C8051F311-GMR

C8051F310/1/2/3/4/5/6/7 8/16 kB ISP Flash MCU Family Analog Peripherals - 10-Bit ADC (C8051F310/1/2/3/6 only) • • • • • - High Speed 8051 µC Core - Pipelined instruction architecture; executes 70% of Up to 200 ksps Up to 21, 17, or 13 external single-ended or differential inputs VREF from external pin or VDD Built-in temperature sensor External conversion start input Comparators • • • Programmable hysteresis and response time Configurable as interrupt or reset source (Comparator0) Low current ( 0.5 µA) On-Chip Debug - On-chip debug circuitry facilitates full speed, - non-intrusive in-system debug  (no emulator required) Provides breakpoints, single stepping,  inspect/modify memory and registers Superior performance to emulation systems using ICE-Chips, target pods, and sockets Complete development kit Supply Voltage 2.7 to 3.6 V - Typical operating current: 5 mA at 25 MHz; - Typical stop mode current: Temperature range: instructions in 1 or 2 system clocks - Up to 25 MIPS throughput with 25 MHz clock - Expanded interrupt handler Memory - 1280 bytes internal data RAM (1024 + 256) - 16 kB (C8051F310/1/6/7) or 8 kB (C8051F312/3/4/5) Flash; In-system programmable in 512-byte sectors Digital Peripherals - 29/25/21 Port I/O;  - All 5 V tolerant with high sink current Hardware enhanced UART, SMBus™, and SPI™ serial ports Four general purpose 16-bit counter/timers 16-bit programmable counter array (PCA) with five capture/compare modules Real time clock capability using PCA or timer and  external clock source Clock Sources - Internal oscillator: 24.5 MHz with ±2% accuracy 11 µA at 32 kHz 0.1 µA –40 to +85 °C - supports crystal-less UART operation External oscillator: Crystal, RC, C, or clock (1 or 2 pin modes) Can switch between clock sources on-the-fly; useful in power saving modes Packages - 32-pin LQFP (C8051F310/2/4) - 28-pin QFN (C8051F311/3/5) - 24-pin QFN (C8051F316/7) A M U X 10-bit 200ksps ADC TEMP SENSOR C8051F310/1/2/3/6 only + + VOLTAGE COMPARATORS DIGITAL I/O UART SMBus SPI PCA Timer 0 Timer 1 Timer 2 Timer 3 CROSSBAR ANALOG PERIPHERALS Port 0 Port 1 Port 2 Port 3 PROGRAMMABLE PRECISION INTERNAL OSCILLATOR HIGH-SPEED CONTROLLER CORE 16 kB/8 kB ISP FLASH 14 INTERRUPTS Rev. 1.8 10/17 8051 CPU (25MIPS) DEBUG CIRCUITRY 1280 B SRAM POR Copyright © 2017 by Silicon Laboratories WDT C8051F31x C8051F310/1/2/3/4/5/6/7 NOTES: 2 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Table Of Contents 1. System Overview.................................................................................................... 17 1.1. CIP-51™ Microcontroller Core.......................................................................... 27 1.1.1. Fully 8051 Compatible.............................................................................. 27 1.1.2. Improved Throughput ............................................................................... 27 1.1.3. Additional Features .................................................................................. 28 1.2. On-Chip Memory............................................................................................... 29 1.3. On-Chip Debug Circuitry................................................................................... 30 1.4. Programmable Digital I/O and Crossbar ........................................................... 31 1.5. Serial Ports ....................................................................................................... 32 1.6. Programmable Counter Array ........................................................................... 32 1.7. 12-Bit Analog to Digital Converter..................................................................... 33 1.8. Comparators ..................................................................................................... 34 2. Absolute Maximum Ratings .................................................................................. 35 3. Global DC Electrical Characteristics .................................................................... 36 4. Pinout and Package Definitions............................................................................ 39 5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only) ........................................................ 51 5.1. Analog Multiplexer ............................................................................................ 51 5.2. Temperature Sensor ......................................................................................... 52 5.3. Modes of Operation .......................................................................................... 54 5.3.1. Starting a Conversion............................................................................... 54 5.3.2. Tracking Modes........................................................................................ 55 5.3.3. Settling Time Requirements ..................................................................... 56 5.4. Programmable Window Detector ...................................................................... 61 5.4.1. Window Detector In Single-Ended Mode ................................................. 63 5.4.2. Window Detector In Differential Mode...................................................... 64 6. Voltage Reference (C8051F310/1/2/3/6 only)........................................................ 67 7. Comparators ........................................................................................................... 69 8. CIP-51 Microcontroller .......................................................................................... 79 8.1. Instruction Set ................................................................................................... 80 8.1.1. Instruction and CPU Timing ..................................................................... 80 8.1.2. MOVX Instruction and Program Memory ................................................. 81 8.2. Memory Organization........................................................................................ 85 8.2.1. Program Memory...................................................................................... 85 8.2.2. Data Memory............................................................................................ 86 8.2.3. General Purpose Registers ...................................................................... 86 8.2.4. Bit Addressable Locations........................................................................ 86 8.2.5. Stack ....................................................................................................... 86 8.2.6. Special Function Registers....................................................................... 87 8.2.7. Register Descriptions ............................................................................... 90 8.3. Interrupt Handler ............................................................................................... 93 8.3.1. MCU Interrupt Sources and Vectors ........................................................ 94 8.3.2. External Interrupts .................................................................................... 95 8.3.3. Interrupt Priorities ..................................................................................... 95 Rev. 1.8 3 C8051F310/1/2/3/4/5/6/7 8.3.4. Interrupt Latency ...................................................................................... 95 8.3.5. Interrupt Register Descriptions................................................................. 97 8.4. Power Management Modes ............................................................................ 102 8.4.1. Idle Mode................................................................................................ 102 8.4.2. Stop Mode .............................................................................................. 103 9. Reset Sources....................................................................................................... 105 9.1. Power-On Reset ............................................................................................. 106 9.2. Power-Fail Reset / VDD Monitor..................................................................... 106 9.3. External Reset ................................................................................................ 107 9.4. Missing Clock Detector Reset......................................................................... 108 9.5. Comparator0 Reset......................................................................................... 108 9.6. PCA Watchdog Timer Reset........................................................................... 108 9.7. Flash Error Reset............................................................................................ 108 9.8. Software Reset ............................................................................................... 108 10. Flash Memory ..................................................................................................... 111 10.1.Programming The Flash Memory ................................................................... 111 10.1.1.Flash Lock and Key Functions ............................................................... 111 10.1.2.Flash Erase Procedure .......................................................................... 111 10.1.3.Flash Write Procedure ........................................................................... 112 10.2.Non-volatile Data Storage .............................................................................. 112 10.3.Security Options ............................................................................................. 113 10.4.Flash Write and Erase Guidelines .................................................................. 115 10.4.1.VDD Maintenance and the VDD Monitor ................................................. 115 10.4.2.PSWE Maintenance ............................................................................... 115 10.4.3.System Clock ......................................................................................... 116 11. External RAM ........................................................................................................ 119 12. Oscillators ............................................................................................................. 121 12.1.Programmable Internal Oscillator ................................................................... 121 12.2.External Oscillator Drive Circuit...................................................................... 124 12.3.System Clock Selection.................................................................................. 124 12.4.External Crystal Example ............................................................................... 126 12.5.External RC Example ..................................................................................... 127 12.6.External Capacitor Example ........................................................................... 127 13. Port Input/Output ................................................................................................ 129 13.1.Priority Crossbar Decoder .............................................................................. 131 13.2.Port I/O Initialization ....................................................................................... 133 13.3.General Purpose Port I/O ............................................................................... 135 14. SMBus ................................................................................................................... 145 14.1.Supporting Documents ................................................................................... 146 14.2.SMBus Configuration...................................................................................... 146 14.3.SMBus Operation ........................................................................................... 146 14.3.1.Arbitration............................................................................................... 147 14.3.2.Clock Low Extension.............................................................................. 148 14.3.3.SCL Low Timeout................................................................................... 148 14.3.4.SCL High (SMBus Free) Timeout .......................................................... 148 4 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14.4.Using the SMBus............................................................................................ 149 14.4.1.SMBus Configuration Register............................................................... 150 14.4.2.SMB0CN Control Register ..................................................................... 153 14.4.3.Data Register ......................................................................................... 156 14.5.SMBus Transfer Modes.................................................................................. 157 14.5.1.Master Transmitter Mode ....................................................................... 157 14.5.2.Master Receiver Mode ........................................................................... 158 14.5.3.Slave Receiver Mode ............................................................................. 159 14.5.4.Slave Transmitter Mode ......................................................................... 160 14.6.SMBus Status Decoding................................................................................. 161 15. UART0.................................................................................................................... 163 15.1.Enhanced Baud Rate Generation................................................................... 164 15.2.Operational Modes ......................................................................................... 165 15.2.1.8-Bit UART ............................................................................................. 165 15.2.2.9-Bit UART ............................................................................................. 166 15.3.Multiprocessor Communications .................................................................... 167 16. Enhanced Serial Peripheral Interface (SPI0)...................................................... 173 16.1.Signal Descriptions......................................................................................... 174 16.1.1.Master Out, Slave In (MOSI).................................................................. 174 16.1.2.Master In, Slave Out (MISO).................................................................. 174 16.1.3.Serial Clock (SCK) ................................................................................. 174 16.1.4.Slave Select (NSS) ................................................................................ 174 16.2.SPI0 Master Mode Operation ......................................................................... 175 16.3.SPI0 Slave Mode Operation ........................................................................... 177 16.4.SPI0 Interrupt Sources ................................................................................... 177 16.5.Serial Clock Timing......................................................................................... 178 16.6.SPI Special Function Registers ...................................................................... 180 17. Timers ................................................................................................................... 187 17.1.Timer 0 and Timer 1 ....................................................................................... 187 17.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 187 17.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 189 17.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 189 17.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 190 17.2.Timer 2 .......................................................................................................... 195 17.2.1.16-bit Timer with Auto-Reload................................................................ 195 17.2.2.8-bit Timers with Auto-Reload................................................................ 196 17.3.Timer 3 .......................................................................................................... 199 17.3.1.16-bit Timer with Auto-Reload................................................................ 199 17.3.2.8-bit Timers with Auto-Reload................................................................ 200 18. Programmable Counter Array ............................................................................ 203 18.1.PCA Counter/Timer ........................................................................................ 204 18.2.Capture/Compare Modules ............................................................................ 205 18.2.1.Edge-triggered Capture Mode................................................................ 206 18.2.2.Software Timer (Compare) Mode........................................................... 207 Rev. 1.8 5 C8051F310/1/2/3/4/5/6/7 18.2.3.High-Speed Output Mode ...................................................................... 208 18.2.4.Frequency Output Mode ........................................................................ 209 18.2.5.8-Bit Pulse Width Modulator Mode......................................................... 210 18.2.6.16-Bit Pulse Width Modulator Mode....................................................... 211 18.3.Watchdog Timer Mode ................................................................................... 212 18.3.1.Watchdog Timer Operation .................................................................... 212 18.3.2.Watchdog Timer Usage ......................................................................... 213 18.4.Register Descriptions for PCA........................................................................ 215 19. Revision Specific Behavior ................................................................................. 221 19.1.Revision Identification..................................................................................... 221 19.2.Reset Behavior ............................................................................................... 221 19.2.1.Weak Pullups on GPIO Pins .................................................................. 221 19.2.2.VDD Monitor and the RST Pin ............................................................... 221 19.3.PCA Counter .................................................................................................. 222 20. C2 Interface ........................................................................................................... 223 20.1.C2 Interface Registers.................................................................................... 223 20.2.C2 Pin Sharing ............................................................................................... 225 Document Change List............................................................................................. 226 Contact Information.................................................................................................. 228 6 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 List of Figures 1. System Overview Figure 1.1. C8051F310 Block Diagram .................................................................... 19 Figure 1.2. C8051F311 Block Diagram .................................................................... 20 Figure 1.3. C8051F312 Block Diagram .................................................................... 21 Figure 1.4. C8051F313 Block Diagram .................................................................... 22 Figure 1.5. C8051F314 Block Diagram .................................................................... 23 Figure 1.6. C8051F315 Block Diagram .................................................................... 24 Figure 1.7. C8051F316 Block Diagram .................................................................... 25 Figure 1.8. C8051F317 Block Diagram .................................................................... 26 Figure 1.9. Comparison of Peak MCU Execution Speeds ....................................... 27 Figure 1.10. On-Chip Clock and Reset..................................................................... 28 Figure 1.11. On-Board Memory Map........................................................................ 29 Figure 1.12. Development/In-System Debug Diagram............................................. 30 Figure 1.13. Digital Crossbar Diagram ..................................................................... 31 Figure 1.14. PCA Block Diagram.............................................................................. 32 Figure 1.15. 12-Bit ADC Block Diagram ................................................................... 33 Figure 1.16. Comparator0 Block Diagram ................................................................ 34 2. Absolute Maximum Ratings 3. Global DC Electrical Characteristics 4. Pinout and Package Definitions Figure 4.1. LQFP-32 Pinout Diagram (Top View) .................................................... 41 Figure 4.2. LQFP-32 Package Diagram ................................................................... 42 Figure 4.3. Typical LQFP-32 Landing Diagram........................................................ 43 Figure 4.4. QFN-28 Pinout Diagram (Top View) ...................................................... 44 Figure 4.5. QFN-28 Package Drawing ..................................................................... 45 Figure 4.6. Typical QFN-28 Landing Diagram.......................................................... 46 Figure 4.7. QFN-24 Pinout Diagram (Top View) ...................................................... 47 Figure 4.8. QFN-24 Package Drawing ..................................................................... 48 Figure 4.9. Typical QFN-24 Landing Diagram.......................................................... 49 Figure 4.10. QFN-24 Solder Paste Recommendation.............................................. 50 5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only) Figure 5.1. ADC0 Functional Block Diagram............................................................ 51 Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 52 Figure 5.3. Temperature Sensor Error with 1-Point Calibration ............................... 53 Figure 5.4. 12-Bit ADC Track and Conversion Example Timing .............................. 55 Figure 5.5. ADC0 Equivalent Input Circuits.............................................................. 56 Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data ... 63 Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data ..... 63 Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data ....... 64 Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data.......... 64 6. Voltage Reference (C8051F310/1/2/3/6 only) Figure 6.1. Voltage Reference Functional Block Diagram ....................................... 67 Rev. 1.8 7 C8051F310/1/2/3/4/5/6/7 7. Comparators Figure 7.1. Comparator0 Functional Block Diagram ................................................ 69 Figure 7.2. Comparator1 Functional Block Diagram ................................................ 70 Figure 7.3. Comparator Hysteresis Plot ................................................................... 71 8. CIP-51 Microcontroller Figure 8.1. CIP-51 Block Diagram............................................................................ 79 Figure 8.2. Memory Map .......................................................................................... 85 9. Reset Sources Figure 9.1. Reset Sources...................................................................................... 105 Figure 9.2. Power-On and VDD Monitor Reset Timing .......................................... 106 10. Flash Memory Figure 10.1. Flash Program Memory Map.............................................................. 113 11. External RAM 12. Oscillators Figure 12.1. Oscillator Diagram.............................................................................. 121 Figure 12.2. 32.768 kHz External Crystal Example................................................ 126 13. Port Input/Output Figure 13.1. Port I/O Functional Block Diagram ..................................................... 129 Figure 13.2. Port I/O Cell Block Diagram ............................................................... 130 Figure 13.3. Crossbar Priority Decoder with No Pins Skipped ............................... 131 Figure 13.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 132 14. SMBus Figure 14.1. SMBus Block Diagram ....................................................................... 145 Figure 14.2. Typical SMBus Configuration ............................................................. 146 Figure 14.3. SMBus Transaction ............................................................................ 147 Figure 14.4. Typical SMBus SCL Generation......................................................... 151 Figure 14.5. Typical Master Transmitter Sequence................................................ 157 Figure 14.6. Typical Master Receiver Sequence.................................................... 158 Figure 14.7. Typical Slave Receiver Sequence...................................................... 159 Figure 14.8. Typical Slave Transmitter Sequence.................................................. 160 15. UART0 Figure 15.1. UART0 Block Diagram ....................................................................... 163 Figure 15.2. UART0 Baud Rate Logic .................................................................... 164 Figure 15.3. UART Interconnect Diagram .............................................................. 165 Figure 15.4. 8-Bit UART Timing Diagram............................................................... 165 Figure 15.5. 9-Bit UART Timing Diagram............................................................... 166 Figure 15.6. UART Multi-Processor Mode Interconnect Diagram .......................... 167 16. Enhanced Serial Peripheral Interface (SPI0) Figure 16.1. SPI Block Diagram ............................................................................. 173 Figure 16.2. Multiple-Master Mode Connection Diagram ....................................... 176 Figure 16.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 176 Figure 16.4. 4-Wire Single Master and Slave Mode Connection Diagram ............. 176 Figure 16.5. Master Mode Data/Clock Timing ........................................................ 178 Figure 16.6. Slave Mode Data/Clock Timing (CKPHA = 0) .................................... 179 Figure 16.7. Slave Mode Data/Clock Timing (CKPHA = 1) .................................... 179 8 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Figure 16.8. SPI Master Timing (CKPHA = 0)........................................................ 183 Figure 16.9. SPI Master Timing (CKPHA = 1)........................................................ 183 Figure 16.10. SPI Slave Timing (CKPHA = 0)........................................................ 184 Figure 16.11. SPI Slave Timing (CKPHA = 1)........................................................ 184 17. Timers Figure 17.1. T0 Mode 0 Block Diagram.................................................................. 188 Figure 17.2. T0 Mode 2 Block Diagram.................................................................. 189 Figure 17.3. T0 Mode 3 Block Diagram.................................................................. 190 Figure 17.4. Timer 2 16-Bit Mode Block Diagram .................................................. 195 Figure 17.5. Timer 2 8-Bit Mode Block Diagram .................................................... 196 Figure 17.6. Timer 3 16-Bit Mode Block Diagram .................................................. 199 Figure 17.7. Timer 3 8-Bit Mode Block Diagram .................................................... 200 18. Programmable Counter Array Figure 18.1. PCA Block Diagram............................................................................ 203 Figure 18.2. PCA Counter/Timer Block Diagram.................................................... 204 Figure 18.3. PCA Interrupt Block Diagram ............................................................. 205 Figure 18.4. PCA Capture Mode Diagram.............................................................. 206 Figure 18.5. PCA Software Timer Mode Diagram .................................................. 207 Figure 18.6. PCA High Speed Output Mode Diagram............................................ 208 Figure 18.7. PCA Frequency Output Mode ............................................................ 209 Figure 18.8. PCA 8-Bit PWM Mode Diagram ......................................................... 210 Figure 18.9. PCA 16-Bit PWM Mode...................................................................... 211 Figure 18.10. PCA Module 4 with Watchdog Timer Enabled ................................. 212 19. Revision Specific Behavior Figure 19.1. Reading Package Marking ................................................................. 221 20. C2 Interface Figure 20.1. Typical C2 Pin Sharing....................................................................... 225 Rev. 1.8 9 C8051F310/1/2/3/4/5/6/7 NOTES: 10 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 List of Tables 1. System Overview Table 1.1. Product Selection Guide ......................................................................... 18 2. Absolute Maximum Ratings Table 2.1. Absolute Maximum Ratings* .................................................................. 35 3. Global DC Electrical Characteristics Table 3.1. Global DC Electrical Characteristics ....................................................... 36 Table 3.2. Electrical Characteristics Quick Reference ............................................ 38 4. Pinout and Package Definitions Table 4.1. Pin Definitions for the C8051F31x .......................................................... 39 Table 4.2. LQFP-32 Package Dimensions .............................................................. 42 Table 4.3. LQFP-32 Landing Pattern Dimensions ................................................... 43 Table 4.4. QFN-28 Package Dimensions ................................................................ 45 Table 4.5. QFN-28 Landing Pattern Dimensions ..................................................... 46 Table 4.6. QFN-24 Package Dimensions ................................................................ 48 5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only) Table 5.1. ADC0 Electrical Characteristics .............................................................. 65 6. Voltage Reference (C8051F310/1/2/3/6 only) Table 6.1. External Voltage Reference Circuit Electrical Characteristics ................ 68 7. Comparators Table 7.1. Comparator Electrical Characteristics .................................................... 78 8. CIP-51 Microcontroller Table 8.1. CIP-51 Instruction Set Summary ............................................................ 81 Table 8.2. Special Function Register (SFR) Memory Map ...................................... 87 Table 8.3. Special Function Registers ..................................................................... 88 Table 8.4. Interrupt Summary .................................................................................. 96 9. Reset Sources Table 9.1. Reset Electrical Characteristics ............................................................ 110 10. Flash Memory Table 10.1. Flash Electrical Characteristics .......................................................... 112 Table 10.2. Flash Security Summary .................................................................... 114 11. External RAM 12. Oscillators Table 12.1. Internal Oscillator Electrical Characteristics ....................................... 123 13. Port Input/Output Table 13.1. Port I/O DC Electrical Characteristics ................................................ 143 14. SMBus Table 14.1. SMBus Clock Source Selection .......................................................... 150 Table 14.2. Minimum SDA Setup and Hold Times ................................................ 151 Rev. 1.8 11 C8051F310/1/2/3/4/5/6/7 Table 14.3. Sources for Hardware Changes to SMB0CN ..................................... 155 Table 14.4. SMBus Status Decoding ..................................................................... 161 15. UART0 Table 15.1. Timer Settings for Standard Baud Rates  Using the Internal Oscillator ............................................................... 170 Table 15.2. Timer Settings for Standard Baud Rates  Using an External 25 MHz Oscillator .................................................. 170 Table 15.3. Timer Settings for Standard Baud Rates  Using an External 22.1184 MHz Oscillator ......................................... 171 Table 15.4. Timer Settings for Standard Baud Rates  Using an External 18.432 MHz Oscillator ........................................... 171 Table 15.5. Timer Settings for Standard Baud Rates  Using an External 11.0592 MHz Oscillator ......................................... 172 Table 15.6. Timer Settings for Standard Baud Rates  Using an External 3.6864 MHz Oscillator ........................................... 172 16. Enhanced Serial Peripheral Interface (SPI0) Table 16.1. SPI Slave Timing Parameters ............................................................ 185 17. Timers 18. Programmable Counter Array Table 18.1. PCA Timebase Input Options ............................................................. 204 Table 18.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 205 Table 18.3. Watchdog Timer Timeout Intervals1 .................................................................. 214 19. Revision Specific Behavior 20. C2 Interface 12 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 List of Registers SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select . . . . . . . . . . . . . . . . . . . 57 SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select . . . . . . . . . . . . . . . . . . 58 SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 SFR Definition 5.4. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 59 SFR Definition 5.5. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 SFR Definition 5.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 61 SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 61 SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 62 SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . . 62 SFR Definition 6.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 SFR Definition 7.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 73 SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 74 SFR Definition 7.4. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 76 SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 77 SFR Definition 8.1. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 SFR Definition 8.2. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 SFR Definition 8.3. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 SFR Definition 8.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 SFR Definition 8.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 SFR Definition 8.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 SFR Definition 8.7. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 SFR Definition 8.8. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 SFR Definition 8.9. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . . 99 SFR Definition 8.10. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . 100 SFR Definition 8.11. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . 101 SFR Definition 8.12. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 SFR Definition 9.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . . 107 SFR Definition 9.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 SFR Definition 10.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 116 SFR Definition 10.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 SFR Definition 10.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 SFR Definition 11.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 119 SFR Definition 12.1. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 122 SFR Definition 12.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 122 SFR Definition 12.3. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 SFR Definition 12.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 125 SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 134 SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 135 SFR Definition 13.3. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 SFR Definition 13.4. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Rev. 1.8 13 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 137 SFR Definition 13.6. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 SFR Definition 13.7. P1: Port1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 SFR Definition 13.8. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 SFR Definition 13.9. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 139 SFR Definition 13.10. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 SFR Definition 13.11. P2: Port2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 SFR Definition 13.12. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 SFR Definition 13.13. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 141 SFR Definition 13.14. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 SFR Definition 13.15. P3: Port3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 SFR Definition 13.16. P3MDIN: Port3 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 SFR Definition 13.17. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 143 SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 152 SFR Definition 14.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 SFR Definition 14.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 SFR Definition 15.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 168 SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 169 SFR Definition 16.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 180 SFR Definition 16.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 SFR Definition 16.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 SFR Definition 16.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 SFR Definition 17.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 SFR Definition 17.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 SFR Definition 17.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 SFR Definition 17.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 SFR Definition 17.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 SFR Definition 17.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 SFR Definition 17.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 SFR Definition 17.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 SFR Definition 17.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 198 SFR Definition 17.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 198 SFR Definition 17.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 SFR Definition 17.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 SFR Definition 17.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 SFR Definition 17.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 202 SFR Definition 17.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 202 SFR Definition 17.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 SFR Definition 17.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 SFR Definition 18.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 SFR Definition 18.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 SFR Definition 18.3. PCA0CPMn: PCA Capture/Compare Mode Registers . . . . . . . 217 SFR Definition 18.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 218 SFR Definition 18.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 218 SFR Definition 18.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 218 14 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 18.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 219 C2 Register Definition 20.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 C2 Register Definition 20.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 223 C2 Register Definition 20.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 224 C2 Register Definition 20.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 224 C2 Register Definition 20.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 224 Rev. 1.8 15 C8051F310/1/2/3/4/5/6/7 NOTES: 16 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 1. System Overview C8051F31x devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are listed below. Refer to Table 1.1 for specific product feature selection. • • • • • • • • • • • • High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS) In-system, full-speed, non-intrusive debug interface (on-chip) True 12-bit 200 ksps 25-channel single-ended/differential ADC with analog multiplexer (C8051F310/1/2/3/6) Precision programmable 25 MHz internal oscillator 16k kB (C8051F310/1/6/7) or 8 kB (C8051F312/3/4/5) of on-chip Flash memory 1280 bytes of on-chip RAM SMBus/I2C, Enhanced UART, and Enhanced SPI serial interfaces implemented in hardware Four general-purpose 16-bit timers Programmable Counter/Timer Array (PCA) with five capture/compare modules and Watchdog Timer function On-chip Power-On Reset, VDD Monitor, and Temperature Sensor On-chip Voltage Comparators (2) 29/25/21 Port I/O (5 V tolerant) With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F31x 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 programming and debugging without occupying package pins. Each device is specified for 2.7-to-3.6 V operation over the industrial temperature range (–45 to +85 °C). The Port I/O and RST pins are tolerant of input signals up to 5 V. The C8051F31x are available in 32-pin LQFP, 28-pin QFN, and 24-pin QFN packages. See Table 1.1 for ordering part numbers. Note: QFN packages are also referred to as MLP or MLF packages. Rev. 1.8 17 C8051F310/1/2/3/4/5/6/7 Flash Memory RAM Calibrated Internal 24.5 MHz Oscillator SMBus/I2C Enhanced SPI UART Timers (16-bit) Programmable Counter Array Digital Port I/Os 10-bit 200 ksps ADC Temperature Sensor Analog Comparators Lead-free (RoHS Compliant) Package C8051F310 25 16 1280       29   2 - LQFP-32 C8051F310-GQ 25 16 1280       29   2  LQFP-32 C8051F311 25 16 1280       25   2 - QFN-28 C8051F311-GM 25 16 1280       25   2  QFN-28 C8051F312 25 8 1280       29   2 - LQFP-32 C8051F312-GQ 25 8 1280       29   2  LQFP-32 C8051F313 25 8 1280       25   2 - QFN-28 C8051F313-GM 25 8 1280       25   2  QFN-28 C8051F314 25 8 1280       29 - - 2 - LQFP-32 C8051F314-GQ 25 8 1280       29 - - 2  LQFP-32 C8051F315 25 8 1280       25 - - 2 - QFN-28 C8051F315-GM 25 8 1280       25 - - 2  QFN-28 C8051F316-GM 25 16 1280       21   2  QFN-24 C8051F317-GM 25 16 1280       21 - - 2  QFN-24 Ordering Part Number MIPS (Peak) Table 1.1. Product Selection Guide 18 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 16kbyte FLASH 256 byte SRAM PCA/ WDT 1K byte SRAM System Clock C R O S S B A R Timer 0,1,2,3 / RTC SMBus C o SFR Bus r e P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch VDD D r v CP0 + - CP1 + - P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D P3.1 P3.2 P3.3 P3.4 VREF Temp 10-bit 200ksps ADC A M U X AIN0-AIN20 VDD Figure 1.1. C8051F310 Block Diagram Rev. 1.8 19 C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 16kbyte FLASH 256 byte SRAM 1K byte SRAM System Clock C o SFR Bus r e C R O S S B A R Timer 0,1,2,3 / RTC PCA/ WDT SMBus P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch VDD D r v CP0 + - CP1 + - VREF Temp 10-bit 200ksps ADC A M U X VDD Figure 1.2. C8051F311 Block Diagram 20 Rev. 1.8 AIN0-AIN20 P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 8 kB FLASH 256 byte SRAM PCA/ WDT 1K byte SRAM System Clock C R O S S B A R Timer 0,1,2,3 / RTC SMBus C o SFR Bus r e P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch VDD D r v CP0 + - CP1 + - P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D P3.1 P3.2 P3.3 P3.4 VREF Temp 10-bit 200ksps ADC A M U X AIN0-AIN20 VDD Figure 1.3. C8051F312 Block Diagram Rev. 1.8 21 C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 8 kB FLASH 256 byte SRAM 1K byte SRAM System Clock C o SFR Bus r e C R O S S B A R Timer 0,1,2,3 / RTC PCA/ WDT SMBus P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch VDD D r v CP0 + - CP1 + - VREF Temp 10-bit 200ksps ADC A M U X VDD Figure 1.4. C8051F313 Block Diagram 22 Rev. 1.8 AIN0-AIN20 P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 8 kB FLASH 256 byte SRAM 1K byte SRAM System Clock C R O S S B A R Timer 0,1,2,3 / RTC PCA/ WDT SMBus C o SFR Bus r e P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch D r v CP0 + - CP1 + - P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D P3.1 P3.2 P3.3 P3.4 Figure 1.5. C8051F314 Block Diagram Rev. 1.8 23 C8051F310/1/2/3/4/5/6/7 VDD Analog/Digital Power Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 8 kB FLASH 256 byte SRAM 1K byte SRAM System Clock C o SFR Bus r e C R O S S B A R Timer 0,1,2,3 / RTC PCA/ WDT SMBus D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch Figure 1.6. C8051F315 Block Diagram 24 P 1 Rev. 1.8 D r v CP0 + - CP1 + - P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P2.6 P2.7 P3.0/C2D C8051F310/1/2/3/4/5/6/7 Analog/Digital Power VDD Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 16 kB FLASH 256 byte SRAM PCA/ WDT 1 kB SRAM System Clock C R O S S B A R Timer 0,1,2,3 / RTC SMBus C o SFR Bus r e P 1 D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch VDD P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P3.0/C2D D r v CP0 + - CP1 + - VREF Temp 10-bit 200 ksps ADC A M U X AIN0–AIN20 VDD Figure 1.7. C8051F316 Block Diagram Rev. 1.8 25 C8051F310/1/2/3/4/5/6/7 Analog/Digital Power VDD Port 0 Latch P 0 Port 1 Latch D r v GND UART C2D Debug HW Reset /RST/C2CK POR XTAL1 XTAL2 External Oscillator Circuit 2% Internal Oscillator BrownOut 8 0 5 1 16 kB FLASH 256 byte SRAM 1 kB SRAM System Clock C o SFR Bus r e C R O S S B A R Timer 0,1,2,3 / RTC PCA/ WDT SMBus D r v P 2 SPI D r v Port 2 Latch P 3 Port 3 Latch Figure 1.8. C8051F317 Block Diagram 26 P 1 Rev. 1.8 D r v CP0 + - CP1 + - P0.0/VREF P0.1 P0.2/XTAL1 P0.3/XTAL2 P0.4/TX P0.5/RX P0.6/CNVST P0.7 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 P3.0/C2D C8051F310/1/2/3/4/5/6/7 1.1. CIP-51™ Microcontroller Core 1.1.1. Fully 8051 Compatible The C8051F31x family utilizes Silicon Laboratories' proprietary CIP-51 microcontroller core. The CIP-51 is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The CIP-51 core offers all the peripherals included with a standard 8052, including four 16-bit counter/timers, a full-duplex UART with extended baud rate configuration, an enhanced SPI port, 1280 bytes of internal RAM, 128 byte Special Function Register (SFR) address space, and 29/25/21 I/O pins. 1.1.2. Improved Throughput The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than four system clock cycles. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute 1 2 2/3 3 3/4 4 4/5 5 8 Number of Instructions 26 50 5 14 7 3 1 2 1 With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. Figure 1.9 shows a comparison of peak throughputs for various 8-bit microcontroller cores with their maximum system clocks. 25 MIPS 20 15 10 5 Silicon Labs Microchip Philips ADuC812 CIP-51 PIC17C75x 80C51 8051 (25 MHz clk) (33 MHz clk) (33 MHz clk) (16 MHz clk) Figure 1.9. Comparison of Peak MCU Execution Speeds Rev. 1.8 27 C8051F310/1/2/3/4/5/6/7 1.1.3. Additional Features The C8051F31x 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 14 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051), 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 VRST as given in Table 9.1 on page 110), a Watchdog Timer, a Missing Clock Detector, a voltage level detection from Comparator0, a forced software reset, an external reset pin, and an errant Flash read/write protection circuit. Each reset source except for the POR, Reset Input Pin, or Flash error may be disabled by the user in software. The WDT may be permanently enabled in software after a power-on reset during MCU initialization. The internal oscillator is factory calibrated to 24.5 MHz ±2%. An external oscillator drive circuit is also included, allowing an external crystal, ceramic resonator, capacitor, RC, or CMOS clock source to generate the system clock. If desired, the system clock source may be switched on-the-fly between the internal and external oscillator circuits. An external oscillator can be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switching to the fast internal oscillator as needed. VDD Power On Reset Supply Monitor Px.x Px.x + - Comparator 0 '0' Enable (wired-OR) + C0RSEF Missing Clock Detector (oneshot) EN Reset Funnel PCA WDT (Software Reset) SWRSF Errant FLASH Operation Internal Oscillator XTAL1 XTAL2 External Oscillator Drive System Clock Clock Select WDT Enable MCD Enable EN CIP-51 Microcontroller Core System Reset Extended Interrupt Handler Figure 1.10. On-Chip Clock and Reset 28 Rev. 1.8 /RST C8051F310/1/2/3/4/5/6/7 1.2. On-Chip Memory The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of general purpose registers, and the next 16 bytes can be byte addressable or bit addressable. Program memory consists of 8 or 16k kB of Flash. This memory may be reprogrammed in-system in 512 byte sectors, and requires no special off-chip programming voltage. See Figure 1.11 for the MCU system memory map. DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE PROGRAM/DATA MEMORY (Flash) C8051F310/1/6/7 0x3E00 0x3DFF 0xFF RESERVED 0x80 0x7F Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) 16 kB Flash (In-System Programmable in 512 Byte Sectors) 0x30 0x2F 0x20 0x1F 0x00 Bit Addressable Special Function Register's (Direct Addressing Only) Lower 128 RAM (Direct and Indirect Addressing) General Purpose Registers EXTERNAL DATA ADDRESS SPACE 0x0000 0xFFFF C8051F312/3/4/5 0x2000 0x1FFF RESERVED Same 1024 bytes as from 0x0000 to 0x03FF, wrapped on 1 kB boundaries 8 kB Flash (In-System Programmable in 512 Byte Sectors) 0x0400 0x03FF 0x0000 XRAM - 1024 Bytes (accessable using MOVX instruction) 0x0000 Figure 1.11. On-Board Memory Map Rev. 1.8 29 C8051F310/1/2/3/4/5/6/7 1.3. On-Chip Debug Circuitry The C8051F31x devices include on-chip Silicon Labs 2-Wire (C2) debug circuitry that provides non-intrusive, full speed, in-circuit debugging of the production part installed in the end application. Silicon Labs' debugging system supports inspection and modification of memory and registers, breakpoints, and single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized. The C8051F310DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F31x MCUs. The kit includes software with a developer's studio and debugger, an integrated 8051 assembler, a debug adapter, a target application board with the associated MCU installed, and the required cables and wall-mount power supply. The Silicon Labs IDE interface is a vastly superior developing and debugging configuration, compared to standard MCU emulators that use on-board "ICE Chips" and require the MCU in the application board to be socketed. Silicon Labs' debug paradigm increases ease of use and preserves the performance of the precision analog peripherals. Silicon Laboratories Integrated Development Environment Windows 98SE or later Debug Adapter C2 (x2), VDD, GND VDD TARGET PCB GND C8051F31x Figure 1.12. Development/In-System Debug Diagram 30 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 1.4. Programmable Digital I/O and Crossbar C8051F310/2/4 devices include 29 I/O pins (three byte-wide Ports and one 5-bit-wide Port); C8051F311/3/5 devices include 25 I/O pins (three byte-wide Ports and one 1-bit-wide Port); C8051F316/7 devices include 21 I/O pins (one byte-wide Port, two 6-bit-wide Ports and one 1-bit-wide Port). The C8051F31x Ports behave like typical 8051 Ports with a few enhancements. Each Port pin may be configured as an analog input or a digital I/O pin. Pins selected as digital I/Os may additionally be configured for push-pull or open-drain output. The “weak pullups” that are fixed on typical 8051 devices may be globally disabled, providing power savings capabilities. The Digital Crossbar allows mapping of internal digital system resources to Port I/O pins (See Figure 1.13). On-chip counter/timers, serial buses, HW interrupts, comparator output, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in the Crossbar Control registers. This allows the user to select the exact mix of general purpose Port I/O and digital resources needed for the particular application. XBR0, XBR1, PnSKIP Registers PnMDOUT, PnMDIN Registers Priority Decoder Highest Priority UART 4 SPI (Internal Digital Signals) 2 SMBus 8 P0 I/O Cells P0.0 P1 I/O Cells P1.0 P2 I/O Cells P2.0 CP0 Outputs 2 CP1 Outputs 2 Digital Crossbar 8 4 8 SYSCLK P3 I/O Cells P3.0 4 P1.7 P2.7 6 PCA 5 Lowest Priority P0.7 2 T0, T1 2 P3.4 8 P0 (P0.0-P0.7) P1 (P1.0-P1.7) Notes: 1. P3.1–P3.4 only available on the C8051F310/2/4. 2. P1.6, P1.7, P2.6, P2.7 only available on the C8051F310/1/2/3/4/5 (Port Latches) 8 4 (P2.0-P2.3) P2 4 (P2.4-P2.7) 5 P3 (P3.0-P3.4) Figure 1.13. Digital Crossbar Diagram Rev. 1.8 31 C8051F310/1/2/3/4/5/6/7 1.5. Serial Ports The C8051F31x Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud rate configuration, and an Enhanced SPI interface. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention. 1.6. 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 five 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. The external clock source selection is useful for real-time clock functionality, where the PCA is clocked by an external source while the internal oscillator drives the system clock. Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture, Software Timer, High Speed Output, 8- or 16-bit Pulse Width Modulator, or Frequency Output. Additionally, Capture/Compare Module 4 offers watchdog timer (WDT) capabilities. Following a system reset, Module 4 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 1.14. PCA Block Diagram 32 Rev. 1.8 CEX4 Port I/O CEX3 CEX2 CEX1 CEX0 ECI Crossbar Capture/Compare Module 4 / WDT C8051F310/1/2/3/4/5/6/7 1.7. 12-Bit Analog to Digital Converter The C8051F310/1/2/3/6 devices include an on-chip 12-bit SAR ADC with a 25-channel differential input multiplexer. With a maximum throughput of 200 ksps, the ADC offers true 12-bit accuracy with an INL of ±1LSB. The ADC system includes a configurable analog multiplexer that selects both positive and negative ADC inputs. Ports1-3 are available as an ADC inputs; additionally, the on-chip Temperature Sensor output and the power supply voltage (VDD) are available as ADC inputs. User firmware may shut down the ADC to save power. Conversions can be started in six ways: a software command, an overflow of Timer 0, 1, 2, or 3, or an external convert start signal. This flexibility allows the start of conversion to be triggered by software events, a periodic signal (timer overflows), or external HW signals. Conversion completions are indicated by a status bit and an interrupt (if enabled). The resulting 12-bit data word is latched into the ADC data SFRs upon completion of a conversion. Window compare registers for the ADC data can be configured to interrupt the controller when ADC data is either within or outside of a specified range. The ADC can monitor a key voltage continuously in background mode, but not interrupt the controller unless the converted data is within/outside the specified range. Analog Multiplexer P1.0 P1.6, P1.7 available on C8051F310/1/2/3/4/5 P2.6, P2.7 available on C8051F310/1/2/3/4/5 P3.1-3.4 available on C8051F310/2 Configuration, Control, and Data Registers P1.7 P2.0 23-to-1 AMUX Start Conversion P2.7 P3.0 P3.4 000 AD0BUSY (W) 001 Timer 0 Overflow 010 Timer 2 Overflow 011 Timer 1 Overflow 100 CNVSTR Input 101 Timer 3 Overflow VDD Temp Sensor (+) (-) P1.0 P1.6, P1.7 available on C8051F310/1/2/3/4/5 P2.6, P2.7 available on C8051F310/1/2/3/4/5 P3.1-3.4 available on C8051F310/2 10-Bit SAR ADC P1.7 P2.0 End of Conversion Interrupt 23-to-1 AMUX 16 ADC Data Registers Window Compare Logic Window Compare Interrupt P2.7 P3.0 P3.4 VREF GND Figure 1.15. 12-Bit ADC Block Diagram Rev. 1.8 33 C8051F310/1/2/3/4/5/6/7 1.8. Comparators C8051F31x devices include two on-chip voltage comparators that are enabled/disabled and configured via user software. Port I/O pins may be configured as comparator inputs via a selection mux. Two comparator outputs may be routed to a Port pin if desired: a latched output and/or an unlatched (asynchronous) output. Comparator response time is programmable, allowing the user to select between high-speed and lowpower modes. Positive and negative hysteresis are also configurable. Comparator interrupts may be generated on rising, falling, or both edges. When in IDLE mode, these interrupts may be used as a “wake-up” source. Comparator0 may also be configured as a reset source. Figure 1.16 shows he Comparator0 block diagram. CP0EN CPT0CN CPT0MX CP0OUT CMX0N1 CMX0N0 CP0RIF VDD CP0FIF CP0HYP1 CP0HYP0 CP0 Interrupt CP0HYN1 CP0HYN0 CMX0P1 CMX0P0 CP0 Rising-edge P1.0 CP0 Falling-edge P1.4 P2.0 CP0 + Interrupt Logic P2.4 CP0 + D - CLR Q Q D SET CLR Q Q Crossbar P1.1 P1.5 SET (SYNCHRONIZER) GND CP0 - P2.1 CP0A Reset Decision Tree CPT0MD P2.5 CP0RIE CP0FIE CP0MD1 CP0MD0 Figure 1.16. Comparator0 Block Diagram 34 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 2. Absolute Maximum Ratings Table 2.1. Absolute Maximum Ratings* Parameter Conditions Min Typ Max Units Ambient temperature under bias –55 — 125 °C Storage Temperature –65 — 150 °C Voltage on any Port I/O Pin or RST with respect to GND –0.3 — 5.8 V Voltage on VDD with respect to GND –0.3 — 4.2 V Maximum Total current through VDD and GND — — 500 mA Maximum output current sunk by RST or any Port pin — — 100 mA *Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Rev. 1.8 35 C8051F310/1/2/3/4/5/6/7 3. Global DC Electrical Characteristics Table 3.1. Global DC Electrical Characteristics –40°C to +85°C, 25 MHz System Clock unless otherwise specified. Parameter Conditions Typ Max Units 3.0 3.6 V — 1.5 — V –40 — +85 °C SYSCLK (system clock frequency) 02 — 25 MHz Tsysl (SYSCLK low time) 18 — — ns Tsysh (SYSCLK high time) 18 — — ns Digital Supply Voltage Min VRST Digital Supply RAM Data Retention Voltage Specified Operating Temperature Range 1 Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash) IDD (Note 3) IDD Supply Sensitivity (Note 3, Note 4) VDD = 3.0 V, F = 25 MHz — 7.8 8.6 mA VDD = 3.0 V, F = 1 MHz — 0.38 — mA VDD = 3.0 V, F = 80 kHz — 31 — µA VDD = 3.6 V, F = 25 MHz — 10.7 12.1 mA F = 25 MHz — 67 — %/V F = 1 MHz — 62 — %/V IDD Frequency Sensitivity (Note 3, VDD = 3.0 V, F < 15 MHz, T = 25 ºC Note 5) VDD = 3.0 V, F > 15 MHz, T = 25 ºC — 0.39 — mA/MHz — 0.21 — mA/MHz VDD = 3.6 V, F < 15 MHz, T = 25 ºC — 0.55 — mA/MHz VDD = 3.6 V, F > 15 MHz, T = 25 ºC — 0.27 — mA/MHz Notes: 1. 2. 3. 4. Given in Table 9.1 on page 110. SYSCLK must be at least 32 kHz to enable debugging. Based on device characterization data, not production tested. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated using the IDD Supply Sensitivity. For example, if the VDD is 3.3 V instead of 3.0 V at 25 MHz: IDD = 7.8 mA typical at 3.0 V and f = 25 MHz. From this, IDD = 7.8 mA + 0.67 x (3.3 V – 3.0 V) = 8 mA at 3.3 V and f = 25 MHz. 5. IDD can be estimated for frequencies < 15 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate IDD for > 15 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:  VDD = 3.0 V; F = 20 MHz, IDD = 7.8 mA – (25 MHz – 20 MHz) x 0.21 mA/MHz = 6.75 mA. 6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:  VDD = 3.0 V; F = 5 MHz, Idle IDD = 4.8 mA – (25 MHz – 5 MHz) x 0.15 mA/MHz = 1.8 mA. 36 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Table 3.1. Global DC Electrical Characteristics (Continued) –40°C to +85°C, 25 MHz System Clock unless otherwise specified. Parameter Conditions Min Typ Max Units Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash) IDD (Note 3) IDD Supply Sensitivity (Note 3, Note 4) IDD Frequency Sensitivity (Note 3, Note 6) Digital Supply Current  (Stop Mode, shutdown) VDD = 3.0 V, F = 25 MHz — 3.8 4.3 mA VDD = 3.0 V, F = 1 MHz — 0.20 — mA VDD = 3.0 V, F = 80 kHz — 16 — µA VDD = 3.6 V, F = 25 MHz — 4.8 5.3 mA F = 25 MHz — 44 — %/V F = 1 MHz — 56 — %/V VDD = 3.0 V, F < 1 MHz, T = 25 °C — 0.21 — mA/MHz VDD = 3.0 V, F > 1 MHz, T = 25 °C — 0.15 — mA/MHz VDD = 3.6 V, F < 1 MHz, T = 25 °C — 0.28 — mA/MHz VDD = 3.6 V, F > 1 MHz, T = 25 °C — 0.19 — mA/MHz Oscillator not running, VDD Monitor Disabled — < 0.1 — µA Notes: 1. 2. 3. 4. Given in Table 9.1 on page 110. SYSCLK must be at least 32 kHz to enable debugging. Based on device characterization data, not production tested. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated using the IDD Supply Sensitivity. For example, if the VDD is 3.3 V instead of 3.0 V at 25 MHz: IDD = 7.8 mA typical at 3.0 V and f = 25 MHz. From this, IDD = 7.8 mA + 0.67 x (3.3 V – 3.0 V) = 8 mA at 3.3 V and f = 25 MHz. 5. IDD can be estimated for frequencies < 15 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate IDD for > 15 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:  VDD = 3.0 V; F = 20 MHz, IDD = 7.8 mA – (25 MHz – 20 MHz) x 0.21 mA/MHz = 6.75 mA. 6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1 MHz, the estimate should be the current at 25 MHz minus the difference in current indicated by the frequency sensitivity number. For example:  VDD = 3.0 V; F = 5 MHz, Idle IDD = 4.8 mA – (25 MHz – 5 MHz) x 0.15 mA/MHz = 1.8 mA. Rev. 1.8 37 C8051F310/1/2/3/4/5/6/7 Other electrical characteristics tables are found in the data sheet section corresponding to the associated peripherals. For more information on electrical characteristics for a specific peripheral, refer to the page indicated in Table 3.2. Table 3.2. Electrical Characteristics Quick Reference Peripheral Electrical Characteristics Page No. ADC0 Electrical Characteristics 65 External Voltage Reference Circuit Electrical Characteristics 68 Comparator Electrical Characteristics 78 Reset Electrical Characteristics 110 Flash Electrical Characteristics 112 Internal Oscillator Electrical Characteristics 123 Port I/O DC Electrical Characteristics 143 38 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 4. Pinout and Package Definitions Table 4.1. Pin Definitions for the C8051F31x Name Pin Numbers ‘F310/2/4 ‘F311/3/5 ‘F316/7 Type Description VDD 4 4 4 Power Supply Voltage. GND 3 3 3 Ground. RST/ D I/O Device Reset. Open-drain output of internal POR. An external source can initiate a system reset by driving this pin low for at least 10 µs. C2CK D I/O Clock signal for the C2 Debug Interface. P3.0/ D I/O Port 3.0. See Section 13 for a complete description. D I/O Bi-directional data signal for the C2 Debug Interface. D I/O Port 0.0. See Section 13 for a complete description. A In External VREF input. (‘F310/1/2/3 only) D I/O Port 0.1. See Section 13 for a complete description. D I/O Port 0.2. See Section 13 for a complete description. XTAL1 A In External Clock Input. This pin is the external oscillator return for a crystal or resonator. P0.3/ D I/O Port 0.3. See Section 13 for a complete description. 5 6 5 6 5 6 C2D P0.0/ 2 2 2 VREF P0.1 1 1 1 P0.2/ 32 28 24 External Clock Output. For an external crystal or resoA Out or nator, this pin is the excitation driver. This pin is the D In external clock input for CMOS, capacitor, or RC oscillator configurations. 31 27 23 P0.4 30 26 22 D I/O Port 0.4. See Section 13 for a complete description. P0.5 29 25 21 D I/O Port 0.5. See Section 13 for a complete description. 28 24 20 P0.7 27 23 19 P1.0 26 22 18 D I/O or Port 1.0. See Section 13 for a complete description. A In P1.1 25 21 17 D I/O or Port 1.1. See Section 13 for a complete description. A In P1.2 24 20 16 D I/O or Port 1.2. See Section 13 for a complete description. A In P1.3 23 19 15 D I/O or Port 1.3. See Section 13 for a complete description. A In P1.4 22 18 14 D I/O or Port 1.4. See Section 13 for a complete description. A In XTAL2 P0.6/ Port 0.6. See Section 13 for a complete description. CNVSTR ADC0 External Convert Start Input. (‘F310/1/2/3 only) D I/O Port 0.7. See Section 13 for a complete description. Rev. 1.8 39 C8051F310/1/2/3/4/5/6/7 Table 4.1. Pin Definitions for the C8051F31x (Continued) Name 40 Pin Numbers ‘F310/2/4 ‘F311/3/5 ‘F316/7 13 Type Description D I/O or Port 1.5. See Section 13 for a complete description. A In P1.5 21 17 P1.6 20 16 D I/O or Port 1.6. See Section 13 for a complete description. A In P1.7 19 15 D I/O or Port 1.7. See Section 13 for a complete description. A In P2.0 18 14 12 D I/O or Port 2.0. See Section 13 for a complete description. A In P2.1 17 13 11 D I/O or Port 2.1. See Section 13 for a complete description. A In P2.2 16 12 10 D I/O or Port 2.2. See Section 13 for a complete description. A In P2.3 15 11 9 D I/O or Port 2.3. See Section 13 for a complete description. A In P2.4 14 10 8 D I/O or Port 2.4. See Section 13 for a complete description. A In P2.5 13 9 7 D I/O or Port 2.5. See Section 13 for a complete description. A In P2.6 12 8 D I/O or Port 2.6. See Section 13 for a complete description. A In P2.7 11 7 D I/O or Port 2.7. See Section 13 for a complete description. A In P3.1 7 D I/O or Port 3.1. See Section 13 for a complete description. A In P3.2 8 D I/O or Port 3.2. See Section 13 for a complete description. A In P3.3 9 D I/O or Port 3.3. See Section 13 for a complete description. A In P3.4 10 D I/O or Port 3.4. See Section 13 for a complete description. A In Rev. 1.8 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 P1.0 P1.1 32 31 30 29 28 27 26 25 C8051F310/1/2/3/4/5/6/7 P0.1 1 24 P1.2 P0.0 2 23 P1.3 GND 3 22 P1.4 VDD 4 21 P1.5 /RST/C2CK 5 20 P1.6 P3.0/C2D 6 19 P1.7 P3.1 7 18 P2.0 P3.2 8 17 P2.1 13 14 15 16 P2.5 P2.4 P2.3 P2.2 11 P2.7 12 10 P3.4 P2.6 9 P3.3 C8051F310/2/4 Top View Figure 4.1. LQFP-32 Pinout Diagram (Top View) Rev. 1.8 41 C8051F310/1/2/3/4/5/6/7 Table 4.2. LQFP-32 Package Dimensions D D1 E1 E 32 PIN 1 IDENTIFIER A A1 A2 b D D1 e E E1 L 1 A2 A L b A1 e Figure 4.2. LQFP-32 Package Diagram 42 Rev. 1.8 MIN 0.05 1.35 0.30 0.45 MM TYP 1.40 0.37 9.00 7.00 0.80 9.00 7.00 0.60 MAX 1.60 0.15 1.45 0.45 0.75 C8051F310/1/2/3/4/5/6/7 Figure 4.3. Typical LQFP-32 Landing Diagram Table 4.3. LQFP-32 Landing Pattern Dimensions Dimension Min Max C1 C2 E X1 Y1 8.40 8.40 8.50 8.50 0.80 BSC. 0.40 1.25 0.50 1.35 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60?m minimum, all the way around the pad. 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all pads. 7. A No-Clean, Type-3 solder paste is recommended. 8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C specification for Small Body Components. Rev. 1.8 43 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 P1.0 27 26 25 24 23 22 GND 28 C8051F310/1/2/3/4/5/6/7 P0.1 1 21 P1.1 P0.0 2 20 P1.2 GND 3 19 P1.3 VDD 4 18 P1.4 /RST/C2CK 5 17 P1.5 P3.0/C2D 6 16 P1.6 15 P1.7 C8051F311/3/5 Top View GND 8 9 10 11 12 13 14 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 7 P2.6 P2.7 Figure 4.4. QFN-28 Pinout Diagram (Top View) 44 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Figure 4.5. QFN-28 Package Drawing Table 4.4. QFN-28 Package Dimensions MM MM Dimension Min Nom Max Dimension Min Nom Max A A1 A3 b D D2 e E E2 0.80 0.00 0.90 0.02 0.25 REF 0.23 5.00 BSC. 3.15 0.50 BSC. 5.00 BSC. 3.15 1.00 0.05 L L1 aaa bbb ddd eee Z Y 0.35 0.00 0.55 — 0.15 0.10 0.05 0.08 0.44 0.18 0.65 0.15 0.18 2.90 2.90 0.30 3.35 3.35 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC outline MO-220, variation VHHD except for custom features D2, E2, L, Z, and Y 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. 1.8 45 C8051F310/1/2/3/4/5/6/7 Figure 4.6. Typical QFN-28 Landing Diagram Table 4.5. QFN-28 Landing Pattern Dimensions Dimension C1 C2 E X1 X2 Y1 Y2 Min Max 4.80 4.80 0.50 0.20 3.20 0.85 3.20 0.30 3.30 0.95 3.30 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification. 3. This Land Pattern Design is based on the IPC-7351 guidelines. 4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60?m minimum, all the way around the pad. 5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 6. The stencil thickness should be 0.125mm (5 mils). 7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins. 8. A 3x3 array of 0.90mm openings on a 1.1mm pitch should be used for the center pad to assure the proper paste volume. 9. A No-Clean, Type-3 solder paste is recommended. 10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 46 Rev. 1.8 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 24 23 22 21 20 19 C8051F310/1/2/3/4/5/6/7 P0.1 1 18 P1.0 P0.0 2 17 P1.1 GND 3 16 P1.2 VDD 4 15 P1.3 /RST / C2CK 5 14 P1.4 P3.0 / C2D 6 13 P1.5 C8051F316/7 Top View 7 8 9 10 11 12 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 GND Figure 4.7. QFN-24 Pinout Diagram (Top View) Rev. 1.8 47 C8051F310/1/2/3/4/5/6/7 Figure 4.8. QFN-24 Package Drawing Table 4.6. QFN-24 Package Dimensions MM MM Dimension Min Nom Max Dimension Min Nom Max A A1 b D D2 e E E2 0.70 0.00 0.18 0.75 0.02 0.25 4.00 BSC. 2.70 0.50 BSC. 4.00 BSC. 2.70 0.80 0.05 0.30 L L1 aaa bbb ddd eee Z Y 0.30 0.00 — — — — 0.40 — — — — — 0.24 0.18 0.50 0.15 0.15 0.10 0.05 0.08 2.55 2.55 2.80 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. 48 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Figure 4.9. Typical QFN-24 Landing Diagram Table 4.7. QFN-24 Landing Pattern Dimensions Dimension Min Max C1 C2 E X1 X2 Y1 Y2 3.90 3.90 4.00 4.00 0.50 BSC. 0.20 2.70 0.65 2.70 0.30 2.80 0.75 2.80 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This land pattern design is based on the IPC-7351 guidelines. 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60?m minimum, all the way around the pad. 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 7. A 2x2 array of 1.10mm x 1.10mm openings on 1.30mm pitch should be used for the center ground pad. 8. A No-Clean, Type-3 solder paste is recommended. 9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.8 49 C8051F310/1/2/3/4/5/6/7 50 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 5. 12-Bit ADC (ADC0, C8051F310/1/2/3/6 only) The ADC0 subsystem for the C8051F310/1/2/3/6 consists of two analog multiplexers (referred to collectively as AMUX0) with 25 total input selections, and a 200 ksps, 12-bit successive-approximation-register ADC with integrated track-and-hold and programmable window detector. The AMUX0, data conversion modes, and window detector are all configurable under software control via the Special Function Registers shown in Figure 5.1. ADC0 operates in both Single-ended and Differential modes, and may be configured to measure P1.0–P3.4, the Temperature Sensor output, or VDD with respect to P1.0–P3.4, VREF, or GND. The ADC0 subsystem is enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0. P1.0 P2.6-2.7 available on C8051F310/1/2/3/4/5 P3.1-3.4 available on C8051F310/2 P3.4 ADC0L 10-Bit SAR (+) ADC0CF AD0BUSY (W) 001 010 Timer 0 Overflow Timer 2 Overflow 011 100 Timer 1 Overflow CNVSTR Input 101 Timer 3 Overflow REF SYSCLK AD0SC0 AD0LJST AD0SC1 AD0SC2 AD0SC3 AMX0N0 AMX0N1 P3.4 AMX0N2 AMX0N4 P2.7 P3.0 AMX0N AMX0N3 23-to-1 AMUX AD0SC4 P1.7 P2.0 000 ADC0H ADC (-) P1.0 P3.1-3.4 available on C8051F310/2 AD0CM0 Start Conversion Temp Sensor P2.6-2.7 available on C8051F310/1/2/3/4/5 AD0CM1 VDD P2.7 P3.0 VDD P1.6-1.7 available on C8051F310/1/2/3/4/5 AD0CM2 AD0WINT AD0INT AD0BUSY AD0EN 23-to-1 AMUX AD0TM AMX0P0 ADC0CN AMX0P1 AMX0P2 P1.7 P2.0 AMX0P3 AMX0P4 AMX0P P1.6-1.7 available on C8051F310/1/2/3/4/5 AD0WINT 32 ADC0LTH ADC0LTL Window Compare Logic ADC0GTH ADC0GTL VREF GND Figure 5.1. ADC0 Functional Block Diagram 5.1. Analog Multiplexer AMUX0 selects the positive and negative inputs to the ADC. Any of the following may be selected as the positive input: P1.0-P3.4, the on-chip temperature sensor, or the positive power supply (VDD). Any of the following may be selected as the negative input: P1.0-P3.4, VREF, or GND. When GND is selected as the negative input, ADC0 operates in Single-ended Mode; all other times, ADC0 operates in Differential Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in SFR Definition 5.1 and SFR Definition 5.2. The conversion code format differs between Single-ended and Differential modes. The registers ADC0H and ADC0L contain the high and low bytes of the output conversion code from the ADC at the completion of each conversion. Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit (ADC0CN.0). When in Single-ended Mode, conversion codes are represented as 12-bit unsigned integers. Rev. 1.8 51 C8051F310/1/2/3/4/5/6/7 Inputs are measured from ‘0’ to VREF * 1023/1024. Example codes are shown below for both right-justified and left-justified data. Unused bits in the ADC0H and ADC0L registers are set to ‘0’. Input Voltage Right-Justified ADC0H:ADC0L (AD0LJST = 0) 0x03FF 0x0200 0x0100 0x0000 VREF x 1023/1024 VREF x 512/1024 VREF x 256/1024 0 Left-Justified ADC0H:ADC0L (AD0LJST = 1) 0xFFC0 0x8000 0x4000 0x0000 When in Differential Mode, conversion codes are represented as 12-bit signed 2’s complement numbers. Inputs are measured from -VREF to VREF * 511/512. Example codes are shown below for both right-justified and left-justified data. For right-justified data, the unused MSBs of ADC0H are a sign-extension of the data word. For left-justified data, the unused LSBs in the ADC0L register are set to ‘0’. Input Voltage Right-Justified ADC0H:ADC0L (AD0LJST = 0) 0x01FF 0x0100 0x0000 0xFF00 0xFE00 VREF x 511/512 VREF x 256/512 0 –VREF x 256/512 –VREF Left-Justified ADC0H:ADC0L (AD0LJST = 1) 0x7FC0 0x4000 0x0000 0xC000 0x8000 Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be configured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog input, set to ‘0’ the corresponding bit in register PnMDIN (for n = 0,1,2,3). To force the Crossbar to skip a Port pin, set to ‘1’ the corresponding bit in register PnSKIP (for n = 0,1,2). See Section “13. Port Input/ Output” on page 129 for more Port I/O configuration details. 5.2. Temperature Sensor The typical temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the positive ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P. (mV) 1200 1100 1000 900 VTEMP = 3.35*(TEMPC) + 897 mV 800 700 -50 0 50 100 (Celsius) Figure 5.2. Typical Temperature Sensor Transfer Function 52 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature measurements (see Table 5.1 for linearity specifications). For absolute temperature measurements, gain and/ or offset calibration is recommended. Typically a 1-point calibration includes the following steps: Step 1. Control/measure the ambient temperature (this temperature must be known). Step 2. Power the device, and delay for a few seconds to allow for self-heating. Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input and GND selected as the negative input. Step 4. Calculate the offset and/or gain characteristics, and store these values in non-volatile memory for use with subsequent temperature sensor measurements. Error (degrees C) Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Note that parameters which affect ADC measurement, in particular the voltage reference value, will also affect temperature measurement. 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 0.00 -40.00 -20.00 40.00 0.00 60.00 20.00 0.00 80.00 -1.00 -1.00 -2.00 -2.00 -3.00 -3.00 -4.00 -4.00 -5.00 -5.00 Temperature (degrees C) Figure 5.3. Temperature Sensor Error with 1-Point Calibration Rev. 1.8 53 C8051F310/1/2/3/4/5/6/7 5.3. Modes of Operation ADC0 has a maximum conversion speed of 200 ksps. The ADC0 conversion clock is a divided version of the system clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by (AD0SC + 1) for 0  AD0SC 31). 5.3.1. Starting a Conversion A conversion can be initiated in one of five ways, depending on the programmed states of the ADC0 Start of Conversion Mode bits (AD0CM2-0) in register ADC0CN. Conversions may be initiated by one of the following: 1. 2. 3. 4. 5. 6. Writing a ‘1’ to the AD0BUSY bit of register ADC0CN A Timer 0 overflow (i.e., timed continuous conversions) A Timer 2 overflow A Timer 1 overflow A rising edge on the CNVSTR input signal (pin P0.6) A Timer 3 overflow Writing a ‘1’ to AD0BUSY provides software control of ADC0 whereby conversions are performed "ondemand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit mode. See Section “17. Timers” on page 187 for timer configuration. Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port pin P0.6. When the CNVSTR input is used as the ADC0 conversion source, Port pin P0.6 should be skipped by the Digital Crossbar. To configure the Crossbar to skip P0.6, set to ‘1’ Bit6 in register P0SKIP. See Section “13. Port Input/Output” on page 129 for details on Port I/O configuration. 54 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 5.3.2. Tracking Modes According to Table 5.1, each ADC0 conversion must be preceded by a minimum tracking time for the converted result to be accurate. The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0 input is continuously tracked, except when a conversion is in progress. When the AD0TM bit is logic 1, ADC0 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR is low; conversion begins on the rising edge of CNVSTR (see Figure 5.4). Tracking can also be disabled (shutdown) when the device is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX settings are frequently changed, due to the settling time requirements described in Section “5.3.3. Settling Time Requirements” on page 56. A. ADC0 Timing for External Trigger Source CNVSTR (AD0CM[2:0]=100) 1 2 3 4 5 6 7 8 9 10 11 SAR Clocks AD0TM=1 AD0TM=0 Write '1' to AD0BUSY, Timer 0, Timer 2, Timer 1, Timer 3 Overflow (AD0CM[2:0]=000, 001,010 011, 101) Low Power or Convert Track Track or Convert Convert Low Power Mode Convert Track B. ADC0 Timing for Internal Trigger Source 1 2 3 4 5 6 7 8 9 10 11 12 13 14 SAR Clocks AD0TM=1 Low Power or Convert Track 1 2 3 Convert 4 5 6 7 8 9 Low Power Mode 10 11 SAR Clocks AD0TM=0 Track or Convert Convert Track Figure 5.4. 12-Bit ADC Track and Conversion Example Timing Rev. 1.8 55 C8051F310/1/2/3/4/5/6/7 5.3.3. Settling Time Requirements When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum tracking time is required before an accurate conversion can be performed. This tracking time is determined by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. In low-power tracking mode, three SAR clocks are used for tracking at the start of every conversion. For most applications, these three SAR clocks will meet the minimum tracking time requirements. Figure 5.5 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature Sensor output or VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum settling time requirements. Equation 5.1. ADC0 Settling Time Requirements n 2 t = ln  -------  R TOTAL C SAMPLE SA Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds RTOTAL is the sum of the AMUX0 resistance and any external source resistance. n is the ADC resolution in bits (12). Differential Mode Single-Ended Mode MUX Select MUX Select Px.x Px.x RMUX = 5k RMUX = 5k CSAMPLE = 5pF CSAMPLE = 5pF RCInput= RMUX * CSAMPLE RCInput= RMUX * CSAMPLE CSAMPLE = 5pF Px.x RMUX = 5k MUX Select Figure 5.5. ADC0 Equivalent Input Circuits 56 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select R R R R/W R/W R/W R/W - - - AMX0P4 AMX0P3 AMX0P2 AMX0P1 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 R/W Reset Value AMX0P0 00000000 Bit0 SFR Address: 0xBB Bits7–5: UNUSED. Read = 000b; Write = don’t care. Bits4–0: AMX0P4–0: AMUX0 Positive Input Selection AMX0P4–0 00000 00001 00010 00011 00100 00101 00110 ADC0 Positive Input P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 00111 P1.7(1) P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 01000 01001 01010 01011 01100 01101 01110 01111 P1.6(1) P2.6(1) 10000 P2.7(1) P3.0 10001(2) P3.1(2) 10010(2) P3.2(2) 10011(2) P3.3(2) 10100(2) 10101–11101 11110 11111 P3.4(2) RESERVED Temp Sensor VDD Notes: 1. Only applies to C8051F310/1/2/3/4/5; selection RESERVED on C8051F316/7 devices. 2. Only applies to C8051F310/2; selection RESERVED on C8051F311/3/6/7 devices. Rev. 1.8 57 C8051F310/1/2/3/4/5/6/7 SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select R R R R/W R/W R/W R/W - - - AMX0N4 AMX0N3 AMX0N2 AMX0N1 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 R/W Reset Value AMX0N0 00000000 Bit0 SFR Address: 0xBA Bits7–5: UNUSED. Read = 000b; Write = don’t care. Bits4–0: AMX0N4–0: AMUX0 Negative Input Selection. Note that when GND is selected as the Negative Input, ADC0 operates in Single-ended mode. For all other Negative Input selections, ADC0 operates in Differential mode. AMX0N4–0 00000 00001 00010 00011 00100 00101 00110 ADC0 Negative Input P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 00111 P1.7(1) P2.0 P2.1 P2.2 P2.3 P2.4 P2.5 01000 01001 01010 01011 01100 01101 01110 01111 P1.6(1) P2.6(1) 10000 P2.7(1) P3.0 10001(2) P3.1(2) 10010(2) P3.2(2) 10011(2) P3.3(2) 10100(2) 10101–11101 11110 11111 P3.4(2) RESERVED VREF GND (ADC in Single-Ended Mode) Notes: 1. Only applies to C8051F310/1/2/3/4/5; selection RESERVED on C8051F316/7 devices. 2. Only applies to C8051F310/2; selection RESERVED on C8051F311/3/6/7 devices. 58 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 5.3. ADC0CF: ADC0 Configuration R/W R/W R/W R/W AD0SC4 AD0SC3 AD0SC2 AD0SC1 Bit7 Bit6 Bit5 Bit4 R/W R/W AD0SC0 AD0LJST Bit3 Bit2 R/W R/W Reset Value - - 11111000 Bit1 Bit0 SFR Address: 0xBC Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in bits AD0SC4–0. SAR Conversion clock requirements are given in Table 5.1. SYSCLK AD0SC = ---------------------- – 1 CLK SAR Bit2: AD0LJST: ADC0 Left Justify Select. 0: Data in ADC0H:ADC0L registers are right-justified. 1: Data in ADC0H:ADC0L registers are left-justified. Bits1–0: UNUSED. Read = 00b; Write = don’t care. SFR Definition 5.4. ADC0H: ADC0 Data Word MSB R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xBE Bits7–0: ADC0 Data Word High-Order Bits. For AD0LJST = 0: Bits 7–2 are the sign extension of Bit1. Bits 1–0 are the upper 2 bits of the 12-bit ADC0 Data Word. For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 12-bit ADC0 Data Word. SFR Definition 5.5. ADC0L: ADC0 Data Word LSB R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xBD Bits7–0: ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 12-bit Data Word. For AD0LJST = 1: Bits 7–6 are the lower 2 bits of the 12-bit Data Word. Bits 5–0 will always read ‘0’. Rev. 1.8 59 C8051F310/1/2/3/4/5/6/7 SFR Definition 5.6. ADC0CN: ADC0 Control R/W R/W AD0EN AD0TM Bit7 Bit6 R/W R/W R/W R/W R/W R/W AD0INT AD0BUSY AD0WINT AD0CM2 AD0CM1 Bit5 Bit4 Bit3 Bit2 Bit1 AD0CM0 00000000 Bit0 (bit addressable) Bit7: Reset Value SFR Address: 0xE8 AD0EN: ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. Bit6: AD0TM: ADC0 Track Mode Bit. 0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a conversion is in progress. 1: Low-power Track Mode: Tracking Defined by AD0CM2-0 bits (see below). Bit5: AD0INT: ADC0 Conversion Complete Interrupt Flag. 0: ADC0 has not completed a data conversion since the last time AD0INT was cleared. 1: ADC0 has completed a data conversion. Bit4: AD0BUSY: ADC0 Busy Bit. Read: 0: ADC0 conversion is complete or a conversion is not currently in progress. AD0INT is set to logic 1 on the falling edge of AD0BUSY. 1: ADC0 conversion is in progress. Write: 0: No Effect. 1: Initiates ADC0 Conversion if AD0CM2-0 = 000b Bit3: AD0WINT: ADC0 Window Compare Interrupt Flag. 0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC0 Window Comparison Data match has occurred. Bits2–0: AD0CM2–0: ADC0 Start of Conversion Mode Select. When AD0TM = 0: 000: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY. 001: ADC0 conversion initiated on overflow of Timer 0. 010: ADC0 conversion initiated on overflow of Timer 2. 011: ADC0 conversion initiated on overflow of Timer 1. 100: ADC0 conversion initiated on rising edge of external CNVSTR. 101: ADC0 conversion initiated on overflow of Timer 3. 11x: Reserved. When AD0TM = 1: 000: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR clocks, followed by conversion. 001: Tracking initiated on overflow of Timer 0 and lasts 3 SAR clocks, followed by conversion. 010: Tracking initiated on overflow of Timer 2 and lasts 3 SAR clocks, followed by conversion. 011: Tracking initiated on overflow of Timer 1 and lasts 3 SAR clocks, followed by conversion. 100: ADC0 tracks only when CNVSTR input is logic low; conversion starts on rising CNVSTR edge. 101: Tracking initiated on overflow of Timer 3 and lasts 3 SAR clocks, followed by conversion. 11x: Reserved. 60 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 5.4. Programmable Window Detector The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-programmed limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL) registers hold the comparison values. The window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0 Less-Than and ADC0 Greater-Than registers. SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xC4 Bits7–0: High byte of ADC0 Greater-Than Data Word. SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xC3 Bits7–0: Low byte of ADC0 Greater-Than Data Word. Rev. 1.8 61 C8051F310/1/2/3/4/5/6/7 SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xC6 Bits7–0: High byte of ADC0 Less-Than Data Word. SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xC5 Bits7–0: Low byte of ADC0 Less-Than Data Word. 62 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 5.4.1. Window Detector In Single-Ended Mode Figure 5.6 shows two example window comparisons for right-justified, single-ended data, with ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). In single-ended mode, the input voltage can range from ‘0’ to VREF x (1023/1024) with respect to GND, and is represented by a 10-bit unsigned integer value. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 5.7 shows an example using left-justified data with the same comparison values. ADC0H:ADC0L ADC0H:ADC0L Input Voltage (Px.x - GND) VREF x (1023/1024) Input Voltage (Px.x - GND) 0x03FF VREF x (1023/1024) 0x03FF AD0WINT not affected AD0WINT=1 0x0081 VREF x (128/1024) 0x0080 0x0081 ADC0LTH:ADC0LTL VREF x (128/1024) 0x007F 0x0080 0x007F AD0WINT=1 VREF x (64/1024) 0x0041 0x0040 ADC0GTH:ADC0GTL VREF x (64/1024) 0x003F 0x0041 0x0040 ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL 0x003F AD0WINT=1 AD0WINT not affected 0 0x0000 0 0x0000 Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data ADC0H:ADC0L ADC0H:ADC0L Input Voltage (Px.x - GND) VREF x (1023/1024) Input Voltage (Px.x - GND) 0xFFC0 VREF x (1023/1024) 0xFFC0 AD0WINT not affected AD0WINT=1 0x2040 VREF x (128/1024) 0x2000 0x2040 ADC0LTH:ADC0LTL VREF x (128/1024) 0x1FC0 0x2000 0x1FC0 AD0WINT=1 0x1040 VREF x (64/1024) 0x1000 0x1040 ADC0GTH:ADC0GTL VREF x (64/1024) 0x0FC0 0x1000 0x0000 AD0WINT not affected ADC0LTH:ADC0LTL 0x0FC0 AD0WINT=1 AD0WINT not affected 0 ADC0GTH:ADC0GTL 0 0x0000 Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data Rev. 1.8 63 C8051F310/1/2/3/4/5/6/7 5.4.2. Window Detector In Differential Mode Figure 5.8 shows two example window comparisons for right-justified, differential data, with ADC0LTH:ADC0LTL = 0x0040 (+64d) and ADC0GTH:ADC0GTH = 0xFFFF (-1d). In differential mode, the measurable voltage between the input pins is between -VREF and VREF*(511/512). Output codes are represented as 12-bit 2’s complement signed integers. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0xFFFF (-1d) < ADC0H:ADC0L < 0x0040 (64d)). In the right example, an AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0xFFFF (-1d) or ADC0H:ADC0L > 0x0040 (+64d)). Figure 5.9 shows an example using left-justified data with the same comparison values. ADC0H:ADC0L ADC0H:ADC0L Input Voltage (Px.x - Px.x) VREF x (511/512) Input Voltage (Px.x - Px.x) 0x01FF VREF x (511/512) 0x01FF AD0WINT not affected AD0WINT=1 0x0041 VREF x (64/512) 0x0040 0x0041 ADC0LTH:ADC0LTL VREF x (64/512) 0x003F 0x0040 0x003F AD0WINT=1 0x0000 VREF x (-1/512) 0xFFFF 0x0000 ADC0GTH:ADC0GTL VREF x (-1/512) 0xFFFE 0xFFFF ADC0GTH:ADC0GTL AD0WINT not affected ADC0LTH:ADC0LTL 0xFFFE AD0WINT=1 AD0WINT not affected -VREF 0x0200 -VREF 0x0200 Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data ADC0H:ADC0L ADC0H:ADC0L Input Voltage (Px.x - Px.x) VREF x (511/512) Input Voltage (Px.x - Px.y) 0x7FC0 VREF x (511/512) 0x7FC0 AD0WINT not affected AD0WINT=1 0x1040 VREF x (64/512) 0x1000 0x1040 ADC0LTH:ADC0LTL VREF x (64/512) 0x0FC0 0x1000 0x0FC0 AD0WINT=1 0x0000 VREF x (-1/512) 0xFFC0 0x0000 ADC0GTH:ADC0GTL VREF x (-1/512) 0xFF80 0xFFC0 AD0WINT not affected ADC0LTH:ADC0LTL 0xFF80 AD0WINT=1 AD0WINT not affected -VREF ADC0GTH:ADC0GTL 0x8000 -VREF 0x8000 Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data 64 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Table 5.1. ADC0 Electrical Characteristics VDD = 3.0 V, VREF = 2.40 V (REFSL=0), –40 to +85 °C unless otherwise specified Parameter Conditions Min Typ Max Units DC Accuracy Resolution 12 Integral Nonlinearity Differential Nonlinearity Guaranteed Monotonic Offset Error Full Scale Error Differential mode Offset Temperature Coefficient bits — ±0.5 ±1 LSB — ±0.5 ±1 LSB –12 1 +12 LSB –15 –5 +5 LSB — 3.6 — ppm/°C Dynamic Performance (10 kHz sine-wave Single-ended input, 0 to 1 dB below Full Scale, 200 ksps) Signal-to-Noise Plus Distortion 53 55.5 — dB — –67 — dB — 78 — dB SAR Conversion Clock — — 3 MHz Conversion Time in SAR Clocks 10 — — clocks Track/Hold Acquisition Time 300 — — ns — — 200 ksps Input Voltage Range 0 — VREF V Input Capacitance — 5 — pF Temperature Sensor — — — Linearity* — ±0.5 — °C Gain* — 3350 ± 10 — µV / °C (Temp = 0 °C) — 897 ± 31 — mV Operating Mode, 200 ksps — 400 900 µA — ±0.3 — mV/V Total Harmonic Distortion Up to the 5th harmonic Spurious-Free Dynamic Range Conversion Rate Throughput Rate Analog Inputs Offset* Power Specifications Power Supply Current  (VDD supplied to ADC0) Power Supply Rejection *Note: Represents one standard deviation from the mean. Includes ADC offset, gain, and linearity variations. Rev. 1.8 65 C8051F310/1/2/3/4/5/6/7 NOTES: 66 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 6. Voltage Reference (C8051F310/1/2/3/6 only) The voltage reference MUX on C8051F310/1/2/3/6 devices is configurable to use an externally connected voltage reference, or the power supply voltage (see Figure 6.1). The REFSL bit in the Reference Control register (REF0CN) selects the reference source. For an external source, REFSL should be set to ‘0’; For VDD as the reference source, REFSL should be set to ‘1’. The BIASE bit enables the internal voltage bias generator, which is used by the ADC, Temperature Sensor, and Internal Oscillator. This bit is forced to logic 1 when any of the aforementioned peripherals is enabled. The bias generator may be enabled manually by writing a ‘1’ to the BIASE bit in register REF0CN; see SFR Definition 6.1 for REF0CN register details. The electrical specifications for the voltage reference circuit are given in Table 6.1. Important Note About the VREF Input: Port pin P0.0 is used as the external VREF input. When using an external voltage reference, P0.0 should be configured as analog input and skipped by the Digital Crossbar. To configure P0.0 as analog input, set to ‘0’ Bit0 in register P0MDIN. To configure the Crossbar to skip P0.0, set to ‘1’ Bit0 in register P0SKIP. Refer to Section “13. Port Input/Output” on page 129 for complete Port I/O configuration details. The temperature sensor connects to the highest order input of the ADC0 positive input multiplexer (see Section “5.1. Analog Multiplexer” on page 51 for details). The TEMPE bit in register REF0CN enables/disables the temperature sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in meaningless data. BIASE REFSL TEMPE REF0CN EN Bias Generator To ADC, Internal Oscillator IOSCEN VDD R1 External Voltage Reference Circuit EN VREF Temp Sensor To Analog Mux 0 Internal VREF (to ADC) GND VDD 1 Figure 6.1. Voltage Reference Functional Block Diagram Rev. 1.8 67 C8051F310/1/2/3/4/5/6/7 SFR Definition 6.1. REF0CN: Reference Control R/W Bit7 R/W Bit6 R/W Bit5 R/W Bit4 R/W R/W R/W REFSL TEMPE BIASE R/W Bit3 Bit2 Bit1 Reset Value 00000000 Bit0 SFR Address: 0xD1 Bits7–4: UNUSED. Read = 0000b; Write = don’t care. Bit3: REFSL: Voltage Reference Select. This bit selects the source for the internal voltage reference. 0: VREF input pin used as voltage reference. 1: VDD used as voltage reference. Bit2: TEMPE: Temperature Sensor Enable Bit. 0: Internal Temperature Sensor off. 1: Internal Temperature Sensor on. Bit1: BIASE: Internal Analog Bias Generator Enable Bit. (Must be ‘1’ if using ADC). 0: Internal Bias Generator off. 1: Internal Bias Generator on. Bit0: UNUSED. Read = 0b. Write = don’t care. Table 6.1. External Voltage Reference Circuit Electrical Characteristics VDD = 3.0 V; –40 to +85 °C unless otherwise specified Parameter Conditions 68 Typ 0 Input Voltage Range Input Current Min Sample Rate = 200 ksps; VREF = 3.0 V Rev. 1.8 12 Max Units VDD V µA C8051F310/1/2/3/4/5/6/7 7. Comparators C8051F31x devices include two on-chip programmable voltage comparators: Comparator0 is shown in Figure 7.1; Comparator1 is shown in Figure 7.2. The two comparators operate identically with the following exceptions: (1) Their input selections differ as shown in Figure 7.1 and Figure 7.2; (2) Comparator0 can be used as a reset source. The Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an asynchronous “raw” output (CP0A, CP1A). The asynchronous CP0A signal is available even when the system clock is not active. This allows the Comparator to operate and generate an output with the device in STOP mode. When assigned to a Port pin, the Comparator output may be configured as open drain or push-pull (see Section “13.2. Port I/O Initialization” on page 133). Comparator0 may also be used as a reset source (see Section “9.5. Comparator0 Reset” on page 108). The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 7.2). The CMX0P1-CMX0P0 bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 7.5). The CMX1P1CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the Comparator1 negative input. Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be configured as analog inputs in their associated Port configuration register, and configured to be skipped by the Crossbar (for details on Port configuration, see Section “13.3. General Purpose Port I/O” on page 135). CPT0CN CMX0N1 CMX0N0 VDD CP0FIF CP0HYP1 CP0HYP0 CP0 Interrupt CP0HYN1 CP0HYN0 CMX0P1 CMX0P0 CP0 Rising-edge P1.0 CP0 Falling-edge P1.4 P2.0 CP0 + Interrupt Logic P2.4 CP0 + D P1.5 SET CLR Q Q D SET CLR Q Q Crossbar P1.1 (SYNCHRONIZER) GND CP0 - P2.1 CP0A Reset Decision Tree P2.5 CPT0MD CPT0MX CP0EN CP0OUT CP0RIF CP0RIE CP0FIE CP0MD1 CP0MD0 Figure 7.1. Comparator0 Functional Block Diagram Rev. 1.8 69 C8051F310/1/2/3/4/5/6/7 The Comparator output can be polled in software, used as an interrupt source, and/or routed to a Port pin. When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system clock; the asynchronous output is available even in STOP mode (with no system clock active). When disabled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state, and its supply current falls to less than 100 nA. See Section “13.1. Priority Crossbar Decoder” on page 131 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be externally driven from –0.25 V to (VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in Table 7.1. CPT1CN CPT1MX The Comparator response time may be configured in software via the CPTnMD registers (see SFR Definition 7.3 and SFR Definition 7.6). Selecting a longer response time reduces the Comparator supply current. See Table 7.1 for complete timing and current consumption specifications. CMX1N1 CMX1N0 CP1EN CP1OUT CP1RIF CP1FIF VDD CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 CP1 Interrupt CMX1P1 CMX1P0 CP1 Rising-edge P1.2 CP1 Falling-edge P1.6 P2.2 CP1 + Interrupt Logic P2.6 CP1 + D - CLR Q Q D SET CLR Q Q Crossbar P1.3 P1.7 SET (SYNCHRONIZER) CP1 - GND P2.3 CP1A Reset Decision Tree CPT1MD P2.7 CP1RIE CP1FIE CP1MD1 CP1MD0 Figure 7.2. Comparator1 Functional Block Diagram 70 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 VIN+ VIN- CP0+ CP0- + CP0 _ OUT CIRCUIT CONFIGURATION Positive Hysteresis Voltage (Programmed with CP0HYP Bits) VIN- INPUTS Negative Hysteresis Voltage (Programmed by CP0HYN Bits) VIN+ VOH OUTPUT VOL Negative Hysteresis Disabled Positive Hysteresis Disabled Maximum Negative Hysteresis Maximum Positive Hysteresis Figure 7.3. Comparator Hysteresis Plot The Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN (for n = 0 or 1). The user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going symmetry of this hysteresis around the threshold voltage. The Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN (shown in SFR Definition 7.1 and SFR Definition 7.4). The amount of negative hysteresis voltage is determined by the settings of the CPnHYN bits. As shown in Table 7.1, settings of 20, 10 or 5 mV of negative hysteresis can be programmed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is determined by the setting the CPnHYP bits. Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “8.3. Interrupt Handler” on page 93). The CPnFIF flag is set to logic 1 upon a Comparator falling-edge interrupt, and the CPnRIF flag is set to logic 1 upon the Comparator rising-edge interrupt. Once set, these bits remain set until cleared by software. The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0. The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to logic 1, and is disabled by clearing this bit to logic 0. Note that false rising edges and falling edges can be detected when the comparator is first powered-on or if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is enabled or its mode bits have been changed. This Power Up Time is specified in Table 7.1 on page 78. Rev. 1.8 71 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.1. CPT0CN: Comparator0 Control R/W R R/W R/W CP0EN CP0OUT CP0RIF CP0FIF Bit7 Bit6 Bit5 Bit4 R/W R/W R/W R/W Reset Value CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x9B Bit7: CP0EN: Comparator0 Enable Bit. 0: Comparator0 Disabled. 1: Comparator0 Enabled. Bit6: CP0OUT: Comparator0 Output State Flag. 0: Voltage on CP0+ < CP0–. 1: Voltage on CP0+ > CP0–. Bit5: CP0RIF: Comparator0 Rising-Edge Interrupt Flag. 0: No Comparator0 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Rising Edge Interrupt has occurred. Bit4: CP0FIF: Comparator0 Falling-Edge Interrupt Flag. 0: No Comparator0 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator0 Falling-Edge Interrupt has occurred. Bits3–2: CP0HYP1-0: Comparator0 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. Bits1–0: CP0HYN1-0: Comparator0 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. 72 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection R/W R/W - - Bit7 Bit6 R/W R/W CMX0N1 CMX0N0 Bit5 Bit4 R/W R/W R/W - - CMX0P1 Bit3 Bit2 Bit1 R/W Reset Value CMX0P0 00000000 Bit0 SFR Address: 0x9F Bits7–6: UNUSED. Read = 00b, Write = don’t care. Bits5–4: CMX0N1–CMX0N0: Comparator0 Negative Input MUX Select. These bits select which Port pin is used as the Comparator0 negative input. CMX0N1 CMX0N0 0 0 0 1 1 0 1 1 Negative Input P1.1 P1.5 P2.1 P2.5 Bits3–2: UNUSED. Read = 00b, Write = don’t care. Bits1–0: CMX0P1–CMX0P0: Comparator0 Positive Input MUX Select. These bits select which Port pin is used as the Comparator0 positive input. CMX0P1 CMX0P0 0 0 0 1 1 0 1 1 Positive Input P1.0 P1.4 P2.0 P2.4 Rev. 1.8 73 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection R/W R/W R/W R/W R/W R/W - - CP0RIE CP0FIE - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 R/W R/W Reset Value CP0MD1 CP0MD0 00000010 Bit1 Bit0 SFR Address: 0x9D Bits7–6: UNUSED. Read = 00b. Write = don’t care. Bit5: CP0RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled. 1: Comparator rising-edge interrupt enabled. Bit4: CP0FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator falling-edge interrupt enabled. Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select These bits select the response time for Comparator0. Mode 0 1 2 3 74 CP0MD1 0 0 1 1 CP0MD0 0 1 0 1 CP0 Response Time (TYP) Fastest Response Time — — Lowest Power Consumption Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.4. CPT1CN: Comparator1 Control R/W R R/W R/W CP1EN CP1OUT CP1RIF CP1FIF Bit7 Bit6 Bit5 Bit4 R/W R/W R/W R/W Reset Value CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x9A Bit7: CP1EN: Comparator1 Enable Bit. 0: Comparator1 Disabled. 1: Comparator1 Enabled. Bit6: CP1OUT: Comparator1 Output State Flag. 0: Voltage on CP1+ < CP1–. 1: Voltage on CP1+ > CP1–. Bit5: CP1RIF: Comparator1 Rising-Edge Interrupt Flag. 0: No Comparator1 Rising Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Rising Edge Interrupt has occurred. Bit4: CP1FIF: Comparator1 Falling-Edge Interrupt Flag. 0: No Comparator1 Falling-Edge Interrupt has occurred since this flag was last cleared. 1: Comparator1 Falling-Edge Interrupt has occurred. Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. Rev. 1.8 75 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection R/W R/W - - Bit7 Bit6 R/W R/W CMX1N1 CMX1N0 Bit5 Bit4 R/W R/W R/W - - CMX1P1 Bit3 Bit2 Bit1 R/W Reset Value CMX1P0 00000000 Bit0 SFR Address: 0x9E Bits7–6: UNUSED. Read = 00b, Write = don’t care. Bits5–4: CMX1N1–CMX1N0: Comparator1 Negative Input MUX Select. These bits select which Port pin is used as the Comparator1 negative input. CMX1N1 CMX1N0 0 0 0 1 1 0 1 1 Negative Input P1.3 P1.7 P2.3 P2.7 Bits3–2: UNUSED. Read = 00b, Write = don’t care. Bits1–0: CMX1P1–CMX1P0: Comparator1 Positive Input MUX Select. These bits select which Port pin is used as the Comparator1 positive input. CMX1P1 CMX1P0 0 0 0 1 1 0 1 1 76 Positive Input P1.2 P1.6 P2.2 P2.6 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection R/W R/W R/W R/W R/W R/W - - CP1RIE CP1FIE - - Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 R/W R/W Reset Value CP1MD1 CP1MD0 00000010 Bit1 Bit0 SFR Address: 0x9C Bits7–6: UNUSED. Read = 00b, Write = don’t care. Bit5: CP1RIE: Comparator Rising-Edge Interrupt Enable. 0: Comparator rising-edge interrupt disabled 1: Comparator rising-edge interrupt enabled. Bit4: CP1FIE: Comparator Falling-Edge Interrupt Enable. 0: Comparator falling-edge interrupt disabled. 1: Comparator falling-edge interrupt enabled. Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select. These bits select the response time for Comparator1. Mode 0 1 2 3 CP1MD1 0 0 1 1 CP1MD0 0 1 0 1 CP1 Response Time (TYP) Fastest Response Time — — Lowest Power Consumption Rev. 1.8 77 C8051F310/1/2/3/4/5/6/7 Table 7.1. Comparator Electrical Characteristics VDD = 3.0 V, –40 to +85 °C unless otherwise noted. All specifications apply to both Comparator0 and Comparator1 unless otherwise noted. Parameter Response Time: Mode 0, Vcm1 = 1.5 V Response Time: Mode 1, Vcm1 = 1.5 V Response Time: Mode 2, Vcm1 = 1.5 V Response Time: Mode 3, Vcm1 = 1.5 V Conditions Min Typ Max Units CP0+ – CP0– = 100 mV — 100 — ns CP0+ – CP0– = –100 mV — 250 — ns CP0+ – CP0– = 100 mV — 175 — ns CP0+ – CP0– = –100 mV — 500 — ns CP0+ – CP0– = 100 mV — 320 — ns CP0+ – CP0– = –100 mV — 1100 — ns CP0+ – CP0– = 100 mV — 1050 — ns CP0+ – CP0– = –100 mV — 5200 — ns — 1.5 4 mV/V Common-Mode Rejection Ratio Positive Hysteresis 1 CP0HYP1-0 = 00 — 0 1 mV Positive Hysteresis 2 CP0HYP1-0 = 01 2 5 7 mV Positive Hysteresis 3 CP0HYP1-0 = 10 5 10 13 mV Positive Hysteresis 4 CP0HYP1-0 = 11 12 20 25 mV Negative Hysteresis 1 CP0HYN1-0 = 00 0 1 mV Negative Hysteresis 2 CP0HYN1-0 = 01 2 5 7 mV Negative Hysteresis 3 CP0HYN1-0 = 10 5 10 13 mV Negative Hysteresis 4 CP0HYN1-0 = 11 12 20 25 mV –0.25 — VDD + 0.25 V Input Capacitance — 7 — pF Input Bias Current — 1 — nA Input Offset Voltage –5 — +5 mV Power Supply Rejection2 — 0.1 1 mV/V Power-up Time — 10 — µs Mode 0 — 7.6 20 µA Mode 1 — 3.2 10 µA Mode 2 — 1.3 5 µA Mode 3 — 0.4 2.5 µA Inverting or Non-Inverting Input Voltage Range Power Supply Supply Current at DC Notes: 1. Vcm is the common-mode voltage on CP0+ and CP0–. 2. Guaranteed by design and/or characterization. 78 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 8. CIP-51 Microcontroller The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The MCU family has a superset of all the peripherals included with a standard 8051. Included are four 16-bit counter/timers (see description in Section 17), an enhanced full-duplex UART (see description in Section 15), an Enhanced SPI (see description in Section 16), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address space (Section 8.2.6), and 29 Port I/O (see description in Section 13). The CIP-51 also includes on-chip debug hardware (see description in Section 20), and interfaces directly with the analog and digital subsystems providing a complete data acquisition or control-system solution in a single integrated circuit. The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as additional custom peripherals and functions to extend its capability (see Figure 8.1 for a block diagram). The CIP-51 includes the following features: - - Fully Compatible with MCS-51 Instruction Set - 25 MIPS Peak Throughput with 25 MHz Clock - 0 to 25 MHz Clock Frequency - 256 Bytes of Internal RAM 29 Port I/O Extended Interrupt Handler Reset Input Power Management Modes On-chip Debug Logic Program and Data Memory Security D8 D8 ACCUMULATOR STACK POINTER TMP1 TMP2 SRAM ADDRESS REGISTER PSW D8 D8 D8 ALU SRAM (256 X 8) D8 DATA BUS B REGISTER D8 D8 D8 DATA BUS DATA BUS SFR_ADDRESS BUFFER D8 DATA POINTER D8 D8 SFR BUS INTERFACE SFR_CONTROL SFR_WRITE_DATA SFR_READ_DATA DATA BUS PC INCREMENTER PROGRAM COUNTER (PC) PRGM. ADDRESS REG. MEM_ADDRESS D8 MEM_CONTROL A16 MEMORY INTERFACE MEM_WRITE_DATA MEM_READ_DATA PIPELINE RESET D8 CONTROL LOGIC SYSTEM_IRQs CLOCK D8 STOP IDLE POWER CONTROL REGISTER INTERRUPT INTERFACE EMULATION_IRQ D8 Figure 8.1. CIP-51 Block Diagram Rev. 1.8 79 C8051F310/1/2/3/4/5/6/7 Performance The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more than eight system clock cycles. With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execution time. Clocks to Execute 1 2 2/3 3 3/4 4 4/5 5 8 Number of Instructions 26 50 5 14 7 3 1 2 1 Programming and Debugging Support In-system programming of the Flash program memory and communication with on-chip debug support logic is accomplished via the Silicon Labs 2-Wire Development Interface (C2). The re-programmable Flash can also be read and changed a single byte at a time by the application software using the MOVC and MOVX instructions. This feature allows program memory to be used for non-volatile data storage as well as updating program code under software control. The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware breakpoints, starting, stopping and single stepping through program execution (including interrupt service routines), examination of the program's call stack, and reading/writing the contents of registers and memory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or other on-chip resources. C2 details can be found in Section “20. C2 Interface” on page 223. The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs provides an integrated development environment (IDE) including an editor, evaluation compiler, assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient in-system device programming and debugging. Third party macro assemblers and C compilers are also available. 8.1. Instruction Set The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51 instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes, addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051. 8.1.1. Instruction and CPU Timing In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based solely on clock cycle timing. All instruction timings are specified in terms of clock cycles. Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 8.1 is the 80 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock cycles for each instruction. 8.1.2. MOVX Instruction and Program Memory The MOVX instruction is typically used to access external data memory (Note: the C8051F31x does not support external data or program memory). In the CIP-51, the MOVX write instruction is used to accesses external RAM and the on-chip program memory space implemented as re-programmable Flash memory. The Flash access feature provides a mechanism for the CIP-51 to update program code and use the program memory space for non-volatile data storage. Refer to Section “10. Flash Memory” on page 111 for further details. Table 8.1. CIP-51 Instruction Set Summary Mnemonic ADD A, Rn ADD A, direct ADD A, @Ri ADD A, #data ADDC A, Rn ADDC A, direct ADDC A, @Ri ADDC A, #data SUBB A, Rn SUBB A, direct SUBB A, @Ri SUBB A, #data INC A INC Rn INC direct INC @Ri DEC A DEC Rn DEC direct DEC @Ri INC DPTR MUL AB DIV AB DA A ANL A, Rn ANL A, direct ANL A, @Ri ANL A, #data ANL direct, A ANL direct, #data ORL A, Rn Description Arithmetic Operations Add register to A Add direct byte to A Add indirect RAM to A Add immediate to A Add register to A with carry Add direct byte to A with carry Add indirect RAM to A with carry Add immediate to A with carry Subtract register from A with borrow Subtract direct byte from A with borrow Subtract indirect RAM from A with borrow Subtract immediate from A with borrow Increment A Increment register Increment direct byte Increment indirect RAM Decrement A Decrement register Decrement direct byte Decrement indirect RAM Increment Data Pointer Multiply A and B Divide A by B Decimal adjust A Logical Operations AND Register to A AND direct byte to A AND indirect RAM to A AND immediate to A AND A to direct byte AND immediate to direct byte OR Register to A Rev. 1.8 Bytes Clock Cycles 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 1 1 2 1 1 1 1 1 1 2 2 2 1 2 2 2 1 2 2 2 1 1 2 2 1 1 2 2 1 4 8 1 1 2 1 2 2 3 1 1 2 2 2 2 3 1 81 C8051F310/1/2/3/4/5/6/7 Table 8.1. CIP-51 Instruction Set Summary (Continued) Mnemonic Description ORL A, direct ORL A, @Ri ORL A, #data ORL direct, A ORL direct, #data XRL A, Rn XRL A, direct XRL A, @Ri XRL A, #data XRL direct, A XRL direct, #data CLR A CPL A RL A RLC A RR A RRC A SWAP A OR direct byte to A OR indirect RAM to A OR immediate to A OR A to direct byte OR immediate to direct byte Exclusive-OR Register to A Exclusive-OR direct byte to A Exclusive-OR indirect RAM to A Exclusive-OR immediate to A Exclusive-OR A to direct byte Exclusive-OR immediate to direct byte Clear A Complement A Rotate A left Rotate A left through Carry Rotate A right Rotate A right through Carry Swap nibbles of A Data Transfer Move Register to A Move direct byte to A Move indirect RAM to A Move immediate to A Move A to Register Move direct byte to Register Move immediate to Register Move A to direct byte Move Register to direct byte Move direct byte to direct byte Move indirect RAM to direct byte Move immediate to direct byte Move A to indirect RAM Move direct byte to indirect RAM Move immediate to indirect RAM Load DPTR with 16-bit constant Move code byte relative DPTR to A Move code byte relative PC to A Move external data (8-bit address) to A Move A to external data (8-bit address) Move external data (16-bit address) to A Move A to external data (16-bit address) Push direct byte onto stack Pop direct byte from stack Exchange Register with A Exchange direct byte with A MOV A, Rn MOV A, direct MOV A, @Ri MOV A, #data MOV Rn, A MOV Rn, direct MOV Rn, #data MOV direct, A MOV direct, Rn MOV direct, direct MOV direct, @Ri MOV direct, #data MOV @Ri, A MOV @Ri, direct MOV @Ri, #data MOV DPTR, #data16 MOVC A, @A+DPTR MOVC A, @A+PC MOVX A, @Ri MOVX @Ri, A MOVX A, @DPTR MOVX @DPTR, A PUSH direct POP direct XCH A, Rn XCH A, direct 82 2 1 2 2 3 1 2 1 2 2 3 1 1 1 1 1 1 1 Clock Cycles 2 2 2 2 3 1 2 2 2 2 3 1 1 1 1 1 1 1 1 2 1 2 1 2 2 2 2 3 2 3 1 2 2 3 1 1 1 1 1 1 2 2 1 2 1 2 2 2 1 2 2 2 2 3 2 3 2 2 2 3 3 3 3 3 3 3 2 2 1 2 Bytes Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Table 8.1. CIP-51 Instruction Set Summary (Continued) Mnemonic Description XCH A, @Ri XCHD A, @Ri Exchange indirect RAM with A Exchange low nibble of indirect RAM with A Boolean Manipulation Clear Carry Clear direct bit Set Carry Set direct bit Complement Carry Complement direct bit AND direct bit to Carry AND complement of direct bit to Carry OR direct bit to carry OR complement of direct bit to Carry Move direct bit to Carry Move Carry to direct bit Jump if Carry is set Jump if Carry is not set Jump if direct bit is set Jump if direct bit is not set Jump if direct bit is set and clear bit Program Branching Absolute subroutine call Long subroutine call Return from subroutine Return from interrupt Absolute jump Long jump Short jump (relative address) Jump indirect relative to DPTR Jump if A equals zero Jump if A does not equal zero Compare direct byte to A and jump if not equal Compare immediate to A and jump if not equal Compare immediate to Register and jump if not equal Compare immediate to indirect and jump if not equal Decrement Register and jump if not zero Decrement direct byte and jump if not zero No operation CLR C CLR bit SETB C SETB bit CPL C CPL bit ANL C, bit ANL C, /bit ORL C, bit ORL C, /bit MOV C, bit MOV bit, C JC rel JNC rel JB bit, rel JNB bit, rel JBC bit, rel ACALL addr11 LCALL addr16 RET RETI AJMP addr11 LJMP addr16 SJMP rel JMP @A+DPTR JZ rel JNZ rel CJNE A, direct, rel CJNE A, #data, rel CJNE Rn, #data, rel CJNE @Ri, #data, rel DJNZ Rn, rel DJNZ direct, rel NOP 1 1 Clock Cycles 2 2 1 2 1 2 1 2 2 2 2 2 2 2 2 2 3 3 3 1 2 1 2 1 2 2 2 2 2 2 2 2/3 2/3 3/4 3/4 3/4 2 3 1 1 2 3 2 1 2 2 3 3 3 4 5 5 3 4 3 3 2/3 2/3 3/4 3/4 3 3/4 3 4/5 2 3 1 2/3 3/4 1 Bytes Rev. 1.8 83 C8051F310/1/2/3/4/5/6/7 Notes on Registers, Operands and Addressing Modes: Rn - Register R0–R7 of the currently selected register bank. @Ri - Data RAM location addressed indirectly through R0 or R1. rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by SJMP and all conditional jumps. direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00– 0x7F) or an SFR (0x80–0xFF). #data - 8-bit constant #data16 - 16-bit constant bit - Direct-accessed bit in Data RAM or SFR addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same 2 kB page of program memory as the first byte of the following instruction. addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within the 8 kB program memory space. There is one unused opcode (0xA5) that performs the same function as NOP. All mnemonics copyrighted © Intel Corporation 1980. 84 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 8.2. Memory Organization The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same address space but are accessed via different instruction types. The CIP-51 memory organization is shown in Figure 8.2. DATA MEMORY (RAM) INTERNAL DATA ADDRESS SPACE PROGRAM/DATA MEMORY (Flash) 0xFF C8051F310/1 0x3E00 RESERVED 0x80 0x7F 0x3DFF Upper 128 RAM (Indirect Addressing Only) (Direct and Indirect Addressing) 16 kB Flash 0x30 0x2F (In-System Programmable in 512 Byte Sectors) 0x20 0x1F 0x00 Bit Addressable Special Function Register's (Direct Addressing Only) Lower 128 RAM (Direct and Indirect Addressing) General Purpose Registers EXTERNAL DATA ADDRESS SPACE 0x0000 0xFFFF C8051F312/3/4/5 0x2000 RESERVED Same 1024 bytes as from 0x0000 to 0x03FF, wrapped on 1 kB boundaries 0x1FFF 8 kB Flash 0x0400 (In-System Programmable in 512 Byte Sectors) 0x03FF 0x0000 XRAM - 1024 Bytes (accessable using MOVX instruction) 0x0000 Figure 8.2. Memory Map 8.2.1. Program Memory The CIP-51 core has a 64k-byte program memory space. The C8051F310/1 and C8051F312/3/4/5 implement 16k and 8 kB, respectively, of this program memory space as in-system, re-programmable Flash memory, organized in a contiguous block from addresses 0x0000 to 0x3FFF or 0x0000 to 0x1FFF. Addresses above 0x3E00 are reserved on the 16 kB devices. Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for nonvolatile data storage. Refer to Section “10. Flash Memory” on page 111 for further details. Rev. 1.8 85 C8051F310/1/2/3/4/5/6/7 8.2.2. Data Memory The CIP-51 includes 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (SFR) but is physically separate from the SFR space. The addressing mode used by an instruction when accessing locations above 0x7F determines whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the upper 128 bytes of data memory. Figure 8.2 illustrates the data memory organization of the CIP-51. 8.2.3. General Purpose Registers The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1 (PSW.4), select the active register bank (see description of the PSW in SFR Definition 8.4). This allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes use registers R0 and R1 as index registers. 8.2.4. Bit Addressable Locations In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20 through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from 0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or destination). The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where XX is the byte address and B is the bit position within the byte. For example, the instruction: MOV C, 22.3h moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag. 8.2.5. Stack A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be initialized to a location in the data memory not being used for data storage. The stack depth can extend up to 256 bytes. 86 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 8.2.6. Special Function Registers The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers (SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new functionality while retaining compatibility with the MCS-51™ instruction set. Table 8.2 lists the SFRs implemented in the CIP-51 System Controller. The SFR registers are accessed anytime the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are bitaddressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 8.3, for a detailed description of each register. Table 8.2. Special Function Register (SFR) Memory Map F8 F0 E8 E0 D8 D0 C8 C0 B8 B0 A8 A0 98 90 88 80 SPI0CN PCA0L PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 B P0MDIN P1MDIN P2MDIN P3MDIN ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 ACC XBR0 XBR1 IT01CF PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PSW REF0CN P0SKIP P1SKIP TMR2CN TMR2RLL TMR2RLH TMR2L TMR2H SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL IP AMX0N AMX0P ADC0CF ADC0L P3 OSCXCN OSCICN OSCICL IE CLKSEL EMI0CN P2 SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT SCON0 SBUF0 CPT1CN CPT0CN CPT1MD CPT0MD P1 TMR3CN TMR3RLL TMR3RLH TMR3L TMR3H TCON TMOD TL0 TL1 TH0 TH1 P0 SP DPL DPH 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) PCA0CPH4 VDM0CN EIP1 PCA0CPH3 RSTSRC EIE1 PCA0CPM4 P2SKIP ADC0LTH ADC0H FLSCL FLKEY P2MDOUT P3MDOUT CPT1MX CPT0MX CKCON 6(E) PSCTL PCON 7(F) (bit addressable) Rev. 1.8 87 C8051F310/1/2/3/4/5/6/7 Table 8.3. Special Function Registers Register Address Description SFRs are listed in alphabetical order. All undefined SFR locations are reserved ACC 0xE0 Accumulator ADC0CF 0xBC ADC0 Configuration ADC0CN 0xE8 ADC0 Control ADC0GTH 0xC4 ADC0 Greater-Than Compare High ADC0GTL 0xC3 ADC0 Greater-Than Compare Low ADC0H 0xBE ADC0 High ADC0L 0xBD ADC0 Low ADC0LTH 0xC6 ADC0 Less-Than Compare Word High ADC0LTL 0xC5 ADC0 Less-Than Compare Word Low AMX0N 0xBA AMUX0 Negative Channel Select AMX0P 0xBB AMUX0 Positive Channel Select B 0xF0 B Register CKCON 0x8E Clock Control CLKSEL 0xA9 Clock Select CPT0CN 0x9B Comparator0 Control CPT0MD 0x9D Comparator0 Mode Selection CPT0MX 0x9F Comparator0 MUX Selection CPT1CN 0x9A Comparator1 Control CPT1MD 0x9C Comparator1 Mode Selection CPT1MX 0x9E Comparator1 MUX Selection DPH 0x83 Data Pointer High DPL 0x82 Data Pointer Low EIE1 0xE6 Extended Interrupt Enable 1 EIP1 0xF6 Extended Interrupt Priority 1 EMI0CN 0xAA External Memory Interface Control FLKEY 0xB7 Flash Lock and Key FLSCL 0xB6 Flash Scale IE 0xA8 Interrupt Enable IP 0xB8 Interrupt Priority IT01CF 0xE4 INT0/INT1 Configuration OSCICL 0xB3 Internal Oscillator Calibration OSCICN 0xB2 Internal Oscillator Control OSCXCN 0xB1 External Oscillator Control P0 0x80 Port 0 Latch P0MDIN 0xF1 Port 0 Input Mode Configuration P0MDOUT 0xA4 Port 0 Output Mode Configuration P0SKIP 0xD4 Port 0 Skip P1 0x90 Port 1 Latch P1MDIN 0xF2 Port 1 Input Mode Configuration P1MDOUT 0xA5 Port 1 Output Mode Configuration P1SKIP 0xD5 Port 1 Skip P2 0xA0 Port 2 Latch P2MDIN 0xF3 Port 2 Input Mode Configuration P2MDOUT 0xA6 Port 2 Output Mode Configuration 88 Rev. 1.8 Page 92 59 60 61 61 59 59 62 62 58 57 93 193 123 72 74 73 75 77 76 91 90 99 100 119 117 117 97 98 101 122 122 125 136 136 137 137 138 138 139 139 140 140 141 C8051F310/1/2/3/4/5/6/7 Table 8.3. Special Function Registers (Continued) Register P2SKIP P3 P3MDIN P3MDOUT PCA0CN PCA0CPH0 PCA0CPH1 PCA0CPH2 PCA0CPH3 PCA0CPH4 PCA0CPL0 PCA0CPL1 PCA0CPL2 PCA0CPL3 PCA0CPL4 PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0H PCA0L PCA0MD PCON PSCTL PSW REF0CN RSTSRC SBUF0 SCON0 SMB0CF SMB0CN SMB0DAT SP SPI0CFG SPI0CKR SPI0CN SPI0DAT TCON TH0 TH1 TL0 TL1 TMOD TMR2CN TMR2H Address 0xD6 0xB0 0xF4 0xA7 0xD8 0xFC 0xEA 0xEC 0xEE 0xFE 0xFB 0xE9 0xEB 0xED 0xFD 0xDA 0xDB 0xDC 0xDD 0xDE 0xFA 0xF9 0xD9 0x87 0x8F 0xD0 0xD1 0xEF 0x99 0x98 0xC1 0xC0 0xC2 0x81 0xA1 0xA2 0xF8 0xA3 0x88 0x8C 0x8D 0x8A 0x8B 0x89 0xC8 0xCD Description Port 2 Skip Port 3 Latch Port 3 Input Mode Configuration Port 3 Output Mode Configuration PCA Control PCA Capture 0 High PCA Capture 1 High PCA Capture 2 High PCA Capture 3High PCA Capture 4 High PCA Capture 0 Low PCA Capture 1 Low PCA Capture 2 Low PCA Capture 3Low PCA Capture 4 Low PCA Module 0 Mode PCA Module 1 Mode PCA Module 2 Mode PCA Module 3 Mode PCA Module 4 Mode PCA Counter High PCA Counter Low PCA Mode Power Control Program Store R/W Control Program Status Word Voltage Reference Control Reset Source Configuration/Status UART0 Data Buffer UART0 Control SMBus Configuration SMBus Control SMBus Data Stack Pointer SPI Configuration SPI Clock Rate Control SPI Control SPI Data Timer/Counter Control Timer/Counter 0 High Timer/Counter 1 High Timer/Counter 0 Low Timer/Counter 1 Low Timer/Counter Mode Timer/Counter 2 Control Timer/Counter 2 High Rev. 1.8 Page 141 142 142 143 215 219 219 219 219 219 218 218 218 218 218 217 217 217 217 217 218 218 216 103 116 92 68 109 169 168 152 154 156 91 180 182 181 182 191 194 194 194 194 192 197 198 89 C8051F310/1/2/3/4/5/6/7 Table 8.3. Special Function Registers (Continued) Register Address TMR2L 0xCC TMR2RLH 0xCB TMR2RLL 0xCA TMR3CN 0x91 TMR3H 0x95 TMR3L 0x94 TMR3RLH 0x93 TMR3RLL 0x92 VDM0CN 0xFF XBR1 0xE2 XBR0 0xE1 0x84-0x86, 0x96-0x97, 0xAB-0xAF, 0xB4, 0xB9, 0xBF, 0xC7, 0xC9, 0xCE, 0xCF, 0xD2, 0xD3, 0xD7, 0xDF, 0xE3, 0xE5, 0xF5 Description Timer/Counter 2 Low Timer/Counter 2 Reload High Timer/Counter 2 Reload Low Timer/Counter 3Control Timer/Counter 3 High Timer/Counter 3Low Timer/Counter 3 Reload High Timer/Counter 3 Reload Low VDD Monitor Control Port I/O Crossbar Control 1 Port I/O Crossbar Control 0 Page 198 198 198 201 202 202 202 202 107 135 134 Reserved 8.2.7. Register Descriptions Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits should not be set to logic 1. Future product versions may use these bits to implement new features in which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sections of the data sheet associated with their corresponding system function. SFR Definition 8.1. DPL: Data Pointer Low Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x82 Bits7–0: DPL: Data Pointer Low. The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly addressed Flash memory. 90 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.2. DPH: Data Pointer High Byte R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0x83 Bits7–0: DPH: Data Pointer High. The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly addressed Flash memory. SFR Definition 8.3. SP: Stack Pointer R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000111 0x81 Bits7–0: SP: Stack Pointer. The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented before every PUSH operation. The SP register defaults to 0x07 after reset. Rev. 1.8 91 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.4. PSW: Program Status Word R/W R/W R/W R/W R/W R/W CY Bit7 R/W R AC F0 RS1 RS0 Bit6 Bit5 Bit4 Bit3 OV F1 PARITY 00000000 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Reset Value 0xD0 Bit7: CY: Carry Flag. This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow (subtraction). It is cleared to logic 0 by all other arithmetic operations. Bit6: AC: Auxiliary Carry Flag This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow from (subtraction) the high order nibble. It is cleared to logic 0 by all other arithmetic operations. Bit5: F0: User Flag 0. This is a bit-addressable, general purpose flag for use under software control. Bits4–3: RS1–RS0: Register Bank Select. These bits select which register bank is used during register accesses. RS1 0 0 1 1 Bit2: Bit1: Bit0: RS0 0 1 0 1 Register Bank 0 1 2 3 Address 0x00–0x07 0x08–0x0F 0x10–0x17 0x18–0x1F OV: Overflow Flag. This bit is set to 1 under the following circumstances: an ADD, ADDC, or SUBB instruction causes a sign-change overflow, a MUL instruction results in an overflow (result is greater than 255), or a DIV instruction causes a divide-by-zero condition. The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other cases. F1: User Flag 1. This is a bit-addressable, general purpose flag for use under software control. PARITY: Parity Flag. This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum is even. SFR Definition 8.5. ACC: Accumulator R/W R/W R/W R/W R/W R/W R/W R/W Reset Value ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Bits7–0: ACC: Accumulator. This register is the accumulator for arithmetic operations. 92 Rev. 1.8 0xE0 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.6. B: B Register R/W R/W R/W R/W R/W R/W R/W R/W B.7 B.6 B.5 B.4 B.3 B.2 B.1 B.0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Reset Value 0xF0 Bits7–0: B: B Register. This register serves as a second accumulator for certain arithmetic operations. 8.3. Interrupt Handler The CIP-51 includes an extended interrupt system supporting a total of 14 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies according to the specific version of the device. Each interrupt source has one or more associated interruptpending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1. If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI instruction, which returns program execution to the next instruction that would have been executed if the interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.) Each interrupt source can be individually enabled or disabled through the use of an associated interrupt enable bit in an SFR (IE-EIE1). However, interrupts must first be globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-enable settings. Note: Any instruction that clears the EA bit should be immediately followed by an instruction that has two or more opcode bytes. For example: // in 'C': EA = 0; // clear EA bit EA = 0; // ... followed by another 2-byte opcode ; in assembly: CLR EA ; clear EA bit CLR EA ; ... followed by another 2-byte opcode If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. However, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is followed by a multi-cycle instruction, the interrupt will not be taken. Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI) Rev. 1.8 93 C8051F310/1/2/3/4/5/6/7 instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction. 8.3.1. MCU Interrupt Sources and Vectors The MCUs support 14 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 8.4 on page 96. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). 94 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 8.3.2. External Interrupts The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or active low; the IT0 and IT1 bits in TCON (Section “17.1. Timer 0 and Timer 1” on page 187) select level or edge sensitive. The table below lists the possible configurations. IT0 1 1 0 0 IN0PL 0 1 0 1 /INT0 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive IT1 1 1 0 0 IN1PL 0 1 0 1 /INT1 Interrupt Active low, edge sensitive Active high, edge sensitive Active low, level sensitive Active high, level sensitive /INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 8.11). Note that /INT0 and /INT0 Port pin assignments are independent of any Crossbar assignments. /INT0 and /INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section “13.1. Priority Crossbar Decoder” on page 131 for complete details on configuring the Crossbar). IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the /INT0 and /INT1 external interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It must then deactivate the interrupt request before execution of the ISR completes or another interrupt request will be generated. 8.3.3. Interrupt Priorities Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is used to arbitrate, given in Table 8.4. 8.3.4. Interrupt Latency Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is 18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction. Rev. 1.8 95 C8051F310/1/2/3/4/5/6/7 Bit addressable? Cleared by HW? Table 8.4. Interrupt Summary N/A N/A IE0 (TCON.1) TF0 (TCON.5) IE1 (TCON.3) TF1 (TCON.7) RI0 (SCON0.0) TI0 (SCON0.1) TF2H (TMR2CN.7) TF2L (TMR2CN.6) SPIF (SPI0CN.7) WCOL (SPI0CN.6) MODF (SPI0CN.5) RXOVRN (SPI0CN.4) Y Y Y Y Y Y Y Y Always Enabled EX0 (IE.0) ET0 (IE.1) EX1 (IE.2) ET1 (IE.3) Y N ES0 (IE.4) PS0 (IP.4) Y N ET2 (IE.5) PT2 (IP.5) Y N ESPI0 (IE.6) 7 SI (SMB0CN.0) Y 0x0043 8 0x004B 9 0x0053 10 0x005B 11 Comparator0 0x0063 12 Comparator1 0x006B 13 Timer 3 Overflow 0x0073 14 N/A AD0WINT (ADC0CN.3) AD0INT (ADC0CN.5) CF (PCA0CN.7) CCFn (PCA0CN.n) CP0FIF (CPT0CN.4) CP0RIF (CPT0CN.5) CP1FIF (CPT1CN.4) CP1RIF (CPT1CN.5) TF3H (TMR3CN.7) TF3L (TMR3CN.6) Interrupt Source Interrupt Priority Pending Flag Vector Order Reset 0x0000 Top External Interrupt 0 (/INT0) Timer 0 Overflow External Interrupt 1 (/INT1) Timer 1 Overflow 0x0003 0x000B 0x0013 0x001B 0 1 2 3 UART0 0x0023 4 Timer 2 Overflow 0x002B 5 SPI0 0x0033 6 SMB0 0x003B RESERVED ADC0 Window Compare ADC0 Conversion Complete Programmable Counter Array 96 None Rev. 1.8 N/A Y Y Y Enable Flag Priority Control Always Highest PX0 (IP.0) PT0 (IP.1) PX1 (IP.2) PT1 (IP.3) ESMB0 (EIE1.0) N/A N/A EWADC0 N (EIE1.2) EADC0 N (EIE1.3) EPCA0 N (EIE1.4) N PSPI0 (IP.6) PSMB0 (EIP1.0) N/A PWADC0 (EIP1.2) PADC0 (EIP1.3) PPCA0 (EIP1.4) N N ECP0 (EIE1.5) PCP0 (EIP1.5) N N ECP1 (EIE1.6) PCP1 (EIP1.6) N N ET3 (EIE1.7) PT3 (EIP1.7) C8051F310/1/2/3/4/5/6/7 8.3.5. Interrupt Register Descriptions The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). SFR Definition 8.7. IE: Interrupt Enable R/W R/W R/W R/W R/W R/W R/W R/W Reset Value EA ESPI0 ET2 ES0 ET1 EX1 ET0 EX0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 0xA8 EA: Enable All Interrupts. This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings. 0: Disable all interrupt sources. 1: Enable each interrupt according to its individual mask setting. ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of the SPI0 interrupts. 0: Disable all SPI0 interrupts. 1: Enable interrupt requests generated by SPI0. ET2: Enable Timer 2 Interrupt. This bit sets the masking of the Timer 2 interrupt. 0: Disable Timer 2 interrupt. 1: Enable interrupt requests generated by the TF2L or TF2H flags. ES0: Enable UART0 Interrupt. This bit sets the masking of the UART0 interrupt. 0: Disable UART0 interrupt. 1: Enable UART0 interrupt. ET1: Enable Timer 1 Interrupt. This bit sets the masking of the Timer 1 interrupt. 0: Disable all Timer 1 interrupt. 1: Enable interrupt requests generated by the TF1 flag. EX1: Enable External Interrupt 1. This bit sets the masking of External Interrupt 1. 0: Disable external interrupt 1. 1: Enable interrupt requests generated by the /INT1 input. ET0: Enable Timer 0 Interrupt. This bit sets the masking of the Timer 0 interrupt. 0: Disable all Timer 0 interrupt. 1: Enable interrupt requests generated by the TF0 flag. EX0: Enable External Interrupt 0. This bit sets the masking of External Interrupt 0. 0: Disable external interrupt 0. 1: Enable interrupt requests generated by the /INT0 input. Rev. 1.8 97 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.8. IP: Interrupt Priority R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - PSPI0 PT2 PS0 PT1 PX1 PT0 PX0 10000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 98 UNUSED. Read = 1, Write = don't care. PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control. This bit sets the priority of the SPI0 interrupt. 0: SPI0 interrupt set to low priority level. 1: SPI0 interrupt set to high priority level. PT2: Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupts set to low priority level. 1: Timer 2 interrupts set to high priority level. PS0: UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupts set to low priority level. 1: UART0 interrupts set to high priority level. PT1: Timer 1 Interrupt Priority Control. This bit sets the priority of the Timer 1 interrupt. 0: Timer 1 interrupts set to low priority level. 1: Timer 1 interrupts set to high priority level. PX1: External Interrupt 1 Priority Control. This bit sets the priority of the External Interrupt 1 interrupt. 0: External Interrupt 1 set to low priority level. 1: External Interrupt 1 set to high priority level. PT0: Timer 0 Interrupt Priority Control. This bit sets the priority of the Timer 0 interrupt. 0: Timer 0 interrupt set to low priority level. 1: Timer 0 interrupt set to high priority level. PX0: External Interrupt 0 Priority Control. This bit sets the priority of the External Interrupt 0 interrupt. 0: External Interrupt 0 set to low priority level. 1: External Interrupt 0 set to high priority level. Rev. 1.8 0xB8 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.9. EIE1: Extended Interrupt Enable 1 R/W R/W R/W R/W R/W ET3 ECP1 ECP0 EPCA0 EADC0 Bit7 Bit6 Bit5 Bit4 Bit3 R/W R/W EWADC0 Reserved Bit2 Bit1 R/W Reset Value ESMB0 00000000 Bit0 SFR Address: 0xE6 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: ET3: Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable Timer 3 interrupts. 1: Enable interrupt requests generated by the TF3L or TF3H flags. ECP1: Enable Comparator1 (CP1) Interrupt. This bit sets the masking of the CP1 interrupt. 0: Disable CP1 interrupts. 1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags. ECP0: Enable Comparator0 (CP0) Interrupt. This bit sets the masking of the CP0 interrupt. 0: Disable CP0 interrupts. 1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags. EPCA0: Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable all PCA0 interrupts. 1: Enable interrupt requests generated by PCA0. EADC0: Enable ADC0 Conversion Complete Interrupt. This bit sets the masking of the ADC0 Conversion Complete interrupt. 0: Disable ADC0 Conversion Complete interrupt. 1: Enable interrupt requests generated by the AD0INT flag. EWADC0: Enable Window Comparison ADC0 Interrupt. This bit sets the masking of ADC0 Window Comparison interrupt. 0: Disable ADC0 Window Comparison interrupt. 1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT). RESERVED. Read = 0. Must Write 0. ESMB0: Enable SMBus (SMB0) Interrupt. This bit sets the masking of the SMB0 interrupt. 0: Disable all SMB0 interrupts. 1: Enable interrupt requests generated by SMB0. Rev. 1.8 99 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.10. EIP1: Extended Interrupt Priority 1 R/W R/W R/W R/W R/W PT3 PCP1 PCP0 PCP0 PADC0 Bit7 Bit6 Bit5 Bit4 Bit3 R/W R/W PWADC0 Reserved Bit2 R/W Reset Value PSMB0 00000000 Bit0 SFR Address: Bit1 0xF6 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 100 PT3: Timer 3 Interrupt Priority Control. This bit sets the priority of the Timer 3 interrupt. 0: Timer 3 interrupts set to low priority level. 1: Timer 3 interrupts set to high priority level. PCP1: Comparator1 (CP1) Interrupt Priority Control. This bit sets the priority of the CP1 interrupt. 0: CP1 interrupt set to low priority level. 1: CP1 interrupt set to high priority level. PCP0: Comparator0 (CP0) Interrupt Priority Control. This bit sets the priority of the CP0 interrupt. 0: CP0 interrupt set to low priority level. 1: CP0 interrupt set to high priority level. PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control. This bit sets the priority of the PCA0 interrupt. 0: PCA0 interrupt set to low priority level. 1: PCA0 interrupt set to high priority level. PADC0 ADC0 Conversion Complete Interrupt Priority Control. This bit sets the priority of the ADC0 Conversion Complete interrupt. 0: ADC0 Conversion Complete interrupt set to low priority level. 1: ADC0 Conversion Complete interrupt set to high priority level. PWADC0: ADC0 Window Comparator Interrupt Priority Control. This bit sets the priority of the ADC0 Window interrupt. 0: ADC0 Window interrupt set to low priority level. 1: ADC0 Window interrupt set to high priority level. RESERVED. Read = 0. Must Write 0. PSMB0: SMBus (SMB0) Interrupt Priority Control. This bit sets the priority of the SMB0 interrupt. 0: SMB0 interrupt set to low priority level. 1: SMB0 interrupt set to high priority level. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 8.11. IT01CF: INT0/INT1 Configuration R/W R/W R/W R/W R/W R/W R/W R/W Reset Value IN1PL IN1SL2 IN1SL1 IN1SL0 IN0PL IN0SL2 IN0SL1 IN0SL0 00000001 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xE4 Note: Refer to SFR Definition 17.1 for INT0/1 edge- or level-sensitive interrupt selection. Bit7: IN1PL: /INT1 Polarity 0: /INT1 input is active low. 1: /INT1 input is active high. Bits6–4: IN1SL2–0: /INT1 Port Pin Selection Bits These bits select which Port pin is assigned to /INT1. Note that this pin assignment is independent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to ‘1’ the corresponding bit in register P0SKIP). IN1SL2–0 000 001 010 011 100 101 110 111 /INT1 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 Bit3: IN0PL: /INT0 Polarity 0: /INT0 interrupt is active low. 1: /INT0 interrupt is active high. Bits2–0: INT0SL2–0: /INT0 Port Pin Selection Bits These bits select which Port pin is assigned to /INT0. Note that this pin assignment is independent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by setting to ‘1’ the corresponding bit in register P0SKIP). IN0SL2–0 000 001 010 011 100 101 110 111 /INT0 Port Pin P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 Rev. 1.8 101 C8051F310/1/2/3/4/5/6/7 8.4. Power Management Modes The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states; the external oscillator is not effected). Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the least power. SFR Definition 8.12 describes the Power Control Register (PCON) used to control the CIP-51's power management modes. Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power management of the entire MCU is better accomplished by enabling/disabling individual peripherals as needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off the oscillators lowers power consumption considerably; however, a reset is required to restart the MCU. 8.4.1. Idle Mode Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon as the instruction that sets the bit completes execution. All internal registers and memory maintain their original data. All analog and digital peripherals can remain active during Idle mode. Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The pending interrupt will be serviced and the next instruction to be executed after the return from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. Refer to Section “9.6. PCA Watchdog Timer Reset” on page 108 for more information on the use and configuration of the WDT. Note: Any instruction that sets the IDLE bit should be immediately followed by an instruction that has 2 or more opcode bytes. For example: // in 'C': PCON |= 0x01; // set IDLE bit PCON = PCON; // ... followed by a 3-cycle dummy instruction ; in assembly: ORL PCON, #01h ; set IDLE bit MOV PCON, PCON; ... followed by a 3-cycle dummy instruction If the instruction following the write of the IDLE bit is a single-byte instruction and an interrupt occurs during the execution phase of the instruction that sets the IDLE bit, the CPU may not wake from IDLE mode when a future interrupt occurs. 102 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 8.4.2. Stop Mode Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset sequence and begins program execution at address 0x0000. If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode. The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the MCD timeout of 100 µsec. SFR Definition 8.12. PCON: Power Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value GF5 GF4 GF3 GF2 GF1 GF0 STOP IDLE 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x87 Bits7–2: GF5–GF0: General Purpose Flags 5–0. These are general purpose flags for use under software control. Bit1: STOP: Stop Mode Select. Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0. 1: CPU goes into Stop mode (internal oscillator stopped). Bit0: IDLE: Idle Mode Select. Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0. 1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial Ports, and Analog Peripherals are still active.) Rev. 1.8 103 C8051F310/1/2/3/4/5/6/7 NOTES: 104 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 9. Reset Sources Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this reset state, the following occur: • • • • CIP-51 halts program execution Special Function Registers (SFRs) are initialized to their defined reset values External Port pins are forced to a known state Interrupts and timers are disabled. All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal data memory are unaffected during a reset; any previously stored data is preserved. However, since the stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered. The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled during and after the reset. For VDD Monitor and power-on resets, the RST pin is driven low until the device exits the reset state. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section “12. Oscillators” on page 121 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 “18.3. Watchdog Timer Mode” on page 212 details the use of the Watchdog Timer). Program execution begins at location 0x0000. VDD Power On Reset Supply Monitor '0' Enable (wired-OR) /RST + C0RSEF Missing Clock Detector (oneshot) EN Reset Funnel PCA WDT (Software Reset) SWRSF Errant FLASH Operation EN System Clock WDT Enable Px.x + - Comparator 0 MCD Enable Px.x CIP-51 Microcontroller Core System Reset Extended Interrupt Handler Figure 9.1. Reset Sources Rev. 1.8 105 C8051F310/1/2/3/4/5/6/7 9.1. Power-On Reset During power-up, the device is held in a reset state and the RST pin is driven low until VDD settles above VRST. An additional delay occurs before the device is released from reset; the delay decreases as the VDD ramp time increases (VDD ramp time is defined as how fast VDD ramps from 0 V to VRST). Figure 9.2. plots the power-on and VDD monitor reset timing. For valid ramp times (less than 1 ms), the power-on reset delay (TPORDelay) is typically less than 0.3 ms. Note: The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to be released from reset before VDD reaches the VRST 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 content of internal data memory should be assumed to be undefined after a power-on reset. The VDD monitor is disabled following a power-on reset. VDD 2.70 2.55 VRST VD D 2.0 1.0 t Logic HIGH Logic LOW /RST TPORDelay VDD Monitor Reset Power-On Reset Figure 9.2. Power-On and VDD Monitor Reset Timing 9.2. Power-Fail Reset / VDD Monitor When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply monitor will drive the RST pin low and hold the CIP-51 in a reset state (see Figure 9.2). When VDD returns to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be valid. The VDD monitor is disabled after power-on resets; however its defined state (enabled/disabled) is not altered by 106 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 any other reset source. For example, if the VDD monitor is enabled and a software reset is performed, the VDD monitor will still be enabled after the reset. Important Note: The VDD monitor must be enabled before it is selected as a reset source. Selecting the VDD monitor as a reset source before it is enabled and stabilized may cause a system reset. The procedure for configuring the VDD monitor as a reset source is shown below: Step 1. Enable the VDD monitor (VDMEN bit in VDM0CN = ‘1’). Step 2. Wait for the VDD monitor to stabilize (see Table 9.1 for the VDD Monitor turn-on time). Note: This delay should be omitted if software contains routines that erase or write Flash memory. Step 3. Select the VDD monitor as a reset source (PORSF bit in RSTSRC = ‘1’). See Figure 9.2 for VDD monitor timing; note that the reset delay is not incurred after a VDD monitor reset. See Table 9.1 for complete electrical characteristics of the VDD monitor. SFR Definition 9.1. VDM0CN: VDD Monitor Control R/W R R R R R R R VDMEN VDDSTAT Reserved Reserved Reserved Reserved Reserved Reserved Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Reset Value Variable Bit0 SFR Address: 0xFF Bit7: VDMEN: VDD Monitor Enable. This bit is turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system resets until it is also selected as a reset source in register RSTSRC (Figure 9.2). The VDD Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the VDD monitor as a reset source before it has stabilized may generate a system reset. See Table 9.1 for the minimum VDD Monitor turn-on time. 0: VDD Monitor Disabled. 1: VDD Monitor Enabled. Bit6: VDD STAT: VDD Status. This bit indicates the current power supply status (VDD Monitor output). 0: VDD is at or below the VDD monitor threshold. 1: VDD is above the VDD monitor threshold. Bits5–0: Reserved. Read = Variable. Write = don’t care. 9.3. 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 9.1 for complete RST pin specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset. Rev. 1.8 107 C8051F310/1/2/3/4/5/6/7 9.4. Missing Clock Detector Reset The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise, this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables it. The state of the RST pin is unaffected by this reset. 9.5. Comparator0 Reset Comparator0 can be configured as a reset source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), the device is put into the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset. 9.6. 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 “18.3. Watchdog Timer Mode” on page 212; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to ‘1’. The state of the RST pin is unaffected by this reset. 9.7. 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 address 0x3DFF for C8051F310/1 or 0x1FFF for C8051F312/3/4/5. A Flash read is attempted above user code space. This occurs when a MOVC operation targets an address above address 0x3DFF for C8051F310/1 or 0x1FFF for C8051F312/3/4/5. A Program read is attempted above user code space. This occurs when user code attempts to branch to an address above 0x3DFF for C8051F310/1 or 0x1FFF for C8051F312/3/4/5. A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section “10.3. Security Options” on page 113). The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by this reset. 9.8. 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. 108 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 9.2. RSTSRC: Reset Source R Bit7 R R/W FERROR C0RSEF Bit6 Bit5 R/W SWRSF Bit4 R R/W WDTRSF MCDRSF Bit3 Bit2 R/W R Reset Value PORSF PINRSF Variable Bit1 Bit0 SFR Address: 0xEF Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: Note: UNUSED. Read = 0. Write = don’t care. FERROR: Flash Error Indicator. 0: Source of last reset was not a Flash read/write/erase error. 1: Source of last reset was a Flash read/write/erase error. C0RSEF: Comparator0 Reset Enable and Flag. 0: Read: Source of last reset was not Comparator0. Write: Comparator0 is not a reset source. 1: Read: Source of last reset was Comparator0. Write: Comparator0 is a reset source (active-low). SWRSF: Software Reset Force and Flag. 0: Read: Source of last reset was not a write to the SWRSF bit. Write: No Effect. 1: Read: Source of last was a write to the SWRSF bit. Write: Forces a system reset. WDTRSF: Watchdog Timer Reset Flag. 0: Source of last reset was not a WDT timeout. 1: Source of last reset was a WDT timeout. MCDRSF: Missing Clock Detector Flag. 0: Read: Source of last reset was not a Missing Clock Detector timeout. Write: Missing Clock Detector disabled. 1: Read: Source of last reset was a Missing Clock Detector timeout. Write: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected. PORSF: Power-On Reset Force and Flag. This bit is set anytime a power-on reset occurs. Writing this bit enables/disables the VDD monitor as a reset source. Note: writing ‘1’ to this bit before the VDD monitor is enabled and stabilized may cause a system reset. See register VDM0CN (Figure 9.1) 0: Read: Last reset was not a power-on or VDD monitor reset. Write: VDD monitor is not a reset source. 1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate. Write: VDD monitor is a reset source. PINRSF: HW Pin Reset Flag. 0: Source of last reset was not RST pin. 1: Source of last reset was RST pin. For bits that act as both reset source enables (on a write) and reset indicator flags (on a read), read-modify-write instructions read and modify the source enable only. This applies to bits: C0RSEF, SWRSF, MCDRSF, PORSF. Rev. 1.8 109 C8051F310/1/2/3/4/5/6/7 Table 9.1. Reset Electrical Characteristics –40 to +85 °C unless otherwise specified. Parameter Min Typ Max Units — — 0.6 V RST Input High Voltage 0.7 x VDD — — V RST Input Low Voltage — — 0.3 x VDD — 25 40 µA 2.40 2.55 2.70 V RST Output Low Voltage RST Input Pullup Current Conditions IOL = 8.5 mA, VDD = 2.7 to 3.6 V RST = 0.0 V VDD Monitor Threshold (VRST) Missing Clock Detector Timeout Time from last system clock rising edge to reset initiation 100 220 600 µs Reset Time Delay Delay between release of any reset source and code execution at location 0x0000 5.0 — — µs Minimum RST Low Time to Generate a System Reset 15 — — µs VDD Monitor Turn-on Time 100 — — µs — 20 50 µA — — 1 ms VDD Monitor Supply Current VDD Ramp Time 110 VDD = 0 V to VDD = 2.7 V Rev. 1.8 C8051F310/1/2/3/4/5/6/7 10. Flash Memory On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The Flash memory can be programmed in-system, a single byte at a time, through the C2 interface or by software using the MOVX instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. Flash bytes would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. Code execution is stalled during a Flash write/erase operation. Refer to Table 10.1 for complete Flash memory electrical characteristics. 10.1. Programming The Flash Memory The simplest means of programming the Flash memory is through the C2 interface using programming tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initialized device. For details on the C2 commands to program Flash memory, see Section “20. C2 Interface” on page 223. To ensure the integrity of Flash contents, it is strongly recommended that the on-chip VDD Monitor be enabled in any system that includes code that writes and/or erases Flash memory from software. 10.1.1. Flash Lock and Key Functions Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash write or erase is attempted before the key codes have been written properly. The Flash lock resets after each write or erase; the key codes must be written again before a following Flash operation can be performed. The FLKEY register is detailed in SFR Definition 10.2. 10.1.2. Flash Erase Procedure The Flash memory can be programmed from software using the MOVX write instruction with the address and data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX, Flash write operations must be enabled by: (1) setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the Flash key codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared by software. A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written. The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps: Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Disable interrupts (recommended). Set the PSEE bit (register PSCTL). Set the PSWE bit (register PSCTL). Write the first key code to FLKEY: 0xA5. Write the second key code to FLKEY: 0xF1. Using the MOVX instruction, write a data byte to any location within the 512-byte page to be erased. Rev. 1.8 111 C8051F310/1/2/3/4/5/6/7 10.1.3. Flash Write Procedure Flash bytes are programmed by software with the following sequence: Step 1. Disable interrupts (recommended). Step 2. Erase the 512-byte Flash page containing the target location, as described in Section 10.1.2. Step 3. Set the PSWE bit (register PSCTL). Step 4. Clear the PSEE bit (register PSCTL). Step 5. Write the first key code to FLKEY: 0xA5. Step 6. Write the second key code to FLKEY: 0xF1. Step 7. Using the MOVX instruction, write a single data byte to the desired location within the 512 byte sector. Steps 5–7 must be repeated for each byte to be written. After Flash writes are complete, PSWE should be cleared so that MOVX instructions do not target program memory. Table 10.1. Flash Electrical Characteristics VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified. Parameter Conditions Min C8051F310/1/6/7 16384* Flash Size C8051F312/3/4/5 8192 Endurance 20 k Erase Cycle Time 25 MHz System Clock 10 Write Cycle Time 25 MHz System Clock 40 Typ — — 100 k 15 55 Max — — — 20 70 Units bytes Erase/Write ms µs *Note: 512 bytes at locations 0x3E00 (C8051F310/1) are reserved. 10.2. Non-volatile Data Storage The Flash memory can be used for non-volatile data storage as well as program code. This allows data such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM. 112 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 10.3. Security Options The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as to prevent the viewing of proprietary program code and constants. The Program Store Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before software can erase Flash memory. Additional security features prevent proprietary program code and data constants from being read or altered across the C2 interface. A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to 0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the page containing the Flash Security Lock Byte is unlocked when no other Flash pages are locked (all bits of the Lock Byte are ‘1’) and locked when any other Flash pages are locked (any bit of the Lock Byte is ‘0’). See the example below. Security Lock Byte: 1’s Complement: Flash pages locked: 11111101b 00000010b 3 (First two Flash pages + Lock Byte Page) Addresses locked: 0x0000 to 0x03FF (first two Flash pages) and 0x3C00 to 0x3DFF or 0x1E00 to 0x1FFF (Lock Byte Page) C8051F310/1/6/7 C8051F312/3/4/5 Reserved Reserved 0x3E00 Locked when any other FLASH pages are locked Lock Byte 0x2000 Lock Byte 0x3DFF 0x1FFF 0x3DFE 0x1FFE 0x3C00 0x1E00 Unlocked FLASH Pages FLASH memory organized in 512-byte pages Unlocked FLASH Pages Access limit set according to the FLASH security lock byte 0x0000 0x0000 Figure 10.1. Flash Program Memory Map Rev. 1.8 113 C8051F310/1/2/3/4/5/6/7 The level of Flash security depends on the Flash access method. The three Flash access methods that can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on unlocked pages, and user firmware executing on locked pages. Table 10.2 summarizes the Flash security features of the C8051F31x devices. Table 10.2. Flash Security Summary Action C2 Debug Interface User Firmware executing from: an unlocked page a locked page Permitted Permitted Permitted Not Permitted Flash Error Reset Permitted Read or Write page containing Lock Byte (if no pages are locked) Permitted Permitted Permitted Read or Write page containing Lock Byte (if any page is locked) Not Permitted Flash Error Reset Permitted Read contents of Lock Byte (if no pages are locked) Permitted Permitted Permitted Read contents of Lock Byte (if any page is locked) Not Permitted Flash Error Reset Permitted Read, Write or Erase unlocked pages (except page with Lock Byte) Read, Write or Erase locked pages (except page with Lock Byte) Erase page containing Lock Byte (if no pages are locked) Permitted Flash Error Reset Flash Error Reset C2 Device Erase Only Flash Error Reset Flash Error Reset Lock additional pages (change '1's to '0's in the Lock Byte) Not Permitted Flash Error Reset Flash Error Reset Unlock individual pages (change '0's to '1's in the Lock Byte) Not Permitted Flash Error Reset Flash Error Reset Read, Write or Erase Reserved Area Not Permitted Flash Error Reset Flash Error Reset Erase page containing Lock Byte - Unlock all pages (if any page is locked)  C2 Device Erase - Erases all Flash pages including the page containing the Lock Byte. Flash Error Reset - Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after reset). - All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset). - Locking any Flash page also locks the page containing the Lock Byte. - Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase. - If user code writes to the Lock Byte, the Lock does not take effect until the next device reset. 114 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 10.4. Flash Write and Erase Guidelines Any system which contains routines which write or erase Flash memory from software involves some risk that the write or erase routines will execute unintentionally if the CPU is operating outside its specified operating range of VDD, system clock frequency, or temperature. This accidental execution of Flash modifying code can result in alteration of Flash memory contents causing a system failure that is only recoverable by re-Flashing the code in the device. The following guidelines are recommended for any system that contains routines which write or erase Flash from code. 10.4.1. VDD Maintenance and the VDD Monitor 1. If the system power supply is subject to voltage or current "spikes," add sufficient transient protection devices to the power supply to ensure that the supply voltages listed in the Absolute Maximum Ratings table are not exceeded. 2. Make certain that the minimum VDD rise time specification of 1 ms is met. If the system cannot meet this rise time specification, then add an external VDD brownout circuit to the RST pin of the device that holds the device in reset until VDD reaches 2.7 V and re-asserts RST if VDD drops below 2.7 V. 3. Enable the on-chip VDD monitor and enable the VDD monitor as a reset source as early in code as possible. This should be the first set of instructions executed after the Reset Vector. For 'C'based systems, this will involve modifying the startup code added by the 'C' compiler. See your compiler documentation for more details. Make certain that there are no delays in software between enabling the VDD monitor and enabling the VDD monitor as a reset source. Code examples showing this can be found in "AN201: Writing to Flash from Firmware", available from the Silicon Laboratories web site. 4. As an added precaution, explicitly enable the VDD monitor and enable the VDD monitor as a reset source inside the functions that write and erase Flash memory. The VDD monitor enable instructions should be placed just after the instruction to set PSWE to a '1', but before the Flash write or erase operation instruction. 5. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment operators and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC = 0x02" is correct. "RSTSRC |= 0x02" is incorrect. 6. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a '1'. Areas to check are initialization code which enables other reset sources, such as the Missing Clock Detector or Comparator, for example, and instructions which force a Software Reset. A global search on "RSTSRC" can quickly verify this. 10.4.2. PSWE Maintenance 7. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a '1'. There should be exactly one routine in code that sets PSWE to a '1' to write Flash bytes and one routine in code that sets PSWE and PSEE both to a '1' to erase Flash pages. 8. Minimize the number of variable accesses while PSWE is set to a '1'. Handle pointer address updates and loop variable maintenance outside the "PSWE = 1; ... PSWE = 0;" area. Code examples showing this can be found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site. 9. Disable interrupts prior to setting PSWE to a '1' and leave them disabled until after PSWE has been reset to '0'. Any interrupts posted during the Flash write or erase operation will be serviced in priority order after the Flash operation has been completed and interrupts have been re-enabled by software. Rev. 1.8 115 C8051F310/1/2/3/4/5/6/7 10. Make certain that the Flash write and erase pointer variables are not located in XRAM. See your compiler documentation for instructions regarding how to explicitly locate variables in different memory areas. 11. Add address bounds checking to the routines that write or erase Flash memory to ensure that a routine called with an illegal address does not result in modification of the Flash. 10.4.3. System Clock 12. If operating from an external crystal, be advised that crystal performance is susceptible to electrical interference and is sensitive to layout and to changes in temperature. If the system is operating in an electrically noisy environment, use the internal oscillator or use an external CMOS clock. 13. If operating from the external oscillator, switch to the internal oscillator during Flash write or erase operations. The external oscillator can continue to run, and the CPU can switch back to the external oscillator after the Flash operation has completed. Additional Flash recommendations and example code can be found in AN201, "Writing to Flash from Firmware", available from the Silicon Laboratories web site. SFR Definition 10.1. PSCTL: Program Store R/W Control R/W R/W R/W R/W R/W R/W R/W R/W Reset Value - - - - - - PSEE PSWE 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0x8F Bits7–2: UNUSED: Read = 000000b, Write = don’t care. Bit1: PSEE: Program Store Erase Enable Setting this bit (in combination with PSWE) allows an entire page of Flash program memory to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter. 0: Flash program memory erasure disabled. 1: Flash program memory erasure enabled. Bit0: PSWE: Program Store Write Enable Setting this bit allows writing a byte of data to the Flash program memory using the MOVX write instruction. The Flash location should be erased before writing data. 0: Writes to Flash program memory disabled. 1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash memory. 116 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 10.2. FLKEY: Flash Lock and Key R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xB7 Bits7–0: FLKEY: Flash Lock and Key Register Write: This register must be written to before Flash writes or erases can be performed. Flash remains locked until this register is written to with the following key codes: 0xA5, 0xF1. The timing of the writes does not matter, as long as the codes are written in order. The key codes must be written for each Flash write or erase operation. Flash will be locked until the next system reset if the wrong codes are written or if a Flash operation is attempted before the codes have been written correctly. Read: When read, bits 1-0 indicate the current Flash lock state. 00: Flash is write/erase locked. 01: The first key code has been written (0xA5). 10: Flash is unlocked (writes/erases allowed). 11: Flash writes/erases disabled until the next reset. SFR Definition 10.3. FLSCL: Flash Scale R/W FOSE Bit7 R/W R/W R/W R/W R/W R/W R/W Reset Value Reserved Reserved Reserved Reserved Reserved Reserved Reserved 10000000 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xB6 Bits7: FOSE: Flash One-shot Enable This bit enables the Flash read one-shot. When the Flash one-shot disabled, the Flash sense amps are enabled for a full clock cycle during Flash reads. At system clock frequencies below 10 MHz, disabling the Flash one-shot will increase system power consumption. 0: Flash one-shot disabled. 1: Flash one-shot enabled. Bits6–0: RESERVED. Read = 0. Must Write 0. Rev. 1.8 117 C8051F310/1/2/3/4/5/6/7 NOTES: 118 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 11. External RAM The C8051F31x devices include 1024 bytes of RAM mapped into the external data memory space. All of these address locations may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in SFR Definition 11.1). Note: the MOVX instruction is also used for writes to the Flash memory. See Section “10. Flash Memory” on page 111 for details. The MOVX instruction accesses XRAM by default. For a 16-bit MOVX operation (@DPTR), the upper 6-bits of the 16-bit external data memory address word are "don't cares.” As a result, the 1024 byte RAM is mapped modulo style over the entire 64 k external data memory address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses 0x0400, 0x0800, 0x0C00, 0x1000, etc. This is a useful feature when performing a linear memory fill, as the address pointer doesn't have to be reset when reaching the RAM block boundary. SFR Definition 11.1. EMI0CN: External Memory Interface Control R/W R/W R/W R/W R/W R/W R/W R/W PGSEL Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Reset Value 00000000 Bit0 SFR Address: 0xAA Bits 7–2: UNUSED. Read = 000000b. Write = don’t care. Bits 1–0: PGSEL: XRAM Page Select. The EMI0CN register provides the high byte of the 16-bit external data memory address when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. Since the upper (unused) bits of the register are always zero, the PGSEL determines which page of XRAM is accessed. For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed. Rev. 1.8 119 C8051F310/1/2/3/4/5/6/7 NOTES: 120 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 12. Oscillators C8051F31x devices include a programmable internal oscillator and an external oscillator drive circuit. The internal oscillator can be enabled/disabled and calibrated using the OSCICN and OSCICL registers, as shown in Figure 12.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or a scaled version of the internal oscillator. The internal oscillator's electrical specifications are given in Table 12.1 on page 123. XTAL2 EN Option 4 XTAL2 Option 2 VDD CLKSL0 Option 3 CLKSEL IFCN1 IFCN0 OSCICN IOSCEN IFRDY OSCICL Programmable Internal Clock Generator n SYSCLK Option 1 XTAL1 Input Circuit 10M XTAL2 OSC XFCN2 XFCN1 XFCN0 XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 XTAL2 OSCXCN Figure 12.1. Oscillator Diagram 12.1. Programmable Internal Oscillator All C8051F31x devices include a programmable internal oscillator that defaults as the system clock after a system reset. The internal oscillator period can be programmed via the OSCICL register as defined by SFR Definition 12.1 OSCICL is factor calibrated to obtain a 24.5 MHz frequency. Electrical specifications for the precision internal oscillator are given in Table 12.1 on page 123. Note that the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset. Rev. 1.8 121 C8051F310/1/2/3/4/5/6/7 SFR Definition 12.1. OSCICL: Internal Oscillator Calibration R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: Variable 0xB3 Bit7: UNUSED. Read = 0. Write = don’t care. Bits 6–0: OSCICL: Internal Oscillator Calibration Register. This register determines the internal oscillator period. This reset value for OSCICL determines the oscillator base frequency. The reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz. SFR Definition 12.2. OSCICN: Internal Oscillator Control R/W R IOSCEN IFRDY Bit7 Bit6 R/W Bit5 R/W Bit4 R/W Bit3 R/W R/W R/W Reset Value IFCN1 IFCN0 11000000 Bit1 Bit0 SFR Address: Bit2 0xB2 Bit7: IOSCEN: Internal Oscillator Enable Bit. 0: Internal Oscillator Disabled. 1: Internal Oscillator Enabled. Bit6: IFRDY: Internal Oscillator Frequency Ready Flag. 0: Internal Oscillator is not running at programmed frequency. 1: Internal Oscillator is running at programmed frequency. Bits5–2: UNUSED. Read = 0000b, Write = don't care. Bits1–0: IFCN1-0: Internal Oscillator Frequency Control Bits. 00: SYSCLK derived from Internal Oscillator divided by 8. 01: SYSCLK derived from Internal Oscillator divided by 4. 10: SYSCLK derived from Internal Oscillator divided by 2. 11: SYSCLK derived from Internal Oscillator divided by 1. 122 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 12.3. CLKSEL: Clock Select R/W R/W R/W R/W R/W R/W R/W R/W Reserved Reserved Reserved Reserved Reserved Reserved Reserved Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Reset Value CLKSL0 00000000 Bit0 SFR Address: Bit1 0xA9 Bits7–1: Reserved. Read = 0000000b, Must Write = 0000000. Bit0: CLKSL0: System Clock Source Select Bit. 0: SYSCLK derived from the Internal Oscillator, and scales per the IFCN bits in register OSCICN. 1: SYSCLK derived from the External Oscillator circuit. Table 12.1. Internal Oscillator Electrical Characteristics VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified. Parameter Conditions Internal Oscillator Frequency Internal Oscillator Supply OSCICN.7 = 1 Current (from VDD) Rev. 1.8 Min 24 Typ 24.5 Max 25 Units MHz — 450 1000 µA 123 C8051F310/1/2/3/4/5/6/7 12.2. External Oscillator Drive Circuit The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 12.1. A 10 Mresistor also must be wired across the XTAL2 and XTAL1 pins for the crystal/resonator configuration. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown in Option 2, 3, or 4 of Figure 12.1. The type of external oscillator must be selected in the OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 12.4). Important Note on External Oscillator Usage: Port pins must be configured when using the external oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar should be configured to skip the Port pins used by the oscillator circuit; see Section “13.1. Priority Crossbar Decoder” on page 131 for Crossbar configuration. Additionally, when using the external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs. In CMOS clock mode, the associated pin should be configured as a digital input. See Section “13.2. Port I/O Initialization” on page 133 for details on Port input mode selection. 12.3. System Clock Selection The CLKSL0 bit in register CLKSEL selects which oscillator is used as the system clock. CLKSL0 must be set to ‘1’ for the system clock to run from the external oscillator; however the external oscillator may still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The system clock may be switched on-the-fly between the internal and external oscillator, so long as the selected oscillator is enabled and has settled. The internal oscillator requires little start-up time and may be selected as the system clock immediately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use as the system clock. The Crystal Valid Flag (XTLVLD in register OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid reading a false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external oscillator and checking XTLVLD. RC and C modes typically require no startup time. 124 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 12.4. OSCXCN: External Oscillator Control R R/W R/W R/W R XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 Bit7 Bit6 Bit5 Bit4 R/W R/W R/W Reset Value XFCN2 XFCN1 XFCN0 00000000 Bit2 Bit1 Bit0 SFR Address: Bit3 0xB1 Bit7: XTLVLD: Crystal Oscillator Valid Flag. (Read only when XOSCMD = 11x.) 0: Crystal Oscillator is unused or not yet stable. 1: Crystal Oscillator is running and stable. Bits6–4: XOSCMD2-0: External Oscillator Mode Bits. 00x: External Oscillator circuit off. 010: External CMOS Clock Mode. 011: External CMOS Clock Mode with divide by 2 stage. 100: RC Oscillator Mode. 101: Capacitor Oscillator Mode. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. Bit3: RESERVED. Read = 0, Write = don't care. Bits2–0: XFCN2-0: External Oscillator Frequency Control Bits. 000-111: See table below: XFCN 000 001 010 011 100 101 110 111 Crystal (XOSCMD = 11x) f  32 kHz 32 kHz f 84 kHz 84 kHz  f 225 kHz 225 kHz  f 590 kHz 590 kHz  f 1.5 MHz 1.5 MHz  f 4 MHz 4 MHz  f 10 MHz 10 MHz  f 30 MHz RC (XOSCMD = 10x) f 25 kHz 25 kHz f 50 kHz 50 kHz f 100 kHz 100 kHz f 200 kHz 200 kHz f 400 kHz 400 kHz f 800 kHz 800 kHz f 1.6 MHz 1.6 MHz f 3.2 MHz C (XOSCMD = 10x) K Factor = 0.87 K Factor = 2.6 K Factor = 7.7 K Factor = 22 K Factor = 65 K Factor = 180 K Factor = 664 K Factor = 1590 CRYSTAL MODE (Circuit from Figure 12.1, Option 1; XOSCMD = 11x) Choose XFCN value to match crystal frequency. RC MODE (Circuit from Figure 12.1, Option 2; XOSCMD = 10x) Choose XFCN value to match frequency range: f = 1.23(103) / (R x C), where f = frequency of clock in MHz C = capacitor value in pF R = Pullup resistor value in k C MODE (Circuit from Figure 12.1, Option 3; XOSCMD = 10x) Choose K Factor (KF) for the oscillation frequency desired: f = KF / (C x VDD), where f = frequency of clock in MHz C = capacitor value the XTAL2 pin in pF VDD = Power Supply on MCU in volts Rev. 1.8 125 C8051F310/1/2/3/4/5/6/7 12.4. External Crystal Example If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 12.1, Option 1. The External Oscillator Frequency Control value (XFCN) should be chosen from the Crystal column of the table in SFR Definition 12.4. For example, an 11.0592 MHz crystal requires an XFCN setting of 111b. When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is: Step 1. Step 2. Step 3. Step 4. Step 5. Step 6. Force the XTAL1 and XTAL2 pins low by writing 0s to the port latch. Configure XTAL1 and XTAL2 as analog inputs. Enable the external oscillator. Wait at least 1 ms. Poll for XTLVLD => '1'. Switch the system clock to the external oscillator. Note: Tuning-fork crystals may require additional settling time before XTLVLD returns a valid result. The capacitors shown in the external crystal configuration provide the load capacitance required by the crystal for correct oscillation. These capacitors are "in series" as seen by the crystal and "in parallel" with the stray capacitance of the XTAL1 and XTAL2 pins. Note: The load capacitance depends upon the crystal and the manufacturer. Please refer to the crystal data sheet when completing these calculations. For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should use the configuration shown in Figure 12.1, Option 1. The total value of the capacitors and the stray capacitance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 12.2. 22 pF XTAL1 10 M 32.768 kHz XTAL2 22 pF Figure 12.2. 32.768 kHz External Crystal Example Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as short as possible and shielded with ground plane from any other traces which could introduce noise or interference. 126 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 12.5. External RC Example If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 12.1, Option 2. The capacitor should be no greater than 100 pF; however, for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first select the RC network value to produce the desired frequency of oscillation. If the frequency desired is 100 kHz, let R = 246 k and C = 50 pF: f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 x 50 ] = 0.1 MHz = 100 kHz Referring to the table in SFR Definition 12.4, the required XFCN setting is 010b. 12.6. External Capacitor Example If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in Figure 12.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and C = 50 pF: f = KF / ( C x VDD ) = KF / ( 50 x 3 ) MHz f = KF / 150 MHz If a frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 12.4 as KF = 22: f = 22 / 150 = 0.146 MHz, or 146 kHz Therefore, the XFCN value to use in this example is 011b. Rev. 1.8 127 C8051F310/1/2/3/4/5/6/7 NOTES: 128 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 13. Port Input/Output Digital and analog resources are available through 29 I/O pins (C8051F310/2/4), or 25 I/O pins (C8051F311/3/5), or 21 I/O pins (C8051F316/7). Port pins are organized as three byte-wide Ports and one 5-bit-wide (C8051F310/2/4) or 1-bit-wide (C8051F311/3/5) Port. In the C8051F316/7, the port pins are organized as one byte-wide Port, two 6-bit-wide Ports and one 1-bit-wide Port. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog input; Port pins P0.0-P2.3 can be assigned to one of the internal digital resources as shown in Figure 13.3. The designer has complete control over which functions are assigned, limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. The state of a Port I/O pin can always be read in the corresponding Port latch, regardless of the Crossbar settings. The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder (Figure 13.3 and Figure 13.4). The registers XBR0 and XBR1, defined in SFR Definition 13.1 and SFR Definition 13.2, are used to select internal digital functions. All Port I/Os are 5 V tolerant (refer to Figure 13.2 for the Port cell circuit). The Port I/O cells are configured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2,3). Complete Electrical Specifications for Port I/O are given in Table 13.1 on page 143. XBR0, XBR1, PnSKIP Registers PnMDOUT, PnMDIN Registers Priority Decoder Highest Priority UART 4 SPI (Internal Digital Signals) 2 SMBus 8 P0 I/O Cells P0.0 P1 I/O Cells P1.0 P2 I/O Cells P2.0 CP0 Outputs 2 CP1 Outputs 2 Digital Crossbar 8 4 8 SYSCLK P3 I/O Cells P3.0 4 5 T0, T1 2 P2.7 P3.4 Notes: 1. P3.1-P3.4 only available on the C8051F310/2/4 2. P1.6,P1.7,P2.6,P2.7 only available on the C8051F310/1/2/3/4/5 8 P0 (P0.0-P0.7) P1 (P1.0-P1.7) 8 (Port Latches) P1.7 6 PCA Lowest Priority P0.7 2 4 (P2.0-P2.3) P2 4 (P2.4-P2.7) 5 P3 (P3.0-P3.4) Figure 13.1. Port I/O Functional Block Diagram Rev. 1.8 129 C8051F310/1/2/3/4/5/6/7 /WEAK-PULLUP VDD PUSH-PULL /PORT-OUTENABLE VDD (WEAK) PORT PAD PORT-OUTPUT GND Analog Select ANALOG INPUT PORT-INPUT Figure 13.2. Port I/O Cell Block Diagram 130 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 13.1. Priority Crossbar Decoder The Priority Crossbar Decoder (Figure 13.3) assigns a priority to each I/O function, starting at the top with UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that are to be used for analog input, dedicated functions, or GPIO. Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.3 and/or P0.2 if the external oscillator circuit is enabled, P0.6 if the ADC is configured to use the external conversion start signal (CNVSTR), and any selected ADC or Comparator inputs. The Crossbar skips selected pins as if they were already assigned, and moves to the next unassigned pin. Figure 13.3 shows the Crossbar Decoder priority with no Port pins skipped (P0SKIP, P1SKIP, P2SKIP = 0x00); Figure 13.4 shows the Crossbar Decoder priority with the XTAL1 (P0.2) and XTAL2 (P0.3) pins skipped (P0SKIP = 0x0C to skip P0.2 and P0.3 for XTAL use). P1 XTAL1 XTAL2 3 4 5 6 7 0 1 2 0 0 0 0 0 0 0 0 VREF 2 SF Signals PIN I/O 0 1 0 0 0 P2 CNVSTR P0 3 4 5 6 7 0 0 0 0 0 0 0 1 2 3 0 0 0 4 5 6 7 TX0 RX0 SCK MISO MOSI NSS* SDA SCL CP0 Signals Unavailable CP0A CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 ECI T0 T1 P0SKIP[0:7] P1SKIP[0:7] P2SKIP[0:3] Port pin potentially available to peripheral SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must be manually configured to skip their corresponding port pins. *Note: NSS is only pinned out in 4-wire SPI mode. Note: P1.6,P1.7,P2.6,P2.7 only available on the C8051F310/1/2/3/4/5; P1SKIP[7:6] should always be set to 11b for the C8051F316/7 devices. Figure 13.3. Crossbar Priority Decoder with No Pins Skipped Rev. 1.8 131 C8051F310/1/2/3/4/5/6/7 P1 XTAL1 XTAL2 3 4 5 6 7 0 1 2 1 0 0 0 0 0 0 0 VREF 2 SF Signals PIN I/O 0 1 0 0 1 P2 CNVSTR P0 3 4 5 6 7 0 0 0 0 0 0 0 1 2 3 0 0 0 4 5 6 7 TX0 RX0 SCK MISO MOSI NSS* SDA SCL CP0 Signals Unavailable CP0A CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 ECI T0 T1 P0SKIP[0:7] P1SKIP[0:7] P2SKIP[0:3] Port pin potentially available to peripheral SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are enabled, the Crossbar must be manually configured to skip their corresponding port pins. *Note: NSS is only pinned out in 4-wire SPI mode. Note: P1.6,P1.7,P2.6,P2.7 only available on the C8051F310/1/2/3/4/5; P1SKIP[7:6] should always be set to 11b for the C8051F316/7 devices. Figure 13.4. Crossbar Priority Decoder with Crystal Pins Skipped Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and SCL); when the UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized functions have been assigned. Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the NSSMD1-NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be routed to a Port pin. 132 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 13.2. Port I/O Initialization Port I/O initialization consists of the following steps: Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode register (PnMDIN). Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output Mode register (PnMDOUT). Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP). Step 4. Assign Port pins to desired peripherals. Step 5. Enable the Crossbar (XBARE = ‘1’). All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its weak pullup, digital driver, and digital receiver are disabled. This process saves power and reduces noise on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this practice is not recommended. Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates a digital input, and a ‘0’ indicates an analog input. All pins default to digital inputs on reset. See SFR Definition 13.4 for the PnMDIN register details. The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pullup is enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is turned off on an output that is driving a ‘0’ to avoid unnecessary power dissipation. Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will determine the Port I/O pin-assignments based on the XBRn Register settings. The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers are disabled while the Crossbar is disabled. Rev. 1.8 133 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.1. XBR0: Port I/O Crossbar Register 0 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value CP1AE CP1E CP0AE CP0E SYSCKE SMB0E SPI0E URT0E 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xE1 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 134 CP1AE: Comparator1 Asynchronous Output Enable 0: Asynchronous CP1 unavailable at Port pin. 1: Asynchronous CP1 routed to Port pin. CP1E: Comparator1 Output Enable 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin. CP0AE: Comparator0 Asynchronous Output Enable 0: Asynchronous CP0 unavailable at Port pin. 1: Asynchronous CP0 routed to Port pin. CP0E: Comparator0 Output Enable 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. SYSCKE: /SYSCLK Output Enable 0: /SYSCLK unavailable at Port pin. 1: /SYSCLK output routed to Port pin. SMB0E: SMBus I/O Enable 0: SMBus I/O unavailable at Port pins. 1: SMBus I/O routed to Port pins. SPI0E: SPI I/O Enable 0: SPI I/O unavailable at Port pins. 1: SPI I/O routed to Port pins. URT0E: UART I/O Output Enable 0: UART I/O unavailable at Port pin. 1: UART TX0, RX0 routed to Port pins P0.4 and P0.5. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.2. XBR1: Port I/O Crossbar Register 1 R/W R/W R/W R/W R/W WEAKPUD XBARE T1E T0E ECIE Bit7 Bit6 Bit5 Bit4 Bit3 R/W R/W R/W Reset Value Bit0 SFR Address: PCA0ME Bit2 Bit1 00000000 0xE2 Bit7: WEAKPUD: Port I/O Weak Pullup Disable. 0: Weak Pullups enabled (except for Ports whose I/O are configured as analog input). 1: Weak Pullups disabled. Bit6: XBARE: Crossbar Enable. 0: Crossbar disabled. 1: Crossbar enabled. Bit5: T1E: T1 Enable 0: T1 unavailable at Port pin. 1: T1 routed to Port pin. Bit4: T0E: T0 Enable 0: T0 unavailable at Port pin. 1: T0 routed to Port pin. Bit3: ECIE: PCA0 External Counter Input Enable 0: ECI unavailable at Port pin. 1: ECI routed to Port pin. Bits2–0: PCA0ME: PCA Module I/O Enable Bits. 000: All PCA I/O unavailable at Port pins. 001: CEX0 routed to Port pin. 010: CEX0, CEX1 routed to Port pins. 011: CEX0, CEX1, CEX2 routed to Port pins. 100: CEX0, CEX1, CEX2, CEX3 routed to Port pins. 101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins. 13.3. General Purpose Port I/O Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for general purpose I/O. Ports3-0 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. The read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SET, when the destination is an individual bit in a Port SFR. For these instructions, the value of the register (not the pin) is read, modified, and written back to the SFR. Rev. 1.8 135 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.3. P0: Port0 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) 0x80 Bits7–0: P0.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0). Read - Always reads ‘1’ if selected as analog input in register P0MDIN. Directly reads Port pin when configured as digital input. 0: P0.n pin is logic low. 1: P0.n pin is logic high. SFR Definition 13.4. P0MDIN: Port0 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xF1 Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively). Port pins configured as analog inputs have their weak pullup, digital driver, and digital receiver disabled. 0: Corresponding P0.n pin is configured as an analog input. 1: Corresponding P0.n pin is not configured as an analog input. 136 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.5. P0MDOUT: Port0 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA4 Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0. 0: Corresponding P0.n Output is open-drain. 1: Corresponding P0.n Output is push-pull. Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless of the value of P0MDOUT. SFR Definition 13.6. P0SKIP: Port0 Skip R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xD4 Bits7–0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P0.n pin is not skipped by the Crossbar. 1: Corresponding P0.n pin is skipped by the Crossbar. Rev. 1.8 137 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.7. P1: Port1 R/W R/W R/W R/W R/W R/W R/W R/W Reset Value P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) 0x90 Bits7–0: P1.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0). Read - Always reads ‘1’ if selected as analog input in register P1MDIN. Directly reads Port pin when configured as digital input. 0: P1.n pin is logic low. 1: P1.n pin is logic high. Note: Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices. SFR Definition 13.8. P1MDIN: Port1 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xF2 Bits7–0: Analog Input Configuration Bits for P1.7-P1.0 (respectively). Port pins configured as analog inputs have their weak pullup, digital driver, and digital receiver disabled. 0: Corresponding P1.n pin is configured as an analog input. 1: Corresponding P1.n pin is not configured as an analog input. Note: 138 Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.9. P1MDOUT: Port1 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA5 Bits7–0: Output Configuration Bits for P1.7-P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0. 0: Corresponding P1.n Output is open-drain. 1: Corresponding P1.n Output is push-pull. Note: Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices. SFR Definition 13.10. P1SKIP: Port1 Skip R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value ‘F310/1/2/3/4/5: 00000000 ‘F316/7: 11000000 SFR Address: 0xD5 Bits7–0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P1.n pin is not skipped by the Crossbar. 1: Corresponding P1.n pin is skipped by the Crossbar. Note: Only P1.0–P1.5 are associated with Port pins on the C8051F316/7 devices. Hence, in C8051F316/7 devices, user code writing to this SFR should always set P1SKIP[7:6] = 11b so that those two pins are skipped by the crossbar decoder. Rev. 1.8 139 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.11. P2: Port2 R/W R/W R/W R/W R/W R/W R/W R/W P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Reset Value 0xA0 Bits7–0: P2.[7:0] Write - Output appears on I/O pins per Crossbar Registers. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0). Read - Always reads ‘1’ if selected as analog input in register P2MDIN. Directly reads Port pin when configured as digital input. 0: P2.n pin is logic low. 1: P2.n pin is logic high. Note: Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices. SFR Definition 13.12. P2MDIN: Port2 Input Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xF3 Bits7–0: Analog Input Configuration Bits for P2.7–P2.0 (respectively). Port pins configured as analog inputs have their weak pullup, digital driver, and digital receiver disabled. 0: Corresponding P2.n pin is configured as an analog input. 1: Corresponding P2.n pin is not configured as an analog input. Note: 140 Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.13. P2MDOUT: Port2 Output Mode R/W R/W R/W R/W R/W R/W R/W R/W Reset Value Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 00000000 0xA6 Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in register P2MDIN is logic 0. 0: Corresponding P2.n Output is open-drain. 1: Corresponding P2.n Output is push-pull. Note: Only P2.0–P2.5 are associated with Port pins on the C8051F316/7 devices. SFR Definition 13.14. P2SKIP: Port2 Skip R/W R/W R/W R/W - - - - Bit7 Bit6 Bit5 Bit4 R/W R/W R/W R/W Reset Value 00000000 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xD6 Bits7–0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits. These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar. 0: Corresponding P2.n pin is not skipped by the Crossbar. 1: Corresponding P2.n pin is skipped by the Crossbar. Note: Only P2.0–P2.3 are associated with the Crossbar. Rev. 1.8 141 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.15. P3: Port3 R/W R/W R/W R/W R/W R/W R/W R/W P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0 11111111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: (bit addressable) Reset Value 0xB0 Bits7–0: P3.[7:0] Write - Output appears on I/O pins. 0: Logic Low Output. 1: Logic High Output (high impedance if corresponding P3MDOUT.n bit = 0). Read - Always reads ‘1’ if selected as analog input in register P3MDIN. Directly reads Port pin when configured as digital input. 0: P3.n pin is logic low. 1: P3.n pin is logic high. Note: Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a Port pin on C8051F311/3/5/6/7 devices. SFR Definition 13.16. P3MDIN: Port3 Input Mode R/W R/W R/W - - - Bit7 Bit6 Bit5 R/W R/W R/W R/W R/W Reset Value Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 11111111 0xF4 Bits7–5: UNUSED. Read = 000b; Write = don’t care. Bits4–0: Input Configuration Bits for P3.4–P3.0 (respectively). Port pins configured as analog inputs have their weak pullup, digital driver, and digital receiver disabled. 0: Corresponding P3.n pin is configured as an analog input. 1: Corresponding P3.n pin is not configured as an analog input. Note: 142 Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a Port pin on C8051F311/3/5/6/7 devices. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 13.17. P3MDOUT: Port3 Output Mode R/W R/W R/W - - - Bit7 Bit6 Bit5 R/W R/W R/W R/W R/W Reset Value 00000000 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA7 Bits7–5: UNUSED. Read = 000b; Write - don’t care. Bits4–0: Output Configuration Bits for P3.4–P3.0 (respectively): ignored if corresponding bit in register P3MDIN is logic 0. 0: Corresponding P3.n Output is open-drain. 1: Corresponding P3.n Output is push-pull. Note: Only P3.0–P3.4 are associated with Port pins on C8051F310/2/4 devices; Only P3.0 is associated with a Port pin on C8051F311/3/5/6/7 devices. Table 13.1. Port I/O DC Electrical Characteristics VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified Parameters Conditions Min IOH = –3 mA, Port I/O push-pull VDD – 0.7 Output High Voltage Output Low Voltage Max VDD – 0.1 — — IOH = –10 mA, Port I/O push-pull IOL = 8.5 mA — VDD – 0.8 — — — 0.6 IOL = 10 µA — — 0.1 IOL = 25 mA — 1.0 — Weak Pullup Off 2.0 — — — — — — 0.8 ±1 Weak Pullup On, VIN = 0 V — 25 40 Rev. 1.8 Units — IOH = –10 µA, Port I/O push-pull Input High Voltage Input Low Voltage Input Leakage Current Typ — V V V V µA 143 C8051F310/1/2/3/4/5/6/7 NOTES: 144 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14. SMBus The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to the interface by the system controller are byte oriented with the SMBus interface autonomously controlling the serial transfer of the data. Data can be transferred at up to 1/10th of the system clock as a master or slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus: SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data register, used for both transmitting and receiving SMBus data and slave addresses. SMB0CN MT S S A A A S A X T T CRC 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 OOT S S L E E 1 0 D 00 T0 Overflow 01 T1 Overflow 10 TMR2H Overflow 11 TMR2L Overflow SMBUS CONTROL LOGIC Interrupt Request Arbitration SCL Synchronization SCL Generation (Master Mode) SDA Control Data Path IRQ Generation Control SCL FILTER SCL Control C R O S S B A R N SDA Control SMB0DAT 7 6 5 4 3 2 1 0 Port I/O SDA FILTER N Figure 14.1. SMBus Block Diagram Rev. 1.8 145 C8051F310/1/2/3/4/5/6/7 14.1. Supporting Documents It is assumed the reader is familiar with or has access to the following supporting documents: • • • The I2C-Bus and How to Use It (including specifications), Philips Semiconductor. The I2C-Bus Specification—Version 2.0, Philips Semiconductor. System Management Bus Specification—Version 1.1, SBS Implementers Forum. 14.2. SMBus Configuration Figure 14.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus not exceed 300 ns and 1000 ns, respectively. VDD = 5 V VDD = 3 V VDD = 5 V VDD = 3 V Master Device Slave Device 1 Slave Device 2 SDA SCL Figure 14.2. Typical SMBus Configuration 14.3. SMBus Operation Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ). The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitration. Note that it is not necessary to specify one device as the Master in a system; any device 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. Each byte that is received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see Figure 14.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL. 146 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 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 14.3 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 14.3. SMBus Transaction 14.3.1. Arbitration A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section “14.3.4. SCL High (SMBus Free) Timeout” on page 148). 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. Rev. 1.8 147 C8051F310/1/2/3/4/5/6/7 14.3.2. Clock Low Extension SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line LOW to extend the clock low period, effectively decreasing the serial clock frequency. 14.3.3. SCL Low Timeout If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the 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. 14.3.4. SCL High (SMBus Free) Timeout The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a Master START, the START will be generated following this timeout. Note that a clock source is required for free timeout detection, even in a slave-only implementation. 148 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14.4. Using the SMBus The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides the following application-independent features: • • • • • • • Byte-wise serial data transfers Clock signal generation on SCL (Master Mode only) and SDA data synchronization Timeout/bus error recognition, as defined by the SMB0CF configuration register START/STOP timing, detection, and generation Bus arbitration Interrupt generation Status information SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting, this interrupt is generated after the ACK cycle so that software may read the received ACK value; when receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing ACK value. See Section “14.5. SMBus Transfer Modes” on page 157 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 “14.4.2. SMB0CN Control Register” on page 153; Table 14.4 provides a quick SMB0CN decoding reference. SMBus configuration options include: • • • • Timeout detection (SCL Low Timeout and/or Bus Free Timeout) SDA setup and hold time extensions Slave event enable/disable Clock source selection These options are selected in the SMB0CF register, as described in Section “14.4.1. SMBus Configuration Register” on page 150. Rev. 1.8 149 C8051F310/1/2/3/4/5/6/7 14.4.1. SMBus Configuration Register The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes, select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however, the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of the current transfer). Table 14.1. SMBus Clock Source Selection SMBCS1 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 14.1. Note that the selected clock source may be shared by other peripherals so long as the timer is left running at all times. For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer configuration is covered in Section “17. Timers” on page 187. Equation 14.1. Minimum SCL High and Low Times 1 T HighMin = T LowMin = ---------------------------------------------f ClockSourceOverflow The selected clock source should be configured to establish the minimum SCL High and Low times as per Equation 14.1. When the interface is operating as a master (and SCL is not driven or extended by any other devices on the bus), the typical SMBus bit rate is approximated by Equation 14.2. Equation 14.2. Typical SMBus Bit Rate f ClockSourceOverflow BitRate = ---------------------------------------------3 150 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Figure 14.4 shows the typical SCL generation described by Equation 14.2. Notice that THIGH is typically twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be extended low by slower slave devices, or driven low by contending master devices). The bit rate when operating as a master will never exceed the limits defined by equation Equation 14.1. Timer Source Overflows SCL TLow THigh SCL High Timeout Figure 14.4. Typical SMBus SCL Generation Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high. The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 14.2 shows the 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 14.2. Minimum SDA Setup and Hold Times EXTHOLD Minimum SDA Setup Time Tlow – 4 system clocks Minimum SDA Hold Time 0 OR 3 system clocks 1 1 system clock + s/w delay* 11 system clocks 12 system clocks *Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w delay occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w delay is zero. With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low timeouts (see Section “14.3.3. SCL Low Timeout” on page 148). 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 14.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an interrupt will be generated, and STO will be set). Rev. 1.8 151 C8051F310/1/2/3/4/5/6/7 SFR Definition 14.1. SMB0CF: SMBus Clock/Configuration R/W R/W R ENSMB INH BUSY Bit7 Bit6 Bit5 R/W R/W R/W R/W EXTHOLD SMBTOE SMBFTE SMBCS1 Bit4 Bit3 Bit2 Bit1 R/W Reset Value SMBCS0 00000000 Bit0 SFR Address: 0xC1 Bit7: ENSMB: SMBus Enable. This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins. 0: SMBus interface disabled. 1: SMBus interface enabled. Bit6: INH: SMBus Slave Inhibit. When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are not affected. 0: SMBus Slave Mode enabled. 1: SMBus Slave Mode inhibited. Bit5: BUSY: SMBus Busy Indicator. This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0 when a STOP or free-timeout is sensed. Bit4: EXTHOLD: SMBus Setup and Hold Time Extension Enable. This bit controls the SDA setup and hold times according to Table 14.2. 0: SDA Extended Setup and Hold Times disabled. 1: SDA Extended Setup and Hold Times enabled. Bit3: SMBTOE: SMBus SCL Timeout Detection Enable. This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low. If Timer 3 is configured in split mode (T3SPLIT is set), only the high byte of Timer 3 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. Bit2: SMBFTE: SMBus Free Timeout Detection Enable. When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. Bits1–0: SMBCS1-SMBCS0: SMBus Clock Source Selection. These two bits select the SMBus clock source, which is used to generate the SMBus bit rate. The selected device should be configured according to Equation 14.1. SMBCS1 0 0 1 1 152 SMBCS0 0 1 0 1 SMBus Clock Source Timer 0 Overflow Timer 1 Overflow Timer 2 High Byte Overflow Timer 2 Low Byte Overflow Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14.4.2. SMB0CN Control Register SMB0CN is used to control the interface and to provide status information (see SFR Definition 14.2). The higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive modes, respectively. STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO while in Master Mode will cause the interface to generate a STOP and end the current transfer after the next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be generated. As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be ignored until the next START is detected. The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared. The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or when an arbitration is lost; see Table 14.3 for more details. Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and the bus is stalled until software clears SI. Table 14.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 14.4 for SMBus status decoding using the SMB0CN register. Rev. 1.8 153 C8051F310/1/2/3/4/5/6/7 SFR Definition 14.2. SMB0CN: SMBus Control R R MASTER TXMODE Bit7 Bit6 R/W R/W STA STO Bit5 Bit4 R R ACKRQ ARBLOST Bit3 Bit2 R/W R/W Reset Value ACK SI 00000000 Bit1 Bit0 Bit Addressable SFR Address: 0xC0 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 154 MASTER: SMBus Master/Slave Indicator. This read-only bit indicates when the SMBus is operating as a master. 0: SMBus operating in Slave Mode. 1: SMBus operating in Master Mode. TXMODE: SMBus Transmit Mode Indicator. This read-only bit indicates when the SMBus is operating as a transmitter. 0: SMBus in Receiver Mode. 1: SMBus in Transmitter Mode. STA: SMBus Start Flag. Write: 0: No Start generated. 1: When operating as a master, a START condition is transmitted if the bus is free (If the bus is not free, the START is transmitted after a STOP is received or a timeout is detected). If STA is set by software as an active Master, a repeated START will be generated after the next ACK cycle. Read: 0: No Start or repeated Start detected. 1: Start or repeated Start detected. STO: SMBus Stop Flag. Write: 0: No STOP condition is transmitted. 1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA and STO are set, a STOP condition is transmitted followed by a START condition. Read: 0: No Stop condition detected. 1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode). ACKRQ: SMBus Acknowledge Request This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK bit to be written with the correct ACK response value. ARBLOST: SMBus Arbitration Lost Indicator. This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a transmitter. A lost arbitration while a slave indicates a bus error condition. ACK: SMBus Acknowledge Flag. This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted. 0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). 1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in Receiver Mode). SI: SMBus Interrupt Flag. This bit is set by hardware under the conditions listed in Table 14.3. SI must be cleared by software. While SI is set, SCL is held low and the SMBus is stalled. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 Table 14.3. Sources for Hardware Changes to SMB0CN Bit MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI Set by Hardware When... • A START is generated. • START is generated. • SMB0DAT is written before the start of an SMBus frame. • A START followed by an address byte is received. • A STOP is detected while addressed as a slave. • Arbitration is lost due to a detected STOP. • A byte has been received and an ACK response value is needed. • A repeated START is detected as a MASTER when STA is low (unwanted repeated START). • SCL is sensed low while attempting to generate a STOP or repeated START condition. • SDA is sensed low while transmitting a ‘1’ (excluding ACK bits). • The incoming ACK value is low (ACKNOWLEDGE). • A START has been generated. • Lost arbitration. • A byte has been transmitted and an ACK/NACK received. • A byte has been received. • A START or repeated START followed by a slave address + R/W has been received. • A STOP has been received. Rev. 1.8 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. 155 C8051F310/1/2/3/4/5/6/7 14.4.3. Data Register The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software may safely read or write to the data register when the SI flag is set. Software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0, as the interface may be in the process of shifting a byte of data into or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in SMB0DAT. SFR Definition 14.3. SMB0DAT: SMBus Data R/W R/W R/W R/W R/W R/W R/W R/W Reset Value 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xC2 Bits7–0: SMB0DAT: SMBus Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long as the SI flag is set. When the SI flag is not set, the system may be in the process of shifting data in/out and the CPU should not attempt to access this register. 156 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14.5. SMBus Transfer Modes The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter. 14.5.1. Master Transmitter Mode Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt. Figure 14.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. S SLA W Interrupt A Interrupt Data Byte A Data Byte Interrupt A P Interrupt S = START P = STOP A = ACK W = WRITE SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 14.5. Typical Master Transmitter Sequence Rev. 1.8 157 C8051F310/1/2/3/4/5/6/7 14.5.2. Master Receiver Mode Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit generates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written while an active Master Receiver. Figure 14.6 shows a typical Master Receiver sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode. S SLA R Interrupt A Interrupt Data Byte A Interrupt Data Byte N Interrupt S = START P = STOP A = ACK N = NACK R = READ SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 14.6. Typical Master Receiver Sequence 158 Rev. 1.8 P C8051F310/1/2/3/4/5/6/7 14.5.3. Slave Receiver Mode Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit (WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 14.7 shows a typical Slave Receiver sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode. Interrupt S SLA W A Interrupt Data Byte A Interrupt Data Byte A P Interrupt S = START P = STOP A = ACK W = WRITE SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 14.7. Typical Slave Receiver Sequence Rev. 1.8 159 C8051F310/1/2/3/4/5/6/7 14.5.4. Slave Transmitter Mode Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a slave address and direction bit (READ in this case) is received. Upon entering Slave Transmitter Mode, an interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 14.8 shows a typical Slave Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. Interrupt S SLA R A Interrupt Data Byte A Data Byte Interrupt N P Interrupt S = START P = STOP N = NACK R = READ SLA = Slave Address Received by SMBus Interface Transmitted by SMBus Interface Figure 14.8. Typical Slave Transmitter Sequence 160 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 14.6. SMBus Status Decoding The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the shown response options are only the typical responses; application-specific procedures are allowed as long as they conform to the SMBus specification. Highlighted responses are allowed but do not conform to the SMBus specification. Table 14.4. SMBus Status Decoding Values Written ARBLOST ACK 0 X 0 0 1100 0 1000 1 0 0 A master START was generated. A master data or address byte 0 was transmitted; NACK received. Load slave address + R/W into SMB0DAT. Set STA to restart transfer. Abort transfer. Load next data byte into SMB0DAT. End transfer with STOP. A master data or address byte End transfer with STOP and start another transfer. 1 was transmitted; ACK received. Send repeated START. Switch to Master Receiver Mode (clear SI without writing new data to SMB0DAT). Acknowledge received byte; Read SMB0DAT. Send NACK to indicate last byte, and send STOP. Send NACK to indicate last byte, and send STOP followed by START. Send ACK followed by repeated A master data byte was START. X received; ACK requested. Send NACK to indicate last byte, and send repeated START. Send ACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). Send NACK and switch to Master Transmitter Mode (write to SMB0DAT before clearing SI). Rev. 1.8 ACK ACKRQ 0 Typical Response Options STO Status Vector 1110 Current SMbus State STA Master Receiver Master Transmitter Mode Values Read 0 0 X 1 0 X 0 1 X 0 0 X 0 1 X 1 1 X 1 0 X 0 0 X 0 0 1 0 1 0 1 1 0 1 0 1 1 0 0 0 0 1 0 0 0 161 C8051F310/1/2/3/4/5/6/7 Table 14.4. SMBus Status Decoding (Continued) Values Written 0 0 1 0 X 1 0 0010 Slave Receiver 1 0010 0001 1 X A slave address was received; ACK requested. Lost arbitration as master; X slave address received; ACK requested. 1 1 1 0 0 0 1 X 0 A slave byte was received; X ACK requested. 1 1 1 X Lost arbitration while attempting a repeated START. 0 0000 162 A slave byte was transmitted; NACK received. A slave byte was transmitted; 1 ACK received. A Slave byte was transmitted; X error detected. A STOP was detected while X an addressed Slave Transmitter. 0 Lost arbitration while attempting a STOP. A STOP was detected while X an addressed slave receiver. X X Lost arbitration due to a detected STOP. Lost arbitration while transmitting a data byte as master. No action required (expecting STOP condition). Load SMB0DAT with next data byte to transmit. No action required (expecting Master to end transfer). No action required (transfer complete). Acknowledge received address. Do not acknowledge received address. Acknowledge received address. Do not acknowledge received address. Reschedule failed transfer; do not acknowledge received address. Abort failed transfer. Reschedule failed transfer. No action required (transfer complete/aborted). No action required (transfer complete). Abort transfer. Reschedule failed transfer. Acknowledge received byte; Read SMB0DAT. Do not acknowledge received byte. Abort failed transfer. Reschedule failed transfer. Rev. 1.8 ACK 0 Typical Response Options STO 0 ACK 0 Current SMbus State STA 0101 ARBLOST Status Vector 0100 ACKRQ Slave Transmitter Mode Values Read 0 0 X 0 0 X 0 0 X 0 0 X 0 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 X X 0 0 0 0 0 X 0 1 0 0 X X 0 0 1 0 0 0 0 1 0 0 0 0 C8051F310/1/2/3/4/5/6/7 15. UART0 UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART. Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details in Section “15.1. Enhanced Baud Rate Generation” on page 164). 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 15.1. UART0 Block Diagram Rev. 1.8 163 C8051F310/1/2/3/4/5/6/7 15.1. Enhanced Baud Rate Generation The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 15.2), which is not 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 15.2. UART0 Baud Rate Logic Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “17.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload” on page 189). 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 15.1. Equation 15.1. UART0 Baud Rate T1 CLK 1 UartBaudRate = -------------------------------  -- 256 – T1H  2 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 “17. Timers” on page 187. A quick reference for typical baud rates and system clock frequencies is given in Table 15.1 through Table 15.6. Note that the internal oscillator may still generate the system clock when the external oscillator is driving Timer 1. 164 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 15.2. Operational Modes UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown in Figure 15.3. TX RS-232 LEVEL XLTR RS-232 RX C8051Fxxx OR TX TX RX RX MCU C8051Fxxx Figure 15.3. UART Interconnect Diagram 15.2.1. 8-Bit UART 8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted LSB first from the 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 15.4. 8-Bit UART Timing Diagram Rev. 1.8 165 C8051F310/1/2/3/4/5/6/7 15.2.2. 9-Bit UART 9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a 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 BIT TIMES BIT SAMPLING Figure 15.5. 9-Bit UART Timing Diagram 166 Rev. 1.8 D7 D8 STOP BIT C8051F310/1/2/3/4/5/6/7 15.3. Multiprocessor Communications 9-Bit UART mode supports multiprocessor communication between a master processor and one or more slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0. Setting the MCE0 bit (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). Master Device Slave Device Slave Device Slave Device V+ RX TX RX TX RX TX RX TX Figure 15.6. UART Multi-Processor Mode Interconnect Diagram Rev. 1.8 167 C8051F310/1/2/3/4/5/6/7 SFR Definition 15.1. SCON0: Serial Port 0 Control R/W R S0MODE Bit7 Bit6 R/W R/W R/W R/W R/W R/W Reset Value MCE0 REN0 TB80 RB80 TI0 RI0 01000000 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit Addressable SFR Address: 0x98 Bit7: Bit6: Bit5: Bit4: Bit3: Bit2: Bit1: Bit0: 168 S0MODE: Serial Port 0 Operation Mode. This bit selects the UART0 Operation Mode. 0: 8-bit UART with Variable Baud Rate. 1: 9-bit UART with Variable Baud Rate. UNUSED. Read = 1b. Write = don’t care. MCE0: Multiprocessor Communication Enable. The function of this bit is dependent on the Serial Port 0 Operation Mode. S0MODE = 0: Checks for valid stop bit. 0: Logic level of stop bit is ignored. 1: RI0 will only be activated if stop bit is logic level 1. S0MODE = 1: Multiprocessor Communications Enable. 0: Logic level of ninth bit is ignored. 1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1. REN0: Receive Enable. This bit enables/disables the UART receiver. 0: UART0 reception disabled. 1: UART0 reception enabled. TB80: Ninth Transmission Bit. The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It is not used in 8-bit UART Mode. Set or cleared by software as required. RB80: Ninth Receive Bit. RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th data bit in Mode 1. TI0: Transmit Interrupt Flag. Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. RI0: Receive Interrupt Flag. Set to ‘1’ by hardware when a byte of data has been received by UART0 (set at the STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 15.2. SBUF0: Serial (UART0) Port Data Buffer R/W R/W R/W R/W R/W R/W R/W R/W Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Reset Value 00000000 SFR Address: 0x99 Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB–LSB) This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch. Rev. 1.8 169 C8051F310/1/2/3/4/5/6/7 SYSCLK from Internal Osc. Table 15.1. Timer Settings for Standard Baud Rates Using the Internal Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 Frequency: 24.5 MHz Oscilla- Timer Clock SCA1-SCA0 T1M* Timer 1 tor Divide Source (pre-scale Reload Value Factor select)* (hex) –0.32% 106 SYSCLK XX 1 0xCB –0.32% 212 SYSCLK XX 1 0x96 0.15% 426 SYSCLK XX 1 0x2B –0.32% 848 SYSCLK / 4 01 0 0x96 0.15% 1704 SYSCLK / 12 00 0 0xB9 –0.32% 2544 SYSCLK / 12 00 0 0x96 –0.32% 10176 SYSCLK / 48 10 0 0x96 0.15% 20448 SYSCLK / 48 10 0 0x2B X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. Baud Rate % Error SYSCLK from SYSCLK from Internal Osc. External Osc. Table 15.2. Timer Settings for Standard Baud Rates Using an External 25 MHz Oscillator Target Baud Rate (bps) Baud Rate % Error 230400 115200 57600 28800 14400 9600 2400 1200 57600 28800 14400 –0.47% 0.45% –0.01% 0.45% –0.01% 0.15% 0.45% –0.01% –0.47% –0.47% 0.45% 9600 0.15% Frequency: 25.0 MHz Oscilla- Timer Clock SCA1-SCA0 tor Divide Source (pre-scale Factor select)* 108 SYSCLK XX 218 SYSCLK XX 434 SYSCLK XX 872 SYSCLK / 4 01 1736 SYSCLK / 4 01 2608 EXTCLK / 8 11 10464 SYSCLK / 48 10 20832 SYSCLK / 48 10 432 EXTCLK / 8 11 864 EXTCLK / 8 11 1744 EXTCLK / 8 11 2608 EXTCLK / 8 11 T1M* Timer 1 Reload Value (hex) 1 1 1 0 0 0 0 0 0 0 0 0xCA 0x93 0x27 0x93 0x27 0x5D 0x93 0x27 0xE5 0xCA 0x93 0 0x5D X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. 170 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SYSCLK from Internal Osc. SYSCLK from External Osc. Table 15.3. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 22.1184 MHz Oscilla- Timer Clock SCA1-SCA0 T1M* Timer 1 tor Divide Source (pre-scale Reload Value Factor select)* (hex) 0.00% 96 SYSCLK XX 1 0xD0 0.00% 192 SYSCLK XX 1 0xA0 0.00% 384 SYSCLK XX 1 0x40 0.00% 768 SYSCLK / 12 00 0 0xE0 0.00% 1536 SYSCLK / 12 00 0 0xC0 0.00% 2304 SYSCLK / 12 00 0 0xA0 0.00% 9216 SYSCLK / 48 10 0 0xA0 0.00% 18432 SYSCLK / 48 10 0 0x40 0.00% 96 EXTCLK / 8 11 0 0xFA 0.00% 192 EXTCLK / 8 11 0 0xF4 0.00% 384 EXTCLK / 8 11 0 0xE8 0.00% 768 EXTCLK / 8 11 0 0xD0 0.00% 1536 EXTCLK / 8 11 0 0xA0 0.00% 2304 EXTCLK / 8 11 0 0x70 X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. Baud Rate % Error SYSCLK from Internal Osc. SYSCLK from External Osc. Table 15.4. Timer Settings for Standard Baud Rates Using an External 18.432 MHz Oscillator Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 18.432 MHz Oscilla- Timer Clock SCA1-SCA0 T1M* Timer 1 tor Divide Source (pre-scale Reload Factor select)* Value (hex) 0.00% 80 SYSCLK XX 1 0xD8 0.00% 160 SYSCLK XX 1 0xB0 0.00% 320 SYSCLK XX 1 0x60 0.00% 640 SYSCLK / 4 01 0 0xB0 0.00% 1280 SYSCLK / 4 01 0 0x60 0.00% 1920 SYSCLK / 12 00 0 0xB0 0.00% 7680 SYSCLK / 48 10 0 0xB0 0.00% 15360 SYSCLK / 48 10 0 0x60 0.00% 80 EXTCLK / 8 11 0 0xFB 0.00% 160 EXTCLK / 8 11 0 0xF6 0.00% 320 EXTCLK / 8 11 0 0xEC 0.00% 640 EXTCLK / 8 11 0 0xD8 0.00% 1280 EXTCLK / 8 11 0 0xB0 0.00% 1920 EXTCLK / 8 11 0 0x88 X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. Baud Rate % Error Rev. 1.8 171 C8051F310/1/2/3/4/5/6/7 SYSCLK from Internal Osc. SYSCLK from External Osc. Table 15.5. Timer Settings for Standard Baud Rates Using an External 11.0592 MHz Oscillator Frequency: 11.0592 MHz Target Baud Rate Oscilla- Timer Clock SCA1-SCA0 T1M* Timer 1 Baud Rate % Error tor Divide Source (pre-scale Reload Value (bps) Factor select)* (hex) 230400 0.00% 48 SYSCLK XX 1 0xE8 115200 0.00% 96 SYSCLK XX 1 0xD0 57600 0.00% 192 SYSCLK XX 1 0xA0 28800 0.00% 384 SYSCLK XX 1 0x40 14400 0.00% 768 SYSCLK / 12 00 0 0xE0 9600 0.00% 1152 SYSCLK / 12 00 0 0xD0 2400 0.00% 4608 SYSCLK / 12 00 0 0x40 1200 0.00% 9216 SYSCLK / 48 10 0 0xA0 230400 0.00% 48 EXTCLK / 8 11 0 0xFD 115200 0.00% 96 EXTCLK / 8 11 0 0xFA 57600 0.00% 192 EXTCLK / 8 11 0 0xF4 28800 0.00% 384 EXTCLK / 8 11 0 0xE8 14400 0.00% 768 EXTCLK / 8 11 0 0xD0 9600 0.00% 1152 EXTCLK / 8 11 0 0xB8 X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. SYSCLK from Internal Osc. SYSCLK from External Osc. Table 15.6. Timer Settings for Standard Baud Rates Using an External 3.6864 MHz Oscillator 172 Target Baud Rate (bps) 230400 115200 57600 28800 14400 9600 2400 1200 230400 115200 57600 28800 14400 9600 Frequency: 3.6864 MHz Oscilla- Timer Clock SCA1-SCA0 T1M* Timer 1 tor Divide Source (pre-scale Reload Factor select)* Value (hex) 16 SYSCLK XX 1 0xF8 32 SYSCLK XX 1 0xF0 64 SYSCLK XX 1 0xE0 128 SYSCLK XX 1 0xC0 256 SYSCLK XX 1 0x80 384 SYSCLK XX 1 0x40 1536 SYSCLK / 12 00 0 0xC0 3072 SYSCLK / 12 00 0 0x80 16 EXTCLK / 8 11 0 0xFF 32 EXTCLK / 8 11 0 0xFE 64 EXTCLK / 8 11 0 0xFC 128 EXTCLK / 8 11 0 0xF8 256 EXTCLK / 8 11 0 0xF0 384 EXTCLK / 8 11 0 0xE8 X = Don’t care *Note: SCA1–SCA0 and T1M bit definitions can be found in Section 17.1. Baud Rate% Error 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% Rev. 1.8 C8051F310/1/2/3/4/5/6/7 16. Enhanced Serial Peripheral Interface (SPI0) The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode. SFR Bus SYSCLK SPI0CN SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN SPI0CFG SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 SPI0CKR Clock Divide Logic SPI CONTROL LOGIC Data Path Control SPI IRQ Pin Interface Control MOSI Tx Data SPI0DAT 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 16.1. SPI Block Diagram Rev. 1.8 173 C8051F310/1/2/3/4/5/6/7 16.1. Signal Descriptions The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below. 16.1.1. Master Out, Slave In (MOSI) The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire mode. 16.1.2. Master In, Slave Out (MISO) The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device. It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register. 16.1.3. Serial Clock (SCK) The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is not selected (NSS = 1) in 4-wire slave mode. 16.1.4. Slave Select (NSS) The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0 bits in the SPI0CN register. There are three possible modes that can be selected with these bits: • • • NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-topoint communication between a master and one slave. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple master devices can be used on the same SPI bus. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration should only be used when operating SPI0 as a master device. See Figure 16.2, Figure 16.3, and Figure 16.4 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 “13. Port Input/Output” on page 129 for general purpose port I/O and crossbar information. 174 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 16.2. SPI0 Master Mode Operation A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0 must be manually re-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins. Figure 16.2 shows a connection diagram between two master devices in multiple-master mode. 3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 16.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 16.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices. Rev. 1.8 175 C8051F310/1/2/3/4/5/6/7 Master Device 1 NSS GPIO MISO MISO MOSI MOSI SCK SCK GPIO NSS Master Device 2 Figure 16.2. Multiple-Master Mode Connection Diagram Master Device MISO MISO MOSI MOSI SCK SCK Slave Device Figure 16.3. 3-Wire Single Master and Slave Mode Connection Diagram Master Device GPIO MISO MISO MOSI MOSI SCK SCK NSS NSS MISO MOSI Slave Device Slave Device SCK NSS Figure 16.4. 4-Wire Single Master and Slave Mode Connection Diagram 176 Rev. 1.8 C8051F310/1/2/3/4/5/6/7 16.3. SPI0 Slave Mode Operation When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are doublebuffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will 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, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0, and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer. Figure 16.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master device. 3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and reenabling SPI0 with the SPIEN bit. Figure 16.3 shows a connection diagram between a slave device in 3wire slave mode and a master device. 16.4. SPI0 Interrupt Sources When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: Note that all of the following bits must be cleared by software. 1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can occur in all SPI0 modes. 2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0 modes. 3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost. Rev. 1.8 177 C8051F310/1/2/3/4/5/6/7 16.5. Serial Clock Timing Four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between 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 SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The clock and data line relationships for master mode are shown in Figure 16.5. For slave mode, the clock and data relationships are shown in Figure 16.6 and Figure 16.7. 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 SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 16.3 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 16.5. Master Mode Data/Clock Timing 178 Rev. 1.8 Bit 1 Bit 0 C8051F310/1/2/3/4/5/6/7 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 16.6. 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 16.7. Slave Mode Data/Clock Timing (CKPHA = 1) Rev. 1.8 179 C8051F310/1/2/3/4/5/6/7 16.6. SPI Special Function Registers SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate Register. The four special function registers related to the operation of the SPI0 Bus are described in the following register definitions. SFR Definition 16.1. SPI0CFG: SPI0 Configuration R R/W R/W R/W R R R R Reset Value SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT 00000111 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA1 Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: *Note: 180 SPIBSY: SPI Busy (read only). This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode). MSTEN: Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. CKPHA: SPI0 Clock Phase. This bit controls the SPI0 clock phase. 0: Data centered on first edge of SCK period.* 1: Data centered on second edge of SCK period.* CKPOL: SPI0 Clock Polarity. This bit controls the SPI0 clock polarity. 0: SCK line low in idle state. 1: SCK line high in idle state. SLVSEL: Slave Selected Flag (read only). This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the instantaneous value at the NSS pin, but rather a de-glitched version of the pin input. NSSIN: NSS Instantaneous Pin Input (read only). This bit mimics the instantaneous value that is present on the NSS port pin at the time that the register is read. This input is not de-glitched. SRMT: Shift Register Empty (Valid in Slave Mode, read only). This bit will be set to logic 1 when all data has been transferred in/out of the shift register, and there is no new information available to read from the transmit buffer or write to the receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from the transmit buffer or by a transition on SCK. NOTE: SRMT = 1 when in Master Mode. RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only). This bit will be set to logic 1 when the receive buffer has been read and contains no new information. If there is new information available in the receive buffer that has not been read, this bit will return to logic 0. NOTE: RXBMT = 1 when in Master Mode. 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 16.1 for timing parameters. Rev. 1.8 C8051F310/1/2/3/4/5/6/7 SFR Definition 16.2. SPI0CN: SPI0 Control R/W R/W R/W SPIF WCOL MODF Bit7 Bit6 Bit5 R/W R/W R/W RXOVRN NSSMD1 NSSMD0 Bit4 Bit3 Bit2 R R/W Reset Value TXBMT SPIEN 00000110 Bit1 Bit0 Bit Addressable SFR Address: 0xF8 Bit 7: SPIF: SPI0 Interrupt Flag. This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled, setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not automatically cleared by hardware. It must be cleared by software. Bit 6: WCOL: Write Collision Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to the SPI0 data register was attempted while a data transfer was in progress. It must be cleared by software. Bit 5: MODF: Mode Fault Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software. Bit 4: RXOVRN: Receive Overrun Flag (Slave Mode only). This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must be cleared by software. Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode. Selects between the following NSS operation modes: (See Section “16.2. SPI0 Master Mode Operation” on page 175 and Section “16.3. SPI0 Slave Mode Operation” on page 177). 00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin. 01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device. 1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will assume the value of NSSMD0. Bit 1: TXBMT: Transmit Buffer Empty. This bit will be set to logic 0 when new data has been written to the transmit buffer. When data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer. Bit 0: SPIEN: SPI0 Enable. This bit enables/disables the SPI. 0: SPI disabled. 1: SPI enabled. Rev. 1.8 181 C8051F310/1/2/3/4/5/6/7 SFR Definition 16.3. SPI0CKR: SPI0 Clock Rate R/W R/W R/W R/W R/W R/W R/W R/W Reset Value SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 00000000 Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address: 0xA2 Bits 7–0: SCR7–SCR0: SPI0 Clock Rate. These bits determine the frequency of the SCK output when the SPI0 module is configured for master mode operation. The SCK clock frequency is a divided version of the system clock, and is given in the following equation, where SYSCLK is the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR register. SYSCLK f SCK = ------------------------------------------------2   SPI0CKR + 1  for 0