C8051F920-G-GM

C8051F93x-C8051F92x Single/Dual Battery, 0.9–3.6 V, 64/32 kB, SmaRTClock, 10-Bit ADC MCU Supply Voltage 0.9 to 3.6 V - One-Cell Mode supports 0.9 to 1.8 V operation - Two-Cell Mode supports 1.8 to 3.6 V operation - Built-in dc-dc converter with 1.8 to 3.3 V output for High-Speed 8051 µC Core - Pipelined instruction architecture; executes 70% of instructions in 1 or 2 system clocks use in one-cell mode Built-in LDO regulator allows a high analog supply voltage and low digital core voltage - 2 built-in supply monitors (brownout detectors) 10-Bit Analog to Digital Converter - ±1 LSB INL; no missing codes - Programmable throughput up to 300 ksps - Up to 23 external inputs - On-Chip Voltage Reference - On-Chip PGA allows measuring voltages up to twice the reference voltage - 16-bit Auto-Averaging Accumulator with Burst Mode provides increased ADC resolution - Data dependent windowed interrupt generator - Built-in temperature sensor - Two Comparators - Programmable hysteresis and response time - Configurable as wake-up or reset source - Up to 23 Capacitive Touch Sense Inputs 6-Bit Programmable Current Reference - Up to ±500 µA. Can be used as a bias or for - supports UART operation; 20 MHz low power oscillator requires very little bias current External oscillator: Crystal, RC, C, or CMOS Clock SmaRTClock oscillator: 32 kHz Crystal or internal self-oscillate mode Can switch between clock sources on-the-fly; useful in implementing various power saving modes + + – – VOLTAGE COMPARATORS CROSSBAR IREF DIGITAL I/O UART SMBus 2 x SPI PCA Timer 0 Timer 1 Timer 2 Timer 3 CRC EMIF 10-bit 300 ksps ADC VREG - Packages - 32-pin QFN (5 x 5 mm) - 24-pin QFN (4 x 4 mm) - 32-pin LQFP (7 x 7 mm, easy to hand-solder) Temperature Range: –40 to +85 °C ANALOG PERIPHERALS VREF current and programmable drive strengthHardware SMBus™ (I2C™ Compatible), 2 x SPI™, and UART serial ports available concurrently Four general purpose 16-bit counter/timers Programmable 16-bit counter/timer array with six capture/compare modules and watchdog timer Hardware SmaRTClock operates down to 0.9 V and requires less than 0.5 µA supply current - intrusive in-system debug (no emulator required) Provides breakpoints, single stepping Inspect/modify memory and registers Complete development kit TEMP SENSOR Digital Peripherals - 24 or 16 port I/O; All 5 V tolerant with high sink - generating a custom reference voltage A M U X grammable in 1024-byte sectors—1024 bytes are reserved in the 64 kB devices Clock Sources - Internal oscillators: 24.5 MHz, 2% accuracy On-Chip Debug - On-chip debug circuitry facilitates full-speed, non- - Up to 25 MIPS throughput with 25 MHz clock - Expanded interrupt handler Memory - 4352 bytes internal data RAM (256 + 4096) - 64 kB (‘F93x) or 32 kB (‘F92x) Flash; In-system pro- Port 0 Port 1 Port 2 24.5 MHz PRECISION INTERNAL OSCILLATOR 20 MHz LOW POWER INTERNAL OSCILLATOR External Oscillator HARDWARE SmaRTClock HIGH-SPEED CONTROLLER CORE 64/32 kB ISP FLASH FLEXIBLE INTERRUPTS Rev. 1.4 11/13 8051 CPU (25 MIPS) DEBUG CIRCUITRY 4352 B SRAM POR WDT Copyright © 2013 by Silicon Laboratories C8051F93x-C8051F92x C8051F93x-C8051F92x 2 Rev. 1.4 C8051F93x-C8051F92x Table of Contents 1. System Overview.................................................................................................... 17 1.1. CIP-51™ Microcontroller Core.......................................................................... 20 1.1.1. Fully 8051 Compatible.............................................................................. 20 1.1.2. Improved Throughput ............................................................................... 20 1.1.3. Additional Features .................................................................................. 20 1.2. Port Input/Output............................................................................................... 21 1.3. Serial Ports ....................................................................................................... 22 1.4. Programmable Counter Array ........................................................................... 22 1.5. 10-Bit SAR ADC with 16-bit Auto-Averaging Accumulator and Autonomous Low Power Burst Mode............................................................................................... 23 1.6. Programmable Current Reference (IREF0) ...................................................... 24 1.7. Comparators ..................................................................................................... 24 2. Ordering Information.............................................................................................. 26 3. Pinout and Package Definitions............................................................................ 27 4. Electrical Characteristics....................................................................................... 45 4.1. Absolute Maximum Specifications .................................................................... 45 4.2. Electrical Characteristics................................................................................... 46 5. 10-Bit SAR ADC with 16-bit Auto-Averaging Accumulator and Autonomous Low Power Burst Mode ....................................................................................................... 67 5.1. Output Code Formatting ................................................................................... 68 5.2. Modes of Operation .......................................................................................... 69 5.2.1. Starting a Conversion............................................................................... 69 5.2.2. Tracking Modes........................................................................................ 70 5.2.3. Burst Mode ............................................................................................... 71 5.2.4. Settling Time Requirements ..................................................................... 73 5.2.5. Gain Setting.............................................................................................. 74 5.3. 8-Bit Mode......................................................................................................... 74 5.4. Programmable Window Detector ...................................................................... 81 5.4.1. Window Detector In Single-Ended Mode ................................................. 83 5.4.2. ADC0 Specifications................................................................................. 83 5.5. ADC0 Analog Multiplexer.................................................................................. 84 5.6. Temperature Sensor ......................................................................................... 86 5.6.1. Calibration ................................................................................................ 87 5.7. Voltage and Ground Reference Options........................................................... 89 5.8. External Voltage References ............................................................................ 90 5.9. Internal Voltage References ............................................................................. 90 5.10.Analog Ground Reference................................................................................ 90 5.11.Temperature Sensor Enable ............................................................................ 90 5.12.Voltage Reference Electrical Specifications ..................................................... 91 6. Programmable Current Reference (IREF0) .......................................................... 92 6.1. IREF0 Specifications......................................................................................... 92 7. Comparators ........................................................................................................... 93 7.1. Comparator Inputs ............................................................................................ 93 Rev. 1.4 3 C8051F93x-C8051F92x 7.2. Comparator Outputs ......................................................................................... 94 7.3. Comparator Response Time............................................................................. 95 7.4. Comparator Hysterisis ...................................................................................... 95 7.5. Comparator Register Descriptions.................................................................... 96 7.6. Comparator0 and Comparator1 Analog Multiplexers...................................... 100 8. CIP-51 Microcontroller ......................................................................................... 103 8.1. Instruction Set ................................................................................................. 104 8.1.1. Instruction and CPU Timing ................................................................... 104 8.2. CIP-51 Register Descriptions.......................................................................... 109 9. Memory Organization........................................................................................... 112 9.1. Program Memory ............................................................................................ 113 9.1.1. MOVX Instruction and Program Memory ............................................... 113 9.2. Data Memory .................................................................................................. 114 9.2.1. Internal RAM .......................................................................................... 114 9.2.2. External RAM ......................................................................................... 115 10. External Data Memory Interface and On-Chip XRAM........................................ 116 10.1.Accessing XRAM............................................................................................ 116 10.1.1.16-Bit MOVX Example ........................................................................... 116 10.1.2.8-Bit MOVX Example ............................................................................. 116 10.2.Configuring the External Memory Interface for Off-Chip Access.................... 117 10.3.External Memory Interface Port Input/Output Configuration........................... 117 10.4.Multiplexed External Memory Interface .......................................................... 118 10.5.External Memory Interface Operating Modes................................................. 120 10.5.1.Internal XRAM Only ............................................................................... 120 10.5.2.Split Mode without Bank Select.............................................................. 120 10.5.3.Split Mode with Bank Select................................................................... 121 10.5.4.External Only.......................................................................................... 121 10.6.External Memory Interface Timing.................................................................. 121 10.7.EMIF Special Function Registers ................................................................... 122 10.8.EMIF Timing Diagrams................................................................................... 125 10.8.1.Multiplexed 16-bit MOVX: EMI0CF[3:2] = 01, 10, or 11......................... 125 10.8.2.Multiplexed 8-bit MOVX without Bank Select: EMI0CF[3:2] = 01 or 11. 126 11. Special Function Registers ................................................................................. 129 11.1.SFR Paging .................................................................................................... 130 12. Interrupt Handler .................................................................................................. 136 12.1.Enabling Interrupt Sources ............................................................................. 136 12.2.MCU Interrupt Sources and Vectors............................................................... 136 12.3.Interrupt Priorities ........................................................................................... 137 12.4.Interrupt Latency............................................................................................. 137 12.5.Interrupt Register Descriptions ....................................................................... 139 12.6.External Interrupts INT0 and INT1.................................................................. 146 13. Flash Memory ....................................................................................................... 148 13.1.Programming The Flash Memory ................................................................... 148 13.1.1.Flash Lock and Key Functions ............................................................... 148 13.1.2.Flash Erase Procedure .......................................................................... 149 4 Rev. 1.4 C8051F93x-C8051F92x 13.1.3.Flash Write Procedure ........................................................................... 149 13.2.Non-volatile Data Storage .............................................................................. 150 13.3.Security Options ............................................................................................. 150 13.4.Determining the Device Part Number at Run Time ........................................ 152 13.5.Flash Write and Erase Guidelines .................................................................. 153 13.5.1.VDD Maintenance and the VDD Monitor ............................................... 153 13.5.2.PSWE Maintenance ............................................................................... 154 13.5.3.System Clock ......................................................................................... 154 13.6.Minimizing Flash Read Current ...................................................................... 155 14. Power Management.............................................................................................. 159 14.1.Normal Mode .................................................................................................. 160 14.2.Idle Mode........................................................................................................ 161 14.3.Stop Mode ...................................................................................................... 161 14.4.Suspend Mode ............................................................................................... 162 14.5.Sleep Mode .................................................................................................... 162 14.6.Configuring Wakeup Sources......................................................................... 163 14.7.Determining the Event that Caused the Last Wakeup.................................... 164 14.8.Power Management Specifications ................................................................ 166 15. Cyclic Redundancy Check Unit (CRC0) ............................................................. 167 15.1.16-bit CRC Algorithm...................................................................................... 167 15.2.32-bit CRC Algorithm...................................................................................... 169 15.3.Preparing for a CRC Calculation .................................................................... 170 15.4.Performing a CRC Calculation ....................................................................... 170 15.5.Accessing the CRC0 Result ........................................................................... 170 15.6.CRC0 Bit Reverse Feature............................................................................. 174 16. On-Chip DC-DC Converter (DC0) ........................................................................ 175 16.1.Startup Behavior............................................................................................. 176 16.2.High Power Applications ............................................................................. 177 16.3.Pulse Skipping Mode...................................................................................... 177 16.4.Enabling the DC-DC Converter ...................................................................... 178 16.5.Minimizing Power Supply Noise ..................................................................... 179 16.6.Selecting the Optimum Switch Size................................................................ 179 16.7.DC-DC Converter Clocking Options ............................................................... 179 16.8.DC-DC Converter Behavior in Sleep Mode .................................................... 180 16.9.DC-DC Converter Register Descriptions ........................................................ 181 16.10.DC-DC Converter Specifications .................................................................. 182 17. Voltage Regulator (VREG0) ................................................................................. 183 17.1.Voltage Regulator Electrical Specifications .................................................... 183 18. Reset Sources....................................................................................................... 184 18.1.Power-On (VBAT Supply Monitor) Reset ....................................................... 185 18.2.Power-Fail (VDD/DC+ Supply Monitor) Reset................................................ 186 18.3.External Reset ................................................................................................ 188 18.4.Missing Clock Detector Reset ........................................................................ 188 18.5.Comparator0 Reset ........................................................................................ 188 18.6.PCA Watchdog Timer Reset .......................................................................... 188 Rev. 1.4 5 C8051F93x-C8051F92x 18.7.Flash Error Reset ........................................................................................... 189 18.8.SmaRTClock (Real Time Clock) Reset .......................................................... 189 18.9.Software Reset ............................................................................................... 189 19. Clocking Sources ................................................................................................. 191 19.1.Programmable Precision Internal Oscillator ................................................... 192 19.2.Low Power Internal Oscillator......................................................................... 192 19.3.External Oscillator Drive Circuit...................................................................... 192 19.3.1.External Crystal Mode............................................................................ 192 19.3.2.External RC Mode.................................................................................. 194 19.3.3.External Capacitor Mode........................................................................ 195 19.3.4.External CMOS Clock Mode .................................................................. 196 19.4.Special Function Registers for Selecting and Configuring the System Clock 197 20. SmaRTClock (Real Time Clock) .......................................................................... 200 20.1.SmaRTClock Interface ................................................................................... 201 20.1.1.SmaRTClock Lock and Key Functions................................................... 201 20.1.2.Using RTC0ADR and RTC0DAT to Access SmaRTClock Internal Registers ..................................................................................................... 202 20.1.3.RTC0ADR Short Strobe Feature............................................................ 202 20.1.4.SmaRTClock Interface Autoread Feature .............................................. 203 20.1.5.RTC0ADR Autoincrement Feature......................................................... 203 20.2.SmaRTClock Clocking Sources ..................................................................... 206 20.2.1.Using the SmaRTClock Oscillator with a Crystal or External CMOS Clock ............................................................................ 206 20.2.2.Using the SmaRTClock Oscillator in Self-Oscillate Mode...................... 206 20.2.3.Programmable Load Capacitance.......................................................... 207 20.2.4.Automatic Gain Control (Crystal Mode Only) and SmaRTClock Bias Doubling ......................................................................................... 208 20.2.5.Missing SmaRTClock Detector .............................................................. 210 20.2.6.SmaRTClock Oscillator Crystal Valid Detector ...................................... 210 20.3.SmaRTClock Timer and Alarm Function ........................................................ 210 20.3.1.Setting and Reading the SmaRTClock Timer Value .............................. 210 20.3.2.Setting a SmaRTClock Alarm ................................................................ 211 20.3.3.Software Considerations for using the SmaRTClock Timer and Alarm . 211 21. Port Input/Output.................................................................................................. 216 21.1.Port I/O Modes of Operation........................................................................... 217 21.1.1.Port Pins Configured for Analog I/O....................................................... 217 21.1.2.Port Pins Configured For Digital I/O....................................................... 217 21.1.3.Interfacing Port I/O to 5 V and 3.3 V Logic............................................. 218 21.1.4.Increasing Port I/O Drive Strength ......................................................... 218 21.2.Assigning Port I/O Pins to Analog and Digital Functions................................ 218 21.2.1.Assigning Port I/O Pins to Analog Functions ......................................... 218 21.2.2.Assigning Port I/O Pins to Digital Functions........................................... 220 21.2.3.Assigning Port I/O Pins to External Digital Event Capture Functions .... 220 21.3.Priority Crossbar Decoder .............................................................................. 221 21.4.Port Match ...................................................................................................... 227 6 Rev. 1.4 C8051F93x-C8051F92x 21.5.Special Function Registers for Accessing and Configuring Port I/O .............. 229 22. SMBus ................................................................................................................... 238 22.1.Supporting Documents ................................................................................... 239 22.2.SMBus Configuration...................................................................................... 239 22.3.SMBus Operation ........................................................................................... 240 22.3.1.Transmitter Vs. Receiver........................................................................ 240 22.3.2.Arbitration............................................................................................... 241 22.3.3.Clock Low Extension.............................................................................. 241 22.3.4.SCL Low Timeout................................................................................... 241 22.3.5.SCL High (SMBus Free) Timeout .......................................................... 241 22.4.Using the SMBus............................................................................................ 242 22.4.1.SMBus Configuration Register............................................................... 243 22.4.2.SMB0CN Control Register ..................................................................... 246 22.4.3.Hardware Slave Address Recognition ................................................... 249 22.4.4.Data Register ......................................................................................... 251 22.5.SMBus Transfer Modes.................................................................................. 252 22.5.1.Write Sequence (Master) ....................................................................... 252 22.5.2.Read Sequence (Master) ....................................................................... 253 22.5.3.Write Sequence (Slave) ......................................................................... 254 22.5.4.Read Sequence (Slave) ......................................................................... 255 22.6.SMBus Status Decoding................................................................................. 255 23. UART0.................................................................................................................... 260 23.1.Enhanced Baud Rate Generation................................................................... 261 23.2.Operational Modes ......................................................................................... 262 23.2.1.8-Bit UART ............................................................................................. 262 23.2.2.9-Bit UART ............................................................................................. 263 23.3.Multiprocessor Communications .................................................................... 263 24. Enhanced Serial Peripheral Interface (SPI0 and SPI1)...................................... 268 24.1.Signal Descriptions......................................................................................... 269 24.1.1.Master Out, Slave In (MOSI).................................................................. 269 24.1.2.Master In, Slave Out (MISO).................................................................. 269 24.1.3.Serial Clock (SCK) ................................................................................. 269 24.1.4.Slave Select (NSS) ................................................................................ 269 24.2.SPI Master Mode Operation ........................................................................... 270 24.3.SPI Slave Mode Operation ............................................................................. 272 24.4.SPI Interrupt Sources ..................................................................................... 272 24.5.Serial Clock Phase and Polarity ..................................................................... 273 24.6.SPI Special Function Registers ...................................................................... 275 25. Timers.................................................................................................................... 283 25.1.Timer 0 and Timer 1 ....................................................................................... 285 25.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 285 25.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 286 25.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 287 25.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 288 25.2.Timer 2 .......................................................................................................... 293 Rev. 1.4 7 C8051F93x-C8051F92x 25.2.1.16-bit Timer with Auto-Reload................................................................ 293 25.2.2.8-bit Timers with Auto-Reload................................................................ 294 25.2.3.Comparator 0/SmaRTClock Capture Mode ........................................... 295 25.3.Timer 3 .......................................................................................................... 299 25.3.1.16-bit Timer with Auto-Reload................................................................ 299 25.3.2.8-bit Timers with Auto-Reload................................................................ 300 25.3.3.Comparator 1/External Oscillator Capture Mode ................................... 301 26. Programmable Counter Array ............................................................................. 305 26.1.PCA Counter/Timer ........................................................................................ 306 26.2.PCA0 Interrupt Sources.................................................................................. 307 26.3.Capture/Compare Modules ............................................................................ 308 26.3.1.Edge-triggered Capture Mode................................................................ 309 26.3.2.Software Timer (Compare) Mode........................................................... 310 26.3.3.High-Speed Output Mode ...................................................................... 311 26.3.4.Frequency Output Mode ........................................................................ 312 26.3.5. 8-Bit, 9-Bit, 10-Bit and 11-Bit Pulse Width Modulator Modes............... 313 26.3.6. 16-Bit Pulse Width Modulator Mode..................................................... 315 26.4.Watchdog Timer Mode ................................................................................... 316 26.4.1.Watchdog Timer Operation .................................................................... 316 26.4.2.Watchdog Timer Usage ......................................................................... 317 26.5.Register Descriptions for PCA0...................................................................... 318 27. C2 Interface ........................................................................................................... 324 27.1.C2 Interface Registers.................................................................................... 324 27.2.C2 Pin Sharing ............................................................................................... 327 Document Change List............................................................................................. 328 Contact Information.................................................................................................. 330 8 Rev. 1.4 C8051F93x-C8051F92x List of Figures Figure 1.1. C8051F930 Block Diagram .................................................................... 18 Figure 1.2. C8051F931 Block Diagram .................................................................... 18 Figure 1.3. C8051F920 Block Diagram .................................................................... 19 Figure 1.4. C8051F921 Block Diagram .................................................................... 19 Figure 1.5. Port I/O Functional Block Diagram ......................................................... 21 Figure 1.6. PCA Block Diagram................................................................................ 22 Figure 1.7. ADC0 Functional Block Diagram............................................................ 23 Figure 1.8. ADC0 Multiplexer Block Diagram ........................................................... 24 Figure 1.9. Comparator 0 Functional Block Diagram ............................................... 25 Figure 1.10. Comparator 1 Functional Block Diagram ............................................. 25 Figure 3.1. QFN-32 Pinout Diagram (Top View) ...................................................... 31 Figure 3.2. QFN-24 Pinout Diagram (Top View) ...................................................... 32 Figure 3.3. LQFP-32 Pinout Diagram (Top View)..................................................... 33 Figure 3.4. QFN-32 Package Marking Diagram ....................................................... 34 Figure 3.5. QFN-24 Package Marking Diagram ....................................................... 35 Figure 3.6. LQFP-32 Package Marking Diagram ..................................................... 36 Figure 3.7. QFN-32 Package Drawing ..................................................................... 37 Figure 3.8. Typical QFN-32 Landing Diagram.......................................................... 38 Figure 3.9. QFN-24 Package Drawing ..................................................................... 40 Figure 3.10. Typical QFN-24 Landing Diagram........................................................ 41 Figure 3.11. LQFP-32 Package Diagram ................................................................. 43 Figure 3.12. Typical LQFP-32 Landing Diagram ...................................................... 44 Figure 4.1. Active Mode Current (External CMOS Clock) ........................................ 48 Figure 4.2. Idle Mode Current (External CMOS Clock) ............................................ 49 Figure 4.3. Typical DC-DC Converter Efficiency (High Current, VDD/DC+ = 2 V) ... 50 Figure 4.4. Typical DC-DC Converter Efficiency (High Current, VDD/DC+ = 3 V) ... 51 Figure 4.5. Typical DC-DC Converter Efficiency (Low Current, VDD/DC+ = 2 V).... 52 Figure 4.6. Typical One-Cell Suspend Mode Current............................................... 53 Figure 4.7. Typical VOH Curves, 1.8–3.6 V ............................................................. 55 Figure 4.8. Typical VOH Curves, 0.9–1.8 V ............................................................. 56 Figure 4.9. Typical VOL Curves, 1.8–3.6 V .............................................................. 57 Figure 4.10. Typical VOL Curves, 0.9–1.8 V ............................................................ 58 Figure 5.1. ADC0 Functional Block Diagram............................................................ 67 Figure 5.2. 10-Bit ADC Track and Conversion Example Timing (BURSTEN = 0).... 70 Figure 5.3. Burst Mode Tracking Example with Repeat Count Set to 4 ................... 72 Figure 5.4. ADC0 Equivalent Input Circuits .............................................................. 73 Figure 5.5. ADC Window Compare Example: Right-Justified Single-Ended Data ... 83 Figure 5.6. ADC Window Compare Example: Left-Justified Single-Ended Data...... 83 Figure 5.7. ADC0 Multiplexer Block Diagram ........................................................... 84 Figure 5.8. Temperature Sensor Transfer Function ................................................. 86 Figure 5.9. Temperature Sensor Error with 1-Point Calibration (VREF = 1.68 V) ..... 87 Figure 5.10. Voltage Reference Functional Block Diagram...................................... 89 Figure 7.1. Comparator 0 Functional Block Diagram ............................................... 93 Rev. 1.4 9 C8051F93x-C8051F92x Figure 7.2. Comparator 1 Functional Block Diagram ............................................... 94 Figure 7.3. Comparator Hysteresis Plot ................................................................... 95 Figure 7.4. CPn Multiplexer Block Diagram............................................................ 100 Figure 8.1. CIP-51 Block Diagram.......................................................................... 103 Figure 9.1. C8051F93x-C8051F92x Memory Map ................................................. 112 Figure 9.2. Flash Program Memory Map................................................................ 113 Figure 10.1. Multiplexed Configuration Example.................................................... 118 Figure 10.2. Multiplexed to Non-Multiplexed Configuration Example..................... 119 Figure 10.3. EMIF Operating Modes ...................................................................... 120 Figure 10.4. Multiplexed 16-bit MOVX Timing........................................................ 125 Figure 10.5. Multiplexed 8-bit MOVX without Bank Select Timing ......................... 126 Figure 10.6. Multiplexed 8-bit MOVX with Bank Select Timing .............................. 127 Figure 13.1. Flash Program Memory Map.............................................................. 150 Figure 14.1. C8051F93x-C8051F92x Power Distribution....................................... 160 Figure 15.1. CRC0 Block Diagram ......................................................................... 167 Figure 15.2. Bit Reverse Register .......................................................................... 174 Figure 16.1. DC-DC Converter Block Diagram....................................................... 175 Figure 16.2. DC-DC Converter Configuration Options ........................................... 178 Figure 18.1. Reset Sources.................................................................................... 184 Figure 18.2. Power-Fail Reset Timing Diagram ..................................................... 185 Figure 18.3. Power-Fail Reset Timing Diagram ..................................................... 186 Figure 19.1. Clocking Sources Block Diagram ....................................................... 191 Figure 19.2. 25 MHz External Crystal Example...................................................... 193 Figure 20.1. SmaRTClock Block Diagram.............................................................. 200 Figure 20.2. Interpreting Oscillation Robustness (Duty Cycle) Test Results.......... 208 Figure 21.1. Port I/O Functional Block Diagram ..................................................... 216 Figure 21.2. Port I/O Cell Block Diagram ............................................................... 217 Figure 21.3. Crossbar Priority Decoder with No Pins Skipped ............................... 222 Figure 21.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 223 Figure 22.1. SMBus Block Diagram ....................................................................... 238 Figure 22.2. Typical SMBus Configuration ............................................................. 239 Figure 22.3. SMBus Transaction ............................................................................ 240 Figure 22.4. Typical SMBus SCL Generation......................................................... 243 Figure 22.5. Typical Master Write Sequence ......................................................... 252 Figure 22.6. Typical Master Read Sequence ......................................................... 253 Figure 22.7. Typical Slave Write Sequence ........................................................... 254 Figure 22.8. Typical Slave Read Sequence ........................................................... 255 Figure 23.1. UART0 Block Diagram ....................................................................... 260 Figure 23.2. UART0 Baud Rate Logic .................................................................... 261 Figure 23.3. UART Interconnect Diagram .............................................................. 262 Figure 23.4. 8-Bit UART Timing Diagram............................................................... 262 Figure 23.5. 9-Bit UART Timing Diagram............................................................... 263 Figure 23.6. UART Multi-Processor Mode Interconnect Diagram .......................... 264 Figure 24.1. SPI Block Diagram ............................................................................. 268 Figure 24.2. Multiple-Master Mode Connection Diagram ....................................... 271 10 Rev. 1.4 C8051F93x-C8051F92x Figure 24.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram 271 Figure 24.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram 271 Figure 24.5. Master Mode Data/Clock Timing ........................................................ 273 Figure 24.6. Slave Mode Data/Clock Timing (CKPHA = 0) .................................... 274 Figure 24.7. Slave Mode Data/Clock Timing (CKPHA = 1) .................................... 274 Figure 24.8. SPI Master Timing (CKPHA = 0)........................................................ 280 Figure 24.9. SPI Master Timing (CKPHA = 1)........................................................ 280 Figure 24.10. SPI Slave Timing (CKPHA = 0)........................................................ 281 Figure 24.11. SPI Slave Timing (CKPHA = 1)........................................................ 281 Figure 25.1. T0 Mode 0 Block Diagram.................................................................. 286 Figure 25.2. T0 Mode 2 Block Diagram.................................................................. 287 Figure 25.3. T0 Mode 3 Block Diagram.................................................................. 288 Figure 25.4. Timer 2 16-Bit Mode Block Diagram .................................................. 293 Figure 25.5. Timer 2 8-Bit Mode Block Diagram .................................................... 294 Figure 25.6. Timer 2 Capture Mode Block Diagram ............................................... 295 Figure 25.7. Timer 3 16-Bit Mode Block Diagram .................................................. 299 Figure 25.8. Timer 3 8-Bit Mode Block Diagram. ................................................... 300 Figure 25.9. Timer 3 Capture Mode Block Diagram ............................................... 301 Figure 26.1. PCA Block Diagram............................................................................ 305 Figure 26.2. PCA Counter/Timer Block Diagram.................................................... 306 Figure 26.3. PCA Interrupt Block Diagram ............................................................. 307 Figure 26.4. PCA Capture Mode Diagram.............................................................. 309 Figure 26.5. PCA Software Timer Mode Diagram .................................................. 310 Figure 26.6. PCA High-Speed Output Mode Diagram............................................ 311 Figure 26.7. PCA Frequency Output Mode ............................................................ 312 Figure 26.8. PCA 8-Bit PWM Mode Diagram ......................................................... 313 Figure 26.9. PCA 9, 10 and 11-Bit PWM Mode Diagram ....................................... 314 Figure 26.10. PCA 16-Bit PWM Mode.................................................................... 315 Figure 26.11. PCA Module 5 with Watchdog Timer Enabled ................................. 316 Figure 27.1. Typical C2 Pin Sharing....................................................................... 327 Rev. 1.4 11 C8051F93x-C8051F92x List of Tables Table 2.1. Product Selection Guide ......................................................................... 26 Table 3.1. Pin Definitions for the C8051F92x-C8051F93x ...................................... 27 Table 3.2. QFN-32 Package Dimensions ................................................................ 37 Table 3.3. PCB Land Pattern ................................................................................... 39 Table 3.4. QFN-24 Package Dimensions ................................................................ 40 Table 3.5. PCB Land Pattern ................................................................................... 42 Table 3.6. LQFP-32 Package Dimensions .............................................................. 43 Table 3.7. PCB Land Pattern ................................................................................... 44 Table 4.1.Absolute Maximum Ratings ..................................................................... 45 Table 4.2.Global Electrical Characteristics .............................................................. 46 Table 4.3.Port I/O DC Electrical Characteristics ...................................................... 54 Table 4.4.Reset Electrical Characteristics ............................................................... 59 Table 4.5.Power Management Electrical Specifications .......................................... 60 Table 4.6.Flash Electrical Characteristics ............................................................... 60 Table 4.7.Internal Precision Oscillator Electrical Characteristics ............................ 60 Table 4.8.Internal Low-Power Oscillator Electrical Characteristics ......................... 60 Table 4.9.ADC0 Electrical Characteristics ............................................................... 61 Table 4.10.Temperature Sensor Electrical Characteristics ..................................... 62 Table 4.11.Voltage Reference Electrical Characteristics ........................................ 62 Table 4.12.IREF0 Electrical Characteristics ............................................................ 63 Table 4.13.Comparator Electrical Characteristics ................................................... 64 Table 4.14.DC-DC Converter (DC0) Electrical Characteristics ............................... 66 Table 4.15.VREG0 Electrical Characteristics .......................................................... 66 Table 8.1. CIP-51 Instruction Set Summary .......................................................... 105 Table 10.1.AC Parameters for External Memory Interface .................................... 128 Table 11.1. Special Function Register (SFR) Memory Map (Page 0x0) ............... 129 Table 11.2. Special Function Register (SFR) Memory Map (Page 0xF) ............... 130 Table 11.3. Special Function Registers ................................................................. 131 Table 12.1. Interrupt Summary .............................................................................. 138 Table 13.1. Flash Security Summary .................................................................... 151 Table 14.1. Power Modes ...................................................................................... 159 Table 15.1. Example 16-bit CRC Outputs ............................................................. 168 Table 15.2.Example 32-bit CRC Outputs .............................................................. 170 Table 16.1. IPeak Inductor Current Limit Settings ................................................. 176 Table 19.1. Recommended XFCN Settings for Crystal Mode ............................... 193 Table 19.2. Recommended XFCN Settings for RC and C modes ......................... 194 Table 20.1.SmaRTClock Internal Registers .......................................................... 201 Table 20.2. SmaRTClock Load Capacitance Settings .......................................... 207 Table 20.3. SmaRTClock Bias Settings ................................................................ 209 Table 21.1. Port I/O Assignment for Analog Functions ......................................... 218 Table 21.2. Port I/O Assignment for Digital Functions ........................................... 220 Table 21.3. Port I/O Assignment for External Digital Event Capture Functions .... 220 Table 22.1. SMBus Clock Source Selection .......................................................... 243 Rev. 1.4 12 C8051F93x-C8051F92x Table 22.2. Minimum SDA Setup and Hold Times ................................................ 244 Table 22.3. Sources for Hardware Changes to SMB0CN ..................................... 248 Table 22.4. Hardware Address Recognition Examples (EHACK = 1) ................... 249 Table 22.5. SMBus Status Decoding With Hardware ACK Generation Disabled (EHACK = 0) ....................................................................................... 256 Table 22.6. SMBus Status Decoding With Hardware ACK Generation Enabled (EHACK = 1) ....................................................................................... 258 Table 23.1. Timer Settings for Standard Baud Rates Using The Internal 24.5 MHz Oscillator .............................................. 267 Table 23.2. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator ......................................... 267 Table 24.1. SPI Slave Timing Parameters ............................................................ 282 Table 25.1. Timer 0 Running Modes ..................................................................... 285 Table 26.1. PCA Timebase Input Options ............................................................. 306 Table 26.2. PCA0CPM and PCA0PWM Bit Settings for PCA Capture/Compare Modules .............................................................................................. 308 Table 26.3. Watchdog Timer Timeout Intervals1 ................................................... 317 13 Rev. 1.4 C8051F93x-C8051F92x List of Registers SFR Definition 5.1. ADC0CN: ADC0 Control ................................................................ 75 SFR Definition 5.2. ADC0CF: ADC0 Configuration ...................................................... 76 SFR Definition 5.3. ADC0AC: ADC0 Accumulator Configuration ................................. 77 SFR Definition 5.4. ADC0PWR: ADC0 Burst Mode Power-Up Time ............................ 78 SFR Definition 5.5. ADC0TK: ADC0 Burst Mode Track Time ....................................... 79 SFR Definition 5.6. ADC0H: ADC0 Data Word High Byte ............................................ 80 SFR Definition 5.7. ADC0L: ADC0 Data Word Low Byte .............................................. 80 SFR Definition 5.8. ADC0GTH: ADC0 Greater-Than High Byte ................................... 81 SFR Definition 5.9. ADC0GTL: ADC0 Greater-Than Low Byte .................................... 81 SFR Definition 5.10. ADC0LTH: ADC0 Less-Than High Byte ...................................... 82 SFR Definition 5.11. ADC0LTL: ADC0 Less-Than Low Byte ........................................ 82 SFR Definition 5.12. ADC0MX: ADC0 Input Channel Select ........................................ 85 SFR Definition 5.13. TOFFH: ADC0 Data Word High Byte .......................................... 88 SFR Definition 5.14. TOFFL: ADC0 Data Word Low Byte ............................................ 88 SFR Definition 5.15. REF0CN: Voltage Reference Control .......................................... 91 SFR Definition 6.1. IREF0CN: Current Reference Control ........................................... 92 SFR Definition 7.1. CPT0CN: Comparator 0 Control .................................................... 96 SFR Definition 7.2. CPT0MD: Comparator 0 Mode Selection ...................................... 97 SFR Definition 7.3. CPT1CN: Comparator 1 Control .................................................... 98 SFR Definition 7.4. CPT1MD: Comparator 1 Mode Selection ...................................... 99 SFR Definition 7.5. CPT0MX: Comparator0 Input Channel Select ............................. 101 SFR Definition 7.6. CPT1MX: Comparator1 Input Channel Select ............................. 102 SFR Definition 8.1. DPL: Data Pointer Low Byte ........................................................ 109 SFR Definition 8.2. DPH: Data Pointer High Byte ....................................................... 109 SFR Definition 8.3. SP: Stack Pointer ......................................................................... 110 SFR Definition 8.4. ACC: Accumulator ....................................................................... 110 SFR Definition 8.5. B: B Register ................................................................................ 110 SFR Definition 8.6. PSW: Program Status Word ........................................................ 111 SFR Definition 10.1. EMI0CN: External Memory Interface Control ............................ 122 SFR Definition 10.2. EMI0CF: External Memory Configuration .................................. 123 SFR Definition 10.3. EMI0TC: External Memory Timing Control ................................ 124 SFR Definition 11.1. SFR Page: SFR Page ................................................................ 131 SFR Definition 12.1. IE: Interrupt Enable .................................................................... 140 SFR Definition 12.2. IP: Interrupt Priority .................................................................... 141 SFR Definition 12.3. EIE1: Extended Interrupt Enable 1 ............................................ 142 SFR Definition 12.4. EIP1: Extended Interrupt Priority 1 ............................................ 143 SFR Definition 12.5. EIE2: Extended Interrupt Enable 2 ............................................ 144 SFR Definition 12.6. EIP2: Extended Interrupt Priority 2 ............................................ 145 SFR Definition 12.7. IT01CF: INT0/INT1 Configuration .............................................. 147 SFR Definition 13.1. PSCTL: Program Store R/W Control ......................................... 156 SFR Definition 13.2. FLKEY: Flash Lock and Key ...................................................... 157 SFR Definition 13.3. FLSCL: Flash Scale ................................................................... 158 SFR Definition 13.4. FLWR: Flash Write Only ............................................................ 158 Rev. 1.4 14 C8051F93x-C8051F92x SFR Definition 14.1. PMU0CF: Power Management Unit Configuration1,2 ................ 165 SFR Definition 14.2. PCON: Power Management Control Register ........................... 166 SFR Definition 15.1. CRC0CN: CRC0 Control ........................................................... 171 SFR Definition 15.2. CRC0IN: CRC0 Data Input ........................................................ 172 SFR Definition 15.3. CRC0DAT: CRC0 Data Output .................................................. 172 SFR Definition 15.4. CRC0AUTO: CRC0 Automatic Control ...................................... 173 SFR Definition 15.5. CRC0CNT: CRC0 Automatic Flash Sector Count ..................... 173 SFR Definition 15.6. CRC0FLIP: CRC0 Bit Flip .......................................................... 174 SFR Definition 16.1. DC0CN: DC-DC Converter Control ........................................... 181 SFR Definition 16.2. DC0CF: DC-DC Converter Configuration .................................. 182 SFR Definition 17.1. REG0CN: Voltage Regulator Control ........................................ 183 SFR Definition 18.1. VDM0CN: VDD/DC+ Supply Monitor Control ............................ 187 SFR Definition 18.2. RSTSRC: Reset Source ............................................................ 190 SFR Definition 19.1. CLKSEL: Clock Select ............................................................... 197 SFR Definition 19.2. OSCICN: Internal Oscillator Control .......................................... 198 SFR Definition 19.3. OSCICL: Internal Oscillator Calibration ..................................... 198 SFR Definition 19.4. OSCXCN: External Oscillator Control ........................................ 199 SFR Definition 20.1. RTC0KEY: SmaRTClock Lock and Key .................................... 204 SFR Definition 20.2. RTC0ADR: SmaRTClock Address ............................................ 205 SFR Definition 20.3. RTC0DAT: SmaRTClock Data .................................................. 205 Internal Register Definition 20.4. RTC0CN: SmaRTClock Control ............................. 212 Internal Register Definition 20.5. RTC0XCN: SmaRTClock Oscillator Control ........... 213 Internal Register Definition 20.6. RTC0XCF: SmaRTClock Oscillator Configuration . 214 Internal Register Definition 20.7. RTC0PIN: SmaRTClock Pin Configuration ............ 214 Internal Register Definition 20.8. CAPTUREn: SmaRTClock Timer Capture ............. 215 Internal Register Definition 20.9. ALARMn: SmaRTClock Alarm Programmed Value 215 SFR Definition 21.1. XBR0: Port I/O Crossbar Register 0 .......................................... 224 SFR Definition 21.2. XBR1: Port I/O Crossbar Register 1 .......................................... 225 SFR Definition 21.3. XBR2: Port I/O Crossbar Register 2 .......................................... 226 SFR Definition 21.4. P0MASK: Port0 Mask Register .................................................. 227 SFR Definition 21.5. P0MAT: Port0 Match Register ................................................... 227 SFR Definition 21.6. P1MASK: Port1 Mask Register .................................................. 228 SFR Definition 21.7. P1MAT: Port1 Match Register ................................................... 228 SFR Definition 21.8. P0: Port0 .................................................................................... 230 SFR Definition 21.9. P0SKIP: Port0 Skip .................................................................... 230 SFR Definition 21.10. P0MDIN: Port0 Input Mode ...................................................... 231 SFR Definition 21.11. P0MDOUT: Port0 Output Mode ............................................... 231 SFR Definition 21.12. P0DRV: Port0 Drive Strength .................................................. 232 SFR Definition 21.13. P1: Port1 .................................................................................. 233 SFR Definition 21.14. P1SKIP: Port1 Skip .................................................................. 233 SFR Definition 21.15. P1MDIN: Port1 Input Mode ...................................................... 234 SFR Definition 21.16. P1MDOUT: Port1 Output Mode ............................................... 234 SFR Definition 21.17. P1DRV: Port1 Drive Strength .................................................. 235 SFR Definition 21.18. P2: Port2 .................................................................................. 235 SFR Definition 21.19. P2SKIP: Port2 Skip .................................................................. 236 15 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.20. P2MDIN: Port2 Input Mode ...................................................... 236 SFR Definition 21.21. P2MDOUT: Port2 Output Mode ............................................... 237 SFR Definition 21.22. P2DRV: Port2 Drive Strength .................................................. 237 SFR Definition 22.1. SMB0CF: SMBus Clock/Configuration ...................................... 245 SFR Definition 22.2. SMB0CN: SMBus Control .......................................................... 247 SFR Definition 22.3. SMB0ADR: SMBus Slave Address ............................................ 250 SFR Definition 22.4. SMB0ADM: SMBus Slave Address Mask .................................. 250 SFR Definition 22.5. SMB0DAT: SMBus Data ............................................................ 251 SFR Definition 23.1. SCON0: Serial Port 0 Control .................................................... 265 SFR Definition 23.2. SBUF0: Serial (UART0) Port Data Buffer .................................. 266 SFR Definition 24.1. SPInCFG: SPI Configuration ..................................................... 276 SFR Definition 24.2. SPInCN: SPI Control ................................................................. 277 SFR Definition 24.3. SPInCKR: SPI Clock Rate ......................................................... 278 SFR Definition 24.4. SPInDAT: SPI Data ................................................................... 279 SFR Definition 25.1. CKCON: Clock Control .............................................................. 284 SFR Definition 25.2. TCON: Timer Control ................................................................. 289 SFR Definition 25.3. TMOD: Timer Mode ................................................................... 290 SFR Definition 25.4. TL0: Timer 0 Low Byte ............................................................... 291 SFR Definition 25.5. TL1: Timer 1 Low Byte ............................................................... 291 SFR Definition 25.6. TH0: Timer 0 High Byte ............................................................. 292 SFR Definition 25.7. TH1: Timer 1 High Byte ............................................................. 292 SFR Definition 25.8. TMR2CN: Timer 2 Control ......................................................... 296 SFR Definition 25.9. TMR2RLL: Timer 2 Reload Register Low Byte .......................... 297 SFR Definition 25.10. TMR2RLH: Timer 2 Reload Register High Byte ...................... 297 SFR Definition 25.11. TMR2L: Timer 2 Low Byte ....................................................... 298 SFR Definition 25.12. TMR2H Timer 2 High Byte ....................................................... 298 SFR Definition 25.13. TMR3CN: Timer 3 Control ....................................................... 302 SFR Definition 25.14. TMR3RLL: Timer 3 Reload Register Low Byte ........................ 303 SFR Definition 25.15. TMR3RLH: Timer 3 Reload Register High Byte ...................... 303 SFR Definition 25.16. TMR3L: Timer 3 Low Byte ....................................................... 304 SFR Definition 25.17. TMR3H Timer 3 High Byte ....................................................... 304 SFR Definition 26.1. PCA0CN: PCA Control .............................................................. 318 SFR Definition 26.2. PCA0MD: PCA Mode ................................................................ 319 SFR Definition 26.3. PCA0PWM: PCA PWM Configuration ....................................... 320 SFR Definition 26.4. PCA0CPMn: PCA Capture/Compare Mode .............................. 321 SFR Definition 26.5. PCA0L: PCA Counter/Timer Low Byte ...................................... 322 SFR Definition 26.6. PCA0H: PCA Counter/Timer High Byte ..................................... 322 SFR Definition 26.7. PCA0CPLn: PCA Capture Module Low Byte ............................. 323 SFR Definition 26.8. PCA0CPHn: PCA Capture Module High Byte ........................... 323 C2 Register Definition 27.1. C2ADD: C2 Address ...................................................... 324 C2 Register Definition 27.2. DEVICEID: C2 Device ID ............................................... 325 C2 Register Definition 27.3. REVID: C2 Revision ID .................................................. 325 C2 Register Definition 27.4. FPCTL: C2 Flash Programming Control ........................ 326 C2 Register Definition 27.5. FPDAT: C2 Flash Programming Data ............................ 326 Rev. 1.4 16 C8051F93x-C8051F92x 1. System Overview C8051F93x-C8051F92x devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are listed below. Refer to Table 2.1 for specific product feature selection and part ordering numbers. • • • • • • • • • • • • • • Single/Dual Battery operation with on-chip dc-dc boost converter. High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS) In-system, full-speed, non-intrusive debug interface (on-chip) True 10-bit 300 ksps 23-channel single-ended ADC with analog multiplexer 6-Bit Programmable Current Reference Precision programmable 24.5 MHz internal oscillator with spread spectrum technology. 64 kB or 32 kB of on-chip Flash memory 4352 bytes of on-chip RAM SMBus/I2C, Enhanced UART, and two Enhanced SPI serial interfaces implemented in hardware Four general-purpose 16-bit timers Programmable Counter/Timer Array (PCA) with six capture/compare modules and Watchdog Timer function On-chip Power-On Reset, VDD Monitor, and Temperature Sensor Two On-chip Voltage Comparators with 23 Touch Sense inputs. 24 or 16 Port I/O (5 V tolerant) With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F93xC8051F92x devices are truly stand-alone System-on-a-Chip solutions. The Flash memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually shut down any or all peripherals for power savings. The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the production MCU installed in the final application. This debug logic supports inspection and modification of memory and registers, setting breakpoints, single stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying package pins. Each device is specified for 0.9 to 1.8 V or 1.8 to 3.6 V operation over the industrial temperature range (–40 to +85 °C). The Port I/O and RST pins are tolerant of input signals up to 5 V. The C8051F930/20 are available in 32-pin QFN or LQFP packages and the C8051F931/21 are available in a 24-pin QFN package. Both package options are lead-free and RoHS compliant. See Table 2.1 for ordering information. Block diagrams are included in Figure 1.1 through Figure 1.4. Rev. 1.4 17 C8051F93x-C8051F92x Wake Reset C2CK/RST Debug / Programming Hardware Power Net UART 256 Byte SRAM Timers 0, 1, 2, 3 4096 Byte XRAM VREG Analog Power GND/DC- DCEN VBAT DC/DC Converter SPI 0,1 Crossbar Control SFR Bus Low Power 20 MHz Oscillator GND XTAL2 XTAL3 Port 0 Drivers P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVSTR P0.7/IREF0 IREF0 Internal External VREF VREF VDD VREF Temp Sensor A M U X 10-bit 300ksps ADC SmaRTClock Oscillator XTAL4 Analog Peripherals 6-bit IREF External Oscillator Circuit XTAL1 Port 2 Drivers P2.0/A8 P2.1/A9 P2.2/A10 P2.3/A11 P2.4/ALE P2.5/RD P2.6/WR P2.7/C2D SMBus SYSCLK Precision 24.5 MHz Oscillator Port 1 Drivers P1.0/AD0 P1.1/AD1 P1.2/AD2 P1.3/AD3 P1.4/AD4 P1.5/AD5 P1.6/AD6 P1.7/AD7 Priority Crossbar Decoder PCA/ WDT CRC Engine Digital Power Port 0 Drivers P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVSTR P0.7/IREF0 Digital Peripherals 64 kB ISP Flash Program Memory C2D VDD/DC+ Port I/O Configuration CIP-51 8051 Controller Core Power On Reset/PMU GND CP0, CP0A System Clock Configuration CP1, CP1A + - + - Comparators Figure 1.1. C8051F930 Block Diagram Wake Reset C2CK/RST Debug / Programming Hardware Power Net Analog Power GND/DC- DCEN UART 256 Byte SRAM Timers 0, 1, 2, 3 4096 Byte XRAM VBAT GND XTAL1 XTAL2 XTAL3 XTAL4 VREG Digital Power Priority Crossbar Decoder PCA/ WDT CRC Engine SMBus SPI 0,1 SYSCLK Precision 24.5 MHz Oscillator DC/DC Converter Digital Peripherals 64 kB ISP Flash Program Memory C2D VDD/DC+ Port I/O Configuration CIP-51 8051 Controller Core Power On Reset/PMU Low Power 20 MHz Oscillator External Oscillator Circuit SmaRTClock Oscillator Crossbar Control SFR Bus Analog Peripherals 6-bit IREF IREF0 Internal External VREF VREF Port 2 Drivers A M U X 10-bit 300ksps ADC VDD VREF Temp Sensor GND CP0, CP0A System Clock Configuration CP1, CP1A + - + - Comparators Figure 1.2. C8051F931 Block Diagram 18 Port 1 Drivers P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 Rev. 1.4 P2.7/C2D C8051F93x-C8051F92x Wake Reset C2CK/RST Debug / Programming Hardware Power Net UART 256 Byte SRAM Timers 0, 1, 2, 3 4096 Byte XRAM VREG Analog Power GND/DC- DCEN VBAT DC/DC Converter SPI 0,1 Crossbar Control SFR Bus Low Power 20 MHz Oscillator GND XTAL2 XTAL3 Port 0 Drivers P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVSTR P0.7/IREF0 IREF0 Internal External VREF VREF VDD VREF Temp Sensor A M U X 10-bit 300ksps ADC SmaRTClock Oscillator XTAL4 Analog Peripherals 6-bit IREF External Oscillator Circuit XTAL1 Port 2 Drivers P2.0/A8 P2.1/A9 P2.2/A10 P2.3/A11 P2.4/ALE P2.5/RD P2.6/WR P2.7/C2D SMBus SYSCLK Precision 24.5 MHz Oscillator Port 1 Drivers P1.0/AD0 P1.1/AD1 P1.2/AD2 P1.3/AD3 P1.4/AD4 P1.5/AD5 P1.6/AD6 P1.7/AD7 Priority Crossbar Decoder PCA/ WDT CRC Engine Digital Power Port 0 Drivers P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVSTR P0.7/IREF0 Digital Peripherals 32 kB ISP Flash Program Memory C2D VDD/DC+ Port I/O Configuration CIP-51 8051 Controller Core Power On Reset/PMU GND CP0, CP0A System Clock Configuration CP1, CP1A + - + - Comparators Figure 1.3. C8051F920 Block Diagram Wake Reset C2CK/RST Debug / Programming Hardware Power Net Analog Power GND/DC- DCEN UART 256 Byte SRAM Timers 0, 1, 2, 3 4096 Byte XRAM VBAT GND XTAL1 XTAL2 XTAL3 XTAL4 VREG Digital Power Priority Crossbar Decoder PCA/ WDT CRC Engine SMBus SPI 0,1 SYSCLK Precision 24.5 MHz Oscillator DC/DC Converter Digital Peripherals 32 kB ISP Flash Program Memory C2D VDD/DC+ Port I/O Configuration CIP-51 8051 Controller Core Power On Reset/PMU Low Power 20 MHz Oscillator External Oscillator Circuit SmaRTClock Oscillator Crossbar Control SFR Bus Analog Peripherals 6-bit IREF IREF0 Internal External VREF VREF Port 2 Drivers A M U X 10-bit 300ksps ADC VDD VREF Temp Sensor P2.7/C2D GND CP0, CP0A System Clock Configuration Port 1 Drivers P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 CP1, CP1A + - + - Comparators Figure 1.4. C8051F921 Block Diagram Rev. 1.4 19 C8051F93x-C8051F92x 1.1. CIP-51™ Microcontroller Core 1.1.1. Fully 8051 Compatible The C8051F93x-C8051F92x family 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 CIP-51 core offers all the peripherals included with a standard 8052. 1.1.2. Improved Throughput The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute 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. 1.1.3. Additional Features The C8051F93x-C8051F92x SoC family includes several key enhancements to the CIP-51 core and peripherals to improve performance and ease of use in end applications. The extended interrupt handler provides multiple interrupt sources into the CIP-51 allowing numerous analog and digital peripherals to interrupt the controller. An interrupt driven system requires less intervention by the MCU, giving it more effective throughput. The extra interrupt sources are very useful when building multi-tasking, real-time systems. Eight reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor (forces reset when power supply voltage drops below safe levels), a Watchdog Timer, a Missing Clock Detector, SmaRTClock oscillator fail or alarm, a voltage level detection from Comparator0, a forced software reset, an external reset pin, and an illegal Flash access protection circuit. Each reset source except for the POR, Reset Input Pin, or Flash error may be disabled by the user in software. The WDT may be permanently disabled in software after a power-on reset during MCU initialization. The internal oscillator factory calibrated to 24.5 MHz and is accurate to ±2% over the full temperature and supply range. The internal oscillator period can also be adjusted by user firmware. An additional 20 MHz low power oscillator is also available which facilitates low-power operation. An external oscillator drive circuit is included, allowing an external crystal, ceramic resonator, capacitor, RC, or CMOS clock source to generate the system clock. If desired, the system clock source may be switched on-the-fly between both internal and external oscillator circuits. An external oscillator can also be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) source, while periodically switching to the fast (up to 25 MHz) internal oscillator as needed. 20 Rev. 1.4 C8051F93x-C8051F92x 1.2. Port Input/Output Digital and analog resources are available through 24 I/O pins (C8051F930/20) or 16 I/O pins (C8051F931/21). Port pins are organized as three byte-wide ports. Port pins P0.0–P2.6 can be defined as digital or analog I/O. Digital I/O pins can be assigned to one of the internal digital resources or used as general purpose I/O (GPIO). Analog I/O pins are used by the internal analog resources. P2.7 can be used as GPIO and is shared with the C2 Interface Data signal (C2D). See Section “27. C2 Interface” on page 324 for more details. The designer has complete control over which digital and analog functions are assigned to individual Port pins, limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. See Section “21.3. Priority Crossbar Decoder” on page 221 for more information on the Crossbar. All Port I/Os are 5 V tolerant when used as digital inputs or open-drain outputs. For Port I/Os configured as push-pull outputs, current is sourced from the VDD/DC+ supply. Port I/Os used for analog functions can operate up to the VDD/DC+ supply voltage. See Section “21.1. Port I/O Modes of Operation” on page 217 for more information on Port I/O operating modes and the electrical specifications chapter for detailed electrical specifications. XBR0, XBR1, XBR2, PnSKIP Registers Port Match P0MASK, P0MAT P1MASK, P1MAT External Interrupts EX0 and EX1 Priority Decoder Highest Priority UART 4 (Internal Digital Signals) SPI0 SPI1 P0.0 2 SMBus CP0 CP1 Outputs Digital Crossbar 8 4 P1.0 8 P1 I/O Cells 7 T0, T1 P0 I/O Cells P0.7 SYSCLK PCA Lowest Priority PnMDOUT, PnMDIN Registers 2 P1.7 2 8 (Port Latches) P0 P2.0 8 (P0.0-P0.7) P2 I/O Cell 8 P1 (P1.0-P1.7) To EMIF 8 P2 (P2.0-P2.7) P1.6 To Analog Peripherals (ADC0, CP0, and CP1 inputs, VREF, IREF0, AGND) P2.6 P2.7 P1.7–2.6 only available on 32-pin devices P2.7 is available on all devices Figure 1.5. Port I/O Functional Block Diagram Rev. 1.4 21 C8051F93x-C8051F92x 1.3. Serial Ports The C8051F93x-C8051F92x Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud rate configuration, and two Enhanced SPI interfaces. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention. 1.4. Programmable Counter Array An on-chip Programmable Counter/Timer Array (PCA) is included in addition to the four 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 PCA clock is derived from one of six sources: the system clock divided by 12, the system clock divided by 4, Timer 0 overflows, an External Clock Input (ECI), the system clock, or the external oscillator clock source divided by 8. Each capture/compare module can be configured to operate in a variety of modes: edge-triggered capture, software timer, high-speed output, pulse width modulator (8, 9, 10, 11, or 16-bit), or frequency output. Additionally, Capture/Compare Module 5 offers watchdog timer (WDT) capabilities. Following a system reset, Module 5 is configured and enabled in WDT mode. The PCA Capture/Compare Module I/O and External Clock Input may be routed to Port I/O via the Digital Crossbar. SYSCLK /12 SYSCLK /4 Timer 0 Overflow ECI PCA CLOCK MUX 16 -Bit Counter/Timer SYSCLK External Clock /8 Capture/ Compare Module 0 Capture/ Compare Module 1 Capture/ Compare Module 2 Capture/ Compare Module 3 Figure 1.6. PCA Block Diagram 22 Rev. 1.4 Capture/ Compare Module5 / WDT CEX5 Port I/O CEX4 CEX3 CEX2 CEX1 CEX0 ECI Crossbar Capture/ Compare Module 4 C8051F93x-C8051F92x 1.5. 10-Bit SAR ADC with 16-bit Auto-Averaging Accumulator and Autonomous Low Power Burst Mode C8051F93x-C8051F92x devices have a 300 ksps, 10-bit successive-approximation-register (SAR) ADC with integrated track-and-hold and programmable window detector. ADC0 also has an autonomous low power Burst Mode which can automatically enable ADC0, capture and accumulate samples, then place ADC0 in a low power shutdown mode without CPU intervention. It also has a 16-bit accumulator that can automatically average the ADC results, providing an effective 11, 12, or 13 bit ADC result without any additional CPU intervention. The ADC can sample the voltage at any of the GPIO pins (with the exception of P2.7) and has an on-chip attenuator that allows it to measure voltages up to twice the voltage reference. Additional ADC inputs include an on-chip temperature sensor, the VDD/DC+ supply voltage, the VBAT supply voltage, and the internal digital supply voltage. AD0CM0 AD0CM1 AD0CM2 AD0WINT AD0INT AD0BUSY BURSTEN AD0EN ADC0CN VDD Start Conversion ADC0TK Burst Mode Logic ADC0PWR CNVSTR Input REF 16-Bit Accumulator SYSCLK AD0TM AMP0GN AD08BE AD0SC0 AD0SC1 AD0SC2 AD0SC3 100 ADC0L ADC ADC0CF AD0BUSY (W) Timer 0 Overflow Timer 2 Overflow Timer 3 Overflow ADC0H AIN+ AD0SC4 From AMUX0 10-Bit SAR 000 001 010 011 AD0WINT 32 ADC0LTH ADC0LTL Window Compare Logic ADC0GTH ADC0GTL Figure 1.7. ADC0 Functional Block Diagram Rev. 1.4 23 C8051F93x-C8051F92x AD0MX4 AD0MX3 AD0MX2 AD0MX1 AM0MX0 ADC0MX P0.0 Programmable Attenuator AIN+ P2.6* AMUX ADC0 Temp Sensor Gain = 0. 5 or 1 VBAT Digital Supply VDD/DC+ *P1.7-P2. 6 only available as inputs on 32- pin packages Figure 1.8. ADC0 Multiplexer Block Diagram 1.6. Programmable Current Reference (IREF0) C8051F93x-C8051F92x devices include an on-chip programmable current reference (source or sink) with two output current settings: low power mode and high current mode. The maximum current output in low power mode is 63 µA (1 µA steps) and the maximum current output in high current mode is 504 µA (8 µA steps). 1.7. Comparators C8051F93x-C8051F92x devices include two on-chip programmable voltage comparators: Comparator 0 (CPT0) which is shown in Figure 1.9; Comparator 1 (CPT1) which is shown in Figure 1.10. The two comparators operate identically but may differ in their ability to be used as reset or wake-up sources. See Section “18. Reset Sources” on page 184 and the Section “14. Power Management” on page 159 for details on reset sources and low power mode wake-up sources, respectively. The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an asynchronous “raw” output (CP0A, CP1A). The asynchronous CP0A signal is available even when the system clock is not active. This allows the Comparator to operate and generate an output when the device is in some low power modes. The comparator inputs may be connected to Port I/O pins or to other internal signals. Port pins may also be used to directly sense capacitive touch switches. 24 Rev. 1.4 CPT0CN C8051F93x-C8051F92x CP0EN CP0OUT CP0RIF CP0FIF VDD CP0HYP1 CP0HYP0 CP0HYN1 CP0 Interrupt CP0HYN0 CPT0MD Analog Input Multiplexer CP0FIE CP0RIE CP0MD1 CP0MD0 Px.x CP0 Rising-edge CP0 + CP0 Falling-edge Interrupt Logic Px.x CP0 + SET D - CLR Q D Q SET CLR Q Q Px.x Crossbar (SYNCHRONIZER) GND CP0 - CP0A (ASYNCHRONOUS) Reset Decision Tree Px.x Figure 1.9. Comparator 0 Functional Block Diagram CPT0CN CP1EN CP1OUT CP1RIF VDD CP1FIF CP1HYP1 CP1 Interrupt CP1HYP0 CP1HYN1 CP1HYN0 CPT0MD Analog Input Multiplexer CP1FIE CP1RIE CP1MD1 CP1MD0 Px.x CP1 Rising-edge CP1 + CP1 Falling-edge Interrupt Logic Px.x CP1 + D - SET CLR Q Q D SET CLR Q Q Px.x Crossbar (SYNCHRONIZER) CP1 - GND (ASYNCHRONOUS) Px.x CP1A Reset Decision Tree Figure 1.10. Comparator 1 Functional Block Diagram Rev. 1.4 25 C8051F93x-C8051F92x 2. Ordering Information UART Enhanced SPI Timers (16-bit) Programmable Counter Array 10-bit 300ksps ADC Programmable Current Reference Internal Voltage Reference Temperature Sensor Analog Comparators Lead-free (RoHS Compliant) Package 1 2 4  24     2  QFN-32 C8051F930-G-GQ 25 64 4352  1 1 2 4  24     2  LQFP-32 C8051F931-G-GM 25 64 4352  1 1 2 4  16     2  QFN-24 C8051F920-G-GM 25 32 4352  1 1 2 4  24     2  QFN-32 C8051F920-G-GQ 25 32 4352  1 1 2 4  24     2  LQFP-32 C8051F921-G-GM 25 32 4352  1 1 2 4  16     2  QFN-24 Digital Port I/Os SMBus/I2C 1 RAM (bytes)  Flash Memory (kB) 25 64 4352 MIPS (Peak) C8051F930-G-GM Ordering Part Number SmaRTClock Real Time Clock Table 2.1. Product Selection Guide *Note: Starting with silicon revision F, the ordering part numbers have been updated to include the silicon revision and use this format: "C8051F930-F-GM". Package marking diagrams are included as Figure 3.4, Figure 3.5, and Figure 3.6 to help identify the silicon revision. Rev. 1.4 26 C8051F93x-C8051F92x 3. Pinout and Package Definitions Table 3.1. Pin Definitions for the C8051F92x-C8051F93x Name Pin Numbers ‘F920/30 ‘F921/31 Type Description VBAT 5 5 P In Battery Supply Voltage. Must be 0.9 to 1.8 V in single-cell battery mode and 1.8 to 3.6 V in dual-cell battery mode. VDD / 3 3 P In Power Supply Voltage. Must be 1.8 to 3.6 V. This supply voltage is not required in low power sleep mode. This voltage must always be > VBAT. DC+ DC– / 1 1 GND P Out Positive output of the dc-dc converter. In single-cell battery mode, a 1 µF ceramic capacitor is required between DC+ and DC–. This pin can supply power to external devices when operating in single-cell battery mode. P In DC-DC converter return current path. In single-cell battery mode, this pin is typically not connected to ground. G In dual-cell battery mode, this pin must be connected directly to ground. Required Ground. GND 2 2 G DCEN 4 4 P In G RST/ 6 6 C2CK P2.7/ 7 7 C2D DC-DC Enable Pin. In single-cell battery mode, this pin must be connected to VBAT through a 0.68 µH inductor. In dual-cell battery mode, this pin must be connected directly to ground. D I/O Device Reset. Open-drain output of internal POR or VDD monitor. An external source can initiate a system reset by driving this pin low for at least 15 µs. A 1 kΩ to 5 kΩ pullup to VDD is recommended. See Reset Sources Section for a complete description. D I/O Clock signal for the C2 Debug Interface. D I/O Port 2.7. This pin can only be used as GPIO. The Crossbar cannot route signals to this pin and it cannot be configured as an analog input. See Port I/O Section for a complete description. D I/O Bi-directional data signal for the C2 Debug Interface. XTAL3 10 9 A In SmaRTClock Oscillator Crystal Input. See Section 20 for a complete description. XTAL4 9 8 A Out SmaRTClock Oscillator Crystal Output. See Section 20 for a complete description. *Note: Available only on the C8051F920/30. Rev. 1.4 27 C8051F93x-C8051F92x Table 3.1. Pin Definitions for the C8051F92x-C8051F93x (Continued) Name P0.0 Pin Numbers ‘F920/30 ‘F921/31 32 24 VREF P0.1 31 23 22 XTAL1 P0.3 21 XTAL2 A Out A In 28 20 TX P0.5 19 RX P0.6 18 CNVSTR P0.7 IREF0 17 UART RX Pin. See Port I/O Section. D I/O or Port 0.6. See Port I/O Section for a complete description. A In D In 25 UART TX Pin. See Port I/O Section. D I/O or Port 0.5. See Port I/O Section for a complete description. A In D In 26 External Clock Output. This pin is the excitation driver for an external crystal or resonator. External Clock Input. This pin is the external clock input in external CMOS clock mode. External Clock Input. This pin is the external clock input in capacitor or RC oscillator configurations. See Oscillator Section for complete details. D I/O or Port 0.4. See Port I/O Section for a complete description. A In D Out 27 External Clock Input. This pin is the external oscillator return for a crystal or resonator. See Oscillator Section. D I/O or Port 0.3. See Port I/O Section for a complete description. A In D In P0.4 Optional Analog Ground. See ADC0 Section for details. D I/O or Port 0.2. See Port I/O Section for a complete description. A In A In 29 External VREF Input. Internal VREF Output. External VREF decoupling capacitors are recommended. See ADC0 Section for details. D I/O or Port 0.1. See Port I/O Section for a complete description. A In G 30 Description D I/O or Port 0.0. See Port I/O Section for a complete description. A In A In A Out AGND P0.2 Type External Convert Start Input for ADC0. See ADC0 section for a complete description. D I/O or Port 0.7. See Port I/O Section for a complete description. A In A Out IREF0 Output. See IREF Section for complete description. *Note: Available only on the C8051F920/30. 28 Rev. 1.4 C8051F93x-C8051F92x Table 3.1. Pin Definitions for the C8051F92x-C8051F93x (Continued) Name P1.0 Pin Numbers ‘F920/30 ‘F921/31 24 16 AD0* P1.1 23 15 14 AD2* P1.3 13 AD3* P1.4 12 AD4* P1.5 11 AD5* Address/Data 3. D I/O or Port 1.4. See Port I/O Section for a complete description. A In D I/O 19 Address/Data 2. D I/O or Port 1.3. See Port I/O Section for a complete description. A In May also be used as NSS for SPI1. D I/O 20 Address/Data 1. D I/O or Port 1.2. See Port I/O Section for a complete description. A In May also be used as MOSI for SPI1. D I/O 21 Address/Data 0. D I/O or Port 1.1. See Port I/O Section for a complete description. A In May also be used as MISO for SPI1. D I/O 22 Description D I/O or Port 1.0. See Port I/O Section for a complete description. A In May also be used as SCK for SPI1. D I/O AD1* P1.2 Type Address/Data 4. D I/O or Port 1.5. See Port I/O Section for a complete description. A In D I/O Address/Data 5. P1.6 18 AD6* P1.7* AD8* D I/O or Port 1.6. See Port I/O Section for a complete description. A In D I/O 17 AD7* P2.0* 10 D I/O or Port 1.7. See Port I/O Section for a complete description. A In D I/O 16 Address/Data 6. Address/Data 7. D I/O or Port 2.0. See Port I/O Section for a complete description. A In D I/O Address/Data 8. *Note: Available only on the C8051F920/30. Rev. 1.4 29 C8051F93x-C8051F92x Table 3.1. Pin Definitions for the C8051F92x-C8051F93x (Continued) Name P2.1* Pin Numbers ‘F920/30 ‘F921/31 15 AD9* P2.2* 14 AD11* P2.4* ALE* P2.5* RD* P2.6* WR* Address Latch Enable. D I/O or Port 2.5. See Port I/O Section for a complete description. A In DO 8 Address/Data 11. D I/O or Port 2.4. See Port I/O Section for a complete description. A In DO 11 Address/Data 10. D I/O or Port 2.3. See Port I/O Section for a complete description. A In D I/O 12 Address/Data 9. D I/O or Port 2.2. See Port I/O Section for a complete description. A In D I/O 13 Description D I/O or Port 2.1. See Port I/O Section for a complete description. A In D I/O AD10* P2.3* Type Read Strobe. D I/O or Port 2.6. See Port I/O Section for a complete description. A In DO Write Strobe. *Note: Available only on the C8051F920/30. 30 Rev. 1.4 P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVSTR P0.7/IREF0 32 31 30 29 28 27 26 25 C8051F93x-C8051F92x GND/DC- 1 24 P1.0/AD0 GND 2 23 P1.1/AD1 VDD/DC+ 3 22 P1.2/AD2 DCEN 4 21 P1.3/AD3 VBAT 5 20 P1.4/AD4 RST/C2CK 6 19 P1.5/AD5 P2.7/C2D 7 18 P1.6/AD6 P2.6/WR 8 17 P1.7/AD7 C8051F930/20-GM Top View 14 15 16 P2.1/A9 P2.0/A8 12 P2.4/ALE P2.2/A10 11 P2.5/RD 13 10 XTAL3 P2.3/A11 9 XTAL4 GND (optional) Figure 3.1. QFN-32 Pinout Diagram (Top View) Rev. 1.4 31 P0.0/VREF P0.1/AGND P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX 24 23 22 21 20 19 C8051F93x-C8051F92x GND/DC- 1 18 P0.6/CNVSTR GND 2 17 P0.7/IREF0 VDD/DC+ 3 16 P1.0 DCEN 4 15 P1.1 VBAT 5 14 P1.2 RST/C2CK 6 13 P1.3 C8051F931/21-GM Top View 7 8 9 10 11 12 P2.7/C2D XTAL4 XTAL3 P1.6 P1.5 P1.4 GND (optional) Figure 3.2. QFN-24 Pinout Diagram (Top View) 32 Rev. 1.4 P0.0 / VREF P0.1 / AGND P0.2 / XTAL1 P0.3 / XTAL2 P0.4 / TX P0.5 / RX P0.6 / CNVSTR P0.7 / IREF0 32 31 30 29 28 27 26 25 C8051F93x-C8051F92x GND / DC- 1 24 P1.0 / AD0 GND 2 23 P1.1 / AD1 VDD / DC+ 3 22 P1.2 / AD2 DCEN 4 21 P1.3 / AD3 VBAT 5 20 P1.4 / AD4 RST / C2CK 6 19 P1.5 / AD5 P2.7 / C2D 7 18 P1.6 / AD6 P2.6 / WR 8 17 P1.7 / AD7 14 15 16 P2.1 / A9 P2.0 / A8 12 P2.4 / ALE P2.2 / A10 11 P2.5 / RD 13 10 XTAL3 P2.3 / A11 9 XTAL4 C8051F930/20-GQ Top View Figure 3.3. LQFP-32 Pinout Diagram (Top View) Rev. 1.4 33 C8051F93x-C8051F92x First character of the trace code identifies the silicon revision Figure 3.4. QFN-32 Package Marking Diagram 34 Rev. 1.4 C8051F93x-C8051F92x First character of the trace code identifies the silicon revision Figure 3.5. QFN-24 Package Marking Diagram Rev. 1.4 35 C8051F93x-C8051F92x First character of the trace code identifies the silicon revision Figure 3.6. LQFP-32 Package Marking Diagram 36 Rev. 1.4 C8051F93x-C8051F92x Figure 3.7. QFN-32 Package Drawing Table 3.2. QFN-32 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A A1 b D D2 e E 0.80 0.00 0.18 0.9 0.02 0.25 5.00 BSC 3.30 0.50 BSC 5.00 BSC 1.00 0.05 0.30 E2 L L1 aaa bbb ddd eee 3.20 0.30 0.00 — — — — 3.30 0.40 — — — — — 3.40 0.50 0.15 0.15 0.10 0.05 0.08 3.20 3.40 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation VHHD except for custom features D2, E2, and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 37 C8051F93x-C8051F92x Figure 3.8. Typical QFN-32 Landing Diagram 38 Rev. 1.4 C8051F93x-C8051F92x Table 3.3. PCB Land Pattern Dimension MIN MAX C1 4.80 4.90 C2 4.80 4.90 E 0.50 BSC X1 0.20 0.30 X2 3.20 3.40 Y1 0.75 0.85 Y2 3.20 3.40 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 1. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 µm minimum, all the way around the pad. Stencil Design 1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 2. The stencil thickness should be 0.125 mm (5 mils). 3. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 4. A 3 x 3 array of 1.0 mm square openings on 1.2 mm pitch should be used for the center ground pad. Card Assembly 1. A No-Clean, Type-3 solder paste is recommended. 2. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 39 C8051F93x-C8051F92x 40 Rev. 1.4 C8051F93x-C8051F92x Figure 3.9. QFN-24 Package Drawing Table 3.4. QFN-24 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A 0.70 0.75 0.80 L 0.30 0.40 0.50 A1 0.00 0.02 0.05 L1 0.00 — 0.15 b 0.18 0.25 0.30 aaa — — 0.15 bbb — — 0.10 ddd — — 0.05 D D2 4.00 BSC 2.55 2.70 2.80 e 0.50 BSC eee — — 0.08 E 4.00 BSC Z — 0.24 — Y — 0.18 — E2 2.55 2.70 2.80 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation WGGD except for custom features D2, E2, Z, Y, and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 40 C8051F93x-C8051F92x Figure 3.10. Typical QFN-24 Landing Diagram 41 Rev. 1.4 C8051F93x-C8051F92x Table 3.5. PCB Land Pattern Dimension MIN MAX C1 3.90 4.00 C2 3.90 4.00 E 0.50 BSC X1 0.20 0.30 X2 2.70 2.80 Y1 0.65 0.75 Y2 2.70 2.80 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 1. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 µm minimum, all the way around the pad. Stencil Design 1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 2. The stencil thickness should be 0.125 mm (5 mils). 3. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 4. A 2 x 2 array of 1.0 x 1.0 mm square openings on 1.30 mm pitch should be used for the center ground pad. Card Assembly 1. A No-Clean, Type-3 solder paste is recommended. 2. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 42 C8051F93x-C8051F92x 43 Rev. 1.4 C8051F93x-C8051F92x Figure 3.11. LQFP-32 Package Diagram Table 3.6. LQFP-32 Package Dimensions Dimension Min Typ Max Dimension Min A — — 1.60 E 9.00 BSC A1 0.05 — 0.15 E1 7.00 BSC A2 1.35 1.40 1.45 L b 0.30 0.37 0.45 aaa 0.20 c 0.09 — 0.20 bbb 0.20 0.45 Typ 0.60 D 9.00 BSC. ccc 0.10 D1 7.00 BSC ddd 0.20 e 0.80 BSC θ 0º 3.5º Max 0.75 7º Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC outline MS-026, variation BBA. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 43 C8051F93x-C8051F92x Figure 3.12. Typical LQFP-32 Landing Diagram Table 3.7. PCB Land Pattern Dimension MIN MAX C1 8.40 8.50 C2 8.40 8.50 E 0.80 BSC X1 0.40 0.50 Y1 1.25 1.35 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 1. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 µm minimum, all the way around the pad. Stencil Design 1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 2. The stencil thickness should be 0.125 mm (5 mils). 3. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. Card Assembly 1. A No-Clean, Type-3 solder paste is recommended. 2. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 44 Rev. 1.4 C8051F93x-C8051F92x 4. Electrical Characteristics Throughout the Electrical Characteristics chapter, “VDD” refers to the VDD/DC+ Supply Voltage. 4.1. Absolute Maximum Specifications Table 4.1. Absolute Maximum Ratings Parameter Conditions Min Typ Max Units Ambient temperature under bias –55 — 125 °C Storage Temperature –65 — 150 °C Voltage on any Port I/O Pin or RST with respect to GND VDD > 2.2 V VDD < 2.2 V –0.3 –0.3 — — 5.8 VDD + 3.6 V Voltage on VBAT with respect to GND One-Cell Mode Two-Cell Mode –0.3 –0.3 — — 2.0 4.0 V Voltage on VDD/DC+ with respect to GND –0.3 — 4.0 V Maximum Total current through VBAT, DCEN, VDD/DC+ or GND — — 500 mA Maximum output current sunk by RST or any Port pin — — 100 mA Maximum total current through all Port pins — — 200 mA DC-DC Converter Output Power — — 110 mW Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Rev. 1.4 45 C8051F93x-C8051F92x 4.2. Electrical Characteristics Table 4.2. Global Electrical Characteristics –40 to +85 °C, 25 MHz system clock unless otherwise specified. See "AN358: Optimizing Low Power Operation of the ‘F9xx" for details on how to achieve the supply current specifications listed in this table. Parameter Conditions Min Typ Max Units Battery Supply Voltage (VBAT) One-Cell Mode Two-Cell Mode 0.9 1.8 1.2 2.4 1.8 3.6 V Supply Voltage (VDD/DC+) One-Cell Mode Two-Cell Mode 1.8 1.8 1.9 2.4 3.6 3.6 V Minimum RAM Data Retention Voltage1 VDD (not in Sleep Mode) VBAT (in Sleep Mode) — — 1.4 0.3 — 0.5 V SYSCLK (System Clock)2 0 — 25 MHz TSYSH (SYSCLK High Time) 18 — — ns TSYSL (SYSCLK Low Time) 18 — — ns Specified Operating Temperature Range –40 — +85 °C Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash) VDD = 1.8–3.6 V, F = 24.5 MHz (includes precision oscillator current) — 4.1 5.0 mA VDD = 1.8–3.6 V, F = 20 MHz (includes low power oscillator current) — 3.5 — mA VDD = 1.8 V, F = 1 MHz VDD = 3.6 V, F = 1 MHz (includes external oscillator/GPIO current) — — 295 365 — — µA µA VDD = 1.8–3.6 V, F = 32.768 kHz (includes SmaRTClock oscillator current) — 90 — µA IDD Frequency Sensitivity3, 5, 6 VDD = 1.8–3.6 V, T = 25 °C, F < 10 MHz (Flash oneshot active, see Section 13.6) — 226 — µA/MHz — 120 — µA/MHz IDD 3, 4, 5, 6 VDD = 1.8–3.6 V, T = 25 °C, F > 10 MHz (Flash oneshot bypassed, see Section 13.6) Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash) IDD4, 6, 7 IDD Frequency Sensitivity1,6,7 46 VDD = 1.8–3.6 V, F = 24.5 MHz (includes precision oscillator current) — 2.5 3.0 mA VDD = 1.8–3.6 V, F = 20 MHz (includes low power oscillator current) — 1.8 — mA VDD = 1.8 V, F = 1 MHz VDD = 3.6 V, F = 1 MHz (includes external oscillator/GPIO current) — — 165 235 — — µA µA VDD = 1.8–3.6 V, F = 32.768 kHz (includes SmaRTClock oscillator current) — 84 — µA VDD = 1.8–3.6 V, T = 25 °C — 95 — µA/MHz Rev. 1.4 C8051F93x-C8051F92x Table 4.2. Global Electrical Characteristics (Continued) –40 to +85 °C, 25 MHz system clock unless otherwise specified. See "AN358: Optimizing Low Power Operation of the ‘F9xx" for details on how to achieve the supply current specifications listed in this table. Parameter Conditions Min Typ Max Units Digital Supply Current—Suspend and Sleep Mode Digital Supply Current6 (Suspend Mode) VDD = 1.8–3.6 V, two-cell mode — 77 — µA Digital Supply Current (Sleep Mode, SmaRTClock running) 1.8 V, T = 25 °C 3.0 V, T = 25 °C 3.6 V, T = 25 °C 1.8 V, T = 85 °C 3.0 V, T = 85 °C 3.6 V, T = 85 °C (includes SmaRTClock oscillator and VBAT Supply Monitor) — — — — — — 0.60 0.75 0.85 1.30 1.60 1.90 — — — — — — µA µA µA µA µA µA Digital Supply Current (Sleep Mode) 1.8 V, T = 25 °C 3.0 V, T = 25 °C 3.6 V, T = 25 °C 1.8 V, T = 85 °C 3.0 V, T = 85 °C 3.6 V, T = 85 °C (includes VBAT supply monitor) — — — — — — 0.05 0.08 0.12 0.75 0.90 1.20 — — — — — — µA µA µA µA µA µA Notes: 1. Based on device characterization data; Not production tested. 2. SYSCLK must be at least 32 kHz to enable debugging. 3. Digital Supply Current depends upon the particular code being executed. The values in this table are obtained with the CPU executing an “sjmp $” loop, which is the compiled form of a while(1) loop in C. One iteration requires 3 CPU clock cycles, and the Flash memory is read on each cycle. The supply current will vary slightly based on the physical location of the sjmp instruction and the number of Flash address lines that toggle as a result. In the worst case, current can increase by up to 30% if the sjmp loop straddles a 128-byte Flash address boundary (e.g., 0x007F to 0x0080). Real-world code with larger loops and longer linear sequences will have few transitions across the 128-byte address boundaries. 4. Includes oscillator and regulator supply current. 5. IDD can be estimated for frequencies 10 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example: VDD = 3.0 V; F = 20 MHz, IDD = 4.1 mA – (25 MHz – 20 MHz) x 0.120 mA/MHz = 3.5 mA. 6. The supply current specifications in Table 4.2 are for two cell mode. The VBAT current in one-cell mode can be estimated using the following equation: Supply Voltage × Supply Current (two-cell mode) VBAT Current (one-cell mode) = ----------------------------------------------------------------------------------------------------------------------------------DC-DC Converter Efficiency × VBAT Voltage The VBAT Voltage is the voltage at the VBAT pin, typically 0.9 to 1.8 V. The Supply Current (two-cell mode) is the data sheet specification for supply current. The Supply Voltage is the voltage at the VDD/DC+ pin, typically 1.8 to 3.3 V (default = 1.9 V). The DC-DC Converter Efficiency can be estimated using Figure 4.3–Figure 4.5. 7. Idle IDD can be estimated by taking the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example: VDD = 3.0 V; F = 5 MHz, Idle IDD = 2.5 mA – (25 MHz – 5 MHz) x 0.095 mA/MHz = 0.6 mA. Rev. 1.4 47 C8051F93x-C8051F92x 4200 F < 10 MHz Oneshot Enabled 4100 4000 F > 10 MHz Oneshot Bypassed 3900 3800 3700 3600 3500 3400 < 170 µA/MHz 3300 3200 3100 3000 200 µA/MHz 2900 2800 2700 2600 215 µA/MHz Supply Current (uA) 2500 2400 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 240 µA/MHz 1300 1200 1100 1000 900 250 µA/MHz 800 700 600 500 400 300 300 µA/MHz 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Frequency (MHz) Figure 4.1. Active Mode Current (External CMOS Clock) 48 Rev. 1.4 21 22 23 24 25 C8051F93x-C8051F92x 4200 4100 4000 3900 3800 3700 3600 3500 3400 3300 3200 3100 3000 2900 2800 2700 2600 Supply Current (uA) 2500 2400 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Frequency (MHz) Figure 4.2. Idle Mode Current (External CMOS Clock) Rev. 1.4 49 C8051F93x-C8051F92x 6:6(/  6:6(/               Efficiency (%)   9%$7 9  9%$7 9  9%$7 9  9%$7 9  9%$7 9  9%$7 9 9%$7 9   X+,QGXFWRUSDFNDJH(65 2KPV 9'''& 90LQLPXP3XOVH:LGWK QV3XOVH6NLSSLQJ'LVDEOHG   1RWH(IILFLHQF\DWKLJKFXUUHQWVPD\EHLPSURYHGE\FKRRVLQJDQ LQGXFWRUZLWKDORZHU(65                                 Load Current (mA) Figure 4.3. Typical DC-DC Converter Efficiency (High Current, VDD/DC+ = 2 V) 50 Rev. 1.4  C8051F93x-C8051F92x 6:6(/  6:6(/              9%$7 9 Efficiency (%)  9%$7 9 9%$7 9  9%$7 9  9%$7 9  9%$7 9 9%$7 9    X+,QGXFWRUSDFNDJH(65 2KPV 9'''& 90LQLPXP3XOVH:LGWK QV 3XOVH6NLSSLQJ'LVDEOHG 1RWH(IILFLHQF\DWKLJKFXUUHQWVPD\EHLPSURYHGE\ FKRRVLQJDQLQGXFWRUZLWKDORZHU(65                                 Load current (mA) Figure 4.4. Typical DC-DC Converter Efficiency (High Current, VDD/DC+ = 3 V) Rev. 1.4 51 C8051F93x-C8051F92x     9%$7 9 9%$7 9 Efficiency (%)  9%$7 9 9%$7 9 9%$7 9  9%$7 9 9%$7 9   X+,QGXFWRUSDFNDJH(65 2KPV 6:6(/ 9'''& 90LQLPXP3XOVH:LGWK QV                 Load current (mA) Figure 4.5. Typical DC-DC Converter Efficiency (Low Current, VDD/DC+ = 2 V) 52 Rev. 1.4 C8051F93x-C8051F92x  X+,QGXFWRUSDFNDJH(65 2KPV 6:6(/ 9'''& 9/RDG&XUUHQW X$    0LQ3XOVH:LGWKQV  0LQ3XOVH:LGWKQV  0LQ3XOVH:LGWKQV 0LQ3XOVH:LGWKQV  9%$7&XUUHQWX$                      9%$79 Figure 4.6. Typical One-Cell Suspend Mode Current Rev. 1.4 53 C8051F93x-C8051F92x Table 4.3. Port I/O DC Electrical Characteristics VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified. Parameters Conditions Min Typ Max IOH = –3 mA, Port I/O push-pull VDD – 0.7 — — IOH = –10 µA, Port I/O push-pull VDD – 0.1 — — Units Output High Voltage High Drive Strength, PnDRV.n = 1 IOH = –10 mA, Port I/O push-pull See Chart V Low Drive Strength, PnDRV.n = 0 IOH = –1 mA, Port I/O push-pull VDD – 0.7 — — IOH = –10 µA, Port I/O push-pull VDD – 0.1 — — — See Chart — IOL = 8.5 mA — — 0.6 IOL = 10 µA — — 0.1 IOL = 25 mA — See Chart — IOH = –3 mA, Port I/O push-pull Output Low Voltage High Drive Strength, PnDRV.n = 1 V Low Drive Strength, PnDRV.n = 0 Input High Voltage Input Low Voltage Input Leakage Current 54 IOL = 1.4 mA — — 0.6 IOL = 10 µA — — 0.1 IOL = 4 mA — See Chart — VDD = 2.0 to 3.6 V VDD – 0.6 — — V VDD = 0.9 to 2.0 V 0.7 x VDD — — V VDD = 2.0 to 3.6 V — — 0.6 V VDD = 0.9 to 2.0 V — — 0.3 x VDD V Weak Pullup Off — — ±1 Weak Pullup On, VIN = 0 V, VDD = 1.8 V — 4 — Weak Pullup On, Vin = 0 V, VDD = 3.6 V — 20 30 Rev. 1.4 µA C8051F93x-C8051F92x Typical VOH (High Drive Mode) 3.6 VDD = 3.6V Voltage 3.3 3 VDD = 3.0V 2.7 VDD = 2.4V 2.4 VDD = 1.8V 2.1 1.8 1.5 1.2 0.9 0 5 10 15 20 25 30 35 40 45 50 Load Current (mA) Typical VOH (Low Drive Mode) Voltage 3.6 3.3 VDD = 3.6V 3 VDD = 3.0V 2.7 VDD = 2.4V 2.4 VDD = 1.8V 2.1 1.8 1.5 1.2 0.9 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Load Current (mA) Figure 4.7. Typical VOH Curves, 1.8–3.6 V Rev. 1.4 55 C8051F93x-C8051F92x Typical VOH (High Drive Mode) 1.8 1.7 VDD = 1.8V 1.6 VDD = 1.5V 1.5 1.4 VDD = 1.2V Voltage 1.3 VDD = 0.9V 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0 1 2 3 4 5 6 7 8 9 10 11 12 Load Current (mA) Typical VOH (Low Drive Mode) 1.8 1.7 VDD = 1.8V 1.6 VDD = 1.5V 1.5 1.4 VDD = 1.2V Voltage 1.3 1.2 VDD = 0.9V 1.1 1 0.9 0.8 0.7 0.6 0.5 0 1 2 3 Load Current (mA) Figure 4.8. Typical VOH Curves, 0.9–1.8 V 56 Rev. 1.4 C8051F93x-C8051F92x Typical VOL (High Drive Mode) 1.8 VDD = 3.6V 1.5 VDD = 3.0V Voltage 1.2 VDD = 2.4V VDD = 1.8V 0.9 0.6 0.3 0 -80 -70 -60 -50 -40 -30 -20 -10 0 Load Current (mA) Typical VOL (Low Drive Mode) 1.8 VDD = 3.6V 1.5 VDD = 3.0V Voltage 1.2 VDD = 2.4V VDD = 1.8V 0.9 0.6 0.3 0 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 Load Current (mA) Figure 4.9. Typical VOL Curves, 1.8–3.6 V Rev. 1.4 57 C8051F93x-C8051F92x Typical VOL (High Drive Mode) 0.5 VDD = 1.8V Voltage 0.4 VDD = 1.5V VDD = 1.2V 0.3 VDD = 0.9V 0.2 0.1 0 -5 -4 -3 -2 -1 0 Load Current (mA) Typical VOL (Low Drive Mode) 0.5 Voltage 0.4 0.3 VDD = 1.8V 0.2 VDD = 1.5V VDD = 1.2V 0.1 VDD = 0.9V 0 -3 -2 -1 0 Load Current (mA) Figure 4.10. Typical VOL Curves, 0.9–1.8 V 58 Rev. 1.4 C8051F93x-C8051F92x Table 4.4. Reset Electrical Characteristics VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units — — 0.6 V RST Output Low Voltage IOL = 1.4 mA, RST Input High Voltage VDD = 2.0 to 3.6 V VDD – 0.6 — — V VDD = 0.9 to 2.0 V 0.7 x VDD — — V VDD = 2.0 to 3.6 V — — 0.6 V VDD = 0.9 to 2.0 V — — 0.3 x VDD V RST Input Pullup Current RST = 0.0 V, VDD = 1.8 V RST = 0.0 V, VDD = 3.6 V — 4 — — 20 30 VDD/DC+ Monitor Threshold (VRST) Early Warning Reset Trigger (all power modes except Sleep) 1.8 1.85 1.9 1.7 1.75 1.8 VBAT Ramp Time for Power On One-cell Mode: VBAT Ramp 0–0.9 V Two-cell Mode: VBAT Ramp 0–1.8 V — — 3 VBAT Monitor Threshold (VPOR) Initial Power-On (VBAT Rising) Brownout Condition (VBAT Falling) Recovery from Brownout (VBAT Rising) — 0.75 — 0.7 0.8 0.9 — 0.95 — Missing Clock Detector Timeout Time from last system clock rising edge to reset initiation 100 650 1000 µs Minimum System Clock w/ Missing Clock Detector Enabled System clock frequency which triggers a missing clock detector timeout — 7 10 kHz Reset Time Delay Delay between release of any reset source and code execution at location 0x0000 — 10 — µs Minimum RST Low Time to Generate a System Reset 15 — — µs VDD Monitor Turn-on Time — 300 — ns VDD Monitor Supply Current — 7 — µA RST Input Low Voltage Rev. 1.4 µA V ms V 59 C8051F93x-C8051F92x Table 4.5. Power Management Electrical Specifications VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified. Parameter Conditions Min Typ Max Units Idle Mode Wake-up Time 2 — 3 SYSCLKs Suspend Mode Wake-up Time Low power oscillator — 400 — ns Precision oscillator — 1.3 — µs Two-cell mode — 2 — µs One-cell mode — 10 — µs Sleep Mode Wake-up Time Table 4.6. Flash Electrical Characteristics VDD = 1.8 to 3.6 V, –40 to +85 °C unless otherwise specified. Parameter Flash Size Conditions C8051F930/1 C8051F920/1 Min 65536* 32768 1024 Typ — — — Max — — 1024 Endurance 1k 30k — Erase Cycle Time Write Cycle Time 28 57 32 64 36 71 Scratchpad Size Units bytes bytes bytes Erase/Write Cycles ms µs *Note: 1024 bytes at addresses 0xFC00 to 0xFFFF are reserved. Table 4.7. Internal Precision Oscillator Electrical Characteristics VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified; Using factory-calibrated settings. Parameter Conditions Min Typ Max Units Oscillator Frequency –40 to +85 °C, VDD = 1.8–3.6 V 24 24.5 25 MHz Oscillator Supply Current (from VDD) 25 °C; includes bias current of 90–100 µA — 300* — µA *Note: Does not include clock divider or clock tree supply current. Table 4.8. Internal Low-Power Oscillator Electrical Characteristics VDD = 1.8 to 3.6 V; TA = –40 to +85 °C unless otherwise specified; Using factory-calibrated settings. Parameter Oscillator Frequency Oscillator Supply Current (from VDD) Conditions –40 to +85 °C, VDD = 1.8–3.6 V 25 °C No separate bias current required. *Note: Does not include clock divider or clock tree supply current. 60 Rev. 1.4 Min Typ Max Units 18 20 22 MHz — 100* — µA C8051F93x-C8051F92x Table 4.9. ADC0 Electrical Characteristics VDD = 1.8 to 3.6V V, VREF = 1.65 V (REFSL[1:0] = 11), –40 to +85 °C unless otherwise specified. Parameter Conditions DC Accuracy Min Resolution Typ Max 10 Integral Nonlinearity Units bits — ±0.5 ±1 LSB — ±0.5 ±1 LSB Offset Error — ±> 1; CRC_acc ^= POLY; } else { // if not, just shift the CRC value CRC_acc = CRC_acc >> 1; } } // Return the final remainder (CRC value) return CRC_acc; } The following table lists several input values and the associated outputs using the 32-bit 'F93x/92x CRC algorithm (an initial value of 0xFFFFFFFF is used): Rev. 1.4 169 C8051F93x-C8051F92x Table 15.2. Example 32-bit CRC Outputs Input Output 0x63 0xF9462090 0xAA, 0xBB, 0xCC 0x41B207B3 0x00, 0x00, 0xAA, 0xBB, 0xCC 0x78D129BC 15.3. Preparing for a CRC Calculation To prepare CRC0 for a CRC calculation, software should select the desired polynomial and set the initial value of the result. Two polynomials are available: 0x1021 (16-bit) and 0x04C11DB7 (32-bit). The CRC0 result may be initialized to one of two values: 0x00000000 or 0xFFFFFFFF. The following steps can be used to initialize CRC0. 1. Select a polynomial (Set CRC0SEL to 0 for 32-bit or 1 for 16-bit). 2. Select the initial result value (Set CRC0VAL to 0 for 0x00000000 or 1 for 0xFFFFFFFF). 3. Set the result to its initial value (Write 1 to CRC0INIT). 15.4. Performing a CRC Calculation Once CRC0 is initialized, the input data stream is sequentially written to CRC0IN, one byte at a time. The CRC0 result is automatically updated after each byte is written. The CRC engine may also be configured to automatically perform a CRC on one or more Flash sectors. The following steps can be used to automatically perform a CRC on Flash memory. 1. 2. 3. 4. Prepare CRC0 for a CRC calculation as shown above. Write the index of the starting page to CRC0AUTO. Set the AUTOEN bit in CRC0AUTO. Write the number of Flash sectors to perform in the CRC calculation to CRC0CNT. Note: Each Flash sector is 1024 bytes. 5. Write any value to CRC0CN (or OR its contents with 0x00) to initiate the CRC calculation. The CPU will not execute code any additional code until the CRC operation completes. See the note in SFR Definition 15.1. CRC0CN: CRC0 Control for more information on how to properly initiate a CRC calculation. 6. Clear the AUTOEN bit in CRC0AUTO. 7. Read the CRC result using the procedure below. 15.5. Accessing the CRC0 Result The internal CRC0 result is 32-bits (CRC0SEL = 0b) or 16-bits (CRC0SEL = 1b). The CRC0PNT bits select the byte that is targeted by read and write operations on CRC0DAT and increment after each read or write. The calculation result will remain in the internal CR0 result register until it is set, overwritten, or additional data is written to CRC0IN. 170 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 15.1. CRC0CN: CRC0 Control Bit 7 6 5 4 3 2 CRC0SEL CRC0INIT CRC0VAL Name Type R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 SFR Page = 0xF; SFR Address = 0x92 Bit Name 7:5 Unused 1 0 CRC0PNT[1:0] R/W 0 0 Function Unused. Read = 000b; Write = Don’t Care. 4 CRC0SEL CRC0 Polynomial Select Bit. This bit selects the CRC0 polynomial and result length (32-bit or 16-bit). 0: CRC0 uses the 32-bit polynomial 0x04C11DB7 for calculating the CRC result. 1: CRC0 uses the 16-bit polynomial 0x1021 for calculating the CRC result. 3 CRC0INIT CRC0 Result Initialization Bit. Writing a 1 to this bit initializes the entire CRC result based on CRC0VAL. 2 CRC0VAL CRC0 Set Value Initialization Bit. This bit selects the set value of the CRC result. 0: CRC result is set to 0x00000000 on write of 1 to CRC0INIT. 1: CRC result is set to 0xFFFFFFFF on write of 1 to CRC0INIT. 1:0 CRC0PNT[1:0] CRC0 Result Pointer. Specifies the byte of the CRC result to be read/written on the next access to CRC0DAT. The value of these bits will auto-increment upon each read or write. For CRC0SEL = 0: 00: CRC0DAT accesses bits 7–0 of the 32-bit CRC result. 01: CRC0DAT accesses bits 15–8 of the 32-bit CRC result. 10: CRC0DAT accesses bits 23–16 of the 32-bit CRC result. 11: CRC0DAT accesses bits 31–24 of the 32-bit CRC result. For CRC0SEL = 1: 00: CRC0DAT accesses bits 7–0 of the 16-bit CRC result. 01: CRC0DAT accesses bits 15–8 of the 16-bit CRC result. 10: CRC0DAT accesses bits 7–0 of the 16-bit CRC result. 11: CRC0DAT accesses bits 15–8 of the 16-bit CRC result. Note: Upon initiation of an automatic CRC calculation, the third opcode byte fetched from program memory is indeterminate. Therefore, writes to CRC0CN that initiate a CRC operation must be immediately followed by a benign 3-byte instruction whose third byte is a don’t care. An example of such an instruction is a 3-byte MOV that targets the CRC0FLIP register. When programming in ‘C’, the dummy value written to CRC0FLIP should be a non-zero value to prevent the compiler from generating a 2-byte MOV instruction. Rev. 1.4 171 C8051F93x-C8051F92x SFR Definition 15.2. CRC0IN: CRC0 Data Input Bit 7 6 5 4 3 Name CRC0IN[7:0] Type R/W Reset 0 0 0 0 0 SFR Page = 0xF; SFR Address = 0x93 Bit Name 7:0 CRC0IN[7:0] 2 1 0 0 0 0 Function CRC0 Data Input. Each write to CRC0IN results in the written data being computed into the existing CRC result according to the CRC algorithm described in Section 15.1 SFR Definition 15.3. CRC0DAT: CRC0 Data Output Bit 7 6 5 4 3 Name CRC0DAT[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0xF; SFR Address = 0x91 Bit Name 0 2 1 0 0 0 0 Function 7:0 CRC0DAT[7:0] CRC0 Data Output. Each read or write performed on CRC0DAT targets the CRC result bits pointed to by the CRC0 Result Pointer (CRC0PNT bits in CRC0CN). 172 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 15.4. CRC0AUTO: CRC0 Automatic Control Bit 7 6 Name AUTOEN CRCDONE 5 4 3 2 1 CRC0ST[5:0] R/W Type Reset 0 1 0 AUTOEN R/W 0 0 SFR Page = 0xF; SFR Address = 0x96 Bit Name 7 0 0 0 0 Function Automatic CRC Calculation Enable. When AUTOEN is set to 1, any write to CRC0CN will initiate an automatic CRC starting at Flash sector CRC0ST and continuing for CRC0CNT sectors. 6 CRCDONE CRCDONE Automatic CRC Calculation Complete. Set to 0 when a CRC calculation is in progress. Note that code execution is stopped during a CRC calculation, therefore reads from firmware will always return 1. 5:0 CRC0ST[5:0] Automatic CRC Calculation Starting Flash Sector. These bits specify the Flash sector to start the automatic CRC calculation. The starting address of the first Flash sector included in the automatic CRC calculation is CRC0ST x 1024. SFR Definition 15.5. CRC0CNT: CRC0 Automatic Flash Sector Count Bit 7 6 5 4 3 1 R/W Type Reset 0 CRC0CNT[5:0] Name 0 0 0 R/W 0 0 SFR Page = 0xF; SFR Address = 0x97 Bit Name 7:6 2 Unused 0 0 0 Function Unused. Read = 00b; Write = Don’t Care. 5:0 CRC0CNT[5:0] Automatic CRC Calculation Flash Sector Count. These bits specify the number of Flash sectors to include in an automatic CRC calculation. The starting address of the last Flash sector included in the automatic CRC calculation is (CRC0ST+CRC0CNT) x 1024. Rev. 1.4 173 C8051F93x-C8051F92x 15.6. CRC0 Bit Reverse Feature CRC0 includes hardware to reverse the bit order of each bit in a byte as shown in Figure 15.2. Each byte of data written to CRC0FLIP is read back bit reversed. For example, if 0xC0 is written to CRC0FLIP, the data read back is 0x03. Bit reversal is a useful mathematical function used in algorithms such as the FFT. CRC0FLIP Write CRC0FLIP Read Figure 15.2. Bit Reverse Register SFR Definition 15.6. CRC0FLIP: CRC0 Bit Flip Bit 7 6 5 4 3 Name CRC0FLIP[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0xF; SFR Address = 0x95 Bit Name 7:0 CRC0FLIP[7:0] 0 2 1 0 0 0 0 Function CRC0 Bit Flip. Any byte written to CRC0FLIP is read back in a bit-reversed order, i.e. the written LSB becomes the MSB. For example: If 0xC0 is written to CRC0FLIP, the data read back will be 0x03. If 0x05 is written to CRC0FLIP, the data read back will be 0xA0. 174 Rev. 1.4 C8051F93x-C8051F92x 16. On-Chip DC-DC Converter (DC0) C8051F93x-C8051F92x devices include an on-chip dc-dc converter to allow operation from a single cell battery with a supply voltage as low as 0.9 V. The dc-dc converter is a switching boost converter with an input voltage range of 0.9 to 1.8 V and a programmable output voltage range of 1.8 to 3.3 V. The default output voltage is 1.9 V. The dc-dc converter can supply the system with up to 65 mW of regulated power (or up to 100 mW in some applications) and can be used for powering other devices in the system. This allows the most flexibility when interfacing to sensors and other analog signals which typically require a higher supply voltage than a single-cell battery can provide. Figure 16.1 shows a block diagram of the dc-dc converter. During normal operation in the first half of the switching cycle, the Duty Cycle Control switch is closed and the Diode Bypass switch is open. Since the output voltage is higher than the voltage at the DCEN pin, no current flows through the diode and the load is powered from the output capacitor. During this stage, the DCEN pin is connected to ground through the Duty Cycle Control switch, generating a positive voltage across the inductor and forcing its current to ramp up. In the second half of the switching cycle, the Duty Cycle control switch is opened and the Diode Bypass switch is closed. This connects DCEN directly to VDD/DC+ and forces the inductor current to charge the output capacitor. Once the inductor transfers its stored energy to the output capacitor, the Duty Cycle Control switch is closed, the Diode Bypass switch is opened, and the cycle repeats. The dc-dc converter has a built in voltage reference and oscillator, and will automatically limit or turn off the switching activity in case the peak inductor current rises beyond a safe limit or the output voltage rises above the programmed target value. This allows the dc-dc converter output to be safely overdriven by a secondary power source (when available) in order to preserve battery life. The dc-dc converter’s settings can be modified using SFR registers which provide the ability to change the target output voltage, oscillator frequency or source, Diode Bypass switch resistance, peak inductor current, and minimum duty cycle. DC/DC Converter VBAT VDD/DC+ 0.68 uH DCEN Diode Bypass 4.7 uF Duty Cycle Control GND Control Logic DC0CN Voltage Reference DC0CF DC/DC Oscillator Lparasitic Lparasitic 1uF Iload Cload GND/DC- Figure 16.1. DC-DC Converter Block Diagram Rev. 1.4 175 C8051F93x-C8051F92x 16.1. Startup Behavior On initial power-on, the dc-dc converter outputs a constant 50% duty cycle until there is sufficient voltage on the output capacitor to maintain regulation. The size of the output capacitor and the amount of load current present during startup will determine the length of time it takes to charge the output capacitor. During initial power-on reset, the maximum peak inductor current threshold, which triggers the overcurrent protection circuit, is set to approximately 125 mA. This generates a “soft-start” to limit the output voltage slew rate and prevent excessive in-rush current at the output capacitor. In order to ensure reliable startup of the dc-dc converter, the following restrictions have been imposed: • The maximum dc load current allowed during startup is given in Table 4.14 on page 66. If the dc-dc converter is powering external sensors or devices through the VDD/DC+ pin or through GPIO pins, then the current supplied to these sensors or devices is counted towards this limit. The in-rush current into capacitors does not count towards this limit. • The maximum total output capacitance is given in Table 4.14 on page 66. This value includes the required 1 µF ceramic output capacitor and any additional capacitance connected to the VDD/DC+ pin. Once initial power-on is complete, the peak inductor current limit can be increased by software as shown in Table 16.1. Limiting the peak inductor current can allow the device to start up near the battery’s end of life. . Table 16.1. IPeak Inductor Current Limit Settings SWSEL ILIMIT Peak Current (mA) 1 0 100 0 0 125 1 1 250 0 1 500 The peak inductor current is dependent on several factors including the dc load current and can be estimated using following equation: 2 I LOAD ( VDD/DC+ – VBAT ) I PK = --------------------------------------------------------------------------------------------------efficiency × inductance × frequency efficiency = 0.80 inductance = 0.68 µH frequency = 2.4 MHz 176 Rev. 1.4 C8051F93x-C8051F92x 16.2. High Power Applications The dc-dc converter is designed to provide the system with 65 mW of output power, however, it can safely provide up to 100 mW of output power without any risk of damage to the device. For high power applications, the system should be carefully designed to prevent unwanted VBAT and VDD/DC+ Supply Monitor resets, which are more likely to occur when the dc-dc converter output power exceeds 65mW. In addition, output power above 65 mW causes the dc-dc converter to have relaxed output regulation, high output ripple and more analog noise. At high output power, an inductor with low DC resistance should be chosen in order to minimize power loss and maximize efficiency. The combination of high output power and low input voltage will result in very high peak and average inductor currents. If the power supply has a high internal resistance, the transient voltage on the VBAT terminal could drop below 0.9 V and trigger a VBAT Supply Monitor Reset, even if the open-circuit voltage is well above the 0.9 V threshold. While this problem is most often associated with operation from very small batteries or batteries that are near the end of their useful life, it can also occur when using bench power supplies that have a slow transient response; the supply’s display may indicate a voltage above 0.9 V, but the minimum voltage on the VBAT pin may be lower. A similar problem can occur at the output of the dc-dc converter: using the default low current limit setting (125 mA) can trigger VDD Supply Monitor resets if there is a high transient load current, particularly if the programmed output voltage is at or near 1.8 V. 16.3. Pulse Skipping Mode The dc-dc converter allows the user to set the minimum pulse width such that if the duty cycle needs to decrease below a certain width in order to maintain regulation, an entire "clock pulse" will be skipped. Pulse skipping can provide substantial power savings, particularly at low values of load current. The converter will continue to maintain a minimum output voltage at its programmed value when pulse skipping is employed, though the output voltage ripple can be higher. Another consideration is that the dc-dc will operate with pulse-frequency modulation rather than pulse-width modulation, which makes the switching frequency spectrum less predictable; this could be an issue if the dc-dc converter is used to power a radio. Figure 4.5 and Figure 4.6 on page 52 and 53 show the effect of pulse skipping on power consumption. Rev. 1.4 177 C8051F93x-C8051F92x 16.4. Enabling the DC-DC Converter On power-on reset, the state of the DCEN pin is sampled to determine if the device will power up in onecell or two-cell mode. In two-cell mode, the dc-dc converter always remains disabled. In one-cell mode, the dc-dc converter remains disabled in Sleep Mode, and enabled in all other power modes. See Section “14. Power Management” on page 159 for complete details on available power modes. The dc-dc converter is enabled (one-cell mode) in hardware by placing a 0.68 µH inductor between DCEN and VBAT. The dc-dc converter is disabled (two-cell mode) by shorting DCEN directly to GND. The DCEN pin should never be left floating. Note that the device can only switch between one-cell and two-cell mode during a power-on reset. See Section “18. Reset Sources” on page 184 for more information regarding reset behavior. Figure 16.2 shows the two dc-dc converter configuration options. 0.68 uH DC-DC Converter Enabled 0.9 to 1.8 V Supply Voltage 1 uF 4.7 uF VBAT GND DCEN VDD/DC+ GND/DC- VBAT GND DCEN VDD/DC+ GND/DC- (one-cell mode) DC-DC Converter Disabled 1.8 to 3.6 V Supply Voltage (two-cell mode) Figure 16.2. DC-DC Converter Configuration Options When the dc-dc converter “Enabled” configuration (one-cell mode) is chosen, the following guidelines apply: • • • • • 178 In most cases, the GND/DC– pin should not be externally connected to GND. The 0.68 µH inductor should be placed as close as possible to the DCEN pin for maximum efficiency. The 4.7 µF capacitor should be placed as close as possible to the inductor. The current loop including GND, the 4.7 µF capacitor, the 0.68 µH inductor and the DCEN pin should be made as short as possible. The PCB traces connecting VDD/DC+ to the output capacitor and the output capacitor to GND/DC– should be as short and as thick as possible in order to minimize parasitic inductance. Rev. 1.4 C8051F93x-C8051F92x 16.5. Minimizing Power Supply Noise To minimize noise on the power supply lines, the GND and GND/DC- pins should be kept separate, as shown in Figure 16.2; one or the other should be connected to the pc board ground plane. For applications in which the dc-dc converter is used only to power internal circuits, the GND pin is normally connected to the board ground. The large decoupling capacitors in the input and output circuits ensure that each supply is relatively quiet with respect to its own ground. However, connecting a circuit element "diagonally" (e.g. connecting an external chip between VDD/DC+ and GND, or between VBAT and GND/DC-) can result in high supply noise across that circuit element. For applications in which the dc-dc converter is used to power external analog circuitry, it is recommended to connect the GND/DC– pin to the board ground and connect the battery’s negative terminal to the GND pin only, which is not connected to board ground. To accommodate situations in which ADC0 is sampling a signal that is referenced to one of the external grounds, we recommend using the Analog Ground Reference (P0.1/AGND) option described in Section 5.12. This option prevents any voltage differences between the internal chip ground and the external grounds from modulating the ADC input signal. If this option is enabled, the P0.1 pin should be tied to the ground reference of the external analog input signal. When using the ADC with the dc-dc converter, we also recommend enabling the SYNC bit in the DC0CN register to minimize interference. These general guidelines provide the best performance in most applications, though some situations may benefit from experimentation to eliminate any residual noise issues. Examples might include tying the grounds together, using additional low-inductance decoupling caps in parallel with the recommended ones, investigating the effects of different dc-dc converter settings, etc. 16.6. Selecting the Optimum Switch Size The dc-dc converter has two built-in switches (the diode bypass switch and duty cycle control switch). To maximize efficiency, one of two switch sizes may be selected. The large switches are ideal for carrying high currents and the small switches are ideal for low current applications. The ideal switchover point to switch from the small switches to the large switches varies with the programmed output voltage. At an output voltage of 2 V, the ideal switchover point is at approximately 4 mA total output current. At an output voltage of 3 V, the ideal switchover point is at approximately 8 mA total output current. 16.7. DC-DC Converter Clocking Options The dc-dc converter may be clocked from its internal oscillator, or from any system clock source, selectable by the CLKSEL bit (DC0CF.0). The dc-dc converter internal oscillator frequency is approximately 2.4 MHz. For a more accurate clock source, the system clock, or a divided version of the system clock may be used as the dc-dc clock source. The dc-dc converter has a built in clock divider (configured using DC0CF[6:5]) which allows any system clock frequency over 1.6 MHz to generate a valid clock in the range of 1.6 to 3.2 MHz. When the precision internal oscillator is selected as the system clock source, the OSCICL register may be used to fine tune the oscillator frequency and the dc-dc converter clock. The oscillator frequency should only be decreased since it is factory calibrated at its maximum frequency. The minimum frequency which can be reached by the oscillator after taking into account process variations is approximately 16 MHz. The system clock routed to the dc-dc converter clock divider also may be inverted by setting the CLKINV bit (DC0CF.3) to logic 1. These options can be used to minimize interference in noise sensitive applications. Rev. 1.4 179 C8051F93x-C8051F92x 16.8. DC-DC Converter Behavior in Sleep Mode When the C8051F93x-C8051F92x devices are placed in Sleep mode, the dc-dc converter is disabled, and the VDD/DC+ output is internally connected to VBAT by default. This behavior ensures that the GPIO pins are powered from a low-impedance source during sleep mode. If the GPIO pins are not used as inputs or outputs during sleep mode, then the VDD/DC+ output can be made to float during Sleep mode by setting the VDDSLP bit in the DC0CF register to 1. Setting this bit can provide power savings in two ways. First, if the sleep interval is relatively short and the VDD/DC+ load current (include leakage currents) is negligible, then the capacitor on VDD/DC+ will maintain the output voltage near the programmed value, which means that the VDD/DC+ capacitor will not need to be recharged upon every wake up event. The second power advantage is that internal or external lowpower circuits that require more than 1.8 V can continue to function during Sleep mode without operating the dc-dc converter, powered by the energy stored in the 1 µF output decoupling capacitor. For example, the C8051F93x-C8051F92x comparators require about 0.4 µA when operating in their lowest power mode. If the dc-dc converter output were increased to 3.3 V just before putting the device into Sleep mode, then the comparator could be powered for more than 3 seconds before the output voltage dropped to 1.8 V. In this example, the overall energy consumption would be much lower than if the dc-dc converter were kept running to power the comparator. If the load current on VDD/DC+ is high enough to discharge the VDD/DC+ capacitance to a voltage lower than VBAT during the sleep interval, an internal diode will prevent VDD/DC+ from dropping more than a few hundred millivolts below VBAT. There may be some additional leakage current from VBAT to ground when the VDD/DC+ level falls below VBAT, but this leakage current should be small compared to the current from VDD/DC+. The amount of time that it takes for a device configured in one-cell mode to wake up from Sleep mode depends on a number of factors, including the dc-dc converter clock speed, the settings of the SWSEL and ILIMIT bits, the battery internal resistance, the load current, and the difference between the VBAT voltage level and the programmed output voltage. The wake up time can be as short as 2 µs, though it is more commonly in the range of 5 to 10 µs, and it can exceed 50 µs under extreme conditions. See Section “14. Power Management” on page 159 for more information about sleep mode. 180 Rev. 1.4 C8051F93x-C8051F92x 16.9. DC-DC Converter Register Descriptions The SFRs used to configure the dc-dc converter are described in the following register descriptions. The reset values for these registers can be used as-is in most systems; therefore, no software intervention or initialization is required. SFR Definition 16.1. DC0CN: DC-DC Converter Control Bit 7 6 5 4 3 2 1 Name MINPW SWSEL Reserved SYNC VSEL Type R/W R/W R/W R/W R/W 1 0 0 Reset 0 0 SFR Page = 0x0; SFR Address = 0x97 Bit Name 7:6 0 0 0 1 Function MINPW[1:0] DC-DC Converter Minimum Pulse Width. Specifies the minimum pulse width. 00: No minimum duty cycle. 01: Minimum pulse width is 20 ns. 10: Minimum pulse width is 40 ns. 11: Minimum pulse width is 80 ns. 5 SWSEL DC-DC Converter Switch Select. Selects one of two possible converter switch sizes to maximize efficiency. 0: The large switches are selected (best efficiency for high output currents). 1: The small switches are selected (best efficiency for low output currents). 4 Reserved 3 SYNC Reserved. Always Write to 0. ADC0 Synchronization Enable. When synchronization is enabled, the ADC0SC[4:0] bits in the ADC0CF register must be set to 00000b. Behavior as described is valid in REVC and later devices. 0: The ADC is not synchronized to the dc-dc converter. 1: The ADC is synchronized to the dc-dc converter. ADC0 tracking is performed during the longest quiet time of the dc-dc converter switching cycle and ADC0 SAR clock is also synchronized to the dc-dc converter switching cycle. 2:0 VSEL[2:0] DC-DC Converter Output Voltage Select. Specifies the target output voltage. 000: Target output voltage is 1.8 V. 001: Target output voltage is 1.9 V. 010: Target output voltage is 2.0 V. 011: Target output voltage is 2.1 V. 100: Target output voltage is 2.4 V. 101: Target output voltage is 2.7 V. 110: Target output voltage is 3.0 V. 111: Target output voltage is 3.3 V. Rev. 1.4 181 C8051F93x-C8051F92x SFR Definition 16.2. DC0CF: DC-DC Converter Configuration Bit 7 6 Name Reserved Type R R/W Reset 0 0 5 4 3 2 1 0 AD0CKINV CLKINV ILIMIT VDDSLP CLKSEL R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 CLKDIV[1:0] SFR Page = 0x0; SFR Address = 0x96 Bit Name 7 Reserved Reserved. 6:5 4 3 Function Read = 0b; Must write 0b. CLKDIV[1:0] DC-DC Clock Divider. Divides the dc-dc converter clock when the system clock is selected as the clock source for dc-dc converter. These bits are ignored when the dc-dc converter is clocked from its local oscillator. 00: The dc-dc converter clock is system clock divided by 1. 01: The dc-dc converter clock is system clock divided by 2. 10: The dc-dc converter clock is system clock divided by 4. 11: The dc-dc converter clock is system clock divided by 8. AD0CKINV ADC0 Clock Inversion (Clock Invert During Sync). Inverts the ADC0 SAR clock derived from the dc-dc converter clock when the SYNC bit (DC0CN.3) is enabled. This bit is ignored when the SYNC bit is set to zero. 0: ADC0 SAR clock is inverted. 1: ADC0 SAR clock is not inverted. CLKINV DC-DC Converter Clock Invert. Inverts the system clock used as the input to the dc-dc clock divider. 0: The dc-dc converter clock is not inverted. 1: The dc-dc converter clock is inverted. 2 ILIMIT Peak Current Limit Threshold. Sets the threshold for the maximum allowed peak inductor current. See Table 16.1 for peak inductor current levels. 0: Peak inductor current is set at a lower level. 1: Peak inductor current is set at a higher level. 1 0 VDDSLP VDD-DC+ Sleep Mode Connection. CLKSEL Specifies the power source for VDD/DC+ in Sleep Mode when the dc-dc converter is enabled. 0: VDD-DC+ connected to VBAT in Sleep Mode. 1: VDD-DC+ is floating in Sleep Mode. DC-DC Converter Clock Source Select. Specifies the dc-dc converter clock source. 0: The dc-dc converter is clocked from its local oscillator. 1: The dc-dc converter is clocked from the system clock. 16.10. DC-DC Converter Specifications See Table 4.14 on page 66 for a detailed listing of dc-dc converter specifications. 182 Rev. 1.4 C8051F93x-C8051F92x 17. Voltage Regulator (VREG0) C8051F93x-C8051F92x devices include an internal voltage regulator (VREG0) to regulate the internal core supply to 1.8 V from a VDD/DC+ supply of 1.8 to 3.6 V. Electrical characteristics for the on-chip regulator are specified in the Electrical Specifications chapter. The REG0CN register allows the Precision Oscillator Bias to be disabled, reducing supply current in all non-sleep power modes. This bias should only be disabled when the precision oscillator is not being used. The internal regulator (VREG0) is disabled when the device enters sleep mode and remains enabled when the device enters suspend mode. See Section “14. Power Management” on page 159 for complete details about low power modes. SFR Definition 17.1. REG0CN: Voltage Regulator Control Bit 7 Name 6 5 4 3 Reserved Reserved OSCBIAS 2 1 0 Reserved Type R R/W R/W R/W R R R R/W Reset 0 0 0 1 0 0 0 0 SFR Page = 0x0; SFR Address = 0xC9 Bit Name 7 Unused Function Unused. Read = 0b. Write = Don’t care. 6 Reserved Reserved. Read = 0b. Must Write 0b. 5 Reserved Reserved. Read = 0b. Must Write 0b. 4 OSCBIAS Precision Oscillator Bias. When set to 1, the bias used by the precision oscillator is forced on. If the precision oscillator is not being used, this bit may be cleared to 0 to save approximately 80 µA of supply current in all non-Sleep power modes. If disabled then re-enabled, the precision oscillator bias requires 4 µs of settling time. 3:1 Unused Unused. Read = 000b. Write = Don’t care. 0 Reserved Reserved. Read = 0b. Must Write 0b. 17.1. Voltage Regulator Electrical Specifications See Table 4.15 on page 66 for detailed Voltage Regulator Electrical Specifications. Rev. 1.4 183 C8051F93x-C8051F92x 18. 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 descriptions. The contents of RAM are unaffected during a reset; any previously stored data is preserved as long as power is not lost. Since the stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered. The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled during and after the reset. For power-on resets, the RST pin is high-impedance with the weak pull-up either on or off until the device exits the reset state. For VDD Monitor resets, the RST pin is driven low until the device exits the reset state. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to an internal oscillator. Refer to Section “19. Clocking Sources” on page 191 for information on selecting and configuring the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock source (Section “26.4. Watchdog Timer Mode” on page 316 details the use of the Watchdog Timer). Program execution begins at location 0x0000. VDD/DC+ + - Px.x Power On Reset Supply Monitor Comparator 0 Px.x VBAT + - Enable C0RSEF RST '0' RTC0RE Missing Clock Detector (oneshot) EN Reset Funnel PCA WDT (Software Reset) SWRSF EN System Clock Illegal Flash Operation WDT Enable MCD Enable SmaRTClock CIP-51 Microcontroller Core System Reset System Reset Power Management Block (PMU0) Power-On Reset Reset Extended Interrupt Handler Figure 18.1. Reset Sources Rev. 1.4 184 C8051F93x-C8051F92x 18.1. Power-On (VBAT Supply Monitor) Reset During power-up, the device is held in a reset state and the RST pin is high-impedance with the weak pullup either on or off until VBAT settles above VPOR. An additional delay occurs before the device is released from reset; the delay decreases as the VBAT ramp time increases (VBAT ramp time is defined as how fast VBAT ramps from 0 V to VPOR). Figure 18.3 plots the power-on and VDD monitor reset timing. For valid ramp times (less than 3 ms), the power-on reset delay (TPORDelay) is typically 3 ms (VBAT = 0.9 V), 7 ms (VBAT = 1.8 V), or 15 ms (VBAT = 3.6 V). Note: The maximum VDD ramp time is 3 ms; slower ramp times may cause the device to be released from reset before VBAT reaches the VPOR level. volts On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is set, all of the other reset flags in the RSTSRC register are indeterminate (PORSF is cleared by all other resets). Since all resets cause program execution to begin at the same location (0x0000), software can read the PORSF flag to determine if a power-up was the cause of reset. The contents of internal data memory should be assumed to be undefined after a power-on reset. VBAT VB AT VPOR See specification table for min/max voltages. t Logic HIGH RST TPORDelay TPORDelay Logic LOW Power-On Reset Power-On Reset Figure 18.2. Power-Fail Reset Timing Diagram 185 Rev. 1.4 C8051F93x-C8051F92x 18.2. Power-Fail (VDD/DC+ Supply Monitor) Reset C8051F93x-C8051F92x devices have a VDD/DC+ Supply Monitor that is enabled and selected as a reset source after each power-on or power-fail reset. When enabled and selected as a reset source, any power down transition or power irregularity that causes VDD/DC+ to drop below VRST will cause the RST pin to be driven low and the CIP-51 will be held in a reset state (see Figure 18.3). When VDD/DC+ returns to a level above VRST, the CIP-51 will be released from the reset state. After a power-fail reset, the PORSF flag reads 1, the contents of RAM invalid, and the VDD/DC+ supply monitor is enabled and selected as a reset source. The enable state of the VDD/DC+ supply monitor and its selection as a reset source is only altered by power-on and power-fail resets. For example, if the VDD/DC+ supply monitor is de-selected as a reset source and disabled by software, then a software reset is performed, the VDD/DC+ supply monitor will remain disabled and de-selected after the reset. In battery-operated systems, the contents of RAM can be preserved near the end of the battery’s usable life if the device is placed in sleep mode prior to a power-fail reset occurring. When the device is in sleep mode, the power-fail reset is automatically disabled and the contents of RAM are preserved as long as the VBAT supply does not fall below VPOR. A large capacitor can be used to hold the power supply voltage above VPOR while the user is replacing the battery. Upon waking from sleep mode, the enable and reset source select state of the VDD/DC+ supply monitor are restored to the value last set by the user. To allow software early notification that a power failure is about to occur, the VDDOK bit is cleared when the VDD/DC+ supply falls below the VWARN threshold. The VDDOK bit can be configured to generate an interrupt. See Section “12. Interrupt Handler” on page 136 for more details. volts Important Note: To protect the integrity of Flash contents, the VDD/DC+ supply monitor must be enabled and selected as a reset source if software contains routines which erase or write Flash memory. If the VDD/DC+ supply monitor is not enabled, any erase or write performed on Flash memory will cause a Flash Error device reset. VDD/DC+ V WARN V RST VBAT V POR t VDDOK SLEEP RST Active Mode Power-Fail Reset Sleep Mode RAM Retained - No Reset Note: W akeup signal required after new battery insertion Figure 18.3. Power-Fail Reset Timing Diagram Rev. 1.4 186 C8051F93x-C8051F92x Important Notes: • The Power-on Reset (POR) delay is not incurred after a VDD/DC+ supply monitor reset. See Section “4. Electrical Characteristics” on page 45 for complete electrical characteristics of the VDD/DC+ monitor. Software should take care not to inadvertently disable the VDD Monitor as a reset source when writing to RSTSRC to enable other reset sources or to trigger a software reset. All writes to RSTSRC should explicitly set PORSF to '1' to keep the VDD Monitor enabled as a reset source. The VDD/DC+ supply monitor must be enabled before selecting it as a reset source. Selecting the VDD/DC+ supply monitor as a reset source before it has stabilized may generate a system reset. In systems where this reset would be undesirable, a delay should be introduced between enabling the VDD/DC+ supply monitor and selecting it as a reset source. See Section “4. Electrical Characteristics” on page 45 for minimum VDD/DC+ Supply Monitor turn-on time. No delay should be introduced in systems where software contains routines that erase or write Flash memory. The procedure for enabling the VDD/DC+ supply monitor and selecting it as a reset source is shown below: • • 1. Enable the VDD/DC+ Supply Monitor (VDMEN bit in VDM0CN = 1). 2. Wait for the VDD/DC+ Supply Monitor to stabilize (optional). 3. Select the VDD/DC+ Supply Monitor as a reset source (PORSF bit in RSTSRC = 1). SFR Definition 18.1. VDM0CN: VDD/DC+ Supply Monitor Control Bit 7 6 5 4 3 2 Name VDMEN VDDSTAT VDDOK Reserved Reserved Reserved Type R/W R R R/W R/W Reset 1 Varies Varies 0 0 SFR Page = 0x0; SFR Address = 0xFF Bit Name 7 VDMEN 1 0 R/W R/W R/W 0 0 0 Function VDD/DC+ Supply Monitor Enable. This bit turns the VDD/DC+ supply monitor circuit on/off. The VDD/DC+ Supply Monitor cannot generate system resets until it is also selected as a reset source in register RSTSRC (SFR Definition 18.2). 0: VDD/DC+ Supply Monitor Disabled. 1: VDD/DC+ Supply Monitor Enabled. 6 VDDSTAT VDD/DC+ Supply Status. This bit indicates the current power supply status. 0: VDD/DC+ is at or below the VRST threshold. 1: VDD/DC+ is above the VRST threshold. 5 VDDOK VDD/DC+ Supply Status (Early Warning). This bit indicates the current power supply status. 0: VDD/DC+ is at or below the VWARN threshold. 1: VDD/DC+ is above the VWARN monitor threshold. 4:2 Reserved Reserved. Read = 000b. Must Write 000b. 1:0 Unused Unused. Read = 00b. Write = Don’t Care. 187 Rev. 1.4 C8051F93x-C8051F92x 18.3. External Reset The external RST pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the RST pin generates a reset; an external pullup and/or decoupling of the RST pin may be necessary to avoid erroneous noise-induced resets. See Table 4.4 for complete RST pin specifications. The external reset remains functional even when the device is in the low power suspend and sleep modes. The PINRSF flag (RSTSRC.0) is set on exit from an external reset. 18.4. Missing Clock Detector Reset The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a MCD reset, the MCDRSF flag (RSTSRC.2) will read 1, signifying the MCD as the reset source; otherwise, this bit reads 0. Writing a 1 to the MCDRSF bit enables the Missing Clock Detector; writing a 0 disables it. The missing clock detector reset is automatically disabled when the device is in the low power Suspend or Sleep mode. Upon exit from either low power state, the enabled/disabled state of this reset source is restored to its previous value. The state of the RST pin is unaffected by this reset. 18.5. Comparator0 Reset Comparator0 can be configured as a reset source by writing a 1 to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read 1 signifying Comparator0 as the reset source; otherwise, this bit reads 0. The Comparator0 reset source remains functional even when the device is in the low power suspend and sleep states as long as Comparator0 is also enabled as a wake-up source. The state of the RST pin is unaffected by this reset. 18.6. PCA Watchdog Timer Reset The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be used to prevent software from running out of control during a system malfunction. The PCA WDT function can be enabled or disabled by software as described in Section “26.4. Watchdog Timer Mode” on page 316; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to 1. The PCA Watchdog Timer reset source is automatically disabled when the device is in the low power Suspend or Sleep mode. Upon exit from either low power state, the enabled/disabled state of this reset source is restored to its previous value.The state of the RST pin is unaffected by this reset. Rev. 1.4 188 C8051F93x-C8051F92x 18.7. Flash Error Reset If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This may occur due to any of the following: • • • • • A Flash write or erase is attempted above user code space. This occurs when PSWE is set to 1 and a MOVX write operation targets an address above the Lock Byte address. A Flash read is attempted above user code space. This occurs when a MOVC operation targets an address above the Lock Byte address. A Program read is attempted above user code space. This occurs when user code attempts to branch to an address above the Lock Byte address. A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section “13.3. Security Options” on page 150). A Flash write or erase is attempted while the VDD Monitor is disabled. The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by this reset. 18.8. SmaRTClock (Real Time Clock) Reset The SmaRTClock can generate a system reset on two events: SmaRTClock Oscillator Fail or SmaRTClock Alarm. The SmaRTClock Oscillator Fail event occurs when the SmaRTClock Missing Clock Detector is enabled and the SmaRTClock clock is below approximately 20 kHz. A SmaRTClock alarm event occurs when the SmaRTClock Alarm is enabled and the SmaRTClock timer value matches the ALARMn registers. The SmaRTClock can be configured as a reset source by writing a 1 to the RTC0RE flag (RSTSRC.7). The SmaRTClock reset remains functional even when the device is in the low power Suspend or Sleep mode. The state of the RST pin is unaffected by this reset. 18.9. Software Reset Software may force a reset by writing a 1 to the SWRSF bit (RSTSRC.4). The SWRSF bit will read 1 following a software forced reset. The state of the RST pin is unaffected by this reset. 189 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 18.2. RSTSRC: Reset Source Bit 7 6 5 4 3 2 1 0 Name RTC0RE FERROR C0RSEF SWRSF WDTRSF MCDRSF PORSF PINRSF Type R/W R R/W R/W R R/W R/W R Reset Varies Varies Varies Varies Varies Varies Varies Varies SFR Page = 0x0; SFR Address = 0xEF. Bit Name Description Write Read 7 RTC0RE SmaRTClock Reset Enable and Flag Set to 1 if SmaRTClock 0: Disable SmaRTClock alarm or oscillator fail as a reset source. 1: Enable SmaRTClock as caused the last reset. a reset source. 6 FERROR Flash Error Reset Flag. N/A 5 C0RSEF Comparator0 Reset Enable and Flag. 0: Disable Comparator0 as Set to 1 if Comparator0 caused the last reset. a reset source. 1: Enable Comparator0 as a reset source. 4 SWRSF Writing a 1 forces a system reset. Software Reset Force and Flag. 3 WDTRSF Watchdog Timer Reset Flag. N/A 2 MCDRSF Missing Clock Detector (MCD) Enable and Flag. Set to 1 if Flash read/write/erase error caused the last reset. Set to 1 if last reset was caused by a write to SWRSF. Set to 1 if Watchdog Timer overflow caused the last reset. 0: Disable the MCD. Set to 1 if Missing Clock 1: Enable the MCD. Detector timeout caused The MCD triggers a reset the last reset. if a missing clock condition is detected. 1 PORSF Power-On / Power-Fail Reset Flag, and Power-Fail Reset Enable. 0: Disable the VDD/DC+ Supply Monitor as a reset source. 1: Enable the VDD/DC+ Supply Monitor as a reset source.3 Set to 1 anytime a poweron or VDD monitor reset occurs.2 0 PINRSF HW Pin Reset Flag. N/A Set to 1 if RST pin caused the last reset. Notes: 1. It is safe to use read-modify-write operations (ORL, ANL, etc.) to enable or disable specific interrupt sources. 2. If PORSF read back 1, the value read from all other bits in this register are indeterminate. 3. Writing a 1 to PORSF before the VDD/DC+ Supply Monitor is stabilized may generate a system reset. Rev. 1.4 190 C8051F93x-C8051F92x 19. Clocking Sources C8051F93x-C8051F92x devices include a programmable precision internal oscillator, an external oscillator drive circuit, a low power internal oscillator, and a SmaRTClock real time clock oscillator. The precision internal oscillator can be enabled/disabled and calibrated using the OSCICN and OSCICL registers, as shown in Figure 19.1. The external oscillator can be configured using the OSCXCN register. The low power internal oscillator is automatically enabled and disabled when selected and deselected as a clock source. SmaRTClock operation is described in the SmaRTClock oscillator chapter. The system clock (SYSCLK) can be derived from the precision internal oscillator, external oscillator, low power internal oscillator, or SmaRTClock oscillator. The global clock divider can generate a system clock that is 1, 2, 4, 8, 16, 32, 64, or 128 times slower that the selected input clock source. Oscillator electrical specifications can be found in the Electrical Specifications Chapter. OSCICL OSCICN CLKSEL VDD XTAL2 CLKSL1 CLKSL0 CLKRDY CLKDIV2 CLKDIV1 CLKDIV0 Option 3 IOSCEN IFRDY Option 2 XTAL2 EN Precision Internal Oscillator Option 1 Precision Internal Oscillator CLKRDY XTAL1 External Oscillator External Oscillator Drive Circuit 10MΩ n SYSCLK Low Power Internal Oscillator XTAL2 Clock Divider smaRTClock Oscillator XFCN2 XFCN1 XFCN0 XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 Option 4 XTAL2 Low Power Internal Oscillator SmaRTClock Oscillator OSCXCN Figure 19.1. Clocking Sources Block Diagram The proper way of changing the system clock when both the clock source and the clock divide value are being changed is as follows: If switching from a fast “undivided” clock to a slower “undivided” clock: a. Change the clock divide value. b. Poll for CLKRDY > 1. c. Change the clock source. If switching from a slow “undivided” clock to a faster “undivided” clock: a. Change the clock source. b. Change the clock divide value. c. Poll for CLKRDY > 1. Rev. 1.4 191 C8051F93x-C8051F92x 19.1. Programmable Precision Internal Oscillator All C8051F93x-C8051F92x devices include a programmable precision internal oscillator that may be selected as the system clock. OSCICL is factory calibrated to obtain a 24.5 MHz frequency. See Section “4. Electrical Characteristics” on page 45 for complete oscillator specifications. The precision oscillator supports a spread spectrum mode which modulates the output frequency in order to reduce the EMI generated by the system. When enabled (SSE = 1), the oscillator output frequency is modulated by a stepped triangle wave whose frequency is equal to the oscillator frequency divided by 384 (63.8 kHz using the factory calibration). The deviation from the nominal oscillator frequency is +0%, –1.6%, and the step size is typically 0.26% of the nominal frequency. When using this mode, the typical average oscillator frequency is lowered from 24.5 MHz to 24.3 MHz. 19.2. Low Power Internal Oscillator All C8051F93x-C8051F92x devices include a low power internal oscillator that defaults as the system clock after a system reset. The low power internal oscillator frequency is 20 MHz ± 10% and is automatically enabled when selected as the system clock and disabled when not in use. See Section “4. Electrical Characteristics” on page 45 for complete oscillator specifications. 19.3. External Oscillator Drive Circuit All C8051F93x-C8051F92x devices include an external oscillator circuit that may drive an external crystal, ceramic resonator, capacitor, or RC network. A CMOS clock may also provide a clock input. Figure 19.1 shows a block diagram of the four external oscillator options. The external oscillator is enabled and configured using the OSCXCN register. The external oscillator output may be selected as the system clock or used to clock some of the digital peripherals (e.g., timers, PCA, etc.). See the data sheet chapters for each digital peripheral for details. See Section “4. Electrical Characteristics” on page 45 for complete oscillator specifications. 19.3.1. External Crystal Mode If a crystal or ceramic resonator is used as the external oscillator, the crystal/resonator and a 10 MΩ resistor must be wired across the XTAL1 and XTAL2 pins as shown in Figure 19.1, Option 1. Appropriate loading capacitors should be added to XTAL1 and XTAL2, and both pins should be configured for analog I/O with the digital output drivers disabled. Figure 19.2 shows the external oscillator circuit for a 20 MHz quartz crystal with a manufacturer recommended load capacitance of 12.5 pF. Loading capacitors are "in series" as seen by the crystal and "in parallel" with the stray capacitance of the XTAL1 and XTAL2 pins. The total value of the each loading capacitor and the stray capacitance of each XTAL pin should equal 12.5pF x 2 = 25 pF. With a stray capacitance of 10 pF per pin, the 15 pF capacitors yield an equivalent series capacitance of 12.5 pF across the crystal. Note: The recommended load capacitance depends upon the crystal and the manufacturer. Refer to the crystal data sheet when completing these calculations. 192 Rev. 1.4 C8051F93x-C8051F92x 15 pF XTAL1 25 MHz 10 MΩ Ω XTAL2 15 pF Figure 19.2. 25 MHz 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. When using an external crystal, the external oscillator drive circuit must be configured by software for Crystal Oscillator Mode or Crystal Oscillator Mode with divide by 2 stage. The divide by 2 stage ensures that the clock derived from the external oscillator has a duty cycle of 50%. The External Oscillator Frequency Control value (XFCN) must also be specified based on the crystal frequency. The selection should be based on Table 19.1. For example, a 25 MHz crystal requires an XFCN setting of 111b. Table 19.1. Recommended XFCN Settings for Crystal Mode XFCN Crystal Frequency Bias Current Typical Supply Current (VDD = 2.4 V) 000 f ≤ 20 kHz 0.5 µA 3.0 µA, f = 32.768 kHz 001 20 kHz < f ≤ 58 kHz 1.5 µA 4.8 µA, f = 32.768 kHz 010 58 kHz < f ≤ 155 kHz 4.8 µA 9.6 µA, f = 32.768 kHz 011 155 kHz < f ≤ 415 kHz 14 µA 28 µA, f = 400 kHz 100 415 kHz < f ≤ 1.1 MHz 40 µA 71 µA, f = 400 kHz 101 1.1 MHz < f ≤ 3.1 MHz 120 µA 193 µA, f = 400 kHz 110 3.1 MHz < f ≤ 8.2 MHz 550 µA 940 µA, f = 8 MHz 111 8.2 MHz < f ≤ 25 MHz 2.6 mA 3.9 mA, f = 25 MHz When the crystal oscillator is first enabled, the external oscillator valid detector allows software to determine when the external system clock has stabilized. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure for starting the crystal is: 1. 2. 3. 4. Configure XTAL1 and XTAL2 for analog I/O and disable the digital output drivers. Configure and enable the external oscillator. Poll for XTLVLD > 1. Switch the system clock to the external oscillator. Rev. 1.4 193 C8051F93x-C8051F92x 19.3.2. External RC Mode If an RC network is used as the external oscillator, the circuit should be configured as shown in Figure 19.1, Option 2. The RC network should be added to XTAL2, and XTAL2 should be configured for analog I/O with the digital output drivers disabled. XTAL1 is not affected in RC mode. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. The resistor should be no smaller than 10kΩ. The oscillation frequency can be determined by the following equation: 3 1.23 × 10 f = ------------------------R×C where f = frequency of clock in MHz VDD = power supply voltage in Volts R = pull-up resistor value in kΩ C = capacitor value on the XTAL2 pin in pF 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. For example, if the frequency desired is 100 kHz, let R = 246 kΩ and C = 50 pF: 3 3 1.23 × 10 1.23 × 10 f = ------------------------- = ------------------------- = 100 kHz R×C 246 × 50 where f = frequency of clock in MHz VDD = power supply voltage in Volts R = pull-up resistor value in kΩ C = capacitor value on the XTAL2 pin in pF Referencing Table 19.2, the recommended XFCN setting is 010. Table 19.2. Recommended XFCN Settings for RC and C modes 194 XFCN Approximate Frequency Range (RC and C Mode) K Factor (C Mode) Typical Supply Current/ Actual Measured Frequency (C Mode, VDD = 2.4 V) 000 f ≤ 25 kHz K Factor = 0.87 3.0 µA, f = 11 kHz, C = 33 pF 001 25 kHz < f ≤ 50 kHz K Factor = 2.6 5.5 µA, f = 33 kHz, C = 33 pF 010 50 kHz < f ≤ 100 kHz K Factor = 7.7 13 µA, f = 98 kHz, C = 33 pF 011 100 kHz < f ≤ 200 kHz K Factor = 22 32 µA, f = 270 kHz, C = 33 pF 100 200 kHz < f ≤ 400 kHz K Factor = 65 82 µA, f = 310 kHz, C = 46 pF 101 400 kHz < f ≤ 800 kHz K Factor = 180 242 µA, f = 890 kHz, C = 46 pF 110 800 kHz < f ≤ 1.6 MHz K Factor = 664 1.0 mA, f = 2.0 MHz, C = 46 pF 111 1.6 MHz < f ≤ 3.2 MHz K Factor = 1590 4.6 mA, f = 6.8 MHz, C = 46 pF Rev. 1.4 C8051F93x-C8051F92x When the RC oscillator is first enabled, the external oscillator valid detector allows software to determine when oscillation has stabilized. The recommended procedure for starting the RC oscillator is: 1. 2. 3. 4. Configure XTAL2 for analog I/O and disable the digital output drivers. Configure and enable the external oscillator. Poll for XTLVLD > 1. Switch the system clock to the external oscillator. 19.3.3. External Capacitor Mode If a capacitor is used as the external oscillator, the circuit should be configured as shown in Figure 19.1, Option 3. The capacitor should be added to XTAL2, and XTAL2 should be configured for analog I/O with the digital output drivers disabled. XTAL1 is not affected in RC mode. The capacitor should be no greater than 100 pF; however, for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. The oscillation frequency and the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register can be determined by the following equation: KF f = --------------------C × V DD where f = frequency of clock in MHz VDD = power supply voltage in Volts R = pull-up resistor value in kΩ C = capacitor value on the XTAL2 pin in pF Below is an example of selecting the capacitor and finding the frequency of oscillation Assume VDD = 3.0 V and f = 150 kHz: KF f = --------------------C × V DD KF 0.150 MHz = ----------------C × 3.0 Since a frequency of roughly 150 kHz is desired, select the K Factor from Table 19.2 as KF = 22: 22 0.150 MHz = ----------------------C × 3.0 V 22 C = ----------------------------------------------0.150 MHz × 3.0 V C = 48.8 pF Therefore, the XFCN value to use in this example is 011 and C is approximately 50 pF. The recommended startup procedure for C mode is the same as RC mode. Rev. 1.4 195 C8051F93x-C8051F92x 19.3.4. External CMOS Clock Mode If an external CMOS clock is used as the external oscillator, the clock should be directly routed into XTAL2. The XTAL2 pin should be configured as a digital input. XTAL1 is not used in external CMOS clock mode. The external oscillator valid detector will always return zero when the external oscillator is configured to External CMOS Clock mode. 196 Rev. 1.4 C8051F93x-C8051F92x 19.4. Special Function Registers for Selecting and Configuring the System Clock The clocking sources on C8051F93x-C8051F92x devices are enabled and configured using the OSCICN, OSCICL, OSCXCN and the SmaRTClock internal registers. See Section “20. SmaRTClock (Real Time Clock)” on page 200 for SmaRTClock register descriptions. The system clock source for the MCU can be selected using the CLKSEL register. To minimize active mode current, the oneshot timer which sets Flash read time should by bypassed when the system clock is greater than 10 MHz. See the FLSCL register description for details. The clock selected as the system clock can be divided by 1, 2, 4, 8, 16, 32, 64, or 128. When switching between two clock divide values, the transition may take up to 128 cycles of the undivided clock source. The CLKRDY flag can be polled to determine when the new clock divide value has been applied. The clock divider must be set to "divide by 1" when entering suspend or sleep mode. The system clock source may also be switched on-the-fly. The switchover takes effect after one clock period of the slower oscillator. SFR Definition 19.1. CLKSEL: Clock Select Bit 7 6 5 4 3 2 Name CLKRDY Type R R/W R/W R/W R/W R/W R/W R/W Reset 0 0 1 1 0 1 0 0 CLKDIV[2:0] 1 0 CLKSEL[2:0] SFR Page = All Pages; SFR Address = 0xA9 Bit Name 7 CLKRDY 6:4 3 2:0 CLKDIV[2:0] CLKSEL[2:0] Function System Clock Divider Clock Ready Flag. 0: The selected clock divide setting has not been applied to the system clock. 1: The selected clock divide setting has been applied to the system clock. System Clock Divider Bits. Selects the clock division to be applied to the undivided system clock source. 000: System clock is divided by 1. 001: System clock is divided by 2. 010: System clock is divided by 4. 011: System clock is divided by 8. 100: System clock is divided by 16. 101: System clock is divided by 32. 110: System clock is divided by 64. 111: System clock is divided by 128. Unused. Read = 0b. Must Write 0b. System Clock Select. Selects the oscillator to be used as the undivided system clock source. 000: Precision Internal Oscillator. 001: External Oscillator. 011: SmaRTClock Oscillator. 100: Low Power Oscillator. All other values reserved. Rev. 1.4 197 C8051F93x-C8051F92x SFR Definition 19.2. OSCICN: Internal Oscillator Control Bit 7 6 5 4 3 Name IOSCEN IFRDY Type R/W R R/W R/W R/W Reset 0 0 0 0 1 2 1 0 R/W R/W R/W 1 1 1 Reserved[5:0] SFR Page = 0x0; SFR Address = 0xB2 Bit Name 7 IOSCEN Function Internal Oscillator Enable. 0: Internal oscillator disabled. 1: Internal oscillator enabled. 6 IFRDY Internal Oscillator Frequency Ready Flag. 0: Internal oscillator is not running at its programmed frequency. 1: Internal oscillator is running at its programmed frequency. 5:0 Reserved Reserved. Read = 001111b. Must Write 001111b. Note: It is recommended to use read-modify-write operations such as ORL and ANL to set or clear the enable bit of this register. SFR Definition 19.3. OSCICL: Internal Oscillator Calibration Bit 7 6 5 4 Name SSE Type R/W R/W R/W R/W Reset 0 Varies Varies Varies 3 2 1 0 R/W R/W R/W R/W Varies Varies Varies Varies OSCICL[6:0] SFR Page = 0x0; SFR Address = 0xB3 Bit Name 7 SSE Function Spread Spectrum Enable. 0: Spread Spectrum clock dithering disabled. 1: Spread Spectrum clock dithering enabled. 6:0 OSCICL Internal Oscillator Calibration. Factory calibrated to obtain a frequency of 24.5 MHz. Incrementing this register decreases the oscillator frequency and decrementing this register increases the oscillator frequency. The step size is approximately 1% of the calibrated frequency. The recommended calibration frequency range is between 16 and 24.5 MHz. 198 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 19.4. OSCXCN: External Oscillator Control Bit 7 6 Name XCLKVLD 5 4 XOSCMD[2:0] 3 2 Reserved 1 0 XFCN[2:0] Type R R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xB1 Bit 7 Name Function XCLKVLD External Oscillator Valid Flag. Provides External Oscillator status and is valid at all times for all modes of operation except External CMOS Clock Mode and External CMOS Clock Mode with divide by 2. In these modes, XCLKVLD always returns 0. 0: External Oscillator is unused or not yet stable. 1: External Oscillator is running and stable. 6:4 XOSCMD External Oscillator Mode Bits. Configures the external oscillator circuit to the selected mode. 00x: External Oscillator circuit disabled. 010: External CMOS Clock Mode. 011: External CMOS Clock Mode with divide by 2 stage. 100: RC Oscillator Mode. 101: Capacitor Oscillator Mode. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. 3 Reserved Reserved. Read = 0b. Must Write 0b. 2:0 XFCN External Oscillator Frequency Control Bits. Controls the external oscillator bias current. 000-111: See Table 19.1 on page 193 (Crystal Mode) or Table 19.2 on page 194 (RC or C Mode) for recommended settings. Rev. 1.4 199 C8051F93x-C8051F92x 20. SmaRTClock (Real Time Clock) C8051F93x-C8051F92x devices include an ultra low power 32-bit SmaRTClock Peripheral (Real Time Clock) with alarm. The SmaRTClock has a dedicated 32 kHz oscillator that can be configured for use with or without a crystal. No external resistor or loading capacitors are required. The on-chip loading capacitors are programmable to 16 discrete levels allowing compatibility with a wide range of crystals. The SmaRTClock can operate directly from a 0.9–3.6 V battery voltage and remains operational even when the device goes into its lowest power down mode. The SmaRTClock allows a maximum of 36 hour 32-bit independent time-keeping when used with a 32.768 kHz Watch Crystal. The SmaRTClock provides an Alarm and Missing SmaRTClock events, which could be used as reset or wakeup sources. See Section “18. Reset Sources” on page 184 and Section “14. Power Management” on page 159 for details on reset sources and low power mode wake-up sources, respectively. XTAL3 XTAL4 SmaRTClock Power/ Clock Mgmt Programmable Load Capacitors SmaRTClock Oscillator CIP-51 CPU 32-Bit SmaRTClock Timer SmaRTClock State Machine Wake-Up Interrupt Internal Registers CAPTUREn RTC0CN RTC0XCN RTC0XCF RTC0PIN ALARMn Interface Registers RTC0KEY RTC0ADR RTC0DAT Figure 20.1. SmaRTClock Block Diagram Rev. 1.4 200 C8051F93x-C8051F92x 20.1. SmaRTClock Interface The SmaRTClock Interface consists of three registers: RTC0KEY, RTC0ADR, and RTC0DAT. These interface registers are located on the CIP-51’s SFR map and provide access to the SmaRTClock internal registers listed in Table 20.1. The SmaRTClock internal registers can only be accessed indirectly through the SmaRTClock Interface. Table 20.1. SmaRTClock Internal Registers SmaRTClock SmaRTClock Address Register Register Name Description 0x00–0x03 CAPTUREn SmaRTClock Capture Registers Four Registers used for setting the 32-bit SmaRTClock timer or reading its current value. 0x04 RTC0CN SmaRTClock Control Register Controls the operation of the SmaRTClock State Machine. 0x05 RTC0XCN SmaRTClock Oscillator Control Register Controls the operation of the SmaRTClock Oscillator. 0x06 RTC0XCF SmaRTClock Oscillator Configuration Register Controls the value of the programmable oscillator load capacitance and enables/disables AutoStep. 0x07 RTC0PIN SmaRTClock Pin Configuration Register Forces XTAL3 and XTAL4 to be internally shorted. Note: This register also contains other reserved bits which should not be modified. 0x08–0x0B ALARMn SmaRTClock Alarm Registers Four registers used for setting or reading the 32-bit SmaRTClock alarm value. 20.1.1. SmaRTClock Lock and Key Functions The SmaRTClock Interface is protected with a lock and key function. The SmaRTClock Lock and Key Register (RTC0KEY) must be written with the correct key codes, in sequence, before writes and reads to RTC0ADR and RTC0DAT may be performed. The key codes are: 0xA5, 0xF1. There are no timing restrictions, but the key codes must be written in order. If the key codes are written out of order, the wrong codes are written, or an indirect register read or write is attempted while the interface is locked, the SmaRTClock interface will be disabled, and the RTC0ADR and RTC0DAT registers will become inaccessible until the next system reset. Once the SmaRTClock interface is unlocked, software may perform any number of accesses to the SmaRTClock registers until the interface is re-locked or the device is reset. Any write to RTC0KEY while the SmaRTClock interface is unlocked will re-lock the interface. Reading the RTC0KEY register at any time will provide the SmaRTClock Interface status and will not interfere with the sequence that is being written. The RTC0KEY register description in SFR Definition 20.1 lists the definition of each status code. 201 Rev. 1.4 C8051F93x-C8051F92x 20.1.2. Using RTC0ADR and RTC0DAT to Access SmaRTClock Internal Registers The SmaRTClock internal registers can be read and written using RTC0ADR and RTC0DAT. The RTC0ADR register selects the SmaRTClock internal register that will be targeted by subsequent reads or writes. Recommended instruction timing is provided in this section. If the recommended instruction timing is not followed, then BUSY (RTC0ADR.7) should be checked prior to each read or write operation to make sure the SmaRTClock Interface is not busy performing the previous read or write operation. A SmaRTClock Write operation is initiated by writing to the RTC0DAT register. Below is an example of writing to a SmaRTClock internal register. 1. Poll BUSY (RTC0ADR.7) until it returns 0 or follow recommended instruction timing. 2. Write 0x05 to RTC0ADR. This selects the internal RTC0CN register at SmaRTClock Address 0x05. 3. Write 0x00 to RTC0DAT. This operation writes 0x00 to the internal RTC0CN register. A SmaRTClock Read operation is initiated by setting the SmaRTClock Interface Busy bit. This transfers the contents of the internal register selected by RTC0ADR to RTC0DAT. The transferred data will remain in RTC0DAT until the next read or write operation. Below is an example of reading a SmaRTClock internal register. 1. Poll BUSY (RTC0ADR.7) until it returns 0 or follow recommended instruction timing. 2. Write 0x05 to RTC0ADR. This selects the internal RTC0CN register at SmaRTClock Address 0x05. 3. Write 1 to BUSY. This initiates the transfer of data from RTC0CN to RTC0DAT. 4. Poll BUSY (RTC0ADR.7) until it returns 0 or follow recommend instruction timing. 5. Read data from RTC0DAT. This data is a copy of the RTC0CN register. Note: The RTC0ADR and RTC0DAT registers will retain their state upon a device reset. 20.1.3. RTC0ADR Short Strobe Feature Reads and writes to indirect SmaRTClock registers normally take 7 system clock cycles. To minimize the indirect register access time, the Short Strobe feature decreases the read and write access time to 6 system clocks. The Short Strobe feature is automatically enabled on reset and can be manually enabled/disabled using the SHORT (RTC0ADR.4) control bit. Recommended Instruction Timing for a single register read with short strobe enabled: mov RTC0ADR, #095h nop nop nop mov A, RTC0DAT Recommended Instruction Timing for a single register write with short strobe enabled: mov RTC0ADR, #095h mov RTC0DAT, #000h nop Rev. 1.4 202 C8051F93x-C8051F92x 20.1.4. SmaRTClock Interface Autoread Feature When Autoread is enabled, each read from RTC0DAT initiates the next indirect read operation on the SmaRTClock internal register selected by RTC0ADR. Software should set the BUSY bit once at the beginning of each series of consecutive reads. Software should follow recommended instruction timing or check if the SmaRTClock Interface is busy prior to reading RTC0DAT. Autoread is enabled by setting AUTORD (RTC0ADR.6) to logic 1. 20.1.5. RTC0ADR Autoincrement Feature For ease of reading and writing the 32-bit CAPTURE and ALARM values, RTC0ADR automatically increments after each read or write to a CAPTUREn or ALARMn register. This speeds up the process of setting an alarm or reading the current SmaRTClock timer value. Autoincrement is always enabled. Recommended Instruction Timing for a multi-byte register read with short strobe and autoread enabled: mov nop nop nop mov nop nop mov nop nop mov nop nop mov RTC0ADR, #0d0h A, RTC0DAT A, RTC0DAT A, RTC0DAT A, RTC0DAT Recommended Instruction Timing for a multi-byte register write with short strobe enabled: mov mov nop mov nop mov nop mov nop 203 RTC0ADR, #010h RTC0DAT, #05h RTC0DAT, #06h RTC0DAT, #07h RTC0DAT, #08h Rev. 1.4 C8051F93x-C8051F92x SFR Definition 20.1. RTC0KEY: SmaRTClock Lock and Key Bit 7 6 5 4 3 Name RTC0ST[7:0] Type R/W Reset 0 0 0 SFR Page = 0x0; SFR Address = 0xAE Bit Name 7:0 RTC0ST 0 0 2 1 0 0 0 0 Function SmaRTClock Interface Lock/Key and Status. Locks/unlocks the SmaRTClock interface when written. Provides lock status when read. Read: 0x00: SmaRTClock Interface is locked. 0x01: SmaRTClock Interface is locked. First key code (0xA5) has been written, waiting for second key code. 0x02: SmaRTClock Interface is unlocked. First and second key codes (0xA5, 0xF1) have been written. 0x03: SmaRTClock Interface is disabled until the next system reset. Write: When RTC0ST = 0x00 (locked), writing 0xA5 followed by 0xF1 unlocks the SmaRTClock Interface. When RTC0ST = 0x01 (waiting for second key code), writing any value other than the second key code (0xF1) will change RTC0STATE to 0x03 and disable the SmaRTClock Interface until the next system reset. When RTC0ST = 0x02 (unlocked), any write to RTC0KEY will lock the SmaRTClock Interface. When RTC0ST = 0x03 (disabled), writes to RTC0KEY have no effect. Rev. 1.4 204 C8051F93x-C8051F92x SFR Definition 20.2. RTC0ADR: SmaRTClock Address Bit 7 6 Name BUSY AUTORD Type R/W R/W Reset 0 0 5 4 3 SHORT ADDR[3:0] R R/W R/W 0 0 0 SFR Page = 0x0; SFR Address = 0xAC Bit Name 7 BUSY 2 0 1 0 0 0 Function SmaRTClock Interface Busy Indicator. Indicates SmaRTClock interface status. Writing 1 to this bit initiates an indirect read. 6 AUTORD SmaRTClock Interface Autoread Enable. Enables/disables Autoread. 0: Autoread Disabled. 1: Autoread Enabled. 5 Unused Unused. Read = 0b; Write = Don’t Care. 4 SHORT Short Strobe Enable. Enables/disables the Short Strobe Feature. 0: Short Strobe disabled. 1: Short Strobe enabled. 3:0 ADDR[3:0] SmaRTClock Indirect Register Address. Sets the currently selected SmaRTClock register. See Table 20.1 for a listing of all SmaRTClock indirect registers. Note: The ADDR bits increment after each indirect read/write operation that targets a CAPTUREn or ALARMn internal SmaRTClock register. SFR Definition 20.3. RTC0DAT: SmaRTClock Data Bit 7 6 5 4 3 Name RTC0DAT[7:0] Type R/W Reset 0 0 0 0 SFR Page= 0x0; SFR Address = 0xAD Bit Name 7:0 0 2 1 0 0 0 0 Function RTC0DAT SmaRTClock Data Bits. Holds data transferred to/from the internal SmaRTClock register selected by RTC0ADR. Note: Read-modify-write instructions (orl, anl, etc.) should not be used on this register. 205 Rev. 1.4 C8051F93x-C8051F92x 20.2. SmaRTClock Clocking Sources The SmaRTClock peripheral is clocked from its own timebase, independent of the system clock. The SmaRTClock timebase is derived from the SmaRTClock oscillator circuit, which has two modes of operation: Crystal Mode, and Self-Oscillate Mode. The oscillation frequency is 32.768 kHz in Crystal Mode and can be programmed in the range of 10 kHz to 40 kHz in Self-Oscillate Mode. The frequency of the SmaRTClock oscillator can be measured with respect to another oscillator using an on-chip timer. See Section “25. Timers” on page 283 for more information on how this can be accomplished. Note: The SmaRTClock timebase can be selected as the system clock and routed to a port pin. See Section “19. Clocking Sources” on page 191 for information on selecting the system clock source and Section “21. Port Input/Output” on page 216 for information on how to route the system clock to a port pin. 20.2.1. Using the SmaRTClock Oscillator with a Crystal or External CMOS Clock When using crystal mode, a 32.768 kHz crystal should be connected between XTAL3 and XTAL4. No other external components are required. The following steps show how to start the SmaRTClock crystal oscillator in software: 1. Set SmaRTClock to Crystal Mode (XMODE = 1). 2. Disable Automatic Gain Control (AGCEN) and enable Bias Doubling (BIASX2) for fast crystal startup. 3. Set the desired loading capacitance (RTC0XCF). 4. Enable power to the SmaRTClock oscillator circuit (RTC0EN = 1). 5. Wait 20 ms. 6. Poll the SmaRTClock Clock Valid Bit (CLKVLD) until the crystal oscillator stabilizes. 7. Poll the SmaRTClock Load Capacitance Ready Bit (LOADRDY) until the load capacitance reaches its programmed value. 8. Enable Automatic Gain Control (AGCEN) and disable Bias Doubling (BIASX2) for maximum power savings. 9. Enable the SmaRTClock missing clock detector. 10. Wait 2 ms. 11. Clear the PMU0CF wake-up source flags. In crystal mode, the SmaRTClock oscillator may be driven by an external CMOS clock. The CMOS clock should be applied to XTAL3. XTAL4 should be left floating. The input low voltage (VIL) and input high voltage (VIH) for XTAL3 when used with an external CMOS clock are 0.1 and 0.8 V, respectively. The SmaRTClock oscillator should be configured to its lowest bias setting with AGC disabled. The CLKVLD bit is indeterminate when using a CMOS clock, however, the OSCFAIL bit may be checked 2 ms after SmaRTClock oscillator is powered on to ensure that there is a valid clock on XTAL3. 20.2.2. Using the SmaRTClock Oscillator in Self-Oscillate Mode When using Self-Oscillate Mode, the XTAL3 and XTAL4 pins should be shorted together. The RTC0PIN register can be used to internally short XTAL3 and XTAL4. The following steps show how to configure SmaRTClock for use in Self-Oscillate Mode: 1. Set SmaRTClock to Self-Oscillate Mode (XMODE = 0). 2. Set the desired oscillation frequency: For oscillation at about 20 kHz, set BIASX2 = 0. For oscillation at about 40 kHz, set BIASX2 = 1. 3. The oscillator starts oscillating instantaneously. 4. Fine tune the oscillation frequency by adjusting the load capacitance (RTC0XCF). Rev. 1.4 206 C8051F93x-C8051F92x 20.2.3. Programmable Load Capacitance The programmable load capacitance has 16 values to support crystal oscillators with a wide range of recommended load capacitance. If Automatic Load Capacitance Stepping is enabled, the crystal load capacitors start at the smallest setting to allow a fast startup time, then slowly increase the capacitance until the final programmed value is reached. The final programmed loading capacitor value is specified using the LOADCAP bits in the RTC0XCF register. The LOADCAP setting specifies the amount of on-chip load capacitance and does not include any stray PCB capacitance. Once the final programmed loading capacitor value is reached, the LOADRDY flag will be set by hardware to logic 1. When using the SmaRTClock oscillator in Self-Oscillate mode, the programmable load capacitance can be used to fine tune the oscillation frequency. In most cases, increasing the load capacitor value will result in a decrease in oscillation frequency. Table 20.2 shows the crystal load capacitance for various settings of LOADCAP. Table 20.2. SmaRTClock Load Capacitance Settings 207 LOADCAP Crystal Load Capacitance Equivalent Capacitance seen on XTAL3 and XTAL4 0000 4.0 pF 8.0 pF 0001 4.5 pF 9.0 pF 0010 5.0 pF 10.0 pF 0011 5.5 pF 11.0 pF 0100 6.0 pF 12.0 pF 0101 6.5 pF 13.0 pF 0110 7.0 pF 14.0 pF 0111 7.5 pF 15.0 pF 1000 8.0 pF 16.0 pF 1001 8.5 pF 17.0 pF 1010 9.0 pF 18.0 pF 1011 9.5 pF 19.0 pF 1100 10.5 pF 21.0 pF 1101 11.5 pF 23.0 pF 1110 12.5 pF 25.0 pF 1111 13.5 pF 27.0 pF Rev. 1.4 C8051F93x-C8051F92x 20.2.4. Automatic Gain Control (Crystal Mode Only) and SmaRTClock Bias Doubling Automatic Gain Control allows the SmaRTClock oscillator to trim the oscillation amplitude of a crystal in order to achieve the lowest possible power consumption. Automatic Gain Control automatically detects when the oscillation amplitude has reached a point where it safe to reduce the drive current, therefore, it may be enabled during crystal startup. It is recommended to enable Automatic Gain Control in most systems which use the SmaRTClock oscillator in Crystal Mode. The following are recommended crystal specifications and operating conditions when Automatic Gain Control is enabled: • • • • ESR < 50 kΩ Load Capacitance < 10 pF Supply Voltage < 3.0 V Temperature > –20 °C When using Automatic Gain Control, it is recommended to perform an oscillation robustness test to ensure that the chosen crystal will oscillate under the worst case condition to which the system will be exposed. The worst case condition that should result in the least robust oscillation is at the following system conditions: lowest temperature, highest supply voltage, highest ESR, highest load capacitance, and lowest bias current (AGC enabled, Bias Double Disabled). To perform the oscillation robustness test, the SmaRTClock oscillator should be enabled and selected as the system clock source. Next, the SYSCLK signal should be routed to a port pin configured as a push-pull digital output. The positive duty cycle of the output clock can be used as an indicator of oscillation robustness. As shown in Figure 20.2, duty cycles less than 55% indicate a robust oscillation. As the duty cycle approaches 60%, oscillation becomes less reliable and the risk of clock failure increases. Increasing the bias current (by disabling AGC) will always improve oscillation robustness and will reduce the output clock’s duty cycle. This test should be performed at the worst case system conditions, as results at very low temperatures or high supply voltage will vary from results taken at room temperature or low supply voltage. Safe Operating Zone 25% Low Risk of Clock Failure 55% High Risk of Clock Failure 60% Duty Cycle Figure 20.2. Interpreting Oscillation Robustness (Duty Cycle) Test Results As an alternative to performing the oscillation robustness test, Automatic Gain Control may be disabled at the cost of increased power consumption (approximately 200 nA). Disabling Automatic Gain Control will provide the crystal oscillator with higher immunity against external factors which may lead to clock failure. Automatic Gain Control must be disabled if using the SmaRTClock oscillator in self-oscillate mode. Rev. 1.4 208 C8051F93x-C8051F92x Table 20.3 shows a summary of the oscillator bias settings. The SmaRTClock Bias Doubling feature allows the self-oscillation frequency to be increased (almost doubled) and allows a higher crystal drive strength in crystal mode. High crystal drive strength is recommended when the crystal is exposed to poor environmental conditions such as excessive moisture. SmaRTClock Bias Doubling is enabled by setting BIASX2 (RTC0XCN.5) to 1. . Table 20.3. SmaRTClock Bias Settings Mode Setting Power Consumption Crystal Bias Double Off, AGC On Lowest 600 nA Bias Double Off, AGC Off Low 800 nA Bias Double On, AGC On High Bias Double On, AGC Off Highest Bias Double Off Low Bias Double On High Self-Oscillate 209 Rev. 1.4 C8051F93x-C8051F92x 20.2.5. Missing SmaRTClock Detector The missing SmaRTClock detector is a one-shot circuit enabled by setting MCLKEN (RTC0CN.6) to 1. When the SmaRTClock Missing Clock Detector is enabled, OSCFAIL (RTC0CN.5) is set by hardware if SmaRTClock oscillator remains high or low for more than 100 µs. A SmaRTClock Missing Clock detector timeout can trigger an interrupt, wake the device from a low power mode, or reset the device. See Section “12. Interrupt Handler” on page 136, Section “14. Power Management” on page 159, and Section “18. Reset Sources” on page 184 for more information. Note: The SmaRTClock Missing Clock Detector should be disabled when making changes to the oscillator settings in RTC0XCN. 20.2.6. SmaRTClock Oscillator Crystal Valid Detector The SmaRTClock oscillator crystal valid detector is an oscillation amplitude detector circuit used during crystal startup to determine when oscillation has started and is nearly stable. The output of this detector can be read from the CLKVLD bit (RTX0XCN.4). Notes: • • The CLKVLD bit has a blanking interval of 2 ms. During the first 2 ms after turning on the crystal oscillator, the output of CLKVLD is not valid. This SmaRTClock crystal valid detector (CLKVLD) is not intended for detecting an oscillator failure. The missing SmaRTClock detector (CLKFAIL) should be used for this purpose. 20.3. SmaRTClock Timer and Alarm Function The SmaRTClock timer is a 32-bit counter that, when running (RTC0TR = 1), is incremented every SmaRTClock oscillator cycle. The timer has an alarm function that can be set to generate an interrupt, wake the device from a low power mode, or reset the device at a specific time. See Section “12. Interrupt Handler” on page 136, Section “14. Power Management” on page 159, and Section “18. Reset Sources” on page 184 for more information. The SmaRTClock timer includes an Auto Reset feature, which automatically resets the timer to zero one SmaRTClock cycle after an alarm occurs. When using Auto Reset, the Alarm match value should always be set to 1 count less than the desired match value. Auto Reset can be enabled by writing a 1 to ALRM (RTC0CN.2). 20.3.1. Setting and Reading the SmaRTClock Timer Value The 32-bit SmaRTClock timer can be set or read using the six CAPTUREn internal registers. Note that the timer does not need to be stopped before reading or setting its value. The following steps can be used to set the timer value: 1. Write the desired 32-bit set value to the CAPTUREn registers. 2. Write 1 to RTC0SET. This will transfer the contents of the CAPTUREn registers to the SmaRTClock timer. 3. Operation is complete when RTC0SET is cleared to 0 by hardware. The following steps can be used to read the current timer value: 1. Write 1 to RTC0CAP. This will transfer the contents of the timer to the CAPTUREn registers. 2. Poll RTC0CAP until it is cleared to 0 by hardware. 3. A snapshot of the timer value can be read from the CAPTUREn registers Rev. 1.4 210 C8051F93x-C8051F92x 20.3.2. Setting a SmaRTClock Alarm The SmaRTClock alarm function compares the 32-bit value of SmaRTClock Timer to the value of the ALARMn registers. An alarm event is triggered if the SmaRTClock timer is equal to the ALARMn registers. If Auto Reset is enabled, the 32-bit timer will be cleared to zero one SmaRTClock cycle after the alarm event. The SmaRTClock alarm event can be configured to reset the MCU, wake it up from a low power mode, or generate an interrupt. See Section “12. Interrupt Handler” on page 136, Section “14. Power Management” on page 159, and Section “18. Reset Sources” on page 184 for more information. The following steps can be used to set up a SmaRTClock Alarm: 1. Disable SmaRTClock Alarm Events (RTC0AEN = 0). 2. Set the ALARMn registers to the desired value. 3. Enable SmaRTClock Alarm Events (RTC0AEN = 1). Notes: • • • The ALRM bit, which is used as the SmaRTClock Alarm Event flag, is cleared by disabling SmaRTClock Alarm Events (RTC0AEN = 0). If AutoReset is disabled, disabling (RTC0AEN = 0) then Re-enabling Alarm Events (RTC0AEN = 1) after a SmaRTClock Alarm without modifying ALARMn registers will automatically schedule the next alarm after 2^32 SmaRTClock cycles (approximately 36 hours using a 32.768 kHz crystal). The SmaRTClock Alarm Event flag will remain asserted for a maximum of one SmaRTClock cycle. See Section “14. Power Management” on page 159 for information on how to capture a SmaRTClock Alarm event using a flag which is not automatically cleared by hardware. 20.3.3. Software Considerations for using the SmaRTClock Timer and Alarm The SmaRTClock timer and alarm have two operating modes to suit varying applications. The two modes are described below: Mode 1: The first mode uses the SmaRTClock timer as a perpetual timebase which is never reset to zero. Every 36 hours, the timer is allowed to overflow without being stopped or disrupted. The alarm interval is software managed and is added to the ALRMn registers by software after each alarm. This allows the alarm match value to always stay ahead of the timer by one software managed interval. If software uses 32-bit unsigned addition to increment the alarm match value, then it does not need to handle overflows since both the timer and the alarm match value will overflow in the same manner. This mode is ideal for applications which have a long alarm interval (e.g. 24 or 36 hours) and/or have a need for a perpetual timebase. An example of an application that needs a perpetual timebase is one whose wake-up interval is constantly changing. For these applications, software can keep track of the number of timer overflows in a 16-bit variable, extending the 32-bit (36 hour) timer to a 48-bit (272 year) perpetual timebase. Mode 2: The second mode uses the SmaRTClock timer as a general purpose up counter which is auto reset to zero by hardware after each alarm. The alarm interval is managed by hardware and stored in the ALRMn registers. Software only needs to set the alarm interval once during device initialization. After each alarm, software should keep a count of the number of alarms that have occurred in order to keep track of time. This mode is ideal for applications that require minimal software intervention and/or have a fixed alarm interval. This mode is the most power efficient since it requires less CPU time per alarm. 211 Rev. 1.4 C8051F93x-C8051F92x Internal Register Definition 20.4. RTC0CN: SmaRTClock Control Bit 7 6 5 4 3 2 Name RTC0EN MCLKEN OSCFAIL RTC0TR RTC0AEN ALRM Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 Varies 0 0 0 0 0 SmaRTClock Address = 0x04 Bit Name 7 RTC0EN 1 0 RTC0SET RTC0CAP Function SmaRTClock Enable. Enables/disables the SmaRTClock oscillator and associated bias currents. 0: SmaRTClock oscillator disabled. 1: SmaRTClock oscillator enabled. 6 MCLKEN Missing SmaRTClock Detector Enable. Enables/disables the missing SmaRTClock detector. 0: Missing SmaRTClock detector disabled. 1: Missing SmaRTClock detector enabled. 5 OSCFAIL SmaRTClock Oscillator Fail Event Flag. Set by hardware when a missing SmaRTClock detector timeout occurs. Must be cleared by software. The value of this bit is not defined when the SmaRTClock oscillator is disabled. 4 RTC0TR SmaRTClock Timer Run Control. Controls if the SmaRTClock timer is running or stopped (holds current value). 0: SmaRTClock timer is stopped. 1: SmaRTClock timer is running. 3 RTC0AEN SmaRTClock Alarm Enable. Enables/disables the SmaRTClock alarm function. Also clears the ALRM flag. 0: SmaRTClock alarm disabled. 1: SmaRTClock alarm enabled. 2 ALRM Read: 0: SmaRTClock alarm event flag is de-asserted. 1: SmaRTClock alarm Reads return the state of the event flag is asserted. alarm event flag. SmaRTClock Alarm Event Flag and Auto Reset Enable Write: 0: Disable Auto Reset. 1: Enable Auto Reset. Writes enable/disable the Auto Reset function. 1 RTC0SET SmaRTClock Timer Set. Writing 1 initiates a SmaRTClock timer set operation. This bit is cleared to 0 by hardware to indicate that the timer set operation is complete. 0 RTC0CAP SmaRTClock Timer Capture. Writing 1 initiates a SmaRTClock timer capture operation. This bit is cleared to 0 by hardware to indicate that the timer capture operation is complete. Note: The ALRM flag will remain asserted for a maximum of one SmaRTClock cycle. See Section “Power Management” on page 159 for information on how to capture a SmaRTClock Alarm event using a flag which is not automatically cleared by hardware. Rev. 1.4 212 C8051F93x-C8051F92x Internal Register Definition 20.5. RTC0XCN: SmaRTClock Oscillator Control Bit 7 6 5 4 3 2 1 0 Name AGCEN XMODE BIASX2 CLKVLD Type R/W R/W R/W R R R R R Reset 0 0 0 0 0 0 0 0 SmaRTClock Address = 0x05 Bit Name 7 AGCEN Function SmaRTClock Oscillator Automatic Gain Control (AGC) Enable. 0: AGC disabled. 1: AGC enabled. 6 XMODE SmaRTClock Oscillator Mode. Selects Crystal or Self Oscillate Mode. 0: Self-Oscillate Mode selected. 1: Crystal Mode selected. 5 BIASX2 SmaRTClock Oscillator Bias Double Enable. Enables/disables the Bias Double feature. 0: Bias Double disabled. 1: Bias Double enabled. 4 CLKVLD SmaRTClock Oscillator Crystal Valid Indicator. Indicates if oscillation amplitude is sufficient for maintaining oscillation. 0: Oscillation has not started or oscillation amplitude is too low to maintain oscillation. 1: Sufficient oscillation amplitude detected. 3:0 Unused Unused. Read = 0000b; Write = Don’t Care. 213 Rev. 1.4 C8051F93x-C8051F92x Internal Register Definition 20.6. RTC0XCF: SmaRTClock Oscillator Configuration Bit 7 6 Name AUTOSTP 5 4 3 LOADRDY R/W R R R Reset 0 0 0 0 0 R/W Varies SmaRTClock Address = 0x06 Bit Name AUTOSTP 1 LOADCAP Type 7 2 Varies Varies Varies Function Automatic Load Capacitance Stepping Enable. Enables/disables automatic load capacitance stepping. 0: Load capacitance stepping disabled. 1: Load capacitance stepping enabled. 6 LOADRDY Load Capacitance Ready Indicator. Set by hardware when the load capacitance matches the programmed value. 0: Load capacitance is currently stepping. 1: Load capacitance has reached it programmed value. 5:4 Unused Unused. Read = 00b; Write = Don’t Care. 3:0 LOADCAP Load Capacitance Programmed Value. Holds the user’s desired value of the load capacitance. See Table 20.2 on page 207. Internal Register Definition 20.7. RTC0PIN: SmaRTClock Pin Configuration Bit 7 6 5 4 Name RTC0PIN Type W Reset 0 1 1 0 SmaRTClock Address = 0x07 Bit Name 7:0 3 2 1 0 0 1 1 1 Function RTC0PIN SmaRTClock Pin Configuration. Writing 0xE7 to this register forces XTAL3 and XTAL4 to be internally shorted for use with Self Oscillate Mode. Writing 0x67 returns XTAL3 and XTAL4 to their normal configuration. Rev. 1.4 214 C8051F93x-C8051F92x Internal Register Definition 20.8. CAPTUREn: SmaRTClock Timer Capture Bit 7 6 5 4 3 2 1 0 CAPTURE[31:0] Name Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SmaRTClock Addresses: CAPTURE0 = 0x00; CAPTURE1 = 0x01; CAPTURE2 =0x02; CAPTURE3: 0x03. Bit Name Function 7:0 CAPTURE[31:0] SmaRTClock Timer Capture. These 4 registers (CAPTURE3–CAPTURE0) are used to read or set the 32-bit SmaRTClock timer. Data is transferred to or from the SmaRTClock timer when the RTC0SET or RTC0CAP bits are set. Note: The least significant bit of the timer capture value is in CAPTURE0.0. Internal Register Definition 20.9. ALARMn: SmaRTClock Alarm Programmed Value Bit 7 6 5 4 3 2 1 0 ALARM[31:0] Name Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SmaRTClock Addresses: ALARM0 = 0x08; ALARM1 = 0x09; ALARM2 = 0x0A; ALARM3 = 0x0B Bit Name Function 7:0 ALARM[31:0] SmaRTClock Alarm Programmed Value. These 4 registers (ALARM3–ALARM0) are used to set an alarm event for the SmaRTClock timer. The SmaRTClock alarm should be disabled (RTC0AEN=0) when updating these registers. Note: The least significant bit of the alarm programmed value is in ALARM0.0. 215 Rev. 1.4 C8051F93x-C8051F92x 21. Port Input/Output Digital and analog resources are available through 24 I/O pins (C8051F930/20) or 16 I/O pins (C8051F931/21). Port pins are organized as three byte-wide ports. Port pins P0.0–P2.6 can be defined as digital or analog I/O. Digital I/O pins can be assigned to one of the internal digital resources or used as general purpose I/O (GPIO). Analog I/O pins are used by the internal analog resources. P2.7 can be used as GPIO and is shared with the C2 Interface Data signal (C2D). See Section “27. C2 Interface” on page 324 for more details. The designer has complete control over which digital and analog functions are assigned to individual port pins, limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. See Section 21.3 for more information on the Crossbar. All Port I/Os are 5 V tolerant when used as digital inputs or open-drain outputs. For Port I/Os configured as push-pull outputs, current is sourced from the VDD/DC+ supply. Port I/Os used for analog functions can operate up to the VDD/DC+ supply voltage. See Section 21.1 for more information on Port I/O operating modes and the electrical specifications chapter for detailed electrical specifications. XBR0, XBR1, XBR2, PnSKIP Registers Port Match P0MASK, P0MAT P1MASK, P1MAT External Interrupts EX0 and EX1 Priority Decoder Highest Priority UART 4 (Internal Digital Signals) SPI0 SPI1 P0.0 2 SMBus CP0 CP1 Outputs Digital Crossbar 8 4 P1.0 8 P1 I/O Cells 7 T0, T1 P0 I/O Cells P0.7 SYSCLK PCA Lowest Priority PnMDOUT, PnMDIN Registers 2 P1.7 2 8 (Port Latches) P0 P2.0 8 (P0.0-P0.7) P2 I/O Cell 8 P1 (P1.0-P1.7) To EMIF 8 P2 (P2.0-P2.7) P1.6 To Analog Peripherals (ADC0, CP0, and CP1 inputs, VREF, IREF0, AGND) P2.6 P2.7 P1.7–2.6 only available on 32-pin devices P2.7 is available on all devices Figure 21.1. Port I/O Functional Block Diagram Rev. 1.4 216 C8051F93x-C8051F92x 21.1. Port I/O Modes of Operation Port pins P0.0–P2.6 use the Port I/O cell shown in Figure 21.2. Each Port I/O cell can be configured by software for analog I/O or digital I/O using the PnMDIN registers. On reset, all Port I/O cells default to a digital high impedance state with weak pull-ups enabled. 21.1.1. Port Pins Configured for Analog I/O Any pins to be used as Comparator or ADC input, external oscillator input/output, or AGND, VREF, or Current Reference output should be configured for analog I/O (PnMDIN.n = 0). When a pin is configured for analog I/O, its weak pullup and digital receiver are disabled. In most cases, software should also disable the digital output drivers. Port pins configured for analog I/O will always read back a value of 0 regardless of the actual voltage on the pin. Configuring pins as analog I/O saves power and isolates the Port pin from digital interference. Port pins configured as digital inputs may still be used by analog peripherals; however, this practice is not recommended and may result in measurement errors. 21.1.2. Port Pins Configured For Digital I/O Any pins to be used by digital peripherals (UART, SPI, SMBus, etc.), external digital event capture functions, or as GPIO should be configured as digital I/O (PnMDIN.n = 1). For digital I/O pins, one of two output modes (push-pull or open-drain) must be selected using the PnMDOUT registers. Push-pull outputs (PnMDOUT.n = 1) drive the Port pad to the VDD/DC+ or GND supply rails based on the output logic value of the Port pin. Open-drain outputs have the high side driver disabled; therefore, they only drive the Port pad to GND when the output logic value is 0 and become high impedance inputs (both high and low drivers turned off) when the output logic value is 1. When a digital I/O cell is placed in the high impedance state, a weak pull-up transistor pulls the Port pad to the VDD/DC+ supply voltage to ensure the digital input is at a defined logic state. Weak pull-ups are disabled when the I/O cell is driven to GND to minimize power consumption and may be globally disabled by setting WEAKPUD to 1. The user must ensure that digital I/O are always internally or externally pulled or driven to a valid logic state. Port pins configured for digital I/O always read back the logic state of the Port pad, regardless of the output logic value of the Port pin. WEAKPUD (Weak Pull-Up Disable) PnMDOUT.x (1 for push-pull) (0 for open-drain) VDD/DC+ XBARE (Crossbar Enable) (WEAK) PORT PAD Pn.x – Output Logic Value (Port Latch or Crossbar) PnMDIN.x (1 for digital) (0 for analog) To/From Analog Peripheral GND Pn.x – Input Logic Value (Reads 0 when pin is configured as an analog I/O) Figure 21.2. Port I/O Cell Block Diagram 217 VDD/DC+ Rev. 1.4 C8051F93x-C8051F92x 21.1.3. Interfacing Port I/O to 5 V and 3.3 V Logic All Port I/O configured for digital, open-drain operation are capable of interfacing to digital logic operating at a supply voltage higher than 4.5 V and less than 5.25 V. When the supply voltage is in the range of 1.8 to 2.2 V, the I/O may also interface to digital logic operating between 3.0 to 3.6 V if the input signal frequency is less than 12.5 MHz or less than 25 MHz if the signal rise time (10% to 90%) is less than 1.2 ns. When operating at a supply voltage above 2.2 V, the device should not interface to 3.3 V logic; however, interfacing to 5 V logic is permitted. An external pull-up resistor to the higher supply voltage is typically required for most systems. Important Notes: • • • When interfacing to a signal that is between 4.5 and 5.25 V, the maximum clock frequency that may be input on a GPIO pin is 12.5 MHz. The exception to this rule is when routing an external CMOS clock to P0.3, in which case, a signal up to 25 MHz is valid as long as the rise time (10% to 90%) is shorter than 1.8 ns. When the supply voltage is less than 2.2 V and interfacing to a signal that is between 3.0 and 3.6 V, the maximum clock frequency that may be input on a GPIO pin is 3.125 MHz. The exception to this rule is when routing an external CMOS clock to P0.3, in which case, a signal up to 25 MHz is valued as long as the rise time (10% to 90%) is shorter than 1.2 ns. In a multi-voltage interface, the external pull-up resistor should be sized to allow a current of at least 150 μA to flow into the Port pin when the supply voltage is between (VDD/DC+ plus 0.4 V) and (VDD/DC+ plus 1.0 V). Once the Port pad voltage increases beyond this range, the current flowing into the Port pin is minimal. These guidelines only apply to multi-voltage interfaces. Port I/Os may always interface to digital logic operating at the same supply voltage. 21.1.4. Increasing Port I/O Drive Strength Port I/O output drivers support a high and low drive strength; the default is low drive strength. The drive strength of a Port I/O can be configured using the PnDRV registers. See Section “4. Electrical Characteristics” on page 45 for the difference in output drive strength between the two modes. 21.2. Assigning Port I/O Pins to Analog and Digital Functions Port I/O pins P0.0–P2.6 can be assigned to various analog, digital, and external interrupt functions. The Port pins assuaged to analog functions should be configured for analog I/O and Port pins assuaged to digital or external interrupt functions should be configured for digital I/O. 21.2.1. Assigning Port I/O Pins to Analog Functions Table 21.1 shows all available analog functions that need Port I/O assignments. Port pins selected for these analog functions should have their digital drivers disabled (PnMDOUT.n = 0 and Port Latch = 1) and their corresponding bit in PnSKIP set to 1. This reserves the pin for use by the analog function and does not allow it to be claimed by the Crossbar. Table 21.1 shows the potential mapping of Port I/O to each analog function. Table 21.1. Port I/O Assignment for Analog Functions Analog Function Potentially Assignable Port Pins SFR(s) used for Assignment ADC Input P0.0–P2.6 ADC0MX, PnSKIP Comparator0 Input P0.0–P2.6 CPT0MX, PnSKIP Rev. 1.4 218 C8051F93x-C8051F92x Table 21.1. Port I/O Assignment for Analog Functions 219 Analog Function Potentially Assignable Port Pins SFR(s) used for Assignment Comparator1 Input P0.0–P2.6 CPT1MX, PnSKIP Voltage Reference (VREF0) P0.0 REF0CN, PnSKIP Analog Ground Reference (AGND) P0.1 REF0CN, PnSKIP Current Reference (IREF0) P0.7 IREF0CN, PnSKIP External Oscillator Input (XTAL1) P0.2 OSCXCN, PnSKIP External Oscillator Output (XTAL2) P0.3 OSCXCN, PnSKIP Rev. 1.4 C8051F93x-C8051F92x 21.2.2. Assigning Port I/O Pins to Digital Functions Any Port pins not assigned to analog functions may be assigned to digital functions or used as GPIO. Most digital functions rely on the Crossbar for pin assignment; however, some digital functions bypass the Crossbar in a manner similar to the analog functions listed above. Port pins used by these digital functions and any Port pins selected for use as GPIO should have their corresponding bit in PnSKIP set to 1. Table 21.2 shows all available digital functions and the potential mapping of Port I/O to each digital function. Table 21.2. Port I/O Assignment for Digital Functions Digital Function Potentially Assignable Port Pins Any Port pin available for assignment by the UART0, SPI1, SPI0, SMBus, Crossbar. This includes P0.0–P2.6 pins which CP0 and CP1 Outputs, System Clock Output, PCA0, have their PnSKIP bit set to 0. Timer0 and Timer1 External Note: The Crossbar will always assign UART0 and SPI1 pins to fixed locations. Inputs. SFR(s) used for Assignment XBR0, XBR1, XBR2 Any pin used for GPIO P0.0–P2.6 P0SKIP, P1SKIP, P2SKIP External Memory Interface P1.0–P2.6 P1SKIP, P2SKIP EMI0CF 21.2.3. Assigning Port I/O Pins to External Digital Event Capture Functions External digital event capture functions can be used to trigger an interrupt or wake the device from a low power mode when a transition occurs on a digital I/O pin. The digital event capture functions do not require dedicated pins and will function on both GPIO pins (PnSKIP = 1) and pins in use by the Crossbar (PnSKIP = 0). External digital even capture functions cannot be used on pins configured for analog I/O. Table 21.3 shows all available external digital event capture functions. Table 21.3. Port I/O Assignment for External Digital Event Capture Functions Digital Function Potentially Assignable Port Pins SFR(s) used for Assignment External Interrupt 0 P0.0–P0.7 IT01CF External Interrupt 1 P0.0–P0.7 IT01CF P0.0–P1.7 P0MASK, P0MAT P1MASK, P1MAT Port Match Note: On C8051F931/21 devices Port Match is not available on P1.6 or P1.7. Rev. 1.4 220 C8051F93x-C8051F92x 21.3. Priority Crossbar Decoder The Priority Crossbar Decoder assigns a Port I/O pin to each software selected digital function using the fixed peripheral priority order shown in Figure 21.3. The registers XBR0, XBR1, and XBR2 defined in SFR Definition 21.1, SFR Definition 21.2, and SFR Definition 21.3 are used to select digital functions in the Crossbar. The Port pins available for assignment by the Crossbar include all Port pins (P0.0–P2.6) which have their corresponding bit in PnSKIP set to 0. From Figure 21.3, the highest priority peripheral is UART0. If UART0 is selected in the Crossbar (using the XBRn registers), then P0.4 and P0.5 will be assigned to UART0. The next highest priority peripheral is SPI1. If SPI1 is selected in the Crossbar, then P1.0–P1.2 will be assigned to SPI1. P1.3 will be assigned if SPI1 is configured for 4-wire mode. The user should ensure that the pins to be assigned by the Crossbar have their PnSKIP bits set to 0. For all remaining digital functions selected in the Crossbar, starting at the top of Figure 21.3 going down, the least-significant unskipped, unassigned Port pin(s) are assigned to that function. If a Port pin is already assigned (e.g., UART0 or SPI1 pins), or if its PnSKIP bit is set to 1, then the Crossbar will skip over the pin and find next available unskipped, unassigned Port pin. All Port pins used for analog functions, GPIO, or dedicated digital functions such as the EMIF should have their PnSKIP bit set to 1. Figure 21.3 shows the Crossbar Decoder priority with no Port pins skipped (P0SKIP, P1SKIP, P2SKIP = 0x00); Figure 21.4 shows the Crossbar Decoder priority with the External Oscillator pins (XTAL1 and XTAL2) skipped (P0SKIP = 0x0C). Important Notes: • • • • 221 The Crossbar must be enabled (XBARE = 1) before any Port pin is used as a digital output. Port output drivers are disabled while the Crossbar is disabled. When SMBus is selected in the Crossbar, the pins associated with SDA and SCL will automatically be forced into open-drain output mode regardless of the PnMDOUT setting. SPI0 can be operated in either 3-wire or 4-wire modes, depending on the state of the NSSMD1-NSSMD0 bits in register SPI0CN. The NSS signal is only routed to a Port pin when 4-wire mode is selected. When SPI0 is selected in the Crossbar, the SPI0 mode (3-wire or 4-wire) will affect the pinout of all digital functions lower in priority than SPI0. For given XBRn, PnSKIP, and SPInCN register settings, one can determine the I/O pin-out of the device using Figure 21.3 and Figure 21.4. Rev. 1.4 C8051F93x-C8051F92x AD4 AD5 AD6 AD7 A8 A9 A10 A11 ALE /RD /WR C2D 5 AD3 4 AD2 3 AD1 2 AD0 1 P2 IREF0 XTAL2 0 P1 CNVSTR XTAL1 PIN I/O AGND SF Signals VREF P0 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 TX0 RX0 SCK (SPI1) MISO (SPI1) MOSI (SPI1) (*4-Wire SPI Only) NSS* (SPI1) SCK (SPI0) MISO (SPI0) MOSI (SPI0) (*4-Wire SPI Only) NSS* (SPI0) SDA SCL CP0 CP0A CP1 CP1A /SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI T0 T1 0 0 0 0 0 0 P0SKIP[0:7] 0 0 0 0 0 0 0 0 P1SKIP[0:7] 0 0 0 0 0 0 0 0 0 X P2SKIP[0:7] Figure 21.3. Crossbar Priority Decoder with No Pins Skipped Rev. 1.4 222 C8051F93x-C8051F92x 1 2 3 4 5 6 7 A11 AD7 0 ALE /RD /WR C2D AD6 7 0 1 2 3 4 5 6 7 A9 A10 AD5 6 A8 AD4 5 AD3 4 AD2 3 AD1 2 AD0 1 P2 IREF0 XTAL2 0 P1 CNVSTR XTAL1 PIN I/O AGND SF Signals VREF P0 TX0 RX0 SCK (SPI1) MISO (SPI1) MOSI (SPI1) (*4-Wire SPI Only) NSS* (SPI1) SCK (SPI0) MISO (SPI0) MOSI (SPI0) (*4-Wire SPI Only) NSS* (SPI0) SDA SCL CP0 CP0A CP1 CP1A /SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI T0 T1 0 0 0 0 0 0 P0SKIP[0:7] 0 0 0 0 0 0 0 0 P1SKIP[0:7] 0 0 0 0 0 0 0 0 0 X P2SKIP[0:7] Figure 21.4. Crossbar Priority Decoder with Crystal Pins Skipped 223 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.1. XBR0: Port I/O Crossbar Register 0 Bit 7 6 5 4 3 2 1 0 Name CP1AE CP1E CP0AE CP0E SYSCKE SMB0E SPI0E URT0E Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xE1 Bit Name 7 CP1AE Function Comparator1 Asynchronous Output Enable. 0: Asynchronous CP1 output unavailable at Port pin. 1: Asynchronous CP1 output routed to Port pin. 6 CP1E Comparator1 Output Enable. 0: CP1 output unavailable at Port pin. 1: CP1 output routed to Port pin. 5 CP0AE Comparator0 Asynchronous Output Enable. 0: Asynchronous CP0 output unavailable at Port pin. 1: Asynchronous CP0 output routed to Port pin. 4 CP0E Comparator0 Output Enable. 0: CP1 output unavailable at Port pin. 1: CP1 output routed to Port pin. 3 SYSCKE SYSCLK Output Enable. 0: SYSCLK output unavailable at Port pin. 1: SYSCLK output routed to Port pin. 2 SMB0E SMBus I/O Enable. 0: SMBus I/O unavailable at Port pin. 1: SDA and SCL routed to Port pins. 1 SPI0E SPI0 I/O Enable 0: SPI0 I/O unavailable at Port pin. 1: SCK, MISO, and MOSI (for SPI0) routed to Port pins. NSS (for SPI0) routed to Port pin only if SPI0 is configured to 4-wire mode. 0 URT0E UART0 Output Enable. 0: UART I/O unavailable at Port pin. 1: TX0 and RX0 routed to Port pins P0.4 and P0.5. Note: SPI0 can be assigned either 3 or 4 Port I/O pins. Rev. 1.4 224 C8051F93x-C8051F92x SFR Definition 21.2. XBR1: Port I/O Crossbar Register 1 Bit 7 Name 6 5 4 3 SPI1E T1E T0E ECIE 2 1 0 PCA0ME[2:0] Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xE2 Bit Name 7 Unused Function Unused. Read = 0b; Write = Don’t Care. 6 SPI1E SPI1 I/O Enable. 0: SPI0 I/O unavailable at Port pin. 1: SCK (for SPI1) routed to P1.0. MISO (for SPI1) routed to P1.1. MOSI (for SPI1) routed to P1.2. NSS (for SPI1) routed to P1.3 only if SPI1 is configured to 4-wire mode. 5 T1E Timer1 Input Enable. 0: T1 input unavailable at Port pin. 1: T1 input routed to Port pin. 4 T0E Timer0 Input Enable. 0: T0 input unavailable at Port pin. 1: T0 input routed to Port pin. 3 ECIE PCA0 External Counter Input (ECI) Enable. 0: PCA0 external counter input unavailable at Port pin. 1: PCA0 external counter input routed to Port pin. 2:0 PCA0ME PCA0 Module I/O Enable. 000: All PCA0 I/O unavailable at Port pin. 001: CEX0 routed to Port pin. 010: CEX0, CEX1 routed to Port pins. 011: CEX0, CEX1, CEX2 routed to Port pins. 100: CEX0, CEX1, CEX2 CEX3 routed to Port pins. 101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins. 110: CEX0, CEX1, CEX2, CEX3, CEX4, CEX5 routed to Port pins. 111: Reserved. Note: SPI1 can be assigned either 3 or 4 Port I/O pins. 225 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.3. XBR2: Port I/O Crossbar Register 2 Bit 7 6 5 4 3 2 1 0 Name WEAKPUD XBARE Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xE3 Bit Name 7 6 WEAKPUD XBARE Function Port I/O Weak Pullup Disable 0: Weak Pullups enabled (except for Port I/O pins configured for analog mode). Crossbar Enable 0: Crossbar disabled. 1: Crossbar enabled. 5:0 Unused Unused. Read = 000000b; Write = Don’t Care. Note: The Crossbar must be enabled (XBARE = 1) to use any Port pin as a digital output. Rev. 1.4 226 C8051F93x-C8051F92x 21.4. Port Match Port match functionality allows system events to be triggered by a logic value change on P0 or P1. A software controlled value stored in the PnMAT registers specifies the expected or normal logic values of P0 and P1. A Port mismatch event occurs if the logic levels of the Port’s input pins no longer match the software controlled value. This allows Software to be notified if a certain change or pattern occurs on P0 or P1 input pins regardless of the XBRn settings. Note: On C8051F931/21 devices, Port Match is not available on P1.6 or P1.7. The PnMASK registers can be used to individually select which P0 and P1 pins should be compared against the PnMAT registers. A Port mismatch event is generated if (P0 & P0MASK) does not equal (PnMAT & P0MASK) or if (P1 & P1MASK) does not equal (PnMAT & P1MASK). A Port mismatch event may be used to generate an interrupt or wake the device from a low power mode. See Section “12. Interrupt Handler” on page 136 and Section “14. Power Management” on page 159 for more details on interrupt and wake-up sources. SFR Definition 21.4. P0MASK: Port0 Mask Register Bit 7 6 5 4 3 Name P0MASK[7:0] Type R/W Reset 0 0 0 0 0 SFR Page= 0x0; SFR Address = 0xC7 Bit Name 7:0 2 1 0 0 0 0 Function P0MASK[7:0] Port0 Mask Value. Selects the P0 pins to be compared with the corresponding bits in P0MAT. 0: P0.n pin pad logic value is ignored and cannot cause a Port Mismatch event. 1: P0.n pin pad logic value is compared to P0MAT.n. SFR Definition 21.5. P0MAT: Port0 Match Register Bit 7 6 5 4 3 Name P0MAT[7:0] Type R/W Reset 1 1 1 1 SFR Page= 0x0; SFR Address = 0xD7 Bit Name 7 :0 1 2 1 0 1 1 1 Function P0MAT[7:0] Port 0 Match Value. Match comparison value used on Port 0 for bits in P0MASK which are set to 1. 0: P0.n pin logic value is compared with logic LOW. 1: P0.n pin logic value is compared with logic HIGH. 227 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.6. P1MASK: Port1 Mask Register Bit 7 6 5 4 3 Name P1MASK[7:0] Type R/W Reset 0 0 0 0 0 SFR Page= 0x0; SFR Address = 0xBF Bit Name 7:0 2 1 0 0 0 0 Function P1MASK[7:0] Port 1 Mask Value. Selects P1 pins to be compared to the corresponding bits in P1MAT. 0: P1.n pin logic value is ignored and cannot cause a Port Mismatch event. 1: P1.n pin logic value is compared to P1MAT.n. Note: On C8051F931/21 devices, port match is not available on P1.6 or P1.7. The corresponding P1MASK bits must be set to 0b. SFR Definition 21.7. P1MAT: Port1 Match Register Bit 7 6 5 4 3 Name P1MAT[7:0] Type R/W Reset 1 1 1 SFR Page = 0x0; SFR Address = 0xCF Bit Name 7:0 1 1 2 1 0 1 1 1 Function P1MAT[7:0] Port 1 Match Value. Match comparison value used on Port 1 for bits in P1MASK which are set to 1. 0: P1.n pin logic value is compared with logic LOW. 1: P1.n pin logic value is compared with logic HIGH. Note: On C8051F931/21 devices, port match is not available on P1.6 or P1.7. Rev. 1.4 228 C8051F93x-C8051F92x 21.5. Special Function Registers for Accessing and Configuring Port I/O All Port I/O are accessed through corresponding special function registers (SFRs) that are both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is latched to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write instructions that target a Port Latch register as the destination. The read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SETB, when the destination is an individual bit in a Port SFR. For these instructions, the value of the latch register (not the pin) is read, modified, and written back to the SFR. Each Port has a corresponding PnSKIP register which allows its individual Port pins to be assigned to digital functions or skipped by the Crossbar. All Port pins used for analog functions, GPIO, or dedicated digital functions such as the EMIF should have their PnSKIP bit set to 1. The Port input mode of the I/O pins is defined using the Port Input Mode registers (PnMDIN). Each Port cell can be configured for analog or digital I/O. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is P2.7, which can only be used for digital I/O. The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the PnMDOUT settings. The drive strength of the output drivers are controlled by the Port Drive Strength (PnDRV) registers. The default is low drive strength. See Section “4. Electrical Characteristics” on page 45 for the difference in output drive strength between the two modes. 229 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.8. P0: Port0 Bit 7 6 5 4 Name P0[7:0] Type R/W Reset 1 1 1 1 3 2 1 0 1 1 1 1 SFR Page = All Pages; SFR Address = 0x80; Bit-Addressable Bit Name Description Write 7:0 P0[7:0] Read 0: Set output latch to logic LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic logic state in Port cells con- HIGH. figured for digital I/O. Port 0 Data. 0: P0.n Port pin is logic LOW. 1: P0.n Port pin is logic HIGH. SFR Definition 21.9. P0SKIP: Port0 Skip Bit 7 6 5 4 3 Name P0SKIP[7:0] Type R/W Reset 0 0 0 0 0 SFR Page= 0x0; SFR Address = 0xD4 Bit Name 7:0 2 1 0 0 0 0 Function P0SKIP[7:0] Port 0 Crossbar Skip Enable Bits. These bits select Port 0 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P0.n pin is not skipped by the Crossbar. 1: Corresponding P0.n pin is skipped by the Crossbar. Rev. 1.4 230 C8051F93x-C8051F92x SFR Definition 21.10. P0MDIN: Port0 Input Mode Bit 7 6 5 4 3 Name P0MDIN[7:0] Type R/W Reset 1 1 1 1 1 SFR Page= 0x0; SFR Address = 0xF1 Bit Name 7:0 P0MDIN[7:0] 2 1 0 1 1 1 Function Analog Configuration Bits for P0.7–P0.0 (respectively). Port pins configured for analog mode have their weak pullup, and digital receiver disabled. The digital driver is not explicitly disabled. 0: Corresponding P0.n pin is configured for analog mode. 1: Corresponding P0.n pin is not configured for analog mode. SFR Definition 21.11. P0MDOUT: Port0 Output Mode Bit 7 6 5 4 3 Name P0MDOUT[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0x0; SFR Address = 0xA4 Bit Name 7:0 0 2 1 0 0 0 0 Function P0MDOUT[7:0] Output Configuration Bits for P0.7–P0.0 (respectively). These bits control the digital driver even when the corresponding bit in register P0MDIN is logic 0. 0: Corresponding P0.n Output is open-drain. 1: Corresponding P0.n Output is push-pull. 231 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.12. P0DRV: Port0 Drive Strength Bit 7 6 5 4 3 Name P0DRV[7:0] Type R/W Reset 0 0 0 SFR Page = 0xF; SFR Address = 0xA4 Bit Name 7:0 0 0 2 1 0 0 0 0 Function P0DRV[7:0] Drive Strength Configuration Bits for P0.7–P0.0 (respectively). Configures digital I/O Port cells to high or low output drive strength. 0: Corresponding P0.n Output has low output drive strength. 1: Corresponding P0.n Output has high output drive strength. Rev. 1.4 232 C8051F93x-C8051F92x SFR Definition 21.13. P1: Port1 Bit 7 6 5 4 Name P1[7:0] Type R/W Reset 1 1 1 1 3 2 1 0 1 1 1 1 SFR Page = All Pages; SFR Address = 0x90; Bit-Addressable Bit Name Description Write 7:0 P1[7:0] Read 0: Set output latch to logic LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic logic state in Port cells con- HIGH. figured for digital I/O. Port 1 Data. 0: P1.n Port pin is logic LOW. 1: P1.n Port pin is logic HIGH. Note: Pin P1.7 is only available in 32-pin devices. SFR Definition 21.14. P1SKIP: Port1 Skip Bit 7 6 5 4 3 Name P1SKIP[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0x0; SFR Address = 0xD5 Bit Name 7:0 0 2 1 0 0 0 0 Function P1SKIP[7:0] Port 1 Crossbar Skip Enable Bits. These bits select Port 1 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P1.n pin is not skipped by the Crossbar. 1: Corresponding P1.n pin is skipped by the Crossbar. Note: Pin P1.7 is only available in 32-pin devices. 233 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 21.15. P1MDIN: Port1 Input Mode Bit 7 6 5 4 3 Name P1MDIN[7:0] Type R/W Reset 1 1 1 1 1 SFR Page = 0x0; SFR Address = 0xF2 Bit Name 7:0 P1MDIN[7:0] 2 1 0 1 1 1 Function Analog Configuration Bits for P1.7–P1.0 (respectively). Port pins configured for analog mode have their weak pullup and digital receiver disabled. The digital driver is not explicitly disabled. 0: Corresponding P1.n pin is configured for analog mode. 1: Corresponding P1.n pin is not configured for analog mode. Note: Pin P1.7 is only available in 32-pin devices. SFR Definition 21.16. P1MDOUT: Port1 Output Mode Bit 7 6 5 4 3 Name P1MDOUT[7:0] Type R/W Reset 0 0 0 SFR Page = 0x0; SFR Address = 0xA5 Bit Name 7:0 0 0 2 1 0 0 0 0 Function P1MDOUT[7:0] Output Configuration Bits for P1.7–P1.0 (respectively). These bits control the digital driver even when the corresponding bit in register P1MDIN is logic 0. 0: Corresponding P1.n Output is open-drain. 1: Corresponding P1.n Output is push-pull. Note: Pin P1.7 is only available in 32-pin devices. Rev. 1.4 234 C8051F93x-C8051F92x SFR Definition 21.17. P1DRV: Port1 Drive Strength Bit 7 6 5 4 3 Name P1DRV[7:0] Type R/W Reset 0 0 0 0 0 SFR Page = 0xF; SFR Address = 0xA5 Bit Name 7:0 2 1 0 0 0 0 Function P1DRV[7:0] Drive Strength Configuration Bits for P1.7–P1.0 (respectively). Configures digital I/O Port cells to high or low output drive strength. 0: Corresponding P1.n Output has low output drive strength. 1: Corresponding P1.n Output has high output drive strength. Note: Pin P1.7 is only available in 32-pin devices. SFR Definition 21.18. P2: Port2 Bit 7 6 5 4 Name P2[7:0] Type R/W Reset 1 1 1 1 3 2 1 0 1 1 1 1 SFR Page = All Pages; SFR Address = 0xA0; Bit-Addressable Bit Name 7:0 P2[7:0] Description Write 0: Set output latch to logic LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic logic state in Port cells con- HIGH. figured for digital I/O. Port 2 Data. Note: Pins P2.0-P2.6 are only available in 32-pin devices. 235 Rev. 1.4 Read 0: P2.n Port pin is logic LOW. 1: P2.n Port pin is logic HIGH. C8051F93x-C8051F92x SFR Definition 21.19. P2SKIP: Port2 Skip Bit 7 6 5 4 3 Name P2SKIP[7:0] Type R/W Reset 0 0 0 0 0 2 1 0 0 0 0 SFR Page = 0x0; SFR Address = 0xD6 Bit Name 7:0 P2SKIP[7:0] Description Read Write Port 1 Crossbar Skip Enable Bits. These bits select Port 2 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P2.n pin is not skipped by the Crossbar. 1: Corresponding P2.n pin is skipped by the Crossbar. Note: Pins P2.0-P2.6 are only available in 32-pin devices. SFR Definition 21.20. P2MDIN: Port2 Input Mode Bit 7 Name Reserved 6 5 4 3 0 1 1 1 R/W 1 1 1 1 1 SFR Page = 0x0; SFR Address = 0xF3 Bit Name 7 6:0 1 P2MDIN[6:0] Type Reset 2 Function Reserved. Read = 1b; Must Write 1b. P2MDIN[3:0] Analog Configuration Bits for P2.6–P2.0 (respectively). Port pins configured for analog mode have their weak pullup and digital receiver disabled. The digital driver is not explicitly disabled. 0: Corresponding P2.n pin is configured for analog mode. 1: Corresponding P2.n pin is not configured for analog mode. Note: Pins P2.0-P2.6 are only available in 32-pin devices. Rev. 1.4 236 C8051F93x-C8051F92x SFR Definition 21.21. P2MDOUT: Port2 Output Mode Bit 7 6 5 4 3 Name P2MDOUT[7:0] Type R/W Reset 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xA6 Bit Name 7:0 2 1 0 0 0 0 Function P2MDOUT[7:0] Output Configuration Bits for P2.7–P2.0 (respectively). These bits control the digital driver even when the corresponding bit in register P2MDIN is logic 0. 0: Corresponding P2.n Output is open-drain. 1: Corresponding P2.n Output is push-pull. Note: Pins P2.0-P2.6 are only available in 32-pin devices. SFR Definition 21.22. P2DRV: Port2 Drive Strength Bit 7 6 5 4 3 Name P2DRV[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0x0F; SFR Address = 0xA6 Bit Name 7:0 P2DRV[7:0] 0 2 1 0 0 0 0 Function Drive Strength Configuration Bits for P2.7–P2.0 (respectively). Configures digital I/O Port cells to high or low output drive strength. 0: Corresponding P2.n Output has low output drive strength. 1: Corresponding P2.n Output has high output drive strength. Note: Pins P2.0-P2.6 are only available in 32-pin devices. 237 Rev. 1.4 C8051F93x-C8051F92x 22. SMBus The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to the interface by the system controller are byte oriented with the SMBus interface autonomously controlling the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. The SMBus peripheral can be fully driven by software (i.e., software accepts/rejects slave addresses, and generates ACKs), or hardware slave address recognition and automatic ACK generation can be enabled to minimize software overhead. A block diagram of the SMBus peripheral and the associated SFRs is shown in Figure 22.1. SMB0CN M T S S A A A S A X T T CR C I SMAOK B K T O R L E D QO R E S T SMB0CF E I B E S S S S N N U XMMMM S H S T B B B B M Y H T F CC B OO T S S L E E 1 0 D SMBUS CONTROL LOGIC Arbitration SCL Synchronization SCL Generation (Master Mode) SDA Control Hardware Slave Address Recognition Hardware ACK Generation Data Path IRQ Generation Control Interrupt Request 00 T0 Overflow 01 T1 Overflow 10 TMR2H Overflow 11 TMR2L Overflow SCL Control S L V 5 S L V 4 S L V 3 S L V 2 S L V 1 SMB0ADR SG L C V 0 S S S S S S S L L L L L L L V V V V V V V MMMMMMM 6 5 4 3 2 1 0 SMB0ADM C R O S S B A R N SDA Control SMB0DAT 7 6 5 4 3 2 1 0 S L V 6 SCL FILTER Port I/O SDA FILTER E H A C K N Figure 22.1. SMBus Block Diagram Rev. 1.4 238 C8051F93x-C8051F92x 22.1. Supporting Documents It is assumed the reader is familiar with or has access to the following supporting documents: 1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor. 2. The I2C-Bus Specification—Version 2.0, Philips Semiconductor. 3. System Management Bus Specification—Version 1.1, SBS Implementers Forum. 22.2. SMBus Configuration Figure 22.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bidirectional 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 opendrain or open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus not exceed 300 ns and 1000 ns, respectively. VDD = 5 V VDD = 3 V VDD = 5 V VDD = 3 V Master Device Slave Device 1 Slave Device 2 SDA SCL Figure 22.2. Typical SMBus Configuration 239 Rev. 1.4 C8051F93x-C8051F92x 22.3. SMBus Operation Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ). The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitration. Note that it is not necessary to specify one device as the Master in a system; any device who transmits a START and a slave address becomes the master for the duration of that transfer. A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Bytes that are received (by a master or slave) are acknowledged (ACK) with a low SDA during a high SCL (see Figure 22.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation. All transactions are initiated by a master, with one or more addressed slave devices as the target. The master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master generates a STOP condition to terminate the transaction and free the bus. Figure 22.3 illustrates a typical SMBus transaction. SCL SDA SLA6 START SLA5-0 Slave Address + R/W R/W D7 ACK D6-0 Data Byte NACK STOP Figure 22.3. SMBus Transaction 22.3.1. Transmitter Vs. Receiver On the SMBus communications interface, a device is the “transmitter” when it is sending an address or data byte to another device on the bus. A device is a “receiver” when an address or data byte is being sent to it from another device on the bus. The transmitter controls the SDA line during the address or data byte. After each byte of address or data information is sent by the transmitter, the receiver sends an ACK or NACK bit during the ACK phase of the transfer, during which time the receiver controls the SDA line. Rev. 1.4 240 C8051F93x-C8051F92x 22.3.2. Arbitration A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section “22.3.5. SCL High (SMBus Free) Timeout” on page 241). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device always wins, and no data is lost. 22.3.3. Clock Low Extension SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line LOW to extend the clock low period, effectively decreasing the serial clock frequency. 22.3.4. SCL Low Timeout If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition. When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable and re-enable) the SMBus in the event of an SCL low timeout. 22.3.5. SCL High (SMBus Free) Timeout The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods (as defined by the timer configured for the SMBus clock source). If the SMBus is waiting to generate a Master START, the START will be generated following this timeout. A clock source is required for free timeout detection, even in a slave-only implementation. 241 Rev. 1.4 C8051F93x-C8051F92x 22.4. Using the SMBus The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides the following application-independent features: • • • • • • • • Byte-wise serial data transfers Clock signal generation on SCL (Master Mode only) and SDA data synchronization Timeout/bus error recognition, as defined by the SMB0CF configuration register START/STOP timing, detection, and generation Bus arbitration Interrupt generation Status information Optional hardware recognition of slave address and automatic acknowledgement of address/data SMBus interrupts are generated for each data byte or slave address that is transferred. When hardware acknowledgement is disabled, the point at which the interrupt is generated depends on whether the hardware is acting as a data transmitter or receiver. When a transmitter (i.e., sending address/data, receiving an ACK), this interrupt is generated after the ACK cycle so that software may read the received ACK value; when receiving data (i.e., receiving address/data, sending an ACK), this interrupt is generated before the ACK cycle so that software may define the outgoing ACK value. If hardware acknowledgement is enabled, these interrupts are always generated after the ACK cycle. See Section 22.5 for more details on transmission sequences. Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section 22.4.2; Table 22.5 provides a quick SMB0CN decoding reference. Rev. 1.4 242 C8051F93x-C8051F92x 22.4.1. SMBus Configuration Register The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes, select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however, the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of the current transfer). Table 22.1. SMBus Clock Source Selection SMBCS1 0 0 1 1 SMBCS0 0 1 0 1 SMBus Clock Source Timer 0 Overflow Timer 1 Overflow Timer 2 High Byte Overflow Timer 2 Low Byte Overflow The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or when the Free Timeout detection is enabled. When operating as a master, overflows from the selected source determine the absolute minimum SCL low and high times as defined in Equation 22.1. The selected clock source may be shared by other peripherals so long as the timer is left running at all times. For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer configuration is covered in Section “25. Timers” on page 283. 1 T HighMin = T LowMin = ---------------------------------------------f ClockSourceOverflow Equation 22.1. Minimum SCL High and Low Times The selected clock source should be configured to establish the minimum SCL High and Low times as per Equation 22.1. When the interface is operating as a master (and SCL is not driven or extended by any other devices on the bus), the typical SMBus bit rate is approximated by Equation 22.2. f ClockSourceOverflow BitRate = ---------------------------------------------3 Equation 22.2. Typical SMBus Bit Rate Figure 22.4 shows the typical SCL generation described by Equation 22.2. Notice that THIGH is typically twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be extended low by slower slave devices, or driven low by contending master devices). The bit rate when operating as a master will never exceed the limits defined by equation Equation 22.1. Timer Source Overflows SCL TLow THigh SCL High Timeout Figure 22.4. Typical SMBus SCL Generation 243 Rev. 1.4 C8051F93x-C8051F92x Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high. The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 22.2 shows the minimum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically necessary when SYSCLK is above 10 MHz. Table 22.2. Minimum SDA Setup and Hold Times EXTHOLD Minimum SDA Setup Time Minimum SDA Hold Time Tlow – 4 system clocks 0 3 system clocks or 1 system clock + s/w delay* 1 11 system clocks 12 system clocks *Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. When using software acknowledgement, the s/w delay occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w delay is zero. With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low timeouts (see Section “22.3.4. SCL Low Timeout” on page 241). The SMBus interface will force Timer 3 to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus. SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see Figure 22.4). Rev. 1.4 244 C8051F93x-C8051F92x SFR Definition 22.1. SMB0CF: SMBus Clock/Configuration Bit 7 6 5 4 Name ENSMB INH BUSY Type R/W R/W R R/W Reset 0 0 0 0 EXTHOLD SMBTOE SFR Page = 0x0; SFR Address = 0xC1 Bit Name 7 ENSMB 3 2 1 0 SMBFTE SMBCS[1:0] R/W R/W R/W 0 0 0 0 Function SMBus Enable. This bit enables the SMBus interface when set to 1. When enabled, the interface constantly monitors the SDA and SCL pins. 6 INH SMBus Slave Inhibit. When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are not affected. 5 BUSY SMBus Busy Indicator. This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0 when a STOP or free-timeout is sensed. 4 EXTHOLD SMBus Setup and Hold Time Extension Enable. This bit controls the SDA setup and hold times according to Table 22.2. 0: SDA Extended Setup and Hold Times disabled. 1: SDA Extended Setup and Hold Times enabled. 3 SMBTOE SMBus SCL Timeout Detection Enable. This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low. If Timer 3 is configured to Split Mode, only the High Byte of the timer is held in reload while SCL is high. Timer 3 should be programmed to generate interrupts at 25 ms, and the Timer 3 interrupt service routine should reset SMBus communication. 2 SMBFTE SMBus Free Timeout Detection Enable. When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. 1 :0 SMBCS[1:0] SMBus Clock Source Selection. These two bits select the SMBus clock source, which is used to generate the SMBus bit rate. The selected device should be configured according to Equation 22.1. 00: Timer 0 Overflow 01: Timer 1 Overflow 10:Timer 2 High Byte Overflow 11: Timer 2 Low Byte Overflow 245 Rev. 1.4 C8051F93x-C8051F92x 22.4.2. SMB0CN Control Register SMB0CN is used to control the interface and to provide status information (see SFR Definition 22.2). The higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to jump to service routines. MASTER indicates whether a device is the master or slave during the current transfer. TXMODE indicates whether the device is transmitting or receiving data for the current byte. STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a 1 to STA will cause the SMBus interface to enter Master Mode and generate a START when the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a 1 to STO while in Master Mode will cause the interface to generate a STOP and end the current transfer after the next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be generated. The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared. The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or when an arbitration is lost; see Table 22.3 for more details. Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and the bus is stalled until software clears SI. 22.4.2.1.Software ACK Generation When the EHACK bit in register SMB0ADM is cleared to 0, the firmware on the device must detect incoming slave addresses and ACK or NACK the slave address and incoming data bytes. As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value received during the last ACK cycle. ACKRQ is set each time a byte is received, indicating that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be ignored until the next START is detected. 22.4.2.2.Hardware ACK Generation When the EHACK bit in register SMB0ADM is set to 1, automatic slave address recognition and ACK generation is enabled. More detail about automatic slave address recognition can be found in Section 22.4.3. As a receiver, the value currently specified by the ACK bit will be automatically sent on the bus during the ACK cycle of an incoming data byte. As a transmitter, reading the ACK bit indicates the value received on the last ACK cycle. The ACKRQ bit is not used when hardware ACK generation is enabled. If a received slave address is NACKed by hardware, further slave events will be ignored until the next START is detected, and no interrupt will be generated. Table 22.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 22.5 for SMBus status decoding using the SMB0CN register. Refer to the C8051F930 errata when using hardware ACK generation on C8051F930/31/20/21 devices. Rev. 1.4 246 C8051F93x-C8051F92x SFR Definition 22.2. SMB0CN: SMBus Control Bit 7 6 5 4 3 2 1 0 Name MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI Type R R R/W R/W R R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xC0; Bit-Addressable Bit Name Description Read Write 7 MASTER SMBus Master/Slave Indicator. This read-only bit indicates when the SMBus is operating as a master. 0: SMBus operating in slave mode. 1: SMBus operating in master mode. N/A 6 TXMODE SMBus Transmit Mode Indicator. This read-only bit indicates when the SMBus is operating as a transmitter. 0: SMBus in Receiver Mode. 1: SMBus in Transmitter Mode. N/A 5 STA SMBus Start Flag. 0: No Start or repeated Start detected. 1: Start or repeated Start detected. 0: No Start generated. 1: When Configured as a Master, initiates a START or repeated START. 4 STO SMBus Stop Flag. 0: No Stop condition detected. 1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode). 0: No STOP condition is transmitted. 1: When configured as a Master, causes a STOP condition to be transmitted after the next ACK cycle. Cleared by Hardware. 3 ACKRQ SMBus Acknowledge Request. 0: No Ack requested 1: ACK requested N/A 0: No arbitration error. 1: Arbitration Lost N/A 2 ARBLOST SMBus Arbitration Lost Indicator. 1 ACK SMBus Acknowledge. 0: NACK received. 1: ACK received. 0: Send NACK 1: Send ACK 0 SI SMBus Interrupt Flag. 0: No interrupt pending 0: Clear interrupt, and initiate next state machine event. 1: Force interrupt. This bit is set by hardware 1: Interrupt Pending under the conditions listed in Table 15.3. SI must be cleared by software. While SI is set, SCL is held low and the SMBus is stalled. 247 Rev. 1.4 C8051F93x-C8051F92x Table 22.3. Sources for Hardware Changes to SMB0CN Bit Set by Hardware When: MASTER • A START is generated. TXMODE • START is generated. • SMB0DAT is written before the start of an SMBus frame. STA STO ACKRQ ARBLOST ACK SI • A START followed by an address byte is received. • A STOP is detected while addressed as a slave. • Arbitration is lost due to a detected STOP. • A byte has been received and an ACK response value is needed (only when hardware ACK is not enabled). • A repeated START is detected as a MASTER when STA is low (unwanted repeated START). • SCL is sensed low while attempting to generate a STOP or repeated START condition. • SDA is sensed low while transmitting a 1 (excluding ACK bits). • The incoming ACK value is low (ACKNOWLEDGE). • A START has been generated. • Lost arbitration. • A byte has been transmitted and an ACK/NACK received. • A byte has been received. • A START or repeated START followed by a slave address + R/W has been received. • A STOP has been received. Rev. 1.4 Cleared by Hardware When: • A STOP is generated. • Arbitration is lost. • A START is detected. • Arbitration is lost. • SMB0DAT is not written before the start of an SMBus frame. • Must be cleared by software. • A pending STOP is generated. • After each ACK cycle. • Each time SI is cleared. • The incoming ACK value is high (NOT ACKNOWLEDGE). • Must be cleared by software. 248 C8051F93x-C8051F92x 22.4.3. Hardware Slave Address Recognition The SMBus hardware has the capability to automatically recognize incoming slave addresses and send an ACK without software intervention. Automatic slave address recognition is enabled by setting the EHACK bit in register SMB0ADM to 1. This will enable both automatic slave address recognition and automatic hardware ACK generation for received bytes (as a master or slave). More detail on automatic hardware ACK generation can be found in Section 22.4.2.2. The registers used to define which address(es) are recognized by the hardware are the SMBus Slave Address register (SFR Definition 22.3) and the SMBus Slave Address Mask register (SFR Definition 22.4). A single address or range of addresses (including the General Call Address 0x00) can be specified using these two registers. The most-significant seven bits of the two registers are used to define which addresses will be ACKed. A 1 in bit positions of the slave address mask SLVM[6:0] enable a comparison between the received slave address and the hardware’s slave address SLV[6:0] for those bits. A 0 in a bit of the slave address mask means that bit will be treated as a “don’t care” for comparison purposes. In this case, either a 1 or a 0 value are acceptable on the incoming slave address. Additionally, if the GC bit in register SMB0ADR is set to 1, hardware will recognize the General Call Address (0x00). Table 22.4 shows some example parameter settings and the slave addresses that will be recognized by hardware under those conditions. Refer to the C8051F930 errata when using hardware ACK generation on C8051F930/31/20/21 devices. Table 22.4. Hardware Address Recognition Examples (EHACK = 1) Hardware Slave Address SLV[6:0] Slave Address Mask SLVM[6:0] GC bit Slave Addresses Recognized by Hardware 0x34 0x7F 0 0x34 0x34 0x7F 1 0x34, 0x00 (General Call) 0x34 0x7E 0 0x34, 0x35 0x34 0x7E 1 0x34, 0x35, 0x00 (General Call) 0x70 0x73 0 0x70, 0x74, 0x78, 0x7C 249 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 22.3. SMB0ADR: SMBus Slave Address Bit 7 6 5 4 3 2 1 0 Name SLV[6:0] GC Type R/W R/W Reset 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0xF4 Bit Name 7 :1 SLV[6:0] 0 0 0 Function SMBus Hardware Slave Address. Defines the SMBus Slave Address(es) for automatic hardware acknowledgement. Only address bits which have a 1 in the corresponding bit position in SLVM[6:0] are checked against the incoming address. This allows multiple addresses to be recognized. 0 GC General Call Address Enable. When hardware address recognition is enabled (EHACK = 1), this bit will determine whether the General Call Address (0x00) is also recognized by hardware. 0: General Call Address is ignored. 1: General Call Address is recognized. SFR Definition 22.4. SMB0ADM: SMBus Slave Address Mask Bit 7 6 5 4 3 2 1 0 Name SLVM[6:0] EHACK Type R/W R/W Reset 1 1 1 1 1 SFR Page = 0x0; SFR Address = 0xF5 Bit Name 7 :1 SLVM[6:0] 1 1 0 Function SMBus Slave Address Mask. Defines which bits of register SMB0ADR are compared with an incoming address byte, and which bits are ignored. Any bit set to 1 in SLVM[6:0] enables comparisons with the corresponding bit in SLV[6:0]. Bits set to 0 are ignored (can be either 0 or 1 in the incoming address). 0 EHACK Hardware Acknowledge Enable. Enables hardware acknowledgement of slave address and received data bytes. 0: Firmware must manually acknowledge all incoming address and data bytes. 1: Automatic Slave Address Recognition and Hardware Acknowledge is Enabled. Rev. 1.4 250 C8051F93x-C8051F92x 22.4.4. Data Register The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software may safely read or write to the data register when the SI flag is set. Software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0, as the interface may be in the process of shifting a byte of data into or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in SMB0DAT. SFR Definition 22.5. SMB0DAT: SMBus Data Bit 7 6 5 4 3 Name SMB0DAT[7:0] Type R/W Reset 0 0 0 0 SFR Page = 0x0; SFR Address = 0xC2 Bit Name 0 2 1 0 0 0 0 Function 7:0 SMB0DAT[7:0] SMBus Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long as the SI flag is set. When the SI flag is not set, the system may be in the process of shifting data in/out and the CPU should not attempt to access this register. 251 Rev. 1.4 C8051F93x-C8051F92x 22.5. SMBus Transfer Modes The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end of all SMBus byte frames. Note that the position of the ACK interrupt when operating as a receiver depends on whether hardware ACK generation is enabled. As a receiver, the interrupt for an ACK occurs before the ACK with hardware ACK generation disabled, and after the ACK when hardware ACK generation is enabled. As a transmitter, interrupts occur after the ACK, regardless of whether hardware ACK generation is enabled or not. 22.5.1. Write Sequence (Master) During a write sequence, an SMBus master writes data to a slave device. The master in this transfer will be a transmitter during the address byte, and a transmitter during all data bytes. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt. Figure 22.5 shows a typical master write sequence. Two transmit data bytes are shown, though any number of bytes may be transmitted. All “data byte transferred” interrupts occur after the ACK cycle in this mode, regardless of whether hardware ACK generation is enabled. Interrupts with Hardware ACK Enabled (EHACK = 1) S SLA W A Data Byte A Data Byte A P Interrupts with Hardware ACK Disabled (EHACK = 0) S = START P = STOP A = ACK W = WRITE SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 22.5. Typical Master Write Sequence Rev. 1.4 252 C8051F93x-C8051F92x 22.5.2. Read Sequence (Master) During a read sequence, an SMBus master reads data from a slave device. The master in this transfer will be a transmitter during the address byte, and a receiver during all data bytes. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial data. If hardware ACK generation is disabled, the ACKRQ is set to 1 and an interrupt is generated after each received byte. Software must write the ACK bit at that time to ACK or NACK the received byte. With hardware ACK generation enabled, the SMBus hardware will automatically generate the ACK/NACK, and then post the interrupt. It is important to note that the appropriate ACK or NACK value should be set up by the software prior to receiving the byte when hardware ACK generation is enabled. Writing a 1 to the ACK bit generates an ACK; writing a 0 generates a NACK. Software should write a 0 to the ACK bit for the last data transfer, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and a STOP is generated. The interface will switch to Master Transmitter Mode if SMB0DAT is written while an active Master Receiver. Figure 22.6 shows a typical master read sequence. Two received data bytes are shown, though any number of bytes may be received. The “data byte transferred” interrupts occur at different places in the sequence, depending on whether hardware ACK generation is enabled. The interrupt occurs before the ACK with hardware ACK generation disabled, and after the ACK when hardware ACK generation is enabled. Interrupts with Hardware ACK Enabled (EHACK = 1) S SLA R A Data Byte A Data Byte N Interrupts with Hardware ACK Disabled (EHACK = 0) S = START P = STOP A = ACK N = NACK R = READ SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 22.6. Typical Master Read Sequence 253 Rev. 1.4 P C8051F93x-C8051F92x 22.5.3. Write Sequence (Slave) During a write sequence, an SMBus master writes data to a slave device. The slave in this transfer will be a receiver during the address byte, and a receiver during all data bytes. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit (WRITE in this case) is received. If hardware ACK generation is disabled, upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The software must respond to the received slave address with an ACK, or ignore the received slave address with a NACK. If hardware ACK generation is enabled, the hardware will apply the ACK for a slave address which matches the criteria set up by SMB0ADR and SMB0ADM. The interrupt will occur after the ACK cycle. If the received slave address is ignored (by software or hardware), slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are received. If hardware ACK generation is disabled, the ACKRQ is set to 1 and an interrupt is generated after each received byte. Software must write the ACK bit at that time to ACK or NACK the received byte. With hardware ACK generation enabled, the SMBus hardware will automatically generate the ACK/NACK, and then post the interrupt. The appropriate ACK or NACK value should be set up by the software prior to receiving the byte when hardware ACK generation is enabled. The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 22.7 shows a typical slave write sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur at different places in the sequence, depending on whether hardware ACK generation is enabled. The interrupt occurs before the ACK with hardware ACK generation disabled, and after the ACK when hardware ACK generation is enabled. Interrupts with Hardware ACK Enabled (EHACK = 1) S SLA W A Data Byte A Data Byte A P Interrupts with Hardware ACK Disabled (EHACK = 0) S = START P = STOP A = ACK W = WRITE SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 22.7. Typical Slave Write Sequence Rev. 1.4 254 C8051F93x-C8051F92x 22.5.4. Read Sequence (Slave) During a read sequence, an SMBus master reads data from a slave device. The slave in this transfer will be a receiver during the address byte, and a transmitter during all data bytes. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a slave address and direction bit (READ in this case) is received. If hardware ACK generation is disabled, upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The software must respond to the received slave address with an ACK, or ignore the received slave address with a NACK. If hardware ACK generation is enabled, the hardware will apply the ACK for a slave address which matches the criteria set up by SMB0ADR and SMB0ADM. The interrupt will occur after the ACK cycle. If the received slave address is ignored (by software or hardware), slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are transmitted. If the received slave address is acknowledged, data should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 22.8 shows a typical slave read sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. All of the “data byte transferred” interrupts occur after the ACK cycle in this mode, regardless of whether hardware ACK generation is enabled. Interrupts with Hardware ACK Enabled (EHACK = 1) S SLA R A Data Byte A Data Byte N P Interrupts with Hardware ACK Disabled (EHACK = 0) S = START P = STOP N = NACK R = READ SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 22.8. Typical Slave Read Sequence 22.6. SMBus Status Decoding The current SMBus status can be easily decoded using the SMB0CN register. The appropriate actions to take in response to an SMBus event depend on whether hardware slave address recognition and ACK generation is enabled or disabled. Table 22.5 describes the typical actions when hardware slave address recognition and ACK generation is disabled. Table 22.6 describes the typical actions when hardware slave address recognition and ACK generation is enabled. In the tables, STATUS VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. The shown response options are only the typical responses; application-specific procedures are allowed as long as they conform to the SMBus specification. Highlighted responses are allowed by hardware but do not conform to the SMBus specification. 255 Rev. 1.4 C8051F93x-C8051F92x 0 0 1100 0 1000 1 0 A master START was generated. Load slave address + R/W into SMB0DAT. STO ARBLOST 0 X Typical Response Options STA ACKRQ 0 ACK Status Vector Mode Master Transmitter Master Receiver 1110 Current SMbus State 0 0 X 1100 1 0 X 1110 0 1 X - Load next data byte into SMB0DAT. 0 0 X 1100 End transfer with STOP. 0 1 X - 1 X - 0 X 1110 Switch to Master Receiver Mode (clear SI without writing new data 0 to SMB0DAT). 0 X 1000 Acknowledge received byte; Read SMB0DAT. 0 0 1 1000 Send NACK to indicate last byte, 0 and send STOP. 1 0 - Send NACK to indicate last byte, and send STOP followed by 1 START. 1 0 1110 Send ACK followed by repeated START. 1 0 1 1110 Send NACK to indicate last byte, 1 and send repeated START. 0 0 1110 Send ACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). 0 0 1 1100 Send NACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). 0 0 0 1100 A master data or address byte Set STA to restart transfer. 0 was transmitted; NACK Abort transfer. received. A master data or address byte End transfer with STOP and start 1 another transfer. 1 was transmitted; ACK received. Send repeated START. 1 0 X A master data byte was received; ACK requested. ACK Values to Write Values Read Next Status Vector Expected Table 22.5. SMBus Status Decoding With Hardware ACK Generation Disabled (EHACK = 0) Rev. 1.4 256 C8051F93x-C8051F92x Values to Write STA STO 0 0 0 A slave byte was transmitted; No action required (expecting NACK received. STOP condition). 0 0 X 0001 0 0 1 A slave byte was transmitted; Load SMB0DAT with next data ACK received. byte to transmit. 0 0 X 0100 0 1 X A Slave byte was transmitted; No action required (expecting error detected. Master to end transfer). 0 0 X 0001 0 0 X - 0 0 1 0000 If Read, Load SMB0DAT with 0 data byte; ACK received address 0 1 0100 NACK received address. 0 0 0 - If Write, Acknowledge received address 0 0 1 0000 0 1 0100 0 0 - 0 1110 Current SMbus State Typical Response Options An illegal STOP or bus error Clear STO. 0 X X was detected while a Slave Transmission was in progress. If Write, Acknowledge received address 1 0 X A slave address + R/W was received; ACK requested. Slave Receiver 0010 1 Bus Error Condition 257 Reschedule failed transfer; NACK received address. 1 0 Clear STO. 0 0 X - Lost arbitration while attempt- No action required (transfer ing a STOP. complete/aborted). 0 0 0 - Acknowledge received byte; Read SMB0DAT. 0 0 1 0000 NACK received byte. 0 0 0 - 0 0 X - 1 0 X 1110 Abort failed transfer. 0 0 X 1110 0 A STOP was detected while 0 X addressed as a Slave Transmitter or Slave Receiver. 1 1 X 1 A slave byte was received; 0 X ACK requested. 0001 0000 If Read, Load SMB0DAT with Lost arbitration as master; 0 1 X slave address + R/W received; data byte; ACK received address ACK requested. NACK received address. 0 ACK ACK 0101 ARBLOST Status Vector 0100 ACKRQ Slave Transmitter Mode Values Read Next Status Vector Expected Table 22.5. SMBus Status Decoding With Hardware ACK Generation Disabled (EHACK = 0) 0010 0 1 X Lost arbitration while attempt- Abort failed transfer. ing a repeated START. Reschedule failed transfer. 0001 0 1 X Lost arbitration due to a detected STOP. Reschedule failed transfer. 1 0 X 0000 1 1 X Lost arbitration while transmit- Abort failed transfer. ting a data byte as master. Reschedule failed transfer. 0 0 0 - 1 0 0 1110 Rev. 1.4 C8051F93x-C8051F92x 0 0 1100 0 Master Receiver 0 0 0 A master START was generated. Load slave address + R/W into SMB0DAT. 0 0 0 X 1100 1 0 X 1110 0 1 X - Load next data byte into SMB0DAT. 0 0 X 1100 End transfer with STOP. 0 1 X - 1 X - 0 X 1110 0 1 1000 A master data or address byte Set STA to restart transfer. 0 was transmitted; NACK Abort transfer. received. End transfer with STOP and start 1 A master data or address byte another transfer. 1 was transmitted; ACK Send repeated START. 1 received. Switch to Master Receiver Mode (clear SI without writing new data 0 to SMB0DAT). Set ACK for initial data byte. 1 A master data byte was received; ACK sent. 1000 0 STO ARBLOST 0 X Typical Response Options STA ACKRQ 0 ACK Status Vector Mode Master Transmitter 1110 Current SMbus State A master data byte was 0 received; NACK sent (last byte). ACK Values to Write Values Read Next Status Vector Expected Table 22.6. SMBus Status Decoding With Hardware ACK Generation Enabled (EHACK = 1) Set ACK for next data byte; Read SMB0DAT. 0 0 1 1000 Set NACK to indicate next data byte as the last data byte; Read SMB0DAT. 0 0 0 1000 Initiate repeated START. 1 0 0 1110 Switch to Master Transmitter Mode (write to SMB0DAT before 0 clearing SI). 0 X 1100 Read SMB0DAT; send STOP. 0 1 0 - Read SMB0DAT; Send STOP followed by START. 1 1 0 1110 Initiate repeated START. 1 0 0 1110 0 X 1100 Switch to Master Transmitter Mode (write to SMB0DAT before 0 clearing SI). Rev. 1.4 258 C8051F93x-C8051F92x Values to Write STA STO 0 0 0 A slave byte was transmitted; No action required (expecting NACK received. STOP condition). 0 0 X 0001 0 0 1 A slave byte was transmitted; Load SMB0DAT with next data ACK received. byte to transmit. 0 0 X 0100 0 1 X A Slave byte was transmitted; No action required (expecting error detected. Master to end transfer). 0 0 X 0001 0 0 X — If Write, Set ACK for first data byte. 0 0 1 0000 If Read, Load SMB0DAT with data byte 0 0 X 0100 If Write, Set ACK for first data byte. 0 0 1 0000 0 0 X 0100 Reschedule failed transfer 1 0 X 1110 Clear STO. 0 0 X — Lost arbitration while attempt- No action required (transfer ing a STOP. complete/aborted). 0 0 0 — Set ACK for next data byte; Read SMB0DAT. 0 0 1 0000 Set NACK for next data byte; Read SMB0DAT. 0 0 0 0000 0 0 X — 1 0 X 1110 Abort failed transfer. 0 0 X — Current SMbus State Typical Response Options An illegal STOP or bus error Clear STO. 0 X X was detected while a Slave Transmission was in progress. 0 0 X A slave address + R/W was received; ACK sent. Slave Receiver 0010 0 Bus Error Condition 259 0 A STOP was detected while 0 X addressed as a Slave Transmitter or Slave Receiver. 0 1 X 0001 0000 Lost arbitration as master; 1 X slave address + R/W received; If Read, Load SMB0DAT with data byte ACK sent. 0 0 X A slave byte was received. ACK ACK 0101 ARBLOST Status Vector 0100 ACKRQ Slave Transmitter Mode Values Read Next Status Vector Expected Table 22.6. SMBus Status Decoding With Hardware ACK Generation Enabled (EHACK = 1) 0010 0 1 X Lost arbitration while attempt- Abort failed transfer. ing a repeated START. Reschedule failed transfer. 0001 0 1 X Lost arbitration due to a detected STOP. Reschedule failed transfer. 1 0 X 1110 0000 0 1 X Lost arbitration while transmit- Abort failed transfer. ting a data byte as master. Reschedule failed transfer. 0 0 X — 1 0 X 1110 Rev. 1.4 C8051F93x-C8051F92x 23. UART0 UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART. Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details in Section “23.1. Enhanced Baud Rate Generation” on page 261). Received data buffering allows UART0 to start reception of a second incoming data byte before software has finished reading the previous data byte. UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0). The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0 always access the Transmit register. Reads of SBUF0 always access the buffered Receive register; it is not possible to read data from the Transmit register. With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive complete). SFR Bus Write to SBUF TB8 SBUF (TX Shift) SET D Q TX CLR Crossbar Zero Detector Stop Bit Shift Start Data Tx Control Tx Clock Send Tx IRQ SCON TI Serial Port Interrupt MCE REN TB8 RB8 TI RI SMODE UART Baud Rate Generator Port I/O RI Rx IRQ Rx Clock Rx Control Start Shift 0x1FF Load SBUF RB8 Input Shift Register (9 bits) Load SBUF SBUF (RX Latch) Read SBUF SFR Bus RX Crossbar Figure 23.1. UART0 Block Diagram Rev. 1.4 260 C8051F93x-C8051F92x 23.1. Enhanced Baud Rate Generation The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 23.2), which is not useraccessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates. The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to begin any time a START is detected, independent of the TX Timer state. Timer 1 TL1 UART Overflow 2 TX Clock Overflow 2 RX Clock TH1 Start Detected RX Timer Figure 23.2. UART0 Baud Rate Logic Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “25.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload” on page 287). The Timer 1 reload value should be set so that overflows will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an external input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 23.1-A and Equation 23.1-B. A) 1 UartBaudRate = --- × T1_Overflow_Rate 2 B) T1 CLK T1_Overflow_Rate = -------------------------256 – TH1 Equation 23.1. UART0 Baud Rate Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload value). Timer 1 clock frequency is selected as described in Section “25.1. Timer 0 and Timer 1” on page 285. A quick reference for typical baud rates and system clock frequencies is given in Table 23.1 through Table 23.2. Note that the internal oscillator may still generate the system clock when the external oscillator is driving Timer 1. 261 Rev. 1.4 C8051F93x-C8051F92x 23.2. Operational Modes UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown below. TX RS-232 LEVEL XLTR RS-232 RX C8051Fxxx OR TX TX RX RX MCU C8051Fxxx Figure 23.3. UART Interconnect Diagram 23.2.1. 8-Bit UART 8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2). Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits are lost. If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 is set. MARK SPACE START BIT D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT BIT TIMES BIT SAMPLING Figure 23.4. 8-Bit UART Timing Diagram Rev. 1.4 262 C8051F93x-C8051F92x 23.2.2. 9-Bit UART 9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80 (SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the stop bit is ignored. Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to 1. After the stop bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met: (1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to 1. If the above conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to 1. A UART0 interrupt will occur if enabled when either TI0 or RI0 is set to 1. MARK SPACE START BIT D0 D1 D2 D3 D4 D5 D6 D7 D8 STOP BIT BIT TIMES BIT SAMPLING Figure 23.5. 9-Bit UART Timing Diagram 23.3. Multiprocessor Communications 9-Bit UART mode supports multiprocessor communication between a master processor and one or more slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address byte has been received. In the UART interrupt handler, software will compare the received address with the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte. Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s). 263 Rev. 1.4 C8051F93x-C8051F92x Master Device Slave Device Slave Device Slave Device V+ RX TX RX TX RX TX RX TX Figure 23.6. UART Multi-Processor Mode Interconnect Diagram Rev. 1.4 264 C8051F93x-C8051F92x SFR Definition 23.1. SCON0: Serial Port 0 Control Bit 7 6 Name S0MODE Type R/W Reset 0 5 4 3 2 1 0 MCE0 REN0 TB80 RB80 TI0 RI0 R R/W R/W R/W R/W R/W R/W 1 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0x98; Bit-Addressable Bit 7 6 5 Name Function S0MODE Serial Port 0 Operation Mode. Selects the UART0 Operation Mode. 0: 8-bit UART with Variable Baud Rate. 1: 9-bit UART with Variable Baud Rate. Unused Unused. MCE0 Read = 1b. Write = Don’t Care. Multiprocessor Communication Enable. For Mode 0 (8-bit UART): Checks for valid stop bit. 0: Logic level of stop bit is ignored. 1: RI0 will only be activated if stop bit is logic level 1. For Mode 1 (9-bit UART): Multiprocessor Communications Enable. 4 3 2 1 0 REN0 0: Logic level of ninth bit is ignored. 1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1. Receive Enable. TB80 0: UART0 reception disabled. 1: UART0 reception enabled. Ninth Transmission Bit. RB80 The logic level of this bit will be sent as the ninth transmission bit in 9-bit UART Mode (Mode 1). Unused in 8-bit mode (Mode 0). Ninth Receive Bit. TI0 RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th data bit in Mode 1. Transmit Interrupt Flag. RI0 Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8-bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. Receive Interrupt Flag. Set to 1 by hardware when a byte of data has been received by UART0 (set at the STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to 1 causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. 265 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 23.2. SBUF0: Serial (UART0) Port Data Buffer Bit 7 6 5 4 3 2 1 0 SBUF0[7:0] Name Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Page = 0x0; SFR Address = 0x99 Bit Name 7:0 SBUF0 Function Serial Data Buffer Bits 7:0 (MSB–LSB). This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch. Rev. 1.4 266 C8051F93x-C8051F92x Table 23.1. Timer Settings for Standard Baud Rates Using The Internal 24.5 MHz Oscillator SYSCLK from Internal Osc. Frequency: 24.5 MHz Target Baud Rate (bps) Baud Rate % Error Oscillator Divide Factor Timer Clock Source SCA1–SCA0 (pre-scale select)1 T1M1 Timer 1 Reload Value (hex) 230400 –0.32% 106 SYSCLK XX2 1 0xCB 115200 –0.32% 212 SYSCLK XX 1 0x96 57600 0.15% 426 SYSCLK XX 1 0x2B 28800 –0.32% 848 SYSCLK/4 01 0 0x96 14400 0.15% 1704 SYSCLK/12 00 0 0xB9 9600 –0.32% 2544 SYSCLK/12 00 0 0x96 2400 –0.32% 10176 SYSCLK/48 10 0 0x96 1200 0.15% 20448 SYSCLK/48 10 0 0x2B SCA1–SCA0 (pre-scale select)1 T1M1 Timer 1 Reload Value (hex) Notes: 1. SCA1–SCA0 and T1M bit definitions can be found in Section 25.1. 2. X = Don’t care. Table 23.2. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator SYSCLK from Internal Osc. SYSCLK from External Osc. Frequency: 22.1184 MHz Target Baud Rate (bps) Baud Rate % Error Oscilla- Timer Clock tor Divide Source Factor 230400 0.00% 96 SYSCLK XX2 1 0xD0 115200 0.00% 192 SYSCLK XX 1 0xA0 57600 0.00% 384 SYSCLK XX 1 0x40 28800 0.00% 768 SYSCLK / 12 00 0 0xE0 14400 0.00% 1536 SYSCLK / 12 00 0 0xC0 9600 0.00% 2304 SYSCLK / 12 00 0 0xA0 2400 0.00% 9216 SYSCLK / 48 10 0 0xA0 1200 0.00% 18432 SYSCLK / 48 10 0 0x40 230400 0.00% 96 EXTCLK / 8 11 0 0xFA 115200 0.00% 192 EXTCLK / 8 11 0 0xF4 57600 0.00% 384 EXTCLK / 8 11 0 0xE8 28800 0.00% 768 EXTCLK / 8 11 0 0xD0 14400 0.00% 1536 EXTCLK / 8 11 0 0xA0 9600 0.00% 2304 EXTCLK / 8 11 0 0x70 Notes: 1. SCA1–SCA0 and T1M bit definitions can be found in Section 25.1. 2. X = Don’t care. 267 Rev. 1.4 C8051F93x-C8051F92x 24. Enhanced Serial Peripheral Interface (SPI0 and SPI1) The Enhanced Serial Peripheral Interfaces (SPI0 and SPI1) provide access to two identical, flexible, fullduplex synchronous serial busses. Both SPI0 and SPI1 will be referred to collectively as SPIn. SPIn 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 SPIn 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. SFR Bus SYSCLK SPInCN SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT SPIFn WCOLn MODFn RXOVRNn NSSnMD1 NSSnMD0 TXBMTn SPInEN SPInCFG SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 SPInCKR Clock Divide Logic SPI CONTROL LOGIC Data Path Control SPIn IRQ Pin Interface Control MOSI Tx Data SPInDAT SCK Transmit Data Buffer Shift Register 7 6 5 4 3 2 1 0 Rx Data Pin Control Logic Receive Data Buffer MISO C R O S S B A R Port I/O NSS Read SPI0DAT Write SPI0DAT SFR Bus Figure 24.1. SPI Block Diagram Rev. 1.4 268 C8051F93x-C8051F92x 24.1. Signal Descriptions The four signals used by each SPIn (MOSI, MISO, SCK, NSS) are described below. 24.1.1. Master Out, Slave In (MOSI) The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPIn is operating as a master anSPInd an input when SPIn is operating as a slave. Data is transferred most-significant bit first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire mode. 24.1.2. Master In, Slave Out (MISO) The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device. It is used to serially transfer data from the slave to the master. This signal is an input when SPIn is operating as a master and an output when SPIn is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register. 24.1.3. Serial Clock (SCK) The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPIn 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. 24.1.4. Slave Select (NSS) The function of the slave-select (NSS) signal is dependent on the setting of the NSSnMD1 and NSSnMD0 bits in the SPInCN 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: SPIn operates in 3-wire mode, and NSS is disabled. When operating as a slave device, SPIn is always selected in 3-wire mode. Since no select signal is present, SPIn must be the only slave on the bus in 3-wire mode. This is intended for point-to-point communication between a master and one slave. 2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPIn operates in 4-wire mode, and NSS is enabled as an input. When operating as a slave, NSS selects the SPIn device. When operating as a master, a 1-to-0 transition of the NSS signal disables the master function of SPIn so that multiple master devices can be used on the same SPI bus. 3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPIn 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 SPIn as a master device. See Figure 24.2, Figure 24.3, and Figure 24.4 for typical connection diagrams of the various operational modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or 3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will be mapped to a pin on the device. See Section “21. Port Input/Output” on page 216 for general purpose port I/O and crossbar information. 269 Rev. 1.4 C8051F93x-C8051F92x 24.2. SPI Master Mode Operation A SPI master device initiates all data transfers on a SPI bus. SPIn is placed in master mode by setting the Master Enable flag (MSTENn, SPInCN.6). Writing a byte of data to the SPIn data register (SPInDAT) 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 SPIn master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIFn (SPInCN.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 SPIn 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 SPInDAT. When configured as a master, SPIn 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 NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPIn when another master is accessing the bus. When NSS is pulled low in this mode, MSTENn (SPInCN.6) and SPIENn (SPInCN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODFn, SPInCN.5 = 1). Mode Fault will generate an interrupt if enabled. SPIn 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 24.2 shows a connection diagram between two master devices in multiple-master mode. 3-wire single-master mode is active when NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 0. In this mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 24.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSnMD1 (SPInCN.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 NSSnMD0 (SPInCN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 24.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices. Rev. 1.4 270 C8051F93x-C8051F92x Master Device 1 NSS GPIO MISO MISO MOSI MOSI SCK SCK GPIO NSS Master Device 2 Figure 24.2. Multiple-Master Mode Connection Diagram Master Device MISO MISO MOSI MOSI SCK SCK Slave Device Figure 24.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram Master Device GPIO MISO MISO MOSI MOSI SCK SCK NSS NSS MISO MOSI Slave Device Slave Device SCK NSS Figure 24.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram 271 Rev. 1.4 C8051F93x-C8051F92x 24.3. SPI Slave Mode Operation When SPIn 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 SPIn 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 SPInDAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPInDAT. Writes to SPInDAT 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 load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or current) SPI transfer. When configured as a slave, SPIn can be configured for 4-wire or 3-wire operation. The default, 4-wire slave mode, is active when NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 1. In 4-wire mode, the NSS signal is routed to a port pin and configured as a digital input. SPIn 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 24.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master device. 3-wire slave mode is active when NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 0. NSS is not used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPIn must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and reenabling SPIn with the SPIEN bit. Figure 24.3 shows a connection diagram between a slave device in 3wire slave mode and a master device. 24.4. SPI Interrupt Sources When SPIn interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: All of the following bits must be cleared by software. 1. The SPI Interrupt Flag, SPIFn (SPInCN.7) is set to logic 1 at the end of each byte transfer. This flag can occur in all SPIn modes. 2. The Write Collision Flag, WCOLn (SPInCN.6) is set to logic 1 if a write to SPInDAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPInDAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPIn modes. 3. The Mode Fault Flag MODFn (SPInCN.5) is set to logic 1 when SPIn is configured as a master, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTENn and SPIENn bits in SPI0CN are set to logic 0 to disable SPIn and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRNn (SPInCN.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. 1.4 272 C8051F93x-C8051F92x 24.5. Serial Clock Phase and Polarity Four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI Configuration Register (SPInCFG). The CKPHA bit (SPInCFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPInCFG.4) selects between an active-high or active-low clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0 should be disabled (by clearing the SPIENn bit, SPInCN.0) when changing the clock phase or polarity. The clock and data line relationships for master mode are shown in Figure 24.5. For slave mode, the clock and data relationships are shown in Figure 24.6 and Figure 24.7. Note that CKPHA must be set to 0 on both the master and slave SPI when communicating between two of the following devices: C8051F04x, C8051F06x, C8051F12x, C8051F31x, C8051F32x, and C8051F33x. The SPIn Clock Rate Register (SPInCKR) as shown in SFR Definition 24.3 controls the master mode serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz, whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less than 1/10 the system clock frequency. In the special case where the master only wants to transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency. This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s system clock. SCK (CKPOL=0, CKPHA=0) SCK (CKPOL=0, CKPHA=1) SCK (CKPOL=1, CKPHA=0) SCK (CKPOL=1, CKPHA=1) MISO/MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 NSS (Must Remain High in Multi-Master Mode) Figure 24.5. Master Mode Data/Clock Timing 273 Rev. 1.4 Bit 1 Bit 0 C8051F93x-C8051F92x SCK (CKPOL=0, CKPHA=0) SCK (CKPOL=1, CKPHA=0) MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 MISO MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 NSS (4-Wire Mode) Figure 24.6. Slave Mode Data/Clock Timing (CKPHA = 0) SCK (CKPOL=0, CKPHA=1) SCK (CKPOL=1, CKPHA=1) MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 MISO MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Bit 0 NSS (4-Wire Mode) Figure 24.7. Slave Mode Data/Clock Timing (CKPHA = 1) Rev. 1.4 274 C8051F93x-C8051F92x 24.6. SPI Special Function Registers SPI0 and SPI1 are accessed and controlled through four special function registers (8 registers total) in the system controller: SPInCN Control Register, SPInDAT Data Register, SPInCFG Configuration Register, and SPInCKR Clock Rate Register. The special function registers related to the operation of the SPI0 and SPI1 Bus are described in the following figures. 275 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 24.1. SPInCFG: SPI Configuration Bit 7 6 5 4 3 2 1 0 Name SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT Type R R/W R/W R/W R R R R Reset 0 0 0 0 0 1 1 1 SFR Addresses: SPI0CFG = 0xA1, SPI1CFG = 0x84 SFR Pages: SPI0CFG = 0x0, SPI1CFG = 0x0 Bit Name 7 SPIBSY Function SPI Busy. This bit is set to logic 1 when a SPI transfer is in progress (master or slave mode). 6 MSTEN Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. 5 CKPHA SPI Clock Phase. 0: Data centered on first edge of SCK period.* 1: Data centered on second edge of SCK period.* 4 CKPOL SPI Clock Polarity. 0: SCK line low in idle state. 1: SCK line high in idle state. 3 SLVSEL Slave Selected Flag. 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. 2 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. 1 SRMT Shift Register Empty (valid in slave mode only). Set to logic 1 when data has been transferred in/out of the shift register, and there is no data is available to read from the transmit buffer or write to the receive buffer. Set 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 in Master Mode. 0 RXBMT Receive Buffer Empty (valid in slave mode only). 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 in Master Mode. *Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device. See Table 24.1 for timing parameters. Rev. 1.4 276 C8051F93x-C8051F92x SFR Definition 24.2. SPInCN: SPI Control Bit 7 6 Name SPIFn Type R/W R/W Reset 0 0 5 4 3 2 1 0 RXOVRNn NSSnMD1 NSSnMD0 TXBMTn SPInEN R/W R/W R/W R/W R R/W 0 0 0 1 1 0 WCOLn MODFn SFR Addresses: SPI0CN = 0xF8, Bit-Addressable; SPI1CN = 0xB0, Bit-Addressable SFR Pages: SPI0CN = 0x0, SPI1CN = 0x0 Bit Name Function 7 SPIFn SPIn 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 SPIn interrupt service routine. This bit is not automatically cleared by hardware. It must be cleared by software. 6 WCOLn 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. 5 MODFn 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. 4 RXOVRNn Receive Overrun Flag (valid in slave mode only). This bit is set to logic 1 by hardware (and generates a SPIn 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 SPI shift register. This bit is not automatically cleared by hardware. It must be cleared by software. 3:2 NSSnMD[1:0] Slave Select Mode. Selects between the following NSS operation modes: (See Section 24.2 and Section 24.3). 00: 3-Wire Slave or 3-Wire Master Mode. NSS signal is not routed to a port pin. 01: 4-Wire Slave or Multi-Master Mode (Default). NSS is an input to the device. 1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will assume the value of NSSMD0. 1 TXBMTn 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. 0 SPInEN SPIn Enable. 0: SPIn disabled. 1: SPIn enabled. 277 Rev. 1.4 C8051F93x-C8051F92x SFR Definition 24.3. SPInCKR: SPI Clock Rate Bit 7 6 5 4 3 Name SCRn[7:0] Type R/W Reset 0 0 0 0 SFR Addresses: SPI0CKR = 0xA2, SPI1CKR = 0x85 SFR Pages: SPI0CKR = 0x0, SPI1CKR = 0x0 Bit Name 7:0 SCRn 0 2 1 0 0 0 0 Function SPI Clock Rate. These bits determine the frequency of the SCK output when the SPI 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 SPInCKR is the 8-bit value held in the SPInCKR register. SYSCLK f SCK = ----------------------------------------------------------2 × ( SPInCKR[7:0] + 1 ) for 0