C8051F040-TB

C8051F040/1/2/3/4/5/6/7 8K ISP FLASH MCU Family Analog Peripherals - 10 or 12-Bit SAR ADC • - - • • • • • • • 12-bit (C8051F040/1) or 10-bit (C8051F042/3/4/5/6/7) resolution ± 1 LSB INL, guaranteed no missing codes Programmable throughput up to 100 ksps 13 External Inputs; single-ended or differential SW programmable high voltage difference amplifier Programmable amplifier gain: 16, 8, 4, 2, 1, 0.5 Data-dependent windowed interrupt generator Built-in temperature sensor 8-bit SAR ADC (C8051F040/1/2/3 only) • • • Programmable throughput up to 500 ksps 8 External Inputs, single-ended or differential Programmable amplifier gain: 4, 2, 1, 0.5 Two 12-bit DACs (C8051F040/1/2/3 only) • - High-Speed 8051 μC Core - Pipelined instruction architecture; executes 70% of Can synchronize outputs to timers for jitter-free waveform generation Three Analog Comparators • - - intrusive in-circuit/in-system debugging Provides breakpoints, single-stepping, watchpoints, stack monitor; inspect/modify memory and registers Superior performance to emulation systems using ICE-chips, target pods, and sockets IEEE1149.1 compliant boundary scan Complete development kit Rev. 1.6 5/16 or 32 kB (C8051F046/7) Flash; in-system programmable in 512-byte sectors External 64 kB data memory interface (programmable multiplexed or non-multiplexed modes) Digital Peripherals - 8 byte-wide port I/O (C8051F040/2/4/6); 5 V tolerant - 4 byte-wide port I/O (C8051F041/3/5/7); 5 V tolerant - Bosch Controller Area Network (CAN 2.0B), hard- Programmable hysteresis/response time - Voltage Reference - Precision VDD Monitor/Brown-Out Detector On-Chip JTAG Debug & Boundary Scan - On-chip debug circuitry facilitates full- speed, non- instruction set in 1 or 2 system clocks - Up to 25 MIPS throughput with 25 MHz clock - 20 vectored interrupt sources Memory - 4352 bytes internal data RAM (4 k + 256) - 64 kB (C8051F040/1/2/3/4/5) - ware SMBus™ (I2C™ Compatible), SPI™, and two UART serial ports available concurrently Programmable 16-bit counter/timer array with 6 capture/compare modules 5 general purpose 16-bit counter/timers Dedicated watch-dog timer; bi-directional reset pin Clock Sources - Internal calibrated programmable oscillator: 3 to 24.5 MHz - External oscillator: crystal, RC, C, or clock - Real-time clock mode using Timer 2, 3, 4, or PCA Supply Voltage: 2.7 to 3.6 V - Multiple power saving sleep and shutdown modes 100-Pin and 64-Pin TQFP Packages Available - Temperature Range: –40 to +85 °C Copyright © 2016 by Silicon Laboratories C8051F040/1/2/3/4/5/6/7 C8051F040/1/2/3/4/5/6/7 2 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table of Contents 1. System Overview.................................................................................................... 19 1.1. CIP-51™ Microcontroller Core.......................................................................... 25 1.1.1. Fully 8051 Compatible.............................................................................. 25 1.1.2. Improved Throughput ............................................................................... 25 1.1.3. Additional Features .................................................................................. 26 1.2. On-Chip Memory............................................................................................... 27 1.3. JTAG Debug and Boundary Scan..................................................................... 28 1.4. Programmable Digital I/O and Crossbar ........................................................... 29 1.5. Programmable Counter Array ........................................................................... 30 1.6. Controller Area Network.................................................................................... 31 1.7. Serial Ports ....................................................................................................... 31 1.8. 12/10-Bit Analog to Digital Converter................................................................ 32 1.9. 8-Bit Analog to Digital Converter (C8051F040/1/2/3 Only) ............................... 33 1.10.Comparators and DACs ................................................................................... 34 2. Absolute Maximum Ratings .................................................................................. 35 3. Global DC Electrical Characteristic ...................................................................... 36 4. Pinout and Package Definitions............................................................................ 37 5. 12-Bit ADC (ADC0, C8051F040/1 Only)................................................................. 47 5.1. Analog Multiplexer and PGA............................................................................. 47 5.1.1. Analog Input Configuration....................................................................... 48 5.2. High-Voltage Difference Amplifier..................................................................... 52 5.3. ADC Modes of Operation.................................................................................. 54 5.3.1. Starting a Conversion............................................................................... 54 5.3.2. Tracking Modes........................................................................................ 54 5.3.3. Settling Time Requirements ..................................................................... 56 5.4. ADC0 Programmable Window Detector ........................................................... 62 6. 10-Bit ADC (ADC0, C8051F042/3/4/5/6/7 Only)..................................................... 69 6.1. Analog Multiplexer and PGA............................................................................. 69 6.1.1. Analog Input Configuration....................................................................... 70 6.2. High-Voltage Difference Amplifier..................................................................... 74 6.3. ADC Modes of Operation.................................................................................. 76 6.3.1. Starting a Conversion............................................................................... 76 6.3.2. Tracking Modes........................................................................................ 76 6.3.3. Settling Time Requirements ..................................................................... 78 6.4. ADC0 Programmable Window Detector ........................................................... 84 7. 8-Bit ADC (ADC2, C8051F040/1/2/3 Only)............................................................. 91 7.1. Analog Multiplexer and PGA............................................................................. 91 7.2. ADC2 Modes of Operation................................................................................ 92 7.2.1. Starting a Conversion............................................................................... 92 7.2.2. Tracking Modes........................................................................................ 92 7.2.3. Settling Time Requirements ..................................................................... 94 7.3. ADC2 Programmable Window Detector ......................................................... 100 7.3.1. Window Detector in Single-Ended Mode................................................ 100 Rev. 1.6 3 C8051F040/1/2/3/4/5/6/7 7.3.2. Window Detector in Differential Mode .................................................... 102 8. DACs, 12-Bit Voltage Mode (C8051F040/1/2/3 Only) ......................................... 105 8.1. DAC Output Scheduling.................................................................................. 106 8.1.1. Update Output On-Demand ................................................................... 106 8.1.2. Update Output Based on Timer Overflow .............................................. 106 8.2. DAC Output Scaling/Justification .................................................................... 106 9. Voltage Reference (C8051F040/2/4/6) ................................................................. 113 10. Voltage Reference (C8051F041/3/5/7) ................................................................. 117 11. Comparators ......................................................................................................... 121 11.1.Comparator Inputs.......................................................................................... 123 12. CIP-51 Microcontroller ......................................................................................... 127 12.1.Instruction Set................................................................................................. 129 12.1.1.Instruction and CPU Timing ................................................................... 129 12.1.2.MOVX Instruction and Program Memory ............................................... 129 12.2.Memory Organization ..................................................................................... 133 12.2.1.Program Memory ................................................................................... 133 12.2.2.Data Memory.......................................................................................... 134 12.2.3.General Purpose Registers.................................................................... 134 12.2.4.Bit Addressable Locations...................................................................... 134 12.2.5.Stack ..................................................................................................... 134 12.2.6.Special Function Registers .................................................................... 135 12.2.7.Register Descriptions ............................................................................. 150 12.3.Interrupt Handler............................................................................................. 153 12.3.1.MCU Interrupt Sources and Vectors ...................................................... 153 12.3.2.External Interrupts.................................................................................. 154 12.3.3.Interrupt Priorities................................................................................... 156 12.3.4.Interrupt Latency .................................................................................... 156 12.3.5.Interrupt Register Descriptions............................................................... 156 12.4.Power Management Modes............................................................................ 163 12.4.1.Idle Mode ............................................................................................... 163 12.4.2.Stop Mode.............................................................................................. 164 13. Reset Sources....................................................................................................... 165 13.1.Power-On Reset ............................................................................................. 166 13.2.Power-Fail Reset ............................................................................................ 166 13.3.External Reset ................................................................................................ 166 13.4.Missing Clock Detector Reset ........................................................................ 167 13.5.Comparator0 Reset ........................................................................................ 167 13.6.External CNVSTR0 Pin Reset ........................................................................ 167 13.7.Watchdog Timer Reset................................................................................... 167 13.7.1.Enable/Reset WDT ................................................................................ 168 13.7.2.Disable WDT .......................................................................................... 168 13.7.3.Disable WDT Lockout ............................................................................ 168 13.7.4.Setting WDT Interval .............................................................................. 168 14. Oscillators ............................................................................................................. 173 14.1.Programmable Internal Oscillator ................................................................... 173 4 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 14.2.External Oscillator Drive Circuit...................................................................... 175 14.3.System Clock Selection.................................................................................. 175 14.4.External Crystal Example ............................................................................... 177 14.5.External RC Example ..................................................................................... 178 14.6.External Capacitor Example ........................................................................... 178 15. Flash Memory ....................................................................................................... 179 15.1.Programming The Flash Memory ................................................................... 179 15.2.Non-volatile Data Storage .............................................................................. 180 15.3.Security Options ............................................................................................. 180 15.3.1.Summary of Flash Security Options....................................................... 183 16. External Data Memory Interface and On-Chip XRAM........................................ 187 16.1.Accessing XRAM............................................................................................ 187 16.1.1.16-Bit MOVX Example ........................................................................... 187 16.1.2.8-Bit MOVX Example ............................................................................. 187 16.2.Configuring the External Memory Interface .................................................... 188 16.3.Port Selection and Configuration.................................................................... 188 16.4.Multiplexed and Non-multiplexed Selection.................................................... 191 16.4.1.Multiplexed Configuration....................................................................... 191 16.4.2.Non-multiplexed Configuration............................................................... 192 16.5.Memory Mode Selection................................................................................. 193 16.5.1.Internal XRAM Only ............................................................................... 193 16.5.2.Split Mode without Bank Select.............................................................. 193 16.5.3.Split Mode with Bank Select................................................................... 194 16.5.4.External Only.......................................................................................... 194 16.6.Timing .......................................................................................................... 194 16.6.1.Non-multiplexed Mode ........................................................................... 196 16.6.2.Multiplexed Mode ................................................................................... 199 17. Port Input/Output.................................................................................................. 203 17.1.Ports 0 through 3 and the Priority Crossbar Decoder..................................... 204 17.1.1.Crossbar Pin Assignment and Allocation ............................................... 205 17.1.2.Configuring the Output Modes of the Port Pins...................................... 206 17.1.3.Configuring Port Pins as Digital Inputs................................................... 206 17.1.4.Weak Pullups ......................................................................................... 207 17.1.5.Configuring Port 1, 2, and 3 Pins as Analog Inputs ............................... 207 17.1.6.External Memory Interface Pin Assignments ......................................... 208 17.1.7.Crossbar Pin Assignment Example........................................................ 210 17.2.Ports 4 through 7 ............................................................................................ 220 17.2.1.Configuring Ports Which are Not Pinned Out......................................... 221 17.2.2.Configuring the Output Modes of the Port Pins...................................... 221 17.2.3.Configuring Port Pins as Digital Inputs................................................... 221 17.2.4.Weak Pullups ......................................................................................... 221 17.2.5.External Memory Interface ..................................................................... 221 18. Controller Area Network (CAN0) ......................................................................... 227 18.1.Bosch CAN Controller Operation.................................................................... 228 18.1.1.CAN Controller Timing ........................................................................... 229 Rev. 1.6 5 C8051F040/1/2/3/4/5/6/7 18.1.2.Example Timing Calculation for 1 Mbit/Sec Communication ................. 229 18.2.CAN Registers................................................................................................ 231 18.2.1.CAN Controller Protocol Registers......................................................... 231 18.2.2.Message Object Interface Registers ...................................................... 231 18.2.3.Message Handler Registers................................................................... 232 18.2.4.CIP-51 MCU Special Function Registers ............................................... 232 18.2.5.Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers . 232 18.2.6.CAN0ADR Autoincrement Feature ........................................................ 232 19. System Management BUS/I2C BUS (SMBUS0) .................................................. 239 19.1.Supporting Documents ................................................................................... 240 19.2.SMBus Protocol.............................................................................................. 241 19.2.1.Arbitration............................................................................................... 241 19.2.2.Clock Low Extension.............................................................................. 242 19.2.3.SCL Low Timeout................................................................................... 242 19.2.4.SCL High (SMBus Free) Timeout .......................................................... 242 19.3.SMBus Transfer Modes.................................................................................. 242 19.3.1.Master Transmitter Mode ....................................................................... 242 19.3.2.Master Receiver Mode ........................................................................... 243 19.3.3.Slave Transmitter Mode ......................................................................... 243 19.3.4.Slave Receiver Mode ............................................................................. 244 19.4.SMBus Special Function Registers ................................................................ 245 19.4.1.Control Register ..................................................................................... 245 19.4.2.Clock Rate Register ............................................................................... 248 19.4.3.Data Register ......................................................................................... 249 19.4.4.Address Register.................................................................................... 249 19.4.5.Status Register....................................................................................... 250 20. Enhanced Serial Peripheral Interface (SPI0)...................................................... 255 20.1.Signal Descriptions......................................................................................... 256 20.1.1.Master Out, Slave In (MOSI).................................................................. 256 20.1.2.Master In, Slave Out (MISO).................................................................. 256 20.1.3.Serial Clock (SCK) ................................................................................. 256 20.1.4.Slave Select (NSS) ................................................................................ 256 20.2.SPI0 Master Mode Operation ......................................................................... 257 20.3.SPI0 Slave Mode Operation ........................................................................... 259 20.4.SPI0 Interrupt Sources ................................................................................... 259 20.5.Serial Clock Timing......................................................................................... 260 20.6.SPI Special Function Registers ...................................................................... 261 21. UART0.................................................................................................................... 265 21.1.UART0 Operational Modes ............................................................................ 266 21.1.1.Mode 0: Synchronous Mode .................................................................. 266 21.1.2.Mode 1: 8-Bit UART, Variable Baud Rate.............................................. 267 21.1.3.Mode 2: 9-Bit UART, Fixed Baud Rate .................................................. 269 21.1.4.Mode 3: 9-Bit UART, Variable Baud Rate.............................................. 270 21.2.Multiprocessor Communications .................................................................... 270 6 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 21.3.Configuration of a Masked Address ............................................................... 271 21.4.Broadcast Addressing .................................................................................... 271 21.5.Frame and Transmission Error Detection....................................................... 272 22. UART1.................................................................................................................... 277 22.1.Enhanced Baud Rate Generation................................................................... 278 22.2.Operational Modes ......................................................................................... 279 22.2.1.8-Bit UART ............................................................................................. 279 22.2.2.9-Bit UART ............................................................................................. 280 22.3.Multiprocessor Communications .................................................................... 281 23. Timers.................................................................................................................... 289 23.1.Timer 0 and Timer 1 ....................................................................................... 289 23.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 289 23.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 290 23.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 291 23.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 292 23.2.Timer 2, Timer 3, and Timer 4 ........................................................................ 297 23.2.1.Configuring Timer 2, 3, and 4 to Count Down........................................ 297 23.2.2.Capture Mode ........................................................................................ 298 23.2.3.Auto-Reload Mode ................................................................................. 299 23.2.4.Toggle Output Mode .............................................................................. 300 24. Programmable Counter Array ............................................................................. 305 24.1.PCA Counter/Timer ........................................................................................ 306 24.2.Capture/Compare Modules ............................................................................ 307 24.2.1.Edge-triggered Capture Mode................................................................ 308 24.2.2.Software Timer (Compare) Mode........................................................... 309 24.2.3.High-Speed Output Mode ...................................................................... 310 24.2.4.Frequency Output Mode ........................................................................ 311 24.2.5.8-Bit Pulse Width Modulator Mode......................................................... 312 24.2.6.16-Bit Pulse Width Modulator Mode....................................................... 313 24.3.Register Descriptions for PCA0...................................................................... 314 25. JTAG (IEEE 1149.1) .............................................................................................. 319 25.1.Boundary Scan ............................................................................................... 320 25.1.1.EXTEST Instruction................................................................................ 321 25.1.2.SAMPLE Instruction ............................................................................... 321 25.1.3.BYPASS Instruction ............................................................................... 321 25.1.4.IDCODE Instruction................................................................................ 321 25.2.Flash Programming Commands..................................................................... 323 25.3.Debug Support ............................................................................................... 326 Document Change List............................................................................................. 327 Contact Information.................................................................................................. 328 Rev. 1.6 7 C8051F040/1/2/3/4/5/6/7 NOTES: 8 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 List of Figures 1. System Overview Figure 1.1. C8051F040/2 Block Diagram ................................................................. 21 Figure 1.2. C8051F041/3 Block Diagram ................................................................. 22 Figure 1.3. C8051F044/6 Block Diagram ................................................................. 23 Figure 1.4. C8051F045/7 Block Diagram ................................................................. 24 Figure 1.5. Comparison of Peak MCU Execution Speeds ....................................... 25 Figure 1.6. On-Board Clock and Reset .................................................................... 26 Figure 1.7. On-Chip Memory Map............................................................................ 27 Figure 1.8. Development/In-System Debug Diagram............................................... 28 Figure 1.9. Digital Crossbar Diagram ....................................................................... 29 Figure 1.10. PCA Block Diagram.............................................................................. 30 Figure 1.11. CAN Controller Diagram....................................................................... 31 Figure 1.12. 10/12-Bit ADC Block Diagram .............................................................. 32 Figure 1.13. 8-Bit ADC Diagram............................................................................... 33 Figure 1.14. Comparator and DAC Diagram ............................................................ 34 2. Absolute Maximum Ratings 3. Global DC Electrical Characteristic 4. Pinout and Package Definitions Figure 4.1. TQFP-100 Pinout Diagram..................................................................... 43 Figure 4.2. TQFP-100 Package Drawing ................................................................. 44 Figure 4.3. TQFP-64 Pinout Diagram....................................................................... 45 Figure 4.4. TQFP-64 Package Drawing ................................................................... 46 5. 12-Bit ADC (ADC0, C8051F040/1 Only) Figure 5.1. 12-Bit ADC0 Functional Block Diagram ................................................. 47 Figure 5.2. Analog Input Diagram ............................................................................ 48 Figure 5.3. High Voltage Difference Amplifier Functional Diagram .......................... 52 Figure 5.4. 12-Bit ADC Track and Conversion Example Timing .............................. 55 Figure 5.5. ADC0 Equivalent Input Circuits.............................................................. 56 Figure 5.6. Temperature Sensor Transfer Function ................................................. 57 Figure 5.7. ADC0 Data Word Example .................................................................... 61 Figure 5.8. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data ........................................................ 63 Figure 5.9. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential Data............................................................. 64 Figure 5.10. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data........................................................... 65 Figure 5.11. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data . 66 6. 10-Bit ADC (ADC0, C8051F042/3/4/5/6/7 Only) Figure 6.1. 10-Bit ADC0 Functional Block Diagram ................................................. 69 Figure 6.2. Analog Input Diagram ............................................................................ 70 Figure 6.3. High Voltage Difference Amplifier Functional Diagram .......................... 74 Figure 6.4. 10-Bit ADC Track and Conversion Example Timing .............................. 77 Rev. 1.6 9 C8051F040/1/2/3/4/5/6/7 Figure 6.5. Figure 6.6. Figure 6.7. Figure 6.8. ADC0 Equivalent Input Circuits.............................................................. 78 Temperature Sensor Transfer Function ................................................. 79 ADC0 Data Word Example .................................................................... 83 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data ........................................................ 85 Figure 6.9. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential Data............................................................. 86 Figure 6.10. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data........................................................... 87 Figure 6.11. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data . 88 7. 8-Bit ADC (ADC2, C8051F040/1/2/3 Only) Figure 7.1. ADC2 Functional Block Diagram............................................................ 91 Figure 7.2. ADC2 Track and Conversion Example Timing....................................... 93 Figure 7.3. ADC2 Equivalent Input Circuit................................................................ 94 Figure 7.4. ADC2 Data Word Example .................................................................... 99 Figure 7.5. ADC Window Compare Examples, Single-Ended Mode...................... 101 Figure 7.6. ADC Window Compare Examples, Differential Mode .......................... 102 8. DACs, 12-Bit Voltage Mode (C8051F040/1/2/3 Only) Figure 8.1. DAC Functional Block Diagram............................................................ 105 9. Voltage Reference (C8051F040/2/4/6) Figure 9.1. Voltage Reference Functional Block Diagram ..................................... 113 10. Voltage Reference (C8051F041/3/5/7) Figure 10.1. Voltage Reference Functional Block Diagram.................................... 117 11. Comparators Figure 11.1. Comparator Functional Block Diagram .............................................. 121 Figure 11.2. Comparator Hysteresis Plot ............................................................... 122 12. CIP-51 Microcontroller Figure 12.1. CIP-51 Block Diagram........................................................................ 127 Figure 12.2. Memory Map ...................................................................................... 133 Figure 12.3. SFR Page Stack................................................................................. 136 Figure 12.4. SFR Page Stack While Using SFR Page 0x0F To Access Port 5...... 137 Figure 12.5. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs . 138 Figure 12.6. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR.... 139 Figure 12.7. SFR Page Stack Upon Return From PCA Interrupt ........................... 140 Figure 12.8. SFR Page Stack Upon Return From ADC2 Window Interrupt ........... 141 13. Reset Sources Figure 13.1. Reset Sources.................................................................................... 165 Figure 13.2. Reset Timing ...................................................................................... 166 14. Oscillators Figure 14.1. Oscillator Diagram.............................................................................. 173 Figure 14.2. 32.768 kHz External Crystal Example................................................ 177 15. Flash Memory Figure 15.1. Flash Program Memory Map and Security Bytes............................... 181 10 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16. External Data Memory Interface and On-Chip XRAM Figure 16.1. Multiplexed Configuration Example.................................................... 191 Figure 16.2. Non-multiplexed Configuration Example ............................................ 192 Figure 16.3. EMIF Operating Modes ...................................................................... 193 Figure 16.4. Non-multiplexed 16-bit MOVX Timing ................................................ 196 Figure 16.5. Non-multiplexed 8-bit MOVX without Bank Select Timing ................. 197 Figure 16.6. Non-multiplexed 8-bit MOVX with Bank Select Timing ...................... 198 Figure 16.7. Multiplexed 16-bit MOVX Timing........................................................ 199 Figure 16.8. Multiplexed 8-bit MOVX without Bank Select Timing ......................... 200 Figure 16.9. Multiplexed 8-bit MOVX with Bank Select Timing .............................. 201 17. Port Input/Output Figure 17.1. Port I/O Cell Block Diagram ............................................................... 203 Figure 17.2. Port I/O Functional Block Diagram ..................................................... 204 Figure 17.3. Priority Crossbar Decode Table ......................................................... 205 Figure 17.4. Priority Crossbar Decode Table ......................................................... 208 Figure 17.5. Priority Crossbar Decode Table ......................................................... 209 Figure 17.6. Crossbar Example:............................................................................. 211 18. Controller Area Network (CAN0) Figure 18.1. Typical CAN Bus Configuration.......................................................... 227 Figure 18.2. CAN Controller Diagram..................................................................... 228 Figure 18.3. Four Segments of a CAN Bit Time ..................................................... 229 Figure 18.4. CAN0DATH: CAN Data Access Register High Byte .......................... 234 19. System Management BUS/I2C BUS (SMBUS0) Figure 19.1. SMBus0 Block Diagram ..................................................................... 239 Figure 19.2. Typical SMBus Configuration ............................................................. 240 Figure 19.3. SMBus Transaction ............................................................................ 241 Figure 19.4. Typical Master Transmitter Sequence................................................ 242 Figure 19.5. Typical Master Receiver Sequence.................................................... 243 Figure 19.6. Typical Slave Transmitter Sequence.................................................. 243 Figure 19.7. Typical Slave Receiver Sequence...................................................... 244 20. Enhanced Serial Peripheral Interface (SPI0) Figure 20.1. SPI Block Diagram ............................................................................. 255 Figure 20.2. Multiple-Master Mode Connection Diagram ....................................... 258 Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 258 Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram ............. 258 Figure 20.5. Data/Clock Timing Diagram ............................................................... 260 21. UART0 Figure 21.1. UART0 Block Diagram ....................................................................... 265 Figure 21.2. UART0 Mode 0 Timing Diagram ........................................................ 266 Figure 21.3. UART0 Mode 0 Interconnect.............................................................. 267 Figure 21.4. UART0 Mode 1 Timing Diagram ........................................................ 267 Figure 21.5. UART0 Modes 2 and 3 Timing Diagram ............................................ 269 Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram .............................. 269 Figure 21.7. UART Multi-Processor Mode Interconnect Diagram .......................... 272 Rev. 1.6 11 C8051F040/1/2/3/4/5/6/7 22. UART1 Figure 22.1. UART1 Block Diagram ....................................................................... 277 Figure 22.2. UART1 Baud Rate Logic .................................................................... 278 Figure 22.3. UART Interconnect Diagram .............................................................. 279 Figure 22.4. 8-Bit UART Timing Diagram............................................................... 279 Figure 22.5. 9-Bit UART Timing Diagram............................................................... 280 Figure 22.6. UART Multi-Processor Mode Interconnect Diagram .......................... 281 23. Timers Figure 23.1. T0 Mode 0 Block Diagram.................................................................. 290 Figure 23.2. T0 Mode 2 Block Diagram.................................................................. 291 Figure 23.3. T0 Mode 3 Block Diagram.................................................................. 292 Figure 23.4. Tn Capture Mode Block Diagram ....................................................... 298 Figure 23.5. Tn Auto-reload Mode and Toggle Mode Block Diagram .................... 299 24. Programmable Counter Array Figure 24.1. PCA Block Diagram............................................................................ 305 Figure 24.2. PCA Counter/Timer Block Diagram.................................................... 306 Figure 24.3. PCA Interrupt Block Diagram ............................................................. 307 Figure 24.4. PCA Capture Mode Diagram.............................................................. 308 Figure 24.5. PCA Software Timer Mode Diagram .................................................. 309 Figure 24.6. PCA High-Speed Output Mode Diagram............................................ 310 Figure 24.7. PCA Frequency Output Mode ............................................................ 311 Figure 24.8. PCA 8-Bit PWM Mode Diagram ......................................................... 312 Figure 24.9. PCA 16-Bit PWM Mode...................................................................... 313 25. JTAG (IEEE 1149.1) 12 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 List of Tables 1. System Overview Table 1.1. Product Selection Guide ......................................................................... 20 2. Absolute Maximum Ratings Table 2.1. Absolute Maximum Ratings* .................................................................. 35 3. Global DC Electrical Characteristic Table 3.1. Global DC Electrical Characteristics ....................................................... 36 4. Pinout and Package Definitions Table 4.1. Pin Definitions ......................................................................................... 37 5. 12-Bit ADC (ADC0, C8051F040/1 Only) Table 5.1. AMUX Selection Chart (AMX0AD3–0 and AMX0CF3–0 bits) ................ 50 Table 5.2. 12-Bit ADC0 Electrical Characteristics ................................................... 67 Table 5.3. High-Voltage Difference Amplifier Electrical Characteristics .................. 68 6. 10-Bit ADC (ADC0, C8051F042/3/4/5/6/7 Only) Table 6.1. AMUX Selection Chart (AMX0AD3-0 and AMX0CF3-0 bits) .................. 72 Table 6.2. 10-Bit ADC0 Electrical Characteristics ................................................... 89 Table 6.3. High-Voltage Difference Amplifier Electrical Characteristics .................. 90 7. 8-Bit ADC (ADC2, C8051F040/1/2/3 Only) Table 7.1. AMUX Selection Chart (AMX2AD2-0 and AMX2CF3-0 bits) .................. 96 Table 7.2. ADC2 Electrical Characteristics ............................................................ 103 8. DACs, 12-Bit Voltage Mode (C8051F040/1/2/3 Only) Table 8.1. DAC Electrical Characteristics .............................................................. 111 9. Voltage Reference (C8051F040/2/4/6) Table 9.1. Voltage Reference Electrical Characteristics ....................................... 115 10. Voltage Reference (C8051F041/3/5/7) Table 10.1. Voltage Reference Electrical Characteristics ..................................... 119 11. Comparators Table 11.1. Comparator Electrical Characteristics ................................................ 126 12. CIP-51 Microcontroller Table 12.1. CIP-51 Instruction Set Summary ........................................................ 129 Table 12.2. Special Function Register (SFR) Memory Map .................................. 144 Table 12.3. Special Function Registers ................................................................. 146 Table 12.4. Interrupt Summary .............................................................................. 154 13. Reset Sources Table 13.1. Reset Electrical Characteristics .......................................................... 171 14. Oscillators Table 14.1. Internal Oscillator Electrical Characteristics ....................................... 175 15. Flash Memory Table 15.1. Flash Electrical Characteristics .......................................................... 180 16. External Data Memory Interface and On-Chip XRAM Table 16.1. AC Parameters for External Memory Interface ................................... 202 17. Port Input/Output Table 17.1. Port I/O DC Electrical Characteristics ................................................. 203 Rev. 1.6 13 C8051F040/1/2/3/4/5/6/7 18. Controller Area Network (CAN0) Table 18.1. Background System Information ........................................................ 229 Table 18.2. CAN Register Index and Reset Values .............................................. 233 19. System Management BUS/I2C BUS (SMBUS0) Table 19.1. SMB0STA Status Codes and States .................................................. 252 20. Enhanced Serial Peripheral Interface (SPI0) 21. UART0 Table 21.1. UART0 Modes .................................................................................... 266 Table 21.2. Oscillator Frequencies for Standard Baud Rates ............................... 273 22. UART1 Table 22.1. Timer Settings for Standard Baud Rates Using the Internal 24.5 MHz Oscillator ................................................................................................. 284 Table 22.2. Timer Settings for Standard Baud Rates Using an External 25.0 MHz Oscillator ................................................................................................. 284 Table 22.3. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator ............................................................................................. 285 Table 22.4. Timer Settings for Standard Baud Rates Using an External 18.432 MHz Oscillator ............................................................................................. 286 Table 22.5. Timer Settings for Standard Baud Rates Using an External 11.0592 MHz Oscillator ............................................................................................. 287 Table 22.6. Timer Settings for Standard Baud Rates Using an External 3.6864 MHz Oscillator ............................................................................................. 288 23. Timers 24. Programmable Counter Array Table 24.1. PCA Timebase Input Options ............................................................. 306 Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 307 25. JTAG (IEEE 1149.1) Table 25.1. Boundary Data Register Bit Definitions .............................................. 320 14 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 List of Registers SFR Definition 5.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 49 SFR Definition 5.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . 49 SFR Definition 5.3. AMX0PRT: Port 3 Pin Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 51 SFR Definition 5.4. HVA0CN: High Voltage Difference Amplifier Control . . . . . . . . . . . 53 SFR Definition 5.5. ADC0CF: ADC0 Configuration Register . . . . . . . . . . . . . . . . . . . . 58 SFR Definition 5.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 SFR Definition 5.7. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 60 SFR Definition 5.8. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 SFR Definition 5.9. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 62 SFR Definition 5.10. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . 62 SFR Definition 5.11. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . 62 SFR Definition 5.12. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 63 SFR Definition 6.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 71 SFR Definition 6.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . 71 SFR Definition 6.3. AMX0PRT: Port 3 Pin Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 73 SFR Definition 6.4. HVA0CN: High Voltage Difference Amplifier Control . . . . . . . . . . . 75 SFR Definition 6.5. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 SFR Definition 6.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 SFR Definition 6.7. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 82 SFR Definition 6.8. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 SFR Definition 6.9. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 84 SFR Definition 6.10. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . 84 SFR Definition 6.11. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . 84 SFR Definition 6.12. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 85 SFR Definition 7.1. AMX2CF: AMUX2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 95 SFR Definition 7.2. AMX2SL: AMUX2 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . 95 SFR Definition 7.3. ADC2CF: ADC2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 SFR Definition 7.4. ADC2CN: ADC2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 SFR Definition 7.5. ADC2: ADC2 Data Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data . . . . . . . . . . . . . . . . . . . . . . 100 SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data . . . . . . . . . . . . . . . . . . . . . . . . . 100 SFR Definition 8.1. DAC0H: DAC0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 SFR Definition 8.2. DAC0L: DAC0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 SFR Definition 8.3. DAC0CN: DAC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 SFR Definition 8.4. DAC1H: DAC1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 SFR Definition 8.5. DAC1L: DAC1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 SFR Definition 8.6. DAC1CN: DAC1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 SFR Definition 9.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 SFR Definition 10.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 SFR Definition 11.1. CPTnCN: Comparator 0, 1, and 2 Control . . . . . . . . . . . . . . . . . 124 SFR Definition 11.2. CPTnMD: Comparator Mode Selection . . . . . . . . . . . . . . . . . . . 125 SFR Definition 12.1. SFR Page Control Register: SFRPGCN . . . . . . . . . . . . . . . . . . 142 SFR Definition 12.2. SFR Page Register: SFRPAGE . . . . . . . . . . . . . . . . . . . . . . . . . 142 Rev. 1.6 15 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.3. SFR Next Register: SFRNEXT . . . . . . . . . . . . . . . . . . . . . . . . . 143 SFR Definition 12.4. SFR Last Register: SFRLAST . . . . . . . . . . . . . . . . . . . . . . . . . . 143 SFR Definition 12.5. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 SFR Definition 12.6. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 SFR Definition 12.7. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 SFR Definition 12.8. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 SFR Definition 12.9. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 SFR Definition 12.10. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 SFR Definition 12.11. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 SFR Definition 12.12. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 SFR Definition 12.13. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . 159 SFR Definition 12.14. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . 160 SFR Definition 12.15. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . 161 SFR Definition 12.16. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . 162 SFR Definition 12.18. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 SFR Definition 13.1. WDTCN: Watchdog Timer Control . . . . . . . . . . . . . . . . . . . . . . 169 SFR Definition 13.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 SFR Definition 14.1. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 174 SFR Definition 14.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 174 SFR Definition 14.3. CLKSEL: Oscillator Clock Selection . . . . . . . . . . . . . . . . . . . . . 175 SFR Definition 14.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 176 SFR Definition 15.1. FLACL: Flash Access Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 SFR Definition 15.2. FLSCL: Flash Memory Control . . . . . . . . . . . . . . . . . . . . . . . . . 184 SFR Definition 15.3. PSCTL: Program Store Read/Write Control . . . . . . . . . . . . . . . 185 SFR Definition 16.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 189 SFR Definition 16.2. EMI0CF: External Memory Configuration . . . . . . . . . . . . . . . . . 190 SFR Definition 16.3. EMI0TC: External Memory Timing Control . . . . . . . . . . . . . . . . 195 SFR Definition 17.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 212 SFR Definition 17.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 213 SFR Definition 17.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 214 SFR Definition 17.4. XBR3: Port I/O Crossbar Register 3 . . . . . . . . . . . . . . . . . . . . . 215 SFR Definition 17.5. P0: Port0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 SFR Definition 17.6. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 216 SFR Definition 17.7. P1: Port1 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 SFR Definition 17.8. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 SFR Definition 17.9. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 217 SFR Definition 17.10. P2: Port2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 SFR Definition 17.11. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 SFR Definition 17.12. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 219 SFR Definition 17.13. P3: Port3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 SFR Definition 17.14. P3MDIN: Port3 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 SFR Definition 17.15. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 220 SFR Definition 17.16. P4: Port4 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 SFR Definition 17.17. P4MDOUT: Port4 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 222 SFR Definition 17.18. P5: Port5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 16 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.19. P5MDOUT: Port5 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 223 SFR Definition 17.20. P6: Port6 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 SFR Definition 17.21. P6MDOUT: Port6 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 224 SFR Definition 17.22. P7: Port7 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 SFR Definition 17.23. P7MDOUT: Port7 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 225 SFR Definition 18.1. CAN0DATL: CAN Data Access Register Low Byte . . . . . . . . . . 235 SFR Definition 18.2. CAN0ADR: CAN Address Index . . . . . . . . . . . . . . . . . . . . . . . . 235 SFR Definition 18.3. CAN0CN: CAN Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 SFR Definition 18.4. CAN0TST: CAN Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 SFR Definition 18.5. CAN0STA: CAN Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 SFR Definition 19.1. SMB0CN: SMBus0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . 248 SFR Definition 19.3. SMB0DAT: SMBus0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 SFR Definition 19.4. SMB0ADR: SMBus0 Address . . . . . . . . . . . . . . . . . . . . . . . . . . 250 SFR Definition 19.5. SMB0STA: SMBus0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 SFR Definition 20.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 261 SFR Definition 20.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 SFR Definition 20.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 SFR Definition 21.1. SCON0: UART0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 SFR Definition 21.2. SSTA0: UART0 Status and Clock Selection . . . . . . . . . . . . . . . 275 SFR Definition 21.3. SBUF0: UART0 Data Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 SFR Definition 21.4. SADDR0: UART0 Slave Address . . . . . . . . . . . . . . . . . . . . . . . 276 SFR Definition 21.5. SADEN0: UART0 Slave Address Enable . . . . . . . . . . . . . . . . . 276 SFR Definition 22.1. SCON1: Serial Port 1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 282 SFR Definition 22.2. SBUF1: Serial (UART1) Port Data Buffer . . . . . . . . . . . . . . . . . 283 SFR Definition 23.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 SFR Definition 23.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 SFR Definition 23.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 SFR Definition 23.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 SFR Definition 23.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 SFR Definition 23.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 SFR Definition 23.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 SFR Definition 23.8. TMRnCN: Timer n Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 SFR Definition 23.9. TMRnCF: Timer n Configuration . . . . . . . . . . . . . . . . . . . . . . . . 302 SFR Definition 23.10. RCAPnL: Timer n Capture Register Low Byte . . . . . . . . . . . . . 303 SFR Definition 23.11. RCAPnH: Timer n Capture Register High Byte . . . . . . . . . . . . 303 SFR Definition 23.12. TMRnL: Timer n Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 SFR Definition 23.13. TMRnH Timer n High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 SFR Definition 24.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 SFR Definition 24.2. PCA0MD: PCA0 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 SFR Definition 24.3. PCA0CPMn: PCA0 Capture/Compare Mode . . . . . . . . . . . . . . 316 SFR Definition 24.4. PCA0L: PCA0 Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . 317 SFR Definition 24.5. PCA0H: PCA0 Counter/Timer High Byte . . . . . . . . . . . . . . . . . . 317 SFR Definition 24.6. PCA0CPLn: PCA0 Capture Module Low Byte . . . . . . . . . . . . . . 318 Rev. 1.6 17 C8051F040/1/2/3/4/5/6/7 SFR Definition 24.7. PCA0CPHn: PCA0 Capture Module High Byte . . . . . . . . . . . . . 318 JTAG Register Definition 25.1. IR: JTAG Instruction Register . . . . . . . . . . . . . . . . . . 319 JTAG Register Definition 25.2. DEVICEID: JTAG Device ID Register . . . . . . . . . . . . 322 JTAG Register Definition 25.3. FLASHCON: JTAG Flash Control Register . . . . . . . . 324 JTAG Register Definition 25.4. FLASHDAT: JTAG Flash Data . . . . . . . . . . . . . . . . . 325 JTAG Register Definition 25.5. FLASHADR: JTAG Flash Address . . . . . . . . . . . . . . 325 18 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1. System Overview The C8051F04x family of devices are fully integrated mixed-signal System-on-a-Chip MCUs with 64 digital I/O pins (C8051F040/2/4/6) or 32 digital I/O pins (C8051F041/3/5/7), and an integrated CAN 2.0B controller. Highlighted features are listed below; refer to Table 1.1 for specific product feature selection. • • • • • • • • • • • • • • High-Speed pipelined 8051-compatible CIP-51 microcontroller core (up to 25 MIPS) Controller Area Network (CAN 2.0B) Controller with 32 message objects, each with its own indentifier mask. In-system, full-speed, non-intrusive debug interface (on-chip) True 12-bit (C8051F040/1) or 10-bit (C8051F042/3/4/5/6/7) 100 ksps 8-channel ADC with PGA and analog multiplexer High Voltage Difference Amplifier input to the 12/10-bit ADC (60 V Peak-to-Peak) with programmable gain. True 8-bit 500 ksps 8-channel ADC with PGA and analog multiplexer (C8051F040/1/2/3) Two 12-bit DACs with programmable update scheduling (C8051F040/1/2/3) 64 kB (C8051F040/1/2/3/4/5) or 32 kB (C8051F046/7) of in-system programmable Flash memory 4352 (4096 + 256) bytes of on-chip RAM External Data Memory Interface with 64 kB address space SPI, SMBus/I2C, and (2) UART serial interfaces implemented in hardware Five general purpose 16-bit Timers Programmable Counter/Timer Array with six capture/compare modules On-chip Watchdog Timer, VDD Monitor, and Temperature Sensor With on-chip VDD monitor, Watchdog Timer, and clock oscillator, the C8051F04x family of devices are truly stand-alone System-on-a-Chip solutions. All analog and digital peripherals are enabled/disabled and configured by user firmware. The Flash memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. On-board JTAG debug circuitry allows non-intrusive (uses no on-chip resources), full speed, in-circuit programming and debugging using the production MCU installed in the final application. This debug system supports inspection and modification of memory and registers, setting breakpoints, watchpoints, single stepping, Run, and Halt commands. All analog and digital peripherals are fully functional while debugging using JTAG. Each MCU is specified for 2.7 V to 3.6 V operation over the industrial temperature range (–45 to +85 °C). The Port I/Os, /RST, and JTAG pins are tolerant for input signals up to 5 V. The C8051F040/2/4/6 are available in a 100-pin TQFP and the C8051F041/3/5/7 are available in a 64-pin TQFP. Rev. 1.6 19 C8051F040/1/2/3/4/5/6/7 DAC Outputs Analog Comparators Lead-free (RoHS Compliant) DAC Resolution (bits) Temperature Sensor High Voltage Diff Amp 8-bit 500 ksps ADC Inputs C8051F041 25 64 kB 4352    2 5  32  - 8    12 2 3 C8051F041-GQ 25 64 kB 4352    2 5  32  - 8    12 2 3  64TQFP C8051F042 25 64 kB 4352    2 5  64 -  8    12 2 3 Package 8    12 2 3  100TQFP Voltage Reference 10-bit 100ksps ADC - Digital Port I/O’s C8051F040-GQ 25 64 kB 4352    2 5  64  SMBus/I2C and SPI CAN 8    12 2 3 RAM - Flash Memory 25 64 kB 4352    2 5  64  C8051F040 MIPS (Peak) 12-bit 100ksps ADC UARTS Timers (16-bit) Programmable Counter Array External Memory Interface Ordering Part Number Table 1.1. Product Selection Guide - 100TQFP - 64TQFP - 100TQFP C8051F042-GQ 25 64 kB 4352    2 5  64 -  8    12 2 3  100TQFP C8051F043  8    12 2 3 25 64 kB 4352    2 5  32 - - 64TQFP C8051F043-GQ 25 64 kB 4352    2 5  32 -  8    12 2 3  64TQFP C8051F044 25 64 kB 4352    2 5  64 -     3 C8051F044-GQ 25 64 kB 4352    2 5  64 -     3  100TQFP C8051F045 25 64 kB 4352    2 5  32 -     3 C8051F045-GQ 25 64 kB 4352    2 5  32 -     3  64TQFP C8051F046 25 32 kB 4352    2 5  64 -     3 C8051F046-GQ 25 32 kB 4352    2 5  64 -     3  100TQFP C8051F047 25 32 kB 4352    2 5  32 -     3 C8051F047-GQ 25 32 kB 4352    2 5  32 -     3  64TQFP 20 Rev. 1.6 - 100TQFP - 64TQFP - 100TQFP - 64TQFP C8051F040/1/2/3/4/5/6/7 Figure 1.1. C8051F040/2 Block Diagram Rev. 1.6 21 C8051F040/1/2/3/4/5/6/7 Figure 1.2. C8051F041/3 Block Diagram 22 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 1.3. C8051F044/6 Block Diagram Rev. 1.6 23 C8051F040/1/2/3/4/5/6/7 Figure 1.4. C8051F045/7 Block Diagram 24 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1.1. CIP-51™ Microcontroller Core 1.1.1. Fully 8051 Compatible The C8051F04x family of devices utilizes Silicon Labs' proprietary CIP-51 microcontroller core. The CIP51 is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The core has all the peripherals included with a standard 8052, including five 16-bit counter/timers, two full-duplex UARTs, 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space, and up to 8 byte-wide I/O Ports. 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 with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than four system clock cycles. 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 2/3 3 3/4 4 4/5 5 8 Number of Instructions 26 50 5 14 7 3 1 2 1 With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. Figure 1.5 shows a comparison of peak throughputs of various 8-bit microcontroller cores with their maximum system clocks. Figure 1.5. Comparison of Peak MCU Execution Speeds Rev. 1.6 25 C8051F040/1/2/3/4/5/6/7 1.1.3. Additional Features The C8051F04x MCU family includes several key enhancements to the CIP-51 core and peripherals to improve overall performance and ease of use in end applications. The extended interrupt handler provides 20 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), allowing the numerous analog and digital peripherals to interrupt the controller. An interrupt driven system requires less intervention by the MCU, giving it more effective throughput. The extra interrupt sources are very useful when building multi-tasking, real-time systems. There are up to seven reset sources for the MCU: an on-board VDD monitor, a Watchdog Timer, a missing clock detector, a voltage level detection from Comparator0, a forced software reset, the CNVSTR0 input pin, and the /RST pin. The /RST pin is bi-directional, accommodating an external reset, or allowing the internally generated POR to be output on the /RST pin. Each reset source except for the VDD monitor and Reset Input pin may be disabled by the user in software; the VDD monitor is enabled/disabled via the MONEN pin. The Watchdog Timer may be permanently enabled in software after a power-on reset during MCU initialization. The MCU has an internal, stand alone clock generator which is used by default as the system clock after any reset. If desired, the clock source may be switched on the fly to the external oscillator, which can use a crystal, ceramic resonator, capacitor, RC, or external clock source to generate the system clock. This can be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switching to the fast (up to 25 MHz) internal oscillator as needed. Figure 1.6. On-Board Clock and Reset 26 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1.2. On-Chip Memory The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general purpose RAM, and direct addressing accesses the 128 byte SFR address space. The CIP-51 SFR address space contains up to 256 SFR Pages. In this way, the CIP-51 MCU can accommodate the many SFRs required to control and configure the various peripherals featured on the device. The lower 128 bytes of RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of general purpose registers, and the next 16 bytes can be byte addressable or bit addressable. The CIP-51 in the C8051F04x MCUs additionally has an on-chip 4 kB RAM block and an external memory interface (EMIF) for accessing off-chip data memory or memory-mapped peripherals. The on-chip 4 byte block can be addressed over the entire 64 kB external data memory address range (overlapping 4 kB boundaries). External data memory address space can be mapped to on-chip memory only, off-chip memory only, or a combination of the two (addresses up to 4 kB directed to on-chip, above 4 kB directed to EMIF). The EMIF is also configurable for multiplexed or non-multiplexed address/data lines. The MCU's program memory consists of 64 kB (C8051F040/1/2/3/4/5) or 32 kB (C8051F046/7) of Flash. This memory may be reprogrammed in-system in 512 byte sectors, and requires no special off-chip programming voltage. The 512 bytes from addresses 0xFE00 to 0xFFFF are reserved for the 64 kB devices. There is also a single 128 byte sector at address 0x10000 to 0x1007F, which may be useful as a small table for software constants. See Figure 1.7 for the MCU system memory map. Figure 1.7. On-Chip Memory Map Rev. 1.6 27 C8051F040/1/2/3/4/5/6/7 1.3. JTAG Debug and Boundary Scan The C8051F04x family has on-chip JTAG boundary scan and debug circuitry that provides non-intrusive, full speed, in-circuit debugging using the production part installed in the end application, via the four-pin JTAG interface. The JTAG port is fully compliant to IEEE 1149.1, providing full boundary scan for test and manufacturing purposes. Silicon Labs' debugging system supports inspection and modification of memory and registers, breakpoints, watchpoints, a stack monitor, 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 with instruction execution. The C8051F040DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F04x MCUs. The development kit includes two target boards and a cable to facilitate evaluating a simple CAN communication network. The kit also includes software with a developer's studio and debugger, a target application board with the associated MCU installed, and the required cables and wall-mount power supply. The Serial Adapter takes its power from the application board; it requires roughly 20 mA at 2.7-3.6 V. For applications where there is not sufficient power available from the target system, the provided power supply can be connected directly to the Serial Adapter. Silicon Labs’ debug environment is a vastly superior configuration for developing and debugging embedded applications compared to standard MCU emulators, which use on-board "ICE Chips" and target cables and require the MCU in the application board to be socketed. Silicon Labs' debug environment both increases ease of use and preserves the performance of the precision, on-chip analog peripherals. Figure 1.8. Development/In-System Debug Diagram 28 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1.4. Programmable Digital I/O and Crossbar The standard 8051 Ports (0, 1, 2, and 3) are available on the MCUs. The C8051F040/2/4/6 have 4 additional 8-bit ports (4, 5, 6, and 7) for a total of 64 general-purpose I/O Ports. The Ports behave like the standard 8051 with a few enhancements. Each port pin can be configured as either a push-pull or open-drain output. Also, the "weak pullups" which are normally fixed on an 8051 can be globally disabled, providing additional power saving capabilities for low-power applications. Perhaps the most unique enhancement is the Digital Crossbar. This is essentially a large digital switching network that allows mapping of internal digital system resources to Port I/O pins on P0, P1, P2, and P3 (See Figure 1.9). Unlike microcontrollers with standard multiplexed digital I/O ports, all combinations of functions are supported with all package options offered. The on-chip counter/timers, serial buses, HW interrupts, ADC Start of Conversion input, comparator outputs, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in the Crossbar Control registers. This allows the user to select the exact mix of general purpose Port I/O and digital resources needed for the particular application. Figure 1.9. Digital Crossbar Diagram Rev. 1.6 29 C8051F040/1/2/3/4/5/6/7 1.5. Programmable Counter Array The C8051F04x MCU family includes an on-board Programmable Counter/Timer Array (PCA) in addition to the five 16-bit general purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with six programmable capture/compare modules. The timebase is clocked from one of six sources: the system clock divided by 12, the system clock divided by 4, Timer 0 overflow, an External Clock Input (ECI pin), the system clock, or the external oscillator source divided by 8. Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width Modulator. The PCA Capture/Compare Module I/O and External Clock Input are routed to the MCU Port I/ O via the Digital Crossbar. Figure 1.10. PCA Block Diagram 30 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1.6. Controller Area Network The C8051F04x family of devices feature a Controller Area Network (CAN) controller that implements serial communication using the CAN protocol. The CAN controller facilitates communication on a CAN network in accordance with the Bosch specification 2.0A (basic CAN) and 2.0B (full CAN). The CAN controller consists of a CAN Core, Message RAM (separate from the C8051 RAM), a message handler state machine, and control registers. The CAN controller can operate at bit rates up to 1 Mbit/second. Silicon Labs CAN has 32 message objects each having its own identifier mask used for acceptance filtering of received messages. Incoming data, message objects and identifier masks are stored in the CAN message RAM. All protocol functions for transmission of data and acceptance filtering is performed by the CAN controller and not by the C8051 MCU. In this way, minimal CPU bandwidth is used for CAN communication. The C8051 configures the CAN controller, accesses received data, and passes data for transmission via Special Function Registers (SFR) in the C8051. Figure 1.11. CAN Controller Diagram 1.7. Serial Ports The C8051F04x MCU Family includes two Enhanced Full-Duplex UARTs, an enhanced SPI Bus, and SMBus/I2C. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little intervention by the CPU. The serial buses do not "share" resources such as timers, interrupts, or Port I/O, so any or all of the serial buses may be used together with any other. Rev. 1.6 31 C8051F040/1/2/3/4/5/6/7 1.8. 12/10-Bit Analog to Digital Converter The C8051F040/1 devices have an on-chip 12-bit SAR ADC (ADC0) with a 9-channel input multiplexer and programmable gain amplifier. With a maximum throughput of 100 ksps, the ADC offers true 12-bit performance with an INL of ±1LSB. C8051F042/3/4/5/6/7 devices include a 10-bit SAR ADC with similar specifications and configuration options. The ADC0 voltage reference is selected between the DAC0 output and an external VREF pin. On C8051F040/2/4/6 devices, ADC0 has its own dedicated VREF0 input pin; on C8051F041/3/5/7 devices, the ADC0 uses the VREFA input pin and, on the C8051F041/3, shares it with the 8-bit ADC2. The on-chip 15 ppm/°C voltage reference may generate the voltage reference for the on-chip ADCs or other system components via the VREF output pin. The ADC is under full control of the CIP-51 microcontroller via its associated Special Function Registers. One input channel is tied to an internal temperature sensor, while the other eight channels are available externally. Each pair of the eight external input channels can be configured as either two single-ended inputs or a single differential input. The system controller can also put the ADC into shutdown mode to save power. A programmable gain amplifier follows the analog multiplexer. The gain can be set to 0.5, 1, 2, 4, 8, or 16 and is software programmable. The gain stage can be especially useful when different ADC input channels have widely varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large dc offset (in differential mode, a DAC could be used to provide the dc offset). Conversions can be started in four ways; a software command, an overflow of Timer 2, an overflow of Timer 3, or an external signal input. This flexibility allows the start of conversion to be triggered by software events, external HW signals, or a periodic timer overflow signal. Conversion completions are indicated by a status bit and an interrupt (if enabled). The resulting 10- or 12-bit data word is latched into two SFRs upon completion of a conversion. The data can be right or left justified in these registers under software control. Window Compare registers for the ADC data can be configured to interrupt the controller when ADC data is 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 the specified window. Figure 1.12. 10/12-Bit ADC Block Diagram 32 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 1.9. 8-Bit Analog to Digital Converter (C8051F040/1/2/3 Only) The C8051F040/1/2/3 devices have an on-board 8-bit SAR ADC (ADC2) with an 8-channel input multiplexer and programmable gain amplifier. This ADC features a 500 ksps maximum throughput and true 8bit performance with an INL of ±1LSB. Eight input pins are available for measurement and can be programmed as single-ended or differential inputs. The ADC is under full control of the CIP-51 microcontroller via the Special Function Registers. The ADC2 voltage reference is selected between the analog power supply (AV+) and an external VREF pin. On C8051F040/2 devices, ADC2 has its own dedicated VREF2 input pin; on C8051F041/3 devices, ADC2 shares the VREFA input pin with the 12/10-bit ADC0. User software may put ADC2 into shutdown mode to save power. A programmable gain amplifier follows the analog multiplexer. The gain stage can be especially useful when different ADC input channels have widely varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large dc offset (in differential mode, a DAC could be used to provide the dc offset). The PGA gain can be set in software to 0.5, 1, 2, or 4. A flexible conversion scheduling system allows ADC2 conversions to be initiated by software commands, timer overflows, or an external input signal. ADC2 conversions may also be synchronized with ADC0 software-commanded conversions. Conversion completions are indicated by a status bit and an interrupt (if enabled), and the resulting 8-bit data word is latched into an SFR upon completion. Figure 1.13. 8-Bit ADC Diagram Rev. 1.6 33 C8051F040/1/2/3/4/5/6/7 1.10. Comparators and DACs Each C8051F040/1/2/3 MCU has two 12-bit DACs, and all C8051F04x devices have three comparators on chip. The MCU data and control interface to each comparator and DAC is via the Special Function Registers. The MCU can place any DAC or comparator in low power shutdown mode. The comparators have software programmable hysteresis and response time. Each comparator can generate an interrupt on its rising edge, falling edge, or both; these interrupts are capable of waking up the MCU from sleep mode. The comparators' output state can also be polled in software. The comparator outputs can be programmed to appear on the Port I/O pins via the Crossbar. The DACs are voltage output mode and include a flexible output scheduling mechanism. This scheduling mechanism allows DAC output updates to be forced by a software write or a Timer 2, 3, or 4 overflow. The DAC voltage reference is supplied via the dedicated VREFD input pin on C8051F040/2 devices or via the internal voltage reference on C8051F041/3 devices. The DACs are especially useful as references for the comparators or offsets for the differential inputs of the ADC. Figure 1.14. Comparator and DAC Diagram 34 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 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 any Pin (except VDD, Port I/O, and JTAG pins) with respect to DGND –0.3 — VDD + 0.3 V Voltage on any Port I/O Pin, /RST, and JTAG pins with respect to DGND –0.3 — 5.8 V Voltage on VDD with respect to DGND –0.3 — 4.2 V Maximum Total current through VDD, AV+, DGND, and AGND — — 800 mA Maximum output current sunk by any Port pin — — 100 mA Maximum output current sunk by any other I/O pin — — 50 mA Maximum output current sourced by any Port pin — — 100 mA Maximum output current sourced by any other I/O pin — — 50 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. Due to special I/O design requirements of the High Voltage Difference Amplifier, undue electrical over-voltage stress (i.e., ESD) experienced by these pads may result in impedance degradation of these inputs (HVAIN+ and HVAIN–). For this reason, care should be taken to ensure proper handling and use as typically required to prevent ESD damage to electrostatically sensitive CMOS devices (e.g., static-free workstations, use of grounding straps, over-voltage protection in end-applications, etc.) Rev. 1.6 35 C8051F040/1/2/3/4/5/6/7 3. Global DC Electrical Characteristic Table 3.1. Global DC Electrical Characteristics –40 to +85 °C, 25 MHz System Clock unless otherwise specified. Parameter Conditions Min Typ Max Units 2.7 3.0 3.6 V Internal REF, ADC, DAC, Comparators all active — 1.7 — mA Analog Supply Current with Internal REF, ADC, DAC, Comanalog sub-systems inactive parators all disabled, oscillator disabled — 0.2 — μA Analog-to-Digital Supply Delta (|VDD - AV+|) — — 0.5 V Digital Supply Voltage 2.7 3.0 3.6 V VDD = 2.7 V, Clock = 25 MHz VDD = 2.7 V, Clock = 1 MHz VDD = 2.7 V, Clock = 32 kHz — — — 10 0.5 20 — — — mA mA μA Digital Supply Current with VDD = 2.7 V, Clock = 25 MHz CPU inactive (not accessing VDD = 2.7 V, Clock = 1 MHz Flash) (Idle Mode) VDD = 2.7 V, Clock = 32 kHz — — — 5 0.2 10 — — — mA mA μA Digital Supply Current (shutdown) (Stop Mode) — 0.2 — μA — 1.5 — V –40 — +85 °C SYSCLK (system clock frequency)2 0 — 25 MHz Tsysl (SYSCLK low time) 18 — — ns Tsysh (SYSCLK high time) 18 — — ns Analog Supply Voltage1 Analog Supply Current Digital Supply Current with CPU active (Normal Mode) Oscillator not running Digital Supply RAM Data Retention Voltage Specified Operating Temperature Range Notes: 1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate. 2. SYSCLK must be at least 32 kHz to enable debugging. 36 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 4. Pinout and Package Definitions Table 4.1. Pin Definitions Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description VDD 37, 64, 90 24, 41, 57 Digital Supply Voltage. Must be tied to +2.7 to +3.6 V. DGND 38, 63, 89 25, 40, 56 Digital Ground. Must be tied to Ground. AV+ 8, 11, 14 3, 6 Analog Supply Voltage. Must be tied to +2.7 to +3.6 V. AGND 9, 10, 13 4, 5 Analog Ground. Must be tied to Ground. TMS 1 58 D In JTAG Test Mode Select with internal pullup. TCK 2 59 D In JTAG Test Clock with internal pullup. TDI 3 60 D In JTAG Test Data Input with internal pullup. TDI is latched on the rising edge of TCK. TDO 4 61 D Out JTAG Test Data Output with internal pullup. Data is shifted out on TDO on the falling edge of TCK. TDO output is a tri-state driver. /RST 5 62 D I/O Device Reset. Open-drain output of internal VDD monitor. Is driven low when VDD is < 2.7 V and MONEN is high. An external source can initiate a system reset by driving this pin low. XTAL1 26 17 A In XTAL2 27 18 MONEN 28 19 D In VDD Monitor Enable. When tied high, this pin enables the internal VDD monitor, which forces a system reset when VDD is < 2.7 V. When tied low, the internal VDD monitor is disabled. In most applications, MONEN should be connected directly to VDD. VREF 12 7 A I/O Bandgap Voltage Reference Output (all devices). DAC Voltage Reference Input (C8051F041/3 only). 8 A In ADC0 (C8051F041/3/5/7) and ADC2 (C8051F041/3 only) Voltage Reference Input. VREFA Crystal Input. This pin is the return for the internal oscillator circuit for a crystal or ceramic resonator. For a precision internal clock, connect a crystal or ceramic resonator from XTAL1 to XTAL2. If overdriven by an external CMOS clock, this becomes the system clock. A Out Crystal Output. This pin is the excitation driver for a crystal or ceramic resonator. VREF0 16 A In ADC0 Voltage Reference Input. VREF2 17 A In ADC2 Voltage Reference Input (C8051F040/2 only). VREF 15 A In DAC Voltage Reference Input (C8051F040/2 only). AIN0.0 18 A In ADC0 Input Channel 0 (See ADC0 Specification for complete description). 9 Rev. 1.6 37 C8051F040/1/2/3/4/5/6/7 Table 4.1. Pin Definitions (Continued) Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description AIN0.1 19 10 A In ADC0 Input Channel 1 (See ADC0 Specification for complete description). AIN0.2 20 11 A In ADC0 Input Channel 2 (See ADC0 Specification for complete description). AIN0.3 21 12 A In ADC0 Input Channel 3 (See ADC0 Specification for complete description). HVCAP 22 13 A I/O High Voltage Difference Amplifier Capacitor. HVREF 23 14 A In High Voltage Difference Amplifier Bias Reference. HVAIN+ 24 15 A In High Voltage Difference Amplifier Positive Signal Input. HVAIN- 25 16 A In High Voltage Difference Amplifier Negative Signal Input. CANTX 7 2 CANRX 6 1 DAC0 100 64 A Out Digital to Analog Converter 0 Voltage Output. (See DAC Specification for complete description). (C8051F040/1/2/3 only) DAC1 99 63 A Out Digital to Analog Converter 1 Voltage Output. (See DAC Specification for complete description). (C8051F040/1/2/3 only) P0.0 62 55 D I/O Port 0.0. See Port Input/Output section for complete description. P0.1 61 54 D I/O Port 0.1. See Port Input/Output section for complete description. P0.2 60 53 D I/O Port 0.2. See Port Input/Output section for complete description. P0.3 59 52 D I/O Port 0.3. See Port Input/Output section for complete description. P0.4 58 51 D I/O Port 0.4. See Port Input/Output section for complete description. P0.5/ALE 57 50 D I/O ALE Strobe for External Memory Address bus (multiplexed mode) Port 0.5 See Port Input/Output section for complete description. P0.6/RD 56 49 D I/O /RD Strobe for External Memory Address bus Port 0.6 See Port Input/Output section for complete description. P0.7/WR 55 48 D I/O /WR Strobe for External Memory Address bus Port 0.7 See Port Input/Output section for complete description. 38 D Out Controller Area Network Transmit Output. D In Controller Area Network Receive Input. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 4.1. Pin Definitions (Continued) Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description P1.0/AIN2.0/A8 36 29 A In ADC1 Input Channel 0 (See ADC1 Specification for comD I/O plete description). Bit 8 External Memory Address bus (Non-multiplexed mode) Port 1.0 See Port Input/Output section for complete description. P1.1/AIN2.1/A9 35 28 A In Port 1.1. See Port Input/Output section for complete D I/O description. P1.2/AIN2.2/ A10 34 27 A In Port 1.2. See Port Input/Output section for complete D I/O description. P1.3/AIN2.3/ A11 33 26 A In Port 1.3. See Port Input/Output section for complete D I/O description. P1.4/AIN2.4/ A12 32 23 A In Port 1.4. See Port Input/Output section for complete D I/O description. P1.5/AIN2.5/ A13 31 22 A In Port 1.5. See Port Input/Output section for complete D I/O description. P1.6/AIN2.6/ A14 30 21 A In Port 1.6. See Port Input/Output section for complete D I/O description. P1.7/AIN2.7/ A15 29 20 A In Port 1.7. See Port Input/Output section for complete D I/O description. P2.0/A8m/A0 46 37 D I/O Bit 8 External Memory Address bus (Multiplexed mode) Bit 0 External Memory Address bus (Non-multiplexed mode) Port 2.0 See Port Input/Output section for complete description. P2.1/A9m/A1 45 36 D I/O Port 2.1. See Port Input/Output section for complete description. P2.2/A10m/A2 44 35 D I/O Port 2.2. See Port Input/Output section for complete description. P2.3/A11m/A3 43 34 D I/O Port 2.3. See Port Input/Output section for complete description. P2.4/A12m/A4 42 33 D I/O Port 2.4. See Port Input/Output section for complete description. P2.5/A13m/A5 41 32 D I/O Port 2.5. See Port Input/Output section for complete description. P2.6/A14m/A6 40 31 D I/O Port 2.6. See Port Input/Output section for complete description. P2.7/A15m/A7 39 30 D I/O Port 2.7. See Port Input/Output section for complete description. Rev. 1.6 39 C8051F040/1/2/3/4/5/6/7 Table 4.1. Pin Definitions (Continued) Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description P3.0/AD0/D0 54 47 A In Bit 0 External Memory Address/Data bus (Multiplexed D I/O mode) Bit 0 External Memory Data bus (Non-multiplexed mode) Port 3.0 See Port Input/Output section for complete description. ADC0 Input. (See ADC0 Specification for complete description.) P3.1/AD1/D1 53 46 A In Port 3.1. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.2/AD2/D2 52 45 A In Port 3.2. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.3/AD3/D3 51 44 A In Port 3.3. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.4/AD4/D4 50 43 A In Port 3.4. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.5/AD5/D5 49 42 A In Port 3.5. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.6/AD6/D6 48 39 A In Port 3.6. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P3.7/AD7/D7 47 38 A In Port 3.7. See Port Input/Output section for complete D I/O description. ADC0 Input. (See ADC0 Specification for complete description.) P4.0 98 D I/O Port 4.0. See Port Input/Output section for complete description. P4.1 97 D I/O Port 4.1. See Port Input/Output section for complete description. P4.2 96 D I/O Port 4.2. See Port Input/Output section for complete description. P4.3 95 D I/O Port 4.3. See Port Input/Output section for complete description. 40 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 4.1. Pin Definitions (Continued) Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description P4.4 94 D I/O Port 4.4. See Port Input/Output section for complete description. P4.5/ALE 93 D I/O ALE Strobe for External Memory Address bus (multiplexed mode) Port 4.5 See Port Input/Output section for complete description. P4.6/RD 92 D I/O /RD Strobe for External Memory Address bus Port 4.6 See Port Input/Output section for complete description. P4.7/WR 91 D I/O /WR Strobe for External Memory Address bus Port 4.7 See Port Input/Output section for complete description. P5.0/A8 88 D I/O Bit 8 External Memory Address bus (Non-multiplexed mode) Port 5.0 See Port Input/Output section for complete description. P5.1/A9 87 D I/O Port 5.1. See Port Input/Output section for complete description. P5.2/A10 86 D I/O Port 5.2. See Port Input/Output section for complete description. P5.3/A11 85 D I/O Port 5.3. See Port Input/Output section for complete description. P5.4/A12 84 D I/O Port 5.4. See Port Input/Output section for complete description. P5.5/A13 83 D I/O Port 5.5. See Port Input/Output section for complete description. P5.6/A14 82 D I/O Port 5.6. See Port Input/Output section for complete description. P5.7/A15 81 D I/O Port 5.7. See Port Input/Output section for complete description. P6.0/A8m/A0 80 D I/O Bit 8 External Memory Address bus (Multiplexed mode) Bit 0 External Memory Address bus (Non-multiplexed mode) Port 6.0 See Port Input/Output section for complete description. P6.1/A9m/A1 79 D I/O Port 6.1. See Port Input/Output section for complete description. P6.2/A10m/A2 78 D I/O Port 6.2. See Port Input/Output section for complete description. P6.3/A11m/A3 77 D I/O Port 6.3. See Port Input/Output section for complete description. Rev. 1.6 41 C8051F040/1/2/3/4/5/6/7 Table 4.1. Pin Definitions (Continued) Name Pin Numbers F040/2/4/6 F041/3/5/7 Type Description P6.4/A12m/A4 76 D I/O Port 6.4. See Port Input/Output section for complete description. P6.5/A13m/A5 75 D I/O Port 6.5. See Port Input/Output section for complete description. P6.6/A14m/A6 74 D I/O Port 6.6. See Port Input/Output section for complete description. P6.7/A15m/A7 73 D I/O Port 6.7. See Port Input/Output section for complete description. P7.0/AD0/D0 72 D I/O Bit 0 External Memory Address/Data bus (Multiplexed mode) Bit 0 External Memory Data bus (Non-multiplexed mode) Port 7.0 See Port Input/Output section for complete description. P7.1/AD1/D1 71 D I/O Port 7.1. See Port Input/Output section for complete description. P7.2/AD2/D2 70 D I/O Port 7.2. See Port Input/Output section for complete description. P7.3/AD3/D3 69 D I/O Port 7.3. See Port Input/Output section for complete description. P7.4/AD4/D4 68 D I/O Port 7.4. See Port Input/Output section for complete description. P7.5/AD5/D5 67 D I/O Port 7.5. See Port Input/Output section for complete description. P7.6/AD6/D6 66 D I/O Port 7.6. See Port Input/Output section for complete description. P7.7/AD7/D7 65 D I/O Port 7.7. See Port Input/Output section for complete description. 42 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 4.1. TQFP-100 Pinout Diagram Rev. 1.6 43 C8051F040/1/2/3/4/5/6/7 Figure 4.2. TQFP-100 Package Drawing 44 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 4.3. TQFP-64 Pinout Diagram Rev. 1.6 45 C8051F040/1/2/3/4/5/6/7 Figure 4.4. TQFP-64 Package Drawing 46 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 5. 12-Bit ADC (ADC0, C8051F040/1 Only) The ADC0 subsystem for the C8051F040/1 consists of a 9-channel, configurable analog multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 12-bit successive-approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in Figure 5.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all configurable under software control via the Special Function Registers shown in Figure 5.1. The voltage reference used by ADC0 is selected as described in Section “9. Voltage Reference (C8051F040/2/4/6)” on page 113 for C8051F040 devices, or Section “10. Voltage Reference (C8051F041/3/5/7)” on page 117 for C8051F041 devices. The ADC0 subsystem (ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0. Figure 5.1. 12-Bit ADC0 Functional Block Diagram 5.1. Analog Multiplexer and PGA The analog multiplexer can input analog signals to the ADC from four external analog input pins (AIN0.0 AIN0.3), Port 3 port pins (optionally configured as analog input pins), High Voltage Difference Amplifier, or an internally connected on-chip temperature sensor (temperature transfer function is shown in Figure 5.6). AMUX input pairs can be programmed to operate in either differential or single-ended mode. This allows the user to select the best measurement technique for each input channel, and even accommodates mode changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are three registers associated with the AMUX: the Channel Selection register AMX0SL (SFR Definition 5.2), the Configuration register AMX0CF (SFR Definition 5.1), and the Port Pin Selection register AMX0PRT (SFR Definition 5.3). Table 5.1 shows AMUX functionality by channel for each possible configuration. The PGA amplifies the AMUX output signal by an amount determined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition 5.5). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset. Rev. 1.6 47 C8051F040/1/2/3/4/5/6/7 5.1.1. Analog Input Configuration The analog multiplexer routes signals from external analog input pins, Port 3 I/O pins (See Section “17.1.5. Configuring Port 1, 2, and 3 Pins as Analog Inputs” on page 207), a High Voltage Difference Amplifier, and an on-chip temperature sensor as shown in Figure 5.2. Figure 5.2. Analog Input Diagram Analog signals may be input from four external analog input pins (AIN0.0 through AIN0.3) as differential or single-ended measurements. Additionally, Port 3 I/O Port Pins may be configured to input analog signals. Port 3 pins configured as analog inputs are selected using the Port Pin Selection register (AMX0PRT). Any number of Port 3 pins may be selected simultaneously as inputs to the AMUX. Even numbered Port 3 pins and odd numbered Port 3 pins are routed to separate AMUX inputs. (Note: Even port pins and odd port pins that are simultaneously selected will be shorted together as “wired-OR”.) In this way, differential measurements may be made when using the Port 3 pins (voltage difference between selected even and odd Port 3 pins) as shown in Figure 5.2. The High Voltage Difference Amplifier (HVDA) will accept analog input signals and reject up to 60 volts common-mode for differential measurement of up to the reference voltage to the ADC (0 to VREF volts). The output of the HVDA can be selected as an input to the ADC using the AMUX as any other channel is selected for input. (See Section “5.2. High-Voltage Difference Amplifier” on page 52). 48 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.1. AMX0CF: AMUX0 Configuration R R R R - - - - Bit7 Bit6 Bit5 Bit4 Bits7-4: Bit3: Bit2: Bit1: Bit0: NOTE: R/W R/W PORT3IC HVDA2C Bit3 Bit2 R/W AIN23IC Bit1 R/W Reset Value AIN01IC 00000000 SFR Address: SFR Address: 0xBA SFR Page: 0 Bit0 UNUSED. Read = 0000b; Write = don’t care PORT3IC: Port 3 even/odd Pin Input Pair Configuration Bit 0: Port 3 even and odd input channels are independent single-ended inputs 1: Port 3 even and odd input channels are (respectively) +, - difference input pair HVDA2C: HVDA 2’s Compliment Bit 0: HVDA output measured as an independent single-ended input 1: HVDA result for 2’s compliment value AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit 0: AIN0.2 and AIN0.3 are independent single-ended inputs 1: AIN0.2, AIN0.3 are (respectively) +, - difference input pair AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit 0: AIN0.0 and AIN0.1 are independent single-ended inputs 1: AIN0.0, AIN0.1 are (respectively) +, - difference input pair The ADC0 Data Word is in 2’s complement format for channels configured as difference. SFR Definition 5.2. AMX0SL: AMUX0 Channel Select R R R R - - - - Bit7 Bit6 Bit5 Bit4 Bits7-4: Bits3-0: R/W R/W R/W R/W Reset Value AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBB SFR Page: 0 UNUSED. Read = 0000b; Write = don’t care AMX0AD3-0: AMX0 Address Bits 0000-1111b: ADC Inputs selected per Table 5.1. Rev. 1.6 49 C8051F040/1/2/3/4/5/6/7 AMX0CF Bits 3-0 Table 5.1. AMUX Selection Chart (AMX0AD3–0 and AMX0CF3–0 bits) AMX0AD3-0 0100 0101 0000 0001 0010 0011 0000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 HVDA 0001 +(AIN0.0) -(AIN0.1) AIN0.2 AIN0.3 0010 AIN0.0 0011 +(AIN0.0) -(AIN0.1) 0100 AIN0.0 0101 +(AIN0.0) -(AIN0.1) 0110 AIN0.0 0111 +(AIN0.0) -(AIN0.1) 1000 AIN0.0 1001 +(AIN0.0) -(AIN0.1) 1010 AIN0.0 1011 +(AIN0.0) -(AIN0.1) 1100 AIN0.0 1101 +(AIN0.0) -(AIN0.1) 1110 AIN0.0 1111 +(AIN0.0) -(AIN0.1) AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 0110 0111 1xxx AGND P3EVEN P3ODD TEMP SENSOR HVDA AGND P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 HVDA AGND +P3EVEN -P3ODD TEMP SENSOR AIN0.2 AIN0.3 HVDA AGND +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND +P3EVEN -P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) +P3EVEN -P3ODD) TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR Note: “P3EVEN” denotes even numbered and “P3ODD” odd numbered Port 3 pins selected in the AMX0PRT register. 50 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.3. AMX0PRT: Port 3 Pin Selection R/W R/W R/W R/W R/W R/W R/W R/W Reset Value PAIN7EN PAIN6EN PAIN5EN PAIN4EN PAIN3EN PAIN2EN PAIN1EN PAIN0EN 00000000 Bit7 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBD SFR Page: 0 PAIN7EN: Pin 7 Analog Input Enable Bit 0: P3.7 is not selected as an analog input to the AMUX. 1: P3.7 is selected as an analog input to the AMUX. PAIN6EN: Pin 6 Analog Input Enable Bit 0: P3.6 is not selected as an analog input to the AMUX. 1: P3.6 is selected as an analog input to the AMUX. PAIN5EN: Pin 5 Analog Input Enable Bit 0: P3.5 is not selected as an analog input to the AMUX. 1: P3.5 is selected as an analog input to the AMUX. PAIN4EN: Pin 4 Analog Input Enable Bit 0: P3.4 is not selected as an analog input to the AMUX. 1: P3.4 is selected as an analog input to the AMUX. PAIN3EN: Pin 3 Analog Input Enable Bit 0: P3.3 is not selected as an analog input to the AMUX. 1: P3.3 is enabled as an analog input to the AMUX. PAIN2EN: Pin 2 Analog Input Enable Bit 0: P3.2 is not selected as an analog input to the AMUX. 1: P3.2 is enabled as an analog input to the AMUX. PAIN1EN: Pin 1 Analog Input Enable Bit 0: P3.1 is not selected as an analog input to the AMUX. 1: P3.1 is enabled as an analog input to the AMUX. PAIN0EN: Pin 0 Analog Input Enable Bit 0: P3.0 is not selected as an analog input to the AMUX. 1: P3.0 is enabled as an analog input to the AMUX. Note:Any number of Port 3 pins may be selected simultaneously inputs to the AMUX. Odd numbered and even numbered pins that are selected simultaneously are shorted together as “wired-OR”. Rev. 1.6 51 C8051F040/1/2/3/4/5/6/7 5.2. High-Voltage Difference Amplifier The High Voltage Difference Amplifier (HVDA) can be used to measure high differential voltages up to 60 V peak-to-peak, reject high common-mode voltages up to ±60 V, and condition the signal voltage range to be suitable for input to ADC0. The input signal to the HVDA may be below AGND to –60 volts, and as high as +60 volts, making the device suitable for both single and dual supply applications. The HVDA provides a common-mode signal for the ADC via the High Voltage Reference Input (HVREF), allowing measurement of signals outside the specified ADC input range using on-chip circuitry. The HVDA has a gain of 0.05 V/V to 14 V/V. The first stage 20:1 difference amplifier has a gain of 0.05 V/V when the output amplifier is used as a unity gain buffer. When the output amplifier is set to a gain of 280 (selected using the HVGAIN bits in the High Voltage Control Register), an overall gain of 14 can be attained. The HVDA uses four available external pins: +HVAIN, –HVAIN, HVCAP, and HVREF. HVAIN+ and HVAINserve as the differential inputs to the HVDA. HVREF should be used to provide a common mode reference for input to ADC0, and to prevent the output of the HVDA circuit from saturating. The output from the HVDA circuit as calculated by Equation 5.1 must remain within the “Output Voltage Range” specification listed in Table 5.3. The ideal value for HVREF in most applications is equal to 1/2 the supply voltage for the device. When the ADC is configured for differential measurement, the HVREF signal is applied to the AINinput of the ADC, thereby removing HVREF from the measurement. HVCAP facilitates the use of a capacitor for noise filtering in conjunction with R7 (see Figure 5.3 for R7 and other approximate resistor values). Alternatively, the HVCAP could also be used to access amplification of the first stage of the HVDA at an external pin. (See Table 5.3 on page 68 for electrical specifications of the HVDA.) V OUT =   HVAIN +  –  HVAIN -    Gain + HVREF Note: The output voltage of the HVDA is selected as an input to the AIN+ input of ADC0 via its analog multiplexer (AMUX0). HVDA output voltages outside the ADC’s input range will result in saturation of the ADC input. Allow for adequate settle/tracking time for proper voltage measurements. Equation 5.1. Calculating HVDA Output Voltage to AIN+ Figure 5.3. High Voltage Difference Amplifier Functional Diagram 52 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.4. HVA0CN: High Voltage Difference Amplifier Control R/W R R R HVDAEN - - - Bit7 Bit6 Bit5 Bit4 Bit7: Bits6-3: Bits2-0: R/W R/W R/W R/W Reset Value HVGAIN3 HVGAIN2 HVGAIN1 HVGAIN0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD6 SFR Page: 0 HVDAEN: High Voltage Difference Amplifier (HVDA) Enable Bit. 0: The HVDA is disabled. 1: The HVDA is enabled. Reserved. HVGAIN3-HVGAIN0: HVDA Gain Control Bits. HVDA Gain Control Bits set the amplification gain if the difference signal input to the HVDA as defined in the table below: HVGAIN3:HVGAIN0 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 HVDA Gain 0.05 0.1 0.125 0.2 0.25 0.4 0.5 0.8 1.0 1.6 2.0 3.2 4.0 6.2 7.6 14 Rev. 1.6 53 C8051F040/1/2/3/4/5/6/7 5.3. ADC Modes of Operation ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the system clock divided by the value held in the ADC0SC bits of register ADC0CF. 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, AD0CM0) in ADC0CN. Conversions may be initiated by the following: • • • • Writing a ‘1’ to the AD0BUSY bit of ADC0CN; A Timer 3 overflow (i.e., timed continuous conversions); A rising edge detected on the external ADC convert start signal, CNVSTR0; A Timer 2 overflow (i.e., timed continuous conversions). The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag (ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L. Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in Figure 5.7) depending on the programmed state of the AD0LJST bit in the ADC0CN register. When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine when a conversion has completed (ADC0 interrupts may also be used). The recommended polling procedure is shown below. Step 1. Step 2. Step 3. Step 4. Write a ‘0’ to AD0INT; Write a ‘1’ to AD0BUSY; Poll AD0INT for ‘1’; Process ADC0 data. 5.3.2. Tracking Modes According to Table 5.2, each ADC0 conversion must be preceded by a minimum tracking time for the converted result to be accurate. The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0 operates in low-power tracking mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks after the start-of-conversion signal. When the CNVSTR0 signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on the rising edge of CNVSTR0 (see Figure 5.4). Tracking can also be disabled when the entire chip is in low power standby or sleep modes. Low-power tracking mode is also useful when AMUX or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section “5.3.3. Settling Time Requirements” on page 56). 54 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 5.4. 12-Bit ADC Track and Conversion Example Timing Rev. 1.6 55 C8051F040/1/2/3/4/5/6/7 5.3.3. Settling Time Requirements A minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 5.5 shows the equivalent ADC0 input circuits for both differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by Equation 5.2. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. Note that in Low-Power tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the tracking requirements. See Table 5.2 for absolute minimum settling/tracking time requirements. n 2 t = ln  -------  R TOTAL C SAMPLE  SA Equation 5.2. 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 ADC0 MUX resistance and any external source resistance. n is the ADC resolution in bits (12). Figure 5.5. ADC0 Equivalent Input Circuits 56 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 5.6. Temperature Sensor Transfer Function Rev. 1.6 57 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.5. ADC0CF: ADC0 Configuration Register R/W R/W R/W R/W AD0SC4 AD0SC3 AD0SC2 AD0SC1 Bit7 Bit6 Bit5 Bit4 Bits7-3: R/W R/W Reset Value AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000 Bit3 or Bit2 Bit1 Bit0 SFR Address: 0xBC SFR Page: 0 SYSCLK CLK SAR0 = ---------------------------AD0SC + 1 *Note: AD0SC is the rounded-up result. 58 R/W AD0SC4-0: ADC0 SAR Conversion Clock Period Bits SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0 SAR clock. See Table 5.2 for SAR clock configuration requirements. SYSCLK – 1 * AD0SC  ---------------------CLK SAR0 Bits2-0: R/W AMP0GN2-0: ADC0 Internal Amplifier Gain (PGA) 000: Gain = 1 001: Gain = 2 010: Gain = 4 011: Gain = 8 10x: Gain = 16 11x: Gain = 0.5 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.6. ADC0CN: ADC0 Control R/W R/W AD0EN AD0TM Bit7 Bit6 Bit7: Bit6: Bit5: Bit4: Bit3-2: Bit1: Bit0: R/W R/W R/W R/W AD0INT AD0BUSY AD0CM1 AD0CM0 Bit5 Bit4 Bit3 Bit2 R/W AD0WINT Bit1 R/W Reset Value AD0LJST 00000000 Bit Addressable SFR Address: 0xE8 SFR Page: 0 Bit0 AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. AD0TM: ADC Track Mode Bit 0: When the ADC is enabled, tracking is continuous unless a conversion is in process 1: Tracking Defined by AD0CM1-0 bits AD0INT: ADC0 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC0 has not completed a data conversion since the last time this flag 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 AD0CM1-0: ADC0 Start of Conversion Mode Select. If AD0TM = 0: 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 CNVSTR0. 11: ADC0 conversion initiated on overflow of Timer 2. If AD0TM = 1: 00: Tracking starts with the write of ‘1’ to AD0BUSY and lasts for 3 SAR clocks, followed by conversion. 01: Tracking started by the overflow of Timer 3 and last for 3 SAR clocks, followed by conversion. 10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising CNVSTR0 edge. 11: Tracking started by the overflow of Timer 2 and last for 3 SAR clocks, followed by conversion. 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 are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified. Rev. 1.6 59 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.7. ADC0H: ADC0 Data Word MSB R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: SFR Address: 0xBF SFR Page: 0 ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7-4 are the sign extension of Bit3. Bits 3-0 are the upper 4 bits of the 12-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-0 are the most-significant bits of the 12-bit ADC0 Data Word. SFR Definition 5.8. 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 Bits7-0: 60 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: SFR Address: 0xBE SFR Page: 0 ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the 12-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-4 are the lower 4 bits of the 12-bit ADC0 Data Word. Bits3-0 will always read ‘0’. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12-bit ADC0 Data Word appears in the ADC0 Data Word Registers as follows: ADC0H[3:0]:ADC0L[7:0], if AD0LJST = 0 (ADC0H[7:4] will be sign-extension of ADC0H.3 for a differential reading, otherwise = 0000b). ADC0H[7:0]:ADC0L[7:4], if AD0LJST = 1 (ADC0L[3:0] = 0000b). Example: ADC0 Data Word Conversion Map, AIN0 Input in Single-Ended Mode (AMX0CF = 0x00, AMX0SL = 0x00) ADC0H:ADC0L ADC0H:ADC0L AIN0-AGND (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (4095/4096) 0x0FFF 0xFFF0 VREF / 2 0x0800 0x8000 VREF * (2047/4096) 0x07FF 0x7FF0 0 0x0000 0x0000 Example: ADC0 Data Word Conversion Map, AIN0-AIN1 Differential Input Pair (AMX0CF = 0x01, AMX0SL = 0x00) ADC0H:ADC0L ADC0H:ADC0L AIN0-AGND (Volts) (AD0LJST = 0) (AD0LJST = 1) VREF * (2047/2048) 0x07FF 0x7FF0 VREF / 2 0x0400 0x4000 VREF * (1/2048) 0x0001 0x0010 0 0x0000 0x0000 -VREF * (1/2048) 0xFFFF (-1d) 0xFFF0 -VREF / 2 0xFC00 (-1024d) 0xC000 -VREF 0xF800 (-2048d) 0x8000 For AD0LJST = 0: Gain Code = Vin  ----------------  2 n ; ‘n’ = 12 for Single-Ended; ‘n’=11 for Differential. VREF Figure 5.7. ADC0 Data Word Example Rev. 1.6 61 C8051F040/1/2/3/4/5/6/7 5.4. ADC0 Programmable Window Detector The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed limits, and notifies the system when an out-of-bound 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 ADC0CN) can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting on page 63. Notice that the window detector flag can be asserted when the measured data is inside or outside the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx registers. SFR Definition 5.9. ADC0GTH: ADC0 Greater-Than Data High 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 11111111 Bits7-0: Bit0 SFR Address: 0xC5 SFR Page: 0 High byte of ADC0 Greater-Than Data Word. SFR Definition 5.10. ADC0GTL: ADC0 Greater-Than Data 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 11111111 Bits7-0: Bit0 SFR Address: 0xC4 SFR Page: 0 Low byte of ADC0 Greater-Than Data Word. SFR Definition 5.11. 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 Bits7-0: 62 Bit6 Bit5 Bit4 Bit3 High byte of ADC0 Less-Than Data Word. Rev. 1.6 Bit2 Bit1 Bit0 SFR Address: 0xC7 SFR Page: 0 C8051F040/1/2/3/4/5/6/7 SFR Definition 5.12. 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 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC6 SFR Page: 0 Low byte of ADC0 Less-Than Data Word. Given: AMX0SL = 0x00, AMX0CF = 0x00 AD0LJST = ‘0’, ADC0LTH:ADC0LTL = 0x0200, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0x0200 and > 0x0100. Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = ‘0’, ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0x0200. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is > 0x0200 or < 0x0100. Figure 5.8. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data Rev. 1.6 63 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = ‘0’, ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0xFFFF. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0x0100 and > 0xFFFF. (In two’s-complement math, 0xFFFF = -1.) Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = ‘0’, ADC0LTH:ADC0LTL = 0xFFFF, ADC0GTH:ADC0GTL = 0x0100. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0xFFFF or > 0x0100. (In two’s-complement math, 0xFFFF = -1.) Figure 5.9. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential Data 64 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = ‘1’, ADC0LTH:ADC0LTL = 0x2000, ADC0GTH:ADC0GTL = 0x1000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0x2000 and > 0x1000. Given: AMX0SL = 0x00, AMX0CF = 0x00, AD0LJST = ‘1’ ADC0LTH:ADC0LTL = 0x1000, ADC0GTH:ADC0GTL = 0x2000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0x1000 or > 0x2000. Figure 5.10. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data Rev. 1.6 65 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = ‘1’, ADC0LTH:ADC0LTL = 0x1000, ADC0GTH:ADC0GTL = 0xFFF0. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0x1000 and > 0xFFF0. (Two’s-complement math.) Given: AMX0SL = 0x00, AMX0CF = 0x01, AD0LJST = ‘1’, ADC0LTH:ADC0LTL = 0xFFF0, ADC0GTH:ADC0GTL = 0x1000. An ADC0 End of Conversion will cause an ADC0 Window Compare Interrupt (AD0WINT = ‘1’) if the resulting ADC0 Data Word is < 0xFFF0 or > 0x1000. (Two’s-complement math.) Figure 5.11. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data 66 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 5.2. 12-Bit ADC0 Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units DC Accuracy Resolution 12 Integral Nonlinearity bits — — ±1 LSB Differential Nonlinearity Guaranteed Monotonic — — ±1 LSB Offset Error Note 1 — 0.5±3 — LSB Full Scale Error Differential mode; See Note 1 — 0.4±3 — LSB — ±0.25 — ppm/°C Offset Temperature Coefficient Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps) Signal-to-Noise Plus Distortion 66 — — dB — –75 — dB — 80 — dB Maximum SAR Clock Frequency — — 2.5 MHz Conversion Time in SAR Clocks 16 — — clocks Track/Hold Acquisition Time 1.5 — — μs Throughput Rate — — 100 ksps 0 — VREF V AGND — AV+ V — 10 — pF Total Harmonic Distortion Up to the 5th harmonic Spurious-Free Dynamic Range Conversion Rate Analog Inputs Input Voltage Range Single-ended operation Common-mode Voltage Range Differential operation Input Capacitance Temperature Sensor Nonlinearity Notes 1, 2 — ±1 — °C Absolute Accuracy Notes 1, 2 — ±3 — °C Gain Notes 1, 2 — 2.86 ±0.034 — mV/°C Offset Notes 1, 2 (Temp = 0 °C) — 0.776 ±0.009 — V Power Supply Current (AV+ supOperating Mode, 100 ksps plied to ADC) — 450 900 μA Power Supply Rejection — ±0.3 — mV/V Power Specifications Notes: 1. Represents one standard deviation from the mean. 2. Includes ADC offset, gain, and linearity variations. Rev. 1.6 67 C8051F040/1/2/3/4/5/6/7 Table 5.3. High-Voltage Difference Amplifier Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF = 3.0 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units — — 60 V –60 — +60 V 0.1 — 2.9 V 44 52 — dB — ±3 — mV Analog Inputs Differential range peak-to-peak Common Mode Range (HVAIN+) – (HVAIN–) = 0 V Analog Output Output Voltage Range DC Performance Common Mode Rejection Ratio Vcm= –10 V to +10 V, Rs=0 Offset Voltage Noise HVCAP floating — 500 — nV/rtHz Nonlinearity G=1 — 72 — dB Small Signal Bandwidth G = 0.05 — 3 — MHz Small Signal Bandwidth G=1 — 150 — kHz — 2 — V/μs — 10 — μs Differential (HVAIN+) input — 105 — k Differential (HVAIN-) input — 98 — k Common Mode input — 51 — k HVCAP — 5 — k — 450 1000 μA Dynamic Performance Slew Rate Settling Time 0.01%, G = 0.05, 10 V step Input/Output Impedance Power Specification Quiescent Current 68 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 6. 10-Bit ADC (ADC0, C8051F042/3/4/5/6/7 Only) The ADC0 subsystem for the C8051F042/3/4/5/6/7 consists of a 9-channel, configurable analog multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 10-bit successive-approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in Figure 6.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all configurable under software control via the Special Function Registers shown in Figure 6.1. The voltage reference used by ADC0 is selected as described in Section “9. Voltage Reference (C8051F040/2/4/6)” on page 113 for C8051F042/4/6 devices, or Section “10. Voltage Reference (C8051F041/3/5/7)” on page 117 for C8051F043/5/7 devices. The ADC0 subsystem (ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0. Figure 6.1. 10-Bit ADC0 Functional Block Diagram 6.1. Analog Multiplexer and PGA The analog multiplexer can input analog signals to the ADC from four external analog input pins, Port 3 port pins (optionally configured as analog input pins), High Voltage Difference Amplifier, and an internally connected on-chip temperature sensor (temperature transfer function is shown in Figure 6.6). AMUX input pairs can be programmed to operate in either differential or single-ended mode. This allows the user to select the best measurement technique for each input channel, and even accommodates mode changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are three registers associated with the AMUX: the Channel Selection register AMX0SL (SFR Definition 6.2), the Configuration register AMX0CF (SFR Definition 6.1), and the Port Pin Selection register AMX0PRT (SFR Definition 6.3). Table 6.1 shows AMUX functionality by channel for each possible configuration. The PGA amplifies the AMUX output signal by an amount determined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition 6.5). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset. Rev. 1.6 69 C8051F040/1/2/3/4/5/6/7 6.1.1. Analog Input Configuration The analog multiplexer routes signals from external analog input pins, Port 3 I/O pins (programmed to be analog inputs), a High Voltage Difference Amplifier, and an on-chip temperature sensor as shown in Figure 6.2. Figure 6.2. Analog Input Diagram Analog signals may be input from four external analog input pins (AIN0.0 through AIN0.3) as differential or single-ended measurements. Additionally, Port 3 I/O Port Pins may be configured to input analog signals. Port 3 pins configured as analog inputs are selected using the Port Pin Selection register (AMX0PRT). Any number of Port 3 pins may be selected simultaneously as inputs to the AMUX. Even numbered Port 3 pins and odd numbered Port 3 pins are routed to separate AMUX inputs. (Note: Even port pins and odd port pins that are simultaneously selected will be shorted together as “wired-OR”.) In this way, differential measurements may be made when using the Port 3 pins (voltage difference between selected even and odd Port 3 pins) as shown in Figure 6.2. The High-Voltage Difference Amplifier (HVDA) will accept analog input signals and reject up to 60 volts common-mode for differential measurement of up to the reference voltage to the ADC (0 to VREF volts). The output of the HVDA can be selected as an input to the ADC using the AMUX as any other channel is selected for measurement. 70 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.1. AMX0CF: AMUX0 Configuration R R R R - - - - Bit7 Bit6 Bit5 Bit4 Bits7-4: Bit3: Bit2: Bit1: Bit0: NOTE: R/W R/W PORT3IC HVDA2C Bit3 Bit2 R/W R/W Reset Value AIN23IC AIN01IC 00000000 Bit1 Bit0 SFR Address: SFR Address: 0xBA SFR Page: 0 UNUSED. Read = 0000b; Write = don’t care PORT3IC: Port 3 even/odd Pin Input Pair Configuration Bit 0: Port 3 even and odd input channels are independent single-ended inputs 1: Port 3 even and odd input channels are (respectively) +, - differential input pair HVDA2C: HVDA 2’s Compliment Bit 0: HVDA output measured as an independent single-ended input 1: 2’s compliment value Result from HVDA AIN23IC: AIN2, AIN3 Input Pair Configuration Bit 0: AIN2 and AIN3 are independent single-ended inputs 1: AIN2, AIN3 are (respectively) +, - differential input pair AIN01IC: AIN0, AIN1 Input Pair Configuration Bit 0: AIN0 and AIN1 are independent single-ended inputs 1: AIN0, AIN1 are (respectively) +, - differential input pair The ADC0 Data Word is in 2’s complement format for channels configured as differential. SFR Definition 6.2. AMX0SL: AMUX0 Channel Select R R R R - - - - Bit7 Bit6 Bit5 Bit4 Bits7-4: Bits3-0: R/W R/W R/W R/W Reset Value AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBB SFR Page: 0 UNUSED. Read = 0000b; Write = don’t care AMX0AD3-0: AMX0 Address Bits 0000-1111b: ADC Inputs selected per Table 6.1. Rev. 1.6 71 C8051F040/1/2/3/4/5/6/7 AMX0CF Bits 3-0 Table 6.1. AMUX Selection Chart (AMX0AD3-0 and AMX0CF3-0 bits) AMX0AD3-0 0100 0101 0000 0001 0010 0011 0000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 HVDA 0001 +(AIN0.0) -(AIN0.1) AIN0.2 AIN0.3 0010 AIN0.0 0011 +(AIN0.0) -(AIN0.1) 0100 AIN0.0 0101 +(AIN0.0) -(AIN0.1) 0110 AIN0.0 0111 +(AIN0.0) -(AIN0.1) 1000 AIN0.0 1001 +(AIN0.0) -(AIN0.1) 1010 AIN0.0 1011 +(AIN0.0) -(AIN0.1) 1100 AIN0.0 1101 +(AIN0.0) -(AIN0.1) 1110 AIN0.0 1111 +(AIN0.0) -(AIN0.1) AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 AIN0.1 0110 0111 1xxx AGND P3EVEN P3ODD TEMP SENSOR HVDA AGND P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) P3EVEN P3ODD TEMP SENSOR AIN0.2 AIN0.3 HVDA AGND +P3EVEN -P3ODD TEMP SENSOR AIN0.2 AIN0.3 HVDA AGND +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) HVDA AGND +P3EVEN -P3ODD TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) +P3EVEN -P3ODD) TEMP SENSOR AIN0.2 AIN0.3 +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR +(AIN0.2) -(AIN0.3) +(HVDA) -(HVREF) +P3EVEN -P3ODD TEMP SENSOR Note: “P3EVEN” denotes even numbered and “P3ODD” odd numbered Port 3 pins selected in the AMX0PRT register. 72 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.3. AMX0PRT: Port 3 Pin Selection R/W R/W R/W R/W R/W R/W R/W R/W Reset Value PAIN7EN PAIN6EN PAIN5EN PAIN4EN PAIN3EN PAIN2EN PAIN1EN PAIN0EN 00000000 Bit7 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBA SFR Page: 0 PAIN7EN: Pin 7 Analog Input Enable Bit 0: P3.7 is not selected as an analog input to the AMUX. 1: P3.7 is selected as an analog input to the AMUX. PAIN6EN: Pin 6 Analog Input Enable Bit 0: P3.6 is not selected as an analog input to the AMUX. 1: P3.6 is selected as an analog input to the AMUX. PAIN5EN: Pin 5 Analog Input Enable Bit 0: P3.5 is not selected as an analog input to the AMUX. 1: P3.5 is selected as an analog input to the AMUX. PAIN4EN: Pin 4 Analog Input Enable Bit 0: P3.4 is not selected as an analog input to the AMUX. 1: P3.4 is selected as an analog input to the AMUX. PAIN3EN: Pin 3 Analog Input Enable Bit 0: P3.3 is not selected as an analog input to the AMUX. 1: P3.3 is enabled as an analog input to the AMUX. PAIN2EN: Pin 2 Analog Input Enable Bit 0: P3.2 is not selected as an analog input to the AMUX. 1: P3.2 is enabled as an analog input to the AMUX. PAIN1EN: Pin 1 Analog Input Enable Bit 0: P3.1 is not selected as an analog input to the AMUX. 1: P3.1 is enabled as an analog input to the AMUX. PAIN0EN: Pin 0 Analog Input Enable Bit 0: P3.0 is not selected as an analog input to the AMUX. 1: P3.0 is enabled as an analog input to the AMUX. NOTE: Any number of Port 3 pins may be selected simultaneously inputs to the AMUX. Odd numbered and even numbered pins that are selected simultaneously are shorted together as “wired-OR”. Rev. 1.6 73 C8051F040/1/2/3/4/5/6/7 6.2. High-Voltage Difference Amplifier The High-Voltage Difference Amplifier (HVDA) can be used to measure high differential voltages up to 60 V peak-to-peak, reject high common-mode voltages up to ±60 V, and condition the signal voltage range to be suitable for input to ADC0. The input signal to the HVDA may be below AGND to –60 volts, and as high as +60 volts, making the device suitable for both single and dual supply applications. The HVDA provides a common-mode signal for the ADC via the High Voltage Reference Input (HVREF), allowing measurement of signals outside the specified ADC input range using on-chip circuitry. The HVDA has a gain of 0.05 V/V to 14 V/V. The first stage 20:1 difference amplifier has a gain of 0.05 V/V when the output amplifier is used as a unity gain buffer. When the output amplifier is set to a gain of 280 (selected using the HVGAIN bits in the High Voltage Control Register), an overall gain of 14 can be attained. The HVDA uses four available external pins: +HVAIN, –HVAIN, HVCAP, and HVREF. HVAIN+ and HVAINserve as the differential inputs to the HVDA. HVREF should be used to provide a common mode reference for input to ADC0, and to prevent the output of the HVDA circuit from saturating. The output from the HVDA circuit as calculated by Equation 6.1 must remain within the “Output Voltage Range” specification listed in Table 6.3. The ideal value for HVREF in most applications is equal to 1/2 the supply voltage for the device. When the ADC is configured for differential measurement, the HVREF signal is applied to the AINinput of the ADC, thereby removing HVREF from the measurement. HVCAP facilitates the use of a capacitor for noise filtering in conjunction with R7 (see Figure 6.3 for R7 and other approximate resistor values). Alternatively, the HVCAP could also be used to access amplification of the first stage of the HVDA at an external pin. (See Table 6.3 on page 90 for electrical specifications of the HVDA.) V OUT =   HVAIN +  –  HVAIN -    Gain + HVREF Note: The output voltage of the HVDA is selected as an input to the AIN+ input of ADC0 via its analog multiplexer (AMUX0). HVDA output voltages outside the ADC’s input range will result in saturation of the ADC input. Allow for adequate settle/tracking time for proper voltage measurements. Equation 6.1. Calculating HVDA Output Voltage to AIN+ Figure 6.3. High Voltage Difference Amplifier Functional Diagram 74 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.4. HVA0CN: High Voltage Difference Amplifier Control R/W R R R HVDAEN - - - Bit7 Bit6 Bit5 Bit4 Bit7: Bits6-3: Bits2-0: R/W R/W R/W R/W Reset Value HVGAIN3 HVGAIN2 HVGAIN1 HVGAIN0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD6 SFR Page: 0 HVDAEN: High Voltage Difference Amplifier (HVDA) Enable Bit. 0: The HVDA is disabled. 1: The HVDA is enabled. Reserved. HVGAIN3-HVGAIN0: HVDA Gain Control Bits. HVDA Gain Control Bits set the amplification gain if the difference signal input to the HVDA as defined in the table below: HVGAIN3:HVGAIN0 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 HVDA Gain 0.05 0.1 0.125 0.2 0.25 0.4 0.5 0.8 1.0 1.6 2.0 3.2 4.0 6.2 7.6 14 Rev. 1.6 75 C8051F040/1/2/3/4/5/6/7 6.3. ADC Modes of Operation ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the system clock divided by the value held in the ADC0SC bits of register ADC0CF. 6.3.1. 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, AD0CM0) in ADC0CN. Conversions may be initiated by the following: • • • • Writing a ‘1’ to the AD0BUSY bit of ADC0CN; A Timer 3 overflow (i.e., timed continuous conversions); A rising edge detected on the external ADC convert start signal, CNVSTR0; A Timer 2 overflow (i.e., timed continuous conversions). The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag (ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L. Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in Figure 6.7) depending on the programmed state of the AD0LJST bit in the ADC0CN register. When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine when a conversion has completed (ADC0 interrupts may also be used). The recommended polling procedure is shown below. Step 1. Step 2. Step 3. Step 4. Write a ‘0’ to AD0INT; Write a ‘1’ to AD0BUSY; Poll AD0INT for ‘1’; Process ADC0 data. 6.3.2. Tracking Modes According to Table 6.2, each ADC0 conversion must be preceded by a minimum tracking time for the converted result to be accurate. The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0 operates in low-power tracking mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks after the start-of-conversion signal. When the CNVSTR0 signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on the rising edge of CNVSTR0 (see Figure 6.4). Tracking can also be disabled when the entire chip is in low power standby or sleep modes. Low-power tracking mode is also useful when AMUX or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section “6.3.3. Settling Time Requirements” on page 78). 76 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 6.4. 10-Bit ADC Track and Conversion Example Timing Rev. 1.6 77 C8051F040/1/2/3/4/5/6/7 6.3.3. Settling Time Requirements A minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 6.5 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by Equation 6.2. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. Note that in lowpower tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the tracking requirements. See Table 6.2 for absolute minimum settling/tracking time requirements. n 2 t = ln  -------  R TOTAL C SAMPLE  SA Equation 6.2. 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 ADC0 MUX resistance and any external source resistance. n is the ADC resolution in bits (10). Figure 6.5. ADC0 Equivalent Input Circuits 78 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 6.6. Temperature Sensor Transfer Function Rev. 1.6 79 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.5. ADC0CF: ADC0 Configuration R/W R/W R/W R/W AD0SC4 AD0SC3 AD0SC2 AD0SC1 Bit7 Bit6 Bit5 Bit4 Bits7-3: R/W R/W Reset Value AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000 Bit3 or Bit2 Bit1 Bit0 SFR Address: 0xBC SFR Page: 0 SYSCLK CLK SAR0 = ---------------------------AD0SC + 1 *Note: AD0SC is the rounded-up result. 80 R/W AD0SC4-0: ADC0 SAR Conversion Clock Period Bits SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0 SAR clock. See Table 6.2 on page 89 for SAR clock setting requirements. SYSCLK- – 1 * AD0SC  ---------------------CLK SAR0 Bits2-0: R/W AMP0GN2-0: ADC0 Internal Amplifier Gain (PGA) 000: Gain = 1 001: Gain = 2 010: Gain = 4 011: Gain = 8 10x: Gain = 16 11x: Gain = 0.5 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.6. ADC0CN: ADC0 Control R/W R/W AD0EN AD0TM Bit7 Bit6 Bit7: Bit6: Bit5: Bit4: Bit3-2: Bit1: Bit0: R/W R/W R/W R/W AD0INT AD0BUSY AD0CM1 AD0CM0 Bit5 Bit4 Bit3 Bit2 R/W AD0WINT Bit1 R/W Reset Value AD0LJST 00000000 Bit Addressable SFR Address: 0xE8 SFR Page: 0 Bit0 AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. AD0TM: ADC Track Mode Bit 0: When the ADC is enabled, tracking is continuous unless a conversion is in process 1: Tracking Defined by AD0CM1-0 bits AD0INT: ADC0 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC0 has not completed a data conversion since the last time this flag 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 AD0CM1-0: ADC0 Start of Conversion Mode Select. If AD0TM = 0: 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 CNVSTR0. 11: ADC0 conversion initiated on overflow of Timer 2. If AD0TM = 1: 00: Tracking starts with the write of ‘1’ to AD0BUSY and lasts for 3 SAR clocks, followed by conversion. 01: Tracking started by the overflow of Timer 3 and last for 3 SAR clocks, followed by conversion. 10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising CNVSTR0 edge. 11: Tracking started by the overflow of Timer 2 and last for 3 SAR clocks, followed by conversion. 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 are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified. Rev. 1.6 81 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.7. ADC0H: ADC0 Data Word MSB R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 SFR Address: SFR Address: 0xBF SFR Page: 0 Bit0 ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7-2 are the sign extension of Bit 1. Bits 0 and 1 are the upper 2 bits of the 10-bit ADC0 Data Word. For AD0LJST = 1: Bits 7-0 are the most-significant bits of the 10-bit ADC0 Data Word. SFR Definition 6.8. 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 Bits7-0: 82 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 SFR Address: SFR Address: 0xBE SFR Page: 0 Bit0 ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7-0 are the lower 8 bits of the 10-bit ADC0 Data Word. For AD0LJST = 1: Bits 6 and 7 are the lower 2 bits of the 10-bit ADC0 Data Word. Bits 5-0 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 10-bit ADC Data Word appears in the ADC Data Word Registers as follows: ADC0H[1:0]:ADC0L[7:0], if ADLJST = 0 (ADC0H[7:2] will be sign-extension of ADC0H.1 for a differential reading, otherwise = 000000b). ADC0H[7:0]:ADC0L[7:6], if ADLJST = 1 (ADC0L[5:0] = 000000b). Example: ADC Data Word Conversion Map, AIN0 Input in Single-Ended Mode (AMX0CF = 0x00, AMX0SL = 0x00) ADC0H:ADC0L ADC0H:ADC0L AIN0-AGND (Volts) (ADLJST = 0) (ADLJST = 1) VREF * (1023/1024) 0x03FF 0xFFC0 VREF / 2 0x0200 0x8000 VREF * (511/1024) 0x01FF 0x7FC0 0 0x0000 0x0000 Example: ADC Data Word Conversion Map, AIN0-AIN1 Differential Input Pair (AMX0CF = 0x01, AMX0SL = 0x00) ADC0H:ADC0L ADC0H:ADC0L AIN0-AGND (Volts) (ADLJST = 0) (ADLJST = 1) VREF * (511/512) 0x01FF 0x7FC0 VREF / 2 0x0100 0x4000 VREF * (1/512) 0x0001 0x0040 0 0x0000 0x0000 -VREF * (1/512) 0xFFFF (-1) 0xFFC0 -VREF / 2 0xFF00 (-256) 0xC000 -VREF 0xFE00 (-512) 0x8000 ADLJST = 0: Gain Code = Vin  ----------------  2 n ; ‘n’ = 10 for Single-Ended; ‘n’=9 for Differential. VREF Figure 6.7. ADC0 Data Word Example Rev. 1.6 83 C8051F040/1/2/3/4/5/6/7 6.4. ADC0 Programmable Window Detector The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed limits, and notifies the system when an out-of-bound 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 ADC0CN) can also be used in polled mode. The high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting on page 85. Notice that the window detector flag can be asserted when the measured data is inside or outside the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx registers. SFR Definition 6.9. ADC0GTH: ADC0 Greater-Than Data High 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 11111111 Bits7-0: Bit0 SFR Address: 0xC5 SFR Page: 0 High byte of ADC0 Greater-Than Data Word. SFR Definition 6.10. ADC0GTL: ADC0 Greater-Than Data 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 11111111 Bits7-0: Bit0 SFR Address: 0xC4 SFR Page: 0 Low byte of ADC0 Greater-Than Data Word. SFR Definition 6.11. 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 Bits7-0: 84 Bit6 Bit5 Bit4 Bit3 High byte of ADC0 Less-Than Data Word. Rev. 1.6 Bit2 Bit1 Bit0 SFR Address: 0xC7 SFR Page: 0 C8051F040/1/2/3/4/5/6/7 SFR Definition 6.12. ADC0LTL: ADC0 Less-Than Data 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 Bits7-0: Bit0 SFR Address: 0xC6 SFR Page: 0 Low byte of ADC0 Less-Than Data Word. Given: AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0, ADC0LTH:ADC0LTL = 0x0200, ADC0GTH:ADC0GTL = 0x0100. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0x0200 and > 0x0100. Given: AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 0, ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0x0200. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is > 0x0200 or < 0x0100. Figure 6.8. 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended Data Rev. 1.6 85 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x01, ADLJST = 0, ADC0LTH:ADC0LTL = 0x0100, ADC0GTH:ADC0GTL = 0xFFFF. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0x0100 and > 0xFFFF. (In two’s-complement math, 0xFFFF = -1.) Given: AMX0SL = 0x00, AMX0CF = 0x01, ADLJST = 0, ADC0LTH:ADC0LTL = 0xFFFF, ADC0GTH:ADC0GTL = 0x0100. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0xFFFF or > 0x0100. (In two’s-complement math, 0xFFFF = -1.) Figure 6.9. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential Data 86 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 1, ADC0LTH:ADC0LTL = 0x8000, ADC0GTH:ADC0GTL = 0x4000. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0x8000 and > 0x4000. Given: AMX0SL = 0x00, AMX0CF = 0x00, ADLJST = 1, ADC0LTH:ADC0LTL = 0x4000, ADC0GTH:ADC0GTL = 0x8000. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0x4000 or > 0x8000. Figure 6.10. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended Data Rev. 1.6 87 C8051F040/1/2/3/4/5/6/7 Given: AMX0SL = 0x00, AMX0CF = 0x01, ADLJST = 1, ADC0LTH:ADC0LTL = 0x4000, ADC0GTH:ADC0GTL = 0xFFC0. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0x4000 and > 0xFFC0. (Two’s-complement math.) Given: AMX0SL = 0x00, AMX0CF = 0x01, ADLJST = 1, ADC0LTH:ADC0LTL = 0xFFC0, ADC0GTH:ADC0GTL = 0x4000. An ADC End of Conversion will cause an ADC Window Compare Interrupt (ADWINT=1) if the resulting ADC Data Word is < 0xFFC0 or > 0x4000. (Two’s-complement math.) Figure 6.11. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data 88 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 6.2. 10-Bit ADC0 Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units DC Accuracy Resolution 10 Integral Nonlinearity Differential Nonlinearity Guaranteed Monotonic Offset Error Full Scale Error Differential mode Offset Temperature Coefficient bits — — ±1 LSB — — ±1 LSB — 0.2±1 — LSB — 0.1±1 — LSB — ±0.25 — ppm/°C Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps) Signal-to-Noise Plus Distortion 59 — — dB — –70 — dB — 80 — dB SAR Clock Frequency — — 2.5 MHz Conversion Time in SAR Clocks 16 — — clocks Track/Hold Acquisition Time 1.5 — — μs Throughput Rate — — 100 ksps 0 — VREF V AGND — AV+ V — 10 — pF Nonlinearity1,2 — ±1 — °C Absolute Accuracy1,2 — ±3 — °C — 2.86 ±0.034 — mV/°C — 0.776 ±0.009 — V — 450 900 μA — ±0.3 — mV/V Total Harmonic Distortion Up to the 5th harmonic Spurious-Free Dynamic Range Conversion Rate Analog Inputs Input Voltage Range Single-ended operation Common-mode Voltage Range Differential operation Input Capacitance Temperature Sensor Gain1,2 Offset1,2 Temp = 0 °C Power Specifications Power Supply Current (AV+ supplied to ADC) Operating Mode, 100 ksps Power Supply Rejection Notes: 1. Represents one standard deviation from the mean. 2. Includes ADC offset, gain, and linearity variations. Rev. 1.6 89 C8051F040/1/2/3/4/5/6/7 Table 6.3. High-Voltage Difference Amplifier Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF = 3.0 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units — — 60 V –60 — +60 V 0.1 — 2.9 V 44 52 — dB — ±3 — mV Analog Inputs Differential range peak-to-peak Common Mode Range (HVAIN+) – (HVAIN–) = 0 V Analog Output Output Voltage Range DC Performance Common Mode Rejection Ratio Vcm= –10 V to +10 V, Rs=0 Offset Voltage Noise HVCAP floating — 500 — nV/rtHz Nonlinearity G=1 — 72 — dB Small Signal Bandwidth G = 0.05 — 3 — MHz Small Signal Bandwidth G=1 — 150 — kHz — 2 — V/μs — 10 — μs Differential (HVAIN+) input — 105 — k Differential (HVAIN–) input — 98 — k Common Mode input — 51 — k HVCAP — 5 — k — 450 1000 μA Dynamic Performance Slew Rate Settling Time 0.01%, G = 0.05, 10 V step Input/Output Impedance Power Specification Quiescent Current 90 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 7. 8-Bit ADC (ADC2, C8051F040/1/2/3 Only) The ADC2 subsystem for the C8051F040/1/2/3 consists of an 8-channel, configurable analog multiplexer, a programmable gain amplifier, and a 500 ksps, 8-bit successive-approximation-register ADC with integrated track-and-hold (see block diagram in Figure 7.1). The AMUX2, PGA2, and Data Conversion Modes, are all configurable under software control via the Special Function Registers shown in Figure 7.1. The ADC2 subsystem (8-bit ADC, track-and-hold and PGA) is enabled only when the AD2EN bit in the ADC2 Control register (ADC2CN) is set to logic 1. The ADC2 subsystem is in low power shutdown when this bit is logic 0. The voltage reference used by ADC2 is selected as described in Section “9. Voltage Reference (C8051F040/2/4/6)” on page 113 for C8051F040/2 devices, or Section “10. Voltage Reference (C8051F041/3/5/7)” on page 117 for C8051F041/3 devices. Figure 7.1. ADC2 Functional Block Diagram 7.1. Analog Multiplexer and PGA Eight ADC2 channels are available for measurement, as selected by the AMX2SL register (see SFR Definition 7.2). The PGA amplifies the ADC2 output signal by an amount determined by the states of the AMP2GN2-0 bits in the ADC2 Configuration register, ADC2CF (SFR Definition 7.1). The PGA can be software-programmed for gains of 0.5, 1, 2, or 4. Gain defaults to 0.5 on reset. Important Note: AIN2 pins also function as Port 1 I/O pins, and must be configured as analog inputs when used as ADC2 inputs. To configure an AIN2 pin for analog input, set to ‘0’ the corresponding bit in register P1MDIN. Port 1 pins selected as analog inputs are skipped by the Digital I/O Crossbar. See Section “17.1.5. Configuring Port 1, 2, and 3 Pins as Analog Inputs” on page 207 for more information on configuring the AIN2 pins. Rev. 1.6 91 C8051F040/1/2/3/4/5/6/7 7.2. ADC2 Modes of Operation ADC2 has a maximum conversion speed of 500 ksps. The ADC2 conversion clock (SAR2 clock) is a divided version of the system clock, determined by the AD2SC bits in the ADC2CF register (system clock divided by (AD2SC + 1) for 0  AD2SC   31). The maximum ADC2 conversion clock is 7.5 MHz. 7.2.1. Starting a Conversion A conversion can be initiated in one of five ways, depending on the programmed states of the ADC2 Start of Conversion Mode bits (AD2CM2–0) in ADC2CN. Conversions may be initiated by the following: •Writing a ‘1’ to the AD2BUSY bit of ADC2CN; •A Timer 3 overflow (i.e., timed continuous conversions); •A rising edge detected on the external ADC convert start signal, CNVSTR2 or CNVSTR0 (see important note below); •A Timer 2 overflow (i.e., timed continuous conversions); •Writing a ‘1’ to the AD0BUSY of register ADC0CN (initiate conversion of ADC2 and ADC0 with a single software command). An important note about external convert start (CNVSTR0 and CNVSTR2): If CNVSTR2 is enabled in the digital crossbar (Section “17.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 204), CNVSTR2 will be the external convert start signal for ADC2. However, if only CNVSTR0 is enabled in the digital crossbar and CNVSTR2 is not enabled, then CNVSTR0 may serve as the start of conversion for both ADC0 and ADC2. This permits synchronous sampling of both ADC0 and ADC2. During conversion, the AD2BUSY bit is set to logic 1 and restored to 0 when conversion is complete. The falling edge of AD2BUSY triggers an interrupt (when enabled) and sets the interrupt flag in ADC2CN. Converted data is available in the ADC2 data word, ADC2. When a conversion is initiated by writing a ‘1’ to AD2BUSY, it is recommended to poll AD2INT to determine when the conversion is complete. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Write a ‘0’ to AD2INT; Write a ‘1’ to AD2BUSY; Poll AD2INT for ‘1’; Process ADC2 data. 7.2.2. Tracking Modes According to Table 7.2, each ADC2 conversion must be preceded by a minimum tracking time for the converted result to be accurate. The AD2TM bit in register ADC2CN controls the ADC2 track-and-hold mode. In its default state, the ADC2 input is continuously tracked, except when a conversion is in progress. When the AD2TM bit is logic 1, ADC2 operates in low-power tracking mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR2 (or CNVSTR0, See Section 7.2.1 above) signal is used to initiate conversions in low-power tracking mode, ADC2 tracks only when CNVSTR2 is low; conversion begins on the rising edge of CNVSTR2 (see Figure 7.2). Tracking can also be disabled (shutdown) when the entire chip is in low power standby or sleep modes. Low-power Track-and-Hold mode is also useful when AMUX or PGA settings are frequently changed, due to the settling time requirements described in Section “7.2.3. Settling Time Requirements” on page 94. 92 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 7.2. ADC2 Track and Conversion Example Timing Rev. 1.6 93 C8051F040/1/2/3/4/5/6/7 7.2.3. Settling Time Requirements A minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the ADC2 MUX resistance, the ADC2 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Figure 7.3 shows the equivalent ADC2 input circuit. The required ADC2 settling time for a given settling accuracy (SA) may be approximated by Equation 7.1. Note: An absolute minimum settling time of 0.8 μs required after any MUX selection. Note that in lowpower tracking mode, three SAR2 clocks are used for tracking at the start of every conversion. For most applications, these three SAR2 clocks will meet the tracking requirements. n 2 t = ln  -------  R TOTAL C SAMPLE  SA Equation 7.1. ADC2 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 ADC2 MUX resistance and any external source resistance. n is the ADC resolution in bits (8). Figure 7.3. ADC2 Equivalent Input Circuit 94 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 7.1. AMX2CF: AMUX2 Configuration R R R R R/W R/W R/W R/W Reset Value PIN01IC 00000000 - - - - PIN67IC PIN45IC PIN23IC Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-4: Bit3: Bit2: Bit1: Bit0: NOTE: Bit0 SFR Address: 0xBA SFR Page: 2 UNUSED. Read = 0000b; Write = don’t care PIN67IC: P1.6, P1.7 Input Pair Configuration Bit 0: P1.6 and P1.7 are independent single-ended inputs 1: P1.6, P1.7 are (respectively) +, - differential input pair PIN45IC: P1.4, P1.5 Input Pair Configuration Bit 0: P1.4 and P1.5 are independent single-ended inputs 1: P1.4, P1.5 are (respectively) +, - differential input pair PIN23IC: P1.2, P1.3 Input Pair Configuration Bit 0: P1.2 and P1.3 are independent single-ended inputs 1: P1.2, P1.3 are (respectively) +, - differential input pair PIN01IC: P1.0, P1.1 Input Pair Configuration Bit 0: P1.0 and P1.1 are independent single-ended inputs 1: P1.0, P1.1 are (respectively) +, - differential input pair The ADC2 Data Word is in 2’s complement format for channels configured as differential. SFR Definition 7.2. AMX2SL: AMUX2 Channel Select R R R R R - - - - - Bit7 Bit6 Bit5 Bit4 Bit3 Bits7-3: Bits2-0: R/W R/W R/W Reset Value AMX2AD2 AMX2AD1 AMX2AD0 00000000 Bit2 Bit1 Bit0 SFR Address: 0xBB SFR Page: 2 UNUSED. Read = 00000b; Write = don’t care AMX2AD2-0: AMX2 Address Bits 000-111b: ADC Inputs selected per Table 7.1. Rev. 1.6 95 C8051F040/1/2/3/4/5/6/7 AMX2CF Bits 3-0 Table 7.1. AMUX Selection Chart (AMX2AD2-0 and AMX2CF3-0 bits) 96 000 001 010 AMX2AD2-0 011 100 101 110 111 0000 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 0001 +(P1.0) -(P1.1) -(P1.0) +(P1.1) P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 0010 P1.0 P1.1 +(P1.2) -(P1.3) -(P1.2) +(P1.3) P1.4 P1.5 P1.6 P1.7 0011 +(P1.0) -(P1.1) -(P1.0) +(P1.1) +(P1.2) -(P1.3) -(P1.2) +(P1.3) P1.4 P1.5 P1.6 P1.7 0100 P1.0 P1.1 P1.2 P1.3 +(P1.4) -(P1.5) -(P1.4) +(P1.5) P1.6 P1.7 0101 +(P1.0) -(P1.1) -(P1.0) +(P1.1) P1.2 P1.3 +(P1.4) -(P1.5) -(P1.4) +(P1.5) P1.6 P1.7 0110 P1.0 P1.1 +(P1.2) -(P1.3) -(P1.2) +(P1.3) +(P1.4) -(P1.5) -(P1.4) +(P1.5) P1.6 P1.7 0111 +(P1.0) -(P1.1) -(P1.0) +(P1.1) +(P1.2) -(P1.3) -(P1.2) +(P1.3) +(P1.4) -(P1.5) -(P1.4) +(P1.5) P1.6 P1.7 1000 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1001 +(P1.0) -(P1.1) -(P1.0) +(P1.1) P1.2 P1.3 P1.4 P1.5 +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1010 P1.0 P1.1 +(P1.2) -(P1.3) -(P1.2) +(P1.3) P1.4 P1.5 +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1011 +(P1.0) -(P1.1) -(P1.0) +(P1.1) +(P1.2) -(P1.3) -(P1.2) +(P1.3) P1.4 P1.5 +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1100 P1.0 P1.1 P1.2 P1.3 +(P1.4) -(P1.5) -(P1.4) +(P1.5) +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1101 +(P1.0) -(P1.1) -(P1.0) +(P1.1) P1.2 P1.3 +(P1.4) -(P1.5) -(P1.4) +(P1.5) +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1110 P1.0 P1.1 +(P1.2) -(P1.3) -(P1.2) +(P1.3) +(P1.4) -(P1.5) -(P1.4) +(P1.5) +(P1.6) -(P1.7) -(P1.6) +(P1.7) 1111 +(P1.0) -(P1.1) -(P1.0) +(P1.1) +(P1.2) -(P1.3) -(P1.2) +(P1.3) +(P1.4) -(P1.5) -(P1.4) +(P1.5) +(P1.6) -(P1.7) -(P1.6) +(P1.7) Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 7.3. ADC2CF: ADC2 Configuration R/W R/W R/W R/W R/W AD2SC4 AD2SC3 AD2SC2 AD2SC1 AD2SC0 - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bits7-3: R R/W R/W Reset Value AMP2GN1 AMP2GN0 11111000 Bit1 Bit0 SFR Address: 0xBC SFR Page: 2 AD2SC4-0: ADC2 SAR Conversion Clock Period Bits SAR Conversion clock is derived from system clock by the following equation, where AD2SC refers to the 5-bit value held in AD2SC4-0. SAR conversion clock requirements are given in Table 7.2. SYSCLK – 1 * AD2SC  ---------------------CLK SAR2 or SYSCLK – CLK SAR2 = ---------------------------AD2SC + 1 *Note: AD2SC is the rounded-up result. Bit2: Bits1-0: UNUSED. Read = 0b. Write = don’t care. AMP2GN1-0: ADC2 Internal Amplifier Gain (PGA) 00: Gain = 0.5 01: Gain = 1 10: Gain = 2 11: Gain = 4 Rev. 1.6 97 C8051F040/1/2/3/4/5/6/7 SFR Definition 7.4. ADC2CN: ADC2 Control R/W R/W AD2EN AD2TM Bit7 Bit6 R/W R/W R/W R/W AD2INT AD2BUSY AD2CM2 AD2CM1 Bit5 Bit4 Bit3 Bit7: Bit2 R/W AD2CM0 Bit1 R/W Reset Value AD2WINT 00000000 Bit0 SFR Address: 0xE8 SFR Page: 2 AD2EN: ADC2 Enable Bit. 0: ADC2 Disabled. ADC2 is in low-power shutdown. 1: ADC2 Enabled. ADC2 is active and ready for data conversions. Bit6: AD2TM: ADC2 Track Mode Bit. 0: Normal Track Mode: When ADC2 is enabled, tracking is continuous unless a conversion is in process. 1: Low-power Track Mode: Tracking defined by AD2CM2-0 bits (see below). Bit5: AD2INT: ADC2 Conversion Complete Interrupt Flag. This flag must be cleared by software. 0: ADC2 has not completed a data conversion since the last time this flag was cleared. 1: ADC2 has completed a data conversion. Bit4: AD2BUSY: ADC2 Busy Bit. Read: 0: ADC2 Conversion is complete or a conversion is not currently in progress. AD2INT is set to logic 1 on the falling edge of AD2BUSY. 1: ADC2 Conversion is in progress. Write: 0: No Effect. 1: Initiates ADC2 Conversion if AD2CM2-0 = 000b Bits3-1: AD2CM2-0: ADC2 Start of Conversion Mode Select. AD2TM = 0: 000: ADC2 conversion initiated on every write of ‘1’ to AD2BUSY. 001: ADC2 conversion initiated on overflow of Timer 3. 010: ADC2 conversion initiated on rising edge of external CNVSTR2 or CNVSTR0. 011: ADC2 conversion initiated on overflow of Timer 2. 1xx: ADC2 conversion initiated on write of ‘1’ to AD0BUSY (synchronized with ADC0 softwarecommanded conversions). AD2TM = 1: 000: Tracking initiated on write of ‘1’ to AD2BUSY and lasts 3 SAR2 clocks, followed by conversion. 001: Tracking initiated on overflow of Timer 3 and lasts 3 SAR2 clocks, followed by conversion. 010: ADC2 tracks only when CNVSTR2 (or CNVSTR0, See Section 7.2.1) input is logic low; conversion starts on rising CNVSTR2 edge. 011: Tracking initiated on overflow of Timer 2 and lasts 3 SAR2 clocks, followed by conversion. 1xx: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR2 clocks, followed by conversion. Bit0: AD2WINT: ADC2 Window Compare Interrupt Flag. 0: ADC2 window comparison data match has not occurred since this flag was last cleared. 1: ADC2 window comparison data match has occurred. This flag must be cleared in software. An important note about external convert start (CNVSTR0 and CNVSTR2): If CNVSTR2 is enabled in the digital crossbar (Section “17.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 204), CNVSTR2 will be the external convert start signal for ADC2. However, if only CNVSTR0 is enabled in the digital crossbar and CNVSTR2 is not enabled, then CNVSTR0 may serve as the start of conversion for both ADC0 and ADC2. 98 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 7.5. ADC2: ADC2 Data Word R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBE SFR Page: 2 ADC2 Data Word. 8-bit ADC Data Word appears in the ADC2 Data Word Register as follows: Example: ADC2 Data Word Conversion Map, AIN1.0 Input (AMX2SL = 0x00) AIN1.0-AGND ADC2 (Volts) VREF * (255/256) 0xFF VREF / 2 0x80 VREF * (127/256) 0x7F 0 0x00 Gain Code = Vin  ----------------  256 VREF Figure 7.4. ADC2 Data Word Example Rev. 1.6 99 C8051F040/1/2/3/4/5/6/7 7.3. ADC2 Programmable Window Detector The ADC2 Programmable Window Detector continuously compares the ADC2 output to user-programmed limits, and notifies the system when an out-of-bound 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 (AD2WINT in ADC2CN) can also be used in polled mode. The reference words are loaded into the ADC2 Greater-Than and ADC2 Less-Than registers (ADC2GT and ADC2LT). Notice that the window detector flag can be asserted when the measured data is inside or outside the user-programmed limits, depending on the programming of the ADC2GT and ADC2LT registers. SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data 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 11111111 Bits7-0: Bit0 SFR Address: 0xC4 SFR Page: 2 High byte of ADC2 Greater-Than Data Word. SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC6 SFR Page: 2 Low byte of ADC2 Greater-Than Data Word. 7.3.1. Window Detector in Single-Ended Mode Figure 7.5 shows two example window comparisons for Single-ended mode, with ADC2LT = 0x20 and ADC2GT = 0x10. In Single-ended mode, the codes vary from 0 to VREF x (255/256) and are represented as 8-bit unsigned integers. In the left example, an AD2WINT interrupt will be generated if the ADC2 conversion word (ADC2) is within the range defined by ADC2GT and ADC2LT (if 0x10  ADC2  0x20). In the right example, and AD2WINT interrupt will be generated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2  0x10 or ADC2  0x20). 100 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 7.5. ADC Window Compare Examples, Single-Ended Mode Rev. 1.6 101 C8051F040/1/2/3/4/5/6/7 7.3.2. Window Detector in Differential Mode Figure 7.6 shows two example window comparisons for differential mode, with ADC2LT = 0x10 (+16d) and ADC2GT = 0xFF (–1d). Notice that in Differential mode, the codes vary from –VREF to VREF x (127/128) and are represented as 8-bit 2s complement signed integers. In the left example, an AD2WINT interrupt will be generated if the ADC2 conversion word (ADC2L) is within the range defined by ADC2GT and ADC2LT (if 0xFF (–1d) < ADC2 < 0x0F (16d)). In the right example, an AD2WINT interrupt will be generated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2 < 0xFF (–1d) or ADC2 > 0x10 (+16d)). Figure 7.6. ADC Window Compare Examples, Differential Mode 102 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 7.2. ADC2 Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF2 = 2.40 V (REFBE = 0), PGA2 = 1, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units DC Accuracy Resolution 8 Integral Nonlinearity Differential Nonlinearity Guaranteed Monotonic Offset Error Full Scale Error Differential mode bits — — ±1 LSB — — ±1 LSB — 0.5±0.3 — LSB — –1±0.2 — LSB Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 500 ksps) Signal-to-Noise Plus Distortion 45 47 — dB — –51 — dB — 52 — dB SAR Conversion Clock Frequency — — 6 MHz Conversion Time in SAR Clocks 8 — — clocks 300 — — ns — — 500 ksps 0 — VREF V Common Mode Range 0 — AV+ V Input Capacitance — 5 — pF — 420 900 μA — ±0.3 — mV/V Total Harmonic Distortion Up to the 5th harmonic Spurious-Free Dynamic Range Conversion Rate Track/Hold Acquisition Time Throughput Rate Analog Inputs Input Voltage Range Single-ended Power Specifications Power Supply Current (AV+ supplied to ADC2) Operating Mode, 500 ksps Power Supply Rejection Rev. 1.6 103 C8051F040/1/2/3/4/5/6/7 8. DACs, 12-Bit Voltage Mode (C8051F040/1/2/3 Only) Each C8051F040/1/2/3 devices include two on-chip 12-bit voltage-mode Digital-to-Analog Converters (DACs). Each DAC has an output swing of 0 V to (VREF – 1 LSB) for a corresponding input code range of 0x000 to 0xFFF. The DACs may be enabled/disabled via their corresponding control registers, DAC0CN and DAC1CN. While disabled, the DAC output is maintained in a high-impedance state, and the DAC supply current falls to 1 μA or less. The voltage reference for each DAC is supplied at the VREFD pin (C8051F040/2 devices) or the VREF pin (C8051F041/3 devices). Note that the VREF pin on C8051F041/3 devices may be driven by the internal voltage reference or an external source. If the internal voltage reference is used it must be enabled in order for the DAC outputs to be valid. See Section “9. Voltage Reference (C8051F040/2/4/6)” on page 113 or Section “10. Voltage Reference (C8051F041/3/5/7)” on page 117 for more information on configuring the voltage reference for the DACs. Figure 8.1. DAC Functional Block Diagram Rev. 1.6 105 C8051F040/1/2/3/4/5/6/7 8.1. DAC Output Scheduling Each DAC features a flexible output update mechanism which allows for seamless full-scale changes and supports jitter-free updates for waveform generation. The following examples are written in terms of DAC0, but DAC1 operation is identical. 8.1.1. Update Output On-Demand In its default mode (DAC0CN.[4:3] = ‘00’) the DAC0 output is updated “on-demand” on a write to the highbyte of the DAC0 data register (DAC0H). It is important to note that writes to DAC0L are held, and have no effect on the DAC0 output until a write to DAC0H takes place. If writing a full 12-bit word to the DAC data registers, the 12-bit data word is written to the low byte (DAC0L) and high byte (DAC0H) data registers. Data is latched into DAC0 after a write to the corresponding DAC0H register, so the write sequence should be DAC0L followed by DAC0H if the full 12-bit resolution is required. The DAC can be used in 8bit mode by initializing DAC0L to the desired value (typically 0x00), and writing data to only DAC0H (also see Section 8.2 for information on formatting the 12-bit DAC data word within the 16-bit SFR space). 8.1.2. Update Output Based on Timer Overflow Similar to the ADC operation, in which an ADC conversion can be initiated by a timer overflow independently of the processor, the DAC outputs can use a Timer overflow to schedule an output update event. This feature is useful in systems where the DAC 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 DAC output. When the DAC0MD bits (DAC0CN.[4:3]) are set to ‘01’, ‘10’, or ‘11’, writes to both DAC data registers (DAC0L and DAC0H) are held until an associated Timer overflow event (Timer 3, Timer 4, or Timer 2, respectively) occurs, at which time the DAC0H:DAC0L contents are copied to the DAC input latches allowing the DAC output to change to the new value. 8.2. DAC Output Scaling/Justification In some instances, input data should be shifted prior to a DAC0 write operation to properly justify data within the DAC input registers. This action would typically require one or more load and shift operations, adding software overhead and slowing DAC throughput. To alleviate this problem, the data-formatting feature provides a means for the user to program the orientation of the DAC0 data word within data registers DAC0H and DAC0L. The three DAC0DF bits (DAC0CN.[2:0]) allow the user to specify one of five data word orientations as shown in the DAC0CN register definition. DAC1 is functionally the same as DAC0 described above. The electrical specifications for both DAC0 and DAC1 are given in Table 8.1. 106 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 8.1. DAC0H: DAC0 High 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 Bits7-0: Bit0 SFR Address: 0xD3 SFR Page: 0 DAC0 Data Word Most Significant Byte. SFR Definition 8.2. DAC0L: DAC0 Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD2 SFR Page: 0 DAC0 Data Word Least Significant Byte. Rev. 1.6 107 C8051F040/1/2/3/4/5/6/7 SFR Definition 8.3. DAC0CN: DAC0 Control R/W R R DAC0EN - - Bit7 Bit6 Bit5 Bit7: Bits6-5: Bits4-3: Bits2-0: R/W R/W R/W R/W R/W Reset Value DAC0MD1 DAC0MD0 DAC0DF2 DAC0DF1 DAC0DF0 00000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD4 SFR Page: 0 DAC0EN: DAC0 Enable Bit. 0: DAC0 Disabled. DAC0 Output pin is disabled; DAC0 is in low-power shutdown mode. 1: DAC0 Enabled. DAC0 Output pin is active; DAC0 is operational. UNUSED. Read = 00b; Write = don’t care. DAC0MD1-0: DAC0 Mode Bits. 00: DAC output updates occur on a write to DAC0H. 01: DAC output updates occur on Timer 3 overflow. 10: DAC output updates occur on Timer 4 overflow. 11: DAC output updates occur on Timer 2 overflow. DAC0DF2-0: DAC0 Data Format Bits: 000: The most significant nibble of the DAC0 Data Word is in DAC0H[3:0], while the least significant byte is in DAC0L. DAC0H DAC0L MSB 001: LSB The most significant 5-bits of the DAC0 Data Word is in DAC0H[4:0], while the least significant 7-bits are in DAC0L[7:1]. DAC0H DAC0L MSB 010: LSB The most significant 6-bits of the DAC0 Data Word is in DAC0H[5:0], while the least significant 6-bits are in DAC0L[7:2]. DAC0H DAC0L MSB 011: LSB The most significant 7-bits of the DAC0 Data Word is in DAC0H[6:0], while the least significant 5-bits are in DAC0L[7:3]. DAC0H DAC0L MSB 1xx: LSB The most significant 8-bits of the DAC0 Data Word is in DAC0H[7:0], while the least significant 4-bits are in DAC0L[7:4]. DAC0H DAC0L MSB 108 LSB Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 8.4. DAC1H: DAC1 High 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 Bits7-0: Bit0 SFR Address: 0xD3 SFR Page: 1 DAC1 Data Word Most Significant Byte. SFR Definition 8.5. DAC1L: DAC1 Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD2 SFR Page: 1 DAC1 Data Word Least Significant Byte. Rev. 1.6 109 C8051F040/1/2/3/4/5/6/7 SFR Definition 8.6. DAC1CN: DAC1 Control R/W R/W R/W DAC1EN - - Bit7 Bit6 Bit5 R/W R/W R/W R/W R/W Reset Value DAC1MD1 DAC1MD0 DAC1DF2 DAC1DF1 DAC1DF0 00000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR 0xD4 Address: 1 SFR Page: Bit7: Bits6-5: Bits4-3: Bits2-0: DAC1EN: DAC1 Enable Bit. 0: DAC1 Disabled. DAC1 Output pin is disabled; DAC1 is in low-power shutdown mode. 1: DAC1 Enabled. DAC1 Output pin is active; DAC1 is operational. UNUSED. Read = 00b; Write = don’t care. DAC1MD1-0: DAC1 Mode Bits: 00: DAC output updates occur on a write to DAC1H. 01: DAC output updates occur on Timer 3 overflow. 10: DAC output updates occur on Timer 4 overflow. 11: DAC output updates occur on Timer 2 overflow. DAC1DF2: DAC1 Data Format Bits: 000: The most significant nibble of the DAC1 Data Word is in DAC1H[3:0], while the least significant byte is in DAC1L. DAC1H DAC1L MSB 001: LSB The most significant 5-bits of the DAC1 Data Word is in DAC1H[4:0], while the least significant 7-bits are in DAC1L[7:1]. DAC1H DAC1L MSB 010: LSB The most significant 6-bits of the DAC1 Data Word is in DAC1H[5:0], while the least significant 6-bits are in DAC1L[7:2]. DAC1H DAC1L MSB 011: LSB The most significant 7-bits of the DAC1 Data Word is in DAC1H[6:0], while the least significant 5-bits are in DAC1L[7:3]. DAC1H DAC1L MSB 1xx: LSB The most significant 8-bits of the DAC1 Data Word is in DAC1H[7:0], while the least significant 4-bits are in DAC1L[7:4]. DAC1H DAC1L MSB 110 LSB Rev. 1.6 C8051F040/1/2/3/4/5/6/7 . Table 8.1. DAC Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), No Output Load unless otherwise specified. Parameter Conditions Min Typ Max Units Static Performance Resolution 12 Integral Nonlinearity — Differential Nonlinearity — ±2 bits — LSB ±1 LSB No Output Filter 100 kHz Output Filter 10 kHz Output Filter — — — 250 128 41 — — — μVrms Output Noise Offset Error Data Word = 0x014 — ±3 ±30 mV Offset Tempco — 6 — ppm/°C Full-Scale Error — ±20 ±60 mV Full-Scale Error Tempco — 10 — ppm/°C VDD Power Supply Rejection Ratio — –60 — dB Output Impedance in Shutdown DACnEN = 0 Mode — 100 — k Output Sink Current — 300 — μA Data Word = 0xFFF — 15 — mA Voltage Output Slew Rate Load = 40 pF — 0.44 — V/μs Output Settling Time to 1/2 LSB Load = 40 pF, Output swing from code 0xFFF to 0x014 — 10 — μs 0 — VREF – LSB V — 10 — μs — 60 — ppm — 110 400 μA Output Short-Circuit Current Dynamic Performance Output Voltage Swing Startup Time Analog Outputs Load Regulation IL = 0.01 mA to 0.3 mA at code 0xFFF Power Consumption (each DAC) Power Supply Current (AV+ supplied to DAC) Data Word = 0x7FF Rev. 1.6 111 C8051F040/1/2/3/4/5/6/7 9. Voltage Reference (C8051F040/2/4/6) The voltage reference circuit offers full flexibility in operating the ADC and DAC modules. Three voltage reference input pins allow each ADC and the two DACs (C8051F040/2 only) to reference an external voltage reference or the on-chip voltage reference output. ADC0 may also reference the DAC0 output internally, and ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 9.1. The internal voltage reference circuit consists of a 1.2 V, temperature stable bandgap voltage reference generator and a gain-of-two output buffer amplifier. The internal reference may be routed via the VREF pin to external system components or to the voltage reference input pins shown in Figure 9.1. Bypass capacitors of 0.1 μF and 4.7 μF are recommended from the VREF pin to AGND, as shown in Figure 9.1. See Table 9.1 for voltage reference specifications. The Reference Control Register, REF0CN (defined in SFR Definition 9.1) enables/disables the internal reference generator and selects the reference inputs for ADC0 and ADC2. The BIASE bit in REF0CN enables the on-board reference generator while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 μA (typical) and the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the reference voltage generator, BIASE and REFBE must both be set to logic 1. If the internal reference is not used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if either DAC or ADC is used, regardless of the voltage reference used. If neither the ADC nor the DAC are being used, both of these bits can be set to logic 0 to conserve power. Bits AD0VRS and AD2VRS select the ADC0 and ADC2 voltage reference sources, respectively. The electrical specifications for the Voltage Reference are given in Table 9.1. The temperature sensor connects to the highest order input of the ADC0 input multiplexer (see Section “5.1. Analog Multiplexer and PGA” on page 47 for C8051F040 devices, or Section “6.1. Analog Multiplexer and PGA” on page 69 for C8051F042/4/6 devices). The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any A/D measurements performed on the sensor while disabled result in meaningless data. Figure 9.1. Voltage Reference Functional Block Diagram Rev. 1.6 113 C8051F040/1/2/3/4/5/6/7 SFR Definition 9.1. REF0CN: Reference Control R/W R/W - - - Bit7 Bit6 Bit5 Bits7-5: Bit4: Bit3: Bit2: Bit1: Bit0: 114 R/W R/W R/W AD0VRS AD2VRS Bit4 Bit3 R/W R/W R/W Reset Value TEMPE BIASE REFBE 00000000 Bit2 Bit1 Bit0 SFR Address: 0xD1 SFR Page: 0 UNUSED. Read = 000b; Write = don’t care. AD0VRS: ADC0 Voltage Reference Select 0: ADC0 voltage reference from VREF0 pin. 1: ADC0 voltage reference from DAC0 output (C8051F040/2 only). AD2VRS: ADC2 Voltage Reference Select (C8051F040/2 only). 0: ADC2 voltage reference from VREF2 pin. 1: ADC2 voltage reference from AV+. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor Off. 1: Internal Temperature Sensor On. BIASE: ADC/DAC Bias Generator Enable Bit. (Must be ‘1’ if using ADC or DAC). 0: Internal Bias Generator Off. 1: Internal Bias Generator On. REFBE: Internal Reference Buffer Enable Bit. 0: Internal Reference Buffer Off. 1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 9.1. Voltage Reference Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, –40 to +85°C unless otherwise specified. Parameter Conditions Min Typ Max Units 2.36 2.43 2.48 V VREF Short-Circuit Current — — 30 mA VREF Temperature Coefficient — 15 — ppm/°C Internal Reference (REFBE = 1) Output Voltage 25 °C ambient Load Regulation Load = 0 to 200 μA to AGND — 0.5 — ppm/μA VREF Turn-on Time 1 4.7 μF tantalum, 0.1 μF ceramic bypass — 2 — ms VREF Turn-on Time 2 0.1 μF ceramic bypass — 20 — μs VREF Turn-on Time 3 no bypass cap — 10 — μs Reference Buffer Power Supply Current — 40 — μA Power Supply Rejection — 140 — ppm/V 1.00 — (AV+) – 0.3 V — 0 1 μA External Reference (REFBE = 0) Input Voltage Range Input Current Rev. 1.6 115 C8051F040/1/2/3/4/5/6/7 10. Voltage Reference (C8051F041/3/5/7) The internal voltage reference circuit consists of a 1.2 V, temperature stable bandgap voltage reference generator and a gain-of-two output buffer amplifier. The internal reference may be routed via the VREF pin to external system components or to the VREFA input pin shown in Figure 10.1. Bypass capacitors of 0.1 μF and 4.7 μF are recommended from the VREF pin to AGND, as shown in Figure 10.1. See Table 10.1 for voltage reference specifications. The VREFA pin provides a voltage reference input for ADC0 and ADC2 (C8051F041/3 only). ADC0 may also reference the DAC0 output internally (C8051F041/3 only), and ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 10.1. The Reference Control Register, REF0CN (defined in SFR Definition 10.1) enables/disables the internal reference generator and selects the reference inputs for ADC0 and ADC2. The BIASE bit in REF0CN enables the on-board reference generator while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 μA (typical) and the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the reference voltage generator, BIASE and REFBE must both be set to 1 (this includes any time a DAC is used). If the internal reference is not used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if either ADC is used, regardless of the voltage reference used. If neither the ADC nor the DAC are being used, both of these bits can be set to logic 0 to conserve power. Bits AD0VRS and AD2VRS select the ADC0 and ADC2 voltage reference sources, respectively. The electrical specifications for the Voltage Reference are given in Table 10.1. The temperature sensor connects to the highest order input of the ADC0 input multiplexer (see Section “5.1. Analog Multiplexer and PGA” on page 47 for C8051F041 devices that feature a 12-bit ADC, or Section “6.1. Analog Multiplexer and PGA” on page 69 for C8051F043/5/7 devices that feature a 10-bit ADC). The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any A/D measurements performed on the sensor while disabled result in meaningless data. Figure 10.1. Voltage Reference Functional Block Diagram Rev. 1.6 117 C8051F040/1/2/3/4/5/6/7 SFR Definition 10.1. REF0CN: Reference Control R/W R/W - - - Bit7 Bit6 Bit5 Bits7-5: Bit4: Bit3: Bit2: Bit1: Bit0: 118 R/W R/W R/W AD0VRS AD1VRS Bit4 Bit3 R/W R/W R/W Reset Value TEMPE BIASE REFBE 00000000 Bit2 Bit1 Bit0 SFR Address: 0xD1 SFR Page: 0 UNUSED. Read = 000b; Write = don’t care. AD0VRS: ADC0 Voltage Reference Select 0: ADC0 voltage reference from VREFA pin. 1: ADC0 voltage reference from DAC0 output (C8051F041/3 only). AD2VRS: ADC2 Voltage Reference Select (C8051F041/3 only). 0: ADC2 voltage reference from VREFA pin. 1: ADC2 voltage reference from AV+. TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor Off. 1: Internal Temperature Sensor On. BIASE: ADC/DAC Bias Generator Enable Bit. (Must be ‘1’ if using ADC or DAC). 0: Internal Bias Generator Off. 1: Internal Bias Generator On. REFBE: Internal Reference Buffer Enable Bit. 0: Internal Reference Buffer Off. 1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 10.1. Voltage Reference Electrical Characteristics VDD = 3.0 V, AV+ = 3.0 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units 2.36 2.43 2.48 V VREF Short-Circuit Current — — 30 mA VREF Temperature Coefficient — 15 — ppm/°C Internal Reference (REFBE = 1) Output Voltage 25 °C ambient Load Regulation Load = 0 to 200 μA to AGND — 0.5 — ppm/μA VREF Turn-on Time 1 4.7 μF tantalum, 0.1 μF ceramic bypass — 2 — ms VREF Turn-on Time 2 0.1 μF ceramic bypass — 20 — μs VREF Turn-on Time 3 no bypass cap — 10 — μs Reference Buffer Power Supply Current — 40 — μA Power Supply Rejection — 140 — ppm/V 1.00 — (AV+) – 0.3 V — 0 1 μA External Reference (REFBE = 0) Input Voltage Range Input Current Rev. 1.6 119 C8051F040/1/2/3/4/5/6/7 11. Comparators C8051F04x family of devices include three on-chip programmable voltage comparators, shown in Figure 11.1. Each comparator offers programmable response time and hysteresis. When assigned to a Port pin, the Comparator output may be configured as open drain or push-pull, and Comparator inputs should be configured as analog inputs (see Section “17.1.5. Configuring Port 1, 2, and 3 Pins as Analog Inputs” on page 207). The Comparator may also be used as a reset source (see Section “13.5. Comparator0 Reset” on page 167). The output of a Comparator can be polled by software, used as an interrupt source, used as a reset source, and/or routed to a Port pin. Each comparator can be individually enabled and disabled (shutdown). 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 1 μA. See Section “17.1.1. Crossbar Pin Assignment and Allocation” on page 205 for details on configuring the Comparator output via the digital Crossbar. The Comparator inputs can be externally driven from -0.25 V to (VDD) + 0.25 V without damage or upset. The complete electrical specifications for the Comparator are given in Table 11.1. The Comparator response time may be configured in software using the CPnMD1-0 bits in register CPTnMD (see SFR Definition 11.2). Selecting a longer response time reduces the amount of power consumed by the comparator. See Table 11.1 for complete timing and current consumption specifications. Figure 11.1. Comparator Functional Block Diagram Rev. 1.6 121 C8051F040/1/2/3/4/5/6/7 Figure 11.2. Comparator Hysteresis Plot The hysteresis of the Comparator is software-programmable via its Comparator Control register (CPTnCN). 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 11.1). The amount of negative hysteresis voltage is determined by the settings of the CPnHYN bits. As shown in Table 11.1, settings of approximately 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 the setting the CPnHYP bits. Comparator interrupts can be generated on either rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “12.3. Interrupt Handler” on page 153). The rising and/ or falling -edge interrupts are enabled using the comparator’s Rising/Falling Edge Interrupt Enable Bits (CPnRIE and CPnFIE) in their respective Comparator Mode Selection Register (CPTnMD), shown in SFR Definition 11.2. These bits allow the user to control which edge (or both) will cause a comparator interrupt. However, the comparator interrupt must also be enabled in the Extended Interrupt Enable Register (EIE1). The CPnFIF flag is set to logic 1 upon a Comparator falling-edge interrupt, and the CPnRIF flag is set to logic 1 upon the Comparator rising-edge interrupt. Once set, these bits remain set until cleared by software. The output state of a Comparator can be obtained at any time by reading the CPnOUT bit. A Comparator is enabled by setting its respective CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0.Upon enabling a comparator, the output of the comparator is not immediately valid. Before using a comparator as an interrupt or reset source, software should wait for a minimum of the specified “Power-up time” as specified in Table 11.1, “Comparator Electrical Characteristics,” on page 126. 122 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 11.1. Comparator Inputs The Port pins selected as comparator inputs should be configured as analog inputs in the Port 2 Input Configuration Register (for details on Port configuration, see Section “17.1.3. Configuring Port Pins as Digital Inputs” on page 206). The inputs for Comparator are on Port 2 as follows: Comparator Input Port PIN CP0+ P2.6 CP0– P2.7 CP1+ P2.2 CP1– P2.3 CP2+ P2.4 CP2– P2.5 Rev. 1.6 123 C8051F040/1/2/3/4/5/6/7 SFR Definition 11.1. CPTnCN: Comparator 0, 1, and 2 Control R/W R R/W CPnEN CPnOUT CPnRIF R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 SFR Address: CPT0CN: 0x88; CPT1CN: 0x88; CPT2CN: 0x88 SFR Pages: CPT0CN:page 1;CPT1CN:page 2; CPT2CN:page 3 Bit7: Bit6: Bit5: Bit4: Bits3-2: Bits1-0: R/W R/W R/W Reset Value CPnFIF CPnHYP1 CPnHYP0 CPnHYN1 CPnHYN0 00000000 Bit2 Bit1 Bit0 CPnEN: Comparator Enable Bit. (Please see note below.) 0: Comparator Disabled. 1: Comparator Enabled. CPnOUT: Comparator Output State Flag. 0: Voltage on CPn+ < CPn–. 1: Voltage on CPn+ > CPn–. CPnRIF: Comparator Rising-Edge Interrupt Flag. 0: No Comparator Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator Rising Edge Interrupt has occurred. Must be cleared by software. CPnFIF: Comparator Falling-Edge Interrupt Flag. 0: No Comparator Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator Falling-Edge Interrupt has occurred. Must be cleared by software. CPnHYP1-0: Comparator Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. CPnHYN1-0: Comparator Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. NOTE: Upon enabling a comparator, the output of the comparator is not immediately valid. Before using a comparator as an interrupt or reset source, software should wait for a minimum of the specified “Power-up time” as specified in Table 11.1, “Comparator Electrical Characteristics,” on page 126. 124 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 11.2. CPTnMD: Comparator Mode Selection R/W R/W R/W R/W R R - - CPnRIE CPnFIE - - Bit7 Bit6 Bit5 Bit4 Bit3 SFR Address: CPT0MD: 0x89; CPT1MD: 0x89;CPT2MD: 0x89 SFR Page: CPT0MD:page 1;CPT1MD:page 2; CPT2MD:page 3 Bits7-6: Bit 5: Bit 4: Bits3-2: Bits1-0: Bit2 R/W R/W Reset Value CPnMD1 CPnMD0 00000010 Bit1 Bit0 UNUSED. Read = 00b, Write = don’t care. CPnRIE: Comparator Rising-Edge Interrupt Enable Bit. 0: Comparator rising-edge interrupt disabled. 1: Comparator rising-edge interrupt enabled. CPnFIE: Comparator Falling-Edge Interrupt Enable Bit. 0: Comparator falling-edge interrupt disabled. 1: Comparator falling-edge interrupt enabled. UNUSED. Read = 00b, Write = don’t care. CPnMD1-CPnMD0: Comparator Mode Select These bits select the response time for the Comparator. Mode 0 1 2 3 CPnMD1 CPnMD0 0 0 0 1 1 0 1 1 CPn Typical Response Time Fastest Response Time — — Lowest Power Consumption Rev. 1.6 125 C8051F040/1/2/3/4/5/6/7 Table 11.1. Comparator Electrical Characteristics VDD = 3.0 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units Response Time, Mode 0 CPn+ – CPn– = 100 mV — 100 — ns CPn+ – CPn– = 10 mV — 250 — ns Response Time, Mode 1 CPn+ – CPn– = 100 mV — 175 — ns CPn+ – CPn– = 10 mV — 500 — ns Response Time, Mode 2 CPn+ – CPn– = 100 mV — 320 — ns CPn+ – CPn– = 10 mV — 1100 — ns Response Time, Mode 3 CPn+ – CPn– = 100 mV — 1050 — ns CPn+ – CPn– = 10 mV — 5200 — ns — 1.5 4 mV/V Common-Mode Rejection Ratio Positive Hysteresis 1 CPnHYP1-0 = 00 — 0 1 mV Positive Hysteresis 2 CPnHYP1-0 = 01 2 4.5 7 mV Positive Hysteresis 3 CPnHYP1-0 = 10 4 9 13 mV Positive Hysteresis 4 CPnHYP1-0 = 11 10 17 25 mV Negative Hysteresis 1 CPnHYN1-0 = 00 0 1 mV Negative Hysteresis 2 CPnHYN1-0 = 01 2 4.5 7 mV Negative Hysteresis 3 CPnHYN1-0 = 10 4 9 13 mV Negative Hysteresis 4 CPnHYN1-0 = 11 10 17 25 mV VDD + 0.25 V Inverting or Non-Inverting Input Voltage Range –0.25 Input Capacitance — 7 — pF Input Bias Current –5 0.001 +5 nA Input Offset Voltage –5 +5 mV Power Supply Power Supply Rejection — 0.1 1 mV/V Power-up Time — 10 — μs Mode 0 — 7.6 — μA Mode 1 — 3.2 — μA Mode 2 — 1.3 — μA Mode 3 — 0.4 — μA Supply Current at DC 126 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12. 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 MCU family has a superset of all the peripherals included with a standard 8051. Included are five 16-bit counter/timers (see description in Section 23), two full-duplex UARTs (see description in Section 21 and Section 22), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (see Section 12.2.6), and 8/4 byte-wide I/O Ports (see description in Section 17). The CIP-51 also includes on-chip debug hardware (see description in Section 25), and interfaces directly with the MCUs' 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 12.1 for a block diagram). The CIP-51 includes the following features: - Fully Compatible with MCS-51 Instruction Set 25 MIPS Peak Throughput with 25 MHz Clock 0 to 25 MHz Clock Frequency 256 Bytes of Internal RAM 8/4 Byte-Wide I/O Ports - Extended Interrupt Handler Reset Input Power Management Modes On-chip Debug Logic Program and Data Memory Security Figure 12.1. CIP-51 Block Diagram Rev. 1.6 127 C8051F040/1/2/3/4/5/6/7 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 maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute 1 2 2/3 3 3/4 4 4/5 5 8 Number of Instructions 26 50 5 14 7 3 1 2 1 Programming and Debugging Support A JTAG-based serial interface is provided for in-system programming of the Flash program memory and communication with on-chip debug support logic. The re-programmable Flash can also be read and changed 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 and watch points, 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 debug is completely non-intrusive and non-invasive, requiring no RAM, Stack, timers, or other on-chip resources. The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs provides an integrated development environment (IDE) including editor, macro assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via its JTAG interface to provide fast and efficient in-system device programming and debugging. Third party macro assemblers and C compilers are also available. 128 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12.1. 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. 12.1.1. Instruction and CPU Timing In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based solely on clock cycle timing. All instruction timings are specified in terms of clock cycles. Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 12.1 is the CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock cycles for each instruction. 12.1.2. MOVX Instruction and Program Memory In the CIP-51, the MOVX instruction serves three purposes: accessing on-chip XRAM, accessing off-chip XRAM, and accessing on-chip program Flash memory. The Flash access feature provides a mechanism for user software to update program code and use the program memory space for non-volatile data storage (see Section “15. Flash Memory” on page 179). The External Memory Interface provides a fast access to off-chip XRAM (or memory-mapped peripherals) via the MOVX instruction. Refer to Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for details. Table 12.1. CIP-51 Instruction Set Summary Mnemonic Description 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 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 Rev. 1.6 Bytes Clock Cycles 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 1 1 2 2 2 1 2 2 2 1 2 2 2 1 1 2 2 1 129 C8051F040/1/2/3/4/5/6/7 Table 12.1. CIP-51 Instruction Set Summary (Continued) Mnemonic Description DEC Rn DEC direct DEC @Ri INC DPTR MUL AB DIV AB DA 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 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 ANL A, Rn ANL A, direct ANL A, @Ri ANL A, #data ANL direct, A ANL direct, #data ORL A, Rn ORL A, direct ORL A, @Ri ORL A, #data ORL direct, A ORL direct, #data XRL A, Rn XRL A, direct XRL A, @Ri XRL A, #data XRL direct, A XRL direct, #data CLR A CPL A RL A RLC A RR A RRC A SWAP A 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 130 1 2 1 1 1 1 1 Clock Cycles 1 2 2 1 4 8 1 1 2 1 2 2 3 1 2 1 2 2 3 1 2 1 2 2 3 1 1 1 1 1 1 1 1 2 2 2 2 3 1 2 2 2 2 3 1 2 2 2 2 3 1 1 1 1 1 1 1 1 2 1 2 1 2 2 2 2 3 2 1 2 2 2 1 2 2 2 2 3 2 Bytes Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 12.1. CIP-51 Instruction Set Summary (Continued) Mnemonic Description MOV direct, #data MOV @Ri, A MOV @Ri, direct MOV @Ri, #data MOV DPTR, #data16 MOVC A, @A+DPTR MOVC A, @A+PC MOVX A, @Ri MOVX @Ri, A MOVX A, @DPTR MOVX @DPTR, A PUSH direct POP direct XCH A, Rn XCH A, direct XCH A, @Ri XCHD A, @Ri Move immediate to direct byte Move A to indirect RAM Move direct byte to indirect RAM Move immediate to indirect RAM Load DPTR with 16-bit constant Move code byte relative DPTR to A Move code byte relative PC to A Move external data (8-bit address) to A Move A to external data (8-bit address) Move external data (16-bit address) to A Move A to external data (16-bit address) Push direct byte onto stack Pop direct byte from stack 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 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 3 1 2 2 3 1 1 1 1 1 1 2 2 1 2 1 1 Clock Cycles 3 2 2 2 3 3 3 3 3 3 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 2/3 2/3 3/4 3/4 3/4 2 3 1 1 2 3 2 1 2 3 4 5 5 3 4 3 3 2/3 Bytes Rev. 1.6 131 C8051F040/1/2/3/4/5/6/7 Table 12.1. CIP-51 Instruction Set Summary (Continued) Mnemonic Description JNZ rel CJNE A, direct, rel CJNE A, #data, rel Jump if A does not equal zero Compare direct byte to A and jump if not equal Compare immediate to A and jump if not equal Compare immediate to Register and jump if not equal Compare immediate to indirect and jump if not equal Decrement Register and jump if not zero Decrement direct byte and jump if not zero No operation CJNE Rn, #data, rel CJNE @Ri, #data, rel DJNZ Rn, rel DJNZ direct, rel NOP 2 3 3 Clock Cycles 2/3 3/4 3/4 3 3/4 3 4/5 2 3 1 2/3 3/4 1 Bytes 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 64 kB program memory space. There is one unused opcode (0xA5) that performs the same function as NOP. All mnemonics copyrighted © Intel Corporation 1980. 132 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12.2. Memory Organization The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same address space but are accessed via different instruction types. There are 256 bytes of internal data memory and 64k bytes of internal program memory address space implemented within the CIP-51. The CIP-51 memory organization is shown in Figure 12.2. Figure 12.2. Memory Map 12.2.1. Program Memory The CIP-51 has a 64 kB program memory space. The MCU implements 64 kB (C8051F040/1/2/3/4/5) and 32 kB (C8051F046/7) of this program memory space as in-system re-programmed Flash memory, organized in a contiguous block from addresses 0x0000 to 0xFFFF (C8051F040/1/2/3/4/5) and 0x0000 to 0x7FFF (C8051F046/7). Note: 512 bytes from 0xFE00 to 0xFFFF (C8051F040/1/2/3/4/5 only) of this memory are reserved for factory use and are not available for user program storage. Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for nonvolatile data storage. Refer to Section “15. Flash Memory” on page 179 for further details. Rev. 1.6 133 C8051F040/1/2/3/4/5/6/7 12.2.2. Data Memory The CIP-51 implements 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (SFR) but is physically separate from the SFR space. The addressing mode used by an instruction when accessing locations above 0x7F determines whether the CPU accesses the upper 128 bytes of data memory space or the SFR’s. 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 12.2 illustrates the data memory organization of the CIP-51. 12.2.3. 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 12.8). This allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes use registers R0 and R1 as index registers. 12.2.4. Bit Addressable Locations In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20 through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from 0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or 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. 12.2.5. 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, address 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; 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. The MCUs also have built-in hardware for a stack record which is accessed by the debug logic. The stack record is a 32-bit shift register, where each PUSH or increment SP pushes one record bit onto the register, and each CALL pushes two record bits onto the register. (A POP or decrement SP pops one record bit, 134 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 and a RET pops two record bits, also.) The stack record circuitry can also detect an overflow or underflow on the 32-bit shift register, and can notify the debug software even with the MCU running at speed. 12.2.6. Special Function Registers The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers (SFR’s). The SFR’s provide control and data exchange with the CIP-51's resources and peripherals. The CIP-51 duplicates the SFR’s found in a typical 8051 implementation as well as implementing additional SFR’s 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 12.2 lists the SFR’s implemented in the CIP-51 System Controller. The SFR registers are accessed whenever the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFR’s with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, P1, SCON, IE, etc.) are bit-addressable as well as byte-addressable. All other SFR’s 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 datasheet, as indicated in Table 12.3, for a detailed description of each register. 12.2.6.1. SFR Paging The CIP-51 features SFR paging, allowing the device to map many SFR’s into the 0x80 to 0xFF memory address space. The SFR memory space has 256 pages. In this way, each memory location from 0x80 to 0xFF can access up to 256 SFR’s. The C8051F04x family of devices utilizes five SFR pages: 0, 1, 2, 3, and F. SFR pages are selected using the Special Function Register Page Selection register, SFRPAGE (see SFR Definition 12.2). The procedure for reading and writing an SFR is as follows: 1. Select the appropriate SFR page number using the SFRPAGE register. 2. Use direct accessing mode to read or write the special function register (MOV instruction). 12.2.6.2. Interrupts and SFR Paging When an interrupt occurs, the SFR Page Register will automatically switch to the SFR page containing the flag bit that caused the interrupt. The automatic SFR Page switch function conveniently removes the burden of switching SFR pages from the interrupt service routine. Upon execution of the RETI instruction, the SFR page is automatically restored to the SFR Page in use prior to the interrupt. This is accomplished via a three-byte SFR Page Stack. The top byte of the stack is SFRPAGE, the current SFR Page. The second byte of the SFR Page Stack is SFRNEXT. The third, or bottom byte of the SFR Page Stack is SFRLAST. On interrupt, the current SFRPAGE value is pushed to the SFRNEXT byte, and the value of SFRNEXT is pushed to SFRLAST. Hardware then loads SFRPAGE with the SFR Page containing the flag bit associated with the interrupt. On a return from interrupt, the SFR Page Stack is popped resulting in the value of SFRNEXT returning to the SFRPAGE register, thereby restoring the SFR page context without software intervention. The value in SFRLAST (0x00 if there is no SFR Page value in the bottom of the stack) of the stack is placed in SFRNEXT register. If desired, the values stored in SFRNEXT and SFRLAST may be modified during an interrupt, enabling the CPU to return to a different SFR Page upon execution of the RETI instruction (on interrupt exit). Modifying registers in the SFR Page Stack does not cause a push or pop of the stack. Only interrupt calls and returns will cause push/pop operations on the SFR Page Stack. Rev. 1.6 135 C8051F040/1/2/3/4/5/6/7 Figure 12.3. SFR Page Stack Automatic hardware switching of the SFR Page on interrupts may be enabled or disabled as desired using the SFR Automatic Page Control Enable Bit located in the SFR Page Control Register (SFRPGCN). This function defaults to ‘enabled’ upon reset. In this way, the autoswitching function will be enabled unless disabled in software. A summary of the SFR locations (address and SFR page) is provided in Table 12.2. in the form of an SFR memory map. Each memory location in the map has an SFR page row, denoting the page in which that SFR resides. Note that certain SFR’s are accessible from ALL SFR pages, and are denoted by the “(ALL PAGES)” designation. For example, the Port I/O registers P0, P1, P2, and P3 all have the “(ALL PAGES)” designation, indicating these SFR’s are accessible from all SFR pages regardless of the SFRPAGE register value. 12.2.6.3. SFR Page Stack Example The following is an example of a C8051F040 device that shows the operation of the SFR Page Stack during interrupts. In this example, the SFR Page Control is left in the default enabled state (i.e., SFRPGEN = 1), and the CIP-51 is executing in-line code that is writing values to Port 5 (SFR “P5”, located at address 0xD8 on SFR Page 0x0F). The device is also using the Programmable Counter Array (PCA) and the 8-bit ADC (ADC2) window comparator to monitor a voltage. The PCA is timing a critical control function in its interrupt service routine (ISR), so its interrupt is enabled and is set to high priority. The ADC2 is monitoring a voltage that is less important, but to minimize the software overhead its window comparator is being used with an associated ISR that is set to low priority. At this point, the SFR page is set to access the Port 5 SFR (SFRPAGE = 0x0F). See Figure 12.4 below. 136 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 12.4. SFR Page Stack While Using SFR Page 0x0F To Access Port 5 While CIP-51 executes in-line code (writing values to Port 5 in this example), an ADC2 Window Comparator Interrupt occurs. The CIP-51 vectors to the ADC2 Window Comparator ISR and pushes the current SFR Page value (SFR Page 0x0F) into SFRNEXT in the SFR Page Stack. The SFR page needed to access ADC2’s SFR’s is then automatically placed in the SFRPAGE register (SFR Page 0x02). SFRPAGE is considered the “top” of the SFR Page Stack. Software can now access the ADC2 SFR’s. Software may switch to any SFR Page by writing a new value to the SFRPAGE register at any time during the ADC2 ISR to access SFR’s that are not on SFR Page 0x02. See Figure 12.5. Rev. 1.6 137 C8051F040/1/2/3/4/5/6/7 Figure 12.5. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs While in the ADC2 ISR, a PCA interrupt occurs. Recall the PCA interrupt is configured as a high priority interrupt, while the ADC2 interrupt is configured as a low priority interrupt. Thus, the CIP-51 will now vector to the high priority PCA ISR. Upon doing so, the CIP-51 will automatically place the SFR page needed to access the PCA’s special function registers into the SFRPAGE register, SFR Page 0x00. The value that was in the SFRPAGE register before the PCA interrupt (SFR Page 2 for ADC2) is pushed down the stack into SFRNEXT. Likewise, the value that was in the SFRNEXT register before the PCA interrupt (in this case SFR Page 0x0F for Port 5) is pushed down to the SFRLAST register, the “bottom” of the stack. Note that a value stored in SFRLAST (via a previous software write to the SFRLAST register) will be overwritten. See Figure 12.6 below. 138 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 12.6. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR On exit from the PCA interrupt service routine, the CIP-51 will return to the ADC2 Window Comparator ISR. On execution of the RETI instruction, SFR Page 0x00 used to access the PCA registers will be automatically popped off of the SFR Page Stack, and the contents of the SFRNEXT register will be moved to the SFRPAGE register. Software in the ADC2 ISR can continue to access SFR’s as it did prior to the PCA interrupt. Likewise, the contents of SFRLAST are moved to the SFRNEXT register. Recall this was the SFR Page value 0x0F being used to access Port 5 before the ADC2 interrupt occurred. See Figure 12.7 below. Rev. 1.6 139 C8051F040/1/2/3/4/5/6/7 Figure 12.7. SFR Page Stack Upon Return From PCA Interrupt On the execution of the RETI instruction in the ADC2 Window Comparator ISR, the value in SFRPAGE register is overwritten with the contents of SFRNEXT. The CIP-51 may now access the Port 5 SFR bits as it did prior to the interrupts occurring. See Figure 12.8 below. 140 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Figure 12.8. SFR Page Stack Upon Return From ADC2 Window Interrupt Note that in the above example, all three bytes in the SFR Page Stack are accessible via the SFRPAGE, SFRNEXT, and SFRLAST special function registers. If the stack is altered while servicing an interrupt, it is possible to return to a different SFR Page upon interrupt exit than selected prior to the interrupt call. Direct access to the SFR Page stack can be useful to enable real-time operating systems to control and manage context switching between multiple tasks. Push operations on the SFR Page Stack only occur on interrupt service, and pop operations only occur on interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFRPGCN). See SFR Definition 12.1. Rev. 1.6 141 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.1. SFR Page Control Register: SFRPGCN R R R R R R R - - - - - - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-1: Bit0: R/W Reset Value SFRPGEN 00000001 Bit0 SFR Address: 0x81 SFR Page: All Pages Reserved. SFRPGEN: SFR Automatic Page Control Enable. Upon interrupt the C8051 Core will vector to the specified interrupt service routine and automatically switch the SFR page to the corresponding peripheral or function’s SFR page. This bit is used to control this autopaging function. 0: SFR Automatic Paging disabled. C8051 core will not automatically change to the appropriate SFR page (i.e., the SFR page that contains the SFR’s for the peripheral/function that was the source of the interrupt). 1: SFR Automatic Paging enabled. Upon interrupt, the CIP-51 will switch the SFR page to the page that contains the SFR’s for the peripheral or function that is the source of the interrupt. SFR Definition 12.2. SFR Page Register: SFRPAGE R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x84 SFR Page: All Pages SFRPAGE: SFR Page Register. Byte represents the SFR page the CIP-51 uses when reading or modifying SFR’s. SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is third entry. The SFRPAGE, SFRSTACK, and SFRLAST bytes may be used alter the context in the SFR Page Stack. Only interrupts and returns from interrupt service routines push and pop the SFR Page Stack. (See Section 12.2.6.2 and Section 12.2.6.3 for further information.) Write: Sets the SFR Page Read: Byte is the SFR page the CIP-51 MCU is using. 142 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.3. SFR Next Register: SFRNEXT 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 Bits7-0: Bit0 SFR Address: 0x85 SFR Page: All Pages SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is third entry. The SFRPAGE, SFRSTACK, and SFRLAST bytes may be used alter the context in the SFR Page Stack. Only interrupts and returns from interrupt service routines push and pop the SFR Page Stack. (See Section 12.2.6.2 and Section 12.2.6.3 for further information.) Write: Sets the SFR Page contained in the second byte of the SFR Stack. This will cause the SFRPAGE SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the second byte of the SFR stack. This is the value that will go to the SFR Page register upon a return from interrupt. SFR Definition 12.4. SFR Last Register: SFRLAST R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x86 SFR Page: All Pages SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page Stack, and will not cause the stack to ‘push’ or ‘pop’. Only interrupts and returns from the interrupt service routine push and pop the SFR Page Stack. Write: Sets the SFR Page in the last entry of the SFR Stack. This will cause the SFRNEXT SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the last entry of the SFR stack. Rev. 1.6 143 C8051F040/1/2/3/4/5/6/7 Table 12.2. Special Function Register (SFR) Memory Map A D D R E S S 0(8) 1(9) 2(A) SPI0CN CAN0CN PCA0L PCA0H 3(B) 4(C) 5(D) 6(E) 7(F) PCA0CPL0 PCA0CPH0 PCA0CPL1 PCA0CPH1 0 WDTCN (ALL PAGES) F8 SFR P A G E P7 1 2 3 F 0 F0 B (ALL PAGES) ADC0CN E8 PCA0CPL2 ADC2CN P6 PCA0CPL5 E0 ACC (ALL PAGES) XBR0 PCA0CN PCA0MD CAN0DATL CAN0DATH D8 P5 REF0CN D0 C8 PSW (ALL PAGES) TMR2CN TMR3CN TMR4CN TMR2CF TMR3CF TMR4CF P4 SMB0CN CAN0STA SMB0STA C0 SADEN0 B8 IP (ALL PAGES) 0(8) 144 1(9) 1 EIP1 EIP2 2 (ALL PAGES) (ALL PAGES) 3 F 0 PCA0CPH2 PCA0CPL3 PCA0CPH3 PCA0CPL4 PCA0CPH4 RSTSRC 1 2 3 F 0 PCA0CPH5 1 EIE1 EIE2 2 (ALL PAGES) (ALL PAGES) 3 F XBR1 XBR2 XBR3 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPM5 0 1 CAN0ADR CAN0TST 2 3 F 0 DAC0L DAC0H DAC0CN HVA0CN 1 DAC1L DAC1H DAC1CN 2 3 F 0 RCAP2L RCAP2H TMR2L TMR2H SMB0CR 1 RCAP3L RCAP3H TMR3L TMR3H 2 RCAP4L RCAP4H TMR4L TMR4H 3 F 0 SMB0DAT SMB0ADR ADC0GTL ADC0GTH ADC0LTL ADC0LTH 1 2 ADC2GT ADC2LT 3 F 0 AMX0CF AMX0SL ADC0CF AMX0PRT ADC0L ADC0H 1 2 AMX2CF AMX2SL ADC2CF ADC2 3 F 2(A) 3(B) 4(C) Rev. 1.6 5(D) 6(E) 7(F) C8051F040/1/2/3/4/5/6/7 Table 12.2. Special Function Register (SFR) Memory Map (Continued) A D D R E S S B0 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F) FLSCL 0 FLACL 1 2 3 F P3MDIN 1 2 3 F P3MDOUT 1 2 3 F P7MDOUT 1 2 3 F P3 (ALL PAGES) SADDR0 A8 0 IE (ALL PAGES) P1MDIN EMI0TC A0 EMI0CN P2MDIN EMI0CF 0 P2 (ALL PAGES) P0MDOUT SCON0 SCON1 SBUF0 SBUF1 SPI0CFG SPI0DAT P1MDOUT SPI0CKR P2MDOUT 0 98 P4MDOUT P5MDOUT P6MDOUT SSTA0 90 88 0 P1 (ALL PAGES) TCON CPT0CN CPT1CN CPT2CN TMOD CPT0MD CPT1MD CPT2MD SFR P A G E TL0 TL1 TH0 OSCICN OSCICL OSCXCN TH1 SFRPGCN CKCON CLKSEL PSCTL 1 2 3 F 0 1 2 3 F 0 1 P0 SP DPL DPH SFRPAGE SFRNEXT SFRLAST PCON 2 80 (ALL PAGES) (ALL PAGES) (ALL PAGES) (ALL PAGES) (ALL PAGES) (ALL PAGES) (ALL PAGES) (ALL PAGES) 3 F 0(8) 1(9) 2(A) 3(B) 4(C) Rev. 1.6 5(D) 6(E) 7(F) 145 C8051F040/1/2/3/4/5/6/7 Table 12.3. Special Function Registers SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address SFR Page Description ACC 0xE0 All Pages Accumulator ADC0CF 0xBC 0 ADC0 Configuration Page No. page 152 ADC0CN 0xE8 0 ADC0 Control page 591, page 812 ADC0GTH 0xC5 0 ADC0 Greater-Than High page 621, page 842 ADC0GTL 0xC4 0 ADC0 Greater-Than Low page 621, page 842 ADC0H 0xBF 0 ADC0 Data Word High page 601, page 822 ADC0L 0xBE 0 ADC0 Data Word Low page 601, page 822 ADC0LTH 0xC7 0 ADC0 Less-Than High page 621, page 842 ADC0LTL 0xC6 0 ADC0 Less-Than Low ADC23 0xBE 2 ADC2 Data Word page 631, page 852 page 99 ADC2CF3 0xBC 2 ADC2 Analog Multiplexer Configuration page 95 ADC2CN3 0xE8 2 ADC2 Control page 98 ADC2GT3 0xC4 2 ADC2 Window Comparator Greater-Than page 100 ADC2LT3 0xC6 2 ADC2 Window Comparator Less-Than page 100 AMX0CF AMX0PRT AMX0SL 0xBA 0xBD 0xBB 0 0 0 ADC0 Multiplexer Configuration ADC0 Port 3 I/O Pin Select ADC0 Multiplexer Channel Select page 491, page 712 page 51 AMX2CF3 0xBA 2 ADC2 Multiplexer Configuration page 491, page 712 page 97 AMX2SL3 DAC0CN3 0xBB 0xF0 0xDA 0xF8 0xD9 0xD8 0xC0 0xDB 0x8E 0x97 0x89 0x89 0x89 0x88 0x88 0x88 0xD4 2 All Pages 1 1 1 1 1 1 0 F 1 2 3 1 2 3 0 ADC2 Multiplexer Channel Select B Register CAN0 Address CAN0 Control CAN0 Data Register High CAN0 Data Register Low CAN0 Status CAN0 Test Register Clock Control Oscillator Clock Selection Register Comparator 0 Mode Selection Comparator 1 Mode Selection Comparator 2 Mode Selection Comparator 0 Control Comparator 1 Control Comparator 2 Control DAC0 Control page 95 page 152 page 213 page 213 page 212 page 212 page 214 page 214 page 295 page 175 page 125 page 125 page 125 page 124 page 124 page 124 page 108 DAC0H3 0xD3 0 DAC0 High page 107 DAC0L3 0xD2 0 DAC0 Low page 107 DAC1CN3 0xD4 1 DAC1 Control page 110 DAC1H3 0xD3 1 DAC1 High Byte page 109 B CAN0ADR CAN0CN CAN0DATH CAN0DATL CAN0STA CAN0TST CKCON CLKSEL CPT0MD CPT1MD CPT2MD CPT0CN CPT1CN CPT2CN 146 Rev. 1.6 page 581, page 802 C8051F040/1/2/3/4/5/6/7 Table 12.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address SFR Page Description DAC1L3 DPH DPL EIE1 EIE2 EIP1 EIP2 EMI0CF EMI0CN EMI0TC FLACL FLSCL HVA0CN IE IP OSCICL OSCICN OSCXCN P0 P0MDOUT P1 P1MDIN P1MDOUT P2 P2MDIN P2MDOUT P3 P3MDIN P3MDOUT Page No. 1 All Pages All Pages All Pages All Pages All Pages All Pages 0 0 0 F 0 0 All Pages All Pages F F F All Pages F All Pages F F All Pages F F All Pages F F F DAC1 Low Byte Data Pointer High Data Pointer Low Extended Interrupt Enable 1 Extended Interrupt Enable 2 Extended Interrupt Priority 1 Extended Interrupt Priority 2 EMIF Configuration External Memory Interface Control EMIF Timing Control Flash Access Limit Flash Scale High Voltage Differential Amp Control Interrupt Enable Interrupt Priority Internal Oscillator Calibration Internal Oscillator Control External Oscillator Control Port 0 Latch Port 0 Output Mode Configuration Port 1 Latch Port 1 Input Mode Configuration Port 1 Output Mode Configuration Port 2 Latch Port 2 Input Mode Configuration Port 2 Output Mode Configuration Port 3 Latch Port 3 Input Mode Configuration Port 3 Output Mode Configuration Port 4 Latch page 109 page 150 page 150 page 159 page 160 page 161 page 162 page 190 page 189 page 195 page 184 page 184 P44 0xD2 0x83 0x82 0xE6 0xE7 0xF6 0xF7 0xA3 0xA2 0xA1 0xB7 0xB7 0xD6 0xA8 0xB8 0x8B 0x8A 0x8C 0x80 0xA4 0x90 0xAD 0xA5 0xA0 0xAE 0xA6 0xB0 0xAF 0xA7 0xC8 P4MDOUT4 0x9C F Port 4 Output Mode Configuration page 222 P54 0xD8 F Port 5 Latch page 223 P5MDOUT4 0x9D F Port 5 Output Mode Configuration page 223 P64 0xE8 F Port 6 Latch page 224 P6MDOUT4 0x9E F Port 6 Output Mode Configuration page 224 P74 0xF8 F Port 7 Latch page 225 P7MDOUT4 0x9F 0xD8 0xFC 0xFE 0xEA 0xEC F 0 0 0 0 0 Port 7 Output Mode Configuration PCA Control PCA Capture 0 High PCA Capture 1 High PCA Capture 2 High PCA Capture 3 High page 225 page 314 page 318 page 318 page 318 page 318 PCA0CN PCA0CPH0 PCA0CPH1 PCA0CPH2 PCA0CPH3 Rev. 1.6 page 531, page 752 page 157 page 158 page 174 page 174 page 176 page 215 page 216 page 216 page 217 page 217 page 218 page 218 page 219 page 219 page 220 page 220 page 222 147 C8051F040/1/2/3/4/5/6/7 Table 12.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address SFR Page Description PCA0CPH4 0xEE 0 PCA Capture 4 High PCA0CPH5 0xE2 0 PCA Capture 5 High PCA0CPL0 0xFB 0 PCA Capture 0 Low PCA0CPL1 0xFD 0 PCA Capture 1 Low PCA0CPL2 0xE9 0 PCA Capture 2 Low PCA0CPL3 0xEB 0 PCA Capture 3 Low PCA0CPL4 0xED 0 PCA Capture 4 Low PCA0CPL5 0xE1 0 PCA Capture 5 Low PCA0CPM0 0xDA 0 PCA Module 0 Mode Register PCA0CPM1 0xDB 0 PCA Module 1 Mode Register PCA0CPM2 0xDC 0 PCA Module 2 Mode Register PCA0CPM3 0xDD 0 PCA Module 3 Mode Register PCA0CPM4 0xDE 0 PCA Module 4 Mode Register PCA0CPM5 0xDF 0 PCA Module 5 Mode Register PCA0H 0xFA 0 PCA Counter High PCA0L 0xF9 0 PCA Counter Low PCA0MD 0xD9 0 PCA Mode PCON 0x87 All Pages Power Control PSCTL 0x8F 0 Program Store R/W Control PSW 0xD0 All Pages Program Status Word RCAP2H 0xCB 0 Timer/Counter 2 Capture/Reload High RCAP2L 0xCA 0 Timer/Counter 2 Capture/Reload Low RCAP3H 0xCB 1 Timer/Counter 3 Capture/Reload High RCAP3L 0xCA 1 Timer/Counter 3 Capture/Reload Low RCAP4H 0xCB 2 Timer/Counter 4 Capture/Reload High RCAP4L 0xCA 2 Timer/Counter 4 Capture/Reload Low REF0CN 0xD1 0 Programmable Voltage Reference Control RSTSRC 0xEF 0 Reset Source Register SADDR0 0xA9 0 UART 0 Slave Address SADEN0 0xB9 0 UART 0 Slave Address Enable SBUF0 0x99 0 UART 0 Data Buffer SBUF1 0x99 1 UART 1 Data Buffer SCON0 0x98 0 UART 0 Control SCON1 0x98 1 UART 1 Control SFRPAGE 0x84 All Pages SFR Page Register SFRPGCN 0x96 F SFR Page Control Register SFRNEXT 0x85 All Pages SFR Next Page Stack Access Register SFRLAST 0x86 All Pages SFR Last Page Stack Access Register SMB0ADR 0xC3 0 SMBus Slave Address SMB0CN 0xC0 0 SMBus Control SMB0CR 0xCF 0 SMBus Clock Rate SMB0DAT 0xC2 0 SMBus Data SMB0STA 0xC1 0 SMBus Status SP 0x81 All Pages Stack Pointer 148 Rev. 1.6 Page No. page 318 page 318 page 318 page 318 page 318 page 318 page 318 page 318 page 316 page 316 page 316 page 316 page 316 page 316 page 317 page 317 page 315 page 164 page 185 page 151 page 303 page 303 page 303 page 303 page 303 page 303 page 1144, page 1185 page 170 page 276 page 276 page 276 page 283 page 274 page 282 page 142 page 142 page 143 page 143 page 250 page 247 page 248 page 249 page 251 page 150 C8051F040/1/2/3/4/5/6/7 Table 12.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved. Register Address SFR Page Description SPI0CFG 0x9A 0 SPI Configuration SPI0CKR 0x9D 0 SPI Clock Rate Control SPI0CN 0xF8 0 SPI Control SPI0DAT 0x9B 0 SPI Data SSTA0 0x91 0 UART0 Status and Clock Selection TCON 0x88 0 Timer/Counter Control TH0 0x8C 0 Timer/Counter 0 High TH1 0x8D 0 Timer/Counter 1 High TL0 0x8A 0 Timer/Counter 0 Low TL1 0x8B 0 Timer/Counter 1 Low TMOD 0x89 0 Timer/Counter Mode TMR2CF 0xC9 0 Timer/Counter 2 Configuration TMR2CN 0xC8 0 Timer/Counter 2 Control TMR2H 0xCD 0 Timer/Counter 2 High TMR2L 0xCC 0 Timer/Counter 2 Low TMR3CF 0xC9 1 Timer/Counter 3 Configuration TMR3CN 0xC8 1 Timer 3 Control TMR3H 0xCD 1 Timer/Counter 3 High TMR3L 0xCC 1 Timer/Counter 3 Low TMR4CF 0xC9 2 Timer/Counter 4 Configuration TMR4CN 0xC8 2 Timer/Counter 4 Control TMR4H 0xCD 2 Timer/Counter 4 High TMR4L 0xCC 2 Timer/Counter 4 Low WDTCN 0xFF All Pages Watchdog Timer Control XBR0 0xE1 F Port I/O Crossbar Control 0 XBR1 0xE2 F Port I/O Crossbar Control 1 XBR2 0xE3 F Port I/O Crossbar Control 2 XBR3 0xE4 F Port I/O Crossbar Control 3 0x97, 0xA2, 0xB3, 0xB4, Reserved 0xCE, 0xDF Page No. page 261 page 263 page 262 page 264 page 275 page 293 page 296 page 296 page 295 page 296 page 294 page 302 page 301 page 304 page 303 page 302 page 301 page 304 page 303 page 302 page 301 page 304 page 303 page 169 page 212 page 213 page 214 page 215 Notes: 1. Refers to a register in the C8051F040 only. 2. Refers to a register in the C8051F041 only. 3. Refers to a register in C8051F040/1/2/3 only. 4. Refers to a register in the C8051F040/2/4/6 only. 5. Refers to a register in the C8051F041/3/5/7 only. Rev. 1.6 149 C8051F040/1/2/3/4/5/6/7 12.2.7. 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 data sheet associated with their corresponding system function. SFR Definition 12.5. SP: Stack Pointer R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000111 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x81 SFR Page: All Pages 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 12.6. DPL: Data Pointer Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x82 SFR Page: All Pages 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 12.7. 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 Bits7-0: 150 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x83 SFR Page: All Pages 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. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.8. PSW: Program Status Word R/W R/W R/W R/W R/W R/W R/W R/W Reset Value CY AC F0 RS1 RS0 OV F1 PARITY 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bits4-3: 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. 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. F0: User Flag 0. This is a bit-addressable, general purpose flag for use under software control. RS1-RS0: Register Bank Select. These bits select which register bank is used during register accesses. RS1 0 0 1 1 Bit2: Bit1: Bit0: Bit Addressable SFR Address: 0xD0 SFR Page: All Pages Bit0 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. 1.6 151 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.9. 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 Bits7-0: Bit Addressable SFR Address: 0xE0 SFR Page: All Pages Bit0 ACC: Accumulator. This register is the accumulator for arithmetic operations. SFR Definition 12.10. 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 Bits7-0: 152 Bit Addressable SFR Address: 0xF0 SFR Page: All Pages Bit0 B: B Register. This register serves as a second accumulator for certain arithmetic operations. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12.3. Interrupt Handler The CIP-51 includes an extended interrupt system supporting a total of 20 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies according to the specific version of the device. Each interrupt source has one or more associated interruptpending 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 an SFR (IE-EIE2). However, interrupts must first be globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-enable settings. Note: Any instruction that clears the EA bit should be immediately followed by an instruction that has two or more opcode bytes. For example: // in 'C': EA = 0; // clear EA bit EA = 0; // ... followed by another 2-byte opcode ; in assembly: CLR EA ; clear EA bit CLR EA ; ... followed by another 2-byte opcode If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. However, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is followed by a multi-cycle instruction, the interrupt will not be taken. Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI) instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction. 12.3.1. MCU Interrupt Sources and Vectors The MCUs support 20 interrupt sources. Software can simulate an interrupt event by setting any interruptpending 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 12.4. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). Rev. 1.6 153 C8051F040/1/2/3/4/5/6/7 12.3.2. External Interrupts The external interrupt sources (/INT0 and /INT1) are configurable as active-low level-sensitive or activelow edge-sensitive inputs depending on the setting of bits IT0 (TCON.0) and IT1 (TCON.2). IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flag for the /INT0 and /INT1 external interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interruptpending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag follows the state of the external interrupt's input pin. 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. Bit addressable? Cleared by HW? SFRPAGE (SFRPGEN = 1) Table 12.4. Interrupt Summary N/A N/A 0 Always Enabled IE0 (TCON.1) Y Y 0 EX0 (IE.0) PX0 (IP.0) 1 TF0 (TCON.5) Y Y 0 ET0 (IE.1) PT0 (IP.1) 0x0013 2 IE1 (TCON.3) Y Y 0 EX1 (IE.2) PX1 (IP.2) 0x001B 3 Y Y 0 ET1 (IE.3) PT1 (IP.3) UART0 0x0023 4 Y 0 ES0 (IE.4) PS0 (IP.4) Timer 2 0x002B 5 Y 0 ET2 (IE.5) PT2 (IP.5) Serial Peripheral Interface 0x0033 6 TF1 (TCON.7) RI0 (SCON0.0) TI0 (SCON0.1) TF2 (TMR2CN.7) SPIF (SPI0CN.7) WCOL (SPI0CN.6) MODF (SPI0CN.5) RXOVRN (SPI0CN.4) Y 0 ESPI0 (EIE1.0) PSPI0 (EIP1.0) SMBus Interface 0x003B 7 SI (SMB0CN.3) Y 0 0x0043 8 Y 0 0x004B 9 Y 0 0x0053 10 ESMB0 (EIE1.1) EWADC0 (EIE1.2) EPCA0 (EIE1.3) CP0IE (EIE1.4) PSMB0 (EIP1.1) PWADC0 (EIP1.2) PPCA0 (EIP1.3) PCP0 (EIP1.4) Interrupt Source Reset External Interrupt 0 (/INT0) Timer 0 Overflow External Interrupt 1 (/INT1) Timer 1 Overflow ADC0 Window Comparator Programmable Counter Array Comparator 0 154 Interrupt Vector Priority Order Pending Flag 0x0000 Top None 0x0003 0 0x000B AD0WINT (ADC0CN.2) CF (PCA0CN.7) CCFn (PCA0CN.n) CP0FIF/CP0RIF (CPT0CN.4/.5) Rev. 1.6 1 Enable Flag Priority Control Always Highest C8051F040/1/2/3/4/5/6/7 Priority Order Pending Flag CP1FIF/CP1RIF (CPT1CN.4/.5) CP2FIF/CP2RIF (CPT2CN.4/.5) Comparator 1 0x005B 11 Comparator 2 0x0063 12 Timer 3 0x0073 14 TF3 (TMR3CN.7) ADC0 End of Conversion 0x007B 15 ADC0INT (ADC0CN.5) Timer 4 0x0083 16 TF4 (TMR4CN.7) 0x0093 17 0x008B 18 CAN Interrupt 0x009B 19 CAN0CN.7 UART1 0x00A3 20 RI1 (SCON1.0) TI1 (SCON1.1) ADC2 Window Comparator ADC2 End of Conversion 2 3 1 Y 0 2 AD2WINT (ADC2CN.0) ADC2INT (ADC1CN.5) Rev. 1.6 SFRPAGE (SFRPGEN = 1) Interrupt Vector Cleared by HW? Interrupt Source Bit addressable? Table 12.4. Interrupt Summary (Continued) 2 2 Y 1 1 Enable Flag Priority Control CP1IE (EIE1.5) CP2IE (EIE1.6) ET3 (EIE2.0) EADC0 (EIE2.1) ET4 (EIE2.2) EWADC2 (EIE2.3) EADC1 (EIE2.4) ECAN0 (EIE2.5) ES1 (EIE2.6) PCP1 (EIP1.5) PCP2 (EIP1.6) PT3 (EIP2.0) PADC0 (EIP2.1) PT4 (EIP2.2) PWADC2 (EIP2.3) PADC1 (EIP2.4) PCAN0 (EIP2.5) PS1 (EIP2.6) 155 C8051F040/1/2/3/4/5/6/7 12.3.3. 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-EIP2) 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 12.4. 12.3.4. Interrupt Latency Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are sampled and priority decoded each system clock cycle. The fastest possible response time is 5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the slowest response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is 18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction. 12.3.5. Interrupt Register Descriptions The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). 156 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.11. IE: Interrupt Enable R/W R/W R/W R/W R/W R/W R/W R/W Reset Value EA IEGF0 ET2 ES0 ET1 EX1 ET0 EX0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit Addressable SFR Address: 0xA8 SFR Page: All Pages Bit0 EA: Enable All Interrupts. 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. IEGF0: General Purpose Flag 0. This is a general purpose flag for use under software control. ET2: Enabler 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 TF2 flag. 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 pin. 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 pin. Rev. 1.6 157 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.12. IP: Interrupt Priority R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - - PT2 PS0 PT1 PX1 PT0 PX0 11000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 158 UNUSED. Read = 11b, Write = don't care. PT2: Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupt priority set to low priority level. 1: Timer 2 interrupts set to high priority level. PS0: UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupt priority set to low priority level. 1: UART0 interrupts 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 priority set to low priority level. 1: Timer 1 interrupts 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 priority 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 priority 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 priority set to low priority level. 1: External Interrupt 0 set to high priority level. Rev. 1.6 Bit Addressable SFR Address: 0xB8 SFR Page: All Pages Bit0 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.13. EIE1: Extended Interrupt Enable 1 R/W Bit7 Bit7: Bit6: Bit6: Bit6: Bit3: Bit2: Bit1: Bit0: R/W R/W R/W R/W R/W R/W R/W Reset Value CP2IE CP1IE CP0IE EPCA0 EWADC0 ESMB0 ESPI0 00000000 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xE6 SFR Page: All Pages Reserved. Read = 0b, Write = don’t care. CP2IE: Enable Comparator (CP2) Interrupt. This bit sets the masking of the CP2 interrupt. 0: Disable CP2 interrupts. 1: Enable interrupt requests generated by the CP2IF flag. CP1IE: Enable Comparator (CP1) Interrupt. This bit sets the masking of the CP1 interrupt. 0: Disable CP1 interrupts. 1: Enable interrupt requests generated by the CP1IF flag. CP0IE: Enable Comparator (CP0) Interrupt. This bit sets the masking of the CP0 interrupt. 0: Disable CP0 interrupts. 1: Enable interrupt requests generated by the CP0IF flag. EPCA0: Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable all PCA0 interrupts. 1: Enable interrupt requests generated by PCA0. EWADC0: Enable Window Comparison ADC0 Interrupt. This bit sets the masking of ADC0 Window Comparison interrupt. 0: Disable ADC0 Window Comparison Interrupt. 1: Enable Interrupt requests generated by ADC0 Window Comparisons. ESMB0: Enable System Management Bus (SMBus0) Interrupt. This bit sets the masking of the SMBus interrupt. 0: Disable all SMBus interrupts. 1: Enable interrupt requests generated by the SI flag. ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of SPI0 interrupt. 0: Disable all SPI0 interrupts. 1: Enable Interrupt requests generated by the SPI0 flag. Rev. 1.6 159 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.14. EIE2: Extended Interrupt Enable 2 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - ES1 ECAN0 EADC2 EWADC2 ET4 EADC0 ET3 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 160 Bit0 SFR Address: 0xE7 SFR Page: All Pages Reserved ES1: Enable UART1 Interrupt. This bit sets the masking of the UART1 interrupt. 0: Disable UART1 interrupt. 1: Enable UART1 interrupt. ECAN0: Enable CAN Controller Interrupt. This bit sets the masking of the CAN Controller Interrupt. 0: Disable CAN Controller Interrupt. 1: Enable interrupt requests generated by the CAN Controller. EADC2: Enable ADC2 End Of Conversion Interrupt (C8051F040/1/2/3 only). This bit sets the masking of the ADC2 End of Conversion interrupt. 0: Disable ADC2 End of Conversion interrupt. 1: Enable interrupt requests generated by the ADC2 End of Conversion Interrupt. EWADC2: Enable Window Comparison ADC2 Interrupt (C8051F040/1/2/3 only). This bit sets the masking of ADC2 Window Comparison interrupt. 0: Disable ADC2 Window Comparison Interrupt. 1: Enable Interrupt requests generated by ADC2 Window Comparisons. ET4: Enable Timer 4 Interrupt This bit sets the masking of the Timer 4 interrupt. 0: Disable Timer 4 interrupt. 1: Enable interrupt requests generated by the TF4 flag. EADC0: Enable ADC0 End of Conversion Interrupt. This bit sets the masking of the ADC0 End of Conversion Interrupt. 0: Disable ADC0 Conversion Interrupt. 1: Enable interrupt requests generated by the ADC0 Conversion Interrupt. ET3: Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable all Timer 3 interrupts. 1: Enable interrupt requests generated by the TF3 flag. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.15. EIP1: Extended Interrupt Priority 1 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - PCP2 PCP1 PCP0 PPCA0 PWADC0 PSMB0 PSPI0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit0 SFR Address: 0xF6 SFR Page: All Pages Reserved. PCP2: Comparator2 (CP2) Interrupt Priority Control. This bit sets the priority of the CP2 interrupt. 0: CP2 interrupt set to low priority level. 1: CP2 interrupt 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. PWADC0: ADC0 Window Comparator Interrupt Priority Control. This bit sets the priority of the ADC0 Window interrupt. 0: ADC0 Window interrupt set to low priority level. 1: ADC0 Window interrupt set to high priority level. PSMB0: System Management Bus (SMBus0) Interrupt Priority Control. This bit sets the priority of the SMBus0 interrupt. 0: SMBus interrupt set to low priority level. 1: SMBus interrupt set to high priority level. 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. Rev. 1.6 161 C8051F040/1/2/3/4/5/6/7 SFR Definition 12.16. EIP2: Extended Interrupt Priority 2 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - EP1 PX7 PADC2 PWADC2 PT4 PADC0 PT3 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 162 Bit0 SFR Address: 0xF7 SFR Page: All Pages Reserved. EP1: UART1 Interrupt Priority Control. This bit sets the priority of the UART1 interrupt. 0: UART1 interrupt set to low level. 1: UART1 interrupt set to high level. PCAN0: CAN Interrupt Priority Control. This bit sets the priority of the CAN Interrupt. 0: CAN Interrupt set to low priority level. 1: CAN Interrupt set to high priority level. PADC2: ADC2 End Of Conversion Interrupt Priority Control (C8051F040/1/2/3 only). This bit sets the priority of the ADC2 End of Conversion interrupt. 0: ADC2 End of Conversion interrupt set to low level. 1: ADC2 End of Conversion interrupt set to low level. PWADC2: ADC2 Window Comparator Interrupt Priority Control (C8051F040/1/2/3 only). 0: ADC2 Window interrupt set to low level. 1: ADC2 Window interrupt set to high level. PT4: Timer 4 Interrupt Priority Control. This bit sets the priority of the Timer 4 interrupt. 0: Timer 4 interrupt set to low level. 1: Timer 4 interrupt set to low level. PADC0: ADC End of Conversion Interrupt Priority Control. This bit sets the priority of the ADC0 End of Conversion Interrupt. 0: ADC0 End of Conversion interrupt set to low priority level. 1: ADC0 End of Conversion interrupt set to high priority level. PT3: Timer 3 Interrupt Priority Control. This bit sets the priority of the Timer 3 interrupts. 0: Timer 3 interrupt set to low priority level. 1: Timer 3 interrupt set to high priority level. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 12.17. 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 external 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. 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 12.18 describes the Power Control Register (PCON) used to control the CIP51'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 put into low power mode. Digital peripherals, such as timers or serial buses, draw little power whenever they are not in use. Turning off the oscillator saves even more power, but requires a reset to restart the MCU. 12.17.1.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. 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 or /RST is asserted. 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 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. Refer to Section 13.7 for more information on the use and configuration of the WDT. Note: Any instruction that sets the IDLE bit should be immediately followed by an instruction that has 2 or more opcode bytes. For example: // in 'C': PCON |= 0x01; PCON = PCON; // set IDLE bit // ... followed by a 3-cycle dummy instruction ; in assembly: ORL PCON, #01h MOV PCON, PCON ; set IDLE bit ; ... followed by a 3-cycle dummy instruction If the instruction following the write of the IDLE bit is a single-byte instruction and an interrupt occurs during the execution phase of the instruction that sets the IDLE bit, the CPU may not wake from IDLE mode when a future interrupt occurs. Rev. 1.6 163 C8051F040/1/2/3/4/5/6/7 12.17.2.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. In Stop mode, the CPU and internal oscillators are stopped, effectively shutting down all digital peripherals. Each analog peripheral must 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 sleep for longer than the MCD timeout of 100 μs. SFR Definition 12.18. PCON: Power Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value — — — — — — STOP IDLE 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-3: Bit1: Bit0: 164 Bit0 SFR Address: 0x87 SFR Page: All Pages Reserved. STOP: STOP Mode Select. Writing a ‘1’ to this bit will place the CIP-51 into STOP mode. This bit will always read ‘0’. 0: No effect. 1: CIP-51 forced into power-down mode. (Turns off internal oscillator). IDLE: IDLE Mode Select. Writing a ‘1’ to this bit will place the CIP-51 into IDLE mode. This bit will always read ‘0’. 0: No effect. 1: CIP-51 forced into idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, and all peripherals remain active.) Rev. 1.6 C8051F040/1/2/3/4/5/6/7 13. 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 are not altered. The I/O port latches are reset to 0xFF (all logic 1s), activating internal weak pullups which take the external I/O pins to a high state. For VDD Monitor resets, the /RST pin is driven low until the end of the VDD reset timeout. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator running at its lowest frequency. Refer to Section “14. Oscillators” on page 173 for information on selecting and configuring the system clock source. The Watchdog Timer is enabled using its longest timeout interval (see Section “13.7. Watchdog Timer Reset” on page 167). Once the system clock source is stable, program execution begins at location 0x0000. There are seven sources for putting the MCU into the reset state: power-on, power-fail, external /RST pin, external CNVSTR0 signal, software command, Comparator0, Missing Clock Detector, and Watchdog Timer. Each reset source is described in the following sections. Figure 13.1. Reset Sources Rev. 1.6 165 C8051F040/1/2/3/4/5/6/7 13.1. Power-On Reset The C8051F04x family incorporates a power supply monitor that holds the MCU in the reset state until VDD rises above the VRST level during power-up. See Figure 13.2 for timing diagram, and refer to Table 13.1 for the Electrical Characteristics of the power supply monitor circuit. The /RST pin is asserted low until the end of the 100 ms VDD Monitor timeout in order to allow the VDD supply to stabilize. The VDD Monitor reset is enabled and disabled using the external VDD monitor enable pin (MONEN). On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. 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. Figure 13.2. Reset Timing 13.2. Power-Fail Reset When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply monitor will drive the /RST pin low and return the CIP-51 to the reset state. When VDD returns to a level above VRST, the CIP-51 will leave the reset state in the same manner as that for the power-on reset (see Figure 13.2). 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 is set to logic 1, the data may no longer be valid. 13.3. External Reset The external /RST pin provides a means for external circuitry to force the MCU into a reset state. Asserting the /RST pin low will cause the MCU to enter the reset state. It may be desirable to provide an external pul- 166 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 lup and/or decoupling of the /RST pin to avoid erroneous noise-induced resets. The MCU will remain in reset until at least 12 clock cycles after the active-low /RST signal is removed. The PINRSF flag (RSTSRC.0) is set on exit from an external reset. 13.4. Missing Clock Detector Reset The Missing Clock Detector is essentially a one-shot circuit that is triggered by the MCU system clock. If the system clock goes away for more than 100 μs, the one-shot will time out and generate a reset. After a Missing Clock Detector reset, the MCDRSF flag (RSTSRC.2) will be set, signifying the MCD as the reset source; otherwise, this bit reads ‘0’. The state of the /RST pin is unaffected by this reset. Setting the MCDRSF bit, RSTSRC.2 (see Section “14. Oscillators” on page 173) enables the Missing Clock Detector. 13.5. Comparator0 Reset Comparator0 can be configured as a reset input by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled using CPT0CN.7 (see Section “11. Comparators” on page 121) 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 (CP0+ pin) is less than the inverting input voltage (CP0- pin), the MCU is put into the reset state. After a Comparator0 Reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset source; otherwise, this bit reads ‘0’. The state of the /RST pin is unaffected by this reset. 13.6. External CNVSTR0 Pin Reset The external CNVSTR0 signal can be configured as a reset input by writing a ‘1’ to the CNVRSEF flag (RSTSRC.6). The CNVSTR0 signal can appear on any of the P0, P1, P2 or P3 I/O pins as described in Section “17.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 204. Note that the Crossbar must be configured for the CNVSTR0 signal to be routed to the appropriate Port I/O. The Crossbar should be configured and enabled before the CNVRSEF is set. When configured as a reset, CNVSTR0 is active-low and level sensitive. After a CNVSTR0 reset, the CNVRSEF flag (RSTSRC.6) will read ‘1’ signifying CNVSTR0 as the reset source; otherwise, this bit reads ‘0’. The state of the /RST pin is unaffected by this reset. 13.7. Watchdog Timer Reset The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. A WDT overflow will force the MCU into the reset state. To prevent the reset, the WDT must be restarted by application software before overflow. If the system experiences a software or hardware malfunction preventing the software from restarting the WDT, the WDT will overflow and cause a reset. This should prevent the system from running out of control. Following a reset the WDT is automatically enabled and running with the default maximum time interval. If desired the WDT can be disabled by system software or locked on to prevent accidental disabling. Once locked, the WDT cannot be disabled until the next system reset. The state of the /RST pin is unaffected by this reset. The WDT consists of a 21-bit timer running from the programmed system clock. The timer measures the period between specific writes to its control register. If this period exceeds the programmed limit, a WDT reset is generated. The WDT can be enabled and disabled as needed in software, or can be permanently enabled if desired. Watchdog features are controlled via the Watchdog Timer Control Register (WDTCN) shown in SFR Definition 13.1. Rev. 1.6 167 C8051F040/1/2/3/4/5/6/7 13.7.1. Enable/Reset WDT The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's application software should include periodic writes of 0xA5 to WDTCN as needed to prevent a watchdog timer overflow. The WDT is enabled and reset as a result of any system reset. 13.7.2. Disable WDT Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment illustrates disabling the WDT: CLR MOV MOV SETB EA WDTCN,#0DEh WDTCN,#0ADh EA ; disable all interrupts ; disable software watchdog timer ; re-enable interrupts The writes of 0xDE and 0xAD must occur within 4 clock cycles of each other, or the disable operation is ignored. Interrupts should be disabled during this procedure to avoid delay between the two writes. 13.7.3. Disable WDT Lockout Writing 0xFF to WDTCN locks out the disable feature. Once locked out, the disable operation is ignored until the next system reset. Writing 0xFF does not enable or reset the watchdog timer. Applications always intending to use the watchdog should write 0xFF to WDTCN in the initialization code. 13.7.4. Setting WDT Interval WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equation: 4 3 + WDTCN  2 – 0   T sysclk ; where Tsysclk is the system clock period. For a 3 MHz system clock, this provides an interval range of 0.021 ms to 349.5 ms. WDTCN.7 must be logic 0 when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] reads 111b after a system reset. 168 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 13.1. WDTCN: Watchdog Timer Control 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 xxxxx111 Bits7-0: Bit4: Bits2-0: Bit0 SFR Address: 0xFF SFR Page: All Pages WDT Control Writing 0xA5 both enables and reloads the WDT. Writing 0xDE followed within 4 system clocks by 0xAD disables the WDT. Writing 0xFF locks out the disable feature. Watchdog Status Bit (when Read) Reading the WDTCN.[4] bit indicates the Watchdog Timer Status. 0: WDT is inactive 1: WDT is active Watchdog Timeout Interval Bits The WDTCN.[2:0] bits set the Watchdog Timeout Interval. When writing these bits, WDTCN.7 must be set to 0. Rev. 1.6 169 C8051F040/1/2/3/4/5/6/7 SFR Definition 13.2. RSTSRC: Reset Source R Bit7 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 170 R/W R/W R/W R R/W CNVRSEF C0RSEF SWRSEF WDTRSF MCDRSF Bit6 Bit5 Bit4 Bit3 Bit2 R R/W Reset Value PORSF PINRSF 00000000 Bit1 Bit0 SFR Address: 0xEF SFR Page: 0 Reserved. CNVRSEF: Convert Start Reset Source Enable and Flag Write: 0: CNVSTR0 is not a reset source. 1: CNVSTR0 is a reset source (active low). Read: 0: Source of prior reset was not CNVSTR0. 1: Source of prior reset was CNVSTR0. C0RSEF: Comparator0 Reset Enable and Flag. Write: 0: Comparator0 is not a reset source. 1: Comparator0 is a reset source (active low). Read: 0: Source of last reset was not Comparator0. 1: Source of last reset was Comparator0. SWRSF: Software Reset Force and Flag. Write: 0: No effect. 1: Forces an internal reset. /RST pin is not effected. Read: 0: Source of last reset was not a write to the SWRSF bit. 1: Source of last reset was a write to the SWRSF bit. WDTRSF: Watchdog Timer Reset Flag. 0: Source of last reset was not WDT timeout. 1: Source of last reset was WDT timeout. MCDRSF: Missing Clock Detector Flag. Write: 0: Missing Clock Detector disabled. 1: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected. Read: 0: Source of last reset was not a Missing Clock Detector timeout. 1: Source of last reset was a Missing Clock Detector timeout. PORSF: Power-On Reset Flag. Write: If the VDD monitor circuitry is enabled (by tying the MONEN pin to a logic high state), this bit can be written to select or de-select the VDD monitor as a reset source. 0: De-select the VDD monitor as a reset source. 1: Select the VDD monitor as a reset source. Important: At power-on, the VDD monitor is enabled/disabled using the external VDD monitor enable pin (MONEN). The PORSF bit does not disable or enable the VDD monitor circuit. It simply selects the VDD monitor as a reset source. Read: This bit is set whenever a power-on reset occurs. This may be due to a true power-on reset or a VDD monitor reset. In either case, data memory should be considered indeterminate following the reset. 0: Source of last reset was not a power-on or VDD monitor reset. 1: Source of last reset was a power-on or VDD monitor reset. Note: When this flag is read as '1', all other reset flags are indeterminate. PINRSF: HW Pin Reset Flag. Write: 0: No effect. 1: Forces a Power-On Reset. /RST is driven low. Read: 0: Source of prior reset was not /RST pin. 1: Source of prior reset was /RST pin. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 13.1. Reset Electrical Characteristics –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units IOL = 8.5 mA, VDD = 2.7 V to 3.6 V — — 0.6 V RST Input High Voltage 0.7 x VDD — — V RST Input Low Voltage — — 0.3 x VDD — 50 — μA VDD for /RST Output Valid 1.0 — — V AV+ for /RST Output Valid 1.0 — — V VDD POR Threshold (VRST) 2.40 2.55 2.70 V Minimum /RST Low Time to Generate a System Reset 10 — — ns RST Output Low Voltage RST Input Leakage Current RST = 0.0 V Reset Time Delay RST rising edge after VDD crosses VRST threshold 80 100 120 ms Missing Clock Detector Timeout Time from last system clock to reset initiation 100 220 500 μs Rev. 1.6 171 C8051F040/1/2/3/4/5/6/7 14. Oscillators Figure 14.1. Oscillator Diagram 14.1. Programmable Internal Oscillator All C8051F04x 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 as defined by SFR Definition 14.1. OSCICL is factory calibrated to obtain a 24.5 MHz frequency. Electrical specifications for the precision internal oscillator are given in Table 14.1 on page 175. The programmed internal oscillator frequency must not exceed 25 MHz. The system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register OSCICN. Rev. 1.6 173 C8051F040/1/2/3/4/5/6/7 SFR Definition 14.1. OSCICL: Internal Oscillator Calibration 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 Variable Bit0 SFR Address: 0x8B SFR Page: F Bits 7-0: OSCICL: Internal Oscillator Calibration Register This register calibrates the internal oscillator period. The reset value for OSCICL defines the internal oscillator base frequency. The reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz. SFR Definition 14.2. OSCICN: Internal Oscillator Control R/W R/W R/W R R/W R/W R/W R/W Reset Value IOSCEN IFRDY - - - - IFCN1 IFCN0 11000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bits5-2: Bits1-0: 174 IOSCEN: Internal Oscillator Enable Bit. 0: Internal Oscillator Disabled 1: Internal Oscillator Enabled IFRDY: Internal Oscillator Frequency Ready Flag. 0: Internal Oscillator is not running at programmed frequency. 1: Internal Oscillator is running at programmed frequency. Reserved. IFCN1-0: Internal Oscillator Frequency Control Bits. 00: SYSCLK derived from Internal Oscillator divided by 8. 01: SYSCLK derived from Internal Oscillator divided by 4. 10: SYSCLK derived from Internal Oscillator divided by 2. 11: SYSCLK derived from Internal Oscillator divided by 1. Rev. 1.6 Bit0 SFR Address: 0x8A SFR Page: F C8051F040/1/2/3/4/5/6/7 Table 14.1. Internal Oscillator Electrical Characteristics –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units Calibrated Internal Oscillator Frequency 24 24.5 25 MHz Internal Oscillator Supply Current OSCICN.7 = 1 (from VDD) — 450 — μA External Clock Frequency 0 — 30 MHz TXCH (External Clock High Time) 15 — — ns TXCL (External Clock Low Time) 15 — — ns 14.2. 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 14.1. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 and/or XTAL1 pin(s) as shown in Option 2, 3, or 4 of Figure 14.1. 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 14.4). 14.3. System Clock Selection The CLKSL bit in register CLKSEL selects which oscillator is used as the system clock. CLKSL must be set to ‘1’ for the system clock to run from the external oscillator; however the external oscillator may still clock peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The system clock may be switched on-the-fly between the internal and external oscillator, so long as the selected oscillator is enabled and has settled. The internal oscillator requires little start-up time and may be enabled and selected as the system clock in the same write to OSCICN. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use as the system clock. 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. SFR Definition 14.3. CLKSEL: Oscillator Clock Selection R R R R R R R R/W Reset Value CLKSL 00000000 - - - - - - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-1: Bit0: Bit0 SFR Address: 0x97 SFR Page: F Reserved. CLKSL: System Clock Source Select Bit. 0: SYSCLK derived from the Internal Oscillator, and scaled as per the IFCN bits in OSCICN. 1: SYSCLK derived from the External Oscillator circuit. Rev. 1.6 175 C8051F040/1/2/3/4/5/6/7 SFR Definition 14.4. OSCXCN: External Oscillator Control R R/W R/W R/W XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 Bit7 Bit7: Bits6-4: Bit3: Bits2-0: Bit6 Bit5 Bit4 R R/W R/W R/W Reset Value - XFCN2 XFCN1 XFCN0 00000000 Bit3 Bit2 Bit1 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. XOSCMD2-0: External Oscillator Mode Bits. 00x: External Oscillator circuit off. 010: External CMOS Clock Mode (External CMOS Clock input on XTAL1 pin). 011: External CMOS Clock Mode with divide by 2 stage (External CMOS Clock input on XTAL1 pin). 10x: RC/C Oscillator Mode with divide by 2 stage. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. RESERVED. Read = 0, Write = don't care. 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  32 kHz 32 kHz f 84 kHz 84 kHz  f 225 kHz 225 kHz  f 590 kHz 590 kHz  f 1.5 MHz 1.5 MHz  f 4 MHz 4 MHz  f 10 MHz 10 MHz  f 30 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 14.1, Option 1; XOSCMD = 11x) Choose XFCN value to match crystal frequency. RC MODE (Circuit from Figure 14.1, Option 2; XOSCMD = 10x) Choose XFCN value to match frequency range: f = 1.23(103) / (R x C), where f = frequency of oscillation in MHz C = capacitor value in pF R = Pullup resistor value in k C MODE (Circuit from Figure 14.1, Option 3; XOSCMD = 10x) Choose K Factor (KF) for the oscillation frequency desired: f = KF / (C x VDD), where f = frequency of oscillation in MHz C = capacitor value on XTAL1, XTAL2 pins in pF VDD = Power Supply on MCU in volts 176 Bit0 SFR Address: 0x8C SFR Page: F Rev. 1.6 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 C8051F040/1/2/3/4/5/6/7 14.4. 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 14.1, Option 1. The External Oscillator Frequency Control value (XFCN) should be chosen from the Crystal column of the table in SFR Definition 14.4 (OSCXCN register). For example, an 11.0592 MHz crystal requires an XFCN setting of 111b. When the crystal oscillator is enabled, the oscillator amplitude detection circuit requires a settle time to achieve proper bias. Introducing a delay of at least 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. Enable the external oscillator in crystal oscillator mode. 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 14.1, 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 14.2.  Figure 14.2. 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. Rev. 1.6 177 C8051F040/1/2/3/4/5/6/7 14.5. External RC Example If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 14.1, 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 14.4, the required XFCN setting is 010b. 14.6. External Capacitor Example If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in Figure 14.1, 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 desired frequency of oscillation and find the capacitor to be used from the equations below. Assume VDD = 3.0 V and f = 50 kHz: f = KF / ( C x VDD ) = KF / ( C x 3 ) = 0.050 MHz If a frequency of roughly 50 kHz is desired, select the K Factor from the table in SFR Definition 14.4 as KF = 7.7: 0.050 MHz = 7.7 / (C x 3) C x 3 = 7.7 / 0.050 = 154, so C = 154 / 3 pF = 51.3 pF Therefore, the XFCN value to use in this example is 010b. 178 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Rev. 1.6 179 C8051F040/1/2/3/4/5/6/7 15. Flash Memory The C8051F04x family includes 64 kB + 128 (C8051F040/1/2/3/4/5) or 32 kB + 128 (C8051F046/7) of onchip, reprogrammable Flash memory for program code and non-volatile data storage. The Flash memory can be programmed in-system, a single byte at a time, through the JTAG interface or by software using the MOVX write instructions. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. The bytes would typically be erased (set to 0xFF) before being reprogrammed. Flash write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. The CPU is stalled during write/erase operations while the device peripherals remain active. Interrupts that occur during Flash write/erase operations are held, and are then serviced in their priority order once the Flash operation has completed. Refer to Table 15.1 for the electrical characteristics of the Flash memory. 15.1. Programming The Flash Memory The simplest means of programming the Flash memory is through the JTAG interface using programming tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initialized device. For details on the JTAG commands to program Flash memory, see Section “25.2. Flash Programming Commands” on page 323. 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 setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1. This directs the MOVX writes to Flash memory instead of to XRAM, which is the default target. The PSWE bit remains set until cleared by software. To avoid errant Flash writes, it is recommended that interrupts be disabled while the PSWE bit is logic 1. Flash memory is read using the MOVC instruction. MOVX reads are always directed to XRAM, regardless of the state of PSWE. Note: To ensure the integrity of Flash memory contents, it is strongly recommended that the on-chip VDD monitor be enabled by connecting the VDD monitor enable pin (MONEN) to VDD in any system that executes code that writes and/or erases Flash memory from software. See “Reset Sources” on page 165 for more information. A write to Flash memory can clear bits but cannot set them; only an erase operation can set bits in Flash. A byte location to be programmed must be erased before a new value can be 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). The following steps illustrate the algorithm for programming Flash by user software. Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Step 7. Step 8. Step 9. Disable interrupts. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software. Set PSEE (PSCTL.1) to enable Flash erases. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flash. Use the MOVX command to write a data byte to any location within the 512-byte page to be erased. Clear PSEE to disable Flash erases Use the MOVX command to write a data byte to the desired byte location within the erased 512-byte page. Repeat this step until all desired bytes are written (within the target page). Clear the PSWE bit to redirect MOVX commands to the XRAM data space. Re-enable interrupts. Write/Erase timing is automatically controlled by hardware. Note that code execution in the 8051 is stalled while the Flash is being programmed or erased. Note that 512 bytes at locations 0xFE00 (C8051F040/1/2/ Rev. 1.6 179 C8051F040/1/2/3/4/5/6/7 3/4/5) and all locations above 0x8000 (C8051F046/7) are reserved. Flash writes and erases targeting the reserved area should be avoided. Table 15.1. Flash Electrical Characteristics VDD = 2.7 to 3.6 V; Ta = –40 to +85 °C Parameter Flash Size1 Conditions Min Typ Max 656642 C8051F040/1/2/3/4/5 C8051F046/7 Units Bytes 20 k 32896 100 k — Erase/Write Erase Cycle Time 10 12 14 ms Write Cycle Time 40 50 60 μs Endurance Notes: 1. Includes 128-byte scratchpad. 2. 512 bytes at locations 0xFE00 to 0xFFFF are reserved. 15.2. 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 (as described in the previous section) and read using the MOVC instruction. An additional 128-byte sector of Flash memory is included for non-volatile data storage. Its smaller sector size makes it particularly well suited as general purpose, non-volatile scratchpad memory. Even though Flash memory can be written a single byte at a time, an entire sector must be erased first. In order to change a single byte of a multi-byte data set, the data must be moved to temporary storage. The 128-byte sector-size facilitates updating data without wasting program memory or RAM space. The 128-byte sector is double-mapped over the 64k byte Flash memory; its address ranges from 0x00 to 0x7F (see Figure 15.1). To access this 128-byte sector, the SFLE bit in PSCTL must be set to logic 1. Code execution from this 128-byte scratchpad sector is not permitted. 15.3. Security Options The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as prevent the viewing of proprietary program code and constants. The Program Store Write Enable (PSCTL.0) and the Program Store Erase Enable (PSCTL.1) bits protect the Flash memory from accidental modification by software. These bits must be explicitly set to logic 1 before software can write or erase the Flash memory. Additional security features prevent proprietary program code and data constants from being read or altered across the JTAG interface or by software running on the system controller. A set of security lock bytes stored at 0xFDFE and 0xFDFF (C8051F040/1/2/3/4/5) and at 0x7FFE and 0x7FFF (C8051F046/7) protect the Flash program memory from being read or altered across the JTAG interface. Each bit in a security lock-byte protects one 8k-byte block of memory. Clearing a bit to logic 0 in a Read Lock Byte prevents the corresponding block of Flash memory from being read across the JTAG interface. Clearing a bit in the Write/Erase Lock Byte protects the block from JTAG erasures and/or writes. The Read Lock Byte is at locations 0xFDFF (C8051F040/1/2/3/4/5) and 0x7FFF (C8051F046/7). The Write/Erase Lock Byte is located at 0xFDFE (C8051F040/1/2/3/4/5) and 0x7FFE (C8051F046/7). Figure 15.1 shows the location and bit definitions of the security bytes. The 512-byte sector containing the lock bytes can be written to, but not erased by software. An attempted read of a read-locked byte returns undefined data. Debugging code in a read-locked sector is not possible through the JTAG interface. 180 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Flash Read Lock Byte Bits7-0: Each bit locks a corresponding block of memory. (Bit7 is MSB). 0: Read operations are locked (disabled) for corresponding block across the JTAG interface. 1: Read operations are unlocked (enabled) for corresponding block across the JTAG interface. Flash Write/Erase Lock Byte Bits7-0: Each bit locks a corresponding block of memory. 0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG interface. 1: Write/Erase operations are unlocked (enabled) for corresponding block across the JTAG interface. NOTE: When the highest block is locked, the security bytes may be written but not erased. Flash access Limit Register (FLACL) The content of this register is used as the high byte of the 16-bit Software Read Limit address. This 16-bit read limit address value is calculated as 0xNN00 where NN is replaced by content of this register on reset. Software running at or above this address is prohibited from using the MOVX and MOVC instructions to read, write, or erase Flash locations below this address. Any attempts to read locations below this limit will return the value 0x00. Figure 15.1. Flash Program Memory Map and Security Bytes Rev. 1.6 181 C8051F040/1/2/3/4/5/6/7 The lock bits can always be read and cleared to logic 0 regardless of the security setting applied to the block containing the security bytes. This allows additional blocks to be protected after the block containing the security bytes has been locked. Important Note: The only means of removing a lock once set is to erase the entire program memory space by performing a JTAG erase operation (i.e., cannot be done in user firmware). Addressing either security byte while performing a JTAG erase operation will automatically initiate erasure of the entire program memory space (except for the reserved area). This erasure can only be performed via JTAG. If a non-security byte in the 0xFBFF-0xFDFF (C8051F040/1/2/3/4/5) or 0x7DFF-0x7FFF (C8051F046/7) page is addressed during the JTAG erasure, only that page (including the security bytes) will be erased. The Flash Access Limit security feature (see Figure 15.1) protects proprietary program code and data from being read by software running on the C8051F04x. This feature provides support for OEMs that wish to program the MCU with proprietary value-added firmware before distribution. The value-added firmware can be protected while allowing additional code to be programmed in remaining program memory space later. The Software Read Limit (SRL) is a 16-bit address that establishes two logical partitions in the program memory space. The first is an upper partition consisting of all the program memory locations at or above the SRL address, and the second is a lower partition consisting of all the program memory locations starting at 0x0000 up to (but excluding) the SRL address. Software in the upper partition can execute code in the lower partition, but is prohibited from reading locations in the lower partition using the MOVC instruction. (Executing a MOVC instruction from the upper partition with a source address in the lower partition will always return a data value of 0x00.) Software running in the lower partition can access locations in both the upper and lower partition without restriction. The Value-added firmware should be placed in the lower partition. On reset, control is passed to the valueadded firmware via the reset vector. Once the value-added firmware completes its initial execution, it branches to a predetermined location in the upper partition. If entry points are published, software running in the upper partition may execute program code in the lower partition, but it cannot read the contents of the lower partition. Parameters may be passed to the program code running in the lower partition either through the typical method of placing them on the stack or in registers before the call or by placing them in prescribed memory locations in the upper partition. The SRL address is specified using the contents of the Flash Access Register. The 16-bit SRL address is calculated as 0xNN00, where NN is the contents of the SRL Security Register. Thus, the SRL can be located on 256-byte boundaries anywhere in program memory space. However, the 512-byte erase sector size essentially requires that a 512 boundary be used. The contents of a non-initialized SRL security byte is 0x00, thereby setting the SRL address to 0x0000 and allowing read access to all locations in program memory space by default. 182 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 15.3.1. Summary of Flash Security Options There are three Flash access methods supported on the C8051F04x devices; 1) Accessing Flash through the JTAG debug interface, 2) Accessing Flash from firmware residing below the Flash Access Limit, and 3) Accessing Flash from firmware residing at or above the Flash Access Limit. Accessing Flash through the JTAG debug interface: 1. The Read and Write/Erase Lock bytes (security bytes) provide security for Flash access through the JTAG interface. 2. Any unlocked page may be read from, written to, or erased. 3. Locked pages cannot be read from, written to, or erased. 4. Reading the security bytes is always permitted. 5. Locking additional pages by writing to the security bytes is always permitted. 6. If the page containing the security bytes is unlocked, it can be directly erased. Doing so will reset the security bytes and unlock all pages of Flash. 7. If the page containing the security bytes is locked, it cannot be directly erased. To unlock the page containing the security bytes, a full JTAG device erase is required. A full JTAG device erase will erase all Flash pages, including the page containing the security bytes and the security bytes themselves. 8. The Reserved Area cannot be read from, written to, or erased at any time. Accessing Flash from firmware residing below the Flash Access Limit: 1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user firmware. 2. Any page of Flash except the page containing the security bytes may be read from, written to, or erased. 3. The page containing the security bytes cannot be erased. Unlocking pages of Flash can only be performed via the JTAG interface. 4. The page containing the security bytes may be read from or written to. Pages of Flash can be locked from JTAG access by writing to the security bytes. 5. The Reserved Area cannot be read from, written to, or erased at any time. Accessing Flash from firmware residing at or above the Flash Access Limit: 1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user firmware. 2. Any page of Flash at or above the Flash Access Limit except the page containing the security bytes may be read from, written to, or erased. 3. Any page of Flash below the Flash Access Limit cannot be read from, written to, or erased. 4. Code branches to locations below the Flash Access Limit are permitted. 5. The page containing the security bytes cannot be erased. Unlocking pages of Flash can only be performed via the JTAG interface. 6. The page containing the security bytes may be read from or written to. Pages of Flash can be locked from JTAG access by writing to the security bytes. 7. The Reserved Area cannot be read from, written to, or erased at any time. Rev. 1.6 183 C8051F040/1/2/3/4/5/6/7 SFR Definition 15.1. FLACL: Flash Access Limit R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: SFR Address: 0xB7 SFR Page: F Bits 7-0: FLACL: Flash Access Limit. This register holds the high byte of the 16-bit program memory read/write/erase limit address. The entire 16-bit access limit address value is calculated as 0xNN00 where NN is replaced by contents of FLACL. A write to this register sets the Flash Access Limit. This register can only be written once after any reset. Any subsequent writes are ignored until the next reset. SFR Definition 15.2. FLSCL: Flash Memory Control R/W R/W FOSE FRAE Bit7 Bit6 Bit7: Bit6: Bits5-1: Bit0: 184 R/W R/W R/W R/W R/W Reserved Reserved Reserved Reserved Reserved Bit5 Bit4 Bit3 Bit2 Bit1 FOSE: Flash One-Shot Timer Enable This is the timer that turns off the sense amps after a Flash read. 0: Flash One-Shot Timer disabled. 1: Flash One-Shot Timer enabled (recommended setting). FRAE: Flash Read Always Enable 0: Flash reads occur as necessary (recommended setting). 1: Flash reads occur every system clock cycle. RESERVED. Read = 00000b. Must Write 00000b. FLWE: Flash Write/Erase Enable This bit must be set to allow Flash writes/erases from user software. 0: Flash writes/erases disabled. 1: Flash writes/erases enabled. Rev. 1.6 R/W Reset Value FLWE 10000000 Bit0 SFR Address: SFR Address: 0xB7 SFR Page: 0 C8051F040/1/2/3/4/5/6/7 SFR Definition 15.3. PSCTL: Program Store Read/Write Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value PSWE 00000000 - - - - - SFLE PSEE Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-3: Bit2: Bit1: Bit0: Bit0 SFR Address: SFR Address: 0x8F SFR Page: 0 UNUSED. Read = 00000b, Write = don't care. SFLE: Scratchpad Flash Memory Access Enable When this bit is set, Flash reads and writes from user software are directed to the 128-byte Scratchpad Flash sector. When SFLE is set to logic 1, Flash accesses out of the address range 0x00-0x7F should not be attempted. Reads/Writes out of this range will yield undefined results. 0: Flash access from user software directed to the Program/Data Flash sector. 1: Flash access from user software directed to the 128 byte Scratchpad sector. PSEE: Program Store Erase Enable. Setting this bit allows an entire page of the Flash program memory to be erased provided the PSWE bit is also set. After setting this bit, 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. Note: The Flash page containing the Read Lock Byte and Write/Erase Lock Bytes cannot be erased by software. 0: Flash program memory erasure disabled. 1: Flash program memory erasure enabled. 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 location must be erased prior to writing data. 0: Write to Flash program memory disabled. MOVX write operations target External RAM. 1: Write to Flash program memory enabled. MOVX write operations target Flash memory. Rev. 1.6 185 C8051F040/1/2/3/4/5/6/7 16. External Data Memory Interface and On-Chip XRAM The C8051F04x MCUs include 4 kB of on-chip RAM mapped into the external data memory space (XRAM), as well as an External Data Memory Interface which can be used to access off-chip memories and memory-mapped devices connected to the GPIO ports. The external memory space may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using the MOVX indirect addressing mode using R0 or R1. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in SFR Definition 16.1). Note: the MOVX instruction can also be used for writing to the Flash memory. See Section “15. Flash Memory” on page 179 for details. The MOVX instruction accesses XRAM by default. The EMIF can be configured to appear on the lower GPIO Ports (P0-P3) or the upper GPIO Ports (P4-P7). 16.1. Accessing XRAM The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms, both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit register which contains the effective address of the XRAM location to be read from or written to. The second method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM address. Examples of both of these methods are given below. 16.1.1. 16-Bit MOVX Example The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the accumulator A: MOV MOVX DPTR, #1234h A, @DPTR ; load DPTR with 16-bit address to read (0x1234) ; load contents of 0x1234 into accumulator A The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately, the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and DPL, which contains the lower 8-bits of DPTR. 16.1.2. 8-Bit MOVX Example The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the effective address to be accessed. The following series of instructions read the contents of the byte at address 0x1234 into the accumulator A. MOV MOV MOVX EMI0CN, #12h R0, #34h a, @R0 ; load high byte of address into EMI0CN ; load low byte of address into R0 (or R1) ; load contents of 0x1234 into accumulator A Rev. 1.6 187 C8051F040/1/2/3/4/5/6/7 16.2. Configuring the External Memory Interface Configuring the External Memory Interface consists of five steps: 1. 2. 3. 4. Select EMIF on Low Ports (P3, P2, P1, and P0) or High Ports (P7, P6, P5, and P4). Configure the Output Modes of the port pins as either push-pull or open-drain. Select Multiplexed mode or Non-multiplexed mode. Select the memory mode (on-chip only, split mode without bank select, split mode with bank select, or off-chip only). 5. Set up timing to interface with off-chip memory or peripherals. Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition 16.2. 16.3. Port Selection and Configuration The External Memory Interface can appear on Ports 3, 2, 1, and 0 (C8051F04x devices) or on Ports 7, 6, 5, and 4 (C8051F040/2/4/6 devices only), depending on the state of the PRTSEL bit (EMI0CF.5). If the lower Ports are selected, the EMIFLE bit (XBR2.1) must be set to a ‘1’ so that the Crossbar will skip over P0.7 (/WR), P0.6 (/RD), and, if multiplexed mode is selected, P0.5 (ALE). For more information about the configuring the Crossbar, see Section “17.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 204. The External Memory Interface claims the associated Port pins for memory operations ONLY during the execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port pins reverts to the Port latches or to the Crossbar (on Ports 3, 2, 1, and 0). See Section “17. Port Input/ Output” on page 203 for more information about the Crossbar and Port operation and configuration. The Port latches should be explicitly configured as push-pull to ‘park’ the External Memory Interface pins in a dormant state, most commonly by setting them to a logic 1. During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the drivers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases, the output modes of all EMIF pins should be configured for push-pull mode. See Section “17.1.2. Configuring the Output Modes of the Port Pins” on page 206. 188 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 16.1. EMI0CN: External Memory Interface Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value PGSEL7 PGSEL6 PGSEL5 PGSEL4 PGSEL3 PGSEL2 PGSEL1 PGSEL0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-0: Bit0 SFR Address: 0xA2 SFR Page: 0 PGSEL[7:0]: XRAM Page Select Bits. The XRAM Page Select Bits provide the high byte of the 16-bit external data memory address when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. 0x00: 0x0000 to 0x00FF 0x01: 0x0100 to 0x01FF ... 0xFE: 0xFE00 to 0xFEFF 0xFF: 0xFF00 to 0xFFFF Rev. 1.6 189 C8051F040/1/2/3/4/5/6/7 SFR Definition 16.2. EMI0CF: External Memory Configuration R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - - PRTSEL EMD2 EMD1 EMD0 EALE1 EALE0 00000011 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-6: Bit5: Bit4: Bits3-2: Bits1-0: 190 Bit0 SFR Address: 0xA3 SFR Page: 0 Unused. Read = 00b. Write = don’t care. PRTSEL: EMIF Port Select. 0: EMIF active on P0-P3. 1: EMIF active on P4-P7. EMD2: EMIF Multiplex Mode Select. 0: EMIF operates in multiplexed address/data mode. 1: EMIF operates in non-multiplexed mode (separate address and data pins). EMD1-0: EMIF Operating Mode Select. These bits control the operating mode of the External Memory Interface. 00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to onchip memory space. 01: Split Mode without Bank Select: Accesses below the 4k boundary are directed on-chip. Accesses above the 4k boundary are directed off-chip. 8-bit off-chip MOVX operations use the current contents of the Address High port latches to resolve upper address byte. Note that in order to access off-chip space, EMI0CN must be set to a page that is not contained in the on-chip address space. 10: Split Mode with Bank Select: Accesses below the 4k boundary are directed on-chip. Accesses above the 4k boundary are directed off-chip. 8-bit off-chip MOVX operations use the contents of EMI0CN to determine the high-byte of the address. 11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the CPU. EALE1-0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 1). 00: ALE high and ALE low pulse width = 1 SYSCLK cycle. 01: ALE high and ALE low pulse width = 2 SYSCLK cycles. 10: ALE high and ALE low pulse width = 3 SYSCLK cycles. 11: ALE high and ALE low pulse width = 4 SYSCLK cycles. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16.4. Multiplexed and Non-multiplexed Selection The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode, depending on the state of the EMD2 (EMI0CF.4) bit. 16.4.1. Multiplexed Configuration In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins: AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in Figure 16.1. In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are presented to AD[7:0]. During this phase, the address latch is configured such that the ‘Q’ outputs reflect the states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data Bus controls the state of the AD[7:0] port at the time /RD or /WR is asserted. See Section “16.6.2. Multiplexed Mode” on page 199 for more information. Figure 16.1. Multiplexed Configuration Example Rev. 1.6 191 C8051F040/1/2/3/4/5/6/7 16.4.2. Non-multiplexed Configuration In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Nonmultiplexed Configuration is shown in Figure 16.2. See Section “16.6.1. Non-multiplexed Mode” on page 196 for more information about Non-multiplexed operation. Figure 16.2. Non-multiplexed Configuration Example 192 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16.5. Memory Mode Selection The external data memory space can be configured in one of four modes, shown in Figure 16.3, based on the EMIF Mode bits in the EMI0CF register (SFR Definition 16.2). These modes are summarized below. More information about the different modes can be found in Section “16.6. Timing” on page 194. 16.5.1. Internal XRAM Only When EMI0CF.[3:2] are set to ‘00’, all MOVX instructions will target the internal XRAM space on the device. Memory accesses to addresses beyond the populated space will wrap on 4k boundaries. As an example, the addresses 0x1000 and 0x2000 both evaluate to address 0x0000 in on-chip XRAM space. • • 8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address and R0 or R1 to determine the low-byte of the effective address. 16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address. 16.5.2. Split Mode without Bank Select When EMI0CF.[3:2] are set to ‘01’, the XRAM memory map is split into two areas, on-chip space and offchip space. • • • • Effective addresses below the 4k boundary will access on-chip XRAM space. Effective addresses above the 4k boundary will access off-chip space. 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is onchip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate the upper address bits at will by setting the Port state directly via the port latches. This behavior is in contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus A[7:0] are driven, determined by R0 or R1. 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is onchip or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. Figure 16.3. EMIF Operating Modes Rev. 1.6 193 C8051F040/1/2/3/4/5/6/7 16.5.3. Split Mode with Bank Select When EMI0CF.[3:2] are set to ‘10’, the XRAM memory map is split into two areas, on-chip space and offchip space. • • • • Effective addresses below the 4k boundary will access on-chip XRAM space. Effective addresses above the 4k boundary will access off-chip space. 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is onchip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the lower 8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus A[15:0] are driven in “Bank Select” mode. 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is onchip or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. 16.5.4. External Only When EMI0CF[3:2] are set to ‘11’, all MOVX operations are directed to off-chip space. On-chip XRAM is not visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the 4k boundary. • • 8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven (identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower 8-bits of the effective address A[7:0] are determined by the contents of R0 or R1. 16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. 16.6. Timing The timing parameters of the External Memory Interface can be configured to enable connection to devices having different setup and hold time requirements. The Address Setup time, Address Hold time, / RD and /WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in units of SYSCLK periods through EMI0TC, shown in SFR Definition 16.3, and EMI0CF[1:0]. The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for /RD or /WR pulse + 4 SYSCLKs). For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYSCLK cycles. Therefore, the minimum execution time of an off-chip XRAM operation in multiplexed mode is 7 SYSCLK cycles (2 SYSCLKs for /ALE, 1 for /RD or /WR + 4 SYSCLKs). The programmable setup and hold times default to the maximum delay settings after a reset. Table 16.1 lists the AC parameters for the External Memory Interface, and Figure 16.4 through Figure 16.9 show the timing diagrams for the different External Memory Interface modes and MOVX operations. 194 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 16.3. EMI0TC: External Memory Timing Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value EAS1 EAS0 ERW3 EWR2 EWR1 EWR0 EAH1 EAH0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-6: Bits5-2: Bits1-0: Bit0 SFR Address: 0xA1 SFR Page: 0 EAS1-0: EMIF Address Setup Time Bits. 00: Address setup time = 0 SYSCLK cycles. 01: Address setup time = 1 SYSCLK cycle. 10: Address setup time = 2 SYSCLK cycles. 11: Address setup time = 3 SYSCLK cycles. EWR3-0: EMIF /WR and /RD Pulse-Width Control Bits. 0000: /WR and /RD pulse width = 1 SYSCLK cycle. 0001: /WR and /RD pulse width = 2 SYSCLK cycles. 0010: /WR and /RD pulse width = 3 SYSCLK cycles. 0011: /WR and /RD pulse width = 4 SYSCLK cycles. 0100: /WR and /RD pulse width = 5 SYSCLK cycles. 0101: /WR and /RD pulse width = 6 SYSCLK cycles. 0110: /WR and /RD pulse width = 7 SYSCLK cycles. 0111: /WR and /RD pulse width = 8 SYSCLK cycles. 1000: /WR and /RD pulse width = 9 SYSCLK cycles. 1001: /WR and /RD pulse width = 10 SYSCLK cycles. 1010: /WR and /RD pulse width = 11 SYSCLK cycles. 1011: /WR and /RD pulse width = 12 SYSCLK cycles. 1100: /WR and /RD pulse width = 13 SYSCLK cycles. 1101: /WR and /RD pulse width = 14 SYSCLK cycles. 1110: /WR and /RD pulse width = 15 SYSCLK cycles. 1111: /WR and /RD pulse width = 16 SYSCLK cycles. EAH1-0: EMIF Address Hold Time Bits. 00: Address hold time = 0 SYSCLK cycles. 01: Address hold time = 1 SYSCLK cycle. 10: Address hold time = 2 SYSCLK cycles. 11: Address hold time = 3 SYSCLK cycles. Rev. 1.6 195 C8051F040/1/2/3/4/5/6/7 16.6.1. Non-multiplexed Mode 16.6.1.1.16-bit MOVX: EMI0CF[4:2] = ‘101’, ‘110’, or ‘111’. Figure 16.4. Non-multiplexed 16-bit MOVX Timing 196 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16.6.1.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘101’ or ‘111’. Figure 16.5. Non-multiplexed 8-bit MOVX without Bank Select Timing Rev. 1.6 197 C8051F040/1/2/3/4/5/6/7 16.6.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘110’. Figure 16.6. Non-multiplexed 8-bit MOVX with Bank Select Timing 198 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16.6.2. Multiplexed Mode 16.6.2.1.16-bit MOVX: EMI0CF[4:2] = ‘001’, ‘010’, or ‘011’. Figure 16.7. Multiplexed 16-bit MOVX Timing Rev. 1.6 199 C8051F040/1/2/3/4/5/6/7 16.6.2.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘001’ or ‘011’. Figure 16.8. Multiplexed 8-bit MOVX without Bank Select Timing 200 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 16.6.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘010’. Figure 16.9. Multiplexed 8-bit MOVX with Bank Select Timing Rev. 1.6 201 C8051F040/1/2/3/4/5/6/7 Table 16.1. AC Parameters for External Memory Interface Parameter Description Min Max Units TSYSCLK System Clock Period 40 — ns TACS Address/Control Setup Time 0 3 x TSYSCLK ns TACW Address/Control Pulse Width 1 x TSYSCLK 16 x TSYSCLK ns TACH Address/Control Hold Time 0 3 x TSYSCLK ns TALEH Address Latch Enable High Time 1 x TSYSCLK 4 x TSYSCLK ns TALEL Address Latch Enable Low Time 1 x TSYSCLK 4 x TSYSCLK ns TWDS Write Data Setup Time 1 x TSYSCLK 19 x TSYSCLK ns TWDH Write Data Hold Time 0 3 x TSYSCLK ns TRDS Read Data Setup Time 20 — ns TRDH Read Data Hold Time 0 — ns 202 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 17. Port Input/Output The C8051F04x family of devices are fully integrated mixed-signal System on a Chip MCUs with 64 digital I/O pins (C8051F040/2/4/6) or 32 digital I/O pins (C8051F041/3/5/7), organized as 8-bit Ports. All ports are both bit- and byte-addressable through their corresponding Port Data registers. All Port pins are 5 V-tolerant, and all support configurable Open-Drain or Push-Pull output modes and weak pullups. A block diagram of the Port I/O cell is shown in Figure 17.1. Complete Electrical Specifications for the Port I/O pins are given in Table 17.1. Figure 17.1. Port I/O Cell Block Diagram Table 17.1. Port I/O DC Electrical Characteristics VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units VDD – 0.7 VDD – 0.1 — — — V — — — VDD – 0.8 — — — — — 1.0 0.6 0.1 — V Input High Voltage (VIH) 0.7 x VDD — — Input Low Voltage (VIL) — — 0.3 x VDD — — — — — 10 — ±1 — μA — 5 — pF Output High Voltage (VOH) IOH = –3 mA, Port I/O Push-Pull IOH = –10 μA, Port I/O Push-Pull IOH = –10 mA, Port I/O Push-Pull Output Low Voltage (VOL) IOL = 8.5 mA IOL = 10 μA IOL = 25 mA Input Leakage Current DGND < Port Pin < VDD, Pin Tri-state Weak Pullup Off Weak Pullup On Input Capacitance Rev. 1.6 203 C8051F040/1/2/3/4/5/6/7 The C8051F04x family of devices have a wide array of digital resources which are available through the four lower I/O Ports: P0, P1, P2, and P3. Each of the pins on P0, P1, P2, and P3, can be defined as a General-Purpose I/O (GPIO) pin or can be controlled by a digital peripheral or function (like UART0 or /INT1 for example), as shown in Figure 17.2. The system designer controls which digital functions are assigned pins, limited only by the number of pins available. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. The state of a Port I/O pin can always be read from its associated Data register regardless of whether that pin has been assigned to a digital peripheral or behaves as GPIO. The Port pins on Ports 1, 2, and 3 can be used as Analog Inputs to ADC2 (C8051F040/1/2/3 only), Analog Voltage Comparators, and ADC0, respectively. Figure 17.2. Port I/O Functional Block Diagram An External Memory Interface, which is active during the execution of an off-chip MOVX instruction, can be active on either the lower Ports or the upper Ports. See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. 17.1. Ports 0 through 3 and the Priority Crossbar Decoder The Priority Crossbar Decoder, or “Crossbar”, allocates and assigns Port pins on Port 0 through Port 3 to the digital peripherals (UARTs, SMBus, PCA, Timers, etc.) on the device using a priority order. The Port pins are allocated in order starting with P0.0 and continue through P3.7, if necessary. The digital peripherals are assigned Port pins in a priority order which is listed in Figure 17.3, with UART0 having the highest priority and CNVSTR2 having the lowest priority. 204 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 P0 PIN I/O 0 5 6 7 0 1 2 3 P3 4 5 6 7 0 1 2 3 4 5 6 7 z z SPI0EN: XBR0.1 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z PCA0ME: XBR0.[5:3] AIN1 Inputs/Non-muxed Addr H z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 ECI0E: XBR0.6 z z z z z z z z z z z z z z z z z AD0/D0 CP0E: XBR0.7 CP1E: XBR1.0 CP2E: XBR3.3 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 Muxed Addr H/Non-muxed Addr L INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T3E: XBR3.0 T3EXE: XBR3.1 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR3.2 AD7/D7 AD6/D6 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z UART1EN: XBR2.2 A15m/A7 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z A14m/A6 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z A13m/A5 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z A12m/A4 z z z z z z z z z z z z z z z z z SMB0EN: XBR0.0 A11m/A3 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z CEX5 NSS is not assigned to a port pin when the SPI is placed in 3-wire mode z z z z z z z z z A10m/A2 z z z z z z z z z A9m/A1 z z z z z z z A8m/A0 z z z z z z z z z z z z z z z z z z AIN1.7/A15 z AIN1.6/A14 z z CP0 z CP1 z CP2 z T0 z /INT0 z T1 z /INT1 z T2 z T2EX z T3 z T3EX z T4 z T4EX z /SYSCLK z CNVSTR0 z CNVSTR2 z Crossbar Register Bits UART0EN: XBR0.2 CEX4 ECI P2 4 AIN1.5/A13 CEX3 3 AIN1.4/A12 CEX2 2 AIN1.3/A11 CEX1 1 AIN1.2/A10 CEX0 0 AIN1.1/A9 RX1 7 AIN1.0/A8 TX1 6 /WR SCL 5 /RD z MOSI SDA P1 4 z MISO NSS 3 z RX0 SCK 2 ALE TX0 1 Muxed Data/Non-muxed Data Figure 17.3. Priority Crossbar Decode Table (EMIFLE = 0; P1MDIN = 0xFF) 17.1.1. Crossbar Pin Assignment and Allocation The Crossbar assigns Port pins to a peripheral if the corresponding enable bits of the peripheral are set to a logic 1 in the Crossbar configuration registers XBR0, XBR1, XBR2, and XBR3, shown in SFR Definition 17.1, SFR Definition 17.2, SFR Definition 17.3, and SFR Definition 17.4. For example, if the UART0EN bit (XBR0.2) is set to a logic 1, the TX0 and RX0 pins will be mapped to P0.0 and P0.1 respectively. Because UART0 has the highest priority, its pins will always be mapped to P0.0 and P0.1 when UART0EN is set to a logic 1. If a digital peripheral’s enable bits are not set to a logic 1, then its ports are not accessible at the Port pins of the device. Also note that the Crossbar assigns pins to all associated functions when a serial communication peripheral is selected (i.e. SMBus, SPI, UART). It would be impossible, for example, to assign TX0 to a Port pin without assigning RX0 as well. Each combination of enabled peripherals results in a unique device pinout. All Port pins on Ports 0 through 3 that are not allocated by the Crossbar can be accessed as General-Purpose I/O (GPIO) pins by reading and writing the associated Port Data registers (See SFR Definition 17.5, Rev. 1.6 205 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.7, SFR Definition 17.10, and SFR Definition 17.13), a set of SFRs which are both byteand bit-addressable. The output states of Port pins that are allocated by the Crossbar are controlled by the digital peripheral that is mapped to those pins. Writes to the Port Data registers (or associated Port bits) will have no effect on the states of these pins. A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regardless of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC, CLR, SET, and the bitwise MOV operation). During the read cycle of the read-modify-write instruction, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read. Because the Crossbar registers affect the pinout of the peripherals of the device, they are typically configured in the initialization code of the system before the peripherals themselves are configured. Once configured, the Crossbar registers are typically left alone. Once the Crossbar registers have been properly configured, the Crossbar is enabled by setting XBARE (XBR2.4) to a logic 1. Until XBARE is set to a logic 1, the output drivers on Ports 0 through 3 are explicitly disabled in order to prevent possible contention on the Port pins while the Crossbar registers and other registers which can affect the device pinout are being written. The output drivers on Crossbar-assigned input signals (like RX0, for example) are explicitly disabled; thus the values of the Port Data registers and the PnMDOUT registers have no effect on the states of these pins. 17.1.2. Configuring the Output Modes of the Port Pins The output drivers on Ports 0 through 3 remain disabled until the Crossbar is enabled by setting XBARE (XBR2.4) to a logic 1. The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and writing a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent contention between devices in systems where the Port pin participates in a shared interconnection in which multiple outputs are connected to the same physical wire (like the SDA signal on an SMBus connection). The output modes of the Port pins on Ports 0 through 3 are determined by the bits in the associated PnMDOUT registers (See SFR Definition 17.6, SFR Definition 17.9, SFR Definition 17.12, and SFR Definition 17.15). For example, a logic 1 in P3MDOUT.7 will configure the output mode of P3.7 to Push-Pull; a logic 0 in P3MDOUT.7 will configure the output mode of P3.7 to Open-Drain. All Port pins default to OpenDrain output. The PnMDOUT registers control the output modes of the port pins regardless of whether the Crossbar has allocated the Port pin for a digital peripheral or not. The exceptions to this rule are: the Port pins connected to SDA, SCL, RX0 (if UART0 is in Mode 0), and RX1 (if UART1 is in Mode 0) are always configured as Open-Drain outputs, regardless of the settings of the associated bits in the PnMDOUT registers. 17.1.3. Configuring Port Pins as Digital Inputs A Port pin is configured as a digital input by setting its output mode to “Open-Drain” in the PnMDOUT register and writing a logic 1 to the associated bit in the Port Data register. For example, P3.7 is configured as 206 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 a digital input by setting P3MDOUT.7 to a logic 0, which selects open-drain output mode, and P3.7 to a logic 1, which disables the low-side output driver. If the Port pin has been assigned to a digital peripheral by the Crossbar and that pin functions as an input (for example RX0, the UART0 receive pin), then the output drivers on that pin are automatically disabled. 17.1.4. Weak Pullups By default, each Port pin has an internal weak pullup device enabled which provides a resistive connection (about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device. The weak pullup device can also be explicitly disabled on Ports 1, 2, and 3 pin by configuring the pin as an Analog Input, as described below. 17.1.5. Configuring Port 1, 2, and 3 Pins as Analog Inputs The pins on Port 1 can serve as analog inputs to the ADC2 analog MUX (C8051F040/1/2/3 only), the pins on Port 2 can serve as analog inputs to the Comparators, and the pins on Port 3 can serve as inputs to ADC0. A Port pin is configured as an Analog Input by writing a logic 0 to the associated bit in the PnMDIN registers. All Port pins default to a Digital Input mode. Configuring a Port pin as an analog input: 1. Disables the digital input path from the pin. This prevents additional power supply current from being drawn when the voltage at the pin is near VDD / 2. A read of the Port Data bit will return a logic 0 regardless of the voltage at the Port pin. 2. Disables the weak pullup device on the pin. 3. Causes the Crossbar to “skip over” the pin when allocating Port pins for digital peripherals, except for P2.0-P2.1. Note that the output drivers on a pin configured as an Analog Input are not explicitly disabled. Therefore, the associated PnMDOUT bits of pins configured as Analog Inputs should explicitly be set to logic 0 (Open-Drain output mode), and the associated Port Data bits should be set to logic 1 (high-impedance). Also note that it is not required to configure a Port pin as an Analog Input in order to use it as an input to the ADC’s or Comparators; however, it is strongly recommended. See the analog peripheral’s corresponding section in this datasheet for further information. Rev. 1.6 207 C8051F040/1/2/3/4/5/6/7 17.1.6. External Memory Interface Pin Assignments If the External Memory Interface (EMIF) is enabled on the Low ports (Ports 0 through 3), EMIFLE (XBR2.5) should be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and, if the External Memory Interface is in Multiplexed mode, P0.5 (ALE). Figure 17.4 shows an example Crossbar Decode Table with EMIFLE=1 and the EMIF in Multiplexed mode. Figure 17.5 shows an example Crossbar Decode Table with EMIFLE=1 and the EMIF in Non-multiplexed mode. If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the External Memory Interface will control the output states (logic 1 or logic 0) of the affected Port pins during the execution phase of the MOVX instruction, regardless of the settings of the Crossbar registers or the Port Data registers. The output configuration (push-pull or open-drain) of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output drivers on the Data Bus. In most cases, GPIO pins used in EMIF operations (especially the /WR and /RD lines) should be configured as push-pull and ‘parked’ at a logic 1 state. See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. P0 PIN I/O 0 5 6 7 0 1 2 3 P3 4 5 6 7 0 1 2 3 4 5 6 7 Crossbar Register Bits UART0EN: XBR0.2 z z SPI0EN: XBR0.1 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z UART1EN: XBR2.2 AIN1 Inputs/Non-muxed Addr H z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 AD6/D6 AD7/D7 PCA0ME: XBR0.[5:3] z z z z z z z z z z z z z z z z z z z z AD0/D0 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z A15m/A7 z z z z z z z z z z z z z z z z z SMB0EN: XBR0.0 A14m/A6 z z z z z z z z z z z z z z z z z /WR z z z z z z z z z z z z z z z z z /RD z z z z z z z z z z z z z z z z z ALE z CP0 z CP1 z CP2 z T0 z /INT0 z T1 z /INT1 z T2 z T2EX z T3 z T3EX z T4 z T4EX z /SYSCLK z CNVSTR0 z CNVSTR2 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z CEX5 z z z z z z z z z A13m/A5 z z z z z z z NSS is not assigned to a port pin when the SPI is placed in 3-wire mode A12m/A4 z z z z z z z z z A11m/A3 z z z z z z z z z z z z z z z z z z A10m/A2 z A9m/A1 z CEX4 ECI P2 4 A8m/A0 CEX3 3 AIN1.7/A15 CEX2 2 AIN1.6/A14 CEX1 1 AIN1.5/A13 CEX0 0 AIN1.4/A12 RX1 7 AIN1.3/A11 TX1 6 AIN1.2/A10 SCL 5 AIN1.1/A9 z MOSI SDA P1 4 z MISO NSS 3 z RX0 SCK 2 AIN1.0/A8 TX0 1 ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 CP2E: XBR3.3 Muxed Addr H/Non-muxed Addr L T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T3E: XBR3.0 T3EXE: XBR3.1 Muxed Data/Non-muxed Data Figure 17.4. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xFF) 208 Rev. 1.6 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR3.2 C8051F040/1/2/3/4/5/6/7 P0 PIN I/O 0 5 6 7 0 1 2 3 P3 4 5 6 7 0 1 2 3 4 5 6 7 z z SPI0EN: XBR0.1 z AIN1 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L SMB0EN: XBR0.0 UART1EN: XBR2.2 PCA0ME: XBR0.[5:3] ECI0E: XBR0.6 CP0E: XBR0.7 CP1E: XBR1.0 CP2E: XBR3.3 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 z z z z z z z z z z z z z z z z z z z z z z AD5/D5 AD6/D6 AD7/D7 T2EXE: XBR1.6 z z z z z z z z AD4/D4 AD2/D2 AD1/D1 z z z z z z z z z z z z z z z z z z AD0/D0 z z z z z z z z z z z z z z z z z A15m/A7 z z z z z z z z z z z z z z z z z A14m/A6 z z z z z z z z z z z z z z z z z ALE z z z z z z z z z z z z z z z z z A13m/A5 CEX5 A12m/A4 z A11m/A3 NSS is not assigned to a port pin when the SPI is placed in 3-wire mode z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z AD3/D3 z z z z z z z z z A10m/A2 z z z z z z z A9m/A1 z z z z z z z z z z z z z z z z z z A8m/A0 z AIN1.7/A15 z z CP0 z CP1 z CP2 z T0 z /INT0 z T1 z /INT1 z T2 z T2EX z T3 z T3EX z T4 z T4EX z /SYSCLK z CNVSTR0 z CNVSTR2 z Crossbar Register Bits UART0EN: XBR0.2 CEX4 ECI P2 4 AIN1.6/A14 CEX3 3 AIN1.5/A13 CEX2 2 AIN1.4/A12 CEX1 1 AIN1.3/A11 CEX0 0 AIN1.2/A10 RX1 7 AIN1.1/A9 TX1 6 /WR SCL 5 AIN1.0/A8 z MOSI SDA P1 4 z MISO NSS 3 z RX0 SCK 2 /RD TX0 1 T3E: XBR3.0 T3EXE: XBR3.1 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR3.2 Muxed Data/Non-muxed Data Figure 17.5. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Non-multiplexed Mode; P1MDIN = 0xFF) Rev. 1.6 209 C8051F040/1/2/3/4/5/6/7 17.1.7. Crossbar Pin Assignment Example In this example (Figure 17.6), we configure the Crossbar to allocate Port pins for UART0, the SMBus, UART1, /INT0, and /INT1 (8 pins total). Additionally, we configure the External Memory Interface to operate in Multiplexed mode and to appear on the Low ports. Further, we configure P1.2, P1.3, and P1.4 for Analog Input mode so that the voltages at these pins can be measured by ADC2. The configuration steps are as follows: 1. XBR0, XBR1, and XBR2 are set such that UART0EN = 1, SMB0EN = 1, INT0E = 1, INT1E = 1, and EMIFLE = 1. Thus: XBR0 = 0x05, XBR1 = 0x14, and XBR2 = 0x02. 2. We configure the External Memory Interface to use Multiplexed mode and to appear on the Low ports. PRTSEL = 0, EMD2 = 0. 3. We configure the desired Port 1 pins to Analog Input mode by setting P1MDIN to 0xE3 (P1.4, P1.3, and P1.2 are Analog Inputs, so their associated P1MDIN bits are set to logic 0). 4. We enable the Crossbar by setting XBARE = 1: XBR2 = 0x42. - UART0 has the highest priority, so P0.0 is assigned to TX0, and P0.1 is assigned to RX0. - The SMBus is next in priority order, so P0.2 is assigned to SDA, and P0.3 is assigned to SCL. - UART1 is next in priority order, so P0.4 is assigned to TX1. Because the External Memory Interface is selected on the lower Ports, EMIFLE = 1, which causes the Crossbar to skip P0.6 (/RD) and P0.7 (/WR). Because the External Memory Interface is configured in Multiplexed mode, the Crossbar will also skip P0.5 (ALE). RX1 is assigned to the next nonskipped pin, which in this case is P1.0. - /INT0 is next in priority order, so it is assigned to P1.1. - P1MDIN is set to 0xE3, which configures P1.2, P1.3, and P1.4 as Analog Inputs, causing the Crossbar to skip these pins. - /INT1 is next in priority order, so it is assigned to the next non-skipped pin, which is P1.5. - The External Memory Interface will drive Ports 2 and 3 (denoted by red dots in Figure 17.6) during the execution of an off-chip MOVX instruction. 5. We set the UART0 TX pin (TX0, P0.0) and UART1 TX pin (TX1, P0.4) outputs to Push-Pull by setting P0MDOUT = 0x11. 6. We configure all EMIF-controlled pins to push-pull output mode by setting P0MDOUT |= 0xE0; P2MDOUT = 0xFF; P3MDOUT = 0xFF. 7. We explicitly disable the output drivers on the 3 Analog Input pins by setting P1MDOUT = 0x00 (configure outputs to Open-Drain) and P1 = 0xFF (a logic 1 selects the high-impedance state). 210 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 P0 PIN I/O 0 5 6 7 0 1 2 3 P3 4 5 6 7 0 1 2 3 4 5 6 7 z z SPI0EN: XBR0.1 z AIN1 Inputs/Non-muxed Addr H z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z AD1/D1 AD2/D2 AD3/D3 AD4/D4 AD5/D5 AD6/D6 AD7/D7 UART1EN: XBR2.2 AD0/D0 z z z z z z z z z z z z z z z z z z z z z z z z A15m/A7 z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z A14m/A6 z z z z z z z z z z z z z z z z z /WR z z z z z z z z z z z z z z z z z /RD z z z z z z z z z z z z z z z z z ALE z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z SMB0EN: XBR0.0 z z z z z z z z z z z z z z z z z z z z z z z z z z A13m/A5 z CEX5 z z z z z z z z z A12m/A4 z z z z z z z z z z z z z z z z A11m/A3 z z z z z z z z z z z z z z z z z z A10m/A2 z A9m/A1 z z CP0 z CP1 z CP2 z T0 z /INT0 z T1 z /INT1 z T2 z T2EX z T3 z T3EX z T4 z T4EX z /SYSCLK z CNVSTR0 z CNVSTR2 z Crossbar Register Bits UART0EN: XBR0.2 CEX4 ECI P2 4 A8m/A0 CEX3 3 AIN1.7/A15 CEX2 2 AIN1.6/A14 CEX1 1 AIN1.5/A13 CEX0 0 AIN1.4/A12 RX1 7 AIN1.3/A11 TX1 6 AIN1.1/A9 SCL 5 AIN1.2/A10 z MOSI SDA P1 4 z MISO NSS 3 z RX0 SCK 2 AIN1.0/A8 TX0 1 PCA0ME: XBR0.[5:3] ECI0E: XBR0.6 Muxed Addr H/Non-muxed Addr L CP0E: XBR0.7 CP1E: XBR1.0 CP2E: XBR3.2 T0E: XBR1.1 INT0E: XBR1.2 T1E: XBR1.3 INT1E: XBR1.4 T2E: XBR1.5 T2EXE: XBR1.6 T3E: XBR3.0 T3EXE: XBR3.1 T4E: XBR2.3 T4EXE: XBR2.4 SYSCKE: XBR1.7 CNVSTE0: XBR2.0 CNVSTE2: XBR3.2 Muxed Data/Non-muxed Data Figure 17.6. Crossbar Example: (EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xE3; XBR0 = 0x05; XBR1 = 0x14; XBR2 = 0x42) Rev. 1.6 211 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.1. XBR0: Port I/O Crossbar Register 0 R/W R/W CP0E ECI0E Bit7 Bit6 Bit7: Bit6: Bits5-3: Bit2: Bit1: Bit0: 212 R/W R/W R/W PCA0ME Bit5 Bit4 R/W R/W UART0EN SPI0EN Bit3 Bit2 Bit1 R/W Reset Value SMB0EN 00000000 Bit0 SFR Address: 0xE1 SFR Page: F CP0E: Comparator 0 Output Enable Bit. 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. ECI0E: PCA0 External Counter Input Enable Bit. 0: PCA0 External Counter Input unavailable at Port pin. 1: PCA0 External Counter Input (ECI0) routed to Port pin. PCA0ME: PCA0 Module I/O Enable Bits. 000: All PCA0 I/O unavailable at port pins. 001: CEX0 routed to port pin. 010: CEX0, CEX1 routed to 2 port pins. 011: CEX0, CEX1, and CEX2 routed to 3 port pins. 100: CEX0, CEX1, CEX2, and CEX3 routed to 4 port pins. 101: CEX0, CEX1, CEX2, CEX3, and CEX4 routed to 5 port pins. 110: CEX0, CEX1, CEX2, CEX3, CEX4, and CEX5 routed to 6 port pins. UART0EN: UART0 I/O Enable Bit. 0: UART0 I/O unavailable at Port pins. 1: UART0 TX routed to P0.0, and RX routed to P0.1. SPI0EN: SPI0 Bus I/O Enable Bit. 0: SPI0 I/O unavailable at Port pins. 1: SPI0 SCK, MISO, MOSI, and NSS routed to 4 Port pins. Note that the NSS signal is not assigned to a port pin if the SPI is in 3-wire mode. See Section “20. Enhanced Serial Peripheral Interface (SPI0)” on page 255 for more information. SMB0EN: SMBus0 Bus I/O Enable Bit. 0: SMBus0 I/O unavailable at Port pins. 1: SMBus0 SDA and SCL routed to 2 Port pins. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.2. XBR1: Port I/O Crossbar Register 1 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value SYSCKE T2EXE T2E INT1E T1E INT0E T0E CP1E 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit0 SFR Address: 0xE2 SFR Page: F SYSCKE: /SYSCLK Output Enable Bit. 0: /SYSCLK unavailable at Port pin. 1: /SYSCLK routed to Port pin. T2EXE: T2EX Input Enable Bit. 0: T2EX unavailable at Port pin. 1: T2EX routed to Port pin. T2E: T2 Input Enable Bit. 0: T2 unavailable at Port pin. 1: T2 routed to Port pin. INT1E: /INT1 Input Enable Bit. 0: /INT1 unavailable at Port pin. 1: /INT1 routed to Port pin. T1E: T1 Input Enable Bit. 0: T1 unavailable at Port pin. 1: T1 routed to Port pin. INT0E: /INT0 Input Enable Bit. 0: /INT0 unavailable at Port pin. 1: /INT0 routed to Port pin. T0E: T0 Input Enable Bit. 0: T0 unavailable at Port pin. 1: T0 routed to Port pin. CP1E: CP1 Output Enable Bit. 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin. Rev. 1.6 213 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.3. XBR2: Port I/O Crossbar Register 2 R/W R/W WEAKPUD XBARE Bit7 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 214 Bit6 R/W R/W R/W R/W R/W — T4EXE T4E UART1E EMIFLE Bit5 Bit4 Bit3 Bit2 Bit1 R/W Reset Value CNVST0E 00000000 Bit0 SFR Address: 0xE3 SFR Page: F WEAKPUD: Weak PullUp Disable Bit. 0: Weak pullups globally enabled. 1: Weak pullups globally disabled. XBARE: Crossbar Enable Bit. 0: Crossbar disabled. All pins on Ports 0, 1, 2, and 3, are forced to Input mode. 1: Crossbar enabled. UNUSED. Read = 0, Write = don't care. T4EXE: T4EX Input Enable Bit. 0: T4EX unavailable at Port pin. 1: T4EX routed to Port pin. T4E: T4 Input Enable Bit. 0: T4 unavailable at Port pin. 1: T4 routed to Port pin. UART1E: UART1 I/O Enable Bit. 0: UART1 I/O unavailable at Port pins. 1: UART1 TX and RX routed to 2 Port pins. EMIFLE: External Memory Interface Low-Port Enable Bit. 0: P0.7, P0.6, and P0.5 functions are determined by the Crossbar or the Port latches. 1: If EMI0CF.4 = ‘0’ (External Memory Interface is in Multiplexed mode) P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) are ‘skipped’ by the Crossbar and their output states are determined by the Port latches and the External Memory Interface. 1: If EMI0CF.4 = ‘1’ (External Memory Interface is in Non-multiplexed mode) P0.7 (/WR) and P0.6 (/RD) are ‘skipped’ by the Crossbar and their output states are determined by the Port latches and the External Memory Interface. CNVST0E: ADC0 External Convert Start Input Enable Bit. 0: CNVST0 for ADC0 unavailable at Port pin. 1: CNVST0 for ADC0 routed to Port pin. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.4. XBR3: Port I/O Crossbar Register 3 R/W R R R R/W R/W R/W R/W Reset Value CTXOUT — — — CP2E CNVST2E T3EXE T3E 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6-4: Bit3: Bit2: Bit1: Bit0: Bit0 SFR Address: 0xE4 SFR Page: F CTXOUT: CAN Transmit Pin (CTX) Output Mode. 0: CTX pin output mode is configured as open-drain. 1: CTX pin output mode is configured as push-pull. Reserved CP2E: CP2 Output Enable Bit. 0: CP2 unavailable at Port pin. 1: CP2 routed to Port pin. CNVST2E: ADC2 External Convert Start Input Enable Bit (C8051F040/1/2/3 only). 0: CNVST2 for ADC2 unavailable at Port pin. 1: CNVST2 for ADC2 routed to Port pin. T3EXE: T3EX Input Enable Bit. 0: T3EX unavailable at Port pin. 1: T3EX routed to Port pin. T3E: T3 Input Enable Bit. 0: T3 unavailable at Port pin. 1: T3 routed to Port pin. SFR Definition 17.5. P0: Port0 Data 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 Bits7-0: Bit Addressable SFR Address: 0x80 SFR Page: All Pages Bit0 P0.[7:0]: Port0 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, XBR2, and XBR3 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P0MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, XBR2, and XBR3 Register settings). 0: P0.n pin is logic low. 1: P0.n pin is logic high. Note: P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) can be driven by the External Data Memory Interface. See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information. See also SFR Definition 17.3 for information about configuring the Crossbar for External Memory accesses. Rev. 1.6 215 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.6. P0MDOUT: Port0 Output Mode 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: 0xA4 SFR Page: F Bits7-0: P0MDOUT.[7:0]: Port0 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins. SFR Definition 17.7. P1: Port1 Data 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 Bits7-0: Notes: 1. 2. 216 Bit Addressable SFR Address: 0x90 SFR Page: All Pages Bit0 P1.[7:0]: Port1 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, XBR2, and XBR3 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P1MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, XBR2, and XBR3 Register settings). 0: P1.n pin is logic low. 1: P1.n pin is logic high. P1.[7:0] can be configured as inputs to ADC1 as AIN1.[7:0], in which case they are ‘skipped’ by the Crossbar assignment process and their digital input paths are disabled, depending on P1MDIN (See SFR Definition 17.8). Note that in analog mode, the output mode of the pin is determined by the Port 1 latch and P1MDOUT (SFR Definition 17.9). See Section “7. 8-Bit ADC (ADC2, C8051F040/1/2/3 Only)” on page 91 for more information about ADC2. P1.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.8. P1MDIN: Port1 Input Mode 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 11111111 Bits7-0: Bit0 SFR Address: 0xAD SFR Page: F P1MDIN.[7:0]: Port 1 Input Mode Bits. 0: Port Pin is configured in Analog Input mode. The digital input path is disabled (a read from the Port bit will always return ‘0’). The weak pullup on the pin is disabled. 1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic level at the Pin. The state of the weak pullup is determined by the WEAKPUD bit (XBR2.7, see SFR Definition 17.3). SFR Definition 17.9. P1MDOUT: Port1 Output 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: 0xA5 SFR Page: F Bits7-0: P1MDOUT.[7:0]: Port1 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins. Rev. 1.6 217 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.10. P2: Port2 Data 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 Bit Addessable SFR Address: 0xA0 SFR Page: All Pages Bit0 Bits7-0: P2.[7:0]: Port2 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, XBR2, and XBR3 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P2MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, XBR2, and XBR3 Register settings). 0: P2.n pin is logic low. 1: P2.n pin is logic high. Note: P2.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed mode, or as Address[7:0] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. SFR Definition 17.11. P2MDIN: Port2 Input Mode 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 11111111 Bits7-0: Notes: 1. 2. 218 Bit0 SFR Address: 0xAE SFR Page: F P1MDIN.[7:0]: Port 2 Input Mode Bits. 0: Port Pin is configured in Analog Input mode. The digital input path is disabled (a read from the Port bit will always return ‘0’). The weak pullup on the pin is disabled. 1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic level at the Pin. The state of the weak pullup is determined by the WEAKPUD bit (XBR2.7, see SFR Definition 17.3). When P2.0 is configured to Analog Input mode, the crossbar does not skip over this pin, and the crossbar is allowed to allocate digital peripherals on this pin. When P2.1 is configured to Analog Input mode, the crossbar does not skip over this pin, and the crossbar is allowed to allocate digital peripherals on this pin. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.12. P2MDOUT: Port2 Output Mode 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: 0xA6 SFR Page: F Bits7-0: P2MDOUT.[7:0]: Port2 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins. SFR Definition 17.13. P3: Port3 Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xB0 SFR Page: All Pages Bit0 Bits7-0: P3.[7:0]: Port3 Output Latch Bits. (Write - Output appears on I/O pins per XBR0, XBR1, XBR2, and XBR3 Registers) 0: Logic Low Output. 1: Logic High Output (open if corresponding P3MDOUT.n bit = 0). (Read - Regardless of XBR0, XBR1, XBR2, and XBR3 Register settings). 0: P3.n pin is logic low. 1: P3.n pin is logic high. Note: P3.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed mode, or as D[7:0] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. Rev. 1.6 219 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.14. P3MDIN: Port3 Input Mode 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 11111111 Bits7-0: Bit0 SFR Address: 0xAF SFR Page: F P1MDIN.[7:0]: Port 3 Input Mode Bits. 0: Port Pin is configured in Analog Input mode. The digital input path is disabled (a read from the Port bit will always return ‘0’). The weak pullup on the pin is disabled. 1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic level at the Pin. The state of the weak pullup is determined by the WEAKPUD bit (XBR2.7, see SFR Definition 17.3). SFR Definition 17.15. P3MDOUT: Port3 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA7 SFR Page: F P2MDOUT.[7:0]: Port3 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. 17.2. Ports 4 through 7 On C8051F040/2/4/6 devices, all Port pins on Ports 4 through 7 can be accessed as General-Purpose I/O (GPIO) pins by reading and writing the associated Port Data registers (See SFR Definition 17.16, SFR Definition 17.18, SFR Definition 17.20, and SFR Definition 17.22 located on SFR Page F), a set of SFRs which are both bit and byte-addressable. A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regardless of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC, CLR, SET, and the bitwise MOV operation). During the read cycle of the read-modify-write instruction, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read. 220 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 17.2.1. Configuring Ports Which are Not Pinned Out Although P4, P5, P6, and P7 are not brought out to pins on the C8051F041/3/5/7 devices, the Port Data registers are still present and can be used by software. Because the digital input paths also remain active, it is recommended that these pins not be left in a ‘floating’ state in order to avoid unnecessary power dissipation arising from the inputs floating to non-valid logic levels. This condition can be prevented by any of the following: 1. Leave the weak pullup devices enabled by setting WEAKPUD (XBR2.7) to a logic 0. 2. Configure the output modes of P4, P5, P6, and P7 to “Push-Pull” by writing PnOUT = 0xFF. 3. Force the output states of P4, P5, P6, and P7 to logic 0 by writing zeros to the Port Data registers: P4 = 0x00, P5 = 0x00, P6= 0x00, and P7 = 0x00. 17.2.2. Configuring the Output Modes of the Port Pins The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent contention between devices in systems where the Port pin participates in a shared interconnection in which multiple outputs are connected to the same physical wire. The output modes of the Port pins on Ports 4 through 7 are determined by the bits in their respective PnMDOUT Output Mode Registers. Each bit in PnMDOUT controls the output mode of its corresponding port pin (see SFR Definition 17.17, SFR Definition 17.19, SFR Definition 17.21, and SFR Definition 17.23). For example, to place Port pin 4.3 in push-pull mode (digital output), set P4MDOUT.3 to logic 1. All port pins default to open-drain mode upon device reset. 17.2.3. Configuring Port Pins as Digital Inputs A Port pin is configured as a digital input by setting its output mode to "Open-Drain" in the PnMDOUT register and writing a logic 1 to the associated bit in the Port Data register. For example, P7.7 is configured as a digital input by setting P7MDOUT.7 to a logic 0, which selects open-drain output mode, and P3.7 to a logic 1, which disables the low-side output driver. 17.2.4. Weak Pullups By default, each Port pin has an internal weak pullup device enabled which provides a resistive connection (about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device. 17.2.5. External Memory Interface If the External Memory Interface (EMIF) is enabled on the High ports (Ports 4 through 7), EMIFLE (XBR2.5) should be set to a logic 0. If the External Memory Interface is enabled on the High ports and an off-chip MOVX operation occurs, the External Memory Interface will control the output states of the affected Port pins during the execution phase of the MOVX instruction, regardless of the settings of the Port Data registers. The output configuration of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output drivers on the Data Bus during the MOVX execution. See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. Rev. 1.6 221 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.16. P4: Port4 Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P4.7 P4.6 P4.5 P4.4 P4.3 P4.2 P4.1 P4.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bits7-0: Bit Addressable SFR Address: 0xC8 SFR Page: F Bit0 P4.[7:0]: Port4 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P4MDOUT.n bit = 0). See SFR Definition 17.17. Read - Returns states of I/O pins. 0: P4.n pin is logic low. 1: P4.n pin is logic high. Note: P4.7 (/WR), P4.6 (/RD), and P4.5 (ALE) can be driven by the External Data Memory Interface. See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information. SFR Definition 17.17. P4MDOUT: Port4 Output Mode 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 Bits7-0: 222 P4MDOUT.[7:0]: Port4 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Rev. 1.6 Bit0 SFR Address: 0x9C SFR Page: F C8051F040/1/2/3/4/5/6/7 SFR Definition 17.18. P5: Port5 Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P5.7 P5.6 P5.5 P5.4 P5.3 P5.2 P5.1 P5.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xD8 SFR Page: F Bit0 Bits7-0: P5.[7:0]: Port5 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P5MDOUT bit = 0). See SFR Definition 17.19. Read - Returns states of I/O pins. 0: P5.n pin is logic low. 1: P5.n pin is logic high. Note: P5.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. SFR Definition 17.19. P5MDOUT: Port5 Output Mode 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 Bits7-0: Bit0 SFR Address: 0x9D SFR Page: F P5MDOUT.[7:0]: Port5 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Rev. 1.6 223 C8051F040/1/2/3/4/5/6/7 SFR Definition 17.20. P6: Port6 Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P6.7 P6.6 P6.5 P6.4 P6.3 P6.2 P6.1 P6.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xE8 SFR Page: F Bit0 Bits7-0: P6.[7:0]: Port6 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P6MDOUT bit = 0). See SFR Definition 17.21. Read - Returns states of I/O pins. 0: P6.n pin is logic low. 1: P6.n pin is logic high. Note: P6.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed mode, or as Address[7:0] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. SFR Definition 17.21. P6MDOUT: Port6 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: 224 Bit6 Bit5 Bit4 Bit3 Bit2 P6MDOUT.[7:0]: Port6 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Rev. 1.6 Bit1 Bit0 SFR Address: 0x9E SFR Page: F C8051F040/1/2/3/4/5/6/7 SFR Definition 17.22. P7: Port7 Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P7.7 P7.6 P7.5 P7.4 P7.3 P7.2 P7.1 P7.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit Addressable SFR Address: 0xF8 SFR Page: F Bit0 Bits7-0: P7.[7:0]: Port7 Output Latch Bits. Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (Open-Drain if corresponding P7MDOUT bit = 0). See SFR Definition 17.23. Read - Returns states of I/O pins. 0: P7.n pin is logic low. 1: P7.n pin is logic high. Note: P7.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed mode, or as D[7:0] in Non-multiplexed mode). See Section “16. External Data Memory Interface and On-Chip XRAM” on page 187 for more information about the External Memory Interface. SFR Definition 17.23. P7MDOUT: Port7 Output 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: 0x9F SFR Page: F Bits7-0: P7MDOUT.[7:0]: Port7 Output Mode Bits. 0: Port Pin output mode is configured as Open-Drain. 1: Port Pin output mode is configured as Push-Pull. Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are always configured as Open-Drain when they appear on Port pins. Rev. 1.6 225 C8051F040/1/2/3/4/5/6/7 18. Controller Area Network (CAN0) IMPORTANT DOCUMENTATION NOTE: The Bosch CAN Controller is integrated in the C8051F04x Family of devices. This section of the data sheet gives a description of the CAN controller as an overview and offers a description of how the Silicon Labs CIP-51 MCU interfaces with the on-chip Bosch CAN controller. In order to use the CAN controller, please refer to Bosch’s C_CAN User’s Manual (revision 1.2) as an accompanying manual to Silicon Labs’ C8051F04x Data sheet. The C8051F04x family of devices feature a Control Area Network (CAN) controller that enables serial communication using the CAN protocol. Silicon Labs CAN facilitates communication on a CAN network in accordance with the Bosch specification 2.0A (basic CAN) and 2.0B (full CAN). The CAN controller consists of a CAN Core, Message RAM (separate from the CIP-51 RAM), a message handler state machine, and control registers. Silicon Labs CAN is a protocol controller and does not provide physical layer drivers (i.e., transceivers). Figure 18.1 shows an example typical configuration on a CAN bus. Silicon Labs CAN operates at bit rates of up to 1 Mbit/second, though this can be limited by the physical layer chosen to transmit data on the CAN bus. The CAN processor has 32 Message Objects that can be configured to transmit or receive data. Incoming data, message objects and their identifier masks are stored in the CAN message RAM. All protocol functions for transmission of data and acceptance filtering is performed by the CAN controller and not by the CIP-51 MCU. In this way, minimal CPU bandwidth is needed to use CAN communication. The CIP-51 configures the CAN controller, accesses received data, and passes data for transmission via Special Function Registers (SFRs) in the CIP-51. Figure 18.1. Typical CAN Bus Configuration Rev. 1.6 227 C8051F040/1/2/3/4/5/6/7 18.1. Bosch CAN Controller Operation The CAN Controller featured in the C8051F04x family of devices is a full implementation of Bosch’s full CAN module and fully complies with CAN specification 2.0B. A block diagram of the CAN controller is shown in Figure 18.2. The CAN Core provides shifting (CANTX and CANRX), serial/parallel conversion of messages, and other protocol related tasks such as transmission of data and acceptance filtering. The message RAM stores 32 message objects which can be received or transmitted on a CAN network. The CAN registers and message handler provide an interface for data transfer and notification between the CAN controller and the CIP-51. The function and use of the CAN Controller is detailed in the Bosch CAN User’s Guide. The User’s Guide should be used as a reference to configure and use the CAN controller. This Silicon Labs data sheet describes how to access the CAN controller. The CAN Controller is typically initialized using the following steps: Step 1. Set the SFRPAGE register to CAN0_PAGE. Step 2. Set the INIT the CCE bits to ‘1’ in the CAN0CN Register. See the CAN User’s Guide for bit definitions. Step 3. Set timing parameters in the Bit Timing Register and the BRP Extension Register. Step 4. Initialize each message object or set it’s MsgVal bit to NOT VALID. Step 5. Reset the INIT bit to ‘0’. The CAN Control Register (CAN0CN), CAN Test Register (CAN0TST), and CAN Status Register (CAN0STA) in the CAN controller can be accessed directly or indirectly via CIP-51 SFR’s. All other CAN registers must be accessed via an indirect indexing method described in Section “18.2.5. Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers” on page 232. Figure 18.2. CAN Controller Diagram 228 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 18.1.1. CAN Controller Timing The CAN controller’s system clock (fsys) is derived from the CIP-51 system clock (SYSCLK). Note that an external oscillator (such as a quartz crystal) is typically required due to the high accuracy requirements for CAN communication. Refer to Section “4.10.4 Oscillator Tolerance Range” in the Bosch CAN User’s Guide for further information regarding this topic. 18.1.2. Example Timing Calculation for 1 Mbit/Sec Communication This example shows how to configure the CAN contoller timing parameters for a 1 Mbit/Sec bit rate. Table 18.1 shows timing-related system parameters needed for the calculation. Table 18.1. Background System Information Parameter Value Description External oscillator in ‘Crystal Oscillator Mode’. A 22.1184 MHz quartz crystal is connected between XTAL1 and XTAL2. CIP-51 system clock (SYSCLK) 22.1184 MHz CAN Controller system clock (fsys) 22.1184 MHz Derived from SYSCLK. CAN clock period (tsys) 45.211 ns Derived from 1/fsys. CAN time quantum (tq) 45.211 ns Derived from tsys x BRP1,2 CAN bus length 10 m 5 ns/m signal delay between CAN nodes. Propagation delay time3 400 ns 2 x (transceiver loop delay + bus line delay) Notes: 1. The CAN time quantum (tq) is the smallest unit of time recognized by the CAN contoller. Bit timing parameters are often specified in integer multiples of the time quantum. 2. The Baud Rate Prescaler (BRP) is defined as the value of the BRP Extension Register plus 1. The BRP Extension Register has a reset value of 0x0000; the Baud Rate Prescaler has a reset value of 1. 3. Based on an ISO-11898 compliant transceiver. CAN does not specify a physical layer. Each bit transmitted on a CAN network has 4 segments (Sync_Seg, Prop_Seg, Phase_Seg1, and Phase_Seg2), as shown in Figure 18.3. The sum of these segments determines the CAN bit time (1/bit rate). In this example, the desired bit rate is 1 Mbit/sec; therefore, the desired bit time is 1000 ns. Figure 18.3. Four Segments of a CAN Bit Time Rev. 1.6 229 C8051F040/1/2/3/4/5/6/7 We will adjust the length of the 4 bit segments so that their sum is as close as possible to the desired bit time. Since each segment must be an integer multiple of the time quantum (tq), the closest achievable bit time is 22 tq (994.642 ns), yielding a bit rate of 1.00539 Mbit/sec. The Sync_Seg is a constant 1 tq. The Prop_Seg must be greater than or equal to the propagation delay of 400 ns; we choose 9 tq (406.899 ns). The remaining time quanta (tq) in the bit time are divided between Phase_Seg1 and Phase_Seg2 as shown in Figure 18.1. We select Phase_Seg1 = 6 tq and Phase_Seg2 = 6 tq. Phase_Seg1 + Phase_Seg2 = Bit Time –  Sync_Seg + Prop_Seg  Note 1: If Phase_Seg1 + Phase_Seg2 is even, then Phase_Seg2 = Phase_Seg1. Note 2: Phase_Seg2 should be at least 2 tq. Equation 18.1. Assigning the Phase Segments The Synchronization Jump Width (SJW) timing parameter is defined by Figure 18.2. It is used for determining the value written to the Bit Timing Register and for determining the required oscillator tolerance. Since we are using a quartz crystal as the system clock source, an oscillator tolerance calculation is not needed. SJW = min ( 4, Phase_Seg1 ) Equation 18.2. Synchronization Jump Width (SJW) The value written to the Bit Timing Register can be calculated using Equation 18.3. The BRP Extension register is left at its reset value of 0x0000. BRPE = BRP - 1 = BRP Extension Register = 0x0000 SJWp = SJW - 1 = min ( 4, 6 ) – 1 = 3 TSEG1 = (Prop_Seg + Phase_Seg1 - 1) = 9 + 6 - 1 = 14 TSEG2 = (Phase_Seg2 - 1) = 5 Bit Timing Register = (TSEG2 * 0x1000) + (TSEG1 * 0x0100) + (SJWp * 0x0040) + BRPE = 0x5EC0 Equation 18.3. Calculating the Bit Timing Register Value The following steps are performed to initialize the CAN timing registers: Step 1. Set the SFRPAGE register to CAN0_PAGE. Step 2. Set the INIT the CCE bits to ‘1’ in the CAN Control Register accessible through the CAN0CN SFR. Step 3. Set the CAN0ADR to 0x03 to point to the Bit Timing Register. 230 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Step 4. Write the value 0x5EC0 to the [CAN0DATH:CAN0DATL] CIP-51 SFRs to set the Bit Timing Register using the indirect indexing method described on Section 18.2.5 on page 232. Step 5. Perform other CAN initializations. 18.2. CAN Registers CAN registers are classified as follows: 1. CAN Controller Protocol Registers: CAN control, interrupt, error control, bus status, test modes. 2. Message Object Interface Registers: Used to configure 32 Message Objects, send and receive data to and from Message Objects. The CIP-51 MCU accesses the CAN message RAM via the Message Object Interface Registers. Upon writing a message object number to an IF1 or IF2 Command Request Register, the contents of the associated Interface Registers (IF1 or IF2) will be transferred to or from the message object in CAN RAM. 3. Message Handler Registers: These read only registers are used to provide information to the CIP-51 MCU about the message objects (MSGVLD flags, Transmission Request Pending, New Data Flags) and Interrupts Pending (which Message Objects have caused an interrupt or status interrupt condition). 4. CIP-51 MCU Special Function Registers (SFR): Six registers located in the CIP-51 MCU memory map that allow direct access to certain CAN Controller Protocol Registers, and Indexed indirect access to all CAN registers. 18.2.1. CAN Controller Protocol Registers The CAN Control Protocol Registers are used to configure the CAN controller, process interrupts, monitor bus status, and place the controller in test modes. The CAN controller protocol registers are accessible using CIP-51 MCU SFR’s by an indexed method, and some can be accessed directly by addressing the SFR’s in the CIP-51 SFR map for convenience. The registers are: CAN Control Register (CAN0CN), CAN Status Register (CAN0STA), CAN Test Register (CAN0TST), Error Counter Register, Bit Timing Register, and the Baud Rate Prescaler (BRP) Extension Register. CAN0STA, CAN0CN, and CAN0TST can be accessed via CIP-51 MCU SFR’s. All others are accessed indirectly using the CAN address indexed method via CAN0ADR, CAN0DATH, and CAN0DATL. Please refer to the Bosch CAN User’s Guide for information on the function and use of the CAN Control Protocol Registers. 18.2.2. Message Object Interface Registers There are two sets of Message Object Interface Registers used to configure the 32 Message Objects that transmit and receive data to and from the CAN bus. Message objects can be configured for transmit or receive, and are assigned arbitration message identifiers for acceptance filtering by all CAN nodes. Message Objects are stored in Message RAM, and are accessed and configured using the Message Object Interface Registers. These registers are accessed via the CIP-51’s CAN0ADR and CAN0DAT registers using the indirect indexed address method. Please refer to the Bosch CAN User’s Guide for information on the function and use of the Message Object Interface Registers. Rev. 1.6 231 C8051F040/1/2/3/4/5/6/7 18.2.3. Message Handler Registers The Message Handler Registers are read only registers. Their flags can be read via the indexed access method with CAN0ADR, CAN0DATH, and CAN0DATL. The message handler registers provide interrupt, error, transmit/receive requests, and new data information. Please refer to the Bosch CAN User’s Guide for information on the function and use of the Message Handler Registers. 18.2.4. CIP-51 MCU Special Function Registers C8051F04x family peripherals are modified, monitored, and controlled using Special Function Registers (SFR’s). Only three of the CAN Controller’s registers may be accessed directly with SFR’s. However, all CAN Controller registers can be accessed indirectly using three CIP-51 MCU SFR’s: the CAN Data Registers (CAN0DATH and CAN0DATL) and CAN Address Register (CAN0ADR). 18.2.5. Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers Each CAN Controller Register has an index number (see Table 18.2). The CAN register address space is 128 words (256 bytes). A CAN register is accessed via the CAN Data Registers (CAN0DATH and CAN0DATL) when a CAN register’s index number is placed into the CAN Address Register (CAN0ADR). For example, if the Bit Timing Register is to be configured with a new value, CAN0ADR is loaded with 0x03. The low byte of the desired value is accessed using CAN0DATL and the high byte of the bit timing register is accessed using CAN0DATH. CAN0DATL is bit addressable for convenience. To load the value 0x2304 into the Bit Timing Register: CAN0ADR = 0x03; CAN0DATH = 0x23; CAN0DATL = 0x04; // Load Bit Timing Register’s index (Table 18.1) // Move the upper byte into data reg high byte // Move the lower byte into data reg low byte Note: CAN0CN, CAN0STA, and CAN0TST may be accessed either by using the index method, or by direct access with the CIP-51 MCU SFR’s. CAN0CN is located at SFR location 0xF8/SFR page 1 (SFR Definition 18.3), CAN0TST at 0xDB/SFR page 1 (SFR Definition 18.4), and CAN0STA at 0xC0/SFR page 1 (SFR Definition 18.5). 18.2.6. CAN0ADR Autoincrement Feature For ease of programming message objects, CAN0ADR features autoincrementing for the index ranges 0x08 to 0x12 (Interface Registers 1) and 0x20 to 0x2A (Interface Registers 2). When the CAN0ADR register has an index in these ranges, the CAN0ADR will autoincrement by 1 to point to the next CAN register 16-bit word upon a read/write of CAN0DATL. This speeds programming of the frequentlyaccessed interface registers when configuring message objects. NOTE: Table 18.2 below supersedes Figure 5 in Section 3, “Programmer’s Model” of the Bosch CAN User’s Guide. 232 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 Table 18.2. CAN Register Index and Reset Values CAN Register Index 0x00 0x01 0x02 0x03 0x04 0x05 0x06 CAN Control Register Status Register Error Register Bit Timing Register Interrupt Register Test Register BRP Extension Register Reset Value 0x0001 0x0000 0x0000 0x2301 0x0000 0x0000 0x0000 0x08 IF1 Command Request 0x0001 0x09 IF1 Command Mask 0x0000 0x0A IF1 Mask 1 0xFFFF 0x0B IF1 Mask 2 0xFFFF 0x0C IF1 Arbitration 1 0x0000 0x0D IF1 Arbitration 2 0x0000 0x0E IF1 Message Control 0x0000 0x0F IF1 Data A1 0x0000 0x10 IF1 Data A2 0x0000 0x11 IF1 Data B1 0x0000 0x12 IF1 Data B2 0x0000 0x20 IF2 Command Request 0x0001 0x21 IF2 Command Mask 0x0000 0x22 IF2 Mask 1 0xFFFF 0x23 IF2 Mask 2 0xFFFF 0x24 IF2 Arbitration 1 0x0000 0x25 IF2 Arbitration 2 0x0000 Register Name Notes Accessible in CIP-51 SFR Map Accessible in CIP-51 SFR Map Read Only Write Enabled by CCE Bit in CAN0CN Read Only Bit 7 (RX) is determined by CAN bus Write Enabled by TEST bit in CAN0CN CAN0ADR autoincrements in IF1 index space (0x08 - 0x12) upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrements in IF2 index space (0x20 - 0x2A) upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL Rev. 1.6 233 C8051F040/1/2/3/4/5/6/7 Table 18.2. CAN Register Index and Reset Values (Continued) CAN Register Index Register Name Reset Value 0x26 IF2 Message Control 0x0000 0x27 IF2 Data A1 0x0000 0x28 IF2 Data A2 0x0000 0x29 IF2 Data B1 0x0000 0x2A IF2 Data B2 0x0000 0x40 Transmission Request 1 0x0000 0x41 Transmission Request 2 0x0000 0x48 0x49 New Data 1 New Data 2 0x0000 0x0000 0x50 Interrupt Pending 1 0x0000 0x51 Interrupt Pending 2 0x0000 0x58 Message Valid 1 0x0000 0x59 Message Valid 2 0x0000 Notes CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL CAN0ADR autoincrement upon write to CAN0DATL Transmission request flags for message objects (read only) Transmission request flags for message objects (read only) New Data flags for message objects (read only) New Data flags for message objects (read only) Interrupt pending flags for message objects (read only) Interrupt pending flags for message objects (read only) Message valid flags for message objects (read only) Message valid flags for message objects (read only) Figure 18.4. CAN0DATH: CAN Data Access Register High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit7-0: 234 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD9 SFR Page: 1 CAN0DATH: CAN Data Access Register High Byte. The CAN0DAT Registers are used to read/write register values and data to and from the CAN Registers pointed to with the index number in the CAN0ADR Register. The CAN0ADR Register is used to point the [CAN0DATH:CAN0DATL] to a desired CAN Register. The desired CAN Register’s index number is moved into CAN0ADR. The CAN0DAT Register can then read/write to and from the CAN Register. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 18.1. CAN0DATL: CAN Data Access Register 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 00000001 Bit7-0: Bit0 SFR Address: 0xD8 SFR Page: 1 CAN0DATL: CAN Data Access Register Low Byte. The CAN0DAT Registers are used to read/write register values and data to and from the CAN Registers pointed to with the index number in the CAN0ADR Register. The CAN0ADR Register is used to point the [CAN0DATH:CAN0DATL] to a desired CAN Register. The desired CAN Register’s index number is moved into CAN0ADR. The CAN0DAT Register can then read/write to and from the CAN Register. SFR Definition 18.2. CAN0ADR: CAN Address Index 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 Bit7-0: Bit0 SFR Address: 0xDA SFR Page: 1 CAN0ADR: CAN Address Index Register. The CAN0ADR Register is used to point the [CAN0DATH:CAN0DATL] to a desired CAN Register. The desired CAN Register’s index number is moved into CAN0ADR. The CAN0DAT Register can then read/write to and from the CAN Register. Note: When the value of CAN0ADR is 0x08-0x12 and 0x20-0x2A (IF1 and IF2 registers), this register will autoincrement by 1 upon a write to CAN0DATL. See Section “18.2.6. CAN0ADR Autoincrement Feature” on page 232. All CAN registers’ functions/definitions are listed and described in the Bosch CAN User’s Guide. Rev. 1.6 235 C8051F040/1/2/3/4/5/6/7 SFR Definition 18.3. CAN0CN: CAN Control R/W R/W R/W R R/W R/W R/W * * * CANIF * * * Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit 4: R/W Reset Value * Bit0 SFR Address: 0xF8 SFR Page: 1 CANIF: CAN Interrupt Flag. Write = don’t care. 0: CAN interrupt has not occurred. 1: CAN interrupt has occurred and is active. CANIF is controlled by the CAN controller and is cleared by hardware once all interrupt conditions have been cleared in the CAN controller. See Section 3.4.1 in the Bosch CAN User’s Guide (page 24) for more information concerning CAN controller interrupts. *All CAN registers’ functions/definitions are listed and described in the Bosch CAN User’s Guide with the exception of the CANIF bit. This register may be accessed directly in the CIP-51 SFR register space, or through the indirect, index method (See Section “18.2.5. Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers” on page 232). SFR Definition 18.4. CAN0TST: CAN Test R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Please see the Bosch CAN User’s Guide for a complete definition of this register Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xDB SFR Page: 1 All CAN registers’ functions/definitions are listed and described in the Bosch CAN User’s Guide. This register may be accessed directly in the CIP-51 SFR register space, or through the indirect, index method (See Section “18.2.5. Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers” on page 232). 236 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 18.5. CAN0STA: CAN Status R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Please see the Bosch CAN User’s Guide for a complete definition of this register Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC0 SFR Page: 1 All CAN registers’ functions/definitions are listed and described in the Bosch CAN User’s Guide. This register may be accessed directly in the CIP-51 SFR register space, or through the indirect, index method (See Section “18.2.5. Using CAN0ADR, CAN0DATH, and CANDATL to Access CAN Registers” on page 232). Rev. 1.6 237 C8051F040/1/2/3/4/5/6/7 19. System Management BUS/I2C BUS (SMBUS0) The SMBus0 I/O interface is a two-wire, bi-directional serial bus. SMBus0 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 SMBus0 interface autonomously controlling the serial transfer of the data. A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. SMBus0 may operate as a master and/or slave, and may function on a bus with multiple masters. SMBus0 provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. SMBus0 is controlled by SFRs as described in Section 19.4 on page 245. Figure 19.1. SMBus0 Block Diagram Rev. 1.6 239 C8051F040/1/2/3/4/5/6/7 Figure 19.2 shows a typical SMBus configuration. The SMBus0 interface will work at any voltage between 3.0 V and 5.0 V and 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 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 will not exceed 300 ns and 1000 ns, respectively. Figure 19.2. Typical SMBus Configuration 19.1. Supporting Documents It is assumed the reader is familiar with or has access to the following supporting documents: • • 240 I2C Manual (AN10216-01) -- March 24, 2003, Philips Semiconductor. System Management Bus Specification -- Version 1.1, SBS Implementers Forum. Rev. 1.6 C8051F040/1/2/3/4/5/6/7 19.2. SMBus Protocol 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. Note: 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 that transfer. A typical SMBus transaction consists of a START condition followed by an address byte (Bits7-1: 7-bit slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see Figure 19.3). If the receiving device does not ACK, the transmitting device will read a “not acknowledge” (NACK), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address. 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 one byte at a time and expects an ACK from the slave at the end of each byte. For READ operations, the slave transmits the data and expects 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 19.3 illustrates a typical SMBus transaction. Figure 19.3. SMBus Transaction 19.2.1. 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 19.2.4). 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 give up the bus. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer. This arbitration scheme is nondestructive: one device always wins, and no data is lost. Rev. 1.6 241 C8051F040/1/2/3/4/5/6/7 19.2.2. 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. 19.2.3. 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. 19.2.4. 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. If an SMBus device is waiting to generate a Master START, the START will be generated following the bus free timeout. 19.3. SMBus Transfer Modes The SMBus0 interface may be configured to operate as a master and/or a slave. At any particular time, the interface will be operating in one of the following modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. See Table 19.1 for transfer mode status decoding using the SMB0STA status register. The following mode descriptions illustrate an interrupt-driven SMBus0 application; SMBus0 may alternatively be operated in polled mode. 19.3.1. Master Transmitter Mode Serial data is transmitted on SDA while the serial clock is output on SCL. SMBus0 generates a START condition and then transmits the first byte containing the address of the target slave device and the data direction bit. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The SMBus0 interface transmits one or more bytes of serial data, waiting for an acknowledge (ACK) from the slave after each byte. To indicate the end of the serial transfer, SMBus0 generates a STOP condition. Figure 19.4. Typical Master Transmitter Sequence 242 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 19.3.2. Master Receiver Mode Serial data is received on SDA while the serial clock is output on SCL. The SMBus0 interface generates a START followed by the first data 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 to indicate a "READ" operation. The SMBus0 interface receives serial data from the slave and generates the clock on SCL. After each byte is received, SMBus0 generates an ACK or NACK depending on the state of the AA bit in register SMB0CN. SMBus0 generates a STOP condition to indicate the end of the serial transfer. Figure 19.5. Typical Master Receiver Sequence 19.3.3. Slave Transmitter Mode Serial data is transmitted on SDA while the serial clock is received on SCL. The SMBus0 interface receives a START followed by data byte containing the slave address and direction bit. If the received slave address matches the address held in register SMB0ADR, the SMBus0 interface generates an ACK. SMBus0 will also ACK if the general call address (0x00) is received and the General Call Address Enable bit (SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 1 to indicate a "READ" operation. The SMBus0 interface receives the clock on SCL and transmits one or more bytes of serial data, waiting for an ACK from the master after each byte. SMBus0 exits slave mode after receiving a STOP condition from the master. Figure 19.6. Typical Slave Transmitter Sequence Rev. 1.6 243 C8051F040/1/2/3/4/5/6/7 19.3.4. Slave Receiver Mode Serial data is received on SDA while the serial clock is received on SCL. The SMBus0 interface receives a START followed by data byte containing the slave address and direction bit. If the received slave address matches the address held in register SMB0ADR, the interface generates an ACK. SMBus0 will also ACK if the general call address (0x00) is received and the General Call Address Enable bit (SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The SMBus0 interface receives one or more bytes of serial data; after each byte is received, the interface transmits an ACK or NACK depending on the state of the AA bit in SMB0CN. SMBus0 exits Slave Receiver Mode after receiving a STOP condition from the master. Figure 19.7. Typical Slave Receiver Sequence 244 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 19.4. SMBus Special Function Registers The SMBus0 serial interface is accessed and controlled through five SFRs: SMB0CN Control Register, SMB0CR Clock Rate Register, SMB0ADR Address Register, SMB0DAT Data Register and SMB0STA Status Register. The five special function registers related to the operation of the SMBus0 interface are described in the following sections. 19.4.1. Control Register The SMBus0 Control register SMB0CN is used to configure and control the SMBus0 interface. All of the bits in the register can be read or written by software. Two of the control bits are also affected by the SMBus0 hardware. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by the hardware when a valid serial interrupt condition occurs. It can only be cleared by software. The Stop flag (STO, SMB0CN.4) is set to logic 1 by software. It is cleared to logic 0 by hardware when a STOP condition is detected on the bus. Setting the ENSMB flag to logic 1 enables the SMBus0 interface. Clearing the ENSMB flag to logic 0 disables the SMBus0 interface and removes it from the bus. Momentarily clearing the ENSMB flag and then resetting it to logic 1 will reset SMBus0 communication. However, ENSMB should not be used to temporarily remove a device from the bus since the bus state information will be lost. Instead, the Assert Acknowledge (AA) flag should be used to temporarily remove the device from the bus (see description of AA flag below). Setting the Start flag (STA, SMB0CN.5) to logic 1 will put SMBus0 in a master mode. If the bus is free, SMBus0 will generate a START condition. If the bus is not free, SMBus0 waits for a STOP condition to free the bus and then generates a START condition after a 5 μs delay per the SMB0CR value (In accordance with the SMBus protocol, the SMBus0 interface also considers the bus free if the bus is idle for 50 μs and no STOP condition was recognized). If STA is set to logic 1 while SMBus0 is in master mode and one or more bytes have been transferred, a repeated START condition will be generated. When the Stop flag (STO, SMB0CN.4) is set to logic 1 while the SMBus0 interface is in master mode, the interface generates a STOP condition. In a slave mode, the STO flag may be used to recover from an error condition. In this case, a STOP condition is not generated on the bus, but the SMBus hardware behaves as if a STOP condition has been received and enters the "not addressed" slave receiver mode. Note that this simulated STOP will not cause the bus to appear free to SMBus0. The bus will remain occupied until a STOP appears on the bus or a Bus Free Timeout occurs. Hardware automatically clears the STO flag to logic 0 when a STOP condition is detected on the bus. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by hardware when the SMBus0 interface enters any one of the 28 possible states except the Idle state. If interrupts are enabled for the SMBus0 interface, an interrupt request is generated when the SI flag is set. The SI flag must be cleared by software. Important Note: If SI is set to logic 1 while the SCL line is low, the clock-low period of the serial clock will be stretched and the serial transfer is suspended until SI is cleared to logic 0. A high level on SCL is not affected by the setting of the SI flag. The Assert Acknowledge flag (AA, SMB0CN.2) is used to set the level of the SDA line during the acknowledge clock cycle on the SCL line. Setting the AA flag to logic 1 will cause an ACK (low level on SDA) to be sent during the acknowledge cycle if the device has been addressed. Setting the AA flag to logic 0 will cause a NACK (high level on SDA) to be sent during acknowledge cycle. After the transmission of a byte in slave mode, the slave can be temporarily removed from the bus by clearing the AA flag. The slave's own address and general call address will be ignored. To resume operation on the bus, the AA flag must be reset to logic 1 to allow the slave's address to be recognized. Rev. 1.6 245 C8051F040/1/2/3/4/5/6/7 Setting the SMBus0 Free Timer Enable bit (FTE, SMB0CN.1) to logic 1 enables the timer in SMB0CR. When SCL goes high, the timer in SMB0CR counts up. A timer overflow indicates a free bus timeout: if SMBus0 is waiting to generate a START, it will do so after this timeout. The bus free period should be less than 50 μs (see SFR Definition 19.2, SMBus0 Clock Rate Register). When the TOE bit in SMB0CN is set to logic 1, Timer 4 is used to detect SCL low timeouts. If Timer 4 is enabled (see Section “23.2. Timer 2, Timer 3, and Timer 4” on page 297), Timer 4 is forced to reload when SCL is high, and forced to count when SCL is low. With Timer 4 enabled and configured to overflow after 25 ms (and TOE set), a Timer 4 overflow indicates a SCL low timeout; the Timer 4 interrupt service routine can then be used to reset SMBus0 communication in the event of an SCL low timeout. 246 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 19.1. SMB0CN: SMBus0 Control R R/W R/W R/W R/W R/W R/W R/W Reset Value BUSY ENSMB STA STO SI AA FTE TOE 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Bit Addressable SFR Address: 0xC0 SFR Page: 0 Bit0 BUSY: Busy Status Flag. 0: SMBus0 is free 1: SMBus0 is busy ENSMB: SMBus Enable. This bit enables/disables the SMBus serial interface. 0: SMBus0 disabled. 1: SMBus0 enabled. STA: SMBus Start Flag. 0: No START condition is transmitted. 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.) If STA is set after one or more bytes have been transmitted or received and before a STOP is received, a repeated START condition is transmitted. STO: SMBus Stop Flag. 0: No STOP condition is transmitted. 1: Setting STO to logic 1 causes a STOP condition to be transmitted. When a STOP condition is received, hardware clears STO to logic 0. If both STA and STO are set, a STOP condition is transmitted followed by a START condition. In slave mode, setting the STO flag causes SMBus to behave as if a STOP condition was received. SI: SMBus Serial Interrupt Flag. This bit is set by hardware when one of 27 possible SMBus0 states is entered. (Status code 0xF8 does not cause SI to be set.) When the SI interrupt is enabled, setting this bit causes the CPU to vector to the SMBus interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. AA: SMBus Assert Acknowledge Flag. This bit defines the type of acknowledge returned during the acknowledge cycle on the SCL line. 0: A "not acknowledge" (high level on SDA) is returned during the acknowledge cycle. 1: An "acknowledge" (low level on SDA) is returned during the acknowledge cycle. FTE: SMBus Free Timer Enable Bit 0: No timeout when SCL is high 1: Timeout when SCL high time exceeds limit specified by the SMB0CR value. TOE: SMBus Timeout Enable Bit 0: No timeout when SCL is low. 1: Timeout when SCL low time exceeds limit specified by Timer 4, if enabled. Rev. 1.6 247 C8051F040/1/2/3/4/5/6/7 19.4.2. Clock Rate Register SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bits7-0: Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xCF SFR Page: 0 SMB0CR.[7:0]: SMBus0 Clock Rate Preset The SMB0CR Clock Rate register controls the frequency of the serial clock SCL in master mode. The 8-bit word stored in the SMB0CR Register preloads a dedicated 8-bit timer. The timer counts up, and when it rolls over to 0x00, the SCL logic state toggles. The SMB0CR setting should be bounded by the following equation, where SMB0CR is the unsigned 8-bit value in register SMB0CR, and SYSCLK is the system clock frequency in Hz: SMB0C R    288 – 0.85  SYSCLK   1.124 E 6  The resulting SCL signal high and low times are given by the following equations: T LOW =  256 – SMB0CR   SYSCLK T HIGH   258 – SMB0CR   SYSCLK + 625ns Using the same value of SMB0CR from above, the Bus Free Timeout period is given in the following equation:  256 – SMB0CR  + 1 T BFT  10  ----------------------------------------------------SYSCLK 248 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 19.4.3. Data Register The SMBus0 Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software can read or write to this register while the SI flag is set to logic 1; software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag reads logic 0 since the hardware may be in the process of shifting a byte of data in 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. Therefore, 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 in SMB0DAT. SFR Definition 19.3. SMB0DAT: SMBus0 Data 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 Bits7-0: Bit0 SFR Address: 0xC2 SFR Page: 0 SMB0DAT: SMBus0 Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus0 serial interface or a byte that has just been received on the SMBus0 serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.3) is set to logic 1. When the SI flag is not set, the system may be in the process of shifting data and the CPU should not attempt to access this register. 19.4.4. Address Register The SMB0ADR Address register holds the slave address for the SMBus0 interface. In slave mode, the seven most-significant bits hold the 7-bit slave address. The least significant bit (Bit0) is used to enable the recognition of the general call address (0x00). If Bit0 is set to logic 1, the general call address will be recognized. Otherwise, the general call address is ignored. The contents of this register are ignored when SMBus0 is operating in master mode. Rev. 1.6 249 C8051F040/1/2/3/4/5/6/7 SFR Definition 19.4. SMB0ADR: SMBus0 Address R/W R/W R/W R/W R/W R/W R/W R/W Reset Value SLV6 SLV5 SLV4 SLV3 SLV2 SLV1 SLV0 GC 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC3 SFR Page: 0 Bits7-1: SLV6-SLV0: SMBus0 Slave Address. These bits are loaded with the 7-bit slave address to which SMBus0 will respond when operating as a slave transmitter or slave receiver. SLV6 is the most significant bit of the address and corresponds to the first bit of the address byte received. Bit0: GC: General Call Address Enable. This bit is used to enable general call address (0x00) recognition. 0: General call address is ignored. 1: General call address is recognized. 19.4.5. Status Register The SMB0STA Status register holds an 8-bit status code indicating the current state of the SMBus0 interface. There are 28 possible SMBus0 states, each with a corresponding unique status code. The five most significant bits of the status code vary while the three least-significant bits of a valid status code are fixed at zero when SI = ‘1’. Therefore, all possible status codes are multiples of eight. This facilitates the use of status codes in software as an index used to branch to appropriate service routines (allowing 8 bytes of code to service the state or jump to a more extensive service routine). For the purposes of user software, the contents of the SMB0STA register is only defined when the SI flag is logic 1. Software should never write to the SMB0STA register; doing so will yield indeterminate results. The 28 SMBus0 states, along with their corresponding status codes, are given in Table 19.1. 250 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 19.5. SMB0STA: SMBus0 Status R/W R/W R/W R/W R/W R/W R/W R/W Reset Value STA7 STA6 STA5 STA4 STA3 STA2 STA1 STA0 11111000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC1 SFR Page: 0 Bits7-3: STA7-STA3: SMBus0 Status Code. These bits contain the SMBus0 Status Code. There are 28 possible status codes; each status code corresponds to a single SMBus state. A valid status code is present in SMB0STA when the SI flag (SMB0CN.3) is set to logic 1. The content of SMB0STA is not defined when the SI flag is logic 0. Writing to the SMB0STA register at any time will yield indeterminate results. Bits2-0: STA2-STA0: The three least significant bits of SMB0STA are always read as logic 0 when the SI flag is logic 1. Rev. 1.6 251 C8051F040/1/2/3/4/5/6/7 Table 19.1. SMB0STA Status Codes and States Master Receiver Master Transmitter MT/ MR Mode 252 Status Code SMBus State Typical Action 0x08 START condition transmitted. Load SMB0DAT with Slave Address + R/W. Clear STA. 0x10 Repeated START condition transmitted. Load SMB0DAT with Slave Address + R/W. Clear STA. 0x18 Slave Address + W transmitted. ACK received. Load SMB0DAT with data to be transmitted. 0x20 Slave Address + W transmitted. NACK received. Acknowledge poll to retry. Set STO + STA. 0x28 Data byte transmitted. ACK received. 0x30 Data byte transmitted. NACK received. 1) Retry transfer OR 2) Set STO. 0x38 Arbitration Lost. Save current data. 0x40 Slave Address + R transmitted. ACK received. If only receiving one byte, clear AA (send NACK after received byte). Wait for received data. 0x48 Slave Address + R transmitted. NACK received. Acknowledge poll to retry. Set STO + STA. 0x50 Data byte received. ACK transmitted. Read SMB0DAT. Wait for next byte. If next byte is last byte, clear AA. 0x58 Data byte received. NACK transmitted. Set STO. Rev. 1.6 1) Load SMB0DAT with next byte, OR 2) Set STO, OR 3) Clear STO then set STA for repeated START. C8051F040/1/2/3/4/5/6/7 Table 19.1. SMB0STA Status Codes and States (Continued) All Slave Slave Transmitter Slave Receiver Mode Status Code SMBus State Typical Action 0x60 Own slave address + W received. ACK transmitted. Wait for data. 0x68 Arbitration lost in sending SLA + R/W as master. Own address + W received. ACK transmitted. Save current data for retry when bus is free. Wait for data. 0x70 General call address received. ACK transmitted. Wait for data. 0x78 Arbitration lost in sending SLA + R/W as master. General call address received. ACK transmitted. Save current data for retry when bus is free. 0x80 Data byte received. ACK transmitted. Read SMB0DAT. Wait for next byte or STOP. 0x88 Data byte received. NACK transmitted. Set STO to reset SMBus. 0x90 Data byte received after general call address. ACK transmitted. Read SMB0DAT. Wait for next byte or STOP. 0x98 Data byte received after general call address. NACK transmitted. Set STO to reset SMBus. 0xA0 STOP or repeated START received. No action necessary. 0xA8 Own address + R received. ACK transmitted. Load SMB0DAT with data to transmit. 0xB0 Arbitration lost in transmitting SLA + R/W as master. Own address + R received. ACK transmitted. Save current data for retry when bus is free. Load SMB0DAT with data to transmit. 0xB8 Data byte transmitted. ACK received. Load SMB0DAT with data to transmit. 0xC0 Data byte transmitted. NACK received. Wait for STOP. 0xC8 Last data byte transmitted (AA=0). ACK received. Set STO to reset SMBus. 0xD0 SCL Clock High Timer per SMB0CR timed out Set STO to reset SMBus. 0x00 Bus Error (illegal START or STOP) Set STO to reset SMBus. 0xF8 Idle State does not set SI. Rev. 1.6 253 C8051F040/1/2/3/4/5/6/7 20. Enhanced Serial Peripheral Interface (SPI0) The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports 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 20.1. SPI Block Diagram Rev. 1.6 255 C8051F040/1/2/3/4/5/6/7 20.1. Signal Descriptions The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below. 20.1.1. 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. 20.1.2. 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. 20.1.3. 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. 20.1.4. 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 can 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 20.2, Figure 20.3, and Figure 20.4 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 “17.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 204 for general purpose port I/O and crossbar information. 256 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 20.2. SPI0 Master Mode Operation A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0 must be manually re-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins. Figure 20.2 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 does not get 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 20.3 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 20.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices. Rev. 1.6 257 C8051F040/1/2/3/4/5/6/7 Figure 20.2. Multiple-Master Mode Connection Diagram Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram 258 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 20.3. 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 through 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 doublebuffered, 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 wait until the byte is transferred before loading it with the transmit buffer’s contents. 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 20.4 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 does not get mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and re-enabling SPI0 with the SPIEN bit. Figure 20.3 shows a connection diagram between a slave device in 3-wire slave mode and a master device. 20.4. SPI0 Interrupt Sources When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: Note: 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, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost. Rev. 1.6 259 C8051F040/1/2/3/4/5/6/7 20.5. Serial Clock Timing As shown in Figure 20.5, four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an activehigh or active-low clock. Both master and slave devices must be configured to use the same clock phase and polarity. Note: SPI0 should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. Note that in master mode, the SPI samples MISO one system clock before the inactive edge of SCK (the edge where MOSI changes state) to provide maximum settling time for the slave device. The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 20.3 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. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-wire slave mode), and the serial input data synchronously with the 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 system clock. Figure 20.5. Data/Clock Timing Diagram 260 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 20.6. 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 definitions. SFR Definition 20.1. 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: 0x9A SFR Page: 0 SPIBSY: SPI Busy. 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 sampled on first edge of SCK period. 1: Data sampled 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. 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. 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). 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). 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. Rev. 1.6 261 C8051F040/1/2/3/4/5/6/7 SFR Definition 20.2. 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 SFR Page: 0 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 (and generates a SPI0 interrupt) to indicate a write to the SPI0 data register was attempted while a data transfer was in progress. 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 “20.2. SPI0 Master Mode Operation” on page 257 and Section “20.3. SPI0 Slave Mode Operation” on page 259). 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. 262 Rev. 1.6 C8051F040/1/2/3/4/5/6/7 SFR Definition 20.3. 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: 0x9D SFR Page: 0 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