C8051F412-GQ

C8051F410/1/2/3 2.0 V, 32/16 kB Flash, smaRTClock, 12-bit ADC 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 • • Programmable hysteresis and response time Configurable as wake-up or reset source Two 12-Bit Current Mode DACs Two Comparators - POR/Brownout Detector - Voltage Reference—1.5, 2.2 V (programmable) On-Chip Debug - On-chip debug circuitry facilitates full-speed, nonintrusive 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 Rev. 1.2 11/22 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 Copyright © 2022 by Silicon Laboratories C8051F41x C8051F410/1/2/3 Table of Contents 1. System Overview.................................................................................................... 15 1.1. CIP-51™ Microcontroller................................................................................... 21 1.1.1. Fully 8051 Compatible Instruction Set...................................................... 21 1.1.2. Improved Throughput ............................................................................... 21 1.1.3. Additional Features .................................................................................. 21 1.2. On-Chip Debug Circuitry................................................................................... 22 1.3. On-Chip Memory............................................................................................... 23 1.4. Operating Modes .............................................................................................. 24 1.5. 12-Bit Analog to Digital Converter..................................................................... 25 1.6. Two 12-bit Current-Mode DACs........................................................................ 25 1.7. Programmable Comparators............................................................................. 26 1.8. Cyclic Redundancy Check Unit......................................................................... 27 1.9. Voltage Regulator ............................................................................................. 27 1.10.Serial Ports ....................................................................................................... 27 1.11.smaRTClock (Real Time Clock) ....................................................................... 28 1.12.Port Input/Output .............................................................................................. 29 1.13.Programmable Counter Array........................................................................... 30 2. Absolute Maximum Ratings .................................................................................. 31 3. Global DC Electrical Characteristics .................................................................... 32 4. Pinout and Package Definitions............................................................................ 36 5. 12-Bit ADC (ADC0).................................................................................................. 45 5.1. Analog Multiplexer ............................................................................................ 45 5.2. Temperature Sensor ......................................................................................... 46 5.3. ADC0 Operation................................................................................................ 46 5.3.1. Starting a Conversion............................................................................... 47 5.3.2. Tracking Modes........................................................................................ 47 5.3.3. Timing....................................................................................................... 48 5.3.4. Burst Mode ............................................................................................... 50 5.3.5. Output Conversion Code.......................................................................... 51 5.3.6. Settling Time Requirements ..................................................................... 52 5.4. Programmable Window Detector ...................................................................... 57 5.4.1. Window Detector In Single-Ended Mode ................................................. 60 6. 12-Bit Current Mode DACs (IDA0 and IDA1) ........................................................ 63 6.1. IDAC Output Scheduling................................................................................... 63 6.1.1. Update Output On-Demand ..................................................................... 63 6.1.2. Update Output Based on Timer Overflow ................................................ 64 6.1.3. Update Output Based on CNVSTR Edge................................................. 64 6.2. IDAC Output Mapping....................................................................................... 64 6.3. IDAC External Pin Connections ........................................................................ 67 7. Voltage Reference .................................................................................................. 70 8. Voltage Regulator (REG0)...................................................................................... 73 9. Comparators ......................................................................................................... 75 10. CIP-51 Microcontroller ........................................................................................... 85 2 Rev. 1.2 C8051F410/1/2/3 10.1.Instruction Set................................................................................................... 86 10.1.1.Instruction and CPU Timing ..................................................................... 86 10.1.2.MOVX Instruction and Program Memory ................................................. 87 10.2.Register Descriptions ....................................................................................... 90 10.3.Power Management Modes.............................................................................. 93 10.3.1.Idle Mode ................................................................................................. 94 10.3.2.Stop Mode................................................................................................ 94 10.3.3.Suspend Mode ......................................................................................... 94 11. Memory Organization and SFRs ........................................................................... 95 11.1.Program Memory.............................................................................................. 95 11.2.Data Memory .................................................................................................... 96 11.3.General Purpose Registers .............................................................................. 96 11.4.Bit Addressable Locations ................................................................................ 96 11.5.Stack................................................................................................................. 96 11.6.Special Function Registers............................................................................... 97 12. Interrupt Handler .................................................................................................. 102 12.1.MCU Interrupt Sources and Vectors............................................................... 102 12.2.Interrupt Priorities ........................................................................................... 102 12.3.Interrupt Latency............................................................................................. 102 12.4.Interrupt Register Descriptions ....................................................................... 104 12.5.External Interrupts .......................................................................................... 109 13. Prefetch Engine .................................................................................................... 111 14. Cyclic Redundancy Check Unit (CRC0) ............................................................. 112 14.1.16-bit CRC Algorithm...................................................................................... 112 14.2.32-bit CRC Algorithm...................................................................................... 114 14.3.Preparing for a CRC Calculation .................................................................... 115 14.4.Performing a CRC Calculation ....................................................................... 115 14.5.Accessing the CRC0 Result ........................................................................... 115 14.6.CRC0 Bit Reverse Feature............................................................................. 115 15. Reset Sources....................................................................................................... 118 15.1.Power-On Reset ............................................................................................. 119 15.2.Power-Fail Reset / VDD Monitor .................................................................... 120 15.3.External Reset ................................................................................................ 121 15.4.Missing Clock Detector Reset ........................................................................ 121 15.5.Comparator0 Reset ........................................................................................ 122 15.6.PCA Watchdog Timer Reset .......................................................................... 122 15.7.Flash Error Reset ........................................................................................... 122 15.8.smaRTClock (Real Time Clock) Reset........................................................... 122 15.9.Software Reset ............................................................................................... 122 16. Flash Memory ....................................................................................................... 125 16.1.Programming The Flash Memory ................................................................... 125 16.1.1.Flash Lock and Key Functions ............................................................... 125 16.1.2.Flash Erase Procedure .......................................................................... 125 16.1.3.Flash Write Procedure ........................................................................... 126 16.2.Non-volatile Data Storage .............................................................................. 127 Rev. 1.2 3 C8051F410/1/2/3 16.3.Security Options ............................................................................................. 127 16.4.Flash Write and Erase Guidelines .................................................................. 129 16.4.1.VDD Maintenance and the VDD Monitor ............................................... 129 16.4.2.16.4.2 PSWE Maintenance .................................................................... 130 16.4.3.System Clock ......................................................................................... 130 16.5.Flash Read Timing ......................................................................................... 132 17. External RAM ........................................................................................................ 134 18. Port Input/Output.................................................................................................. 135 18.1.Priority Crossbar Decoder .............................................................................. 137 18.2.Port I/O Initialization ....................................................................................... 139 18.3.General Purpose Port I/O ............................................................................... 142 19. Oscillators ............................................................................................................. 152 19.1.Programmable Internal Oscillator ................................................................... 152 19.1.1.Internal Oscillator Suspend Mode .......................................................... 153 19.2.External Oscillator Drive Circuit...................................................................... 155 19.2.1.Clocking Timers Directly Through the External Oscillator...................... 155 19.2.2.External Crystal Example....................................................................... 155 19.2.3.External RC Example............................................................................. 157 19.2.4.External Capacitor Example................................................................... 157 19.3.Clock Multiplier ............................................................................................... 159 19.4.System Clock Selection.................................................................................. 161 20. smaRTClock (Real Time Clock)........................................................................... 163 20.1.smaRTClock Interface .................................................................................... 164 20.1.1.smaRTClock Lock and Key Functions ................................................... 164 20.1.2.Using RTC0ADR and RTC0DAT to Access smaRTClock Internal Registers 164 20.1.3.smaRTClock Interface Autoread Feature............................................... 164 20.1.4.RTC0ADR Autoincrement Feature......................................................... 165 20.2.smaRTClock Clocking Sources ...................................................................... 168 20.2.1.Using the smaRTClock Oscillator in Crystal Mode ................................ 168 20.2.2.Using the smaRTClock Oscillator in Self-Oscillate Mode ...................... 168 20.2.3.Automatic Gain Control (Crystal Mode Only) ......................................... 169 20.2.4.smaRTClock Bias Doubling ................................................................... 169 20.2.5.smaRTClock Missing Clock Detector..................................................... 169 20.3.smaRTClock Timer and Alarm Function......................................................... 171 20.3.1.Setting and Reading the smaRTClock Timer Value............................... 171 20.3.2.Setting a smaRTClock Alarm ................................................................. 172 20.4.Backup Regulator and RAM ........................................................................... 173 21. SMBus ................................................................................................................... 177 21.1.Supporting Documents ................................................................................... 178 21.2.SMBus Configuration...................................................................................... 178 21.3.SMBus Operation ........................................................................................... 178 21.3.1.Arbitration............................................................................................... 179 21.3.2.Clock Low Extension.............................................................................. 179 21.3.3.SCL Low Timeout................................................................................... 180 4 Rev. 1.2 C8051F410/1/2/3 21.3.4.SCL High (SMBus Free) Timeout .......................................................... 180 21.4.Using the SMBus............................................................................................ 180 21.4.1.SMBus Configuration Register............................................................... 181 21.4.2.SMB0CN Control Register ..................................................................... 184 21.4.3.Data Register ......................................................................................... 187 21.5.SMBus Transfer Modes.................................................................................. 187 21.5.1.Master Transmitter Mode ....................................................................... 187 21.5.2.Master Receiver Mode ........................................................................... 188 21.5.3.Slave Receiver Mode ............................................................................. 189 21.5.4.Slave Transmitter Mode ......................................................................... 190 21.6.SMBus Status Decoding................................................................................. 190 22. UART0.................................................................................................................... 193 22.1.Enhanced Baud Rate Generation................................................................... 194 22.2.Operational Modes ......................................................................................... 195 22.2.1.8-Bit UART ............................................................................................. 195 22.2.2.9-Bit UART ............................................................................................. 196 22.3.Multiprocessor Communications .................................................................... 196 23. Enhanced Serial Peripheral Interface (SPI0)...................................................... 203 23.1.Signal Descriptions......................................................................................... 204 23.1.1.Master Out, Slave In (MOSI).................................................................. 204 23.1.2.Master In, Slave Out (MISO).................................................................. 204 23.1.3.Serial Clock (SCK) ................................................................................. 204 23.1.4.Slave Select (NSS) ................................................................................ 204 23.2.SPI0 Master Mode Operation ......................................................................... 205 23.3.SPI0 Slave Mode Operation ........................................................................... 206 23.4.SPI0 Interrupt Sources ................................................................................... 207 23.5.Serial Clock Timing......................................................................................... 207 23.6.SPI Special Function Registers ...................................................................... 208 24. Timers.................................................................................................................... 216 24.1.Timer 0 and Timer 1 ....................................................................................... 216 24.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 216 24.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 218 24.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 218 24.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 219 24.2.Timer 2 ........................................................................................................... 224 24.2.1.16-bit Timer with Auto-Reload................................................................ 224 24.2.2.8-bit Timers with Auto-Reload................................................................ 225 24.2.3.External/smaRTClock Capture Mode..................................................... 226 24.3.Timer 3 ........................................................................................................... 229 24.3.1.16-bit Timer with Auto-Reload................................................................ 229 24.3.2.8-bit Timers with Auto-Reload................................................................ 230 24.3.3.External/smaRTClock Capture Mode..................................................... 231 Rev. 1.2 5 C8051F410/1/2/3 25. Programmable Counter Array (PCA0) ................................................................ 234 25.1.PCA Counter/Timer ........................................................................................ 235 25.2.Capture/Compare Modules ............................................................................ 236 25.2.1.Edge-triggered Capture Mode................................................................ 237 25.2.2.Software Timer (Compare) Mode........................................................... 238 25.2.3.High Speed Output Mode....................................................................... 239 25.2.4.Frequency Output Mode ........................................................................ 240 25.2.5.8-Bit Pulse Width Modulator Mode......................................................... 241 25.2.6.16-Bit Pulse Width Modulator Mode....................................................... 242 25.3.Watchdog Timer Mode ................................................................................... 242 25.3.1.Watchdog Timer Operation .................................................................... 243 25.3.2.Watchdog Timer Usage ......................................................................... 244 25.4.Register Descriptions for PCA........................................................................ 246 26. C2 Interface ........................................................................................................... 250 26.1.C2 Interface Registers.................................................................................... 250 26.2.C2 Pin Sharing ............................................................................................... 252 6 Rev. 1.2 C8051F410/1/2/3 List of Figures 1. System Overview Figure 1.1. C8051F410 Block Diagram .................................................................... 17 Figure 1.2. C8051F411 Block Diagram .................................................................... 18 Figure 1.3. C8051F412 Block Diagram .................................................................... 19 Figure 1.4. C8051F413 Block Diagram .................................................................... 20 Figure 1.5. Development/In-System Debug Diagram............................................... 22 Figure 1.6. Memory Map .......................................................................................... 23 Figure 1.7. 12-Bit ADC Block Diagram..................................................................... 25 Figure 1.8. IDAC Block Diagram .............................................................................. 26 Figure 1.9. Comparators Block Diagram .................................................................. 27 Figure 1.10. smaRTClock Block Diagram ................................................................ 28 Figure 1.11. Port I/O Functional Block Diagram ....................................................... 29 Figure 1.12. PCA Block Diagram.............................................................................. 30 4. Pinout and Package Definitions Figure 4.1. LQFP-32 Pinout Diagram (Top View) .................................................... 39 Figure 4.2. QFN-28 Pinout Diagram (Top View) ...................................................... 40 Figure 4.3. LQFP-32 Package Diagram ................................................................... 41 Figure 4.4. LQFP-32 Recommended PCB Land Pattern ......................................... 42 Figure 4.5. QFN-28 Package Drawing ..................................................................... 43 Figure 4.6. QFN-28 Recommended PCB Land Pattern ........................................... 44 5. 12-Bit ADC (ADC0) Figure 5.1. ADC0 Functional Block Diagram............................................................ 45 Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 46 Figure 5.3. ADC0 Tracking Modes ........................................................................... 48 Figure 5.4. 12-Bit ADC Tracking Mode Example ..................................................... 49 Figure 5.5. 12-Bit ADC Burst Mode Example with Repeat Count Set to 4............... 50 Figure 5.6. ADC0 Equivalent Input Circuits.............................................................. 52 Figure 5.7. ADC Window Compare Example: Right-Justified Single-Ended Data ... 60 Figure 5.8. ADC Window Compare Example: Left-Justified Single-Ended Data ..... 60 6. 12-Bit Current Mode DACs (IDA0 and IDA1) Figure 6.1. IDAC Functional Block Diagram............................................................. 63 Figure 6.2. IDAC Data Word Mapping...................................................................... 64 Figure 6.3. IDAC Pin Connections ........................................................................... 68 7. Voltage Reference Figure 7.1. Voltage Reference Functional Block Diagram ....................................... 70 8. Voltage Regulator (REG0) Figure 8.1. External Capacitors for Voltage Regulator Input/Output ........................ 73 Figure 8.2. External Capacitors for Voltage Regulator Input/Output ........................ 73 9. Comparators Figure 9.1. Comparator0 Functional Block Diagram ................................................ 75 Figure 9.2. Comparator1 Functional Block Diagram ................................................ 76 Figure 9.3. Comparator Hysteresis Plot ................................................................... 77 Rev. 1.2 7 C8051F410/1/2/3 10. CIP-51 Microcontroller Figure 10.1. CIP-51 Block Diagram.......................................................................... 85 11. Memory Organization and SFRs Figure 11.1. Memory Map ........................................................................................ 95 14. Cyclic Redundancy Check Unit (CRC0) Figure 14.1. CRC0 Block Diagram ......................................................................... 112 Figure 14.2. Bit Reverse Register .......................................................................... 115 15. Reset Sources Figure 15.1. Reset Sources.................................................................................... 118 Figure 15.2. Power-On Reset Timing ..................................................................... 119 Figure 15.3. VDD Monitor Reset Timing................................................................. 120 16. Flash Memory Figure 16.1. Flash Program Memory Map.............................................................. 127 18. Port Input/Output Figure 18.1. Port I/O Functional Block Diagram ..................................................... 135 Figure 18.2. Port I/O Cell Block Diagram ............................................................... 136 Figure 18.3. Crossbar Priority Decoder with No Pins Skipped ............................... 137 Figure 18.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 138 Figure 18.5. Port 0 Input Overdrive Current Range................................................ 140 19. Oscillators Figure 19.1. Oscillator Diagram.............................................................................. 152 Figure 19.2. 32.768 kHz External Crystal Example................................................ 156 Figure 19.3. Example Clock Multiplier Output ........................................................ 159 20. smaRTClock (Real Time Clock) Figure 20.1. smaRTClock Block Diagram .............................................................. 163 21. SMBus Figure 21.1. SMBus Block Diagram ....................................................................... 177 Figure 21.2. Typical SMBus Configuration ............................................................. 178 Figure 21.3. SMBus Transaction ............................................................................ 179 Figure 21.4. Typical SMBus SCL Generation......................................................... 182 Figure 21.5. Typical Master Transmitter Sequence................................................ 188 Figure 21.6. Typical Master Receiver Sequence.................................................... 188 Figure 21.7. Typical Slave Receiver Sequence...................................................... 189 Figure 21.8. Typical Slave Transmitter Sequence.................................................. 190 22. UART0 Figure 22.1. UART0 Block Diagram ....................................................................... 193 Figure 22.2. UART0 Baud Rate Logic .................................................................... 194 Figure 22.3. UART Interconnect Diagram .............................................................. 195 Figure 22.4. 8-Bit UART Timing Diagram............................................................... 195 Figure 22.5. 9-Bit UART Timing Diagram............................................................... 196 Figure 22.6. UART Multi-Processor Mode Interconnect Diagram .......................... 197 23. Enhanced Serial Peripheral Interface (SPI0) Figure 23.1. SPI Block Diagram ............................................................................. 203 Figure 23.2. Multiple-Master Mode Connection Diagram ....................................... 206 Figure 23.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 206 8 Rev. 1.2 C8051F410/1/2/3 Figure 23.4. 4-Wire Single Master and Slave Mode Connection Diagram ............. 206 Figure 23.5. Data/Clock Timing Relationship ......................................................... 208 Figure 23.6. SPI Master Timing (CKPHA = 0)........................................................ 213 Figure 23.7. SPI Master Timing (CKPHA = 1)........................................................ 213 Figure 23.8. SPI Slave Timing (CKPHA = 0).......................................................... 214 Figure 23.9. SPI Slave Timing (CKPHA = 1).......................................................... 214 24. Timers Figure 24.1. T0 Mode 0 Block Diagram.................................................................. 217 Figure 24.2. T0 Mode 2 Block Diagram.................................................................. 218 Figure 24.3. T0 Mode 3 Block Diagram.................................................................. 219 Figure 24.4. Timer 2 16-Bit Mode Block Diagram .................................................. 224 Figure 24.5. Timer 2 8-Bit Mode Block Diagram .................................................... 225 Figure 24.6. Timer 2 Capture Mode Block Diagram ............................................... 226 Figure 24.7. Timer 3 16-Bit Mode Block Diagram .................................................. 229 Figure 24.8. Timer 3 8-Bit Mode Block Diagram .................................................... 230 Figure 24.9. Timer 3 Capture Mode Block Diagram ............................................... 231 25. Programmable Counter Array (PCA0) Figure 25.1. PCA Block Diagram............................................................................ 234 Figure 25.2. PCA Counter/Timer Block Diagram.................................................... 235 Figure 25.3. PCA Interrupt Block Diagram ............................................................. 236 Figure 25.4. PCA Capture Mode Diagram.............................................................. 237 Figure 25.5. PCA Software Timer Mode Diagram .................................................. 238 Figure 25.6. PCA High-Speed Output Mode Diagram............................................ 239 Figure 25.7. PCA Frequency Output Mode ............................................................ 240 Figure 25.8. PCA 8-Bit PWM Mode Diagram ......................................................... 241 Figure 25.9. PCA 16-Bit PWM Mode...................................................................... 242 Figure 25.10. PCA Module 5 with Watchdog Timer Enabled ................................. 243 26. C2 Interface Figure 26.1. Typical C2 Pin Sharing....................................................................... 252 Rev. 1.2 9 C8051F410/1/2/3 List of Tables 1. System Overview Table 1.1. Product Selection Guide ......................................................................... 16 Table 1.2. Operating Modes Summary .................................................................... 24 3. Global DC Electrical Characteristics Table 3.1. Index to Electrical Characteristics Tables ............................................... 35 4. Pinout and Package Definitions Table 4.1. Pin Definitions for the C8051F41x .......................................................... 36 Table 4.2. LQFP-32 Package Dimensions .............................................................. 41 Table 4.3. LQFP-32 PCB Land Pattern Dimensions ............................................... 42 Table 4.4. QFN-28 Package Dimensions ................................................................ 43 Table 4.5. QFN-28 PCB Land Pattern Dimensions ................................................. 44 5. 12-Bit ADC (ADC0) Table 5.1. ADC0 Examples of Right- and Left-Justified Samples ........................... 51 Table 5.2. ADC0 Repeat Count Examples at Various Input Voltages ..................... 51 10. CIP-51 Microcontroller Table 10.1. CIP-51 Instruction Set Summary1 ......................................................................... 87 11. Memory Organization and SFRs Table 11.1. Special Function Register (SFR) Memory Map .................................... 97 Table 11.2. Special Function Registers ................................................................... 98 12. Interrupt Handler Table 12.1. Interrupt Summary .............................................................................. 103 14. Cyclic Redundancy Check Unit (CRC0) Table 14.1. Example 16-bit CRC Outputs ............................................................. 113 Table 14.2. Example 32-bit CRC Outputs ............................................................. 115 16. Flash Memory Table 16.1. Flash Security Summary .................................................................... 128 20. smaRTClock (Real Time Clock) Table 20.1. smaRTClock Internal Registers .......................................................... 165 21. SMBus Table 21.1. SMBus Clock Source Selection .......................................................... 181 Table 21.2. Minimum SDA Setup and Hold Times ................................................ 182 Table 21.3. Sources for Hardware Changes to SMB0CN ..................................... 186 Table 21.4. SMBus Status Decoding ..................................................................... 191 22. UART0 Table 22.1. Timer Settings for Standard Baud Rates Using the Internal Oscillator ............................................................... 200 Table 22.2. Timer Settings for Standard Baud Rates Using an External 25.0 MHz Oscillator ............................................... 200 Table 22.3. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator ......................................... 201 Table 22.4. Timer Settings for Standard Baud Rates Using an External 18.432 MHz Oscillator ........................................... 201 10 Rev. 1.2 C8051F410/1/2/3 Table 22.5. Timer Settings for Standard Baud Rates Using an External 11.0592 MHz Oscillator ......................................... 202 Table 22.6. Timer Settings for Standard Baud Rates Using an External 3.6864 MHz Oscillator ........................................... 202 25. Programmable Counter Array (PCA0) Table 25.1. PCA Timebase Input Options ............................................................. 235 Table 25.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 236 Table 25.3. Watchdog Timer Timeout Intervals1 ................................................... 245 Rev. 1.2 11 C8051F410/1/2/3 List of Registers SFR Definition 5.1. ADC0MX: ADC0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . 53 SFR Definition 5.2. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 SFR Definition 5.3. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 55 SFR Definition 5.4. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 SFR Definition 5.5. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 SFR Definition 5.6. ADC0TK: ADC0 Tracking Mode Select . . . . . . . . . . . . . . . . . . . . 57 SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 58 SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 58 SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 59 SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 59 SFR Definition 6.1. IDA0CN: IDA0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 SFR Definition 6.2. IDA0H: IDA0 Data High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 SFR Definition 6.3. IDA0L: IDA0 Data Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 SFR Definition 6.4. IDA1CN: IDA1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 SFR Definition 6.5. IDA1H: IDA0 Data High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 SFR Definition 6.6. IDA1L: IDA1 Data Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 SFR Definition 7.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 SFR Definition 8.1. REG0CN: Regulator Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 SFR Definition 9.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 SFR Definition 9.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 79 SFR Definition 9.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 80 SFR Definition 9.4. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 81 SFR Definition 9.5. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 82 SFR Definition 9.6. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 SFR Definition 10.1. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 SFR Definition 10.2. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 SFR Definition 10.3. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 SFR Definition 10.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 SFR Definition 10.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 SFR Definition 10.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 SFR Definition 10.7. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 SFR Definition 12.1. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 SFR Definition 12.2. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 SFR Definition 12.3. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . 106 SFR Definition 12.4. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . 107 SFR Definition 12.5. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . . 108 SFR Definition 12.6. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . . 108 SFR Definition 12.7. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . 110 SFR Definition 13.1. PFE0CN: Prefetch Engine Control . . . . . . . . . . . . . . . . . . . . . . 111 SFR Definition 14.1. CRC0CN: CRC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 SFR Definition 14.2. CRC0IN: CRC0 Data Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 SFR Definition 14.3. CRC0DAT: CRC0 Data Output . . . . . . . . . . . . . . . . . . . . . . . . . 117 SFR Definition 14.4. CRC0FLIP: CRC0 Bit Flip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 12 Rev. 1.2 C8051F410/1/2/3 SFR Definition 15.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . 121 SFR Definition 15.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 SFR Definition 16.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 131 SFR Definition 16.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 SFR Definition 16.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 SFR Definition 16.4. ONESHOT: Flash Oneshot Period . . . . . . . . . . . . . . . . . . . . . . 133 SFR Definition 17.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 134 SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 141 SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 142 SFR Definition 18.3. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 SFR Definition 18.4. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 SFR Definition 18.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 144 SFR Definition 18.6. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 SFR Definition 18.7. P0MAT: Port0 Match . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 SFR Definition 18.8. P0MASK: Port0 Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 SFR Definition 18.9. P0ODEN: Port0 Overdrive Mode . . . . . . . . . . . . . . . . . . . . . . . . 145 SFR Definition 18.10. P1: Port1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 SFR Definition 18.11. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 SFR Definition 18.12. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 147 SFR Definition 18.13. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 SFR Definition 18.14. P1MAT: Port1 Match . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 SFR Definition 18.15. P1MASK: Port1 Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 SFR Definition 18.16. P2: Port2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 SFR Definition 18.17. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 SFR Definition 18.18. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 150 SFR Definition 18.19. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 SFR Definition 19.1. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 154 SFR Definition 19.2. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 154 SFR Definition 19.3. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 158 SFR Definition 19.4. CLKMUL: Clock Multiplier Control . . . . . . . . . . . . . . . . . . . . . . . 160 SFR Definition 19.5. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 SFR Definition 20.1. RTC0KEY: smaRTClock Lock and Key . . . . . . . . . . . . . . . . . . . 166 SFR Definition 20.2. RTC0ADR: smaRTClock Address . . . . . . . . . . . . . . . . . . . . . . 167 SFR Definition 20.3. RTC0DAT: smaRTClock Data . . . . . . . . . . . . . . . . . . . . . . . . . 168 SFR Definition 21.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 183 SFR Definition 21.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 SFR Definition 21.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 SFR Definition 22.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 198 SFR Definition 22.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 199 SFR Definition 23.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 209 SFR Definition 23.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 SFR Definition 23.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 SFR Definition 23.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 SFR Definition 24.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 SFR Definition 24.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 Rev. 1.2 13 C8051F410/1/2/3 SFR Definition 24.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 SFR Definition 24.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 SFR Definition 24.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 SFR Definition 24.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 SFR Definition 24.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 SFR Definition 24.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 SFR Definition 24.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 228 SFR Definition 24.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 228 SFR Definition 24.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 SFR Definition 24.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 SFR Definition 24.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 SFR Definition 24.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 233 SFR Definition 24.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 233 SFR Definition 24.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 SFR Definition 24.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 SFR Definition 25.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 SFR Definition 25.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 SFR Definition 25.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 248 SFR Definition 25.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 249 SFR Definition 25.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 249 SFR Definition 25.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 249 SFR Definition 25.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 249 14 Rev. 1.2 C8051F410/1/2/3 1. System Overview C8051F41x devices are fully integrated, low power, mixed-signal system-on-a-chip MCUs. Highlighted features 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-purpose 16-bit timers Programmable Counter/Timer Array (PCA) with six capture/compare modules and Watchdog Timer function Hardware smaRTClock (Real Time Clock) operates down 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 regulator) 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. Rev. 1.2 15 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 16 RAM Flash Memory MIPS (Peak) Calibrated Internal 24.5 MHz Oscillator Ordering Part Number C8051F410/1/2/3 Table 1.1. Product Selection Guide *Note: Not recommended for new designs. Rev. 1.2 C8051F410/1/2/3 Figure 1.1. C8051F410 Block Diagram Rev. 1.2 17 C8051F410/1/2/3 Figure 1.2. C8051F411 Block Diagram 18 Rev. 1.2 C8051F410/1/2/3 Figure 1.3. C8051F412 Block Diagram Rev. 1.2 19 C8051F410/1/2/3 Figure 1.4. C8051F413 Block Diagram 20 Rev. 1.2 C8051F410/1/2/3 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 software. The C8051F41x family has a superset of all the peripherals included with a standard 8052. 1.1.2. Improved Throughput The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 12-to-24 MHz. By contrast, the CIP51 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 running at 50 MHz, it has a peak throughput of 50 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute 1 2 2/4 3 3/5 4 5 4/6 6 8 Number of Instructions 26 50 5 10 7 5 2 1 2 1 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 independently of the controller core and interrupt the controller only when necessary. By requiring less intervention 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 external crystal, 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 oscillator 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. Rev. 1.2 21 C8051F410/1/2/3 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 single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized. The C8051F410DK development kit provides all the hardware and software necessary to develop application 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 required cables and wall-mount power supply. The development kit requires a computer 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, compared 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 performance of the precision analog peripherals. Figure 1.5. Development/In-System Debug Diagram 22 Rev. 1.2 C8051F410/1/2/3 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 dual-mapped. Indirect addressing accesses the upper 128 bytes of general purpose RAM, and direct addressing accesses the 128-byte SFR address space. The lower 128 bytes of RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of general purpose registers, and the next 16 bytes can be byte addressable or bit addressable. Program memory consists of 32 kB (‘F410/1) or 16 kB (‘F412/3) of Flash. This memory may be reprogrammed in-system in 512 byte sectors and requires no special off-chip programming voltage. Figure 1.6. Memory Map Rev. 1.2 23 C8051F410/1/2/3 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 wakening event occurs, which also halts all peripherals using SYSCLK. In Stop mode, the CPU is halted, all interrupts and timers are inactive, and the internal oscillator is stopped. The various operating modes are described in Table 1.2 below: Table 1.2. Operating Modes Summary Power Consumption How Entered? How Exited? SYSCLK active CPU active (accessing Flash) Peripherals active or inactive depending on user settings smaRTClock active or inactive Full — — 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 SYSCLK inactive CPU inactive (not accessing Flash) Peripherals enabled (but not operating) or disabled depending on user settings smaRTClock active or inactive Low SUSPEND (OSCICN.5) Wakening event or external/MCD reset 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 Properties Active • • • • • • Idle • • • • Suspend • • • • Stop • • See Section “10.3. Power Management Modes” on page 93 for Idle and Stop mode details. See Section “19.1.1. Internal Oscillator Suspend Mode” on page 153 for more information on Suspend mode. 24 Rev. 1.2 C8051F410/1/2/3 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 multiplexer and a maximum throughput of 200 ksps. The ADC system includes a configurable analog multiplexer that selects the positive ADC input, which is measured with respect to GND. Ports 0–2 are available as ADC inputs; additionally, the on-chip Temperature Sensor output and the core supply voltage (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 periodic 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 shutdown state, acquire and accumulate samples, then re-enter the low power shutdown state without CPU intervention. Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is either within or outside of a specified range. The ADC can monitor a key voltage continuously in background 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 maximum 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 seamless full-scale changes, 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. Rev. 1.2 25 C8051F410/1/2/3 Figure 1.8. IDAC Block Diagram 1.7. Programmable Comparators C8051F41x devices include two software-configurable voltage comparators with an input multiplexer. Each comparator offers programmable response time and hysteresis and two outputs that are optionally available 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. Comparator0 may also be configured as a reset source. A block diagram of the comparator is shown in Figure 1.9. 26 Rev. 1.2 C8051F410/1/2/3 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. When enabled, the output of REG0 powers the device and drives the VDD pin. The voltage regulator can be used 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. Rev. 1.2 27 C8051F410/1/2/3 1.11. smaRTClock (Real Time Clock) C8051F41x devices include a smaRTClock Peripheral (Real Time Clock). The smaRTClock has a dedicated 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 smaRTClock peripheral remains fully functional even if the core supply 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 1 V. The switchover logic powers smaRTClock 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 28 Rev. 1.2 C8051F410/1/2/3 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 configured as a digital 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 generalpurpose port I/O, digital, and analog resources needed for the application. Figure 1.11. Port I/O Functional Block Diagram Rev. 1.2 29 C8051F410/1/2/3 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 overflow, 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: EdgeTriggered 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 following a system reset. The PCA Capture/Compare Module I/O and the External Clock Input may be routed to Port I/O using the digital crossbar. Figure 1.12. PCA Block Diagram 30 Rev. 1.2 C8051F410/1/2/3 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 Voltage on any Port I/O Pin (except Port 0 pins) or RSTb 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 — — 500 mA *Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Rev. 1.2 31 C8051F410/1/2/3 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 Output Current = 1 mA 2.15 — 5.25 V Core Supply Voltage (VDD) 2.0 — 2.75 V I/O Supply Voltage (VIO)2 2.0 — 5.25 V Backup Supply Voltage (VRTC-BACKUP)3 1.0 — 5.25 V — — — 0.65 0.9 1.4 1.5 1.8 2.5 μA μA μA — — — 0.7 0.92 1.45 — — — μA μA μA — — — 0.72 0.95 1.5 1.6 1.85 2.6 μA μA μA Core Supply RAM Data Retention Voltage — 1.5 — V SYSCLK (System Clock)4,5 0 — 50 MHz Supply Input Voltage (VREGIN)1 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 Notes: 1. For more information on VREGIN characteristics, see Table 8.1 on page 74. 2. VIO must be equal to or greater than VDD. 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 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 = 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 interest 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. 32 Rev. 1.2 C8051F410/1/2/3 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 Specified Operating Temperature Range Min Typ Max Units –40 — +85 °C Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash) Core Supply Current (IDD)6 Supply Sensitivity (IDD)6,7 Frequency Sensitivity (IDD)6,8 VDD = 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 F = 25 MHz F = 1 MHz 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 — — — — 13 0.30 5.5 9.5 30 0.5 6.5 12 μA mA mA mA — — — — 17 0.43 8.3 13.5 40 0.65 9.5 15 μA mA mA mA — — 114 100 — — %/V %/V — — 0.27 0.16 — — mA/MHz mA/MHz — — 0.39 0.2 — — mA/MHz mA/MHz Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash) Notes: 1. For more information on VREGIN characteristics, see Table 8.1 on page 74. 2. VIO must be equal to or greater than VDD. 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 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 = 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 interest 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. Rev. 1.2 33 C8051F410/1/2/3 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 Core Supply Current (IDD)6 Supply Sensitivity (IDD)6,7 Frequency Sensitivity (IDD)6,9 Conditions VDD = 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 F = 25 MHz F = 1 MHz 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 Min Typ Max Units — — — — 10 0.15 2.8 5 25 0.25 3.3 11 μA mA mA mA — — — — 11 0.21 3.8 7.5 30 0.37 4.3 8.0 μA mA mA mA — — 75 68 — — %/V %/V — — 0.14 0.1 — — mA/MHz mA/MHz — — 0.19 0.13 — — 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 running, VDD = 2.5 V — 0.15 50 μA Notes: 1. For more information on VREGIN characteristics, see Table 8.1 on page 74. 2. VIO must be equal to or greater than VDD. 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 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 = 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 interest 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. 34 Rev. 1.2 C8051F410/1/2/3 Table 3.2. Index to Electrical Characteristics Tables Table Title Page # ADC0 Electrical Characteristics (VDD = 2.5 V, VREF = 2.2 V) 61 ADC0 Electrical Characteristics (VDD = 2.1 V, VREF = 1.5 V) 62 IDAC Electrical Characteristics 69 Voltage Reference Electrical Characteristics 72 Voltage Regulator Electrical Specifications 74 Comparator Electrical Characteristics 84 Reset Electrical Characteristics 124 Flash Electrical Characteristics 133 Port I/O DC Electrical Characteristics 151 Oscillator Electrical Characteristics 162 Rev. 1.2 35 C8051F410/1/2/3 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 1 28 I/O Supply Voltage. GND 6 5 Ground. VRTC-BACKUP 3 2 smaRTClock Backup Supply Voltage. VREGIN 8 7 On-Chip Voltage Regulator Input. RSTb/ 2 P2.7/ C2D 27 D I/O Clock signal for the C2 Debug Interface. D I/O Port 2.7. See Port I/O Section for a complete description. D I/O 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/ 17 16 IDAC0 17 IDAC1 P0.3 IDAC0 Output. See IDAC Section for complete description. D I/O or Port 0.1. See Port I/O Section for a complete description. A In 18 P0.2 D I/O or Port 0.0. See Port I/O Section for a complete description. A In A Out P0.1/ 36 Device Reset. Open-drain output of internal POR or VDD monitor. An external source can initiate a system reset by driving this pin low for at least 15 μs. A 1 k pullup to VIO is recommended. See Reset Sources Section for a complete description. 1 C2CK 32 D I/O A Out IDAC1 Output. See IDAC Section for complete description. 19 18 D I/O or Port 0.2. See Port I/O Section for a complete description. A In 20 19 D I/O or Port 0.3. See Port I/O Section for a complete description. A In Rev. 1.2 C8051F410/1/2/3 Table 4.1. Pin Definitions for the C8051F41x (Continued) Name Pin Numbers ‘F410/2 ‘F411/3 P0.4/ Description D I/O or Port 0.4. See Port I/O Section for a complete description. A In 21 20 TX D Out P0.5/ UART TX Pin. See Port I/O Section for a complete description. D I/O or Port 0.5. See Port I/O Section for a complete description. A In 22 21 RX D In P0.6/ UART RX Pin. See Port I/O Section for a complete description. D I/O or Port 0.6. See Port I/O Section for a complete description. A In 23 22 CNVSTR P0.7 Type D In 24 23 D I/O or Port 0.7. See Port I/O Section for a complete description. A In 8 D I/O or Port 1.0. See Port I/O Section for a complete description. A In External Clock Input. This pin is the external oscillator A In return for a crystal or resonator. See Oscillator Section. P1.0/ 9 External Convert Start Input for ADC0, IDA0, and IDA1. See ADC0 or IDACs section for a complete description. XTAL1 Port 1.1. See Port I/O Section for a complete description. D I/O or A In P1.1/ 10 9 A O or D In XTAL2 P1.2 11 10 VREF 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. D I/O or Port 1.2. See Port I/O Section for a complete description. A In A In External VREF Input. See VREF Section. P1.3 12 11 D I/O or Port 1.3. See Port I/O Section for a complete description. A In P1.4 13 12 D I/O or Port 1.4. See Port I/O Section for a complete description. A In P1.5 14 13 D I/O or Port 1.5. See Port I/O Section for a complete description. A In P1.6 15 14 D I/O or Port 1.6. See Port I/O Section for a complete description. A In Rev. 1.2 37 C8051F410/1/2/3 Table 4.1. Pin Definitions for the C8051F41x (Continued) Name Pin Numbers Type Description ‘F410/2 ‘F411/3 P1.7 16 15 D I/O or Port 1.7. See Port I/O Section for a complete description. A In P2.0 25 24 D I/O or Port 2.0. See Port I/O Section for a complete description. A In P2.1 26 25 D I/O or Port 2.1. See Port I/O Section for a complete description. A In P2.2 27 26 D I/O or Port 2.2. See Port I/O Section for a complete description. A In P2.3* 28 D I/O or Port 2.3. See Port I/O Section for a complete description. A In P2.4* 29 D I/O or Port 2.4. See Port I/O Section for a complete description. A In P2.5* 30 D I/O or Port 2.5. See Port I/O Section for a complete description. A In P2.6* 31 D I/O or Port 2.6. See Port I/O Section for a complete description. A In *Note: Available only on the C8051F410/2. 38 Rev. 1.2 C8051F410/1/2/3 Figure 4.1. LQFP-32 Pinout Diagram (Top View) Rev. 1.2 39 C8051F410/1/2/3 Figure 4.2. QFN-28 Pinout Diagram (Top View) 40 Rev. 1.2 C8051F410/1/2/3 Figure 4.3. LQFP-32 Package Diagram Table 4.2. LQFP-32 Package Dimensions A A1 A2 b c D D1 e E E1 L MM TYP — — 1.40 0.37 — 9.00 7.00 0.80 9.00 7.00 0.60 MIN — 0.05 1.35 0.30 0.09 — — — — — 0.45 Rev. 1.2 MAX 1.60 0.15 1.45 0.45 0.20 — — — — — 0.75 41 C8051F410/1/2/3 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 E 42 0.80 BSC X1 0.40 0.50 Y1 1.25 1.35 Rev. 1.2 C8051F410/1/2/3 Figure 4.5. QFN-28 Package Drawing Table 4.4. QFN-28 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A A1 A3 b D D2 e E E2 0.80 0.00 0.90 0.02 0.25 REF 0.23 5.00 BSC. 3.15 0.50 BSC. 5.00 BSC. 3.15 1.00 0.05 L L1 aaa bbb ddd eee Z Y 0.35 0.00 0.55 — 0.15 0.10 0.05 0.08 0.44 0.18 0.65 0.15 0.18 2.90 2.90 0.30 3.35 3.35 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation VHHD except for custom features D2, E2, Z, Y, and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small Body Components. Rev. 1.2 43 C8051F410/1/2/3 Figure 4.6. QFN-28 Recommended PCB Land Pattern Table 4.5. QFN-28 PCB Land Pattern Dimensions Dimension C1 C2 E X1 Min Max Dimension Min Max X2 Y1 Y2 3.20 0.85 3.20 3.30 0.95 3.30 4.80 4.80 0.50 0.20 0.30 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification. 3. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60m minimum, all the way around the pad. Stencil Design 5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 6. The stencil thickness should be 0.125mm (5 mils). 7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins. 8. A 3x3 array of 0.90mm openings on a 1.1mm pitch should be used for the center pad to assure the proper paste volume (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. 44 Rev. 1.2 C8051F410/1/2/3 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 automatically enable ADC0, capture and accumulate samples, then place ADC0 in a low power shutdown mode without CPU intervention. The AMUX0, data conversion modes, and window detector 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 output, 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 shutdown when AD0EN is logic 0 and no Burst Mode conversions are taking place. Figure 5.1. ADC0 Functional Block Diagram 5.1. Analog Multiplexer AMUX0 selects the input channel 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 configured 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 Section “18. Port Input/Output” on page 135 for more Port I/O configuration details. Rev. 1.2 45 C8051F410/1/2/3 5.2. Temperature Sensor The typical temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the positive ADC input when the temperature sensor is selected by bits AD0MX4-0 in register ADC0MX. Figure 5.2. Typical Temperature Sensor Transfer Function 5.3. ADC0 Operation In a typical system, ADC0 is configured using the following steps: Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. Step 8. 46 Choose the start of conversion source. Choose Normal Mode or Burst Mode operation. If Burst Mode, choose the ADC0 Idle Power State and set the Power-Up Time. Choose the tracking mode. Note that Pre-Tracking Mode can only be used with Normal Mode. Calculate required settling time and set the post convert-start tracking time using the AD0TK bits. Choose the repeat count. Choose the output word justification (Right-Justified or Left-Justified). Enable or disable the End of Conversion and Window Comparator Interrupts. Rev. 1.2 C8051F410/1/2/3 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 following: • • • • Writing a ‘1’ to the 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 "ondemand.” During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. See Section “24. Timers” on page 216 for timer configuration. Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port Pin P0.6. When the CNVSTR input is used as the ADC0 conversion source, Port Pin P0.6 should be skipped by the Digital Crossbar. To configure the Crossbar to skip P0.6, set bit 6 in the P0SKIP register to logic 1. See Section “18. Port Input/Output” on page 135 for details on Port I/O configuration. 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 maximizes tracking time by tracking before and after the convert start signal. Figure 5.3 shows examples of the three tracking modes. Pre-Tracking Mode is selected when AD0TM 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 between each end of conversion and the next convert start 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 programmed 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 programmed tracking time ends. After a conversion is complete, ADC0 tracks continuously until the next conversion is started. Rev. 1.2 47 C8051F410/1/2/3 Depending on the output connected to the ADC input, additional tracking time, more than is specified in Table 5.3 and Table 5.4, may be required after changing MUX settings. See the settling time requirements described in Section “5.3.6. Settling Time Requirements” on page 52. 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 three states at any given time: 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 followed 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. 48 Rev. 1.2 C8051F410/1/2/3 Figure 5.4. 12-Bit ADC Tracking Mode Example Rev. 1.2 49 C8051F410/1/2/3 5.3.4. Burst Mode Burst Mode is a power saving feature that allows ADC0 to remain in a low power state between conversions. When Burst Mode is enabled, ADC0 wakes from a low power state, accumulates 1, 4, 8, or 16 samples 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 down after each burst. If AD0EN is set to logic 1, ADC0 remains enabled after each burst. On each convert start signal, ADC0 is awakened from its Idle Power State. If ADC0 is powered down, it will automatically power up and wait the programmable Power-Up Time controlled by the AD0PWR bits. Otherwise, ADC0 will start tracking and converting immediately. Figure 5.5 shows an example of Burst Mode Operation with a slow system clock and a repeat count of 4. Important Note: When Burst Mode is enabled, only Post-Tracking and Dual-Tracking modes can be used. When Burst Mode is enabled, a single convert start will initiate a number of conversions equal to the repeat 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 Mode, care must be taken to issue a convert start signal no faster than once every four SYSCLK periods. This includes external convert start signals. Figure 5.5. 12-Bit ADC Burst Mode Example with Repeat Count Set to 4 50 Rev. 1.2 C8051F410/1/2/3 5.3.5. Output Conversion Code The registers ADC0H and ADC0L contain the high and low bytes of the output conversion code. When the repeat count is set to 1, conversion codes are represented in 12-bit unsigned integer format and the output 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. Table 5.1. ADC0 Examples of Right- and Left-Justified Samples Input Voltage VREF x 4095/4096 VREF x 2048/4096 VREF x 2047/4096 0 Right-Justified ADC0H:ADC0L (AD0LJST = 0) 0x0FFF 0x0800 0x07FF 0x0000 Left-Justified ADC0H:ADC0L (AD0LJST = 1) 0xFFF0 0x8000 0x7FF0 0x0000 When the ADC0 Repeat Count is greater than 1, the output conversion code represents the accumulated result of the conversions performed and is updated after the last conversion in the series is finished. Sets of 4, 8, or 16 consecutive samples can be accumulated and represented in unsigned integer format. The repeat count can be selected using the AD0RPT bits in the ADC0CF register. The value must be rightjustified (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 5.2. ADC0 Repeat Count Examples at Various Input Voltages Input Voltage VREF x 4095/4096 VREF x 2048/4096 VREF x 2047/4096 0 Repeat Count = 4 0x3FFC 0x2000 0x1FFC 0x0000 Repeat Count = 8 0x7FF8 0x4000 0x3FF8 0x0000 Rev. 1.2 Repeat Count = 16 0xFFF0 0x8000 0x7FF0 0x0000 51 C8051F410/1/2/3 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. n 2 t = ln  -------  R TOTAL C SAMPLE  SA 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). k Figure 5.6. ADC0 Equivalent Input Circuits 52 Rev. 1.2 C8051F410/1/2/3 SFR Definition 5.1. ADC0MX: ADC0 Channel Select R R R - - - Bit7 Bit6 Bit5 R/W R/W Bit4 Bit3 R/W R/W R/W Reset Value Bit1 Bit0 SFR Address: AD0MX Bit2 00011111 0xBB Bits7–5: UNUSED. Read = 000b; Write = don’t care. Bits4–0: AD0MX4–0: AMUX0 Positive Input Selection AD0MX4–0 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 - 11111 ADC0 Input Channel P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3* P2.4* P2.5* P2.6* P2.7 Temp Sensor VDD GND *Note: Only applies to C8051F410/2; selection RESERVED on C8051F411/3 devices. Rev. 1.2 53 C8051F410/1/2/3 SFR Definition 5.2. ADC0CF: ADC0 Configuration R/W R/W Bit7 Bit6 R/W R/W R/W R/W Bit4 Bit3 Bit2 AD0SC Bit5 R/W AD0RPT Bit1 R/W Reset Value Reserved 11111000 Bit0 SFR Address: 0xBC Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from FCLK by the following equation, where 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. FCLK AD0SC = --------------------- – 1 * CLK SAR FCLK CLK SAR = ----------------------------AD0SC + 1 or *Note: Round the result up. Bits2–1: AD0RPT1–0: ADC0 Repeat Count. Controls the number of conversions taken and accumulated between ADC0 End of Conversion (ADCINT) and ADC0 Window Comparator (ADCWINT) interrupts. A convert start is required for each conversion 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: Bit0: 54 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. RESERVED. Read = 0b; Must write 0b. Rev. 1.2 C8051F410/1/2/3 SFR Definition 5.3. ADC0H: ADC0 Data Word MSB R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xBE 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 bits of the ADC0 12-bit result. SFR Definition 5.4. ADC0L: ADC0 Data Word LSB 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 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. Rev. 1.2 55 C8051F410/1/2/3 SFR Definition 5.5. ADC0CN: ADC0 Control R/W R/W R/W R/W R/W R/W R/W R/W AD0EN BURSTEN AD0INT AD0BUSY AD0WINT AD0LJST AD0CM1 AD0CM0 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 (bit addressable) Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bits1-0: 56 Reset Value 00000000 SFR Address: 0xE8 AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. BURSTEN: ADC0 Burst Mode Enable Bit. 0: ADC0 Burst Mode Disabled. 1: ADC0 Burst Mode Enabled. AD0INT: ADC0 Conversion Complete Interrupt Flag. 0: ADC0 has not completed a data conversion since the last time AD0INT was cleared. 1: ADC0 has completed a data conversion. AD0BUSY: ADC0 Busy Bit. Read: 0: ADC0 conversion is complete or a conversion 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 AD0WINT: ADC0 Window Compare Interrupt Flag. 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. 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 greater than 1 (when AD0RPT1-0 is 01b, 10b, or 11b). AD0CM1-0: ADC0 Start of Conversion Mode Select. 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. Rev. 1.2 C8051F410/1/2/3 SFR Definition 5.6. ADC0TK: ADC0 Tracking Mode Select R/W R/W Bit7 Bit6 R/W R/W R/W Bit4 Bit3 AD0PWR Bit5 R/W R/W Bit2 Bit1 AD0TM R/W Reset Value Bit0 SFR Address: AD0TK 11111111 (bit addressable) 0xBA 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 start signal. The Power Up time is programmed according to the following equation: Tstartup AD0PWR = ---------------------- – 1 400ns or Tstartup =  AD0PWR + 1 400ns 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. 5.4. Programmable Window Detector The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-programmed limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL) registers hold the comparison values. The window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0 Less-Than and ADC0 Greater-Than registers. Rev. 1.2 57 C8051F410/1/2/3 SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xC4 Bits7–0: High byte of ADC0 Greater-Than Data Word. SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xC3 Bits7–0: Low byte of ADC0 Greater-Than Data Word. 58 Rev. 1.2 C8051F410/1/2/3 SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC6 Bits7–0: High byte of ADC0 Less-Than Data Word. SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xC5 Bits7–0: Low byte of ADC0 Less-Than Data Word. Rev. 1.2 59 C8051F410/1/2/3 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 example 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 60 Rev. 1.2 C8051F410/1/2/3 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 kHz sine-wave Single-ended input, 0 to 1 dB below Full Scale, 200 ksps) Regular Mode (BURSTEN = '0') 66 69 — Signal-to-Noise Plus Distortion dB Burst Mode (BURSTEN = '1') 60 63 — Total Harmonic Distortion Up to the 5th harmonic — –77 — dB — –94 — dB — — 3 MHz Conversion Time in SAR Clocks1 — 13 — clocks Track/Hold Acquisition Time2 Throughput Rate Analog Inputs 1 — — μs — — 200 ksps Input Voltage Range 0 — VREF V Input Capacitance Temperature Sensor — 12 — pF Linearity3,4 — ±0.2 — °C Slope4 — 2.95 — mV/°C Slope Error3 — ±73 — μV/°C — 900 — mV — ±17 — mV 12 — — μs — 680 1000 μA — — 100 1 — — μA mV/V Spurious-Free Dynamic Range Conversion Rate SAR Conversion Clock Offset4 Offset Regular Mode (BURSTEN = '0') (Temp = 0 °C) Error3 Tracking Time Power Specifications Power Supply Current (VDD supplied to ADC0) Operating Mode, 200 ksps Burst Mode (Idle) Power Supply Rejection 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 input. See Section “5.3.6. Settling Time Requirements” on page 52. 3. Represents one standard deviation from the mean. 4. Includes ADC offset, gain, and linearity variations. Rev. 1.2 61 C8051F410/1/2/3 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 kHz sine-wave Single-ended input, 0 to 1 dB below Full Scale, 200 ksps) Regular Mode (BURSTEN = '0') 66 68 — Signal-to-Noise Plus Distortion dB Burst Mode (BURSTEN = '1') 60 62 — Total Harmonic Distortion Up to the 5th harmonic — –75 — dB — –90 — dB — — 3 MHz Conversion Time in SAR Clocks1 — 13 — clocks Track/Hold Acquisition Time2 Throughput Rate Analog Inputs 1 — — μs — — 200 ksps Input Voltage Range 0 — VREF V Input Capacitance Temperature Sensor — 12 — pF Linearity3,4 — ±0.2 — °C Slope4 — 2.95 — mV/°C Slope Error3 Offset — ±73 — μV/°C — 900 — mV — ±17 — mV 12 — — μs — 650 1000 μA — — 100 1 — — μA mV/V Spurious-Free Dynamic Range Conversion Rate SAR Conversion Clock Regular Mode (BURSTEN = '0') (Temp = 0 °C) Offset Error3 Tracking Time Power Specifications Power Supply Current (VDD supOperating Mode, 200 ksps plied to ADC0) Burst Mode (Idle) Power Supply Rejection 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 input. See Section “5.3.6. Settling Time Requirements” on page 52. 3. Represents one standard deviation from the mean. 4. Includes ADC offset, gain, and linearity variations. 62 Rev. 1.2 C8051F410/1/2/3 6. 12-Bit Current Mode DACs (IDA0 and IDA1) The C8051F41x devices include two 12-bit current-mode Digital-to-Analog Converters (IDACs). The maximum 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 corresponding IDAC Control Register (IDA0CN or IDA1CN). When both IDACs are enabled, their outputs may be routed to individual pins or merged onto a single pin. An internal bandgap bias generator is used to generate a reference current for the IDACs whenever they are enabled. IDAC updates can be performed ondemand, 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 effect on the IDAn output until a write to IDAnH takes place. Since data from both the high and low bytes of the data register are immediately latched to IDAn after 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 (typically 0x00), and writing data only to IDA0H. Rev. 1.2 63 C8051F410/1/2/3 6.1.2. Update Output Based on Timer Overflow The IDAC output update can be scheduled on a Timer 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’, ‘010’ or ‘011’, writes to both IDAC data registers (IDAnL and IDAnH) 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, allowing the IDAC output 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 word (D11-D4) are mapped to bits 7-0 of the IDAnH register and the 4 LSBs of the data 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 configured to provide full-scale output currents of 0.25 mA, 0.5 mA, or 1 mA. Left Justified Data (IDAnRJST = 0): IDAnH D11 D10 D9 D8 D7 D6 IDAnL D5 D4 D3 D2 D1 D0 D9 D8 D7 D6 D5 D4 Right Justified Data (IDAnRJST = 1): IDAnH D11 D10 IDAnL D3 D2 D1 D0 IDAn Data Word Output Current vs IDAnOMD bit setting (D11–D0) ‘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 4095/4096 x 1 mA 4095/4096 x 0.5 mA 4095/4096 x 0.25 mA Figure 6.2. IDAC Data Word Mapping 64 Rev. 1.2 C8051F410/1/2/3 SFR Definition 6.1. IDA0CN: IDA0 Control R/W R/W IDA0EN Bit7 R/W R/W R/W R - IDA0RJST Bit4 Bit3 Bit2 IDA0CM Bit6 Bit5 R/W R/W IDA0OMD Bit1 Reset Value 01110011 Bit0 SFR Address: 0xB9 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. SFR Definition 6.2. IDA0H: IDA0 Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x97 Bits 7–0: IDA0 Data 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. Rev. 1.2 65 C8051F410/1/2/3 SFR Definition 6.3. IDA0L: IDA0 Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0x96 Bits 7–0: IDA0 Data 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. SFR Definition 6.4. IDA1CN: IDA1 Control R/W R/W IDA1EN Bit7 R/W R/W R/W R - IDA1RJST Bit4 Bit3 Bit2 IDA1CM Bit6 Bit5 R/W R/W IDA1OMD Bit1 Reset Value 01110011 Bit0 SFR Address: 0xB5 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. 66 Rev. 1.2 C8051F410/1/2/3 SFR Definition 6.5. IDA1H: IDA0 Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xF5 Bits 7–0: IDA1 Data 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. SFR Definition 6.6. IDA1L: IDA1 Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xF4 Bits 7–0: IDA1 Data 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. 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 automatically disabled, and the pin 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. Rev. 1.2 67 C8051F410/1/2/3 Figure 6.3. IDAC Pin Connections 68 Rev. 1.2 C8051F410/1/2/3 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 Integral Nonlinearity bits — — ±10 LSB Differential Nonlinearity Guaranteed Monotonic — — ±1 LSB Output Compliance Range Guaranteed by Design, Applies to entire VDD range — — VDD – 1.2 V — 0 — LSB — 0.05 2 % Gain-Error Tempco — 320 — nA/°C VDD Power Supply Rejection Ratio — 2 — μA/V Output Capacitance — 2 — pF — 10 — μs — 0.5 0.5 0.5 — % % % — 2.1 1.1 0.6 0.35 — mA mA mA mA Offset Error Gain Error 2 mA Full Scale Output Current Dynamic Performance Startup Time Gain Variation From 2 mA range 1 mA Full Scale Output Current 0.5 mA Full Scale Output Current 0.25 mA Full Scale Output Current 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 Rev. 1.2 69 C8051F410/1/2/3 7. Voltage Reference The Voltage reference MUX on C8051F41x devices is configurable to use an externally connected voltage 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 generator 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 bias generator, which is used by the ADC, Temperature Sensor, internal oscillators, and IDACs. This bit is forced to logic 1 when any of the aforementioned peripherals 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 Diagram 70 Rev. 1.2 C8051F410/1/2/3 Important Note About the VREF Pin: Port pin P1.2 is used as the external VREF input and as an 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 analog 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 135 for complete Port I/O configuration details. The TEMPE bit in register REF0CN enables/disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in meaningless data. SFR Definition 7.1. REF0CN: Reference Control 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 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: IDAMRG: IDAC Output Merge Select. 0: IDA1 Output is P0.1. 1: IDA1 Output is P0.0 (Merged with IDA0 Output). GF. General Purpose Flag. This bit is a general purpose flag for use under software control. ZTCEN: Zero-TempCo Bias Enable Bit. 0: ZeroTC Bias Generator automatically enabled when needed. 1: ZeroTC Bias Generator forced on. 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. 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. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor off. 1: Internal Temperature Sensor on. BIASE: Internal Analog Bias Generator Enable Bit. 0: Internal Analog Bias Generator automatically enabled when needed. 1: Internal Analog Bias Generator on. REFBE: Internal Reference Buffer Enable Bit. 0: Internal Reference Buffer disabled. 1: Internal Reference Buffer enabled. Internal voltage reference driven on the VREF pin. Rev. 1.2 71 C8051F410/1/2/3 Table 7.1. Voltage Reference Electrical Characteristics VDD = 2.0 V; –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units 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 Coefficient — 35 — ppm/°C — 10 — ppm/μA — — 2.5 55 — — ms μs — — 6.8 144 — — ms μs — 2 — mV/V 0 — VDD V Sample Rate = 200 ksps; VREF = 2 V — 5 — μA BIASE = ‘1’ — 22 — μA — 50 — μA Internal Reference (REFBE = 1) Output Voltage Load Regulation Load = 0 to 200 μA to GND 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 Power Supply Rejection External Reference (REFBE = 0) Input Voltage Range Input Current Bias Generators ADC Bias Generator Power Consumption (Internal) 72 Rev. 1.2 C8051F410/1/2/3 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. When enabled, the output of REG0 appears on the 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 capacitor (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 voltage 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 Rev. 1.2 73 C8051F410/1/2/3 SFR Definition 8.1. REG0CN: Regulator Control R/W R/W REGDIS Reserved Bit7 Bit6 R R/W R R R — REG0MD — — — Bit5 Bit4 Bit3 Bit2 Bit1 R Reset Value DROPOUT 00010000 Bit0 SFR Address: 0xC9 Bit 7: REGDIS: Voltage Regulator Disable Bit. This bit disables/enables the Voltage 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 dropout. 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 (See Note) — 5.25 V Load Current — — 50 mA Load Regulation — 7 15 mV/mA 2.0 2.35 2.1 2.5 2.25 2.55 V — — 1 1 1.5 1.5 μA Dropout Indicator Detection Threshold — 65 — mV Output Voltage Tempco — 600 — μV/ºC — 250 — μs Input Voltage Range (VREGIN)* Output Voltage (VDD) Output Current = 1 mA REG0MD = ‘0’ REG0MD = ‘1’ Bias Current REG0MD = ‘0’ REG0MD = ‘1’ VREG Settling Time 50 mA load with VREGIN = 2.5 V and VDD load capacitor of 4.8 μF *Note: VDD = VREGIN – (Load Regulation x Load Current). 74 Rev. 1.2 C8051F410/1/2/3 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 Comparator0 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 configured as open drain or push-pull (see Section “18.2. Port I/O Initialization” on page 139). Comparator0 may also be used as a reset source (see Section “15.5. Comparator0 Reset” on page 122). The Comparator0 inputs are selected in the CPT0MX 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 CMX1P3CMX1P0 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 configured as analog inputs in their associated Port configuration register (with a ‘1’ written to the corresponding Port Latch register), and configured to be skipped by the Crossbar (for details on Port configuration, see Section “18.3. General Purpose Port I/O” on page 142) Figure 9.1. Comparator0 Functional Block Diagram Rev. 1.2 75 C8051F410/1/2/3 The Comparator output can be polled in software, used as an interrupt source, internal oscillator suspend awakening source and/or routed to a Port pin. When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system clock; the asynchronous output is available even in STOP 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 Decoder” on page 137 for details 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 registers (see SFR Definition 9.3 and SFR Definition 9.5). Selecting a longer response time reduces the Comparator supply current. See Table 9.1 for complete timing and current consumption specifications. Figure 9.2. Comparator1 Functional Block Diagram 76 Rev. 1.2 C8051F410/1/2/3 Figure 9.3. Comparator Hysteresis Plot The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN (for n = 0 or 1). The user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going symmetry of this hysteresis around the threshold voltage. The Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN (shown in SFR Definition 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. Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “12. Interrupt Handler” on page 102). 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 Comparator 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 Comparator 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 from SUSPEND mode if the Comparator 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 84. Rev. 1.2 77 C8051F410/1/2/3 SFR Definition 9.1. CPT0CN: Comparator0 Control R/W R R/W CP0EN CP0OUT CP0RIF Bit7 Bit6 Bit5 R/W R/W R/W R/W R/W Reset Value CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x9B Bit7: CP0EN: Comparator0 Enable Bit. 0: Comparator0 Disabled. 1: Comparator0 Enabled. Bit6: CP0OUT: Comparator0 Output State Flag. 0: Voltage on CP0+ < CP0–. 1: Voltage on CP0+ > CP0–. Bit5: CP0RIF: Comparator0 Rising-Edge Flag. 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 Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. 78 Rev. 1.2 C8051F410/1/2/3 SFR Definition 9.2. CPT0MX: Comparator0 MUX Selection R/W R/W R/W R/W R/W R/W R/W R/W CMX0N3 CMX0N2 CMX0N1 CMX0N0 CMX0P3 CMX0P2 CMX0P1 CMX0P0 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0x9F Bits7–4: CMX0N3–CMX0N0: Comparator0 Negative Input MUX Select. These bits select which Port pin is used as the Comparator0 negative input. CMX0N3 CMX0N2 CMX0N1 CMX0N0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 x x Negative Input P0.1 P0.3 P0.5 P0.7 P1.1 P1.3 P1.5 P1.7 P2.1 P2.3* P2.5* P2.7 Reserved *Note: Available only on the C8051F410/2. Bits1–0: CMX0P3–CMX0P0: Comparator0 Positive Input MUX Select. These bits select which Port pin is used as the Comparator0 positive input. CMX0P3 CMX0P2 CMX0P1 CMX0P0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 x x Positive Input P0.0 P0.2 P0.4 P0.6 P1.0 P1.2 P1.4 P1.6 P2.0 P2.2 P2.4* P2.6* Reserved *Note: Available only on the C8051F410/2. Rev. 1.2 79 C8051F410/1/2/3 SFR Definition 9.3. CPT0MD: Comparator0 Mode Selection R/W R/W R/W R/W R/W R/W RESERVED - CP0RIE CP0FIE - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 R/W R/W Reset Value CP0MD1 CP0MD0 00000010 Bit1 Bit0 SFR Address: 0x9D Bit7: Bit6: Bit5: RESERVED. Read = 0b. Must Write 0b. UNUSED. Read = 0b. Write = don’t care. CP0RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled. 1: Comparator rising-edge interrupt enabled. Bit4: CP0FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator 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 Comparator0. Mode 0 1 2 3 80 CP0MD1 0 0 1 1 CP0MD0 0 1 0 1 Effect Fastest Response Time — — Lowest Power Consumption Rev. 1.2 C8051F410/1/2/3 SFR Definition 9.4. CPT1MX: Comparator1 MUX Selection R/W R/W R/W R/W R/W R/W R/W R/W CMX1N3 CMX1N2 CMX1N1 CMX1N0 CMX1P3 CMX1P2 CMX1P1 CMX1P0 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0x9E Bits7–4: CMX1N3–CMX1N0: Comparator1 Negative Input MUX Select. These bits select which Port pin is used as the Comparator1 negative input. CMX1N3 CMX1N2 CMX1N1 CMX1N0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 x x Negative Input P0.1 P0.3 P0.5 P0.7 P1.1 P1.3 P1.5 P1.7 P2.1 P2.3* P2.5* P2.7 Reserved *Note: Available only on the C8051F410/2. Bits3–0: CMX1P3–CMX1P0: Comparator1 Positive Input MUX Select. These bits select which Port pin is used as the Comparator1 positive input. CMX1P3 CMX1P2 CMX1P1 CMX1P0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 x x Positive Input P0.0 P0.2 P0.4 P0.6 P1.0 P1.2 P1.4 P1.6 P2.0 P2.2 P2.4* P2.6* Reserved *Note: Available only on the C8051F410/2. Rev. 1.2 81 C8051F410/1/2/3 SFR Definition 9.5. CPT1MD: Comparator1 Mode Selection R/W R/W R/W R/W R/W R/W RESERVED - CP1RIE CP1FIE - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 R/W R/W Reset Value CP1MD1 CP1MD0 00000010 Bit1 Bit0 SFR Address: 0x9C Bit7: Bit6: Bit5: RESERVED. Read = 0b. Must Write 0b. UNUSED. Read = 0b. Write = don’t care. CP1RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled. 1: Comparator rising-edge interrupt enabled. Bit4: CP1FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator 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 Comparator1. Mode 0 1 2 3 82 CP1MD1 0 0 1 1 CP1MD0 0 1 0 1 Effect Fastest Response Time — — Lowest Power Consumption Rev. 1.2 C8051F410/1/2/3 SFR Definition 9.6. CPT1CN: Comparator1 Control R/W R R/W CP1EN CP1OUT CP1RIF Bit7 Bit6 Bit5 R/W R/W R/W R/W R/W Reset Value CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x9A Bit7: CP1EN: Comparator1 Enable Bit. 0: Comparator1 Disabled. 1: Comparator1 Enabled. Bit6: CP1OUT: Comparator1 Output State Flag. 0: Voltage on CP1+ < CP1-. 1: Voltage on CP1+ > CP1-. Bit5: CP1RIF: Comparator1 Rising-Edge Flag. 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 Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. Rev. 1.2 83 C8051F410/1/2/3 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 Response Time: Mode 0, Vcm1 = 1.5 V Response Time: Mode 1, Vcm1 = 1.5 V Response Time: Mode 2, Vcm1 = 1.5 V Response Time: Mode 3, Vcm1 = 1.5 V Conditions Min Typ Max Units CP0+ – CP0– = 100 mV — 120 — ns CP0+ – CP0– = –100 mV — 160 — ns CP0+ – CP0– = 100 mV — 200 — ns CP0+ – CP0– = –100 mV — 340 — ns CP0+ – CP0– = 100 mV — 360 — ns CP0+ – CP0– = –100 mV — 720 — ns CP0+ – CP0– = 100 mV — 2.2 — μs CP0+ – CP0– = –100 mV — 7.2 — μs — 1.5 14 mV/V Common-Mode Rejection Ratio2 Positive Hysteresis 1 CP0HYP1-0 = 00 — 0.5 2.0 mV Positive Hysteresis 2 CP0HYP1-0 = 01 2 4.5 10 mV Positive Hysteresis 3 CP0HYP1-0 = 10 5 9.0 20 mV Positive Hysteresis 4 CP0HYP1-0 = 11 13 18.0 40 mV Negative Hysteresis 1 CP0HYN1-0 = 00 — –0.5 –2.0 mV Negative Hysteresis 2 CP0HYN1-0 = 01 –2 –4.5 –10 mV Negative Hysteresis 3 CP0HYN1-0 = 10 –5 –9.0 –20 mV Negative Hysteresis 4 CP0HYN1-0 = 11 –13 –18.0 –40 mV –0.25 — VDD + 0.25 V Input Capacitance — 4 — pF Input Bias Current — 0.5 — nA –10 — 10 mV Power Supply Rejection2 — 0.2 4 mV/V Power-up Time — 2.3 — μs Mode 0 — 13 30 μA Mode 1 — 6.0 20 μA Mode 2 — 3.0 10 μA Mode 3 — 1.0 5 μA Inverting or Non-Inverting Input Voltage Range Input Offset Voltage Power Supply Supply Current at DC Notes: 1. Vcm is the common-mode voltage on CP0+ and CP0–. 2. Guaranteed by design and/or characterization. 84 Rev. 1.2 C8051F410/1/2/3 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 software. The C8051F41x family has a superset of all the peripherals included with a standard 8051. See Section “1. System Overview” on page 15 for more information about the available peripherals. The CIP-51 includes on-chip debug hardware which interfaces directly with the analog and digital subsystems, providing a complete data acquisition or control-system solution in a single integrated circuit. The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as additional custom peripherals and functions to extend its capability (see Figure 10.1 for a block diagram). The CIP-51 core includes the following features: - 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 Figure 10.1. CIP-51 Block Diagram Rev. 1.2 85 C8051F410/1/2/3 Performance The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 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 running at 50 MHz, it has a peak throughput of 50 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute 1 2 2/4 3 3/5 4 5 4/6 6 8 Number of Instructions 26 50 5 10 7 5 2 1 2 1 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 allows program memory to be used for non-volatile data storage as well as updating program code under software control. The on-chip debug support 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 memory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or other on-chip resources. The CIP-51 is supported by development tools from Silicon Laboratories, Inc. and third party vendors. Silicon Laboratories provides an integrated development environment (IDE) including editor, evaluation compiler, 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™ instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51 instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes, addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051. 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 taken as opposed to when the branch is taken. 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. 86 Rev. 1.2 C8051F410/1/2/3 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 instruction can also be used to write or erase on-chip program memory space implemented as reprogrammable 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 125 for further details. Table 10.1. CIP-51 Instruction Set Summary1 Mnemonic ADD A, Rn ADD A, direct ADD A, @Ri ADD A, #data ADDC A, Rn ADDC A, direct ADDC A, @Ri ADDC A, #data SUBB A, Rn SUBB A, direct SUBB A, @Ri SUBB A, #data INC A INC Rn INC direct INC @Ri DEC A DEC Rn DEC direct DEC @Ri INC DPTR MUL AB DIV AB DA A ANL A, Rn ANL A, direct ANL A, @Ri ANL A, #data ANL direct, A ANL direct, #data ORL A, Rn Description Arithmetic Operations Add register to A Add direct byte to A Add indirect RAM to A Add immediate to A Add register to A with carry Add direct byte to A with carry Add indirect RAM to A with carry Add immediate to A with carry Subtract register from A with borrow Subtract direct byte from A with borrow Subtract indirect RAM from A with borrow Subtract immediate from A with borrow Increment A Increment register Increment direct byte Increment indirect RAM Decrement A Decrement register Decrement direct byte Decrement indirect RAM Increment Data Pointer Multiply A and B Divide A by B Decimal adjust A Logical Operations AND Register to A AND direct byte to A AND indirect RAM to A AND immediate to A AND A to direct byte AND immediate to direct byte OR Register to A Bytes Clock Cycles 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 1 1 2 1 1 1 1 1 1 2 2 2 1 2 2 2 1 2 2 2 1 1 2 2 1 1 2 2 1 4 8 1 1 2 1 2 2 3 1 1 2 2 2 2 3 1 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). Rev. 1.2 87 C8051F410/1/2/3 Table 10.1. CIP-51 Instruction Set Summary1 (Continued) Mnemonic ORL A, direct ORL A, @Ri ORL A, #data ORL direct, A ORL direct, #data XRL A, Rn XRL A, direct XRL A, @Ri XRL A, #data XRL direct, A XRL direct, #data CLR A CPL A RL A RLC A RR A RRC A SWAP A Description Bytes Clock Cycles 2 2 2 2 3 1 2 2 2 2 3 1 1 1 1 1 1 1 2 1 2 2 3 1 2 1 2 2 3 1 1 1 1 1 1 1 MOV A, Rn MOV A, direct MOV A, @Ri MOV A, #data MOV Rn, A MOV Rn, direct MOV Rn, #data MOV direct, A MOV direct, Rn MOV direct, direct MOV direct, @Ri MOV direct, #data MOV @Ri, A MOV @Ri, direct MOV @Ri, #data MOV DPTR, #data16 MOVC A, @A+DPTR OR direct byte to A OR indirect RAM to A OR immediate to A OR A to direct byte OR immediate to direct byte Exclusive-OR Register to A Exclusive-OR direct byte to A Exclusive-OR indirect RAM to A Exclusive-OR immediate to A Exclusive-OR A to direct byte Exclusive-OR immediate to direct byte Clear A Complement A Rotate A left Rotate A left through Carry Rotate A right Rotate A right through Carry Swap nibbles of A Data Transfer Move Register to A Move direct byte to A Move indirect RAM to A Move immediate to A Move A to Register Move direct byte to Register Move immediate to Register Move A to direct byte Move Register to direct byte Move direct byte to direct byte Move indirect RAM to direct byte Move immediate to direct byte Move A to indirect RAM Move direct byte to indirect RAM Move immediate to indirect RAM Load DPTR with 16-bit constant Move code byte relative DPTR to A 1 2 1 2 1 2 2 2 2 3 2 3 1 2 2 3 1 4 to 72 MOVC A, @A+PC MOVX A, @Ri MOVX @Ri, A MOVX A, @DPTR Move code byte relative PC to A Move external data (8-bit address) to A Move A to external data (8-bit address) Move external data (16-bit address) to A 1 1 1 1 4 to 72 3 3 3 1 2 2 2 1 2 2 2 2 3 2 3 2 2 2 3 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). 88 Rev. 1.2 C8051F410/1/2/3 Table 10.1. CIP-51 Instruction Set Summary1 (Continued) Mnemonic MOVX @DPTR, A PUSH direct POP direct XCH A, Rn XCH A, direct XCH A, @Ri XCHD A, @Ri CLR C CLR bit SETB C SETB bit CPL C CPL bit ANL C, bit ANL C, /bit ORL C, bit ORL C, /bit MOV C, bit MOV bit, C JC rel JNC rel JB bit, rel JNB bit, rel JBC bit, rel ACALL addr11 LCALL addr16 RET RETI AJMP addr11 LJMP addr16 SJMP rel JMP @A+DPTR JZ rel JNZ rel CJNE A, direct, rel CJNE A, #data, rel CJNE Rn, #data, rel CJNE @Ri, #data, rel DJNZ Rn, rel Description Bytes Move A to external data (16-bit address) Push direct byte onto stack Pop direct byte from stack Exchange Register with A Exchange direct byte with A Exchange indirect RAM with A Exchange low nibble of indirect RAM with A Boolean Manipulation Clear Carry Clear direct bit Set Carry Set direct bit Complement Carry Complement direct bit AND direct bit to Carry AND complement of direct bit to Carry OR direct bit to carry OR complement of direct bit to Carry Move direct bit to Carry Move Carry to direct bit Jump if Carry is set Jump if Carry is not set Jump if direct bit is set Jump if direct bit is not set Jump if direct bit is set and clear bit Program Branching Absolute subroutine call Long subroutine call Return from subroutine Return from interrupt Absolute jump Long jump Short jump (relative address) Jump indirect relative to DPTR Jump if A equals zero Jump if A does not equal zero Compare direct byte to A and jump if not equal Compare immediate to A and jump if not equal Compare immediate to Register and jump if not equal Compare immediate to indirect and jump if not equal Decrement Register and jump if not zero 1 2 2 1 2 1 1 Clock Cycles 3 2 2 1 2 2 2 1 2 1 2 1 2 2 2 2 2 2 2 2 2 3 3 3 1 2 1 2 1 2 2 2 2 2 2 2 2/4 2/4 3/5 3/5 3/5 2 3 1 1 2 3 2 1 2 2 3 3 3 3 2 4 5 6 6 4 5 4 4 2/4 2/4 3/5 3/5 3/5 4/6 2/4 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). Rev. 1.2 89 C8051F410/1/2/3 Table 10.1. CIP-51 Instruction Set Summary1 (Continued) Mnemonic DJNZ direct, rel NOP Description Decrement direct byte and jump if not zero No operation Bytes 3 1 Clock Cycles 3/5 1 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). Notes on Registers, Operands and Addressing Modes: Rn - Register R0-R7 of the currently selected register bank. @Ri - Data RAM location addressed indirectly through R0 or R1. rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by SJMP and all conditional jumps. direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location (0x000x7F) 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 LCALL 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. 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 descriptions of the remaining SFRs are included in the sections of the datasheet associated with their corresponding system function. SFR Definition 10.1. SP: Stack Pointer 90 Rev. 1.2 C8051F410/1/2/3 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 Bits7–0: SP: Stack Pointer. The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented before every PUSH operation. The SP register defaults to 0x07 after reset. SFR Definition 10.2. DPL: Data Pointer Low Byte R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 R/W Reset Value 00000000 Bit0 SFR Address: 0x82 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. SFR Definition 10.3. DPH: Data Pointer High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x83 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. Rev. 1.2 91 C8051F410/1/2/3 SFR Definition 10.4. PSW: Program Status Word R/W R/W R/W R/W R/W R/W R/W R Reset Value CY AC F0 RS1 RS0 OV F1 PARITY 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xD0 Bit0 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 arithmetic operation resulted in a carry into (addition) or a borrow from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations. Bit5: F0: User Flag 0. This is a bit-addressable, general purpose flag for use under software control. Bits4–3: RS1–RS0: Register Bank Select. These bits select which register bank is used during register accesses. RS1 0 0 1 1 Bit2: Bit1: Bit0: 92 RS0 0 1 0 1 Register Bank 0 1 2 3 Address 0x00–0x07 0x08–0x0F 0x10–0x17 0x18–0x1F OV: Overflow Flag. This bit is set to 1 under the following circumstances: • An ADD, ADDC, or SUBB instruction causes a sign-change overflow. • A MUL instruction results in an overflow (result is greater than 255). • A DIV instruction causes a divide-by-zero condition. The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other cases. F1: User Flag 1. This is a bit-addressable, general purpose flag for use under software control. PARITY: Parity Flag. This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum is even. Rev. 1.2 C8051F410/1/2/3 SFR Definition 10.5. ACC: Accumulator R/W R/W R/W R/W R/W R/W R/W R/W Reset Value ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xE0 Bit0 Bits7–0: ACC: Accumulator. This register is the accumulator for arithmetic operations. SFR Definition 10.6. B: B Register R/W R/W R/W R/W R/W R/W R/W R/W Reset Value B.7 B.6 B.5 B.4 B.3 B.2 B.1 B.0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xF0 Bit0 Bits7–0: B: B Register. This register serves as a second accumulator for certain arithmetic operations. 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 interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states; the external oscillator is not affected). Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the least power. SFR Definition 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 when they are not in use. Turning off the oscillators lowers power consumption considerably; 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 153. Rev. 1.2 93 C8051F410/1/2/3 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 data. All analog and digital peripherals can remain active during Idle mode. Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The pending interrupt will be serviced and the next instruction to be executed after the return from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. 10.3.2. Stop Mode Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset sequence and begins program execution at address 0x0000. If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode. The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the MCD timeout period of 100 s. 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 153. SFR Definition 10.7. PCON: Power Control R/W R/W R/W R/W R/W R/W Reserved Reserved Reserved Reserved Reserved Reserved Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 R/W R/W Reset Value STOP IDLE 00000000 Bit1 Bit0 SFR Address: 0x87 Bits7–2: Reserved. Bit1: STOP: 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. Writing 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.) 94 Rev. 1.2 C8051F410/1/2/3 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 are 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 program 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 implement 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 space for non-volatile data storage. Refer to Section “16. Flash Memory” on page 125 for further details. Rev. 1.2 95 C8051F410/1/2/3 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 memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (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 134. 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 bits in the program status word, RS0 (PSW.3) and RS1 (PSW.4), select the active register bank (see description of the PSW in SFR Definition 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 index 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 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or destination). The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where XX is the byte address and B is the bit position within the byte. For example, the instruction: MOV C, 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 designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be initialized to a location in the data memory not being used for data storage. The stack depth can extend up to 256 bytes. 96 Rev. 1.2 C8051F410/1/2/3 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 System Controller. The SFR registers are accessed anytime the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, IE, etc.) are bit-addressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate effect and should be avoided. Refer to the corresponding pages of the data sheet, as indicated in Table 11.2, for a detailed description of each register. Table 11.1. Special Function Register (SFR) Memory Map F8 F0 E8 E0 D8 D0 C8 C0 B8 B0 A8 A0 98 90 88 80 SPI0CN B ADC0CN ACC PCA0CN PSW TMR2CN SMB0CN IP P0ODEN IE P2 SCON0 P1 TCON P0 0(8) PCA0L P0MDIN PCA0CPL1 XBR0 PCA0MD REF0CN REG0CN SMB0CF IDA0CN OSCXCN CLKSEL SPI0CFG SBUF0 TMR3CN TMOD SP 1(9) PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 PCA0CPH4 P1MDIN P2MDIN IDA1L IDA1H EIP1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 XBR1 PFE0CN IT01CF EIE1 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPL5 PCA0CPH5 P0SKIP P1SKIP P2SKIP TMR2RLL TMR2RLH TMR2L TMR2H PCA0CPM5 SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH ADC0TK ADC0MX ADC0CF ADC0L ADC0H OSCICN OSCICL IDA1CN FLSCL EMI0CN CLKMUL RTC0ADR RTC0DAT RTC0KEY SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT CPT1CN CPT0CN CPT1MD CPT0MD CPT1MX TMR3RLL TMR3RLH TMR3L TMR3H IDA0L TL0 TL1 TH0 TH1 CKCON DPL DPH CRC0CN CRC0IN CRC0DAT 2(A) 3(B) 4(C) 5(D) 6(E) VDM0CN EIP2 RSTSRC EIE2 CRC0FLIP P0MAT P1MAT P0MASK P1MASK FLKEY ONESHOT CPT0MX IDA0H PSCTL PCON 7(F) (bit addressable) Rev. 1.2 97 C8051F410/1/2/3 Table 11.2. Special Function Registers SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register ACC ADC0CF ADC0CN ADC0H ADC0L ADC0GTH ADC0GTL ADC0LTH ADC0LTL ADC0MX ADC0TK B CKCON CLKMUL CLKSEL CPT0CN CPT0MD CPT0MX CPT1CN CPT1MD CPT1MX CRC0CN CRC0IN CRC0DAT CRC0FLIP DPH DPL EIE1 EIE2 EIP1 EIP2 EMI0CN FLKEY FLSCL IDA0H IDA0L IDA0CN IDA1H 98 Address 0xE0 0xBC 0xE8 0xBE 0xBD 0xC4 0xC3 0xC6 0xC5 0xBB 0xBA 0xF0 0x8E 0xAB 0xA9 0x9B 0x9D 0x9F 0x9A 0x9C 0x9E 0x84 0x85 0x86 0xDF 0x83 0x82 0xE6 0xE7 0xF6 0xF7 0xAA 0xB7 0xB6 0x97 0x96 0xB9 0xF5 Description Accumulator ADC0 Configuration ADC0 Control ADC0 ADC0 ADC0 Greater-Than Data High Byte ADC0 Greater-Than Data Low Byte ADC0 Less-Than Data High Byte ADC0 Less-Than Data Low Byte ADC0 Channel Select ADC0 Tracking Mode Select B Register Clock Control Clock Multiplier Clock Select Comparator0 Control Comparator0 Mode Selection Comparator0 MUX Selection Comparator1 Control Comparator1 Mode Selection Comparator1 MUX Selection CRC0 Control CRC0 Data Input CRC0 Data Output CRC0 Bit Flip Data Pointer High Data Pointer Low Extended Interrupt Enable 1 Extended Interrupt Enable 2 Extended Interrupt Priority 1 Extended Interrupt Priority 2 External Memory Interface Control Flash Lock and Key Flash Scale Current Mode DAC0 High Byte Current Mode DAC0 Low Byte Current Mode DAC0 Control Current Mode DAC1 High Byte Rev. 1.2 Page 93 54 56 55 55 58 58 59 59 53 57 93 222 160 161 78 80 79 83 82 81 116 116 117 117 91 91 106 108 107 108 134 131 132 65 66 65 67 C8051F410/1/2/3 Table 11.2. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address Description Page IDA1L IDA1CN IE IP IT01CF ONESHOT OSCICL OSCICN OSCXCN 0xF4 0xB5 0xA8 0xB8 0xE4 0xAF 0xB3 0xB2 0xB1 Current Mode DAC1 Low Byte Current Mode DAC1 Control Interrupt Enable Interrupt Priority INT0/INT1 Configuration Flash Oneshot Period Internal Oscillator Calibration Internal Oscillator Control External Oscillator Control 67 66 104 105 110 133 154 154 158 P0 P0MASK P0MAT P0MDIN P0MDOUT P0ODEN P0SKIP P1 P1MASK P1MAT P1MDIN P1MDOUT P1SKIP P2 P2MDIN P2MDOUT P2SKIP PCA0CN PCA0CPH0 PCA0CPH1 PCA0CPH2 PCA0CPH3 PCA0CPH4 PCA0CPH5 PCA0CPL0 PCA0CPL1 PCA0CPL2 PCA0CPL3 PCA0CPL4 0x80 0xC7 0xD7 0xF1 0xA4 0xB0 0xD4 0x90 0xBF 0xCF 0xF2 0xA5 0xD5 0xA0 0xF3 0xA6 0xD6 0xD8 0xFC 0xEA 0xEC 0xEE 0xFE 0xD3 0xFB 0xE9 0xEB 0xED 0xFD Port 0 Latch Port 0 Mask Port 0 Match Port 0 Input Mode Configuration Port 0 Output Mode Configuration Port 0 Overdrive Port 0 Skip Port 1 Latch Port 1 Mask Port 1 Match Port 1 Input Mode Configuration Port 1 Output Mode Configuration Port 1 Skip Port 2 Latch Port 2 Input Mode Configuration Port 2 Output Mode Configuration Port 2 Skip PCA Control PCA Capture 0 High PCA Capture 1 High PCA Capture 2 High PCA Capture 3 High PCA Capture 4 High PCA Capture 5 High PCA Capture 0 Low PCA Capture 1 Low PCA Capture 2 Low PCA Capture 3 Low PCA Capture 4 Low 143 145 145 143 144 145 144 146 148 148 146 147 147 149 149 150 150 246 249 249 249 249 249 249 249 249 249 249 249 Rev. 1.2 99 C8051F410/1/2/3 Table 11.2. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address PCA0CPL5 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPM5 PCA0H PCA0L 0xD2 0xDA 0xDB 0xDC 0xDD 0xDE 0xCE 0xFA 0xF9 PCA Capture 5 Low PCA Module 0 Mode PCA Module 1 Mode PCA Module 2 Mode PCA Module 3 Mode PCA Module 4 Mode PCA Module 5 Mode PCA Counter High PCA Counter Low 249 248 248 248 248 248 248 249 249 PCA0MD PCON PFE0CN PSCTL PSW REF0CN REG0CN RTC0ADR RTC0DAT RTC0KEY RSTSRC SBUF0 SCON0 SMB0CF SMB0CN SMB0DAT SP SPI0CFG SPI0CKR SPI0CN SPI0DAT TCON TH0 TH1 TL0 TL1 TMOD TMR2CN TMR2H 0xD9 0x87 0xE3 0x8F 0xD0 0xD1 0xC9 0xAC 0xAD 0xAE 0xEF 0x99 0x98 0xC1 0xC0 0xC2 0x81 0xA1 0xA2 0xF8 0xA3 0x88 0x8C 0x8D 0x8A 0x8B 0x89 0xC8 0xCD PCA Mode Power Control Prefetch Engine Control Program Store R/W Control Program Status Word Voltage Reference Control Voltage Regulator Control smaRTClock Address smaRTClock Data smaRTClock Lock and Key Reset Source Configuration/Status UART0 Data Buffer UART0 Control SMBus Configuration SMBus Control SMBus Data Stack Pointer SPI Configuration SPI Clock Rate Control SPI Control SPI Data Timer/Counter Control Timer/Counter 0 High Timer/Counter 1 High Timer/Counter 0 Low Timer/Counter 1 Low Timer/Counter Mode Timer/Counter 2 Control Timer/Counter 2 High 247 94 111 131 92 71 74 167 168 166 123 199 198 183 185 187 90 209 211 210 212 220 223 223 223 223 221 227 228 100 Description Rev. 1.2 Page C8051F410/1/2/3 Table 11.2. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address TMR2L TMR2RLH TMR2RLL TMR3CN TMR3H TMR3L TMR3RLH TMR3RLL 0xCC 0xCB 0xCA 0x91 0x95 0x94 0x93 0x92 VDM0CN XBR0 XBR1 Description Page 228 228 228 232 233 233 233 233 0xFF Timer/Counter 2 Low Timer/Counter 2 Reload High Timer/Counter 2 Reload Low Timer/Counter 3Control Timer/Counter 3 High Timer/Counter 3 Low Timer/Counter 3 Reload High Timer/Counter 3 Reload Low VDD Monitor Control 0xE1 0xE2 Port I/O Crossbar Control 0 Port I/O Crossbar Control 1 141 142 Rev. 1.2 121 101 C8051F410/1/2/3 12. Interrupt Handler The C8051F41x family includes an extended interrupt system supporting a total of 18 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external input pins varies according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1. If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI instruction, which returns program execution to the next instruction that would have been executed if the interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.) Each interrupt source can be individually enabled or disabled through the use of an associated interrupt enable bit in 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 recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interruptenable 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 are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI) instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction. 12.1. MCU Interrupt Sources and Vectors The MCUs support 18 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order, and control bits are summarized in Table 12.1 on page 103. Refer to the data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). 12.2. Interrupt Priorities Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is used to arbitrate, given in Table 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 cycles: 1 clock cycle to detect the interrupt, 1 clock cycle to execute a single instruction, and 5 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next 102 Rev. 1.2 C8051F410/1/2/3 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 cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction. Interrupt Priority Pending Flag Vector Order Reset 0x0000 Top External Interrupt 0 (/INT0) Timer 0 Overflow External Interrupt 1 (/INT1) Timer 1 Overflow 0x0003 0x000B 0x0013 0x001B 0 1 2 3 UART0 0x0023 4 Timer 2 Overflow 0x002B 5 SPI0 0x0033 6 SMB0 0x003B 7 smaRTClock 0x0043 8 ADC0 Window Comparator 0x004B 9 ADC0 End of Conversion 0x0053 10 Programmable Counter Array 0x005B 11 Comparator0 0x0063 12 Comparator1 0x006B 13 Timer 3 Overflow 0x0073 14 Voltage Regulator Dropout 0x007B 15 Port Match 16 0x0083 Cleared by HW? Interrupt Source Bit addressable? Table 12.1. Interrupt Summary Enable Flag Priority Control Y Y Y Y Y Y Y Y Always Enabled EX0 (IE.0) ET0 (IE.1) EX1 (IE.2) ET1 (IE.3) Y N ES0 (IE.4) PS0 (IP.4) Y N ET2 (IE.5) PT2 (IP.5) Y N ESPI0 (IE.6) PSPI0 (IP.6) Y N ESMB0 (EIE1.0) PSMB0 (EIP1.0) N N ERTC0 (EIE1.1) PRTC0 (EIP1.1) EWADC0 (EIE1.2) EADC0 AD0INT (ADC0STA.5) Y N (EIE1.3) CF (PCA0CN.7) EPCA0 Y N CCFn (PCA0CN.n) (EIE1.4) CP0FIF (CPT0CN.4) ECP0 N N CP0RIF (CPT0CN.5) (EIE1.5) CP1FIF (CPT1CN.4) ECP1 N N CP1RIF (CPT1CN.5) (EIE1.6) ET3 TF3H (TMR3CN.7) N N (EIE1.7) TF3L (TMR3CN.6) EREG0 N/A N/A N/A (EIE2.0) EMAT N/A N/A N/A (EIE2.1) PWADC0 (EIP1.2) PADC0 (EIP1.3) PPCA0 (EIP1.4) PCP0 (EIP1.5) PCP1 (EIP1.6) PT3 (EIP1.7) PREG0 (EIP2.0) PMAT (EIP2.1) None IE0 (TCON.1) TF0 (TCON.5) IE1 (TCON.3) TF1 (TCON.7) RI0 (SCON0.0) TI0 (SCON0.1) TF2H (TMR2CN.7) TF2L (TMR2CN.6) SPIF (SPI0CN.7) WCOL (SPI0CN.6) MODF (SPI0CN.5) RXOVRN (SPI0CN.4) SI (SMB0CN.0) ALRM (RTC0CN.2) OSCFAIL (RTC0CN.5) AD0WINT (ADC0CN.3) Rev. 1.2 N/A N/A Y N Always Highest PX0 (IP.0) PT0 (IP.1) PX1 (IP.2) PT1 (IP.3) 103 C8051F410/1/2/3 12.4. Interrupt Register Descriptions The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). SFR Definition 12.1. IE: Interrupt Enable 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 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: 104 EA: Global Interrupt Enable. This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings. 0: Disable all interrupt sources. 1: Enable each interrupt according to its individual mask setting. ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of the SPI0 interrupts. 0: Disable all SPI0 interrupts. 1: Enable interrupt requests generated by SPI0. ET2: Enable Timer 2 Interrupt. This bit sets the masking of the Timer 2 interrupt. 0: Disable Timer 2 interrupt. 1: Enable interrupt requests generated by the TF2L or TF2H flags. ES0: Enable UART0 Interrupt. This bit sets the masking of the UART0 interrupt. 0: Disable UART0 interrupt. 1: Enable UART0 interrupt. ET1: Enable Timer 1 Interrupt. This bit sets the masking of the Timer 1 interrupt. 0: Disable all Timer 1 interrupt. 1: Enable interrupt requests generated by the TF1 flag. EX1: Enable External Interrupt 1. This bit sets the masking of External Interrupt 1. 0: Disable external interrupt 1. 1: Enable interrupt requests generated by the /INT1 input. ET0: Enable Timer 0 Interrupt. This bit sets the masking of the Timer 0 interrupt. 0: Disable all Timer 0 interrupt. 1: Enable interrupt requests generated by the TF0 flag. EX0: Enable External Interrupt 0. This bit sets the masking of External Interrupt 0. 0: Disable external interrupt 0. 1: Enable interrupt requests generated by the /INT0 input. Rev. 1.2 C8051F410/1/2/3 SFR Definition 12.2. IP: Interrupt Priority 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 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: UNUSED. Read = 1, Write = don't care. 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. PT2: Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupt set to low priority level. 1: Timer 2 interrupt set to high priority level. PS0: UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupt set to low priority level. 1: UART0 interrupt set to high priority level. PT1: Timer 1 Interrupt Priority Control. This bit sets the priority of the Timer 1 interrupt. 0: Timer 1 interrupt set to low priority level. 1: Timer 1 interrupt set to high priority level. PX1: External Interrupt 1 Priority Control. This bit sets the priority of the External Interrupt 1 interrupt. 0: External Interrupt 1 set to low priority level. 1: External Interrupt 1 set to high priority level. PT0: Timer 0 Interrupt Priority Control. This bit sets the priority of the Timer 0 interrupt. 0: Timer 0 interrupt set to low priority level. 1: Timer 0 interrupt set to high priority level. PX0: External Interrupt 0 Priority Control. This bit sets the priority of the External Interrupt 0 interrupt. 0: External Interrupt 0 set to low priority level. 1: External Interrupt 0 set to high priority level. Rev. 1.2 105 C8051F410/1/2/3 SFR Definition 12.3. EIE1: Extended Interrupt Enable 1 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 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: 106 ET3: Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable Timer 3 interrupts. 1: Enable interrupt requests generated by the TF3L or TF3H flags. ECP1: Enable Comparator1 (CP1) Interrupt. This bit sets the masking of the CP1 interrupt. 0: Disable CP1 interrupts. 1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags. ECP0: Enable Comparator0 (CP0) Interrupt. This bit sets the masking of the CP0 interrupt. 0: Disable CP0 interrupts. 1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags. EPCA0: Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable all PCA0 interrupts. 1: Enable interrupt requests generated by PCA0. EADC0: Enable ADC0 Conversion Complete Interrupt. This bit sets the masking of the ADC0 Conversion Complete interrupt. 0: Disable ADC0 Conversion Complete interrupt. 1: Enable interrupt requests generated by the AD0INT flag. EWADC0: Enable 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. 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. ESMB0: Enable SMBus (SMB0) Interrupt. This bit sets the masking of the SMB0 interrupt. 0: Disable all SMB0 interrupts. 1: Enable interrupt requests generated by SMB0. Rev. 1.2 C8051F410/1/2/3 SFR Definition 12.4. EIP1: Extended Interrupt Priority 1 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 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: 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. 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. 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. PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control. This bit sets the priority of the PCA0 interrupt. 0: PCA0 interrupt set to low priority level. 1: PCA0 interrupt set to high priority level. PADC0: ADC0 Conversion Complete Interrupt Priority Control. This bit sets the priority of the ADC0 Conversion Complete interrupt. 0: ADC0 Conversion Complete interrupt set to low priority level. 1: ADC0 Conversion Complete interrupt set to high priority level. PWADC0: ADC0 Window Comparison 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. PRTC0: smaRTClock Interrupt Priority Control. 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. PSMB0: SMBus (SMB0) Interrupt Priority Control. This bit sets the priority of the SMB0 interrupt. 0: SMB0 interrupt set to low priority level. 1: SMB0 interrupt set to high priority level. Rev. 1.2 107 C8051F410/1/2/3 SFR Definition 12.5. EIE2: Extended Interrupt Enable 2 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 - - - - - - EMAT EREG0 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xE7 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 interrupt. 0: Disable the Voltage Regulator Dropout interrupt. 1: Enable the Voltage Regulator Dropout interrupt. SFR Definition 12.6. EIP2: Extended Interrupt Priority 2 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - - - - - - PMAT PREG0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xF7 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. 108 Rev. 1.2 C8051F410/1/2/3 12.5. External Interrupts The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or active low; the IT0 and IT1 bits in TCON (Section “24.1. Timer 0 and Timer 1” on page 216) select level or edge sensitive. The table below lists the possible configurations. IT0 1 1 0 0 IN0PL 0 1 0 1 /INT0 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive IT1 1 1 0 0 IN1PL 0 1 0 1 /INT1 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive /INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 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 137 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 corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It must then deactivate the interrupt request before execution of the ISR completes or another interrupt request will be generated. Rev. 1.2 109 C8051F410/1/2/3 SFR Definition 12.7. IT01CF: INT0/INT1 Configuration 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 220 for INT0/1 edge- or level-sensitive interrupt selection. 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 independent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to ‘1’ the corresponding bit in register P0SKIP). IN1SL2–0 000 001 010 011 100 101 110 111 /INT1 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 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 independent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to ‘1’ the corresponding bit in register P0SKIP). IN0SL2–0 000 001 010 011 100 101 110 111 110 /INT0 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 Rev. 1.2 C8051F410/1/2/3 13. Prefetch Engine The C8051F41x family of devices incorporate a 2-byte prefetch engine. Due to Flash access time specifications, the prefetch engine is necessary for full-speed (50 MHz) code execution. Instructions are read from Flash memory two bytes at a time by the prefetch 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 each read. When operating with a system clock of greater than 25 MHz (up to 50 MHz), the prefetch engine must be enabled by setting the PFEN bit to ‘1’, and 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 R R R/W R R R R PFEN Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 R/W Reset Value FLBWE 00100000 Bit0 SFR Address: 0xE3 Bits 7–6: Unused. Read = 00b; Write = Don’t Care Bit 5: PFEN: Prefetch Enable. This bit enables the prefetch engine. 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 125. Rev. 1.2 111 C8051F410/1/2/3 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 manipulation. 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-bit CRC algorithm performed by the hardware: 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, the current CRC result will be the set initial 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). 112 Rev. 1.2 C8051F410/1/2/3 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 > 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 algorithm (an initial value of 0xFFFFFFFF is used): 114 Rev. 1.2 C8051F410/1/2/3 Table 14.2. Example 32-bit CRC Outputs Input Output 0x63 0xF9462090 0xAA, 0xBB, 0xCC 0x41B207B3 0x00, 0x00, 0xAA, 0xBB, 0xCC 0x78D129BC 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 0x00000000 or ‘1’ for 0xFFFFFFFF). 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 targeted by read and write operations on CRC0DAT and increment after each 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 Rev. 1.2 115 C8051F410/1/2/3 SFR Definition 14.1. CRC0CN: CRC0 Control R R R - - - Bit7 Bit6 Bit5 R/W W R/W CRC0SEL CRC0INIT CRC0VAL Bit4 Bit3 Bit2 R/W R/W CRC0PNT Bit1 Reset Value 00000000 Bit0 SFR Address: 0x84 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 upon each read or write. For CRC0SEL = 0: 00: CRC0DAT accesses bits 7–0 of the 32-bit CRC result. 01: CRC0DAT accesses bits 15–8 of the 32-bit CRC result. 10: CRC0DAT accesses bits 23–16 of the 32-bit CRC result. 11: CRC0DAT accesses bits 31–24 of the 32-bit CRC result. For CRC0SEL = 1: 00: CRC0DAT accesses bits 7–0 of the 16-bit CRC result. 01: CRC0DAT accesses bits 15–8 of the 16-bit CRC result. 10: CRC0DAT accesses bits 7–0 of the 16-bit CRC result. 11: CRC0DAT accesses bits 15–8 of the 16-bit CRC result. SFR Definition 14.2. CRC0IN: CRC0 Data Input 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 Bits 7–0: CRC0IN: CRC Data Input Each write to CRCIN results in the written data being computed into the existing CRC result. 116 Rev. 1.2 C8051F410/1/2/3 SFR Definition 14.3. CRC0DAT: CRC0 Data Output R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0x86 Bits 7–0: CRC0DAT: Indirect CRC Result Data Bits. Each operation performed on CRC0DAT targets the CRC result bits pointed to by CRC0PNT. SFR Definition 14.4. CRC0FLIP: CRC0 Bit Flip R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xDF 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 back will be 0xA0. Rev. 1.2 117 C8051F410/1/2/3 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 data on the stack is not altered. The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled during and after the reset. For VDD Monitor and power-on resets, the RSTb pin is driven low until the device exits the reset state. Note: When VIO rises faster than VDD, which can happen when VREGIN and VIO are tied together, a delay created between GPIO power (VIO) and the logic controlling GPIO (VDD) results in a temporary unknown state at the GPIO pins. When VIO rises faster than VDD, the GPIO may enter the following states: floating, glitch low, or glitch high. Cross coupling VIO and VDD with a 4.7 μF capacitor mitigates the root cause of the problem by allowing VIO and VDD to rise at the same rate. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section “19. Oscillators” on page 152 for information on selecting and configuring the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock source (Section “25.3. Watchdog Timer Mode” on page 242 details the use of the Watchdog Timer). Program execution begins at location 0x0000. Figure 15.1. Reset Sources 118 Rev. 1.2 C8051F410/1/2/3 15.1. Power-On Reset During power-up, the device is held in a reset state and the RSTb 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 VREGIN ramp time increases (VREGIN ramp time is defined as how fast VREGIN ramps from 0 V to ~1.9 V). Figure 15.2 and Figure 15.3 plot 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 VREGIN ramp time is 1 ms; slower ramp times may cause the device to be released from reset before VDD reaches the VRST level. On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other resets). Since all resets cause program execution to begin at the same location (0x0000), software can read the PORSF flag to determine if a power-up was the cause of reset. The contents of internal data memory should be assumed to be undefined after a power-on reset. The VDD monitor is enabled following a power-on reset. Figure 15.2. Power-On Reset Timing Rev. 1.2 119 C8051F410/1/2/3 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 RSTb 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 internal data memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be valid. The VDD monitor is enabled and is selected as a reset source after power-on resets; however its defined state (enabled/disabled) is not altered by any other reset source. For example, if the VDD monitor is 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 software 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 reenabling 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’). Figure 15.3. VDD Monitor Reset Timing 120 Rev. 1.2 C8051F410/1/2/3 See Figure 15.3 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 VDD 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 keep the VDD Monitor enabled as a reset source. SFR Definition 15.1. VDM0CN: VDD Monitor Control 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 Bit7: VDMEN: VDD Monitor Enable. This bit turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system resets until it is also selected as a reset source in register RSTSRC (SFR Definition 15.2). The VDD 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. 15.3. External Reset The external RSTb pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the RSTb pin generates a reset; an external pullup and/or decoupling of the RSTb pin may be necessary to avoid erroneous noise-induced resets. See Table 15.1 for complete RSTb 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 system clock. If the system clock remains high or low for more than 100 μs, the one-shot will time out and generate a reset. After a MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise, this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables it. The state of the RSTb pin is unaffected by this reset. Rev. 1.2 121 C8051F410/1/2/3 15.5. Comparator0 Reset Comparator0 can be configured as a reset source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset source; otherwise, this bit reads ‘0’. The state of the RSTb 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 242; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to ‘1’. The state of the RSTb pin is unaffected by this 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 above 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 attempted above user code space. This occurs when user code attempts 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 127). A Flash write or erase is attempted while the VDD Monitor is disabled. The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RSTb pin is unaffected by this reset. 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 smaRTClock Alarm is enabled and the 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 the RSTb 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’ following a software forced reset. The state of the RSTb pin is unaffected by this reset. 122 Rev. 1.2 C8051F410/1/2/3 SFR Definition 15.2. RSTSRC: Reset Source R/W R R/W RTC0RE FERROR C0RSEF Bit7 Bit6 Bit5 R/W SWRSF Bit4 R R/W WDTRSF MCDRSF Bit3 Bit2 R/W R Reset Value PORSF PINRSF Variable Bit1 Bit0 SFR Address: 0xEF Note: For bits that act as both reset source enables (on a write) and reset indicator flags (on a read), read-modify-write instructions read and modify the source enable only. [This applies to bits: RTC0RE, C0RSEF, SWRSF, MCDRSF, PORSF]. Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 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: smaRTClock is not a reset source. 1: Read: Source of last reset was a smaRTClock alarm or oscillator fail event. Write: smaRTClock is a reset source. 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. C0RSEF: Comparator0 Reset Enable and Flag. 0: Read: Source of last reset was not Comparator0. Write: Comparator0 is not a reset source. 1: Read: Source of last reset was Comparator0. Write: Comparator0 is a reset source (active-low). 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. WDTRSF: Watchdog Timer Reset Flag. 0: Source of last reset was not a WDT timeout. 1: Source of last reset was a WDT timeout. MCDRSF: Missing Clock Detector Flag. 0: Read: Source of last reset was not a Missing Clock Detector timeout. 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. 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 reset source. Note: writing ‘1’ to this bit before the VDD monitor 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. PINRSF: HW Pin Reset Flag. 0: Source of last reset was not RSTb pin. 1: Source of last reset was RSTb pin. Rev. 1.2 123 C8051F410/1/2/3 Table 15.1. Reset Electrical Characteristics –40 to +85 °C unless otherwise specified. Typical values are given at 25 ºC. Parameter Min Typ Max — — — — 50 800 — — — — 40 400 RSTb Input High Voltage 0.7 x VIO — — V RSTb Input Low Voltage — — 0.3 x VIO V VIO = 2.0 V — 150 — VIO = 5.0 V — 70 — VDD Monitor Threshold (VRST-LOW) 1.9 1.95 2.0 V VDD Monitor Threshold (VRST-HIGH) 2.25 2.3 2.35 V 50 350 650 μs — — 180 μs 20 — — μs — 0.7 70 μA — — 1 ms RSTb Output Low Voltage RSTb Input Pullup Impedance Missing Clock Detector Timeout Reset Time Delay Conditions VIO = 2.0 V: IOL = 70 μA IOL = 8.5 mA VIO = 4.0 V: IOL = 70 μA IOL = 8.5 mA Time from last system clock rising edge to reset initiation Delay between release of any reset source and code execution at location 0x0000 Minimum RSTb Low Time to Generate a System Reset VDD Monitor Supply Current VREGIN Ramp Time 124 VREGIN = 0 V to VREGIN = 1.9 V Rev. 1.2 Units mV k C8051F410/1/2/3 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 Flash bit must be erased to set it back to logic 1. Flash bytes would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operations is not required. Code execution is stalled during Flash write/erase operations. Refer to Table 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 250. For detailed guidelines on writing or erasing Flash from firmware, please see Section “16.4. Flash Write and Erase Guidelines” on page 129. 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 disabled until the next system reset. Flash writes and erases will also be disabled if a Flash write or erase is attempted before the key codes have been written properly. The Flash lock resets after each write or erase; the key codes must be written again before a following Flash operation can be performed. 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 software. A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written. The 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. Step 2. Step 3. Step 4. Step 5. Step 6. Disable interrupts (recommended). Write the first key code to FLKEY: 0xA5. Write the second key code to FLKEY: 0xF1. Set the PSEE bit (register PSCTL). Set the PSWE bit (register PSCTL). 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. Rev. 1.2 125 C8051F410/1/2/3 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. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. Step 8. Disable interrupts. Clear the FLBWE bit (register PFE0CN) to select single-byte write mode. Write '0000' to FLSCL.3–0. Write the first key code to FLKEY: 0xA5. Write the second key code to FLKEY: 0xF1. Set the PSWE bit (register PSCTL). Clear the PSEE bit (register PSCTL). Using the MOVX instruction, write a single data byte to the desired location within the 512byte 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 written 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 following the MOVX write that targets the address ending in 1b. If a byte in the block does not need to be updated in Flash, it should be written to 0xFF. The recommended procedure for writing Flash in blocks is: Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. Step 8. Disable interrupts. Set the FLBWE bit (register PFE0CN) to select block write mode. Write '0000' to FLSCL.3–0. Write the first key code to FLKEY: 0xA5. Write the second key code to FLKEY: 0xF1. Set the PSWE bit (register PSCTL). Clear the PSEE bit (register PSCTL). Using the MOVX instruction, write the first data byte to the even block location (ending in 0b). Step 9. Clear the PSWE bit (register PSCTL). 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). Step 14. Using the MOVX instruction, write the second data byte to the odd block location (ending 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. 126 Rev. 1.2 C8051F410/1/2/3 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 read using the MOVC instruction. Note: MOVX read instructions always target XRAM. 16.3. Security Options The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software 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 altered across the C2 interface. A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program memory from access (reads, writes, or erases) 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. Security Lock Byte: 1’s Complement: Flash pages locked: Addresses locked: 11111101b 00000010b 3 (First two Flash pages + Lock Byte Page) 0x0000 to 0x03FF (first two Flash pages) and 0x7C00 to 0x7DFF (Lock Byte Page) Figure 16.1. Flash Program Memory Map Rev. 1.2 127 C8051F410/1/2/3 The level of Flash security depends on the Flash access method. The three Flash access methods that can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on unlocked pages, and user firmware executing on locked pages. Table 16.1 summarizes the Flash security features of the 'F41x devices. Table 16.1. Flash Security Summary Action C2 Debug Interface Read, Write or Erase unlocked pages (except page with Lock Byte) User Firmware executing from: an unlocked page a locked page Permitted Permitted Permitted 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 Permitted FEDR FEDR 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 Read, Write or Erase locked pages (except page with Lock Byte) Erase page containing Lock Byte (if no pages are locked) Erase page containing Lock Byte - Unlock all pages (if any page is locked) C2DE - C2 Device Erase (Erases all Flash pages including the page containing the Lock Byte) FEDR - Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after reset) - All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset). - Locking any Flash page also locks the page containing the Lock Byte. - Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase. - If user code writes to the Lock Byte, the Lock does not take effect until the next device reset. 128 Rev. 1.2 C8051F410/1/2/3 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 modifying code can result in alteration of Flash memory contents causing a system failure that is only recoverable 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 power supply to ensure that the supply voltages listed in the Absolute Maximum Ratings table are not exceeded. 2. Make certain that the minimum VDD rise time specification of 1 ms is met. If the system cannot meet this rise time specification, then add an external VDD brownout circuit to the /RST pin of the device that holds the device in reset until VDD reaches VRST and re-asserts /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 added precaution, explicitly enable the VDD Monitor and enable the VDD Monitor as a reset source inside the functions that write and erase Flash memory. The VDD Monitor enable instructions should be placed just after the instruction to set PSWE to a '1', but before the Flash write or erase operation instruction. 5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment operators and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC = 0x02" is correct, but "RSTSRC |= 0x02" is incorrect. 6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a '1'. Areas to check are initialization code which enables other reset sources, such as the Missing Clock Detector or Comparator, for example, and instructions which force a Software Reset. A global search on "RSTSRC" can quickly verify this. Rev. 1.2 129 C8051F410/1/2/3 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 sets PSWE to a '1' to write Flash bytes and one routine in code that sets both PSWE and PSEE both to a '1' to erase Flash pages. 8. Minimize the number of variable accesses while PSWE is set to a '1'. Handle pointer address updates and loop maintenance outside the "PSWE = 1; ... PSWE = 0;" area. Code examples showing this can be found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site. 9. Disable interrupts prior to setting PSWE to a '1' and leave them disabled until after PSWE has been reset to '0'. Any interrupts posted during the Flash write or erase operation will be serviced in priority order after the Flash operation has been completed and interrupts have been re-enabled by software. 10. Make certain that the Flash write and erase pointer variables are not located in XRAM. See your compiler documentation for instructions regarding how to explicitly locate variables in different memory areas. 11. Add address bounds checking to the routines that write or erase Flash memory to ensure that a routine called with an illegal address does not result in modification of the Flash. 16.4.3. System Clock 12. If operating from an external crystal, be advised that crystal performance is susceptible to electrical interference and is sensitive to layout and to changes in temperature. If the system is operating in an electrically noisy environment, use the internal oscillator or use an external CMOS clock. 13. If operating from the external oscillator, switch to the internal oscillator during Flash write or erase operations. The external oscillator can continue to run, and the CPU can switch back to the external oscillator after the Flash operation has completed. 130 Rev. 1.2 C8051F410/1/2/3 SFR Definition 16.1. PSCTL: Program Store R/W Control R R R R R R R/W R/W Reset Value - - - - - - PSEE PSWE 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x8F Bits7–2: UNUSED: Read = 000000b, Write = don’t care. Bit1: PSEE: Program Store Erase Enable Setting this bit (in combination with PSWE) allows an entire page of Flash program memory to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter. 0: Flash program memory erasure disabled. 1: Flash program memory erasure enabled. 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 program memory disabled. 1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash memory. SFR Definition 16.2. FLKEY: Flash Lock and Key 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 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 are automatically disabled after the next write or erase is complete. If any writes to FLKEY are performed incorrectly, or if a Flash write or erase operation is attempted while these operations are disabled, the Flash will be permanently locked from writes or erasures until the next device reset. If an application never writes to Flash, it can intentionally lock the Flash by writing a non-0xA5 value to FLKEY from software. Read: When read, bits 1-0 indicate the current Flash lock state. 00: Flash is write/erase locked. 01: The first key code has been written (0xA5). 10: Flash is unlocked (writes/erases allowed). 11: Flash writes/erases disabled until the next reset. Rev. 1.2 131 C8051F410/1/2/3 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 provides 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 read 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 read 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. Step 2. Step 3. Step 4. Step 5. Step 6. Select SYSCLK to 25 MHz or less. Disable the prefetch engine (PFEN = ‘0’ in PFE0CN register). Clear FLRT to ‘0’ (FLSCL register). Set the ONESHOT period bits. Set FLRT to ‘1’ if SYSCLK > 25 MHz. Enable the prefetch engine (PFEN = ‘1’ in PFE0CN register). SFR Definition 16.3. FLSCL: Flash Scale R/W R/W R/W Reserved Reserved Reserved Bit7 Bit6 Bit5 R/W FLRT Bit4 R/W R/W R/W R/W Reset Value Reserved Reserved Reserved Reserved 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xB6 Bits7–5: RESERVED. Read = 000b. Must Write 000b. Bit 4: FLRT: Flash Read Time Control. This bit should be programmed to the smallest 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. 132 Rev. 1.2 C8051F410/1/2/3 SFR Definition 16.4. ONESHOT: Flash Oneshot Period R R R R - - - - Bit7 Bit6 Bit5 Bit4 R/W R/W R/W R/W PERIOD Bit3 Bit2 Reset Value 00001111 Bit1 Bit0 SFR Address: 0xAF Bits7–4: UNUSED. Read = 0000b. Write = don’t care. Bits3–0: PERIOD: Oneshot Period Control 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 bits have no effect when the system clocks is greater than 12.5 MHz and FLRT = 0. FLAS H RDMAX = 5ns +  PERIOD  5ns  Table 16.2. Flash Electrical Characteristics VDD = 2.0 to 2.75 V; –40 to +85 ºC unless otherwise specified. Typical values are given at 25 ºC. Parameter Flash Size Endurance Erase Cycle Time Write Cycle Time Read Cycle Time VDD Conditions C8051F410/1 Min 32768* C8051F412/3 VDD is 2.2 V or greater 16384 FLSCL.3–0 written to '0000' FLSCL.3–0 written to '0000' Write/Erase Operations Typ Max Units — — bytes 20 k 90 k — Erase/Write 16 38 30 20 46 — 24 57 — ms μs ns 2.25 — — V *Note: 512 bytes at addresses 0x7E00 to 0x7FFF are reserved. Rev. 1.2 133 C8051F410/1/2/3 17. External RAM The C8051F41x devices include 2048 bytes of RAM mapped into the external data memory space. All of these address locations may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in SFR Definition 17.1). Note: the MOVX instruction is also used for writes to the Flash memory. See Section “16. Flash Memory” on page 125 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, etc. This is a useful feature when performing a linear memory fill, as the address pointer doesn't have to be reset when reaching the RAM block boundary. SFR Definition 17.1. EMI0CN: External Memory Interface Control R/W R/W R/W R/W R/W - - - - - Bit7 Bit6 Bit5 Bit4 Bit3 R/W R/W R/W PGSEL Bit2 Bit1 Reset Value 00000000 Bit0 SFR Address: 0xAA 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. 134 Rev. 1.2 C8051F410/1/2/3 18. Port Input/Output Digital and analog resources are available through up to 24 I/O pins. Port pins are organized as three bytewide 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 peripheral priority order of the Priority Decoder (Figure 18.3 and Figure 18.4). The registers XBR0 and XBR1, defined 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 151. Figure 18.1. Port I/O Functional Block Diagram Rev. 1.2 135 C8051F410/1/2/3 Figure 18.2. Port I/O Cell Block Diagram Note: When VIO rises faster than VDD, which can happen when VREGIN and VIO are tied together, a delay created between GPIO power (VIO) and the logic controlling GPIO (VDD) results in a temporary unknown state at the GPIO pins. When VIO rises faster than VDD, the GPIO may enter the following states: floating, glitch low, or glitch high. Cross coupling VIO and VDD with a 4.7 μF capacitor mitigates the root cause of the problem by allowing VIO and VDD to rise at the same rate. 136 Rev. 1.2 C8051F410/1/2/3 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 assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that are to be used for analog input, dedicated functions, or GPIO. Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the Crossbar, its corresponding PnSKIP bit should be set. This applies to 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 the Crossbar Decoder priority with 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 Rev. 1.2 137 C8051F410/1/2/3 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 UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously 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. According to the SPI mode, the NSS signal may or may not be routed to a Port pin. 138 Rev. 1.2 C8051F410/1/2/3 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 (PnMDOUT). 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 digital inputs may still be used by analog peripherals; however, this practice is not recommended. Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates a digital input, and a ‘0’ indicates an analog input. All 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 pins when overdriven above VIO (when VIO is 3.3 V nominal). There are two overdrive 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 voltage reaches approximately VIO + 0.7 V. When the corresponding bit in P0ODEN is logic 1, High-Impedance 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 configured 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. Rev. 1.2 139 C8051F410/1/2/3 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 (PnMDOUT). 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 configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is turned off on an output that is driving a ‘0’ and for pins configured for analog input mode to avoid unnecessary power dissipation. Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode Table. 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. 140 Rev. 1.2 C8051F410/1/2/3 SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 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 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: CP1AE: Comparator1 Asynchronous Output Enable 0: Asynchronous CP1 unavailable at Port pin. 1: Asynchronous CP1 routed to Port pin. CP1E: Comparator1 Output Enable 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin. CP0AE: Comparator0 Asynchronous Output Enable 0: Asynchronous CP0 unavailable at Port pin. 1: Asynchronous CP0 routed to Port pin. CP0E: Comparator0 Output Enable 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. SYSCKE: /SYSCLK Output Enable 0: /SYSCLK unavailable at Port pin. 1: /SYSCLK output routed to Port pin. SMB0E: SMBus I/O Enable 0: SMBus I/O unavailable at Port pins. 1: SMBus I/O routed to Port pins. SPI0E: SPI I/O Enable 0: SPI I/O unavailable at Port pins. 1: SPI I/O routed to Port pins. Note that the SPI can be assigned either 3 or 4 GPIO pins. 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. Rev. 1.2 141 C8051F410/1/2/3 SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 R/W R/W WEAKPUD XBARE Bit7 Bit6 R/W R/W R/W T1E T0E ECIE Bit5 Bit4 Bit3 R/W R/W R/W PCA0ME Bit2 Bit1 Reset Value 00000000 Bit0 SFR Address: 0xE2 Bit7: WEAKPUD: Port I/O Weak Pullup Disable. 0: Weak Pullups 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. 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 maintain the output data value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write instructions 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 levels 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 142 Rev. 1.2 C8051F410/1/2/3 (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 interrupt if EMAT (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 153 for more information. SFR Definition 18.3. P0: Port0 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: 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. SFR Definition 18.4. P0MDIN: Port0 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0xF1 Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively). 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 analog input. In order for the P0.n pin to be in analog input mode, there MUST be a '1' in the Port Latch register corresponding to that pin. 1: Corresponding P0.n pin is not configured as an analog input. Rev. 1.2 143 C8051F410/1/2/3 SFR Definition 18.5. P0MDOUT: Port0 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xA4 Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0. 0: Corresponding P0.n Output is open-drain. 1: Corresponding P0.n Output is push-pull. (Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless of the value of P0MDOUT). SFR Definition 18.6. P0SKIP: Port0 Skip 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 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 analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator 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. 144 Rev. 1.2 C8051F410/1/2/3 SFR Definition 18.7. P0MAT: Port0 Match R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0xD7 Bits7–0: P0MAT[7:0]: Port0 Match Value. These bits control the value that unmasked P0 Port pins are compared against. A Port Match event is generated if (P0 & P0MASK) does not equal (P0MAT & P0MASK). SFR Definition 18.8. P0MASK: Port0 Mask R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xC7 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. SFR Definition 18.9. P0ODEN: Port0 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 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, although selecting this mode results in a slight increase in supply current. Port pins configured to Normal Overdrive Mode require approximately 150 μA of input overdrive current when the voltage at the 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. Rev. 1.2 145 C8051F410/1/2/3 SFR Definition 18.10. P1: Port1 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: 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. SFR Definition 18.11. P1MDIN: Port1 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0xF2 Bits7–0: Analog Input Configuration Bits for P1.7–P1.0 (respectively). 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 analog input. In order for the P1.n pin to be in analog input mode, there MUST be a '1' in the Port Latch register corresponding to that pin. 1: Corresponding P1.n pin is not configured as an analog input. 146 Rev. 1.2 C8051F410/1/2/3 SFR Definition 18.12. P1MDOUT: Port1 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xA5 Bits7–0: Output Configuration Bits for P1.7–P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0. 0: Corresponding P1.n Output is open-drain. 1: Corresponding P1.n Output is push-pull. SFR Definition 18.13. P1SKIP: Port1 Skip 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 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 analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator 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. Rev. 1.2 147 C8051F410/1/2/3 SFR Definition 18.14. P1MAT: Port1 Match R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 SFR Address: 0xCF Bits7–0: P1MAT[7:0]: Port1 Match Value. These bits control the value that unmasked P0 Port pins are compared against. A Port Match event is generated if (P1 & P1MASK) does not equal (P1MAT & P1MASK). SFR Definition 18.15. P1MASK: Port1 Mask R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBF Bits7–0: 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. 148 Rev. 1.2 C8051F410/1/2/3 SFR Definition 18.16. P2: Port2 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: 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. SFR Definition 18.17. P2MDIN: Port2 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xF3 Bits7–0: Analog Input Configuration Bits for P2.7–P2.0 (respectively). 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 analog input. In order for the P2.n pin to be in analog input mode, there MUST be a '1' in the Port Latch register corresponding to that pin. 1: Corresponding P2.n pin is not configured as an analog input. Rev. 1.2 149 C8051F410/1/2/3 SFR Definition 18.18. P2MDOUT: Port2 Output Mode R R R R R R R R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA6 Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in register P2MDIN is logic 0. 0: Corresponding P2.n Output is open-drain. 1: Corresponding P2.n Output is push-pull. SFR Definition 18.19. P2SKIP: Port2 Skip 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 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 analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator 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. 150 Rev. 1.2 C8051F410/1/2/3 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 IOH = –3 mA, Port I/O push-pull Min VIO – 0.5 Typ Max — — IOH = –70 μA, Port I/O push-pull VIO – 50 mV — — — — — — 50 800 — — — — 40 400 Input High Voltage VIO x 0.7 — — V Input Low Voltage — — VIO x 0.3 V — < 0.1 ±1 μA — 120 — k Output High Voltage Output Low Voltage Input Leakage Current VIO = 2.0 V: IOL = 70 μA IOL = 8.5 mA VIO = 4.0 V: IOL = 70 μA IOL = 8.5 mA Weak Pullup Off Weak Pullup Impedance Rev. 1.2 Units V mV 151 C8051F410/1/2/3 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 possible 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), or 2/7: Internal Oscillator x 2, External Oscillator x 2, or External Oscillator x 4. Oscillator electrical specifications are given in Table 19.1 on page 162. Figure 19.1. Oscillator Diagram 19.1. Programmable Internal Oscillator All C8051F41x devices include a programmable 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 obtain a 24.5 MHz frequency. Electrical specifications for the precision internal oscillator are given in Table 19.1 on page 162. 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. 152 Rev. 1.2 C8051F410/1/2/3 19.1.1. Internal Oscillator Suspend Mode When software writes a logic 1 to SUSPEND (OSCICN.5), the internal oscillator is suspended. If the system 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 Match Event. Port 1 Match Event. Comparator 0 enabled and output is logic 0. Comparator 1 enabled and output is logic 0. smaRTClock Oscillator Fail Event. smaRTClock 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. Note: The wake sources for Suspend mode do not require the associated interrupt to be enabled to wake the device from Suspend. Rev. 1.2 153 C8051F410/1/2/3 SFR Definition 19.1. OSCICN: Internal Oscillator Control R/W R R/W IOSCEN IFRDY SUSPEND Bit7 Bit6 Bit5 R R R/W R/W R/W Reset Value - - IFCN2 IFCN1 IFCN0 11000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xB2 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 oscillator 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 Control 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. SFR Definition 19.2. OSCICL: Internal Oscillator Calibration R R/W R/W R/W Bit6 Bit5 Bit4 Bit7 R/W R/W R/W R/W Bit2 Bit1 Bit0 OSCICL Bit3 Reset Value Varies SFR Address: 0xB3 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 reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz. 154 Rev. 1.2 C8051F410/1/2/3 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 crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 19.1. A 10 Mresistor also must be wired across the XTAL1 and XTAL2 pins for the crystal/resonator configuration. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown in Option 2, 3, or 4 of Figure 19.1. The type of external oscillator must be selected in the OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 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 configured to skip the Port pins used by the oscillator circuit; see Section “18.1. Priority Crossbar Decoder” on page 137 for Crossbar configuration. Additionally, when using the external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs (with ‘1's in the corresponding Port Latch). In CMOS clock mode, the associated pin should be configured as a digital input. See Section “18.2. Port I/O Initialization” on page 139 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 226 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 216) and the Programmable Counter Array (PCA) (Section “25. Programmable Counter Array (PCA0)” on page 234). 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 frequency. 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 MCU, the circuit should 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 table in SFR Definition 19.3. For example, a 12 MHz crystal requires an XFCN setting of 111b. Rev. 1.2 155 C8051F410/1/2/3 When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. Force the XTAL1 and XTAL2 pins low by writing 0's to the port latch. Configure XTAL1 and XTAL2 as analog inputs. Release the crystal pins by writing ‘1's to the port latch. Enable the external oscillator. Wait at least 1 ms. Poll for XTLVLD => '1'. Switch the system clock to the external oscillator. Note: Tuning-fork crystals may require additional settling time before XTLVLD returns 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 crystal 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 total value of the capacitors and the stray capacitance 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. 156 Rev. 1.2 C8051F410/1/2/3 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 determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first select the RC network value to produce the desired frequency of oscillation. If the frequency desired is 100 kHz, let R = 246 k 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 frequency 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 Factor 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. Rev. 1.2 157 C8051F410/1/2/3 SFR Definition 19.3. OSCXCN: External Oscillator Control R R/W R/W R/W R/W XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 Reserved Bit7 Bit6 Bit5 Bit4 Bit3 R/W R/W R/W Reset Value XFCN2 XFCN1 XFCN0 00000000 Bit2 Bit1 Bit0 SFR Address: 0xB1 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 Clock Mode. 011: External CMOS Clock Mode with divide by 2 stage. 100: RC Oscillator Mode. 101: Capacitor Oscillator Mode. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. Bit3: RESERVED. Read = 0b; Must write 0b. Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits. 000-111: See table below: XFCN 000 001 010 011 100 101 110 111 Crystal (XOSCMD = 11x) f  20 kHz 20 kHz f 58 kHz 58 kHz  f 155 kHz 155 kHz  f 415 kHz 415 kHz  f 1.1 MHz 1.1 MHz  f 3.1 MHz 3.1 MHz  f 8.2 MHz 8.2 MHz  f 25 MHz RC (XOSCMD = 10x) f 25 kHz 25 kHz f 50 kHz 50 kHz f 100 kHz 100 kHz f 200 kHz 200 kHz f 400 kHz 400 kHz f 800 kHz 800 kHz f 1.6 MHz 1.6 MHz f 3.2 MHz 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 k 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 158 Rev. 1.2 C (XOSCMD = 10x) K Factor = 0.87 K Factor = 2.6 K Factor = 7.7 K Factor = 22 K Factor = 65 K Factor = 180 K Factor = 664 K Factor = 1590 C8051F410/1/2/3 19.3. Clock Multiplier The Clock Multiplier generates an output clock which is 4 times the input clock frequency scaled by a programmable 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 external oscillators divided 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 Section 19.4 for details on system clock selection. The Clock Multiplier is configured via the CLKMUL register (SFR Definition 19.4). The procedure for configuring and enabling the Clock Multiplier is as follows: 1. 2. 3. 4. 5. 6. 7. Reset the Multiplier by writing 0x00 to register CLKMUL. Select the Multiplier input source via the MULSEL bits. Select the Multiplier output scaling factor via the MULDIV bits Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80). Delay for >5 μs. Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0). 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 source. The Clock Multiplier allows faster operation of the CIP-51 core and is intended to generate an output frequency 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 generated 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 Rev. 1.2 159 C8051F410/1/2/3 SFR Definition 19.4. CLKMUL: Clock Multiplier Control R/W MULEN Bit7 R/W R R/W MULINIT MULRDY Bit6 Bit5 R/W R/W R/W Bit2 Bit1 MULDIV Bit4 Bit3 R/W MULSEL Reset Value 00000000 Bit0 SFR Address: 0xAB Note: The maximum SYSCLK is 50 MHz, so the Clock Multiplier output should be scaled accordingly. 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. Once 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 Output scaled by a factor of 2/3*. 100: Clock Multiplier Output scaled by a factor of 2/4 (or 1/2). 101: Clock Multiplier Output scaled by a factor of 2/5*. 110: Clock Multiplier Output scaled by a factor of 2/6 (or 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. 160 MULSEL Selected Input Clock 00 01 10 11 Internal Oscillator / 2 External Oscillator External Oscillator / 2 Internal Oscillator Rev. 1.2 Clock Multiplier Output for MULDIV = 000b Internal Oscillator x 2 External Oscillator x 4 External Oscillator x 2 Internal Oscillator x 4 C8051F410/1/2/3 19.4. System Clock Selection The internal oscillator requires little start-up time and may be selected as the system clock immediately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typically 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 external 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 the internal oscillator, external oscillator, smaRTClock oscillator, and Clock Multiplier, as long as the selected clock source is enabled and has settled. SFR Definition 19.5. CLKSEL: Clock Select R R - - Bit7 Bit6 R/W R/W CLKDIV Bit5 Bit4 R R/W - Reserved Bit3 Bit2 R/W R/W CLKSL Bit1 Reset Value 00000000 Bit0 SFR Address: 0xA9 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. CLKSL 00 01 10 11 Selected Clock Internal Oscillator (as determined by the IFCN bits in register OSCICN) External Oscillator Clock Multiplier smaRTClock Oscillator Rev. 1.2 161 C8051F410/1/2/3 Table 19.1. Oscillator Electrical Characteristics –40 to +85 °C unless otherwise specified. Parameter Internal Oscillator Frequency Internal Oscillator Supply Current (from VDD) Minimum Clock Multiplier Input Frequency (FCMmin) 162 Conditions Reset Frequency Min 24 Typ 24.5 Max 25 Units MHz OSCICN.7 = 1 — 400 — μA T = 25 °C — 1.6 — MHz Rev. 1.2 C8051F410/1/2/3 20. smaRTClock (Real Time Clock) C8051F41x devices include a low power smaRTClock Peripheral (Real Time Clock). The smaRTClock has a dedicated 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 battery-backed SRAM. When the backup supply voltage (VRTC-BACKUP) is powered, the smaRTClock peripheral remains fully functional if the core supply 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 smaRTClock 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 Rev. 1.2 163 C8051F410/1/2/3 20.1. smaRTClock Interface The smaRTClock Interface consists of three registers: RTC0KEY, RTC0ADR, and RTC0DAT. These interface registers are located on the CIP-51’s SFR map and provide access to the smaRTClock internal registers listed in Table 20.1. The smaRTClock internal registers can only be accessed indirectly through the smaRTClock 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 Register (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 restrictions, but the key codes must be written in order. If the key codes 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 perform 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 interfere 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 internal 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 operation. A smaRTClock Write operation is initiated by writing to the RTC0DAT register. Below is an example of writing to a smaRTClock internal register. 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 contents of the internal register selected by RTC0ADR to RTC0DAT. The transferred data will remain 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 selects 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 internal register selected by RTC0ADR. Software should set the BUSY bit once at the begin- 164 Rev. 1.2 C8051F410/1/2/3 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 increments after each read or write to a CAPTUREn or ALARMn register. This speeds up the process of setting an alarm or reading the current smaRTClock timer value. Table 20.1. smaRTClock Internal Registers smaRTClock smaRTClock Address Register 0x00 - 0x05 CAPTUREn 0x06 RTC0CN 0x07 RTC0XCN 0x08–0x0D ALARMn 0x0E RAMADDR 0x0F RAMDATA Register Name Description smaRTClock Capture Registers Six Registers used for setting the 47-bit smaRTClock timer or reading its current value. The LSB of CAPTURE0 is not used. smaRTClock Control Controls the operation of the smaRTClock Register State Machine. smaRTClock Oscillator Controls the operation of the smaRTClock Control Register Oscillator. smaRTClock Alarm Six registers used to set or read the 47-bit Registers smaRTClock alarm value. The LSB of ALARM0 is not used. smaRTClock Backup RAM Used as an index to the 64 byte smaRTClock Indirect Address Register backup RAM. smaRTClock Backup RAM Used to read or write the byte pointed to by Indirect Data Register RAMADDR. Rev. 1.2 165 C8051F410/1/2/3 SFR Definition 20.1. RTC0KEY: smaRTClock Lock and Key R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xAE Bits 7–0: RTC0STATE. smaRTClock State Bits Read: 0x00: smaRTClock Interface is locked. 0x01: smaRTClock Interface 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 RTC0STATE = 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. 166 Rev. 1.2 C8051F410/1/2/3 SFR Definition 20.2. RTC0ADR: smaRTClock Address R/W BUSY Bit7 R/W R/W AUTORD VREGEN Bit6 Bit5 R/W R/W SHORT Bit4 R/W R/W R/W RTC0ADDR Bit3 Bit2 Bit1 Reset Value Variable Bit0 SFR Address: 0xAC Bit 7: BUSY: smaRTClock Interface Busy bit. Writing a ‘1’ to this bit initiates a smaRTClock indirect read operation. This bit is automatically 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 Auto Read Enable. 0: BUSY must be written manually for each smaRTClock indirect read operation. 1: The next smaRTClock indirect read operation is initiated when RTC0DAT is read by software. 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 powered from VRTCBACKUP). 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 consumption. Bits 3–0: RTC0ADDR: smaRTClock Address Bits These bits select the smaRTClock internal register that is targeted by reads/writes to RTC0DAT. RTC0ADDR 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 smaRTClock Internal Register CAPTURE0 CAPTURE1 CAPTURE2 CAPTURE3 CAPTURE4 CAPTURE5 RTC0CN RTC0XCN ALARM0 ALARM1 ALARM2 ALARM3 ALARM4 ALARM5 RAMADDR RAMDATA Note: The RTC0ADDR bits increment after each indirect read/write operation that targets a CAPTUREn or ALARMn internal register. Rev. 1.2 167 C8051F410/1/2/3 SFR Definition 20.3. RTC0DAT: smaRTClock Data R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value Variable SFR Address: 0xAD 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 smaRTClock register selected by RTC0ADR. 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 oscillator can be measured with respect to another oscillator using Timer 2 or Timer 3. Section “24.2.3. External/smaRTClock Capture Mode” on page 226 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 161 and Section “18. Port Input/Output” on page 135. 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. Step 2. Step 3. Step 4. Step 5. Step 6. Set smaRTClock to Crystal Mode (XMODE = 1). Optional. Enable Automatic Gain Control (AGCEN = 1). Optional. Enable smaRTClock Bias Doubling (BIASX2 = 1). Enable power to the smaRTClock oscillator circuit (RTC0EN = 1). Poll the smaRTClock Clock Valid Bit (CLKVLD) until the crystal oscillator stabilizes. 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. Self-Oscillate Mode enables a clock, but the generated clock will not be accurate between devices or across voltage or temperature. This clocking option is not intended for accurate timekeeping. 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 approximately 20 kHz, set BIASX2 = 0. For oscillation at approximately 40 kHz, set BIASX2 = 1. Step 3. The oscillator starts oscillating instantaneously. 168 Rev. 1.2 C8051F410/1/2/3 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 smaRTClock oscillator frequency. 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 smaRTClock 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 consumption of smaRTClock; therefore, 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 smaRTClock Missing Clock Detector is enabled, OSCFAIL (RTC0CN.5) is set by hardware 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 smaRTClock Missing Clock Detector should be disabled when making changes to the oscillator settings in RTC0XCN. Rev. 1.2 169 C8051F410/1/2/3 Internal Register Definition 20.4. RTC0CN: smaRTClock Control R/W R/W R/W R/W R/W RTC0EN MCLKEN OSCFAIL RTC0TR RTC0AEN Bit7 Bit6 Bit5 Bit4 Bit3 R/W ALRM Bit2 R/W R/W RTC0SET RTC0CAP Variable Bit1 Bit0 Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: 170 Reset Value smaRTClock Address: 0x06 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. MCLKEN: smaRTClock Missing Clock Detector Enable Bit. When enabled, the smaRTClock missing clock detector sets the OSCFAIL bit if the smaRTClock clock frequency falls below approximately 20 kHz. 0: smaRTClock missing clock detector disabled. 1: smaRTClock missing clock detector enabled. OSCFAIL: smaRTClock Clock Fail Flag. Set by hardware when a missing clock detector timeout occurs. When the smaRTClock Interrupt is enabled, setting this bit causes the CPU to vector to the smaRTClock interrupt service routine. This bit is not automatically cleared by hardware. RTC0TR: smaRTClock Timer Run Control. 0: smaRTClock timer holds its current value. 1: smaRTClock timer increments every smaRTClock clock period. RTC0AEN: smaRTClock Alarm Enable. 0: smaRTClock alarm events disabled. 1: smaRTClock alarm events enabled. ALRM: smaRTClock Alarm Event Flag. Set by hardware when the smaRTClock timer value is greater 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 service routine. This bit is not automatically cleared by hardware. 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. 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. Rev. 1.2 C8051F410/1/2/3 Internal Register Definition 20.5. RTC0XCN: smaRTClock Oscillator Control R/W R/W R/W R R R R R AGCEN XMODE BIASX2 CLKVLD - - - VBATEN Variable Bit0 smaRTClock Address: Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. Reset Value 0x07 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 whether smaRTClock will be used with or without 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 oscillator circuit and should not 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 is powered from the VRTC-BACKUP supply. 20.3. smaRTClock Timer and Alarm Function The smaRTClock timer is a 47-bit counter that, when running (RTC0TR = 1), is incremented every RTCCLK 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. Rev. 1.2 171 C8051F410/1/2/3 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 smaRTClock timer will be found in CAPTURE0.1). 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 smaRTClock Interrupt is enabled, the CIP-51 will vector to the smaRTClock Interrupt 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 from suspend mode on a smaRTClock alarm event. The following steps 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 interrupts. Internal Register Definition 20.6. CAPTUREn: smaRTClock Timer Capture R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 11111111 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. Bits 7–0: CAPTUREn: smaRTClock Set/Capture Value. These 6 registers (CAPTURE5–CAPTURE0) are used to read or set the 47-bit smaRTClock timer. Data is transferred to or from the smaRTClock timer when the RTC0SET or RTC0CAP bits are set. Note: The LSB of CAPTURE0 is not used. The LSB of the 47-bit smaRTClock timer will appear in CAPTURE0.1. 172 Rev. 1.2 C8051F410/1/2/3 Internal Register Definition 20.7. ALARMn: smaRTClock Alarm 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: 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 RTC0DAT. Bits 7–0: ALARMn: smaRTClock Alarm Target. These 6 registers (ALARM5–ALARM0) are used to set an alarm event for the smaRTClock timer. The smaRTClock alarm should be disabled (RTC0AEN=0) when updating these registers. Note: The LSB of ALARM0 is not used. The LSB of the 47-bit smaRTClock timer will be compared against ALARM0.1. 20.4. Backup Regulator and RAM The smaRTClock includes a backup supply regulator that keeps the smaRTClock peripheral fully functional 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 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit0 smaRTClock Address: 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. Bit 7: 0x0E RAMADDR: smaRTClock Battery Backup RAM Address Bits These bits select the smaRTClock Backup RAM byte that is targeted by RAMDATA. This address auto-increments after each read or write of RAMDATA. Rev. 1.2 173 C8051F410/1/2/3 Internal Register Definition 20.9. RAMDATA: smaRTClock Backup RAM Data 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 Note: This register is not an SFR. It can only be accessed indirectly through RTC0ADR and RTC0DAT. Bit 7: smaRTClock Address: 0x0F 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. Reads and writes of RAMDATA load the value at address RAMADDR into RTC0DAT. The following example 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 174 Rev. 1.2 C8051F410/1/2/3 ; 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 Rev. 1.2 175 C8051F410/1/2/3 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 } 176 Rev. 1.2 C8051F410/1/2/3 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 may operate as a master and/or slave, and may function on a bus with multiple masters. 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 Rev. 1.2 177 C8051F410/1/2/3 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 different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus not exceed 300 ns and 1000 ns, respectively. 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 135 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 arbitration. Note that it is not necessary to specify one device as the Master in a system; any device who transmits a START and a slave address becomes the master for the duration of that transfer. 178 Rev. 1.2 C8051F410/1/2/3 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 acknowledge), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation. 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 transaction 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 start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section “21.3.4. SCL High (SMBus Free) Timeout” on page 180). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device always wins, and no data is lost. 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. Rev. 1.2 179 C8051F410/1/2/3 21.3.3. SCL Low Timeout If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communication 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 timeouts. Timer 3 is forced to reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable and re-enable) the SMBus in the event of an SCL low timeout. 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 as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a Master START, the START will be generated following this timeout. Note that a clock source is required for free timeout detection, even in a slave-only implementation. Enabling the Bus Free Timeout is recommended. 21.4. Using the SMBus The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides the following application-independent features: • • • • • • • Byte-wise serial data transfers Clock signal generation on SCL (Master Mode only) and SDA data synchronization Timeout/bus error recognition, as defined by the SMB0CF configuration register START/STOP timing, detection, and generation Bus arbitration Interrupt generation Status information SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting, this interrupt is generated after the ACK cycle so that software may read the received ACK value; when receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing ACK value. See Section “21.5. SMBus Transfer Modes” on page 187 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 184; Table 21.4 provides a quick SMB0CN decoding reference. 180 Rev. 1.2 C8051F410/1/2/3 SMBus configuration options include: • • • • Timeout detection (SCL Low Timeout and/or Bus Free Timeout) SDA setup and hold time extensions Slave event enable/disable Clock source selection These options are selected in the SMB0CF register, as described in Section “21.4.1. SMBus Configuration Register” on page 181. 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 addresses and will not generate any slave interrupts. When the INH bit is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of the current transfer). Table 21.1. SMBus Clock Source Selection SMBCS1 SMBCS0 0 0 0 1 1 0 1 1 SMBus Clock Source Timer 0 Overflow Timer 1 Overflow Timer 2 High Byte Overflow Timer 2 Low Byte Overflow The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or when the Bus Free Timeout detection is enabled. When operating as a master, overflows from the selected source determine the absolute minimum SCL low and high times as defined in Equation 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 covered in Section “24. Timers” on page 216. 1 T HighMin = T LowMin = -----------------------------------------------f ClockSourceOverflow 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), the typical SMBus bit rate is approximated by Equation 21.2. f ClockSourceOverflow BitRate = ----------------------------------------------3 Equation 21.2. Typical SMBus Bit Rate Rev. 1.2 181 C8051F410/1/2/3 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 master will never exceed the limits defined by equation 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 from low-to-high. The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 21.2 shows the minimum 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 operation above 100 kHz, EXTHOLD should be cleared to ‘0’. Table 21.2. Minimum SDA Setup and Hold Times EXTHOLD Minimum SDA Setup Time Tlow - 4 system clocks Minimum SDA Hold Time 0 OR 3 system clocks 1 1 system clock + s/w delay* 11 system clocks 12 system clocks *Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w delay occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w delay is zero. With the SMBTOE bit set, Timer 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 180). The SMBus interface will force Timer 3 to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus. SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see Figure 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 Free Timeout is recommended. 182 Rev. 1.2 C8051F410/1/2/3 SFR Definition 21.1. SMB0CF: SMBus Clock/Configuration R/W R/W R ENSMB INH BUSY Bit7 Bit6 Bit5 R/W R/W R/W R/W EXTHOLD SMBTOE SMBFTE SMBCS1 Bit4 Bit3 Bit2 Bit1 R/W Reset Value SMBCS0 00000000 Bit0 SFR Address: 0xC1 Bit7: ENSMB: SMBus Enable. This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins. 0: SMBus interface disabled. 1: SMBus interface enabled. Bit6: INH: SMBus Slave Inhibit. When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are not affected. 0: SMBus Slave Mode enabled. 1: SMBus Slave Mode inhibited. Bit5: 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 hold times according to Table 21.2. 0: SDA Extended Setup and Hold Times disabled. 1: SDA Extended Setup and Hold Times enabled. Bit3: SMBTOE: SMBus SCL Timeout Detection Enable. This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low. Timer 3 should be programmed to generate interrupts at 25 ms, and the Timer 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 high for more than 10 SMBus clock source periods. Bits1–0: SMBCS1–SMBCS0: SMBus Clock Source Selection. These two bits select the SMBus clock source, which is used to generate the SMBus bit rate. The selected device should be configured according to Equation 21.1. SMBCS1 0 0 1 1 SMBCS0 0 1 0 1 SMBus Clock Source Timer 0 Overflow Timer 1 Overflow Timer 2 High Byte Overflow Timer 2 Low Byte Overflow Rev. 1.2 183 C8051F410/1/2/3 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 are also used to generate START and STOP conditions when operating as a master. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO while in Master Mode will cause the interface to generate a STOP and end the current transfer after the next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be generated. As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be ignored until the next START is detected. The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared. The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or when an arbitration is lost; see Table 21.3 for more details. Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and the bus is stalled until software clears SI. Table 21.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 21.4 for SMBus status decoding using the SMB0CN register. 184 Rev. 1.2 C8051F410/1/2/3 SFR Definition 21.2. SMB0CN: SMBus Control R R MASTER TXMODE Bit7 Bit6 R/W R/W STA STO Bit5 Bit4 R R ACKRQ ARBLOST Bit3 Bit2 R/W R/W Reset Value ACK SI 00000000 Bit1 Bit0 Bit Addressable SFR Address: 0xC0 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: MASTER: SMBus Master/Slave Indicator. This read-only bit indicates when the SMBus is operating as a master. 0: SMBus operating in Slave Mode. 1: SMBus operating in Master Mode. TXMODE: SMBus Transmit Mode Indicator. This read-only bit indicates when the SMBus is operating as a transmitter. 0: SMBus in Receiver Mode. 1: SMBus in Transmitter Mode. STA: SMBus Start Flag. Write: 0: No Start generated. 1: When operating as a master, a START condition is transmitted if the bus is free (If the bus is not free, the START is transmitted after a STOP is received or a timeout is detected). If STA is set by software as an active Master, a repeated START will be generated after the next ACK cycle. Read: 0: No Start or repeated Start detected. 1: Start or repeated Start detected. STO: SMBus Stop Flag. If set by hardware, this bit must be cleared by software. Write: 0: No STOP condition is transmitted. 1: Setting STO to logic 1 causes a STOP condition to be transmitted 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 (if in Master Mode). ACKRQ: SMBus Acknowledge Request This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK bit to be written with the correct ACK response value. ARBLOST: SMBus Arbitration Lost Indicator. This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a transmitter. A lost arbitration while a slave indicates a bus error condition. ACK: SMBus Acknowledge Flag. This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted. 0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). 1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). SI: SMBus Interrupt Flag. This bit is set by hardware under 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. Rev. 1.2 185 C8051F410/1/2/3 Table 21.3. Sources for Hardware Changes to SMB0CN Bit MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI 186 Set by Hardware When: • A START is generated. • START is generated. • SMB0DAT is written before the start of an SMBus frame. • A START followed by an address byte is received. • A STOP is detected while addressed as a slave. • Arbitration is lost due to a detected STOP. • A byte has been received and an ACK response value is needed. • A repeated START is detected as a MASTER when STA is low (unwanted repeated START). • SCL is sensed low while attempting to generate a STOP or repeated START condition. • SDA is sensed low while transmitting a ‘1’ (excluding ACK bits). • The incoming ACK value is low (ACKNOWLEDGE). • 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. Rev. 1.2 Cleared by Hardware When: • A STOP is generated. • Arbitration is lost. • A START is detected. • Arbitration is lost. • SMB0DAT is not written before the start of an SMBus frame. • Must be cleared by software. • A pending STOP is generated. • If STO is set by hardware, it must be cleared by software. • After each ACK cycle. • Each time SI is cleared. • The incoming ACK value is high (NOT ACKNOWLEDGE). • Must be cleared by software. C8051F410/1/2/3 21.4.3. Data Register The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software may safely read or write to the data register when the SI flag is set. Software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0, as the interface may be in the process of shifting a byte of data into or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, 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 R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0xC2 Bits7–0: SMB0DAT: SMBus Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long as the SI flag is set. When the SI flag is not set, the system may be in the process of shifting data in/out and the CPU should not attempt to access this register. 21.5. SMBus Transfer Modes The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter. 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 transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. Rev. 1.2 187 C8051F410/1/2/3 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 direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial data. 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 generates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written while an active Master Receiver. Figure 21.6 shows a typical Master Receiver sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode. Figure 21.6. Typical Master Receiver Sequence 188 Rev. 1.2 C8051F410/1/2/3 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 interface enters Slave Receiver Mode when a START followed by a slave address and direction bit (WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave Transmitter Mode if SMB0DAT is written while an active Slave Receiver. 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 Rev. 1.2 189 C8051F410/1/2/3 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 enters Slave Receiver Mode (to receive the slave address) when a START followed by a slave address and direction bit (READ in this case) is received. Upon entering Slave 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 transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 21.8 shows a typical Slave Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. 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. Highlighted responses are allowed but do not conform to the SMBus specification. 190 Rev. 1.2 C8051F410/1/2/3 Table 21.4. SMBus Status Decoding Values Written 0 0 1100 0 1000 1 0 0 Load slave address + R/W into SMB0DAT. Set STA to restart transfer. A master data or address byte 0 was transmitted; NACK received. Abort transfer. Load next data byte into SMB0DAT. End transfer with STOP. End transfer with STOP and A master data or address byte 1 start another transfer. was transmitted; ACK received. Send repeated START. Switch to Master Receiver Mode (clear SI without writing new data to SMB0DAT). Acknowledge received byte; Read SMB0DAT. Send NACK to indicate last byte, and send STOP. Send NACK to indicate last byte, and send STOP followed by START. Send ACK followed by repeated START. A master data byte was received; Send NACK to indicate last X ACK requested. byte, and send repeated START. Send ACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). Send NACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). X A master START was generated. Rev. 1.2 ACK ARBLOST 0 Typical Response Options STO ACKRQ 0 ACK Status Vector 1110 Current SMbus State STA Master Receiver Master Transmitter Mode Values Read 0 0 X 1 0 0 1 X X 0 0 X 0 1 X 1 1 X 1 0 X 0 0 X 0 0 1 0 1 0 1 1 0 1 0 1 1 0 0 0 0 1 0 0 0 191 C8051F410/1/2/3 Table 21.4. SMBus Status Decoding (Continued) Values Written 0 0 1 0 X 1 0 Slave Receiver 1 0010 0001 1 X 0 1 X 1 1 X 0 0 X 0 1 X 1 0 X 0000 1 192 1 X Clear STO. Acknowledge received address. Do not acknowledge received address. Acknowledge received address. Lost arbitration as master; slave Do not acknowledge address received; ACK received address. requested. Reschedule failed transfer; do not acknowledge received address. Lost arbitration while attempting a Abort failed transfer. repeated START. Reschedule failed transfer. Lost arbitration while attempting a No action required (transfer STOP. complete/aborted). A STOP was detected while addressed as a Slave Transmitter Clear STO. or Slave Receiver. Lost arbitration due to a detected Abort transfer. STOP. Reschedule failed transfer. Acknowledge received byte; A slave byte was received; ACK Read SMB0DAT. requested. Do not acknowledge received byte. Lost arbitration while transmitting Abort failed transfer. a data byte as master. Reschedule failed transfer. A slave address was received; X ACK requested. 0010 No action required (expecting STOP condition). Load SMB0DAT with next data byte to transmit. No action required (expecting Master to end transfer). Rev. 1.2 ACK 0 A slave byte was transmitted; NACK received. A slave byte was transmitted; 1 ACK received. A Slave byte was transmitted; X error detected. An illegal STOP or bus error was X detected while a Slave Transmission was in progress. 0 Typical Response Options STO 0 ACK 0 Current SMbus State STA 0101 ARBLOST Status Vector 0100 ACKRQ Slave Transmitter Mode Values Read 0 0 X 0 0 X 0 0 X 0 0 X 0 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 X X 0 0 0 0 0 X 0 1 0 0 X X 0 0 1 0 0 0 0 1 0 0 0 0 C8051F410/1/2/3 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 standard baud rates (details in Section “22.1. Enhanced Baud Rate Generation” on page 194). Received data buffering allows UART0 to start reception of a second incoming data byte before software has finished reading the previous data byte. UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0). The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0 always access the Transmit register. Reads of SBUF0 always access the buffered Receive register; it is not possible to read data from the Transmit register. With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive complete). Figure 22.1. UART0 Block Diagram Rev. 1.2 193 C8051F410/1/2/3 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 useraccessible. 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 218). The Timer 1 reload value should be set so that overflows will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an external input T1. The UART0 baud rate is determined by Equation 22.1-A and Equation 22.1-B. A) UartBaudRate = 1---  T1_Overflow_Rate 2 B) T1 CLK T1_Overflow_Rate = ------------------------256 – TH1 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). Timer 1 clock frequency is selected as described in Section “24. Timers” on page 216. 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. 194 Rev. 1.2 C8051F410/1/2/3 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 start bit, eight data bits (LSB first), and one stop bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2). Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to 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 overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits are lost. If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 is set. Figure 22.4. 8-Bit UART Timing Diagram Rev. 1.2 195 C8051F410/1/2/3 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 programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80 (SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the stop bit is ignored. Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to ‘1’. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: (1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to ‘1’. If the above conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to ‘1’. A UART0 interrupt will occur if enabled when either TI0 or RI0 is set to ‘1’. 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 data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address byte has been received. In the UART interrupt handler, software will compare the received address with the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte. Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s). 196 Rev. 1.2 C8051F410/1/2/3 Figure 22.6. UART Multi-Processor Mode Interconnect Diagram Rev. 1.2 197 C8051F410/1/2/3 SFR Definition 22.1. SCON0: Serial Port 0 Control 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 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 198 S0MODE: Serial Port 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. UNUSED. Read = 1b. Write = don’t care. MCE0: Multiprocessor Communication Enable. The function of this bit is dependent on the Serial Port 0 Operation Mode. 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. REN0: Receive Enable. This bit enables/disables the UART receiver. 0: UART0 reception disabled. 1: UART0 reception enabled. TB80: Ninth Transmission Bit. The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It is not used in 8-bit UART Mode. Set or cleared by software as required. RB80: Ninth Receive Bit. RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th data bit in Mode 1. TI0: Transmit Interrupt Flag. Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. RI0: Receive Interrupt Flag. Set to ‘1’ by hardware when a byte of data has been received by UART0 (set at the STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. Rev. 1.2 C8051F410/1/2/3 SFR Definition 22.2. SBUF0: Serial (UART0) Port Data Buffer R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0x99 Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7-0 (MSB-LSB) This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch. Rev. 1.2 199 C8051F410/1/2/3 SYSCLK from Internal Osc. Table 22.1. Timer Settings for Standard Baud Rates Using the Internal Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 Frequency: 24.5 MHz OscillaSCA1-SCA0 Timer 1 Baud Rate Timer Clock tor Divide (pre-scale T1M* Reload % Error Source Factor select)* Value (hex) -0.32% 106 SYSCLK XX 1 0xCB -0.32% 212 SYSCLK XX 1 0x96 0.15% 426 SYSCLK XX 1 0x2B -0.32% 848 SYSCLK / 4 01 0 0x96 0.15% 1704 SYSCLK / 12 00 0 0xB9 -0.32% 2544 SYSCLK / 12 00 0 0x96 -0.32% 10176 SYSCLK / 48 10 0 0x96 0.15% 20448 SYSCLK / 48 10 0 0x2B X = Don’t care *Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1. SYSCLK from SYSCLK from Internal Osc. External Osc. Table 22.2. Timer Settings for Standard Baud Rates Using an External 25.0 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 57600 28800 14400 9600 Baud Rate % Error -0.47% 0.45% -0.01% 0.45% -0.01% 0.15% 0.45% -0.01% -0.47% -0.47% 0.45% 0.15% Frequency: 25.0 MHz OscillaSCA1-SCA0 Timer Clock tor Divide (pre-scale Source Factor select)* 108 SYSCLK XX 218 SYSCLK XX 434 SYSCLK XX 872 SYSCLK / 4 01 1736 SYSCLK / 4 01 2608 EXTCLK / 8 11 10464 SYSCLK / 48 10 20832 SYSCLK / 48 10 432 EXTCLK / 8 11 864 EXTCLK / 8 11 1744 EXTCLK / 8 11 2608 EXTCLK / 8 11 1 1 1 0 0 0 0 0 0 0 0 Timer 1 Reload Value (hex) 0xCA 0x93 0x27 0x93 0x27 0x5D 0x93 0x27 0xE5 0xCA 0x93 0 0x5D T1M* X = Don’t care *Note: SCA1-SCA0 and T1M bit definitions can be found in Section 24.1. 200 Rev. 1.2 C8051F410/1/2/3 SYSCLK from Internal Osc. SYSCLK from External Osc. Table 22.3. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 22.1184 MHz OscillaSCA1-SCA0 Timer 1 Baud Rate Timer Clock tor Divide (pre-scale T1M* Reload % Error Source Factor select)* Value (hex) 0.00% 96 SYSCLK XX 1 0xD0 0.00% 192 SYSCLK XX 1 0xA0 0.00% 384 SYSCLK XX 1 0x40 0.00% 768 SYSCLK / 12 00 0 0xE0 0.00% 1536 SYSCLK / 12 00 0 0xC0 0.00% 2304 SYSCLK / 12 00 0 0xA0 0.00% 9216 SYSCLK / 48 10 0 0xA0 0.00% 18432 SYSCLK / 48 10 0 0x40 0.00% 96 EXTCLK / 8 11 0 0xFA 0.00% 192 EXTCLK / 8 11 0 0xF4 0.00% 384 EXTCLK / 8 11 0 0xE8 0.00% 768 EXTCLK / 8 11 0 0xD0 0.00% 1536 EXTCLK / 8 11 0 0xA0 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. SYSCLK from Internal Osc. SYSCLK from External Osc. Table 22.4. Timer Settings for Standard Baud Rates Using an External 18.432 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 18.432 MHz OscillaSCA1-SCA0 Timer 1 Baud Rate Timer Clock tor Divide (pre-scale T1M* Reload % Error Source Factor select)* Value (hex) 0.00% 80 SYSCLK XX 1 0xD8 0.00% 160 SYSCLK XX 1 0xB0 0.00% 320 SYSCLK XX 1 0x60 0.00% 640 SYSCLK / 4 01 0 0xB0 0.00% 1280 SYSCLK / 4 01 0 0x60 0.00% 1920 SYSCLK / 12 00 0 0xB0 0.00% 7680 SYSCLK / 48 10 0 0xB0 0.00% 15360 SYSCLK / 48 10 0 0x60 0.00% 80 EXTCLK / 8 11 0 0xFB 0.00% 160 EXTCLK / 8 11 0 0xF6 0.00% 320 EXTCLK / 8 11 0 0xEC 0.00% 640 EXTCLK / 8 11 0 0xD8 0.00% 1280 EXTCLK / 8 11 0 0xB0 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. Rev. 1.2 201 C8051F410/1/2/3 SYSCLK from Internal Osc. SYSCLK from External Osc. Table 22.5. Timer Settings for Standard Baud Rates Using an External 11.0592 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 11.0592 MHz OscillaSCA1-SCA0 Timer 1 Baud Rate Timer Clock tor Divide (pre-scale T1M* Reload % Error Source Factor select)* Value (hex) 0.00% 48 SYSCLK XX 1 0xE8 0.00% 96 SYSCLK XX 1 0xD0 0.00% 192 SYSCLK XX 1 0xA0 0.00% 384 SYSCLK XX 1 0x40 0.00% 768 SYSCLK / 12 00 0 0xE0 0.00% 1152 SYSCLK / 12 00 0 0xD0 0.00% 4608 SYSCLK / 12 00 0 0x40 0.00% 9216 SYSCLK / 48 10 0 0xA0 0.00% 48 EXTCLK / 8 11 0 0xFD 0.00% 96 EXTCLK / 8 11 0 0xFA 0.00% 192 EXTCLK / 8 11 0 0xF4 0.00% 384 EXTCLK / 8 11 0 0xE8 0.00% 768 EXTCLK / 8 11 0 0xD0 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. SYSCLK from Internal Osc. SYSCLK from External Osc. Table 22.6. Timer Settings for Standard Baud Rates Using an External 3.6864 MHz Oscillator 202 Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 3.6864 MHz OscillaSCA1-SCA0 Timer 1 Baud Rate Timer Clock tor Divide (pre-scale T1M* Reload % Error Source Factor select)* Value (hex) 0.00% 16 SYSCLK XX 1 0xF8 0.00% 32 SYSCLK XX 1 0xF0 0.00% 64 SYSCLK XX 1 0xE0 0.00% 128 SYSCLK XX 1 0xC0 0.00% 256 SYSCLK XX 1 0x80 0.00% 384 SYSCLK XX 1 0x40 0.00% 1536 SYSCLK / 12 00 0 0xC0 0.00% 3072 SYSCLK / 12 00 0 0x80 0.00% 16 EXTCLK / 8 11 0 0xFF 0.00% 32 EXTCLK / 8 11 0 0xFE 0.00% 64 EXTCLK / 8 11 0 0xFC 0.00% 128 EXTCLK / 8 11 0 0xF8 0.00% 256 EXTCLK / 8 11 0 0xF0 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. Rev. 1.2 C8051F410/1/2/3 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 masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode. Figure 23.1. SPI Block Diagram Rev. 1.2 203 C8051F410/1/2/3 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 to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating 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 operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register. 23.1.3. Serial Clock (SCK) The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates 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 bits affects the pinout of the device. When in 3-wire master or 3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will be mapped to a pin on the device. See Section “18. Port Input/Output” on page 135 for general purpose port I/O and crossbar information. 204 Rev. 1.2 C8051F410/1/2/3 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 buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers 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 receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (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-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-master 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-master mode. 3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this mode, NSS is not used and is not mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 23.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an output pin and can be used as a slave-select signal for a single SPI device. In this mode, the output value of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 23.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices. Rev. 1.2 205 C8051F410/1/2/3 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 signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted into the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or current) SPI transfer. 206 Rev. 1.2 C8051F410/1/2/3 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 logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal 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 only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and reenabling SPI0 with the SPIEN bit. Figure 23.3 shows a connection diagram between a slave device in 3wire slave mode and a master 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 set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0 modes. 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 pulled low. When a Mode Fault occurs, the MSTEN 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 byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost. 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 rising edge or a falling edge. 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 data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz, Rev. 1.2 207 C8051F410/1/2/3 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 4wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less than 1/10 the system clock frequency. In the special case where the master only wants to transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency. This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s system clock. 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. 208 Rev. 1.2 C8051F410/1/2/3 SFR Definition 23.1. SPI0CFG: SPI0 Configuration 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 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: Bit0 SFR Address: 0xA1 SPIBSY: SPI Busy (read only). This bit is set to logic 1 when a SPI transfer is in progress (Master or Slave Mode). MSTEN: Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. 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.* 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. 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. 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. 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 shift register, and there is no new information available to read from the transmit buffer or write to the receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from the transmit buffer or by a transition on SCK. NOTE: SRMT = 1 when in Master Mode. 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 available in the receive buffer that has 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. Rev. 1.2 209 C8051F410/1/2/3 SFR Definition 23.2. SPI0CN: SPI0 Control R/W R/W R/W SPIF WCOL MODF Bit7 Bit6 Bit5 R/W R/W R/W RXOVRN NSSMD1 NSSMD0 Bit4 Bit3 Bit 7: Bit2 R R/W Reset Value TXBMT SPIEN 00000110 Bit1 Bit Addressable SFR Address: 0xF8 Bit0 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 write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. It must be cleared by software. 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 automatically 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 buffer 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 automatically 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 page 205 and Section “23.3. SPI0 Slave Mode Operation” on page 206). 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 mapped as an output 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 transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer. Bit 0: SPIEN: SPI0 Enable. This bit enables/disables the SPI. 0: SPI disabled. 1: SPI enabled. 210 Rev. 1.2 C8051F410/1/2/3 SFR Definition 23.3. SPI0CKR: SPI0 Clock Rate 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 Bits 7–0: SCR7–SCR0: SPI0 Clock Rate. These bits determine the frequency of the SCK output when the SPI0 module is configured for master mode operation. The SCK clock frequency is a divided version of the system clock, and is given in the following equation, where SYSCLK is the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR register. SYSCLK f SCK = ------------------------------------------------2   SPI 0CKR + 1  for 0