flash Oneshot Period 143
OSCICL 0xB3 Internal Oscillator Calibration 167
OSCICN 0xB2 Internal Oscillator Control 167
OSCXCN 0xB1 External Oscillat or Con trol 171
P0 0x80 Port 0 Latch 155
P0MASK 0xC7 Port 0 Mask 157
P0MAT 0xD7 Port 0 Match 157
P0MDIN 0xF1 Port 0 Input Mode Configuration 155
P0MDOUT 0xA4 Port 0 Output Mode Configuration 156
P0ODEN 0xB0 Port 0 Overdrive 157
P0SKIP 0xD4 Port 0 Skip 156
P1 0x90 Port 1 Latch 158
P1MASK 0xBF Port 1 Mask 160
P1MAT 0xCF Port 1 Match 160
P1MDIN 0xF2 Port 1 Input Mode Configuration 158
P1MDOUT 0xA5 Port 1 Output Mode Configuration 159
P1SKIP 0xD5 Port 1 Skip 159
P2 0xA0 Port 2 Latch 161
P2MDIN 0xF3 Port 2 Input Mode Configuration 161
P2MDOUT 0xA6 Port 2 Output Mode Configuration 162
P2SKIP 0xD6 Port 2 Skip 162
PCA0CN 0xD8 PCA Control 261
PCA0CPH0 0xFC PCA Capture 0 High 264
PCA0CPH1 0xEA PCA Capture 1 High 264
PCA0CPH2 0xEC PCA Capture 2 High 264
PCA0CPH3 0xEE PCA Capture 3 High 264
PCA0CPH4 0xFE PCA Capture 4 High 264
PCA0CPH5 0xD3 PCA Capture 5 High 264
PCA0CPL0 0xFB PCA Capture 0 Low 264
PCA0CPL1 0xE9 PCA Capture 1 Low 264
PCA0CPL2 0xEB PCA Capture 2 Low 264
PCA0CPL3 0xED PCA Capture 3 Low 264
PCA0CPL4 0xFD PCA Capture 4 Low 264
Table 11.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefin ed SFR locations are reserved.
Register Address Description Page
C8051F410/1/2/3
108 Rev. 1.1
PCA0CPL5 0xD2 PCA Capture 5 Low 264
PCA0CPM0 0xDA PCA Module 0 Mode 263
PCA0CPM1 0xDB PCA Module 1 Mode 263
PCA0CPM2 0xDC PCA Module 2 Mode 263
PCA0CPM3 0xDD PCA Module 3 Mode 263
PCA0CPM4 0xDE PCA Module 4 Mode 263
PCA0CPM5 0xCE PCA Module 5 Mode 263
PCA0H 0xFA PCA Counter High 264
PCA0L 0xF9 PCA Counter Low 264
PCA0MD 0xD9 PCA Mode 262
PCON 0x87 Power Control 102
PFE0CN 0xE3 Prefetch Engine Control 119
PSCTL 0x8F Program St or e R/W Co nt ro l 141
PSW 0xD0 Program Status Word 100
REF0CN 0xD1 Voltage Reference Control 78
REG0CN 0xC9 Voltage Regulator Control 82
RTC0ADR 0xAC smaRTClock Address 181
RTC0DAT 0xAD smaRTClock Data 182
RTC0KEY 0xAE smaRTClock Lock and Key 180
RSTSRC 0xEF Reset Source Co nf ig u ra tion/Status 133
SBUF0 0x99 UART0 Data Buffer 213
SCON0 0x98 UART0 Control 212
SMB0CF 0xC1 SMBus Configuration 197
SMB0CN 0xC0 SMBus Control 199
SMB0DAT 0xC2 SMBus Data 201
SP 0x81 Stack Pointer 98
SPI0CFG 0xA1 SPI Configuration 223
SPI0CKR 0xA2 SPI Clock Rate Control 225
SPI0CN 0xF8 SPI Control 224
SPI0DAT 0xA3 SPI Data 226
TCON 0x88 Timer/Counter Control 235
TH0 0x8C Timer/Counter 0 High 238
TH1 0x8D Timer/Counter 1 High 238
TL0 0x8A Timer/Counter 0 Low 238
TL1 0x8B Timer/Counter 1 Low 238
TMOD 0x89 Timer/Counter Mode 236
TMR2CN 0xC8 Timer/Counter 2 Control 242
TMR2H 0xCD Ti mer/Counter 2 High 243
Table 11.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefin ed SFR locations are reserved.
Register Address Description Page
C8051F410/1/2/3
Rev. 1.1 109
TMR2L 0xCC Timer/Counter 2 Low 243
TMR2RLH 0xCB Timer/Counter 2 Reload High 243
TMR2RLL 0xCA Timer/Counte r 2 Reload Lo w 243
TMR3CN 0x91 Timer/Counter 3Control 247
TMR3H 0x95 Timer/Counter 3 High 248
TMR3L 0x94 Timer/Counter 3 Low 248
TMR3RLH 0x93 Timer/Counter 3 Reload High 248
TMR3RLL 0x92 Timer/Counter 3 Reload Lo w 248
VDM0CN 0xFF VDD Monitor Control 130
XBR0 0xE1 Port I/O Crossbar Control 0 153
XBR1 0xE2 Port I/O Crossbar Control 1 154
Table 11.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefin ed SFR locations are reserved.
Register Address Description Page
C8051F410/1/2/3
110 Rev. 1.1
12. Interrupt Handler
The C8051F41x family includes an extended interrupt system supporting a total of 18 interrupt sources
with two prior ity levels. Th e allocation of interrupt sour ces between on -chip peripher als and extern al input
pins varies according to the specific version of the device. Each interrupt source has one or more associ-
ated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid inter-
rupt condition, the associated interrupt-pending flag is set to logic 1.
If interrupt s are ena bled for the sour ce, an interrupt request is gener ated when the interru pt-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 executio n of an interrupt service ro utine (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 requ est had not occurred. If inter rupt s are not enabled, the inter rupt-pending fla g 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 the Interrupt Enable and Extended Interrupt Enable SFRs. However, interrupts must first be
globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recog-
nized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-
enable settings. Note that interrupts which occur when the EA bit is set to logic 0 will be held in a pending
state, and will not be serviced until the EA bit is set back to logic 1.
Some interrupt-pending flags ar e auto matically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cle ared by the har dware a nd must b e clear ed by so ftware before retur ning fro m 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.
12.1. MCU Interrupt Sources and Vectors
The MCUs support 18 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 vec tor addr esses, pr iority or der, and control bits are summarized in Table 12.1 on page 111. Refer to
the data sheet sec tion associated w ith a particular on-c hip peripheral f or informatio n regarding va lid inter -
rupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
12.2. Interrupt Priorities
Each interrupt source can be in dividua lly prog ra mmed to on e o f two p riority levels: lo w or h igh. A low prior-
ity interrupt service routine can be preempted by a high priority interrupt. A high priority inte rrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure
its priori ty level. Low priority is th e default. If two interru pts are re cognized simult aneously, 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 12.1.
12.3. 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 7
system clock c ycles: 1 clock cycle to detect the interrupt, 1 clock cycle to execute a singl e instruction, and
5 clock cycl es t o co mpl ete t he L CALL to th e I SR. If an in ter rupt is pend ing when a RET I i s ex ecut ed, a sin -
gle instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maxi-
mum 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
C8051F410/1/2/3
Rev. 1.1 111
instruction. In this case, the response time is 19 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 5 clock cy cles to e xe-
cute 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 instruc-
tion.
Table 12.1. Interrupt Summary
Interrupt Source Interrupt
Vector Priority
Order Pending Flag
Bit addressable?
Cleared by HW?
Enable
Flag Priority
Control
Reset 0x0000 Top None N/A N/A Always
Enabled Always
Highest
External Interrupt 0 (/INT0) 0x0003 0IE0 (TCON.1) Y Y EX0 (IE.0) PX0 (IP.0)
Timer 0 Overflow 0x000B 1TF0 (TCON.5) Y Y ET0 (IE.1) PT0 (IP.1)
External Interrupt 1 (/INT1) 0x0013 2IE1 (TCON.3) Y Y EX1 (IE.2) PX1 (IP.2)
Timer 1 Overflow 0x001B 3TF1 (TCON.7) Y Y ET1 (IE.3) PT1 (IP.3)
UART0 0x0023 4RI0 (SCON0.0)
TI0 (SCON0.1) Y N ES0 (IE.4) PS0 (IP.4)
Timer 2 Overflow 0x002B 5TF2H (TMR2CN.7)
TF2L (TMR2CN.6) Y N ET2 (IE.5) PT2 (IP.5)
SPI0 0x0033 6
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
Y N ESPI0
(IE.6)PSPI0
(IP.6)
SMB0 0x003B 7SI (SMB0CN.0) Y N ESMB0
(EIE1.0) PSMB0
(EIP1.0)
smaRTClock 0x0043 8ALRM (RTC0CN.2)
OSCFAIL
(RTC0CN.5) N N ERTC0
(EIE1.1) PRTC0
(EIP1.1)
ADC0 Window
Comparator 0x004B 9AD0WINT
(ADC0CN.3) Y N EWADC0
(EIE1.2) PWADC0
(EIP1.2)
ADC0 End of Conversion 0x0053 10 AD0INT (ADC0STA.5) Y N EADC0
(EIE1.3) PADC0
(EIP1.3)
Programm abl e Co un te r
Array 0x005B 11 CF (PCA0CN.7)
CCFn (PCA0CN.n) Y N EPCA0
(EIE1.4) PPCA0
(EIP1.4)
Comparator0 0x0063 12 CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5) N N ECP0
(EIE1.5) PCP0
(EIP1.5)
Comparator1 0x006B 13 CP1FIF (CPT1CN.4)
CP1RIF (CPT1CN.5) N N ECP1
(EIE1.6) PCP1
(EIP1.6)
Timer 3 Overflow 0x0073 14 TF3H (TMR3CN.7)
TF3L (TMR3CN.6) N N ET3
(EIE1.7) PT3
(EIP1.7)
Voltage Regulator Dropout 0x007B 15 N/A N/A N/A EREG0
(EIE2.0) PREG0
(EIP2.0)
Port Match 0x0083 16 N/A N/A N/A EMAT
(EIE2.1) PMAT
(EIP2.1)
C8051F410/1/2/3
112 Rev. 1.1
12.4. Interrupt Register Descriptions
The SFRs used to enable th e inte rrupt sources an d set their pr iority le vel ar e descri bed below. Refer to the
data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for th e pe riph er al an d th e be ha vio r of its interrupt-p en din g flag (s) .
SFR Definition 12.1. IE: Interrupt Enable
Bit 7: EA: Global Interrupt Enable.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask set-
tings.
0: Disable all interrupt sour ce s.
1: Enable each interrupt according to its individual mask setting.
Bit 6: ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrup ts.
1: Enable interrupt requests generated by SPI0.
Bit 5: ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt reque sts generated by the TF2L or TF2H flags.
Bit 4: ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
Bit 3: 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.
Bit 2: EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable exte rn al inte r ru pt 1.
1: Enable interrupt requests generated by the /INT1 input.
Bit 1: ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
Bit 0: EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable exte rn al inte r ru pt 0.
1: Enable interrupt requests generated by the /INT0 input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EA ESPI0 ET2 ES0 ET1 EX1 ET0 EX0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xA8
C8051F410/1/2/3
Rev. 1.1 113
SFR Definition 12.2. IP: Interrupt Priority
Bit 7: UNUSED. Read = 1, Write = don't care.
Bit 6: PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
Bit 5: PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 inter ru pt set to low priority level.
1: Timer 2 inter ru pt set to high priority level.
Bit 4: 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.
Bit 3: PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 inter ru pt set to low priority level.
1: Timer 1 inter ru pt set to high priority level.
Bit 2: PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External In terrupt 1 set to low priority level.
1: External In terrupt 1 set to high p riority level.
Bit 1: PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 inter ru pt set to low priority level.
1: Timer 0 inter ru pt set to high priority level.
Bit 0: PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External In terrupt 0 set to low priority level.
1: External In terrupt 0 set to high p riority level.
R R/W R/W R/W R/W R/W R/W R/W Reset Value
- PSPI0 PT2 PS0 PT1 PX1 PT0 PX0 10000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xB8
C8051F410/1/2/3
114 Rev. 1.1
SFR Definition 12.3. EIE1: Extended Interrupt Enable 1
Bit 7: ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt reque sts generated by the TF3L or TF3H flags.
Bit 6: ECP1: Enable Comparator 1 (CP1) Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 interrupts.
1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags.
Bit 5: ECP0: Enable Comparator 0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags.
Bit 4: EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrup ts.
1: Enable interrupt requests generated by PCA0.
Bit 3: EADC0: Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
Bit 2: EWADC0: Enable ADC0 Window Comparison Interrupt.
This bit sets the masking of the ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by the AD0WINT flag.
Bit 1: ERTC0: Enable smaRTClock Interrupt.
This bit sets the masking of the smaRTClock interrupt.
0: Disable smaRTClock interrupts.
1: Enable interrupt requests generated by the ALRM and OSCFAIL flag.
Bit 0: ESMB0: Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 inter ru pts.
1: Enable interrupt requests generated by SMB0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ET3 ECP1 ECP0 EPCA0 EADC0 EWADC0 ERTC0 ESMB0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE6
C8051F410/1/2/3
Rev. 1.1 115
SFR Definition 12.4. EIP1: Extended Interrupt Priority 1
Bit 7: PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
Bit 6: PCP1: Comparator1 (CP1) Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 interrupt set to low priority level.
1: CP1 interrupt set to high priority level.
Bit 5: PCP0: Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
Bit 4: 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.
Bit 3: PADC0: ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
Bit 2: PWADC0: ADC0 Window Compar ison Interrupt Priority Control.
This bit sets the priority of the ADC0 Window Comparison interrupt.
0: ADC0 Window Comparison interrupt set to low priority level.
1: ADC0 Window Comparison interrupt set to high priority level.
Bit 1: PRTC0: smaRTClock Interrupt Priority Contro l.
This bit sets the priority of the smaRTClock interrupt.
0: smaRTClock interrupt set to low priority level.
1: smaRTClock interrupt set to high priority level.
Bit 0: PSMB0: SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PT3 PCP1 PCP0 PPCA0 PADC0 PWADC0 PRTC0 PSMB0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF6
C8051F410/1/2/3
116 Rev. 1.1
SFR Definition 12.5. EIE2: Extended Interrupt Enable 2
SFR Definition 12.6. EIP2: Extended Interrupt Priority 2
Bits 7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit 1: EMAT: Enable Port Match Interrupt.
This bit sets the masking of the Port Match interrupt.
0: Disable the Port Match interrupt.
1: Enable the Port Match interrupt.
Bit 0: EREG0: Enable Voltage Regulator Interrupt.
This bit sets the masking of the Voltage Regulator Dropout inte rrupt.
0: Disable the Voltage Regulator Dropout interrupt.
1: Enable the Voltage Regulator Dropout interrupt.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
------EMATEREG000000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE7
Bits 7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit 1: EMAT: Port Match Interrupt Priority Control.
This bit sets the priority of the Port Match interrupt.
0: Port Match interrupt set to low priority level.
1: Port Match interrupt set to high priority level.
Bit 0: PREG0: Voltage Regulator Interrupt Priority Control.
This bit sets the priority of the Voltage Regulator interrupt.
0: Voltage Regulator interrupt set to low priority level.
1: Voltage Regulator interrupt set to high priority level.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
------PMATPREG000000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF7
C8051F410/1/2/3
Rev. 1.1 117
12.5. 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 IT 1 bits in TCON (Section “24.1. Timer 0 and Timer 1” on page 231) select level
or edge sensitive. The table below lists the possible configurations.
/INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 12.7).
Note that /INT0 and /INT0 Port pin assignments are independent of any Crossbar assignments. /INT0 and
/INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin
via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the
selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section
“18.1. Priority Crossbar Decoder” on page 149 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 interrup t-pending flag is automatically cle ared by th e 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.
IT0 IN0PL /INT0 Interrupt IT1 IN1PL /INT1 Interrupt
10Active low, edge sensitive 10A ctive low, edge sensitive
11Active high, edge sensitive 11Active high, edge sensitive
00Active low, level sensitive 00A ctive low, level sensitive
01Active high, level sensitive 01Active high, level sensitive
C8051F410/1/2/3
118 Rev. 1.1
SFR Definition 12.7. IT01CF: INT0/INT1 Configuration
Bit 7: IN1PL: /INT1 Polarity
0: /INT1 input is active low.
1: /INT1 input is active high.
Bits 6–4: 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 configu red to skip the selected pin (accomplishe d by
setting to ‘1’ the corresponding bit in register P0SKIP).
Bit 3: IN0PL: /INT0 Polarity
0: /INT0 interrupt is active low.
1: /INT0 interrupt is active high.
Bits 2–0: 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 pi n 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 configu red to skip the selected pin (accomplishe d by
setting to ‘1’ the corresponding bit in register P0SKIP).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
IN1PL IN1SL2 IN1SL1 IN1SL0 IN0PL IN0SL2 IN0SL1 IN0SL0 00000001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE4
Note: Refer to SFR Definition 24.1. “TCON: Timer Control” on page 235 for INT0/1 edge- or level-sensitive interrupt selection.
IN1SL2–0 /INT1 Port Pin
000 P0.0
001 P0.1
010 P0.2
011 P0.3
100 P0.4
101 P0.5
110 P0.6
111 P0.7
IN0SL2–0 /INT0 Port Pin
000 P0.0
001 P0.1
010 P0.2
011 P0.3
100 P0.4
101 P0.5
110 P0.6
111 P0.7
C8051F410/1/2/3
Rev. 1.1 119
13. Prefetch Engine
The C8051F41x family of devices incorporate a 2-byte prefetch engine. Due to Flash access time specifi-
cations, the prefetch engine is necessary for full-speed (50 MHz) code execution. Instructions are read
from Flas h memo ry t wo byte s at a time b y the pref etch engine, and given to the CIP-51 processor core to
execute. When running linear code (code without any jumps or branches), the prefetch engine allows
instructions to be executed at full speed. When a code branch occurs, the processor may be stalled for up
to two clock cycles while the next set of code bytes is retrieved from Flash memory. The FLRT bit
(FLSCL.4) determines how many clock cycles are used to read each set of two code bytes from Flash.
When operating from a system clock of 25 MHz or less, the FLRT bit should be set to ‘0’ so that the
prefetch engine takes only one clock cycle for ea ch read. When operating with a system clock of greater
than 25 MHz (up to 50 MHz), the FLRT bit should be set to ‘1’, so that each prefetch code read lasts for
two clock cycles.
SFR Definition 13.1. PFE0CN: Prefetch Engine Control
Bits 7–6: Unused. Read = 00b; Write = Don’t Care
Bit 5: PFEN: Prefetch Enable.
This bit enables the pr ef etc h en g i ne.
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bits 4–1: Unused. Read = 0000b; Write = Don’t Care
Bit 0: FLBWE: Flash Block Write Enable.
This bit allows block writes to Flash memory from software.
0: Each byte of a software Flash write is written individually.
1: Flash bytes are written in groups of two.
Note: The prefetch engine should be disabled when changes to FLRT are made. See Section
“16. Flash Memory” on page 135.
R R R/W R R R R R/W Reset Value
PFEN FLBWE 00100000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE3
C8051F410/1/2/3
120 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 121
14. Cyclic Redundancy Check Unit (CRC0)
C8051F41x devices include a cyclic redundancy check unit (CRC0) that can perform a CRC using a 16-bit
or 32-bit polynomial. CRC0 accepts a stream of 8-bit data written to the CRC0IN register. CRC0 posts the
16-bit or 32-bit result to an internal register. The internal result register may be accessed indirectly using
the CRC0PNT bits and CRC0DAT register, as shown in Figure 14.1. CRC0 also has a bit reverse register
for quick data manipulatio n.
Figure 14.1. CRC0 Block Diagram
14.1. 16-bit CRC Algorithm
The C8051F41x CRC unit calculates the 16-bit CRC MSB-first, using a poly of 0x1021. The following
describes the 16 -b it CRC algo rith m per form e d by th e ha rd wa re :
Step 1. XOR the most-significant byte of the current CRC result with the input byte. If this is the
first iteration of the CRC unit, th e current CRC result will be the set initia l value (0x0000 or
0xFFFF).
Step 2a. If the MSB of the CRC result is set, left-shift the CRC result, and then XOR the CRC
result with the polynomial (0x1021).
Step 2b. If the MSB of the CRC result is not set, left-shift the CRC result.
Step 3. Repeat at Step 2a for the number of input bits (8).
CRC0IN 8
CRC0DAT
CRC0CN
CRC0SEL
CRC0INIT
CRC0VAL
CRC0PNT1
CRC0PNT0
CRC Engine
4 to 1 MUX
RESULT
32
8 8 8 8
8
C8051F410/1/2/3
122 Rev. 1.1
For example, the 16-bit 'F41x CRC algorithm can be described by the following code:
unsigned short UpdateCRC (unsigned short CRC_acc, unsigned char CRC_input)
{
unsigned char i; // loop counter
#define POLY 0x1021
// Create the CRC "dividend" for polynomial arithmetic (binary arithmetic
// with no carries)
CRC_acc = CRC_acc ^ (CRC_input << 8);
// "Divide" the poly into the dividend using CRC XOR subtraction
// CRC_acc holds the "remainder" of each divide
//
// Only complete this division for 8 bits since input is 1 byte
for (i = 0; i < 8; i++)
{
// Check if the MSB is set (if MSB is 1, then the POLY can "divide"
// into the "dividend")
if ((CRC_acc & 0x8000) == 0x8000)
{
// if so, shift the CRC value, and XOR "subtract" the poly
CRC_acc = CRC_acc << 1;
CRC_acc ^= POLY;
}
else
{
// if not, just shift the CRC value
CRC_acc = CRC_acc << 1;
}
}
// Return the final remainder (CRC value)
return CRC_acc;
}
The following table lists several input values and the associated outputs using the 16-bit 'F41x CRC algo-
rithm (an initial value of 0xFFFF is used) :
Table 14.1. Example 16-bit CRC Outputs
Input Output
0x63 0xBD35
0x8C 0xB1F4
0x7D 0x4ECA
0xAA, 0xBB, 0xCC 0x6CF6
0x00, 0x00, 0xAA, 0xBB, 0xCC 0xB166
C8051F410/1/2/3
Rev. 1.1 123
14.2. 32-bit CRC Algorithm
The C8051F41x CRC unit calculates the 32-bit CRC using a poly of 0x0 4C11DB7. The CRC-32 algorithm
is "reflected", meaning that all of the input bytes and the final 32-bit output are bit-reversed in the process-
ing engine. The following is a description of a simplified CRC algorithm that produces results identical to
the hardware :
Step 1. XOR the least-significant byte of the current CRC result with the input byte. If this is the
first iteration of the CRC unit, the current CRC result will be the set initial value
(0x00000000 or 0xFFFFFFFF).
Step 2. Right-shift the CRC result.
Step 3. If the LSB of the CRC result is set, XOR the CRC result with the reflected polynomial
(0xEDB88320).
Step 4. Repeat at Step 2 for the number of input bits (8).
For example, the 32-bit 'F41x CRC algorithm can be described by the following code:
unsigned long UpdateCRC (unsigned long CRC_acc, unsigned char CRC_input)
{
unsigned char i; // loop counter
#define POLY 0xEDB88320 // bit-reversed version of the poly 0x04C11DB7
// Create the CRC "dividend" for polynomial arithmetic (binary arithmetic
// with no carries)
CRC_acc = CRC_acc ^ CRC_input;
// "Divide" the poly into the dividend using CRC XOR subtraction
// CRC_acc holds the "remainder" of each divide
//
// Only complete this division for 8 bits since input is 1 byte
for (i = 0; i < 8; i++)
{
// Check if the MSB is set (if MSB is 1, then the POLY can "divide"
// into the "dividend")
if ((CRC_acc & 0x00000001) == 0x00000001)
{
// if so, shift the CRC value, and XOR "subtract" the poly
CRC_acc = CRC_acc >> 1;
CRC_acc ^= POLY;
}
else
{
// if not, just shift the CRC value
CRC_acc = CRC_acc >> 1;
}
}
// Return the final remainder (CRC value)
return CRC_acc;
}
The following table lists several input values and the associated outputs using the 32-bit 'F41x CRC algo-
rithm (an initial value of 0xFFFFFFFF is used):
C8051F410/1/2/3
124 Rev. 1.1
14.3. Preparing for a CRC Calculation
To prepare CRC0 for a CRC calculation, software should select the desired polynomial and set the initial
value of the result. Two polynomials are available: 0x1021 (16-bit) and 0x04C11DB7 (32-bit). The CRC0
result may be initialized to one of two values: 0x00000000 or 0xFFFFFFFF. The following steps can be
used to initialize CRC0.
Step 1. Select a polynomial (Set CRC0SEL to ‘0’ for 32-bit or ‘1’ for 16-bit).
Step 2. Select the initial result value (Set CRC0VAL to ‘0’ for 0x0000 000 0 or ‘1’ for 0xFFF FFFFF ).
Step 3. Set the result to its initial value (Write ‘1’ to CRC0INIT).
14.4. Performing a CRC Calculation
Once CRC0 is initialized, the input data stream is sequentially written to CRC0IN, one byte at a time. The
CRC0 result is automatically updated after each byte is written.
14.5. Accessing the CRC0 Result
The internal CRC0 result is 32-bits (CRC0SEL = 0b) or 16-bits (CRC0SEL = 1b). The CRC0PNT bits
select the byte that is t argeted by re ad and write opera tions on CRC0DAT and increment after e ach read or
write. The calculation result will remain in the internal CRC0 result register until it is set, overwritten, or
additional data is written to CRC0IN.
14.6. CRC0 Bit Reverse Feature
CRC0 includes hardware to reverse the bit order of each bit in a byte as shown in Figure 14.2. Each byte
of data written to CRC0FLIP is read back bit reversed. For example, if 0xC0 is written to CRC0FLIP, the
data read back is 0x03.
Figure 14.2. Bit Reverse Register
Table 14.2. Example 32-bit CRC Outputs
Input Output
0x63 0xF9462090
0xAA, 0xBB, 0xCC 0x41B207B3
0x00, 0x00, 0xAA, 0xBB, 0xCC 0x78D129BC
CRC0FLIP
Write
CRC0FLIP
Read
C8051F410/1/2/3
Rev. 1.1 125
SFR Definition 14.1. CRC0CN: CRC0 Control
SFR Definition 14.2. CRC0IN: CRC0 Data Input
Bits 7–5: UNUSED. Read = 0b. Write = don’t care.
Bit 4: CRC0SEL: CRC0 Polynomial Select Bit.
0: CRC0 uses the 32-bit polynomial 0x04C11DB7 for calculating the CRC result.
1: CRC0 uses the 16-bit polynomial 0x1021 for calculating the CRC result.
Bit 3: CRC0INIT: CRC0 Result Initialization Bit.
Writing a ‘1’ to this bit initializes the entire CRC result based on CRC0VAL.
Bit 2: CRC0VAL: CRC0 Set Value Select Bit
This bit selects the set value of the CRC result.
0: CRC result is set to 0x00000000 on write of ‘1’ to CRC0INIT.
1: CRC result is set to 0xFFFFFFFF on write of ‘1’ to CRC0INIT.
Bits 1–0: CRC0PNT. CRC0 Result Pointer.
These bits specify which byte of the CRC result will be read/written on the next access to
CRC0DAT. The value of these bits will auto-increment up on each read or write.
For CRC0SEL = 0:
00: CRC0DAT accesses bits 7–0 of the 32-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 32-bit CRC result.
10: CRC0DAT accesses bits 23–16 of the 32-bit CRC result.
11: CRC0DAT accesses bits 31–24 of the 32-bit CRC result.
For CRC0SEL = 1:
00: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
01: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
10: CRC0DAT accesses bits 7–0 of the 16-bit CRC result.
11: CRC0DAT accesses bits 15–8 of the 16-bit CRC result.
R R R R/W W R/W R/W R/W Reset Value
- - - CRC0SEL CRC0INIT CRC0VAL CRC0PNT 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x84
Bits 7–0: CRC0IN: CRC Data Input
Each write to CRCIN results in the written data being computed into the existing CRC result.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x85
C8051F410/1/2/3
126 Rev. 1.1
SFR Definition 14.3. CRC0DAT: CRC0 Data Output
SFR Definition 14.4. CRC0FLIP: CRC0 Bit Flip
Bits 7–0: CRC0DAT: Indirect CRC Result Data Bit s .
Each operation performed on CRC0DAT targets the CRC result bits pointed to by
CRC0PNT.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x86
Bits 7–0: CRC0FLIP: CRC Bit Flip.
Any byte written to CRC0FLIP is read back in a bit-reversed order, i.e. the written LSB
becomes the MSB. For example:
If 0xC0 is written to CRC0FLIP, the data read back will be 0x03.
If 0x05 is written to CRC0FLIP, the data read ba ck will be 0xA0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xDF
C8051F410/1/2/3
Rev. 1.1 127
15. 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 da ta on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled
during and after the reset. For VDD Monitor and power-on resets, the RST pin is driven low until the device
exits the re set 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 “19. Oscillators” on page 165 for information on se lecting and configurin g
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “25.3. Watchdog Timer Mode” on page 257 details the use of the Watchdog Timer).
Program execution begins at location 0x0000.
Figure 15.1. Reset Sources
PCA
WDT
Missing
Clock
Detector
(one-
shot) (Softw a re R e se t)
System Reset
Reset
Funnel
Px.x
Px.x
EN SWRSF
System
Clock CIP-51
Microcontroller
Core
Ex te n de d Inte rru p t
Handler
EN
WDT
Enable
MCD
Enable
Illegal Flash
Operation
/RST
(wired-OR)
Power On
Reset
'0'
+
-
Comparator 0
VDD
+
-
Supply
Monitor
Enable
smaRTClock RTC0RE
C0RSEF
C8051F410/1/2/3
128 Rev. 1.1
15.1. Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low until VDD settles above
VRST. An additional delay occurs before the device is released from reset; the delay decreases as the VDD
ramp time increases (VDD ramp time is de fined as how fa st VDD ramps from 0 V to VRST). Figure 15.2 plots
the power-on and VDD monitor reset timing. For valid ramp times (less than 1 ms), the power-on reset
delay (TPORDelay) is typically less than 0.3 ms.
Note: The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to be r eleased fro m
reset before VDD reaches the VRST level.
On exit from a power-on r eset, the PORSF fl ag (RSTSRC.1) is set by hardwar e 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 contents of internal data
memory should be assumed to be undefined after a power-on reset. The VDD monitor is en ab le d fo llo wing
a power-on res et .
Figure 15.2. Power-On and VDD Monitor Reset Timing
Power-On
Reset
VDD
Monitor
Reset
/RST
t
volts
1.0
Logic HIGH
Logic LO W TPORDelay
VDD
VRST
VDD
C8051F410/1/2/3
Rev. 1.1 129
15.2. Power-Fail Reset / VDD Monitor
When the VDD Monitor is selected as a reset source and 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 15.2). When VDD returns to a level above VRST, the CIP-51 will be released
from the reset state . Note that even though inter nal data memory contents are not altered by th e powe r-fa il
reset, it is impossible to determine if VDD droppe d below the leve l require d for dat a retention. If the PORSF
flag reads ‘1’, the data may no longer be valid. The VDD monitor is enabled and is selected as a reset
source after power-on resets; however its defined state (enabled/disabled) is not altered by a ny other reset
source. For example, if the VDD monitor is disabled by software, and a software reset is performed, the
VDD monitor will still be disabled after the reset. To protect the integrity of Flash contents, the VDD
monitor must be enabled to the higher setting (VDMLVL = '1') and selected as a reset source if so ft-
ware contains routines which erase or write Flash memory. If the VDD monitor is not enabled, any
erase or write performed on Flash memory will cause a Flash Error device reset.
The VDD monitor must be enabled before it is selected as a reset source. Selecting the VDD monitor
as a reset source before it is enabled and stabilized may cause a system reset. The procedure for re-
enabling the VDD monitor and configuring the VDD monitor as a reset source is shown below:
Step 1. Enable the VDD monitor (VDMEN bit in VDM0CN = ‘1’).
Step 2. Wait for the VDD monitor to stabilize (approximately 5 µs).
Note: This delay should be omitted if software contains routines which erase or
write Flash memory.
Step 3. Select the VDD monitor as a reset source (PORSF bit in RSTSRC = ‘1’).
See Figure 15.2 for VDD monitor timing; note that the reset delay is not incurred after a VDD monitor reset.
See Table 15.1 for complete electrical characteristics of the V DD monitor.
Note: Software should take care not to inadvertently disable the VDD Monitor as a reset source
when writing to RSTSRC to enable other reset sources or to trigger a software reset. All writes to
RSTSRC should explicitly set PORSF to '1' to ke ep the VDD Monitor enabled as a reset source.
C8051F410/1/2/3
130 Rev. 1.1
SFR Definition 15.1. VDM0CN: VDD Monitor Control
15.3. External Reset
The extern al 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 pi n genera tes a reset; a n externa l pullup a nd/or de coup ling of th e RST
pin may be necessary to avoid erroneous noise-induced resets. See Table 15.1 for complete RST pin
specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
15.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the s yst em clock . If the syst em
clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a
MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise,
this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables
it. The state of the RST pin is unaffected by this reset.
15.5. Comparator0 Reset
Comparator0 can be configured as a re set source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Com -
parator0 should b e enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter
on the output from gene rating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting
Bit7: VDMEN: VDD Monitor Enable.
This bit turns the V DD monitor circuit on/of f. The VDD Monitor cannot generate system re sets
until i t is al so sele cted as a reset source i n register RST SRC (SFR Definition 15.2). The V DD
Monitor can be allowed to stabilize before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it has stabilized may generate a system reset.
See Table 15.1 for the minimum VDD Monitor turn-on time.
0: VDD Monitor Disabled.
1: VDD Monitor Enabled (default).
Bit6: VDDSTAT: VDD Status.
This bit indicates the current power supply status (VDD Monitor output).
0: VDD is at or below the VDD Monitor Threshold.
1: VDD is above the VDD Monitor Threshold.
Bit5: VDMLVL: VDD Level Select.
0: VDD Monitor Threshold is set to VRST-LOW (default).
1: VDD Monitor Threshold is set to VRST-HIGH. This setting is recommended for any system
that includes code that writes to and/or erases Flash.
Bits4–0: Reserved. Read = Variable. Write = don’t care.
R/W R R/W R R R R R Reset Value
VDMEN VDDSTAT VDMLVL Reserved Reserved Reserved Reserved Reserved 1v000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xFF
C8051F410/1/2/3
Rev. 1.1 131
input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset
state. Af ter a Co mparator0 reset, th e C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the
reset source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset.
15.6. 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 “25.3. Watchdog Timer Mode” on
page 257; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a sys tem 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 th is reset.
15.7. Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
• A Flash write or erase is attempted a bove user code space . This occurs when PSWE is set to ‘1’ and a
MOVX write operation targets an address above the Lock Byte address.
• A Flash read is attempted above user code space. This occurs when a MOVC operation targets an
address above the Lock Byte address.
• A Program read is attemp ted above user code sp ac e. This occurs wh en user co de attempt s to branch
to an address above the Lock Byte address.
• A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section
“16.3. Security Options” on page 137).
• A Flash write or erase is attempted while the VDD Monitor is disabled.
The FERROR bit (RSTSRC.6) is set following a Flash erro r reset. The sta te of the RST pin is unaf fected by
this reset.
C8051F410/1/2/3
132 Rev. 1.1
15.8. smaRTClock (Real Time Clock) Reset
The smaRTClock can generate a system reset on two events: smaRTClock Oscillator Fail or smaRTClock
Alarm. The smaRTClock Oscillator Fail event occurs when the smaRTClock Missing Clock Detector is
enabled and the smaRTClock clock is below approximately 20 kHz. A smaRTClock alarm event occurs
when the smaRTClo ck Alarm is ena bled and th e smaRTClock timer value matches the ALARMn registers.
The smaRTClock can be configured as a reset source by writing a ‘1’ to the RTC0RE flag (RSTSRC.7).
The state of th e RST pin is unaffected by this reset.
15.9. Software Reset
Software may force a reset by writing a ‘1’ to the SWRSF bit (RSTSRC.4). The SWRSF bit will read ‘1’ fol-
lowing a software forced reset. The state of the RST pin is unaffected by this reset.
C8051F410/1/2/3
Rev. 1.1 133
SFR Definition 15.2. RSTSRC: Reset Source
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. [This applies to bits:
RTC0RE, C0RSEF, SWRSF, MCDRSF, PORSF].
Bit7: RTC0RE: smaRTClock (Real Time Clock) Reset Enable and Flag.
0: Read: Source of last reset was not a smaRTClock alarm or oscillator fail event.
Write: smaR TClock is not a reset source.
1: Read: Source of last reset was a smaRTClock alarm or oscillator fail event.
Write: smaR TClock is a reset source.
Bit6: FERROR: Flash Error Indicator.
0: Source of last reset was not a Flash read/write/erase error.
1: Source of last reset was a Flash read/write/erase error.
Bit5: C0RSEF: Comparator0 Reset Enable and Flag.
0: Read: Source of last reset was not Compa rator0.
Write: Comparator0 is not a reset source.
1: Read: Source of last reset was Compar ator0.
Write: Comparator0 is a reset source (active-low).
Bit4: SWRSF: Software Reset Force and Flag.
0: Read: Source of last reset was not a write to the SWRSF bit.
Write: No Effect.
1: Read: Source of last was a write to the SWRSF bit.
Write: Forces a system reset.
Bit3: WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
Bit2: MCDRSF: Missing Clock Detector Flag.
0: Read: Source of last reset was not a Missing Clock Detector tim eout.
Write: Missing Clock Detector disabled.
1: Read: Source of last reset was a Missing Clock Detector timeout.
Write: Missing Clock Detector enabled; triggers a reset if a missing clock condition is
detected.
Bit1: PORSF: Power-On Reset Force and Flag.
This bit is set anytime a power-on reset occurs. Writing this bit enables/disables the VDD
monitor as a rese t sour ce. Note: writing ‘1’ to this bit before the VDD monito r is enabled
and stabilized may cause a system reset. See register VDM0CN (SFR Definition 15.1)
0: Read: Last reset was not a power-on or VDD monitor reset.
Write: VDD monitor is not a reset source.
1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate.
Write: VDD monitor is a reset source.
Bit0: PINRSF: HW Pin Reset Flag.
0: Source of last reset was not RST pin.
1: Source of last reset was RST pin.
R/W R R/W R/W R R/W R/W R Reset Value
RTC0RE FERROR C0RSEF SWRSF WDTRSF MCDRSF PORSF PINRSF Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xEF
C8051F410/1/2/3
134 Rev. 1.1
Table 15.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified. Typical values are given at 25 ºC.
Parameter Conditions Min Typ Max Units
RST Output Low Voltage
VIO = 2.0 V:
IOL = 70 µA
IOL = 8.5 mA
VIO = 4.0 V:
IOL = 70 µA
IOL = 8.5 mA
—
—
—
—
—
—
—
—
50
800
40
400
mV
RST Input High Voltage 0.7 x VIO ——V
RST Input Low Voltage — — 0.3 x VIO V
RST Input Pullup Impedance VIO = 2.0 V
VIO = 5.0 V —
—150
70 —
—kΩ
VDD Monitor Threshold (VRST-LOW)1.91.952.0 V
VDD Monitor Threshold (VRST-HIGH)2.25 2.3 2.35 V
Missing Clock Detector Timeout Time from last system clock
rising edge to reset initiation 50 350 650 µs
Reset Time Delay Delay between release of any
reset source and code execu-
tion at location 0x0000 ——180µs
Minimum RST Low Time to Gener-
ate a System Reset 20 — — µs
VDD Monitor Supply Current —0.770µA
VDD Ramp Time VDD = 0 V to VDD = VRST V —— 1ms
C8051F410/1/2/3
Rev. 1.1 135
16. Flash Memory
On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The
Flash memory can be programmed in-system through the C2 interface or by software using the MOVX
write instruction. Once cleared to logic 0, a Flas h bit must be erased to set it back to lo gic 1. Flash bytes
would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are
automatica lly timed by hardwa re for proper executio n; data polling to deter mine th e end of the write/erase
operations is not required. Code execution is stalled during Flash write/erase operations. Refer to
Table 16.2 for complete Flash memory electrical characteristics.
16.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Laboratories or a third party vendor. This is the only means for programming a
non-initialized device. For details on the C2 commands to program Flash memory, see Section “26. C2
Interface” on page 265. For detailed guidelines on writing or erasing Flash from firmware, please see
Section “16. 4. Flash Write and Erase Guidelines” on page 139.
To ensure the integrity of the Flash contents, the on-chip VDD Monitor must be enabled to the
higher setting (VDMLVL = '1') in any system that includes code that writes and/or erases Flash
memory from software. Furthermore, there should be no delay between enabling the VDD Monitor
and enabling the VDD Monitor as a reset source. Any attempt to write or erase Flash memory while
the VDD Monitor disabled will cause a Flash Error device reset.
16.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be dis abled until th e next syste m reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be per-
formed. The FLKEY register is detailed in SFR Definition 16.2.
16.1.2. Flash Erase Procedure
The Flash memory can be programmed by software using the MOVX write instruction with the address and
data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX,
Flash write operations must be enabled by: (1) setting the PSWE Program Store Write Enable bit
(PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the Flash key
codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared by sof tware.
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed should be er ased before a new value is written.
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
Step 1. Disable interrupts (recommended).
Step 2. Write the first key code to FLKEY: 0xA5.
Step 3. Write the second key code to FLKEY: 0xF1.
Step 4. Set the PSEE bit (register PSCTL).
Step 5. Set the PSWE bit (register PSCTL).
Step 6. Using the MOVX instruction, write a data byte to any location within the 512-byte page to
be erased.
Step 7. Clear the PSWE and PSEE bits.
Step 8. Re-enable interrupts.
C8051F410/1/2/3
136 Rev. 1.1
16.1.3. Flash Write Procedure
Bytes in Flash memory can be written one byte at a time, or in groups of two. The FLBWE bit in register
PFE0CN (SFR Definition 13.1) controls whether a single byte or a block of two bytes is written to Flash
during a write operation. When FLBWE is cleared to ‘0’, the Flash will be written one byte at a time. When
FLBWE is set to ‘1’, the Flash will be written in two-byte blocks. Block writes are performed in the same
amount of time as single-byte writes, which can save time when storing large amounts of data to Flash
memory.
During a single-byte write to Flash, bytes are written individually, and a Flash write will be performed after
each MOVX write instruction. The recommended procedure for writing Flash in single bytes is:
Step 1. Disable interrupts.
Step 2. Clear the FLBWE bit (register PFE0CN) to select single-byte write mode.
Step 3. Write '0000' to FLSCL.3–0.
Step 4. Write the first key code to FLKEY: 0xA5.
Step 5. Write the second key code to FLKEY: 0xF1.
Step 6. Set the PSWE bit (register PSCTL).
Step 7. Clear the PSEE bit (register PSCTL).
S t ep 8. Using the MOVX instruction, write a single data byte to the desir ed location with in the 512-
byte sector.
Step 9. Clear the PSWE bit.
Step 10. Re-enable interrupts.
Steps 3–9 must be repeated for each byte to be written.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is writ-
ten with the MOVX write instruction. A Flash write block is two bytes long, from even addresses to odd
addresses. Writes must be performed sequentially (i.e. addresses ending in 0b and 1b must be written in
order). The Flash write will be performed fo llowing the MOVX write that targets th e a ddress en din g in 1b . If
a byte in the block does not need to be updated in Flash, it should be written to 0xFF. The re commended
procedure for writing Flash in bl ocks is:
Step 1. Disable interrupts.
Step 2. Set the FLBWE bit (register PFE0CN) to select block write mode.
Step 3. Write '0000' to FLSCL.3–0.
Step 4. Write the first key code to FLKEY: 0xA5.
Step 5. Write the second key code to FLKEY: 0xF1.
Step 6. Set the PSWE bit (register PSCTL).
Step 7. Clear the PSEE bit (register PSCTL).
Step 8. Using the MOVX instruction, write the first data byte to the even block location (ending in
0b).
Step 9. Clear the PSWE bit (r eg iste r PSCT L ).
Step 10. Write the first key code to FLKEY: 0xA5.
Step 11. Write the second key code to FLKEY: 0xF1.
Step 12. Set the PSWE bit (register PSCTL).
Step 13. Clear the PSEE bit (register PSCTL).
S t ep 14. Using the MOVX instruction, write the second dat a byte to the o dd block location (end ing
in 1b).
Step 15. Clear the PSWE bit (register PSCTL).
Step 16. Re-enable interrupts.
Steps 3-15 must be repeated for each block to be written.
C8051F410/1/2/3
Rev. 1.1 137
16.2. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and r ead us ing the M OVC instructi on. Note: MOVX read instru ctions always t a rget XRAM.
16.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before
software can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or alte red across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (re ads, writes, or er ases) by unprotected code or the C2 interface. The Flash security
mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to
0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the
page containing the Flash Security Lock Byte is unlocked when no other Flash pages are locked
(all bits of the Lock Byte are ‘1’) and locked when any other Flash pages are locked (any bit of the
Lock Byte is ‘0’). See the example below for an C8051F410.
Figure 16.1. Flash Program Memory Map
Security Lock Byte: 11111101b
1’s Complement: 00000010b
Flash pages locked: 3 (First two Flash pages + Lock Byte Page)
Addresses locked: 0x0000 to 0x03FF (first two Flash pages) and
0x7C00 to 0x7DFF (Lock Byte Page)
Access limit set
according to the Flash
security lock byte
0x0000
0x3FFF
Lock Byte
Reserved
0x3FFE
0x4000
Flash memory organized
in 512-byte pages
0x3E00
Unlocked Flash Pages
Locked when any
other Flash pages are
locked
0x0000
0x7DFF Lock B yte
Reserved
0x7DFE
0x7E00
0x7C00
Unlocked Flash Pages
C8051F410/1 C8051F412/3
C8051F410/1/2/3
138 Rev. 1.1
The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executin g on locked pages. Table 16.1 summarizes the Flash security
features of the 'F41x devices.
Table 16.1. Flash Security Summary
Action C2 Debug
Interface User Firmware executing from:
an unlocked page a locked page
Read, Write or Erase unlocked pages
(except page with Lock Byte) Permitted Permitted Permitted
Read, Write or Erase locked pages
(except page with Lock Byte) Not Permitted FEDR Permitted
Read or Write page containing Lock Byte
(if no pages are locked) Permitted Permitted Permitted
Read or Write page containing Lock Byte
(if any page is locked) Not Permitted FEDR Permitted
Read contents of Lock Byte
(if no pages are locked) Permitted Permitted Permitted
Read contents of Lock Byte
(if any page is locked) Not Permitted FEDR Permitted
Erase page containing Lock Byte
(if no pages are locked) Permitted FEDR FEDR
Erase page containing Lock Byte - Unlock all pages
(if any page is locked) Only C2DE FEDR FEDR
Lock additional pages
(change '1's to '0's in the Lock Byte) Not Permitted FEDR FEDR
Unlock individual pages
(change '0's to '1's in the Lock Byte) Not Permitted FEDR FEDR
Read, Write or Erase Reserved Area Not Permitted FEDR FEDR
C2DE - C2 Device Erase (Erases all Flash pages including the page containing the Lock Byte)
FEDR - Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after reset)
- All prohibited opera tions that ar e performed vi a the C2 in terface a re ignore d (do not cau se device r eset).
- Locking any Flash page also locks the page containing the Lock Byte.
- Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase.
- If user code writes to the Lock Byte, the Lock does not take effect until the next device reset.
C8051F410/1/2/3
Rev. 1.1 139
16.4. Flash Write and Erase Guidelines
Any system which contains routines which write or erase Flash memory from software involves some risk
that the write or erase routines will execute unintentionally if the CPU is operating outside its specified
operating range of VDD, system clock frequency, or temperature. This accidental execution of Flash modi-
fying code can result in alteration of Flash memory contents causing a system fa ilure that is only recov er-
able by re-Flashing the code in the device.
To help prevent the accidental modification of Flash by firmware, the VDD Monitor must be enabled and
enabled as a reset source on C8051F41x devices for the Flash to be successfully modified. If either the
VDD Monitor or the VDD Monitor reset source is not enabled, a Flash Error Device Reset will be
generated when the firmware attempts to modify the Flash.
The following guidelines are recommended for any system that contains routines which write or erase
Flash from code.
16.4.1. VDD Maintenance and the VDD Monitor
1. If the system power supply is subject to voltage or current "spikes," add sufficient transient
protection devices to the p ower supply to ensure that the supply volt ages listed in the Absolute
Maximum Ratings table are not exceeded.
2. Make cert ain that the minimum VDD rise time sp ecification of 1 ms is met. If the system cannot
meet this rise time specification, then add an external VDD brownout circuit to the /RST pin of
the device that holds the device in reset until VDD reaches VRST and re-a sserts /RST if VDD
drops below VRST.
3. Keep the on-chip VDD Monitor enabled and enable the VDD Monitor as a reset source as
early in code as possible. This should be the first set of instructions executed after the Reset
Vector. For 'C'-based systems, this will involve modifying the startup code added by the 'C'
compiler. See your compiler documentation for more details. Make certain that there are no
delays in software between enabling the VDD Monitor and enabling the VDD Monitor as a
reset source. Code examples showing this can be found in AN201, "Writing to Flash from
Firmware", available from the Silicon Laboratories web site.
Note: On C8051F41x devices, both the VDD Monitor and the VDD Monitor reset source must
be enabled to write or erase Flash without generating a Flash Error Device Reset.
4. As an adde d precaution, ex plicitly enable the VDD Monitor and ena ble the VDD Monitor as a
reset source inside the functions th at write and er ase Fla sh memory. The VDD Monitor enable
instructions should be placed just after the instruction to set PSWE to a '1', but before the
Flash write or erase operation instruction.
5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment
operators and explicitly DO NOT use the bit-wise operators (such as AND or OR). For exam-
ple, "RSTSRC = 0x02" is correct, but "RSTSRC |= 0x02" is incorrect.
6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a '1'. Areas
to check are initialization code which enables other reset sources, such as the Missing Clo ck
Detector or Comparator, for example, and instructions which force a Software Reset. A global
search on "RSTSRC" can quickly verify this.
C8051F410/1/2/3
140 Rev. 1.1
16.4.2. 16.4.2 PSWE Maintenance
7. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a '1'. There
should be exactly one routine in code that set s PSWE to a '1' to write Flash byte s and one rou -
tine in code that sets both PSWE and PSEE both to a '1' to erase Flash pages.
8. Minimize the number of variable accesses while PSWE is set to a '1'. Handle pointer address
updates and loop maintenance outside the "PSWE = 1; ... PSWE = 0;" area. Code examples
showing this can be found in AN201, "Writing to Flash from Firmware", available from the Sili-
con Laborator ies web site.
9. Disable in te rr up ts prior to se tting PSWE to a '1' and leave them disabled until after PSWE has
been reset to '0'. Any interrupts posted during the Flash write or erase operation will be ser-
viced in priority order after the Flash operation has been completed and interrupts have been
re-enabled by software.
10. Make certain that the Flash write and erase pointer variables are not located in XRAM. See
your compiler documentation for instructions regarding how to explicitly locate variables in dif-
ferent memory area s.
11. Add address bounds checking to the routines that write or erase Flash memory to ensure that
a routine called with an illegal address does not result in modification of the Flash.
16.4.3. System Clock
12. If operating from an external crystal, be advised that crystal performance is susceptible to
electrical interferen ce and is sensitive to layou t and to changes in tem perature. If the syste m is
operating in an electrically noisy environment, use the internal oscillator or use an external
CMOS clock.
13. If operating from the external oscillator, switch to the internal oscillator during Flash write or
erase operations. The external oscillator can continue to run, and the CPU can switch back to
the external osc i llat or after the Flas h op era tio n ha s c omp leted.
C8051F410/1/2/3
Rev. 1.1 141
SFR Definition 16.1. PSCTL: Program Store R/W Control
SFR Definition 16.2. FLKEY: Flash Lock and Key
Bits7–2: UNUSED: Read = 000000b, Write = don’t care.
Bit1: PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memor y
to be erased. If this bit is logic 1 and Flash writes ar e enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the loca-
tion addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory era sure disabled.
1: Flash program memory erasure enabled.
Bit0: PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash progra m mem o ry disab l e d.
1: Writes to Flash program memory enable d ; the MOVX write instruction targets Flash
memory.
RRRRRRR/WR/WReset Value
- - - - - - PSEE PSWE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8F
Bits7–0: FLKEY: Flash Lock and Key Register
Write:
This register provides a lock and key function for Flash erasures and writes. Flash writes
and erases are enabled by writing 0xA5 followed by 0xF1 to the FLKEY register. Flash
writes and erases ar e auto matically disabled af ter th e next write or erase is co mplete. If any
writes to FLKEY are performed incorrectly, or if a Flash write or erase operation is attempted
while these operations ar e disabled, the Fl ash will be permanen tly locked from wr ites or era-
sures until the next device reset. If an application never writes to Flash, it can intentionally
lock the Flash by writing a non-0xA5 value to FLKEY fro m software.
Read:
When read, bits 1 -0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash wr ites/erases disabled until the next reset.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB7
C8051F410/1/2/3
142 Rev. 1.1
16.5. Flash Read Timing
On reset, the C8051F41x Flash read timing is configured for operation with system clocks up to 25 MHz. If
the system clock will not be increased above 25 MHz, then the Flash timing registers may be left at their
reset value.
For every Flash read or fetch , the system provide s an internal Flash read strobe to the Flash memory. The
Flash read strobe lasts for one or two system clock cycles, based on FLRT (FLSCL.4). If the system
clock is greater than 25 MHz, the FLRT bit must be set to logic 1, otherwise data read or fetched from
Flash may not represent the actual contents of Flash.
When the Flash read strobe is asserted, Flash memory is active. When it is de-asserted, Flash memory is
in a low power state. The Flash r ead strobe does not need to be asserted for longer than 80 ns in order for
Flash reads and fetches to be reliable. For system clocks greater than 12.5 MHz (but less than 25 MHz),
the Flash read strobe width is limited by the system clock period. For system clocks less than 12.5 MHz,
the Flash r ead strobe is limited by a programmable one shot with a default period of 80 ns (1/12.5 MHz).
This is a power saving feature that is very beneficial for very slow system clocks (e.g. 32.768 kHz where
the system clock period is greater than 30,000 ns).
For additional power savings, the one shot can be programmed to values less than 80 ns. The one shot
can be trimmed according the equation in the ONESHOT register description in Figure 16.4. The one shot
period must not be programmed less than the minimum read cycle time specified in Table 16.2.
The recommended procedure for updating FLRT or the ONESHOT period is:
Step 1. Select SYSCLK to 25 MHz or less.
Step 2. Disable the prefetch engine (PFEN = ‘0’ in PFE0CN register).
Step 3. Clear FLRT to ‘0’ (FLSCL register).
Step 4. Set the ONESHOT period bits.
Step 5. Set FLRT to ‘1’ if SYSCLK > 25 MHz.
Step 6. Enable the prefetch engine (PFEN = ‘1’ in PFE0CN register).
SFR Definition 16.3. FLSCL: Flash Scale
Bits7–5: RESERVED. Read = 000b. Must Write 000b.
Bit 4: FLRT: Flash Read Time Control.
This bit should be pr ogrammed to the smalle st allowed value, according to the system clock
speed.
0: SYSCLK < 25 MHz (Flash read strobe is one system clock).
1: SYSCLK > 25 MHz (Flash read strobe is two system clocks).
Bits3–0: RESERVED. Must Write 0000b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Reserved Reserved Reserved FLRT Reserved Reserved Reserved Reserved 00000011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB6
C8051F410/1/2/3
Rev. 1.1 143
SFR Definition 16.4. ONESHOT: Flash Oneshot Period
Table 16.2. Flash Electrical Characteristics
VDD = 2.0 to 2.7 5 V; –40 to +85 ºC unless otherwise specified. Typical values are given at 25 ºC.
Parameter Conditions Min Typ Max Units
Flash Size C8051F410/1
C8051F412/3 32768*
16384 —— bytes
Endurance VDD is 2.2 V or greater 20 k 90 k — Erase/Write
Erase Cycle Time FLSCL.3–0 written to '0000' 16 20 24 ms
Write Cycle Time FLSCL.3–0 written to '0000' 38 46 57 µs
Read Cycle Time 40 — — ns
VDD Write/Erase Operations 2.25 — — V
*Note: 512 bytes at addresses 0x7E00 to 0x7FFF are reserved.
Bits7–4: UNUSED. Read = 0000b. Write = don’t care.
Bits3–0: PERIOD: Ones ho t Per iod Con tr ol Bits.
These bits limit the internal Flash read strobe width as follows. When the Flash read strobe
is de-asserted, the Flash memory enters a low-power state for the remainder of the system
clock cycle. These bit s have no ef fect when the system clocks is greater than 12.5 MHz and
FLRT = 0.
R R R R R/W R/W R/W R/W Reset Value
---- PERIOD 00001111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAF
FLASHRDMAX 5ns PERIOD 5ns×()+=
C8051F410/1/2/3
144 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 145
17. External RAM
The C8051F41x devices include 2048 bytes of RAM mapped into th e external data memory space. All of
these address locations may be accessed using the external move instruction (MOVX) and the data
pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit
address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Mem-
ory Interface Control Register (EMI0CN as shown in SFR Definition 17.1). Note: the MOVX instruction is
also used fo r writ es to th e F lash m e mo r y. See Section “16. Flash Memory” on page 135 for details. The
MOVX instruction accesses XRAM by default.
For a 16-bit MOVX operation (@DPTR), the upper 5-bits of the 16-bit external data memory address word
are "don't cares.” As a result, the RAM is mapped modulo style over the entire 64 k external data memory
address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses 0x0800,
0x1000, 0x1800, 0x2000, e tc. This is a u s eful featu re when per form ing a li ne ar memory fill, as the add ress
pointer doesn't have to be reset when reaching the RAM block boundary.
SFR Definition 17.1. EMI0CN: External Memory Interface Control
Bits 7–3: UNUSED. Read = 00000b. Write = don’t care.
Bits 2–0: PGSEL: XRAM Page Select.
The EMI0CN register provides the high byte of the 16-bit external data memory address
when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. Since
the upper (unused) bits of the register are always zero, the PGSEL determines which page
of XRAM is accessed.
For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - - PGSEL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAA
C8051F410/1/2/3
146 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 147
18. Por t Input/Output
Digital and analog reso urces a re available thr ough up to 24 I/O p ins. Port pins are o rganized as three b yte-
wide Ports. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog input/output;
Port pins P0.0 - P2.7 can be assigned to one of the internal digital resources as shown in Figure 18.3. 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.
Note that the state of a Port I/O pin can always be read in the corresponding Port latch, regardless of the
Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the perip heral priority
order of the Priority Decoder (Figure 18.3 and Figure 18.4). The registers XBR0 and XBR1, defin ed in SFR
Definition 18.1 and SFR Definition 18.2, are used to select internal digital functions.
Port I/Os on P0 are 5 V tolerant over the operating range of VIO. Port I/Os on P1 and P2 should not be
driven above VIO or they will sink current. Figure 18.2 shows the Port cell circuit. The Port I/O cells are
configured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n =
0,1,2). Complete Electrical Specifications for Port I/O are given in Table 18.1 on page 163.
Figure 18.1. Port I/O Functional Block Diagram
XBR0, XBR1,
P nSK IP Regi s ter s
Digital
Crossbar
Priority
Decoder
2
P0
I/O
Cells
P0.0
P0.7
8
P0MASK, P0MATCH
P1MASK, P1MATCH
Registers
UART
(Internal Digital Signals)
Highest
Priority
Lowest
Priority
SYSCLK
2
SMBus
T0, T1 2
7
PCA
4
CP0
CP1
Outputs
SPI 4
P1
I/O
Cells
P1.0
P1.7
8
(Port Latches)
P0 (P0.0-P0.7)
(P1.0-P1.7)
8
8
P1
P2
I/O
Cell
P2 (P2.0-P2.7)
8
8P2.0
P2.7
PnMD OUT,
PnM DIN R egisters
P2.3–2.6 available on
C8051F410/2
C8051F410/1/2/3
148 Rev. 1.1
Figure 18.2. Port I/O Cell Block Diagram
GND
/PORT-OUTENABLE
PORT-OUTPUT
PUSH-PULL VIO VIO
/WEAK-PULLUP
(WEAK)
PORT
PAD
ANALOG INPUT
Analog Select
PORT-INPUT
C8051F410/1/2/3
Rev. 1.1 149
18.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 18.3) 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 will be assigned to pins P0.4 and P0.5). If a Port pin is assigned, the
Crossbar skips that pin when assign ing the next selected resource . Additionally, the Crossbar will skip Port
pins whose associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip
Port pins that are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to P1.0 and/or P1.1 for the external
oscillator, P1.2 for VREF, P0.6 for the external CNVSTR signal, P0.0 for IDA0, P0.1 for IDA1, 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 18.3 shows th e Crossb ar Decode r priority wit h no Port pins
skipped (P0SKIP, P1SKIP, P2SKIP = 0x00); Figure 18.4 shows the Crossbar Decoder priority with the
XTAL1 (P1.0) and XTAL2 (P1.1) pins skipped (P1SKIP = 0x03).
Figure 18.3. Crossbar Priority Decoder with No Pins Skipped
i0 i1 cnvstr x1 x2 vref
012345670123456701234567
(* 4-Wi re SPI On l y )
CP0
CP0A
CP1
CP1A
/SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
T0
T1
000000000000000000000000
SDA
P0SKIP[0:7]
SCL
RX0
SF Signa ls
PIN I/O
TX0
NSS*
SCK
MISO
MOSI
P2
P2SKIP[0:7]
P0 P1
P1SKIP[0:7]
C8051F410/1/2/3
150 Rev. 1.1
Figure 18.4. Crossbar Priority Decoder with Crystal Pins Skipped
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note
that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and
SCL); when the UAR T is selected, the Crossbar assign s both pins associated with the UART (TX and RX).
UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART
RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously starting at P0.0 after prioritized
functions and skipped pins are assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, depending on the state of the
NSSMD1-NSSMD0 bits in register SPI0CN. Accordin g to the SPI mode, the NSS signal may or may not be
routed to a Port pin.
i0 i1 cnvstr x1 x2 vref
012345670123456701234567
(*4 -Wire S PI On ly)
CP0
CP0A
CP1
CP1A
/SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
T0
T1
000000001100000000000000
SCL
P0
RX0
SF Signals
S pec ial Func t ion Signals are not as s igned by the c ros s bar. W hen t hes e s ignals are enabled,
the Cros s B ar m us t be m anually c onfigured to s k ip their c orresponding port pins .
P ort pin potentially as s ignable to peripheral
NSS*
P2
P 0S KIP [0:7] P 1S KIP [0:7] = 0x03 P 2S KI P [0:7]
TX0
P1
SDA
SF Signals
SCK
MISO
MOSI
PIN I/O
C8051F410/1/2/3
Rev. 1.1 151
18.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode
register (PnMDIN). If the pin is in analog mode, a '1' must also be written to the
corresponding Port Latch.
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output
Mode register (PnM DO UT ) .
Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
Step 4. Assign Port pins to desired peripherals using the XBRn registers.
Step 5. Enable the Crossbar (XBARE = ‘1’).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pullup, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digit a l input s may still be used by anal og perip herals; ho weve r, this
practice is not recommended.
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates
a digital input, and a ‘0’ indicates an analog input. All port pins in analog mode must have a '1' set in the
corresponding Port Latch register. All pins default to digital inputs on reset. See SFR Definition 18.4 for the
PnMDIN register details.
Important Note: Port 0 pins are 5 V tolerant across the operating range of VIO. Figure 18.5 shows the
input current range of P0 p ins when overdriven above VIO (when VIO is 3.3 V nominal). There are two over-
drive modes for Port 0: Normal and High-Impedance. When the corresponding bit in P0ODEN is logic 0,
Normal Overdrive Mode is selected and the port pin requires 150 µA peak overdrive current when its volt-
age reaches approximately VIO + 0.7 V. When the corresponding bit in P0ODEN is logic 1, High-Imped-
ance Overdrive Mode is selected and the port pin does not require any additional overdrive current. Pins
configured to High-Impedance Overdrive Mode consume slightly more power from VIO than pins config-
ured to Normal Overdrive Mode. Note that Port 1 and Port 2 pins cannot be overdriven above VIO and
have the same behavior as P0 in Normal Mode.
C8051F410/1/2/3
152 Rev. 1.1
Figure 18.5. Port 0 Input Overdrive Current Range
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD-
OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pullup is enabled for all Port I/O con-
figured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is
turned of f on an output that is driving a ‘0’ and for pins configured for analog input mode to avoid unneces-
sary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table.
The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers
are disabled while the Crossbar is disabled.
+
-Vtest
IVtest
VDD
IVtest (µA)
Vtest (V)
0
-10
-150
VIO VIO+0.7
I/O
Cell
P0.x
pin
VIO
IVtest (µA)
Vtest (V )
0
10
VIO-0.2 VIO+0.2
-10
Normal Mode
P0ODEN.x = 0
High-Imped ance Mode
P0ODEN.x = 1
C8051F410/1/2/3
Rev. 1.1 153
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0
Bit7: CP1AE: Comparator1 Asynchronous Output Enable
0: Asynchronou s C P1 un available at Port pin.
1: Asynchronous CP1 routed to Port pin.
Bit6: CP1E: Comparator1 Output Enable
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
Bit5: CP0AE: Comparator0 Asynchronous Output Enable
0: Asynchronou s C P0 un available at Port pin.
1: Asynchronous CP0 routed to Port pin.
Bit4: CP0E: Comparator0 Output Enable
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
Bit3: SYSCKE: /SYSCLK Output Enable
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
Bit2: SMB0E: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
Bit1: SPI0E: SPI I/O Enable
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins. Note that the SPI can be assigned either 3 or 4 GPIO pins.
Bit0: URT0E: UART I/O Output Enable
0: UART I/O unavailable at Port pin.
1: UART TX0, RX0 routed to Port pins P0.4 and P0.5.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CP1AE CP1E CP0AE CP0E SYSCKE SMB0E SPI0E URT0E 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE1
C8051F410/1/2/3
154 Rev. 1.1
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1
18.3. 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. Ports P0-P2 are accessed through corresponding special function registers (SFRs)
that are both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is
latched to maint ain the outp ut dat a value at each pin. When reading, the logic levels of the Port's input pins
are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the
Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the
execution of the read-modify-write instructions that target a Port Latch register as the destination. The
read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL,
INC, DEC, DJNZ and MOV, CLR or SETB, when the destination is an individual bit in a Port SFR. For
these instructions, the value of the latch register (not the pin) is read, modified, and written back to the
SFR.
In addition to performing general purpose I/O, P0 and P1 can generate a port match event if the logic lev-
els of the Port’s input pins match a software controlled value. A port match event is generated if
(P0 & P0MASK) does not equal (P0MATCH & P0MASK) or if (P1 & P1MASK) does not equal
Bit7: WEAKPUD: Port I/O Weak Pullup Disable.
0: Weak Pullu ps enabled (except for Ports whose I/O are configured as analog input).
1: Weak Pullups disabled.
Bit6: XBARE: Crossbar Enable.
0: Crossbar disabled.
1: Crossbar enabled.
Bit5: T1E: T1 Enable
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit4: T0E: T0 Enable
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit3: ECIE: PCA0 External Counter Input Enable
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Bits2–0: PCA0ME: PCA Module I/O Enable Bits.
000: All PCA I/O unavailable at Port pins.
001: CEX0 routed to Port pin.
010: CEX0, CEX1 routed to Port pins.
011: CEX0, CEX1, CEX2 routed to Port pins.
100: CEX0, CEX1, CEX2, CEX3 routed to Port pins.
101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins.
110: CEX0, CEX1, CEX2, CEX3, CEX4, CEX5 routed to Port pins.
111: Reserved.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
WEAKPUD XBARE T1E T0E ECIE PCA0ME 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE2
C8051F410/1/2/3
Rev. 1.1 155
(P1MATCH & P1MASK). This allows Software to be notified if a certain change or pattern occurs on P0 or
P1 input pins regardless of the XBRn settings. A port match event can cause an interr upt if EM AT (EIE2.1)
is set to '1' or cause the internal oscillator to awaken from SUSPEND mode. See Section “19.1.1. Internal
Oscillator Suspend Mode” on page 166 for more information.
SFR Definition 18.3. P0: Port0
SFR Definition 18.4. P0MDIN: Port0 Input Mode
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0).
Read - Always reads ‘0’ 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.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0x80
Bits7–0: Analog Input Configuration Bits for P0.7–P 0. 0 (r espe ctively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P0 .n pin is configured as an an alog input. In order for the P0 .n pin to be
in analog input mode, there MUST be a '1' in the Port Latch register cor responding to
that pin.
1: Corresponding P0.n pin is not configured as an analog inpu t.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF1
C8051F410/1/2/3
156 Rev. 1.1
SFR Definition 18.5. P0MDOUT: Port0 Output Mode
SFR Definition 18.6. P0SKIP: Port0 Skip
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, ea ch are open-drain regardless
of the value of P0MDOUT).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA4
Bits7–0: P0SKIP[7:0]: Port0 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.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD4
C8051F410/1/2/3
Rev. 1.1 157
SFR Definition 18.7. P0MAT: Port0 Match
SFR Definition 18.8. P0MASK: Port0 Mask
SFR Definition 18.9. P0ODEN: Port0 Overdrive Mode
Bits7–0: P0MAT[7:0]: Port0 Match Value.
These bits control the value that unmasked P0 Port pins are compa red against. A Port
Match event is generated if (P0 & P0MASK) does not equal (P0MAT & P0MASK).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD7
Bits7–0: P0MASK[7:0]: Port0 Mask Value.
These bits select which Port pins will be compared to the value stored in P0MAT.
0: Corresponding P0.n pin is ignored and cannot cause a Port Match event.
1: Corresponding P0.n pin is compared to the corresponding bit in P0MAT.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC7
Bits7–0: High Impedance Overdrive Mode Enable Bits for P0.7–P0.0 (respectively).
Port pins configured to High-Impedance Overdrive Mode do not require additional overdrive
current, alth oug h selectin g this mo de results in a slight increase in supply cu rr ent. Por t pin s
configured to Normal Overdrive Mode require approximately 150 µA of input overdrive cu r-
rent when the voltage at th e pin reaches VIO+0.7 V.
0: Corresponding P0.n pin is configured to Normal Overdrive Mode.
1: Corresponding P0.n pin is configured to High-Impedance Overdrive Mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB0
C8051F410/1/2/3
158 Rev. 1.1
SFR Definition 18.10. P1: Port1
SFR Definition 18.11. P1MDIN: Port1 Input Mode
Bits7–0: P1.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P1MDIN. Directly reads Port
pin when configured as digital input.
0: P1.n pin is logic low.
1: P1.n pin is logic high.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0x90
Bits7–0: Analog Input Configuration Bits for P1.7–P 1. 0 (r espe ctively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P1 .n pin is configured as an an alog input. In order for the P1 .n pin to be
in analog input mode, there MUST be a '1' in the Port Latch register cor responding to
that pin.
1: Corresponding P1.n pin is not configured as an analog inpu t.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF2
C8051F410/1/2/3
Rev. 1.1 159
SFR Definition 18.12. P1MDOUT: Port1 Output Mode
SFR Definition 18.13. P1SKIP: Port1 Skip
Bits7–0: Output Configuration Bits for P1.7–P1.0 (respectively): ignored if corresponding bit in regis-
ter P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push-pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA5
Bits7–0: P1SKIP[7:0]: Port1 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 P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD5
C8051F410/1/2/3
160 Rev. 1.1
SFR Definition 18.14. P1MAT: Port1 Match
SFR Definition 18.15. P1MASK: Port1 Ma sk
Bits7–0: P1MAT[7:0]: Port1 Match Value.
These bits control the value that unmasked P0 Port pins are compa red against. A Port
Match event is generated if (P1 & P1MASK) does not equal (P1MAT & P1MASK).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCF
Bits7–0: P1MASK[7:0]: Port1 Mask Value.
These bits select which Port pins will be compared to the value stored in P1MAT.
0: Corresponding P1.n pin is ignored and cannot cause a Port Match event.
1: Corresponding P1.n pin is compared to the corresponding bit in P1MAT.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xBF
C8051F410/1/2/3
Rev. 1.1 161
SFR Definition 18.16. P2: Port2
SFR Definition 18.17. P2MDIN: Port2 Input Mode
Bits7–0: P2.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P2MDIN. Directly reads Port
pin when configured as digital input.
0: P2.n pin is logic low.
1: P2.n pin is logic high.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xA0
Bits7–0: Analog Input Configuration Bits for P2.7–P 2. 0 (r espe ctively).
Port pins configured as analog inputs have their weak pullup, digital driver, and digital
receiver disabled.
0: Corresponding P2 .n pin is configured as an an alog input. In order for the P2 .n pin to be
in analog input mode, there MUST be a '1' in the Port Latch register cor responding to
that pin.
1: Corresponding P2.n pin is not configured as an analog inpu t.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF3
C8051F410/1/2/3
162 Rev. 1.1
SFR Definition 18.18. P2MDOUT: Port2 Output Mode
SFR Definition 18.19. P2SKIP: Port2 Skip
Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in regis-
ter P2MDIN is logic 0.
0: Corresponding P2.n Output is open-drain.
1: Corresponding P2.n Output is push-pull.
RRRRRRRR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA6
Bits7–0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits .
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as 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 P2.n pin is not skipped by the Crossbar.
1: Corresponding P2.n pin is skipped by the Crossbar.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD6
C8051F410/1/2/3
Rev. 1.1 163
Table 18.1. Port I/O DC Electrical Characteristics
VIO = 2.0 to 5.25 V, –40 to +85 °C unless otherwise specified. Typical values are given at 25 ºC.
Parameters Conditions Min Typ Max Units
Output High Voltage IOH = –3 mA, Port I/O push-pull
IOH = –70 µA, Port I/O push-pull
VIO – 0.5
VIO – 50 mV —
——
—V
Output Low Voltage
VIO = 2.0 V:
IOL = 70 µA
IOL = 8.5 mA
VIO = 4.0 V:
IOL = 70 µA
IOL = 8.5 mA
—
—
—
—
—
—
—
—
50
800
40
400
mV
Input High Voltage VIO x 0.7 ——V
Input Low Voltage — — VIO x 0.3 V
Input Leakage Current Weak Pullup Off —< 0.1 ±1 µA
Weak Pullup Impedance —120 — kΩ
C8051F410/1/2/3
164 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 165
19. Oscillators
C8051F41x devices include a programmable internal oscillator, an external oscillator drive circuit, and a
Clock Multiplier. The internal oscillator can be enabled/disabled and calibrated using the OSCICN and
OSCICL registers, as shown in Figure 19.1. The system clock (SYSCLK) can be derived from the internal
oscillator , external oscillator circuit, or smaRTClock oscillator . The clock multiplier can produce three possi-
ble base outputs which can be scaled by a programmable factor of 1, 2/3, 2/4 (or 1/2), 2/5, 2/ 6 (or 1 /3), o r
2/7: Int ernal Oscillator x 2, External Oscillator x 2, or External Oscillator x 4. Oscillator electrical specifica-
tions are given in Table 19.1 on page 175.
Figure 19.1. Oscillator Diagram
19.1. Programmable Internal Oscillator
All C8051F41x device s inc lud e a pr og ra m m ab le internal oscillator that defaults as the system clock after a
system reset. The internal oscillator period can be programmed via the OSCICL register, shown in SFR
Definition 19.2. On C8051F41x devices, OSCICL is factory calibrated to obtai n a 24.5 MHz frequency.
Electrical specifications for the precision internal oscillator are given in Table 19.1 on page 175. Note that
the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, 8, 16, 32, 64,
or 128 as defined by the IFCN bits in register OSCICN. The divide value defaults to 128 following a reset.
C lo ck Multiplie r
OSC EXOSC
Input
Circuit
XTLVLD
XTAL1
XTAL2
Option 2
VDD
XTAL2
Option 1
10MΩ
Option 3
XTAL2
Option 4
XTAL2
OSCXCN
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
XFCN2
XFCN1
XFCN0
CLKMUL
MULEN
MULINIT
MULRDY
MULSEL1
MULSEL0
Programmable
Inte r n al Clock
Generator
EN
OSCICL OSCICN
IOSCEN
IFRDY
SUSPEND
IFCN1
IFCN0
IOSC
EXOSC / 2 x4
EXOSC
IOSC/2
SYSCLK
CLKSEL
CLKSL1
CLKSL0
n
n
smaR TC lock
Oscillator
IFCN2
IOSC
MULDIV2
MULDIV1
MULDIV0
C8051F410/1/2/3
166 Rev. 1.1
19.1.1. Internal Oscillator Suspend Mode
When software writes a logic 1 to SUSPEND (OSCICN.5), the internal oscillator is suspended. If the sys-
tem clock is derived from the internal oscillator, the input clock to the peripheral or CIP-51 will be stopped
until one of the following events occur:
• Port 0 Matc h Even t.
• Port 1 Matc h Even t.
•Comparator 0 enabled and output is logic 0.
•Comparator 1 enabled and output is logic 0.
• smaRTClock Oscillator Fail Event.
• smaRTClo ck Alarm Event.
When one of the internal oscillator awakening events occur, the internal oscillator, CIP-51, and affected
peripherals resume normal operation, regardless of whether the event also causes an interrupt. The CPU
resumes execution at the instruction following the write to SUSPEND.
C8051F410/1/2/3
Rev. 1.1 167
SFR Definition 19.1. OSCICN: Internal Oscillator Control
SFR Definition 19.2. OSCICL: Internal Oscillator Calibration
Bit7: IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit6: IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator is not running at programmed frequency.
1: Internal Oscillator is running at programmed frequency.
Bit5: SUSPEND: Internal Oscillator Suspend Enable Bit.
Setting this bit to logic 1 places the internal oscillator in SUSPEND mode. The internal oscil-
lator resumes operation when one of the SUSPEND mode awakening events occur.
Bits4–3: UNUSED. Read = 00b, Write = don't care.
Bits2–0: IFCN2–0: Internal Oscillator Frequency Co ntrol Bits.
000: SYSCLK derived from Internal Oscillator divided by 128 (default).
001: SYSCLK derived from Internal Oscillator divided by 64.
010: SYSCLK derived from Internal Oscillator divided by 32.
011: SYSCLK derived from Internal Oscillator divided by 16.
100: SYSCLK derived from Internal Oscillator divided by 8.
101: SYSCLK derived from Internal Oscillator divided by 4.
110: SYSCLK derived from Internal Oscillator divided by 2.
111: SYSCLK derived from Internal Oscillator divided by 1.
R/W R R/W R R R/W R/W R/W Reset Value
IOSCEN IFRDY SUSPEND - - IFCN2 IFCN1 IFCN0 11000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB2
Bit7: UNUSED. Read = 0. Write = don’t care.
Bits 6–0: OSCICL: Internal Oscillator Calibration Register.
This register determines the internal oscillator period. On C8051F41x devices, the re set
value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz.
R R/W R/W R/W R/W R/W R/W R/W Reset Value
-OSCICLVaries
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB3
C8051F410/1/2/3
168 Rev. 1.1
19.2. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crys-
tal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 19.1. A
10 MΩ resistor also must be wired across the XTAL1 and XTAL2 pins for the crystal/resonator configura-
tion. In RC, capacitor, or CMOS c loc k configuration, the clock source should be wired to the XTAL2 pin as
shown in Option 2, 3, or 4 of Figure 19.1. The type of exter nal oscillat or m ust be select ed in t he O SCX CN
register, and the frequency control bits (XFCN) must be selected appropriately (see SFR
Definition 19.3. OSCXCN: External Oscillator Control).
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P1.0 and P1.1 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is
enabled in capacitor, RC, or CMOS clock mode, Port pin P1.1 is used as XTAL2. The Port I/O Crossbar
should be configur ed to skip the Port pins used by the oscillator circuit; see Section “18.1. Priority Cross-
bar Decoder” on page 149 for Crossbar configuration. Additionally, when using th e external osc i llato r cir -
cuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog
inputs (with ‘1's in the corresponding Port Latch). In CMOS clock mode, the associated pin should be con-
figured as a digital input. See Section “18.2. Port I/O Initialization” on page 151 for details on Port
input mode selection.
The frequency of the external oscillator can be measured with respect to the smaRTClock Oscillator using
Timer 2 or Timer 3. Section “24.2.3. External/smaRTClock Capture Mode” on page 241 shows how this
can be accomplished.
19.2.1. Clocking Timers Directly Through the External Oscillator
The external oscillator source divided by eight is a clock option for the timers (Section “24. Timers” on
page 231) and the Programmable Counter Array (PCA) (Section “25. Programmable Counter Array
(PCA0)” on page 249). When the external oscillator is used to clock these peripherals, but is not used as
the system clock, the external oscillator frequency must be less than or equal to the system clock fre-
quency. In this configuration, the clock supplied to the peripheral (external oscillator / 8) is synchronized
with the system clock; the jitter associated with this synchronization is limited to ±0.5 system clock cycles.
19.2.2. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MC U, th e cir cuit sh ould be
configured as shown in Figure 19.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the t able in SFR Definition 19.3. For example, a 12 MHz crys-
tal requires an XFCN setting of 111b.
C8051F410/1/2/3
Rev. 1.1 169
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpred ictable behavior. The rec -
ommended procedure is:
Step 1. Force the XTAL1 and XTAL2 pins low by writing 0's to the port latch.
Step 2. Configure XTAL1 and XTAL2 as analog inputs.
Step 3. Release the crystal pins by writing ‘1's to the port latch.
Step 4. Enable the external oscillator.
Step 5. Wait at least 1 ms.
Step 6. Poll for XTLVLD => '1'.
Step 7. Switch the system clock to the external oscillator.
Note: Tuning-fork c rys tals may require ad dit ion al se ttlin g time be fo re XTLVLD retu rn s a valid result .
The capacitors shown in the external crystal configuration provide the load capacitance required by the
crystal for correct oscillation. These capacitors are "in series" as seen by the crystal and "in parallel" with
the stray capacitance of the XTAL1 and XTAL2 pins.
Note: The load capacitance depends upon the crystal and the manufacturer. Please refer to the crystal
data sheet when completing these calculations.
For example, a tuning-fork cry stal of 32.768 kHz with a recommended load capacitance of 12.5 pF should
use the configuration shown in Figure 19.1, Option 1. The tot al val ue of the cap acitors and the stray cap ac-
itance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors
yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 19.2.
Figure 19.2. 32.768 kHz External Crystal Example
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
22 pF
22 pF
32.768 kHz 10 M
XTAL1
XTAL2
Ω
C8051F410/1/2/3
170 Rev. 1.1
19.2.3. 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 19.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 kΩ and C = 50 pF:
f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 x 50 ] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 19.3, the required XFCN setting is 010b. Programming XFCN to a
higher setting in RC mode will improve frequency accuracy at a slightly increased external oscillator supply
current.
19.2.4. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 19.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the fre-
quency of oscillation and calculate the capacitance to be used from the equations below. Assume
VDD = 2.0 V and f = 75 kHz:
f = KF / (C x VDD)
0.075 MHz = KF / (C x 2.0)
Since the frequency of roughly 75 kHz is desired, select the K Fact or from the table in SFR Definition 19.3
as KF = 7.7:
0.075 MHz = 7.7 / (C x 2.0)
C x 2.0 = 7.7 / 0.075 MHz
C = 102.6 / 2.0 pF = 51.3 pF
Therefore, the XFCN value to use in this example is 010b.
C8051F410/1/2/3
Rev. 1.1 171
SFR Definition 19.3. OSCXCN: External Oscillator Control
Bit7: XTLVLD: Crystal Oscillator Valid Flag. (Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clo ck Mode .
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3: RESERVED. Read = 0b; Must write 0b.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000-111: See table below:
Crystal Mode (Circuit from Figure 19.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal or resonator frequency.
RC Mode (Circuit from Figure 19.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
f = 1.23(103) / (R x C), where
f = frequency of clock in MHz
C = capacitor value in pF
R = Pullup resistor value in kΩ
C Mode (Circuit from Figure 19.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x VDD), where
f = frequency of clock in MHz
C = capacitor value the XTAL2 pin in pF
VDD = Power Supply on MCU in volts
R R/W R/W R/W R/W R/W R/W R/W Reset Value
XTLVLD XOSCMD2XOSCMD1 XOSCMD0 Reserved XFCN2 XFCN1 XFCN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB1
XFCN Crystal (XOSCMD = 11x) RC (XOSCMD = 10x) C (XOSCMD = 10x)
000 f ≤ 20 kHz f ≤ 25 kHz K Factor = 0.87
001 20 kHz < f ≤ 58 kHz 25 kHz < f ≤ 50 kHz K Factor = 2.6
010 58 kHz < f ≤ 155 kHz 50 kHz < f ≤ 100 kHz K Factor = 7.7
011 155 kHz < f ≤ 415 kHz 100 kHz < f ≤ 200 kHz K Factor = 22
100 415 kHz < f ≤ 1.1 MHz 200 kHz < f ≤ 400 kHz K Factor = 65
101 1.1 MHz < f ≤ 3.1 MHz 40 0 kHz < f ≤ 800 kHz K Factor = 180
110 3.1 MHz < f ≤ 8.2 MHz 8 00 kHz < f ≤ 1.6 MHz K Factor = 664
111 8.2 MHz < f ≤ 25 MHz 1.6 MHz < f ≤ 3.2 MHz K Factor = 1590
C8051F410/1/2/3
172 Rev. 1.1
19.3. Clock Multiplier
The Clock Multip lier genera tes an outp ut clock wh ich is 4 times th e input clock fr equency sc aled by a p ro-
grammable factor of 1, 2/3, 2/4 (or 1/2), 2/5, 2/6 (or 1/3), or 2/7. The Clock Multiplier’s input can be
selected from the external oscillator, or the internal or exter nal oscil lators di vided by 2. This produces three
possible base outputs which can be scaled by a programmable factor: Internal Oscillator x 2, External
Oscillator x 2, or External Oscillator x 4. See Se ct io n 19 .4 for details on system clock selection.
The Clock Multiplier is c onfigured via the CLKMUL re gister (SFR Definition 19.4). The procedure for con-
figuring and enabling the Clock Multiplier is as follows:
1. Reset the Multiplier by writing 0x00 to register CLKMUL.
2. Select the Multiplier input source via the MULSEL bits.
3. Select the Multiplier output scaling factor via the MULDIV bits
4. Enable th e Mu ltip lier with the MULEN bit (CLKMUL | = 0x80).
5. Delay for >5 µs.
6. Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
7. Poll for MULRDY => ‘1’.
Important Note: When using an external oscillator as the input to the Clock Multiplier, the external
source must be enabled and stable before the Multiplier is initialized. See Section 19.4 for details
on selecting an external oscillator so urce.
The Clock Multiplier allows faster operation of the CIP-51 core and is intended to generate an output fre-
quency between 25 and 50 MHz. The clock multiplier can also be used with slow input clocks. However, if
the clock is below the minimum Clock Multiplier input frequency (FCMmin) specified in Table 19.1, the gen-
erated clock will consist of four fast pulses followed by a long delay until the next input clock rising edge.
The average frequency of the output is equal to 4x the input, but the instantaneous frequency may be
faster. See Figure 19.3 for more information.
Figure 19.3. Example Clock Multiplier Output
if FCM > FCMmin
in
FCM
in
FCM
out
if FCM < FCM
minin
FCM
out
FCM
in
C8051F410/1/2/3
Rev. 1.1 173
SFR Definition 19.4. CLKMUL: Clock Multiplier Con trol
Note: The maximum SYSCLK is 50 MHz, so the Clock Multiplier outpu t should be scaled accord-
ingly.
Bit7: MULEN: Clock Multiplier Enable
0: Clock Multiplier disabled.
1: Clock Multiplier enabled.
Bit6: MULINIT: Clock Multiplier Initialize
This bit should be a ‘0’ when the Clock Multiplier is enabled. On ce enabled, writing a ‘1’ to
this bit will initialize the Clock Multiplier . The MULRDY bit reads ‘1’ when the Clock Multiplier
is stabilized.
Bit5: MULRDY: Clock Multiplier Ready
This read-only bit indicates the status of the Clock Multiplier.
0: Clock Multiplier not ready.
1: Clock Multiplier ready (locked).
Bits4–2: MULDIV: Clock Multiplier Output Scaling Factor
These bits scale the Clock Multiplier output.
000: Clock Multiplier Output scaled by a factor of 1.
001: Clock Multiplier Output scaled by a factor of 1.
010: Clock Multiplier Output scaled by a factor of 1.
011: Clock Multiplier Outpu t sca le d by a facto r of 2/ 3*.
100: Clock Multiplier Output sca led by a factor of 2/4 (or 1/2).
101: Clock Multiplier Output scaled by a factor of 2/5*.
110: Clock Multiplier Outpu t sca le d by a facto r of 2/ 6 (o r 1/3 ) .
111: Clock Multiplier Output scaled by a factor of 2/7*.
*Note: The Clock Multiplier Output duty cycle is not 50% for these settings.
Bits1–0: MULSEL: Clock Multiplier Input Select
These bits select the clock supplied to the Clock Multiplier.
R/W R/W R R/W R/W R/W R/W R/W Reset Value
MULEN MULINIT MULRDY MULDIV MULSEL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAB
MULSEL Selected Input Clock Clock Multiplier Output
for MULDIV = 000b
00 Internal Oscillator / 2 Internal Oscillator x 2
01 External Oscillator External Oscillator x 4
10 E xte rn al Os cillator / 2 Externa l Osc illato r x 2
11 Internal Oscilla tor Inte rn al Osc i llat or x 4
C8051F410/1/2/3
174 Rev. 1.1
19.4. System Clock Selection
The internal oscillator r equires l ittle st art-u p time and may be selected as the system clock immediately fol-
lowing the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typ-
ically require a start-up time before they are settled and ready for use. The Crystal Valid Flag (XTLVLD in
register OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid reading a
false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external
oscillator and checking XTLVLD. RC and C modes typically require no startup time.
The CLKSL[1:0] bits in register CLKSEL select which oscillator source is used as the system clock.
CLKSL[1:0] must be set to 01b for the system clock to run from the external oscillator; however the exter-
nal oscillator may still clock certain peripherals (timers, PCA) when another oscillator is selected as the
system clock. The system clock may be switched on-the-fly between th e internal oscillator , external oscilla-
tor, smaRTClock oscillator, and Clock Multiplier, as long as the selected clock source is enabled and has
settled.
SFR Definition 19.5. CLKSEL: Clock Select
Bits7–6: Unused. Read = 00b; Write = don’t care.
Bits5–4: CLKDIV1–0: Output /SYSCLK Divide Value
These bits can be used to pre-divide the /SYSCLK output before it is sent to a port pin
through the Crossbar.
00: Output will be SYSCLK.
01: Output will be SYSCLK/2.
10: Output will be SYSCLK/4.
11: Output will be SYSCLK/8.
Bit3: Unused. Read = 0b; Write = don’t care.
Bit2: Reserved. Read = 0b; Must write 0b.
Bits1–0: CLKSL1–0: System Clock Select
These bits select the system clock source.
R R R/W R/W R R/W R/W R/W Reset Value
- - CLKDIV - Reserved CLKSL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA9
CLKSL Selected Clock
00 Internal Oscillator (as determined by the
IFCN bits in register OSCICN)
01 External Oscillator
10 Clock Multiplier
11 smaRTClock Oscillator
C8051F410/1/2/3
Rev. 1.1 175
Table 19.1. Oscillator Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Internal Oscillator Frequency Reset Frequency 24 24.5 25 MHz
Internal Oscillator Supply
Current (from VDD)OSCICN.7 = 1 — 400 — µA
Minimum Clock Multiplier Input
Frequency (FCMmin)T = 25 °C — 1.6 — MHz
C8051F410/1/2/3
176 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 177
20. smaRTClock (Real Time Clock)
C8051F41x devices include a lo w power smaR TClock Pe ripheral (Real Time Clock). The smaRTClock has
a dedicated 32 kHz oscillator that can be co nfigured for use with or without a crystal, a 47-bit smaRTClock
timer with alarm, a backup supply regulator and 64 bytes of battery-backed SRAM. When the backup sup-
ply voltage (VRTC-BACKUP) is powered, the smaRTClock peripheral remains fully functional if the core sup-
ply voltage (VDD) is lost.
The smaRTClock allows a maximum of 137 year 47-bit independent time-keeping when used with a
32.768 kHz Watch Crystal and backup supply voltage of at least 1V. The switchover logic powers smaRT-
Clock from the backup supply when the voltage at VRTC-BACKUP is greater than VDD. The smaRTClock
Alarm and Missing Clock Detector can interrupt the CIP-51, wake the internal oscillator from SUSPEND
mode, or generate a device reset if the smaRTClock timer reaches a pre-set value or the oscillator stops.
Figure 20.1. smaRTClock Block Diagram
64B
Backup RA M
smaRT Clock O scillator
smaRTClock
CIP-51 CPU
XTAL4 XTAL3
Switchover
Logic
RTC0CN
CAPTUREn
ALARMn
RTC0XCN
RAMDATA
RAMADDR
RTC0KEY
RTC0ADR
RTC0DAT
Interface
Registers
Internal
Registers
smaR TClock State Mach ine
Interrupt
Backup
Regulator
VDD
VRTC-BACKUP
47-Bit
smaRTC lock
Timer
C8051F410/1/2/3
178 Rev. 1.1
20.1. smaRTClock Interface
The smaRTClock Interface consists of three registers: RTC0KEY, RTC0ADR, and RTC0DAT. These inter-
face registers are located on the CIP-51’s SFR map and provide access to the smaRTClock internal regis-
ters listed in Table 20.1. The smaRTClock internal registers can only be accessed indirectly through the
smaR TClock Interface.
20.1.1. smaRTClock Lock and Key Functions
The smaRTClock Interface is protected with a lock and key function. The smaRTClock Lock and Key Reg-
ister (RTC0KEY) must be written with the correct key codes, in sequence, before writes and reads to
RTC0ADR and RTC0DAT may be performed. The key codes are: 0xA5, 0xF1. There are no timing restric-
tions, but the key codes must be written in order. If the key co des are written out of order, the wrong codes
are written, or an invalid read or write is attempted, further writes and reads to RTC0ADR and RTC0DAT
will be disabled until the next system reset. Once the smaRTClock interface is unlocked, software may per-
form accesses of the smaRTClock registers until an invalid access, the interface is locked, or a system
reset.
Reading the RTC0KEY register at any time will provide the smaRTClock Interface status and will not inter-
fere with the sequence that is being written. The RTC0KEY register description in SFR Definition 20.1 lists
the definition of each status code .
20.1.2. Using RTC0ADR and RTC0DAT to Access smaRTClock Internal Registers
The smaRTClock internal registers can be read and written using RTC0ADR and RTC0DAT. The
RTC0ADR register selects the smaRTClock in ternal register that will be targeted by subsequent reads or
writes. Prior to each read or write, BUSY (RTC0ADR.7) should be checked to make sure the smaRTClock
Interface is not busy performing another read or write opera tion. A sma RTClock Write oper ation is initiated
by writing to the RTC0DAT register. Below is an example of writ ing to a sm aRTClock intern al re gist er.
Step 1. Poll BUSY (RTC0ADR.7) until it returns a ‘0’.
Step 2. Write 0x06 to RTC0ADR. This selects the internal RTC0CN register at smaRTClock
Address 0x06.
Step 3. Write 0x00 to RTC0DAT. This operation writes 0x00 to the internal RTC0CN register.
An smaRTClock Read operation is initiated by setting the smaRTClock Interface Busy bit. This transfers
the content s of the intern al register selected by R TC0ADR to R TC0DAT. The transferred data will r emain in
RTC0DAT until the next read or write operation. Below is an example of reading a smaRTClock internal
register.
Step 1. Poll BUSY (RTC0ADR.7) until it returns a ‘0’.
Step 2. Write 0x06 to RTC0ADR. This select s the internal RTC0CN register at smaRTClock
Address 0x06.
Step 3. Write ‘1’ to BUSY. This initiates the transfer of data from RTC0CN to RTC0DAT.
Step 4. Poll BUSY (RTC0ADR.7) until it returns a ‘0’.
Step 5. Read data from RTC0DAT. This data is a copy of the RTC0CN register.
Note: The RTC0ADR and RTC0DAT registers will retain their state upon a device reset.
20.1.3. smaRTClock Interface Autoread Feature
When Autoread is enabled, each read from RTC0DAT initiates the next indirect read operation on the
smaRTClock intern al register selected by RTC0ADR. Software should set the BUSY bit once at the begin-
C8051F410/1/2/3
Rev. 1.1 179
ning of each series of consecutive reads. Software must check if the smaRTClock Interface is busy prior to
reading RTC0DAT. Autoread is enabled by setting AUTORD (RTC0ADR.6) to logic 1.
20.1.4. RTC0ADR Autoincrement Feature
For ease of reading and writing the 48-bit CAPTURE and ALARM values, RTC0ADR automatically incre-
ments after each read or write to a CAPTUREn or ALARMn register. This speeds up the pro cess of settin g
an alarm or reading the current smaRTClock timer value.
Table 20.1. smaRTClock Internal Registers
smaRTClock
Address smaRTClock
Register Register Name Description
0x00 - 0x05 CAPTUREn smaRTClock Capture
Registers Six Registers used for setting the 47-bit
smaRTClock tim er or reading its current
value. The LSB of CAPTURE0 is not used.
0x06 RTC0CN smaRTClock Control
Register Controls the operation of the smaRTClock
State Machin e.
0x07 RTC0XCN smaRTClock Oscillator
Control Register Controls the operation of the smaRTClock
Oscillator.
0x08–0x0D ALARMn smaRTClock Alarm
Registers Six registers used to set or read the 47-bit
smaRTClock alarm value. The LSB of
ALARM0 is not used.
0x0E RAMADDR smaRTClock Backup RAM
Indirect Address Register Used as an index to the 64 byte smaRTClock
backup RAM.
0x0F RAMDATA smaRTClock Backup RAM
Indirect Data Register Used to read or write the byte pointed to by
RAMADDR.
C8051F410/1/2/3
180 Rev. 1.1
SFR Definition 20.1. RTC0KEY: smaRTClock Lock and Key
Bits 7–0: RTC0STATE. smaRTClock State Bits
Read:
0x00: smaRTClock Inte rf ac e is locke d .
0x01: smaRTClock Inte rf ac e is locked. First key code (0xA5) has been written, waiting for
second key code.
0x02: smaRTClock Interface is unlocked. First and second key codes (0xA5, 0xF1) have
been written.
0x03: smaRTClock Interface is disabled until the next system reset.
Write:
When RTC0ST ATE = 0x00 (locked), writing 0xA5 followed by 0xF1 unlocks the smaRTClock
Interface.
When RTC0STATE = 0x01 (waiting for second key code), writing any value other than the
second key code (0xF1) will change RTC0STATE to 0x03 and disable the smaRTClock
Interface until the next system reset.
When RTC0STATE = 0x02 (unlocked), any write to RTC0KEY will lock the smaRTClock
Interface.
When RTC0STATE = 0x03 (disabled), writes to RTC0KEY have no effect.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAE
C8051F410/1/2/3
Rev. 1.1 181
SFR Definition 20.2. RTC0ADR: smaRTClock Address
Bit 7: BUSY: smaRTClock Interface Busy bit.
Writing a ‘1’ to this bit initiates a smaRTClock indirect read operation. This bit is automati-
cally cleared by hardware when the operation is complete.
0: smaRTClock Interface is not busy.
1: smaRTClock Interface is busy performing a read or write operation.
Bit 6: AUTORD: smaRTClock Interface Aut o Read Enab le .
0: BUSY must be written manually for each smaRTClock indirect read operation.
1: The next smaR TClock indirect read operation is initiated when RTC0DAT is read by soft-
ware.
Bit 5: VREGEN: Backup Supply Voltage Regulator Enable.
This bit is automatically set to 1b when VRTC-BACKUP > VDD.
0: Backup Supply Voltage Regulator Disabled (smaRTClock powered from VDD).
1: Force Backup Supply Voltage Regulator Enabled (smaRTClock po wered from VRTC-
BACKUP).
Bit 4: SHORT: Short Read/Write Timing Enable.
0: smaRTClock reads and writes are 4 system clocks wide.
1: smaRTClock reads and writes are 1 system clock wide.
Note: Increasing the speed of the smaRTClock reads and writes may also slightly increase
power consum p tion .
Bits 3–0: RTC0ADDR: smaRTClock Address Bits
These bits select the smaRTClock internal register that is targeted by reads/writes to
RTC0DAT.
Note: The RTC0ADDR bits increment after each indirect read/write operation that
targets a CAPTUREn or ALARMn internal register.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
BUSY AUTORD VREGEN SHORT RTC0ADDR Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAC
RTC0ADDR smaRTClock Internal Regi ster
0000 CAPTURE0
0001 CAPTURE1
0010 CAPTURE2
0011 CAPTURE3
0100 CAPTURE4
0101 CAPTURE5
0110 RTC0CN
0111 RTC0XCN
1000 ALARM0
1001 ALARM1
1010 ALARM2
1011 ALARM3
1100 ALARM4
1101 ALARM5
1110 RAMADDR
1111 RAMDATA
C8051F410/1/2/3
182 Rev. 1.1
SFR Definition 20.3. RTC0DAT: smaRTClock Data
20.2. smaRTClock Clocking Sources
The smaRTClock peripheral is clocked from its own timebase, independent of SYSCLK. The RTCCLK
timebase is derived from the smaRTClock oscillator circuit. This oscillator has two modes of operation:
Crystal Mode, and Self-Oscillate Mode. The oscillation frequency is 32.768 kHz in Crystal Mode and can
be configured to roughly 20 kHz or 40 kHz in Self-Oscillate Mode. The frequency of the smaRTClock oscil-
lator can be measured with respect to another oscillator using Timer 2 or Timer 3. Section
“24.2.3. External/smaRTClock Capture Mode” on page 241 shows how this can be accomplished.
Note: The smaRTClock clock can be selected as system clock and routed to a port pin. See SFR
Definition 19.5. “CLKSEL: Clock Select” on page 174 and Section “18. Port Input/Output” on page 147.
20.2.1. Using the smaRTClock Oscillator in Crystal Mode
When using Crystal Mode, a 32.768 kHz crystal should be connected between XTAL3 and XTAL4. No
other external components are required. The following steps show how to start the smaRTClock crystal
oscillator in software:
Step 1. Set smaRTClock to Crystal Mode (XMODE = 1).
Step 2. Optional. Enable Automatic Gain Control (AGCEN = 1).
Step 3. Optional. Enable smaRTClock Bias Doubling (BIASX2 = 1).
Step 4. Enable power to the smaRTClock oscillator circuit (RTC0EN = 1).
Step 5. Poll the smaRTClock Clock Valid Bit (CLKVLD) until the crystal oscillator stabilizes.
Step 6. Optional. Clear BIASX2 to ‘0’ after the oscillator stabilizes to conserve power.
20.2.2. Using the smaRTClock Oscillator in Self-Oscillate Mode
When using Self-Oscillate Mode, the XTAL3 and XTAL4 pins should be shorted together. The following
steps show how to configure smaRTClock for use in Self-Oscillate Mode:
Step 1. Set smaRTClock to Self-Oscillate Mode (XMODE = 0).
Step 2. Set the desired oscillation frequency:
For oscillation at about 20 kHz, set BIASX2 = 0.
For oscillation at about 40 kHz, set BIASX2 = 1.
Step 3. The oscillator starts oscillating instantaneously.
Note: Software should avoid read modify write instructions when writing values to RTC0DAT.
Bits 7–0: RTC0DAT. smaRTClock Data Bits
Holds data transferred to/from the internal smaRTClo ck register selected by RTC0ADR.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAD
C8051F410/1/2/3
Rev. 1.1 183
20.2.3. Automatic Gain Control (Crystal Mode Only)
Automatic Gain Control is enabled by setting AGCEN (RTC0XCN.7) to a logic 1. When enabled, the
smaRTClock oscillator trims the oscillation amplitude to save power. This mode is useful for preserving
battery life in systems where oscillator performance is not critical and external conditions are stable.
Note: Setting the AGCEN to a logic 1 in self-oscillator mode can lead to drastic changes in the smaRT-
Clock oscillator freq u en cy.
20.2.4. smaRTClock Bias Doubling
The smaRTClock Bias Doubling is enabled by setting BIASX2 (RTC0XCN.5) to 1b. When enabled, the
bias current to smaRTClock is doubled allowing for more robust oscillator performance. When the smaRT-
Clock oscillator is in Self-Oscillate mode, the oscillation frequency is increased from 20 to 40 kHz. When
operating in Crystal Mode, the oscillator is less likely to be affected by external conditions when
BIASX2 = ‘1’. Enabling Bias Doubling increases the power co nsumption of smaR TClock; ther efore, it is not
recommended for use in power-critical systems.
20.2.5. smaRTClock Missing Clock Detector
The smaRTClock Missing Clock Detector is a one-shot circuit enabled by setting MCLKEN (RTC0CN.6) to
a logic 1. When the smaR TClo ck Missing Clock Detector is e nabled, OSCFAIL (R TC0CN.5) is set by har d-
ware if RTCCLK remains high or low for more than 50 µs. A smaRTClock Missing Clock detector timeout
triggers three events:
1. Awakening the internal oscillator from Suspend Mode.
2. smaRTClock Interrupt (If the smaRTClock Interrupt is enabled).
3. MCU reset (If smaRTClock is enabled as a reset source).
Note: The smaR TClock Missing Clock Detector should be disabled when making changes to the oscillator
settings in RTC0XCN.
C8051F410/1/2/3
184 Rev. 1.1
Internal Register Definition 20.4. RTC0CN: smaRTClock Control
Bit 7: RTC0EN: smaRTClock Enable Bit.
0: smaRTClock bias and crystal oscillator disabled. smaRTClock is powered from VDD only.
1: smaRTClock bias and crystal oscillator enabled. smaRTClock can switch to the backup
battery if VDD fails.
Bit 6: MCLKEN: smaRTClock Missing Clock Detector Enable Bit.
When enabled, the smaRTClock missing clock detector sets the OSCFAIL bit if the smaRT-
Clock clock frequency falls below approximately 20 kHz.
0: smaRTClock missing clock detector disabled.
1: smaRTClock missing clock detector enabled.
Bit 5: OSCFAIL: smaRTClock Clock Fail Flag.
Set by hardware when a missing clock detector timeout occurs. When the smaRTClock
Interrupt is enabled, settin g this bit causes the CPU to vector to the smaRTClock interrupt
service routine. This bit is not automatically cleared by hardwa re.
Bit 4: RTC0TR: smaRTClock Timer Run Control.
0: smaRTClock timer holds its current value.
1: smaRTClock timer increments every smaRTClock clock period.
Bit 3: RTC0AEN: smaRTClock Alarm Enable.
0: smaRTClock alar m events disabled.
1: smaRTClock alarm events enabled.
Bit 2: ALRM: smaRTClock Alarm Event Flag.
Set by hardware when the smaR TClock timer value is grea ter than or equal to the value of
the ALARMn registers. When the smaRTClock Interrupt is enabled, setting this bit causes
the CPU to vector to the smaRTClock interrupt se rvic e ro utine. This bit is not automatically
cleared by hardware.
Bit 1: RTC0SET: smaRTClock Set Bit.
Writing a ‘1’ to this bit causes the 47-bit value in CAPTUREn registers to be transferred to
the smaRTClock timer. This bit is automatically cleared by hardware once the transfer is
complete.
Bit 0: RTC0CAP: smaRTClock Capture Bit.
Writing a ‘1’ to this bit causes the 47-bit smaRTClock timer value to be transferred to the
CAPTUREn registers. This bit is automatically cleared by hardware once the transfer is
complete.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
RTC0EN MCLKEN OSCFAIL RTC0TR RTC0AEN ALRM RTC0SET RTC0CAP Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 smaRTClock
Address:
Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. 0x06
C8051F410/1/2/3
Rev. 1.1 185
Internal Register Definition 20.5. RTC0XCN: smaRTClock Oscillator Control
20.3. smaRTClock Timer and Alarm Function
The smaRTClock timer is a 47-bit counter that, when running (RTC0TR = 1), is incremented every RTC-
CLK cycle. The timer has an alarm function that can be set to generate an interrupt, reset the MCU, or
release the internal oscillator from Suspend Mode at a specific time.
20.3.1. Setting and Reading the smaRTClock Timer Value
The 47-bit smaRTClock timer can be set or read using the six CAPTUREn internal registers. Note that the
timer does not need to be stopped before reading or setting its value. The following steps can be used to
set the timer value:
Step 1. Write the desired 47-bit set value to the CAPTUREn registers (the LSB of CAPTURE0 is
not used).
Step 2. Write ‘1’ to RTC0SET. This will transfer the contents of the CAPTUREn registers to the
timer.
Step 3. Operation is complete when RTC0SET is cleared to ‘0’ by hardware.
Bit 7: AGCEN: Crystal Oscillator Automatic Gain Control Enable Bit (Crystal Mode only).
0: Automatic Gain Control disabled.
1: Automatic Gain Control enabled.
Bit 6: XMODE: smaRTClock Mode Select Bit.
This bit selects wh ether smaRTClock will be used with or with out a crystal.
0: smaRTClock is configured to Self-Oscillate Mode.
1: smaRTClock is configured to Crystal Mode.
Bit 5: BIASX2: smaRTClock Bias Double Enable Bit.
0: smaRTClock Bias Current Doubling is disabled.
1: smaRTClock Bias Current Doubling is enabled.
Bit 4: CLKVLD: smaRTClock Clock Valid Bit.
Set by hardware when the smaRTClock crystal oscillator is nearly stable. This bit always
reads 1b when smaRTClock is used in Self-Oscillate Mode (XMODE = 0). This bit should be
checked at least 1 ms after enabling the smaRTClock oscilla tor circu it an d sh ou ld no t be
used for an oscillator fail detect (use OSCFAIL in RTC0CN instead).
Bits 3–1: UNUSED. Read = 000b. Write = don’t care.
Bit 0: VBATEN: smaRTClock VBAT Indicator.
Note: This bit always reads 1b when smaRTClock is disabled (RTC0EN = 0).
For smaRTClock enabled (RTC0EN = 1):
0: smaRTClock is powered from VDD.
1: smaRTClock i s powered from the VRTC-BACKUP supply.
R/W R/W R/W R R R R R Reset Value
AGCEN XMODE BIASX2 CLKVLD - - - VBATEN Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 smaRTClock
Address:
Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. 0x07
C8051F410/1/2/3
186 Rev. 1.1
The following steps can be used to read the current timer value:
Step 1. Write ‘1’ to RTC0CAP. This will transfer the contents of the timer to the CAPTUREn
registers (the LSB of the sm aRTClock time r will be foun d in CAPT URE0.1).
Step 2. Poll RTC0CAP until it is cleared to ‘0’ by hardware.
Step 3. A snapshot of the timer value can be read from the CAPTUREn registers
20.3.2. Setting a smaRTClock Alarm
The smaRTClock Alarm function compares the 47-bit value of smaRTClock Timer to the value of the
ALARMn registers. An alarm event is triggered if the smaRTClock timer is greater than or equal to the
ALARMn registers. If the smaR TClock Interrupt is enab led, the CIP- 51 will ve ctor to the smaR TClock Inte r-
rupt Service Routine when an alarm event occurs. If smaRTClock is enabled as a reset source, the MCU
will be reset when an alarm event occurs. Also, the internal oscillator will awaken fr om su sp en d mode o n a
smaRTClock alarm event.
The following step s can be used to set up a smaRTClock Alarm:
Step 1. Disable smaRTClock Alarm Events (RTC0AEN = 0).
Step 2. Set the ALARMn registers to the desired value.
Step 3. Enable smaRTClock Alarm Events (RTC0AEN = 1).
Note: When an alarm event occurs and smaRTClock interrupts are enabled, software should clear the
ALRM bit and set the ALARM5-0 registers to the maximum possible value to avoid continuous alarm inter-
rupts.
Internal Register Definition 20.6. CAPTUREn: smaRTClock T imer Capture
Bits 7–0: CAPTUREn: smaRTClock Set/Capture Value.
These 6 registers (CAPTURE5–CAPTURE0) are used to read or set the 47-bit smaR TClock
timer . Da ta is transferred to or fr om the smaRTClock timer when the RTC0SET or R TC0CAP
bits are set.
Note: The LSB of CAPTURE0 is not used. The LSB of the 47-bit smaRTClock timer will appear in
CAPTURE0.1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
smaRTClock Addresses: CAPTURE0: 0x00; CAPTURE1: 0x01; CAPTURE2: 0x02; CAPTURE3: 0x03; CAPTURE4: 0x04; CAPTURE5:
0x05
Note: These registers are not SFRs. They can only be accessed indirectly through RTC0ADR and RTC0DAT.
C8051F410/1/2/3
Rev. 1.1 187
Internal Register Definition 20.7. ALARMn: smaRTClock Alarm
20.4. Backup Regulator and RAM
The smaRTClock includes a backup supply regulator that keeps the smaRTClock peripheral fully func-
tional when VDD is turned off. The backup supply regulator regulates the VRTC-BACKUP supply voltage,
which can range from 1 V to 5.25 V. Switchover logic automatically powers smaRTClock from the backup
supply when the voltage at VRTC-BACKUP is greater than VDD.
The smaRTClock also includes 64 bytes of backup RAM. This memory can be read and written indirectly
using the RAMADDR and RAMDATA internal registers.
Internal Register Definition 20.8. RAMADDR: smaRTClock Backup RAM Address
Bits 7–0: ALARMn: smaRTClock Alarm Target.
These 6 registers (ALA RM5–ALARM0) are used to set an alarm event for the smaRTClock
timer. The smaRTClock alarm should be disabled (RTC0AEN=0) when updating these reg-
isters.
Note: The LSB of ALARM0 is not used. The LSB of the 47-bit smaRTClock timer will be compared
against ALARM0.1.
R/W R/W R/W R/W R/W R/W R/W R/W Res e t Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
smaRTClock Addresses: ALARM0: 0x08; ALARM1: 0x09; ALARM2: 0x0A; ALARM3: 0x0B; ALARM4: 0x0C; ALARM5: 0x0D
Note: These registers are not SFRs. They can only be accessed indirectly through RTC0ADR and R TC0DAT.
Bit 7: RAMADDR: smaRTClock Battery Backup RAM Address Bits
These bits select the smaRTClock Backup RAM byte that is targeted by RAMDATA. This
address auto-in crements after each read or write of RAMDATA.
R/W R/W R/W R/W R/W R/W R/W R/W Res e t Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 smaRTClock
Address:
Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. 0x0E
C8051F410/1/2/3
188 Rev. 1.1
Internal Register Definition 20.9. RAMDATA: smaRTClock Backup RAM Data
Reads and writes of RAMDATA load the value at address RAMADDR into RTC0DAT. The following exam-
ple writes 0xA5 to address 0x20 in the RAM and reads the value back to a temporary variable:
// in 'C':
unsigned char temp = 0x00;
// Unlock the smaRTClock interface
RTC0KEY = 0xA5;
RTC0KEY = 0xF1;
// Enable the smaRTClock
RTC0ADR = 0x06; // address the RTC0CN register
RTC0DAT = 0x80; // enable the smaRTClock
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
// Write to the smaRTClock RAM
RTC0ADR = 0x0E;// address the RAMADDR register
RTC0DAT = 0x20;// write the address of 0x20 to RAMADDR
while ((RTC0ADR & 0x80) == 0x80);// poll on the BUSY bit
RTC0ADR = 0x0F;// address the RAMDATA register
RTC0DAT = 0xA5;// write 0xA5 to RAM address 0x20
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
// Read from the smaRTClock RAM
RTC0ADR = 0x0E;// address the RAMADDR register
RTC0DAT = 0x20;// write the address of 0x20 to RAMADDR
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
RTC0ADR = 0x0F; // address the RAMDATA register
RTC0ADR |= 0x80; // initiate a read of the RAMDATA register
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
temp = RTC0DAT; // read the value of RAM address 0x20
; in assembly:
; Unlock the smaRTClock interface
mov RTC0KEY, #0A5h
mov RTC0KEY, #0F1h
Bit 7: RAMDATA: smaRTClock Battery Backup RAM Data Bits.
These bits provide read and write access to the smaRTClock Backup RAM byte that is
selected by RAMADDR.
R/W R/W R/W R/W R/W R/W R/W R/W Res e t Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 smaRTClock
Address:
Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. 0x0F
C8051F410/1/2/3
Rev. 1.1 189
; Enable the smaRTClock
mov RTC0ADR, #06h ; address the RTC0CN register
mov RTC0DAT, #080h ; enable the smaRTClock
L0: mov A, RTC0ADR ; poll on the BUSY bit
jb ACC.7, L0
; Write to the smaRTClock RAM
mov RTC0ADR, #0Eh; address the RAMADDR register
mov RTC0DAT, #20h; write the address of 0x20 to RAMADDR
L1: mov A, RTC0ADR ; poll on the BUSY bit
jb ACC.7, L1
mov RTC0ADR, #0Fh; address the RAMDATA register
mov RTC0DAT, #0A5h; write 0xA5 to RAM address 0x20
L2: mov A, RTC0ADR ; poll on the BUSY bit
jb ACC.7, L2
; Read from the smaRTClock RAM
mov RTC0ADR, #0Eh; address the RAMADDR register
mov RTC0DAT, #20h; write the address of 0x20 to RAMADDR
L3: mov A, RTC0ADR ; poll on the BUSY bit
jb ACC.7, L3
mov RTC0ADR, #0Fh ; address the RAMDATA register
orl RTC0ADR, #80h ; initiate a read of the RAMDATA register
L4: mov A, RTC0ADR ; poll on the BUSY bit
jb ACC.7, L4
movR0, #80h
mov@R0, RTC0DAT ; read the value of RAM address 0x20 into
; the 128-byte internal RAM
To reduce the number of instructions necessary to read and write sections of the 64-byte RAM, the
RAMADDR register automatically increments after each write or read. The following C example initializes
the entire 64-byte RAM to 0xA5 and copies this value from the RAM to an array using the auto-increment
feature:
// in 'C':
unsigned char RAM_data[64] = 0x00;
unsigned char addr;
// Unlock smaRTClock, enable smaRTClock
// Write to the entire smaRTClock RAM
RTC0ADR = 0x0E;// address the RAMADDR register
RTC0DAT = 0x00;// write the address of 0x00 to RAMADDR
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
RTC0ADR = 0x0F;// address the RAMDATA register
for (addr = 0; addr < 64; addr++)
{
RTC0DAT = 0xA5; // write 0xA5 to every RAM address
while ((RTC0ADR & 0x80) == 0x80);// poll on the BUSY bit
}
// Read from the entire smaRTClock RAM
RTC0ADR = 0x0E;// address the RAMADDR register
C8051F410/1/2/3
190 Rev. 1.1
RTC0DAT = 0x00;// write the address of 0x00 to RAMADDR
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
RTC0ADR = 0x0F; // address the RAMDATA register
for (addr = 0; addr < 64; addr++)
{
RTC0ADR |= 0x80; // initiate a read of the RAMDATA register
while ((RTC0ADR & 0x80) == 0x80); // poll on the BUSY bit
RAM_data[addr] = RTC0DAT; // copy the data from the entire RAM
}
C8051F410/1/2/3
Rev. 1.1 191
21. 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 2, 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 1/20th of the system clock as a master or slave
(this can be faster than allowed by the SMBus specification, depending on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface m ay opera te as a ma ster an d/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.
Figure 21.1. SMBus Block Diagram
Data Path
Control
SMBUS CONTROL LOGIC
C
R
O
S
S
B
A
R
SCL
FILTER
N
SDA
Control
SCL
Control
Arbitration
SCL Synchroni zation
IRQ Generation
SCL Generation (Master Mode)
SDA Control
Interrupt
Request
Port I/O
SMB0CN
S
T
A
A
C
K
R
Q
A
R
B
L
O
S
T
A
C
K
S
I
T
X
M
O
D
E
M
A
S
T
E
R
S
T
O
01
00
10
11
T0 Overflow
T1 Overflow
TMR2H Overflo w
TMR2L Overflow
SMB0CF
E
N
S
M
B
I
N
H
B
U
S
Y
E
X
T
H
O
L
D
S
M
B
T
O
E
S
M
B
F
T
E
S
M
B
C
S
1
S
M
B
C
S
0
01234567 SMB0DAT SDA
FILTER
N
C8051F410/1/2/3
192 Rev. 1.1
21.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C Manual (AN10216-01), Philips Semiconductor.
2. System Management Bus Specification -- Version 2, SBS Implementers Forum.
21.2. SMBus Configuration
Figure 21.2 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 di f feren t voltag e 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 th e bus is limited o nly by th e re quirem ent that the r ise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
Figure 21.2. Typical SMBus Configuration
Note: It is recommended that the SDA and SCL pins be configured for high impedance overdrive mode.
See Section “18. Port Input/Output” on page 147 for more information.
21.3. 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 arbi tration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
VSupply = 5 V
Master
Device Slave
Device 1 Slave
Device 2
VSupply = 3 V VSupply = 5 V VSupply = 3 V
SDA
SCL
C8051F410/1/2/3
Rev. 1.1 193
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 21.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowl-
edge), which is a high SDA during a high SCL.
The direction bi t (R/W) occupies the least-significan t bit position of the address byte. The d irection bit is set
to logic 1 to indicate a "READ" operation and cleare d 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 21.3 illustrates a typical
SMBus transaction.
Figure 21.3. SMBus Transaction
21.3.1. Arbitration
A master may star t a transfer on ly if the bus is free. The b us is free af ter a STOP condition or af ter the SCL
and SDA lines remain high for a specified time (see Section “21.3.4. SCL High (SMBus Free) Timeout”
on page 194). 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 maste r a ttem pting the HIGH wi ll 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.
21.3.2. 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.
SLA6
SDA SLA5-0 R/W D7 D6-0
SCL
Slave Address + R/W Data ByteSTART ACK NACK STOP
C8051F410/1/2/3
194 Rev. 1.1
21.3.3. SCL Low Timeout
If the SCL line is held low b y a slave device on the bus, n o further communica tion is possible . Furthermore,
the master ca nnot for ce the SCL lin e high t o correc t 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 3 is used to detect SCL low time outs. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the T imer 3 interrupt ser vice routine ca n be used to rese t (disable
and re-enable) the SMBus in the event of an SCL low timeout.
21.3.4. 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 a s free . When the SMBF TE bit in SM B0 CF is se t, th e b us will be co n sid er ed fr ee if SC L a nd
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the STAR T will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation. Enabling the Bus Free Timeout is recom-
mended.
21.4. 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 conf igura tio n re gis te r
• START/STOP timing, detection, and generation
• Bus arbitration
• Interrupt generation
• Status information
SMBus interrupt s are genera ted for ea ch 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 “21.5. SMBus Transfer Modes” on page 201 for more details on transmission
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“21.4.2. SMB0CN Control Register” on page 198; Table 21.4 provides a quick SMB0CN decoding refer-
ence.
C8051F410/1/2/3
Rev. 1.1 195
SMBus configuration options include:
• Timeout detection (SCL Low Timeout and/or Bus Free Timeout)
• SDA setup and hold time extensions
• Slave event en ab le /d isab le
• Clock source selection
These options are selected in the SMB0CF register, as described in Section “21.4.1. SMBus Configura-
tion Register” on page 195.
21.4.1. 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 addre sses and will no t generate an y slave interru pt s. When the INH bit
is set, all slave events will be inh i bited following the next START (interrupts will continue for the duration of
the current tra ns fe r) .
The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or
when the Bus Free T ime out detection is enabled. When oper ating as a master, overflows from the selected
source determine the absolu te minimum SCL low and high times as defined in Equation 21.1. 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 covere d in Section “24. Timers” on page 231.
Equation 21.1. 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 21.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus ), th e typ ical SMBus bit rate is approximated by Equation 21.2.
Equation 21.2. Typical SMBus Bit Rate
Table 21.1. SMBus Clock Source Selection
SMBCS1 SMBCS0 SMBus Clock Source
0 0 Timer 0 Overflow
0 1 Timer 1 Overflow
1 0 Timer 2 High Byte Overflow
1 1 Timer 2 Low Byte Overflow
THighMin TLowMin 1
fClockSourceOverflow
----------------------------------------------
==
BitRate fClockSourceOverflow
3
----------------------------------------------
=
C8051F410/1/2/3
196 Rev. 1.1
Figure 21.4 shows the typical SCL generation described by Equation 21.2. 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 mast er will neve r exc ee d the lim its defined by equ ati on Equation 21.1.
Figure 21.4. 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 fro m low-to-high.
The minimum SDA hold time defin es the absolute minimum time that the curre nt SDA value remains stabl e
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 n s and 300 ns, re spective ly. Table 21.2 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.
Note: For SCL ope ra t io n ab ov e 10 0 kHz, EXTHOLD should be cleared to ‘0’.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “21.3.3. SCL Low Timeout” on page 194). The SMBus interface will force T imer 3
to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service r ou-
tine should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 21.4). 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). Enabling the Bus Fre e Timeout is recommended.
Table 21.2. Minimum SDA Setup and Hold Times
EXTHOLD Minimum SDA Setup T ime Minimum SDA Hold Time
0
Tlow - 4 system clocks
OR
1 system clock + s/w delay*
3 system clocks
1 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.
SCL
Timer Source
Overflows
SCL High Ti meoutT
Low
T
High
C8051F410/1/2/3
Rev. 1.1 197
SFR Definition 21.1. SMB0CF: SMBus Clock/Configuration
Bit7: ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enabled, the inter face 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 bu s. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5: BUSY: SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0
when a STOP or free-timeout is sensed.
Bit4: EXTHOLD: SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and ho ld times according to Table 21.2.
0: SDA Extended Setup and Hold T imes disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3: SMBTOE: SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to
reload while SCL is hi gh and allows T imer 3 to count when SCL goes low. T imer 3 should be
programmed to generate interrupts at 25 ms, and the T imer 3 interrupt service routine
should reset SMBus communication.
Bit2: SMBFTE: SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain hig h 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 21.1.
R/W R/W R R/W R/W R/W R/W R/W Reset Value
ENSMB INH BUSY EXTHOLD SMBTOE SMBFTE SMBCS1 SMBCS0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC1
SMBCS1 SMBCS0 SMBus Clock Source
0 0 Timer 0 Over flo w
0 1 Timer 1 Over flo w
1 0 Timer 2 High Byte Overflow
1 1 Timer 2 Lo w Byte Overflow
C8051F410/1/2/3
198 Rev. 1.1
21.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 21.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO ar e also used to gene ra te START and STOP conditions when operating as a mas-
ter. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mod e and gener ate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. A CKRQ 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 beginn ing and end of each transfe r, after each byte frame, or
when an arbitration is lost; see Table 21.3 for more details.
Import ant Note About the SI Bit: The SMBus inte rface is st alled while SI i s set; thu s SCL is he ld low, and
the bus is stalled until software clears SI.
Table 21.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 21.4 for SMBus sta-
tus decoding using the SMB0CN register.
C8051F410/1/2/3
Rev. 1.1 199
SFR Definition 21.2. SMB0CN: SMBus Control
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.
Bit6: TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
Bit5: 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 b us
is not free, the START is transmitted after a STOP is received or a timeout is detected). If
STA is set by sof tware as an active Master, a repeated START will be generated afte r the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Star t detected.
Bit4: ST O: SMBus Stop Flag. If set by hardware, this bit must be cleared by software.
Write:
0: No STOP conditio n is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmit te d after the next ACK
cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA
and STO are set, a STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (i f in Master Mode).
Bit3: 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.
Bit2: 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.
Bit1: ACK: SMBus Acknowledge Flag.
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 r eceived (if in Transmitter Mode) OR will be transm itted (if
in Receiver Mode).
1: An "acknowledge" h as been received ( if in Transmitter Mode) OR will be tra nsmitted (if in
Receiver Mode).
Bit0: SI: SMBus Interrupt Flag.
This bit is set by hardware unde r the conditions listed in Table 21.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
R R R/W R/W R R R/W R/W Reset Value
MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xC0
C8051F410/1/2/3
200 Rev. 1.1
Table 21.3. Sources for Hardware Changes to SMB0CN
Bit Set by Hardware When: Cleared by Hardware When:
MASTER • A START is generated. • A STOP is generated.
• Arbitration is lost.
TXMODE
• START is generated.
• SMB0DAT is written before the start of an
SMBus frame.
• A START is detected.
• Arbitration is lost.
• SMB0DAT is not written before the
start of an SMBus fram e.
STA • A START followed by an address byte is
received. • Must be cleared by software.
STO • A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A pending STOP is generated.
• If STO is set by hardware, it must be
cleared by software.
ACKRQ • A byte has been received and an ACK
response value is needed. • After each ACK cycle.
ARBLOST
• A repeated START is detected as a MASTER
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).
• Each time SI is cleared.
ACK • The incoming ACK value is low (ACKNOWL-
EDGE). • The incoming ACK value is high (NOT
ACKNOWLEDGE).
SI
• A START has been generated.
• Lost arbitration.
• A byte has been transmitted and an
ACK/NACK received.
• A byte has been received.
• A START or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
• Must be cleared by software.
C8051F410/1/2/3
Rev. 1.1 201
21.4.3. Data Re gister
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Sof tware may safely rea d or write to the da ta register when the SI flag is set. Software should not
attempt to ac cess the SMB0 DAT register wh en the SM Bus is enable d 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 co ntains the last data byte prese nt on the bu s. In th e even t of lost arb i-
tration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 21.3. SMB0DAT: SMBus Data
21.5. SMBus Transfer Modes
The SMBus interface may be configu red to operate as mast er and /or slave. At any p articular 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 M aster Mo d e any time a START is genera ted, an d rem ains i n
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operat-
ing as a receiver, and after the ACK cycle when operating as a transmitter.
21.5.1. 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 21.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any
number of bytes may be transmitt ed. Notice t hat the ‘data byte transferred ’ interrup ts occur after the ACK
cycle in this mode.
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 1. The serial data in the register remains stable as long as the SI flag is set. When the
SI flag is not set, the system may be in the process of shifting data in/out and the CPU
should not attempt to access this register.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC2
C8051F410/1/2/3
202 Rev. 1.1
Figure 21.5. Typical Master Transmitter Sequence
21.5.2. 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 dat a 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 exit s Master Receiver Mode after the ST O 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 21.6 shows a typical Master Receiver sequence. Two received
data bytes ar e shown, tho ugh a ny numbe r of bytes may be received. Notice that the ‘data byte transferred’
interrupts occur before the ACK cycle in this mode.
Figure 21.6. Typical Master Receiver Sequence
A AAS W PData Byte Data ByteSLA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
Data ByteData Byte A NAS R PSLA
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
C8051F410/1/2/3
Rev. 1.1 203
21.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the inter face en ters Slav e Rece iver Mo de wh en a START followed by a slav e add ress and direc tion b it
(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. Sof tware must write the ACK bit af ter each received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 21.7 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.
Figure 21.7. Typical Slave Receiver Sequence
PWSLASData ByteData Byte A AA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
C8051F410/1/2/3
204 Rev. 1.1
21.5.4. 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 en ters Slave Receiver Mode ( to receive the sla ve address) when a START followed by a
slave address and direction bit (READ in this case) is received. Upo n ente ring Sla ve Transmitter Mode, an
interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an
ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave
interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data
should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and trans-
mits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the
acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is
a NACK, SMB0DAT should not be written to before SI is cleared (Not e: an error cond ition may be gener -
ated 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 21.8 shows a typic al Slave
Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be trans-
mitted. Notice that the ‘data byte transfe rr e d’ inte rr u pts occur after the ACK cycle in this mode.
Figure 21.8. Typical Slave Transmitter Sequence
21.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform to the SMBus specification. Highligh ted re sponse s ar e allowed but do no t confor m to
the SMBus specification.
PRSLASData ByteData Byte A NA
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
C8051F410/1/2/3
Rev. 1.1 205
Table 21.4. SMBus Status Decoding
Mode
Values Read
Current SMbus State Typical Response Options
Values
Written
Status
Vector
ACKRQ
ARBLOST
ACK
STA
STO
ACK
Master Transmitter
1110 0 0 X A master START was generated. Load slave address + R/W
into SMB0DAT. 0 0 X
1100
000
A master data or address byte
was transmitted; NACK received. Set STA to restart transfer. 1 0 X
Abort transfer. 0 1 X
001
A master data or address byte
was transmitted; ACK received.
Load next data byte into
SMB0DAT. 0 0 X
End transfer with STOP. 0 1 X
End transfer with STOP and
start another transfer. 1 1 X
Send repeated START. 1 0 X
Switch to Master Receiver
Mode (clear SI without writ-
ing new data to SMB0DAT). 0 0 X
Master Receiver
1000 1 0 X A master data byte was re ceived;
ACK requested.
Acknowledge received byte;
Read SMB0DAT. 001
Send NACK to indicate last
byte, and send STOP. 010
Send NACK to indicate last
byte, and send STOP fol-
lowed by START. 110
Send ACK followed by
repeated START. 101
Send NACK to indicate last
byte, and send repeated
START. 1 0 0
Send ACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0 0 1
Send NACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0 0 0
C8051F410/1/2/3
206 Rev. 1.1
Slave Transmitter
0100
000
A slave byte was transmitted;
NACK received. No action required (expect-
ing STOP condition). 0 0 X
001
A slave byte was transmitted;
ACK received. Load SMB0DAT with next
data byte to transmit. 0 0 X
01X
A Slave byte was transmitted;
error detected. No action required (expect-
ing Master to end transfer). 0 0 X
0101 0 X X An illegal STOP or bus error was
detected while a Slave Transmis-
sion was in progress. Clear STO. 0 0 X
Slave Receiver
0010
10X
A slave address was received;
ACK requested.
Acknowledge received
address. 001
Do not acknowledge
received address. 000
11X
Lost arbitration as master; slave
address received; ACK
requested.
Acknowledge received
address. 001
Do not acknowledge
received address. 000
Reschedule failed transfer;
do not acknowledge received
address. 100
0010 0 1 X Lost arbitration while attempting a
repeated START. Abort failed transfer. 0 0 X
Reschedule failed transfer. 1 0 X
0001
11X
Lost arbitration while attempting a
STOP. No action required (transfer
complete/aborted). 000
00X
A STOP was detected while
addressed as a Slave T ransmitter
or Slave Receiver. Clear STO. 0 0 X
01X
Lost arbitration du e to a detected
STOP. Abort transfer. 0 0 X
Reschedule failed transfer. 1 0 X
0000 10X
A slave byte was received; ACK
requested.
Acknowledge received byte;
Read SMB0DAT. 001
Do not acknowledge
received byte. 000
11X
Lost arbitration while transmitting
a data byte as master. Abort failed transfer. 000
Reschedule failed transfer. 100
Table 21.4. SMBus Status Decoding (Continued)
Mode
Values Read
Current SMbus State Typical Response Options
Values
Written
Status
Vector
ACKRQ
ARBLOST
ACK
STA
STO
ACK
C8051F410/1/2/3
Rev. 1.1 207
22. 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 st andar d ba ud rates ( det ails
in Section “22.1. Enhanced Baud Rate Generation” on page 208). Received data buffering allows
UART0 to start rece ption of a second incoming dat a byte before sof tware has finished reading the previous
data byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit regis ter. Reads of SBUF0 alway s acces s t he buffe red Receive register;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardwa re when the CPU vectors to th e interr upt service routine. They must be cleared manually
by softwar e, allowing software to dete rmine the cause of the UAR T0 interrupt ( transmit complete or re ceive
complete).
Figure 22.1. UART0 Block Diagram
UART Baud
Rate Generator
RI
SCON
RI
TI
RB8
TB8
REN
MCE
SMODE
Tx Control
Tx Clock Send
SBUF
(TX Shift)
Start
Data
Write to
SBUF
Crossbar
TX
Shift
Zero Detector
Tx IRQ
SET
QD
CLR
Stop Bit
TB8
SFR Bus
Serial
Port
Interrupt
TI
Port I/O
Rx Control
Start
Rx Clock
Load
SBUF
Shift 0x1FF RB8
Rx IRQ
Input Shift Register
(9 bits)
Load SBUF
Read
SBUF
SFR Bus
Crossbar
RX
SBUF
(RX Latch)
C8051F410/1/2/3
208 Rev. 1.1
22.1. 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 22.2), 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.
Figure 22.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “24.1.3. Mode 2: 8-bit
Counter/Timer with Auto-Reload” on page 233). 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 six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the exter nal os cillator clock / 8, or
an external input T1. The UART0 baud rate is determined by Equation 22.1-A and Equation 22.1-B.
Equation 22.1. UART0 Baud Rate
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (8-bit
auto-reload mode reload value). T imer 1 clock frequency is selected as descri bed in Section “24. Timers”
on page 231. A quick reference for typical baud rates and system clock frequencies is given in Table 22.1
through Table 22.6. Note that the internal oscillator may still generate the system clock when the external
oscillator is driving Timer 1.
RX Timer
Start
Detected
Overflow
Overflow
TH1
TL1
TX Clock
2
RX Cl ock
2
Timer 1 UART
UartBaudRate 1
2
---T1_Overflow_Rate×=
T1_Overflow_Rate T1CLK
256 TH1–
--------------------------
=
A)
B)
C8051F410/1/2/3
Rev. 1.1 209
22.2. 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 below.
Figure 22.3. UART Interconnect Diagram
22.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one st art bit, ei ght data bit s (LSB first), a nd one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eig ht data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins wh en software writes a data byte to the SBUF0 register. The TI0 Transmit Inter-
rupt Flag ( SCON0.1) is set at th e end of the transm ission (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 condition s ar e me t, 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.
Figure 22.4. 8-Bit UART Timing Diagram
OR
RS-232
C8051Fxxx
RS-232
LEVEL
XLTR
TX
RX
C8051Fxxx
RX
TX
MCU
RX
TX
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE
C8051F410/1/2/3
210 Rev. 1.1
22.2.2. 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 so f twa re. It can be assigned the value of the p ar ity 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 ca n begin any time after the REN0 Receive Enable bit (SC ON0.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF0 rece ive re giste r if the followin g cond itions ar e me t:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when M CE0 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’.
Figure 22.5. 9-Bit UART Timing Diagram
22.3. 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 dat a bit. When a master proce ssor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte diff ers from a data byte
in that its ninth bit is logic 1; in a data byte, the nint h bit is alwa ys se t to logi c 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UAR T will generate an inter rupt only if the ninth bit is lo gic 1 (RB8 0 = 1) signifying a n address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmis-
sions until it receives the next address byte.
Multiple addresses ca n be assigned to a single sl ave 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).
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE D8
C8051F410/1/2/3
Rev. 1.1 211
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram
Master
Device Slave
Device
TXRX RX TX
Slave
Device
RX TX
Slave
Device
RX TX
V+
C8051F410/1/2/3
212 Rev. 1.1
SFR Definition 22.1. SCON0: Serial Port 0 Control
Bit7: S0MODE: Serial Por t 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: 8-bit UART with Variable Baud Rate.
1: 9-bit UART with Variable Baud Rate.
Bit6: UNUSED. Read = 1b. Write = don’t care.
Bit5: MCE0: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
S0MODE = 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
S0MODE = 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
Bit4: REN0: Receive Enable.
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3: TB80: Ninth Transm iss ion 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.
Bit2: 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.
Bit1: TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8-
bit UAR T Mode, or at the beginning o f the STOP bit in 9-bit UART Mod e). When the UAR T0
interrupt is enable d, setting this bit causes the CPU to vector to the UAR T0 interrupt service
routine. This bit must be cleared manually by software.
Bit0: RI0: Receive Interrupt Flag.
Set to ‘1’ by hardware wh en a byte of data ha s been received by UAR T0 (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.
R/W R R/W R/W R/W R/W R/W R/W Reset Value
S0MODE - MCE0 REN0 TB80 RB80 TI0 RI0 01000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0x98
C8051F410/1/2/3
Rev. 1.1 213
SFR Definition 22.2. SBUF0: Serial (UART0) Port Data Buffer
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 initiates the transmission. A read of SBUF0 returns the con-
tents of the receive latch.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x99
C8051F410/1/2/3
214 Rev. 1.1
Table 22.1. Timer Settings for S tandard Baud Rates
Using the Internal Oscillator
Frequency: 24.5 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Value (hex)
SYSCLK from
Internal Osc.
230400 -0.32% 106 SYSCLK XX 1 0xCB
115200 -0.32% 212 SYSCLK XX 1 0x96
57600 0.15% 426 SYSCLK XX 1 0x2B
28800 -0.32% 848 SYSCLK / 4 01 0 0x96
14400 0.15% 1704 SYSCLK / 12 00 0 0xB9
9600 -0.32% 2544 SYSCLK / 12 00 0 0x96
2400 -0.32% 10176 SYSCLK / 48 10 0 0x96
1200 0.15% 20448 SYSCLK / 48 10 0 0x2B
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitio ns can be found in Section 24.1.
Table 22.2. Timer Settings for S tandard Baud Rates
Using an External 25.0 MHz Oscillator
Frequency: 25.0 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Value (hex)
SYSCLK from
External Osc.
230400 -0.47% 108 SYSCLK XX 1 0xCA
115200 0.45% 218 SYSCLK XX 1 0x93
57600 -0.01% 434 SYSCLK XX 1 0x27
28800 0.45% 872 SYSCLK / 4 01 0 0x93
14400 -0.01% 1 736 SYSCLK / 4 01 0 0x27
9600 0.15% 2608 EXTCLK / 8 11 0 0x5D
2400 0.45% 10464 SYSCLK / 48 10 0 0x93
1200 -0.01% 20832 SYSCLK / 48 10 0 0x27
SYSCLK from
Internal Osc.
57600 -0.47% 432 EXTCLK / 8 11 0 0xE5
28800 -0.47% 864 EXTCLK / 8 11 0 0xCA
14400 0.45% 1744 EXTCLK / 8 11 0 0x93
9600 0.15% 2608 EXTCLK / 8 11 0 0x5D
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitio ns can be found in Section 24.1.
C8051F410/1/2/3
Rev. 1.1 215
Table 22.3. Timer Settings for S tandard Baud Rates
Using an External 22.1184 MHz Oscillator
Frequency: 22.1184 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Value (hex)
SYSCLK from
External Osc.
230400 0.00% 96 SYSCLK XX 1 0xD0
115200 0.00% 192 SYSCLK XX 1 0xA0
57600 0.00% 384 SYSCLK XX 1 0x40
28800 0.00% 768 SYSCLK / 12 00 0 0xE0
14400 0.00% 1536 SYSCLK / 12 00 0 0xC0
9600 0.00% 2304 SYSCLK / 12 00 0 0xA0
2400 0.00% 9216 SYSCLK / 48 10 0 0xA0
1200 0.00% 18432 SYSCLK / 48 10 0 0x40
SYSCLK from
Internal Osc.
230400 0.00% 96 EXTCLK / 8 11 0 0xFA
115200 0.00% 192 EXTCLK / 8 11 0 0xF4
57600 0.00% 384 EXTCLK / 8 11 0 0xE8
28800 0.00% 768 EXTCLK / 8 11 0 0xD0
14400 0.00% 1536 EXTCLK / 8 11 0 0xA0
9600 0.00% 2304 EXTCLK / 8 11 0 0x70
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1.
Table 22.4. Timer Settings for S tandard Baud Rates
Using an External 18.432 MHz Oscillator
Frequency: 18.432 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Value (hex)
SYSCLK from
External Osc.
230400 0.00% 80 SYSCLK XX 1 0xD8
115200 0.00% 160 SYSCLK XX 1 0xB0
57600 0.00% 320 SYSCLK XX 1 0x60
28800 0.00% 640 SYSCLK / 4 01 0 0xB0
14400 0.00% 1280 SYSCLK / 4 01 0 0x60
9600 0.00% 1920 SYSCLK / 12 00 0 0xB0
2400 0.00% 7680 SYSCLK / 48 10 0 0xB0
1200 0.00% 15360 SYSCLK / 48 10 0 0x60
SYSCLK from
Internal Osc.
230400 0.00% 80 EXTCLK / 8 11 0 0xFB
115200 0.00% 160 EXTCLK / 8 11 0 0xF6
57600 0.00% 320 EXTCLK / 8 11 0 0xEC
28800 0.00% 640 EXTCLK / 8 11 0 0xD8
14400 0.00% 1280 EXTCLK / 8 11 0 0xB0
9600 0.00% 1920 EXTCLK / 8 11 0 0x88
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1.
C8051F410/1/2/3
216 Rev. 1.1
Table 22.5. Timer Settings for S tandard Baud Rates
Using an External 11.0592 MHz Oscillator
Frequency: 11.0592 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Valu e (h ex )
SYSCLK from
External Osc.
230400 0.00% 48 SYSCLK XX 1 0xE8
115200 0.00% 96 SYSCLK XX 1 0xD0
57600 0.00% 192 SYSCLK XX 1 0xA0
28800 0.00% 384 SYSCLK XX 1 0x40
14400 0.00% 76 8 SYSCLK / 12 00 0 0xE0
9600 0.00% 1152 SYSCLK / 12 00 0 0xD0
2400 0.00% 4608 SYSCLK / 12 00 0 0x40
1200 0.00% 9216 SYSCLK / 48 10 0 0xA0
SYSCLK from
Internal Osc.
230400 0.00% 48 EXTCLK / 8 11 0 0xFD
115200 0.00% 96 EXTCLK / 8 11 0 0xFA
57600 0.00% 192 EXTCLK / 8 11 0 0xF4
28800 0.00% 384 EXTCLK / 8 11 0 0xE8
14400 0.00% 768 EXTCLK / 8 11 0 0xD0
9600 0.00% 1152 EXTCLK / 8 11 0 0xB8
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1.
Table 22.6. Timer Settings for S tandard Baud Rates
Using an External 3.6864 MHz Oscillator
Frequency: 3.6864 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error
Oscilla-
tor Divide
Factor
Timer Clock
Source
SCA1-SCA0
(pre-scale
select)* T1M* Timer 1
Reload
Value (hex)
SYSCLK from
External Osc.
230400 0.00% 16 SYSCLK XX 1 0xF8
115200 0.00% 32 SYSCLK XX 1 0xF0
57600 0.00% 64 SYSCLK XX 1 0xE0
28800 0.00% 128 SYSCLK XX 1 0xC0
14400 0.00% 256 SYSCLK XX 1 0x80
9600 0.00% 384 SYSCLK XX 1 0x40
2400 0.00% 1536 SYSCLK / 12 00 0 0xC0
1200 0.00% 3072 SYSCLK / 12 00 0 0x80
SYSCLK from
Internal Osc.
230400 0.00% 16 EXTCLK / 8 11 0 0xFF
115200 0.00% 32 EXTCLK / 8 11 0 0xFE
57600 0.00% 64 EXTCLK / 8 11 0 0xFC
28800 0.00% 128 EXTCLK / 8 11 0 0xF8
14400 0.00% 256 EXTCLK / 8 11 0 0xF0
9600 0.00% 384 EXTCLK / 8 11 0 0xE8
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1.
C8051F410/1/2/3
Rev. 1.1 217
23. Enhanced Serial Peripheral Interface (SPI0)
The Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus.
SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple mas-
ters and slaves on a sing le SPI b us . T he slav e-select (NSS) signal can be configured as an input to select
SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding conten-
tion on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be
configured as a chip -select output in master m ode, or disabled for 3-wire operation. Additional general pur-
pose port I/O pins can be used to select multiple slave devices in master mode.
Figure 23.1. SPI Block Diagram
SFR Bus
Data Path
Control
SFR Bus
Write
SPI0DAT
Receive Data Buffer
SPI0DAT
01234567
Shift Register
SPI CONTROL LOGIC
SPI0CKR
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CFG SPI0CN
Pin Interface
Control
Pin
Control
Logic
C
R
O
S
S
B
A
R
Port I/O
Read
SPI0DAT
SPI IRQ
Tx Data
Rx Data
SCK
MOSI
MISO
NSS
Transmit Data Buffer
Clock Divide
Logic
SYSCLK
CKPHA
CKPOL
SLVSEL
NSSMD1
NSSMD0
SPIBSY
MSTEN
NSSIN
SRMT
RXBMT
SPIF
WCOL
MODF
RXOVRN
TXBMT
SPIEN
C8051F410/1/2/3
218 Rev. 1.1
23.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
23.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input t o slave d evices . It
is used to serially trans fer data from the ma ster to th e slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
23.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impeda nce sta te when the SPI module is disa bled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
23.1.3. Serial Clock (SCK)
The serial cl ock (SCK) signal is an outp ut from the ma ster device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
23.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This
is intended for point-to-point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be used on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when operating SPI0 as a master device.
See Figure 23.2, Figure 23.3, and Figure 23.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bit s affect s the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS p in will not b e mapp ed by the cro ssbar. In all other mode s, the NSS signal will
be mapped to a pin on the device. See Section “18. Port Input/Output” on page 147 for general purpose
port I/O and crossbar information.
C8051F410/1/2/3
Rev. 1.1 219
23.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buf fer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift registe r, an d a data transf er begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers data to the SPI master on the MISO line in a full-duplex operation. Therefore, the
SPIF flag serves as both a transmit -complete and re ceive-data-ready flag. The d at a by te rece ived from the
slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it
is moved to the receive buffer where it can be read by the processor by reading SPI0DAT.
When configured as a master, SPI0 can opera te in one of three d iffer ent modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-m aster m ode is act ive when NS S-
MD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is
used to disable the ma ster SPI0 when anothe r master is accessing the bus. When NSS is pulled low in this
mode, MSTEN (SPI0CFG.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a
Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re -enab led in software under these ci rcumst ances. In multi-master systems, devices will
typically default to being sla ve devices while th ey are not acting as the system ma ster device. In multi-mas -
ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 23.2 shows a connection diagram between two master devices in multiple-mas te r mo de .
3-wire single-m aster mod e is active wh en NSSMD1 (S PI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 23.3
shows a connection diagram between a master device in 3-wire master mode an d a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using gene ral-p urpose I/O pins. Figure 23.4 shows a connection diagra m for a master device i n
4-wire master mode and two slave devices.
C8051F410/1/2/3
220 Rev. 1.1
Figure 23.2. Multiple-Master Mode Connection Diagram
Figure 23.3. 3-Wire Single Master and Slave Mode Connection Diagram
Figure 23.4. 4-Wire Single Master and Slave Mode Connection Diagram
23.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig-
nal. A bit counte r in the SPI0 lo gic counts SCK edges. When 8 bits have been shifted into the shift r egiste r,
the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive
buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master
device is pre- loaded into the shift registe r by writing to SPI0DAT. Writes to SPI0DAT are double-buffered,
and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer
will immediately be transferred into the shift register. When the shift register already contains data, the SPI
will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or current)
SPI transfer.
Master
Device 2
Master
Device 1
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS
GPIO NSS
GPIO
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS NSS
GPIO
Slave
Device
MOSI
MISO
SCK
NSS
C8051F410/1/2/3
Rev. 1.1 221
The shift register contents are locked after the slave detects the first edge of SCK. Writes to SPI0DAT that
occur after the first SCK edge will be held in the TX latch until the end of the current transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is lo gic 1. The bit counter is r eset on a falling ed ge of NSS. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 23.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is not a way
of uniquely addressing the device in 3-wire slave mode, SPI0 must be the on ly slave device present on th e
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and re-
enabling SPI0 with the SPIEN bit. Figure 23.3 shows a connection diagram between a slave device in 3-
wire slave mod e and a ma ster device.
23.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following interrupt bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag , WCOL (SPI0CN.6) is se t to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the tr ansmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master
in multi-master mode and the NSS pin is pu lled low. When a Mo de Fault occurs, the M STEN
and SPIEN bits are set to logic 0 to disable SPI0 and allow another master device to access
the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed while the receive buffer still holds an unread byte from a previous
transfer. The new byt e is not tr an sf er re d to th e r ece ive bu ffer, allo win g th e p rev io us ly re ce ived
data byte to be read. The data byte which caused the overrun is lost.
23.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between a r ising ed ge or a falling edg e.
Both master and slave devices must be configured to use the same clock phase and polarity. SPI0 should
be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The clock
and data line relationships are shown in Figure 23.5.
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 23.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum dat a transfer rate (bit s/sec) is one-half the system clock frequency or 12.5 MHz,
C8051F410/1/2/3
222 Rev. 1.1
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-
wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does no t need to receive data from the slave (i.e. half-duplex operation) , the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the seri al inpu t data synchronously with the slave’s
system clock.
Figure 23.5. Data/Clock Timing Relationship
23.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
SCK
(CKPO L=0, CKPHA=0)
SCK
(CKPO L=0, CKPHA=1)
SCK
(CKPO L=1, CKPHA=0)
SCK
(CKPO L=1, CKPHA=1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO/MOSI
C8051F410/1/2/3
Rev. 1.1 223
SFR Definition 23.1. SPI0CFG: SPI0 Configuration
Bit 7: SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or Slave Mode).
Bit 6: MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
Bit 5: CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK period.*
Bit 4: CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Bit 3: SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
Bit 2: NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at the time that
the register is read. This input is not de-glitched.
Bit 1: SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shif t register,
and there is no new information available to read from the transmit buf fer or write to the
receive buffer. It returns to logic 0 when a dat a byte is transfe rred to the shift register from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
Bit 0: RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information availa ble in the receive buf fer that ha s not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note: See Table 23.1 for timing parameters.
R R/W R/W R/W R R R R Reset Value
SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT 00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA1
C8051F410/1/2/3
224 Rev. 1.1
SFR Definition 23.2. SPI0CN: SPI0 Control
Bit 7: SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 6: WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware if a wr ite to SPI0DAT is attempted when the transmit
buffer has not been emptied to the SPI shift register. It must be cleared by sof tware.
Bit 5: MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not auto-
matically cleared by hardware. It must be cleared by software.
Bit 4: RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buf-
fer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not auto m at ically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “23.2. SPI0 Master Mode Operation” on p age 219 and Section “23.3. SPI0
Slave Mode Operation” on page 220).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mappe d as an outp ut from the device and will
assume the value of NSSMD0.
Bit 1: TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the tr an smit b uffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
Bit 0: SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
R/W R/W R/W R/W R/W R/W R R/W Reset Value
SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN 00000110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xF8
C8051F410/1/2/3
Rev. 1.1 225
SFR Definition 23.3. SPI0CKR: SPI0 Clock Rate
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determin e the fr equency o f the SCK outpu t when the SPI0 mod ule is config ured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following eq uation , where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA2
fSCK 2000000
241+()×
--------------------------
=
fSCK 200kHz=
fSCK SYSCLK
2SPI0CKR 1+()×
-------------------------------------------------
=
C8051F410/1/2/3
226 Rev. 1.1
SFR Definition 23.4. SPI0DAT: SPI0 Data
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA3
C8051F410/1/2/3
Rev. 1.1 227
Figure 23.6. SPI Master Timing (CKPHA = 0)
Figure 23.7. SPI Master Timing (CKPHA = 1)
SCK*
T
MCKH
T
MCKL
MOSI
T
MIS
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIH
SCK*
T
MCKH
T
MCKL
MISO
T
MIH
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIS
C8051F410/1/2/3
228 Rev. 1.1
Figure 23.8. SPI Slave Timing (CKPHA = 0)
Figure 23.9. SPI Slave Timing (CKPHA = 1)
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SEZ
T
SDZ
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SEZ
T
SDZ
C8051F410/1/2/3
Rev. 1.1 229
Table 23.1. SPI Slave Timing Parameters
Parameter Description Min Max Units
Master Mode Ti ming* (See Figure 23.6 and Figure 23.7)
TMCKH SCK High Time 1 x TSYSCLK —ns
TMCKL SCK Low Time 1 x TSYSCLK —ns
TMIS MISO Valid to SCK Sample Edge 20 —ns
TMIH SCK Sample Edge to MISO Change 0 — ns
Slave Mode Ti ming* (See Figure 23.8 and Figure 23.9)
TSE NSS Falling to First SCK Edge 2 x TSYSCLK —ns
TSD Last SCK Edge to NSS Rising 2 x TSYSCLK —ns
TSEZ NSS Falling to MISO Valid —4 x TSYSCLK ns
TSDZ NSS Rising to MISO High-Z —4 x TSYSCLK ns
TCKH SCK High Time 5 x TSYSCLK —ns
TCKL SCK Low Time 5 x TSYSCLK —ns
TSIS MOSI Valid to SCK Sample Edge 2 x TSYSCLK —ns
TSIH SCK Sample Edge to MOSI Change 2 x TSYSCLK —ns
TSOH SCK Shift Edge to MISO Change —4 x TSYSCLK ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK) in ns.
C8051F410/1/2/3
230 Rev. 1.1
NOTES:
C8051F410/1/2/3
Rev. 1.1 231
24. Timers
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and two are 16-bit auto-reload timer for use with other device peripherals 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 oper-
ation. Timer 2 and Timer 3 offer 16-bit and split 8-bit timer functionality with auto-reload. Timer 2 and
Timer 3 also have a smaRTClock Capture Mode that can be used to measure the smaRTClock clock with
respect to anot he r oscillator.
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 24.3 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 and
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
clock source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incr emented on each hi gh-to-low transition at the selected input pin (T0 o r T1). Event s with a fre-
quency of up to one-fourth the system clock's freq uency can be counte d. The input signal need n ot be peri-
odic, but it must be held at a given level for at least two full system clock cycles to ensure the level is
properly sampled.
24.1. Timer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1)
and a high b yte (TH0 or TH1) . The Counter /Timer Control register (TCON) is used to enable Timer 0 and
T imer 1 as well a s indicate status. Timer 0 interrupts can be ena bled by setting the ET0 bit in the IE register
(Section “12.4. Interrupt Register Descriptions” on page 112); Timer 1 interrupts can be enabled by
setting the ET1 bit in the IE register (Section 12.4). 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.
24.1.1. 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 descr ibed 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.
Timer 0 and Timer 1 Modes: Timer 2 Modes: Timer 3 Modes:
13-bit counter/timer 16-bit timer with auto-reload 16-bit timer with auto-reload
16-bit counter/timer
8-bit counter/timer with auto-reloa d Two 8-bit timers with auto- reload T wo 8-bit timers with a uto-reload
Two 8-bit counter/timers
(Timer 0 only)
C8051F410/1/2/3
232 Rev. 1.1
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 (Refer to Section
“18.1. Priority Crossbar Decoder” on page 149 for information on sele ctin g 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 system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock
Scale bits in CKCON (see SFR Definition 24.3).
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 d efined by bit IN0PL in register IT01CF (see SFR Definition 12.7. “IT01CF: INT0/INT1
Configuration” on page 118). Setting GATE0 to ‘1’ allows the timer to be controlled by the external input
signal /INT0 (see Section “12.4. Interrupt Register Descriptions” on page 112), facilitating pulse width
measurements.
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 fo rm the 13-bit registe r fo r Timer 1 in the same manne r as d escribe d above for TL0 a nd 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 12.7. “IT01CF: INT0/INT1 Configuration” on page 118).
Figure 24.1. T0 Mode 0 Block Diagram
TR0 GATE0 /INT0 Counter/Timer
0 X X Disabled
1 0 X Enabled
110Disabled
111Enabled
X = Don't Care
IT01CF
C8051F410/1/2/3
Rev. 1.1 233
24.1.2. 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 ma nner as for Mode 0.
24.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configur es Timer 0 and Timer 1 to ope rate as 8- bit counter/timers with automatic reload of the st art
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 th e timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0
is active as defined by bit IN0PL in r egister IT01CF (see Section “12.5. External Interrupts” on p age 117
for details on the external input signals /INT0 and /INT1).
Figure 24.2. T0 Mode 2 Block Diagram
IT01CF
C8051F410/1/2/3
234 Rev. 1.1
24.1.4. 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 ca n use either the system clock or an external input signal as it s 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 set s the Timer 1 overflow flag TF1 on overflow a nd thus con trols
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 ov er flow can be us ed t o gene r ate ba ud rates for the SMBus and U ART. While Timer 0 is oper-
ating in Mode 3, Timer 1 run control is handled through its mode settings. To run T imer 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.
Figure 24.3. T0 Mode 3 Block Diagram
TL0
(8 bits)
TMOD
0
1
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
Interrupt
0
1
SYSCLK
Pre-scaled Clock TR1 TH0
(8 bits)
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TR0
GATE0
IN0PL
XOR
/INT0
T0
Crossbar
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
Rev. 1.1 235
SFR Definition 24.1. TCON: Timer Control
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 Tim er 1 inte rr u pt se rvic e ro utine.
0: No Timer 1 over flo w det ec te d.
1: Timer 1 has overflowed.
Bit6: TR1: Timer 1 Run Control.
0: Timer 1 disab l ed .
1: Timer 1 enabled.
Bit5: 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 Tim er 0 inte rr u pt se rvic e ro utine.
0: No Timer 0 over flo w det ec te d.
1: Timer 0 has overflowed.
Bit4: TR0: Timer 0 Run Control.
0: Timer 0 disab l ed .
1: Timer 0 enabled.
Bit3: IE1: External Interrupt 1.
This flag is set by hardware when an edge /level of type defined by IT1 is de tected. It can be
cleared by soft ware but is automatica lly cleared when the CPU vectors to the Exter nal 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 12.7. “IT01CF: INT0/INT1 Con-
figuration” on page 118).
Bit2: IT1: Interrupt 1 Type Select.
This bit selects whether the configured /INT1 interrupt will be edge or level sensitive. /INT1
is configured active low or high by the IN1PL bit in the IT01CF register (see SFR
Definition 12.7. “IT01CF: INT0/INT1 Configuration” on page 118).
0: /INT1 is level triggered.
1: /INT1 is edge triggere d.
Bit1: IE0: External Interrupt 0.
This flag is set by hardware when an edge /level of type defined by IT0 is de tected. It can be
cleared by soft ware but is automatica lly cleared when the CPU vectors to the Exter nal 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 12.7. “IT01CF: INT0/INT1 Con-
figuration” on page 118).
Bit0: 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 IT0 1CF (see SFR
Definition 12.7. “IT01CF: INT0/INT1 Configuration” on page 118).
0: /INT0 is level triggered.
1: /INT0 is edge triggere d.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0x88
C8051F410/1/2/3
236 Rev. 1.1
SFR Definition 24.2. TMOD: Timer Mode
Bit7: GATE1: Timer 1 Gate Control.
0: Timer 1 enable d wh en TR1 = 1 irrespe ctive of /INT1 logic level.
1: Timer 1 enable d on ly whe n TR1 = 1 AND /INT1 is active as defined by bit IN1PL in regis-
ter IT01CF (see SFR Definition 12.7. “IT01CF: INT0/INT1 Configuration” on page 118).
Bit6: C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
Bit3: GATE0: Timer 0 Gate Control.
0: Timer 0 enable d wh en TR0 = 1 irrespe ctive of /INT0 logic level.
1: Timer 0 enable d on ly whe n TR0 = 1 AND /INT0 is active as defined by bit IN0PL in regis-
ter IT01CF (see SFR Definition 12.7. “IT01CF: INT0/INT1 Configuration” on page 118).
Bit2: C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
GATE1 C/T1 T1M1 T1M0 GATE0 C/T0 T0M1 T0M0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x89
T1M1 T1M0 Mode
0 0 Mode 0: 13-bit counter/timer
0 1 Mode 1: 16-bit counter/timer
1 0 Mode 2: 8-bit counter/timer with auto -reload
1 1 Mode 3: Timer 1 inactive
T0M1 T0M0 Mode
0 0 Mod e 0: 13- bit co un te r/ tim er
0 1 Mod e 1: 16- bit co un te r/ tim er
1 0 Mode 2: 8-bit counter/timer with auto-reload
1 1 Mode 3: Two 8-bit counter/timers
C8051F410/1/2/3
Rev. 1.1 237
SFR Definition 24.3. CKCON: Clock Control
Bit7: T3MH: Timer 3 High Byte Clock Select.
This bit selects the clock supplied to the Ti mer 3 high byte if Timer 3 is configured in split 8-
bit timer mode. T3MH is ignored if Timer 3 is in any other mode.
0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: T imer 3 high byte uses the system clock.
Bit6: T3ML: Timer 3 Low Byte Clock Selec t.
This bit selects the clock supplied to Timer 3. If Timer 3 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: T imer 3 low byte uses the system clock.
Bit5: T2MH: Timer 2 High Byte Clock Select.
This bit selects the clock supplied to the Ti mer 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: T imer 2 high byte uses the system clock.
Bit4: T2ML: Timer 2 Low Byte Clock Selec t.
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: T imer 2 low byte uses the system clock.
Bit3: T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logi c 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Timer 1 uses the system clock.
Bit2: 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.
Bits1–0: SCA1–SCA0: T i mer 0/1 Prescale Bits.
These bits control the division of the clock supplied to Timer 0 and Timer 1 if configured to
use prescaled clock inputs.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
T3MH T3ML T2MH T2ML T1M T0M SCA1 SCA0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8E
SCA1 SCA0 Prescaled Clock
0 0 System clock divided by 12
0 1 System clock divided by 4
1 0 System clock divided by 48
1 1 External clock divided by 8
Note: External clock divided by 8 is synchronized with
the system clock.
C8051F410/1/2/3
238 Rev. 1.1
SFR Definition 24.4. TL0: Timer 0 Low Byte
SFR Definition 24.5. TL1: Timer 1 Low Byte
SFR Definition 24.6. TH0: Timer 0 High Byte
SFR Definition 24.7. TH1: Timer 1 High Byte
Bits 7–0 : TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8A
Bits 7–0 : TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8B
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8C
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x8D
C8051F410/1/2/3
Rev. 1.1 239
24.2. Timer 2
T imer 2 is a 16-bit time r 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 T2 SPLIT bit (TMR2CN.3) defines
the T imer 2 operation mod e. T i mer 2 can also be used in Capture Mode to measure the smaR TClock clock
frequency or the External Oscillator clock frequency.
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 oscillator source divided by 8 is synchronized with the system clock.
24.2.1. 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 24.4,
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 fro m 0xFF to 0x00.
Figure 24.4. Timer 2 16-Bit Mode Block Diagram
External Clock / 8
SYSCLK / 12
SYSCLK
TMR2L TMR2H
TMR2RLL TMR2RLH
Reload
TCLK
0
1
TR2
TMR2CN
T2SPLIT
TF2L
TF2H
T2XCLK
TR2
0
1
T2XCLK
Interrupt
TF2LEN
TMR2L
Overflow
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
240 Rev. 1.1
24.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT is s et, Timer 2 oper ates as two 8-bi t timers (TMR2H and TMR2L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 24.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH
holds the reload value fo r TMR2 H. The TR 2 bit in TMR2CN hand les the run cont rol for TMR2H. T MR2 L is
always runni ng when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the extern al 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:
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 overflo ws. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an in te rrup t is g ene r-
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.
Figure 24.5. Timer 2 8-Bit Mode Block Diagram
T2MH T2XCLK TMR2H Clock Source T2ML T2XCLK TMR2L Clock Source
0 0 SYSCLK / 12 0 0 SYSCLK / 12
0 1 External Clock / 8 0 1 External Clock / 8
1 X SYSCLK 1 X SYSCLK
SYSCLK
TCLK
0
1TR2
External Clock / 8
SYSCLK / 12 0
1
T2XCLK
1
0
TMR2H
TMR2RLH Reload
Reload
TCLK TMR2L
TMR2RLL
Interrupt
TMR2CN
T2SPLIT
TF2LEN
TF2L
TF2H
T2XCLK
TR2
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
Rev. 1.1 241
24.2.3. External/smaRTClock Capture Mode
Capture Mode allows either the external oscillator or the smaRTClock clock to be measured against the
system clock. The external oscillator and smaRTClock clock can also be compared against each other.
Timer 2 can be clocked from the system clock, the system clock divided by 12, the external oscillator
divided by 8, or the smaRTClock clock divided by 8, depending on the T2ML (CKCON.4), T2XCLK, and
T2RCLK settings. The timer will capture either every 8 external clock cycles or every 8 s maRTClock clock
cycles, depending on the T2RCLK setting. When a capture event is generated, the contents of Timer 2
(TMR2H:TMR2L) are loaded into th e Timer 2 reload registers (TMR2RLH:TMR2RLL) and the TF2H flag is
set. By recording the difference between two successive timer capture values, the external oscillator or
smaRTClock clock can be determined with respect to the Timer 2 clock. The Timer 2 clock should be much
faster than the capture clock to a chieve an accurate read ing . Timer 2 should be in 16-b it au to-r eloa d mod e
when using Capt ur e Mo d e.
For example, if T2ML = 1b, T2RCLK = 0b, and TF2CEN = 1b, Timer 2 will clock every SYSCLK and cap-
ture every smaRTClock clock divided by 8. If the SYSCLK is 24.5 MHz and the difference between two
successive captures is 5984, then the smaRTClock clock is:
24.5 MHz / (5984 / 8) = 0.032754 MHz or 32.754 kHz.
This mode allows software to determine the exact smaRTClock frequency in self-oscillate mode and the
external oscillator frequency when an RC network or capacitor is used to generate the signal.
Figure 24.6. Timer 2 Capture Mode Block Diagram
TCLK
0
1
TR2 TMR2H
TMR2RLH
TF2CEN
TMR2L
TMR2RLL
Interrupt
TMR2CN
T2RCLK
TF2CEN
TF2LEN
TF2L
TF2H
T2XCLK
TR2
sm a RTC lo ck / 8
Exte r n a l Osc . / 8
0
1
T2RCLK
0
1
T2XCLK
SYSCLK
smaRTC lock / 8
Exte rn a l Osc . / 8 0
1
T2RCLK
SYSCLK / 12 Capture
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
242 Rev. 1.1
SFR Definition 24.8. TMR2CN: Timer 2 Control
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 T imer 2 overflows fr om 0xFFFF to 0x0000. When the T ime r 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.
Bit6: 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 T ime r 2 interrupt s are enabled. TF2L
will set when the low byte overflo ws regardless of the Timer 2 mode. This bit is not automat-
ically cleared by hardware.
Bit5: TF2LEN: Timer 2 Low Byte Interrupt Enable.
This bit enables/dis abl es 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 inte rr up ts disabl ed .
1: Timer 2 Low Byte inte rr up ts enable d.
Bit4: TF2CEN. Timer 2 Capture Enable.
0: Timer 2 capt ur e mo d e disa b l ed .
1: Timer 2 capt ur e mode enable d.
Bit3: 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 disab l ed .
1: Timer 2 ena ble d.
Bit1: T2RCLK: Timer 2 Capture Mode.
This bit controls the Timer 2 capture source when TF2CEN=1. If T2XCLK = 1 and T2ML
(CKCON.4) = 0, this bit also controls the clock source for Timer 2.
0: Capture every smaRTClock clock/8. If T2XCLK = 1 and T2ML (CKCON.4) = 0, count at
external oscillat or /8 .
1: Capture every external oscillator/8. If T2XCLK = 1 and T2ML (CKCON.4) = 0, count a t
smaRTClock clock/8.
Bit0: T2XCLK: Timer 2 Ex ternal 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 uses the clock defined by the T2RCLK bit.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF2H TF2L TF2LEN TF2CEN T2SPLIT TR2 T2RCLK T2XCLK 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xC8
C8051F410/1/2/3
Rev. 1.1 243
SFR Definition 24.9. TMR2RLL: Timer 2 Reload Register Low Byte
SFR Definition 24.10. TMR2RLH: Timer 2 Reload Register High Byte
SFR Definition 24.11. TMR2L: Timer 2 Low Byte
SFR Definition 24.12. TMR2H Timer 2 High Byte
Bits 7–0: TMR2RLL: Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCA
Bits 7–0: TMR2RLH: Timer 2 Reload Register High Byte.
The TMR2RLH holds the high byte of the reload value for Timer 2.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCB
Bits 7–0: TMR2L: Timer 2 Low Byte.
In 16-bit mode, the TMR2L register cont ains the low byte of the 16-bit T imer 2. In 8-bit mode,
TMR2L contains the 8-bit low byte timer value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCC
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.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCD
C8051F410/1/2/3
244 Rev. 1.1
24.3. Timer 3
T imer 3 is a 16-bit time r formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte ). Timer 3 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3 SPLIT bit (TMR3CN.3) defines
the T imer 3 operation mode . Timer 3 can also be used in Capture Mode to measure the smaR TClock clock
frequency or the External Oscillator clock frequency.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. Note that the external oscillator source divided by 8 is synchronized with the system
clock.
24.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3
reload registers (TMR3RLH and TM3RLL) is loaded into the Timer 3 register as shown in Figure 24.7, and
the Timer 3 H igh Byte O verflow Fla g (TMR3CN.7) is set. If Timer 3 interrupts are enabled, an interrupt will
be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and the TF3LEN bit
is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) overflow from 0xFF
to 0x00.
Figure 24.7. Timer 3 16-Bit Mode Block Diagram
External Clock / 8
SYSCLK / 12
SYSCLK
TMR3L TMR3H
TMR3RLL TMR3RLH Reload
TCLK
0
1
TR3
TMR3CN
T3SPLIT
TF3L
TF3H
T3XCLK
TR3
0
1
T3XCLK
Interrupt
TF3LEN
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
Rev. 1.1 245
24.3.2. 8-bit Timers with Auto-Reload
When T3SPLIT is s et, Timer 3 oper ates as two 8-bi t timers (TMR3H and TMR3L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 24.8. TMR3RLL holds the reload value for TMR3L; TMR3RLH
holds the reload value fo r TMR3 H. The TR 3 bit in TMR3CN hand les the run cont rol for TMR3H. T MR3 L is
always runni ng when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the extern al oscillator clock
source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or
the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows:
The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows
from 0xFF to 0x00. When Timer 3 interrupts ar e enabled, an interrupt is generate d each time TMR3H over-
flows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each
time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the TF3H and
TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not
cleared by hardware and must be manually cleared by software.
Figure 24.8. Timer 3 8-Bit Mode Block Diagram
T3MH T3XCLK TMR3H Clock Source T3ML T3XCLK TMR3L Clock Source
0 0 SYSCLK / 12 0 0 SYSCLK / 12
0 1 External Clock / 8 0 1 External Clock / 8
1 X SYSCLK 1 X SYSCLK
SYSCLK
TCLK
0
1TR3
External Clock / 8
SYSCLK / 12 0
1
T3XCLK
1
0
TMR3H
TMR3RLH Reload
Reload
TCLK TMR3L
TMR3RLL
Interrupt
TMR3CN
T3SPLIT
TF3CEN
TF3LEN
TF3L
TF3H
T3XCLK
TR3
To ADC
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
246 Rev. 1.1
24.3.3. External/smaRTClock Capture Mode
Capture Mode allows either the external oscillator or the smaRTClock clock to be measured against the
system clock. The external oscillator and smaRTClock clock can also be compared against each other.
Timer 3 can be clocked from the system clock, the system clock divided by 12, the external oscillator
divided by 8, or the smaRTClock clock divided by 8, depending on the T3ML (CKCON.6), T3XCLK, and
T3RCLK settings. The timer will capture either every 8 external clock cycles or every 8 s maRTClock clock
cycles, depending on the T3RCLK setting. When a capture event is generated, the contents of Timer 3
(TMR3H:TMR3L) are loaded into th e Timer 3 reload registers (TMR3RLH:TMR3RLL) and the TF3H flag is
set. By recording the difference between two successive timer capture values, the external oscillator or
smaRTClock clock can be determined with respect to the Timer 3 clock. The Timer 3 clock should be much
faster than the capture clock to a chieve an accurate read ing . Timer 3 should be in 16-b it au to-r eloa d mod e
when using Capt ur e Mo d e.
For example, if T3ML = 1b, T3RCLK = 0b, and TF3CEN = 1b, Timer 3 will clock every SYSCLK and cap-
ture every smaRTClock clock divided by 8. If the SYSCLK is 24.5 MHz and the difference between two
successive captures is 5984, then the smaRTClock clock is:
24.5 MHz / (5984 / 8) = 0.032754 MHz or 32.754 kHz.
This mode allows software to determine the exact smaRTClock frequency in self-oscillate mode and the
external oscillator frequency when an RC network or capacitor is used to generate the signal.
Figure 24.9. Timer 3 Capture Mode Block Diagram
TCLK
0
1
TR3 TMR3H
TMR3RLH
TF3CEN
TMR3L
TMR3RLL
Interrupt
TMR3CN
T3RCLK
TF3CEN
TF3LEN
TF3L
TF3H
T3XCLK
TR3
smaRTC lock / 8
Ext e rn al Osc . / 8
0
1
T3RCLK
0
1
T3XCLK
SYSCLK
smaRTC lock / 8
Exte rn a l Osc. / 8 0
1
T3RCLK
SYSCLK / 12 Capture
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F410/1/2/3
Rev. 1.1 247
SFR Definition 24.13. TMR3CN: Timer 3 Control
Bit7: TF3H: Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when T imer 3 overflows fr om 0xFFFF to 0x0000. When the T ime r 3 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine.
TF3H is not automatically cleared by hardware and must be cleared by software.
Bit6: TF3L: Timer 3 Low Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF3LEN is set and T ime r 3 interrupt s are enabled. TF3L
will set when the low byte overflo ws regardless of the Timer 3 mode. This bit is not automat-
ically cleared by hardware.
Bit5: TF3LEN: Timer 3 Low Byte Interrupt Enable.
This bit enables/dis abl es Timer 3 Low Byte interrupts. If TF3LEN is set and Timer 3 inter-
rupts are enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
This bit should be cleared when operating Timer 3 in 16-bit mode.
0: Timer 3 Low Byte inte rr up ts disabl ed .
1: Timer 3 Low Byte inte rr up ts enable d.
Bit4: TF3CEN: Timer 3 Capture Enable.
0: Timer 3 capt ur e mo d e disa b l ed .
1: Timer 3 capt ur e mode enable d.
Bit3: T3SPLIT: Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 operates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timers.
Bit2: TR3: Timer 3 Run Control.
This bit enables/disables Timer 3. In 8-bit mode, this bit enables/disables TMR3H only;
TMR3L is always enabled in this mode.
0: Timer 3 disab l ed .
1: Timer 3 ena ble d.
Bit1: T3RCLK: Timer 3 Capture Mode.
This bit controls the Timer 3 capture source when TF3CEN=1. If T3XCLK = 1 and T3ML
(CKCON.6) = 0, this bit also controls the clock source for Timer 3.
0: Capture every smaRTClock clock/8. If T3XCLK = 1 and T3ML (CKCON.6) = 0, count at
external oscillat or /8 .
1: Capture every external oscillator/8. If T3XCLK = 1 and T3ML (CKCON.6) = 0, count a t
smaRTClock clock/8.
Bit0: T3XCLK: Timer 3 Ex ternal Clock Select.
This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock
Select bits (T3MH and T3ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 3 external clock selection is the system clock divided by 12.
1: Timer 3 external clock uses the clock defined by the T3RCLK bit.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF3H TF3L TF3LEN TF3CEN T3SPLIT TR3 T3RCLK T3XCLK 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x91
C8051F410/1/2/3
248 Rev. 1.1
SFR Definition 24.14. TMR3RLL: Timer 3 Reload Register Low Byte
SFR Definition 24.15. TMR3RLH: Timer 3 Reload Register High Byte
SFR Definition 24.16. TMR3L: Timer 3 Low Byte
SFR Definition 24.17. TMR3H Timer 3 High Byte
Bits 7-0: TMR3RLL: Timer 3 Reload Register Low Byte.
TMR3RLL holds the low byte of the reload value for Timer 3.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x92
Bits 7-0: TMR3RLH: Timer 3 Reload Register High Byte.
The TMR3RLH holds the high byte of the reload value for Timer 3.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x93
Bits 7-0 : TMR3L: Timer 3 Low Byte.
In 16-bit mode, the TMR3L register cont ains the low byte of the 16-bit T imer 3. In 8-bit mode,
TMR3L contains the 8-bit low byte timer value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x94
Bits 7-0: TMR3H: Timer 3 High Byte.
In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In 8-bit
mode, TMR3H contains the 8-bit high byte timer value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x95
C8051F410/1/2/3
Rev. 1.1 249
25. Programmable Counter Array (PCA0)
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 six 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 “18.1. Priority
Crossbar Decoder” on page 149 for details on configuring the Crossbar). The counter/timer is driven by
a programmable timebase that can select between seven sources: system clock, system clock divided by
four, system clock divided by twelve, the external oscillator clock source divide d by 8, smaRTClock Clock
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, Soft-
ware Timer , High-Speed Output, Freq uency Output, 8-Bit PWM, or 16-Bit PWM (each mod e is described i n
Section “25.2. Capture/Compare Modules” on page 251). The PCA is configured and controlled
through the system controller's Special Function Registers. The PCA block diagram is shown in
Figure 25.1
Import ant Note: The PCA Module 5 may be used as a watchdog timer (WDT), and is enabled in this mode
following a syst em reset. Access to certain PCA registers is restricted while WDT mode is enabled.
See Section 25.3 for details.
Figure 25.1. PCA Block Diagram
Capture/Compare
Module 1
Capture/Compare
Module 0 Capture/Compare
Module 2 Capture/Compare
Module 3
CEX1
ECI
Crossbar
CEX2
CEX3
CEX0
Port I/O
16-Bit Counter/Timer
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
smaRTClock/8
Capture/Compar e
Module 4
CEX4
Capture/Compar e
Module 5
CEX5
C8051F410/1/2/3
250 Rev. 1.1
25.1. 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 Regist er first guaran tees an a ccurate read ing of t he entire 16-bit PCA0 counte r.
Reading PCA0H or PCA0L does not disturb the counte r operation. The CPS2-CPS0 bits in the PCA0MD
register select the timebase for the counter/timer as shown in Table 25.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft-
ware (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 interrupts
are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing t he CIDL bit
in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle mode.
Figure 25.2. PCA Counter/Timer Block Diagram
Table 25.1. PCA Timebase Input Options
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
0 1 1 High-to-low transitions on ECI (max rate = system clock divided by 4)
1 0 0 System clock
1 0 1 External oscillator source divided by 8*
1 1 0 smaRTClock clock divided by 8*
*Note: External clock divided by 8 and smaRTClock clock divided by 8 are synchronized with the system clock.
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
IDLE
0
1PCA0H PCA0L
Snapshot
Register
To SFR Bus
Overflow To PCA Interrupt System
CF
PCA0L
read
To PCA Mod ules
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
000
001
010
011
100
101
SYSCLK
Externa l C lock/8
RTC0 Clock/8 110
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F410/1/2/3
Rev. 1.1 251
25.2. 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 reg isters are used to e xchange dat a with a module and configu re the modu le's
mode of operation.
Table 25.2 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 25.3 for details on the PCA interrupt configura tion.
Figure 25.3. PCA Interrupt Block Diagram
Table 25.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT TOG PWM ECCF Operation Mode
X X 10000X
Capture triggered by positive edge on
CEXn
X X 01000X
Capture triggered by negative edge on
CEXn
X X 11000X
Capture triggered by transition on
CEXn
X 1 00100XSoftware Timer
X 1 0 0 1 1 0 X High Speed Output
X 1 0 0 X 1 1 X Freq ue n cy Ou tp ut
0 1 0 0 X 0 1 X 8-Bit Pulse Width Modulator
1 1 0 0 X 0 1 X 16-Bit Pulse Width Modula to r
X = Don’t Care
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
PCA0MD
C
I
D
L
E
C
F
C
P
S
1
C
P
S
0
C
P
S
2
0
1
PCA Module 0
(CCF0)
PCA Module 1
(CCF1)
ECCF1
0
1
ECCF0
0
1
PCA Module 2
(CCF2)
ECCF2
0
1
PCA Module 3
(CCF3)
ECCF3
ECCF4
PCA Counter/
Timer Overflow 0
1
Interru p t
Priority
Decoder
EPCA0
(EIE1.4)
PCA0CPMn
(for n = 0 to 5)
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
1
PCA Module 4
(CCF4)
0
1
PCA Module 5
(CCF5)
0
1
EA
(IE.7)
0
1
ECCF5
C8051F410/1/2/3
252 Rev. 1.1
25.2.1. 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 load it in to the corr esponding mo dule 's 1 6-bit ca pture/co mpare register (PCA0 CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn re giste r ar e u sed to sele ct the type o f tran si-
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.
Figure 25.4. PCA Capture Mode Diagram
Note: The CEXn input signal must remain high or low for at least 2 system clock cyc les to be recognized
by the hardware.
PCA0L
PCA0CPLn
PCA
Timebase
CEXn
CrossbarPort I/O
PCA0H
Capture
PCA0CPHn
0
1
0
1
(to CCFn)
PCA Interrupt
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F410/1/2/3
Rev. 1.1 253
25.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is comp are d to the mod ule' s 16- bit ca pture/ co mpare
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1 and an interr upt requ est is ge nerated if CCF inte rrupt s ar e enabled. Th e 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 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 25.5. PCA Software Timer Mode Diagram
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
00 00
PCA
Interrupt
0
1
x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F410/1/2/3
254 Rev. 1.1
25.2.3. 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-
Sp ee d Ou tp ut mod e .
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 25.6. PCA High-Speed Output Mode Diagram
Note: The initial state of the Toggle output is logic 1 and is initialized to this state wh en the module enter s
High Speed Output Mode.
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
PCA
Interrupt
0
1
00 0x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F410/1/2/3
Rev. 1.1 255
25.2.4. 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 25.1.
Equation 25.1. Square Wave Frequency Output
Where FPCA is the freque ncy of the clock sele cted by the CPS2-0 bit s 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. Fre-
quency Output Mode is enable d by setting the ECOM n, T O Gn, and PWMn bits in the PCA0CPMn r egiste r.
Figure 25.7. PCA Frequency Output Mode
FCEXn FPCA
2PCA0CPHn×
-----------------------------------------
=
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
8-bit
Comparator
PCA0L
Enable
PCA Timebase
000 0
match
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
PCA0CPHn8-bit AdderPCA0CPLn
Adder
Enable
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
1
C8051F410/1/2/3
256 Rev. 1.1
25.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be u sed inde pende ntly to gen erate 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 PCA0CPHn 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. When the count value in PCA0L overflows, the CEXn output will be
reset (see Figure 25.8). 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 so ftwar e intervention. Se tting the ECOMn and PWMn b it s in the PCA0CPM n register
enables 8-Bit Pulse Wid th Modulator mod e. The duty cycle for 8-Bit PWM Mode is given by Equation 25.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 25.2. 8-Bit PWM Duty Cycle
Using Equation 25.2, 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’.
Figure 25.8. PCA 8-Bit PWM Mode Diagram
DutyCycle 256 PCA0CPHn–()
256
---------------------------------------------------
=
8-bit
Comparator
PCA0L
PCA0CPLn
PCA0CPHn
CEXn
Crossbar P o rt I/O
Enable
Overflow
PCA Timebase
0000 0
Q
Q
SET
CLR
S
R
match
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
C8051F410/1/2/3
Rev. 1.1 257
25.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit captu re/compare mod-
ule defines the numbe r of PCA clocks fo r the low tim e of the PWM signal. When the PCA counter m atches
the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted
low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match inter-
rupts. 16-Bit PWM Mo de is enabled by se tting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn
register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help
synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by
Equation 25.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 25.3. 16-Bit PWM Duty Cycle
Using Equation 25.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CP n = 0xFF FF) . A 0% duty cycle ma y be generated by clearing the ECOMn bit to ‘0’.
Figure 25.9. PCA 16-Bit PWM Mode
25.3. Watchdog Timer Mode
A programmable watch dog timer (WDT) func tion is availa ble through the PCA Mo dule 5. Th e WDT is use d
to generate a reset if the time between writes to th e WDT up da te reg ister ( PCA0 CPH5 ) exceed a spe cified
limit. The WDT can be configured and en abled/disabled as needed by software.
With the WDTE bit set in the PCA0MD register, Module 5 operates as a watchdog timer (WDT). The
Module 5 high byte is comp ar ed to the PCA counter h igh byte; the Module 5 low byte holds the of fset 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.
DutyCycle 65536 PCA0CPn–()
65536
-----------------------------------------------------
=
PCA0CPLnPCA0CPHn
Enable
PCA Timebase
0000 0
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
1
16-bit Comparator
CEXn
Crossbar Port I/O
Overflow
Q
Q
SET
CLR
S
R
match
PCA0H PCA0L
C8051F410/1/2/3
258 Rev. 1.1
25.3.1. 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) ar e froze n .
• PCA Idle control bit (CIDL) is frozen.
• Module 5 is forced into software timer mode.
• Writes to the Module 5 mode reg ister (PCA0CPM5) 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 counte r run contro l (CR) will read zero if the WDT is enabled but user
software has not enabled the PCA counter. If a match occurs between PCA0CPH5 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 PCA0CPH5. Upon a PCA0CPH5 write, PCA0H plus the offset held in PCA0CPL5 is loade d
into PCA0CPH5 (See Figure 25.10).
Figure 25.10. PCA Module 5 with Watchdog Timer Enabled
PCA0H
Enable
PCA0L Overflow
Reset
PCA0CPL5 8-bit Adder
PCA0CPH5
Adder
Enable
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
Match
Write to
PCA0CPH5
8-bit
Comparator
C8051F410/1/2/3
Rev. 1.1 259
Note that the 8-bit offset held in PCA0CPH5 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 25.4, where PCA0L is the value of the PCA0L register
at the time of the update.
Equation 25.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH5 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF5 flag (PCA0CN.5) while the WDT is
enabled.
25.3.2. 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 PCA0CPL5 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’.
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 PCA0CPL5 defaults to 0x00. Using Equation 25.4, this results in a WDT
timeout interval of 3072 system clock cycles. Table 25.3 lists some example timeout intervals for typical
system clocks.
Offset 256 PCA0CPL5×()256 PCA0L–()+=
C8051F410/1/2/3
260 Rev. 1.1
Table 25.3. Watchdog Timer Timeout Intervals1
System Clock (Hz) PCA0CPL5 Timeout Interval (ms)
24,500,000 255 32.1
24,500,000 128 16.2
24,500,000 32 4.1
18,432,000 255 42.7
18,432,000 128 21.5
18,432,000 32 5.5
11,059,200 255 71.1
11,059,200 128 35.8
11,059,200 32 9.2
3,062,500 255 257
3,062,500 128 129.5
3,062,500 32 33.1
191,4062255 4109
191,4062128 2070
191,406232 530
32,000 255 24576
32,000 128 12384
32,000 32 3168
Notes:
1. Assumes SYSCLK / 12 as the PCA clock source, and a PCA0L
value of 0x00 at the update time.
2. Internal oscillator reset frequency.
C8051F410/1/2/3
Rev. 1.1 261
25.4. Register Descriptions for PCA
Following are deta iled descriptions of the special function registers related to the operation of the PCA.
SFR Definition 25.1. PCA0CN: PCA Control
Bit7: CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA Counter/T ime r 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.
Bit0: CCF5: PCA Module 5 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF5 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.
Bit4: CCF4: PCA Module 4 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit3: CCF3: PCA Module 3 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit2: 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.
Bit1: 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.
Bit0: 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.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CF CR CCF5 CCF4 CCF3 CCF2 CCF1 CCF0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xD8
C8051F410/1/2/3
262 Rev. 1.1
SFR Definition 25.2. PCA0MD: PCA Mode
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.
Bit6: WDTE: Watchdog Timer Enable
If this bit is set, PCA Module 5 is used as the watchdog timer.
0: Watchdog Timer disabled.
1: PCA Module 5 enabled as Watchdog Timer.
Bit5: 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 timebase source for the PCA counter.
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 interru p t.
1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to ‘1’, the PCA0MD register cannot be modified. To change the
contents of the PCA0MD register, the Watchdog Timer must first be disabled.
R/W R/W R/W R R/W R/W R/W R/W Reset Value
CIDL WDTE WDLCK - CPS2 CPS1 CPS0 ECF 01000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD9
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
011
High-to-low transitions on ECI (max rate = system clock
divided by 4)
1 0 0 System clock
101
External clock divided by 8*
110
smaRTClock clock divided by 8*
1 1 1 Reserved
*Note: External clock divided by 8 and smaRTClock clock divided by 8 are synchronized with the
system clock.
C8051F410/1/2/3
Rev. 1.1 263
SFR Definition 25.3. PCA0CPMn: PCA Capture/Compare Mode
Bit7: PWM16n: 16-bit Pulse Width Modulation Enable.
This bit selects 16- bit mode when Pulse Width Modulatio n mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
Bit6: ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA module n.
0: Disabled.
1: Enabled.
Bit5: CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA module n.
0: Disabled.
1: Enabled.
Bit4: CAPNn: Capture Ne gative Fu nc tion Ena ble.
This bit enables/di sables the negative edge capture for PCA module n.
0: Disabled.
1: Enabled.
Bit3: 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
register to be set to logic 1.
0: Disabled.
1: Enabled.
Bit2: 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 cau se the logic level on the
CEXn pin to togg le. If the PWMn b it is a lso set to logic 1, the modu le opera t es in Fr eq uency
Output Mode.
0: Disabled.
1: Enabled.
Bit1: PWMn: Pulse Widt h Modulation Mode Enable.
This bit enables/disables the PWM function for PCA module n. When enabled, a pulse width
modulated signal is outpu t on the CEXn pin. 8-bi t PWM is used if PWM16n is cleare d; 16-bit
mode is used if PWM16n is set to log ic 1. If the T OGn b it is also set, the modu le operate s in
Frequency Output Mode.
0: Disabled.
1: Enabled.
Bit0: 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.
R/W R /W R/W R/W R/W R/W R/W R/W Reset Value
PWM16n ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: PCA0CPM0: 0xDA, PCA0CPM1: 0xDB, PCA0CPM2: 0xDC, PCA0CPM3: 0xDD, PCA0CPM4: 0xDE,
PCA0CPM5: 0xCE
C8051F410/1/2/3
264 Rev. 1.1
SFR Definition 25.4. PCA0L: PCA Counter/Timer Low Byte
SFR Definition 25.5. PCA0H: PCA Counter/Timer High Byte
SFR Definition 25.6. PCA0CPLn: PCA Capture Module Low Byte
SFR Definition 25.7. PCA0CPHn: PCA Capture Module High Byte
Bits 7–0: PCA0L: PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xF9
Bits 7–0: PCA0H: PCA Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
SFR Address: 0xFA
Bits7–0: PCA0CPLn: PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
R/W R /W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: PCA0CPL0: 0xFB, PCA0CPL1: 0xE9, PCA0CPL2: 0xEB, PCA0CPL3: 0xED, PCA0CPL4: 0xFD, PCA0CPL5:
0xD2
Bits7–0: PCA0CPHn: PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: PCA0CPH0: 0xFC, PCA0CPH1: 0xEA, PCA0CPH2: 0xEC, PCA0CPH3: 0xEE, PCA0CPH4: 0xFE, PCA0CPH5:
0xD3
C8051F410/1/2/3
Rev. 1.1 265
26. C2 Interface
C8051F41x devices include an on-chip Silicon Laboratories 2-Wire (C2) debug interface to allow Flash
programming and in-system debugging with the production part installed in the end application. The C2
interface uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information
between the device and a host system. See the C2 Interface Specification for details on the C2 protocol.
26.1. C2 Interface Registers
The following describes the C2 registers necessary to perform Flash programming functions through the
C2 interface. All C2 reg isters are acce ssed through the C2 interface as de scribed in the C2 Interface Spec-
ification.
C2 Register Definition 26.1. C2ADD: C2 Address
C2 Register Definition 26.2. DEVICEID: C2 Device ID
Bits7-0: The C2ADD register is accessed via the C2 interface to select the target Data register for
C2 Data Read and Data Write commands.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Address Description
0x00 Selects the Device ID register for Data Read instructions (DEVICEID)
0x01 Selects the Revision ID register for Data Read instructions (REVID)
0x02 Selects the C2 Flash Pro gramming Control register for Data Read/W rite instructions
(FPCTL)
0xB4 Selects the C2 Flash Programming Data register for Data Read/Write instructions
(FPDAT)
This read-only register returns the 8-bit device ID: 0x0C (C8051F41x).
Reset Value
00001011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F410/1/2/3
266 Rev. 1.1
C2 Register Definition 26.3. REVID: C2 Revision ID
C2 Register Definition 26.4. FPCTL: C2 Flash Programming Control
C2 Register Definition 26.5. FPDAT: C2 Flash Programming Data
This read-only register returns the 8-bit revision ID: 0x00 (Revision A).
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7-0 FPCTL: Flash Programming Control Register.
This register is used to enable Flash programming via the C2 interface. To enable C2 Flash
programmi ng , th e follo win g co de s mu st be writt e n in order: 0x02, 0x01. Note that once C2
Flash programming is enabled, a system reset must be issued to resume normal operation.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7-0: FPDAT: C2 Flash Programming Data Register.
This register is used to pass Flash commands, addresses, and data during C2 Flash
accesses. Valid commands are listed below.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Code Command
0x06 Flash Block Read
0x07 Flash Block Write
0x08 Flash Page Erase
0x03 Device Erase
C8051F410/1/2/3
Rev. 1.1 267
26.2. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and
Flash programming functions may be performed. This is possible because C2 communication is typically
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 (/RST) and C2D (P2.0) pins. In most
applications, external resistors are required to isolate C2 interface traffic from the user application. A typi-
cal isolation configuration is shown in Figure 26.1.
Figure 26.1. Typical C2 Pin Sharing
The configuration in Figure 26.1 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 spe cific application.
C2D
C2CK
/Reset (a)
Input (b)
Output (c)
C2 Interface Master
C8051Fxxx
C8051F410/1/2/3
268 Rev. 1.1
DOCUMENT CHANGE LIST
Revision 0.7 to Revision 0.8
• Updated specification tables with most recently available characterization data.
• Corrected references to configuring pins for Analog Mode - Port Latch must contain a '1'.
•SFR Definition 5.6: Address correction to 0xBA.
• Added Figure 8.2 showing power connection diagram without using on-chip regulator.
•Section 9 : Removed references to "High Speed Analog Mode".
•Table 11.2 : Corrected SFR Name P2MDIN on location 0xF3.
•Section 14 : Corrected operational description of CRC engine.
•Section 18, Important Note on page 151 : Added "and have the same behavior as P0 in Normal Mode." to
last sentence.
•Section 19.2.2 : Inserted Step 3 "Release the crystal pins by writing ‘1's to the port latch."
•Section 19.3 : Added Figure 19.3 and text to describe behavior of clock multiplier with slower in put frequen-
cies.
•Section 21: Corrected SMBus maximum rate to 1/20th system clock.
•Table 21.4 : Made corrections to SMBus state descriptions.
•Figure 24.6 : Corrected T2RCLK Mux selection options.
•Figure 24.9 : Corrected T3RCLK Mux selection options.
•C2 Register Definition 26.2 : Corrected DEVICEID value to 0x0C.
Revision 0.8 to Revision 1.0
• Updated specification tables with full characterization data.
• Updated Flash write and erase procedures to include a write to FLSCL.3-0.
• Changed /RST pin comments in Table 4.1, “Pin Definitions for the C8051F41x,” on page 41 for the recom-
mended pull-up resistor.
• Changed the reset value of the SFR Definition 16.3. FLSCL: Flash Scale.
• Removed the "Optional GND Connection" from Figure 4.5. ’Typical QFN-28 Landing Diagram’ on page 48.
• Added a note regarding the maximum SYSCLK frequency to SFR Definition 19.4. CLKMUL: Clock Multi-
plier Control.
Revision 1.0 to Revision 1.1
• Updated Figure 4.3. ’LQFP-32 Package Diagram’ on page 46, Figure 4.5. ’QFN-28 Package Drawing’ on
page 48, and Figure 4.6. ’QFN-28 Recommended PCB Land Pattern’ on page 49.
• Added note that VIO must be > VDD in Table 3.1, “Global DC Electrical Characteristics,” on page 36.
• Added information about ADC0 output register auto-clearing in SFR Definition 5.2.
• Corrected ADC0 Tracking time equation in SFR Definition 5.6.
• Clarified Voltage Regulator Electrical Specifications in Table 8.1 on page 82.
• Added information about 16-bit and 32-bit CRC algorithms in Section 14.
C8051F410/1/2/3
Rev. 1.1 269
NOTES:
Disclaimer
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using or intending to use the Silicon Laboratories products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific
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