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THE COMPANY SHALL NOT, ;IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR ;CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER. ; ******************************************************************* ; 00031R1-1.asm ; This file is demonstration firmware for the MCP9800 Temperature ; sensor PICtail daughter board. It is targeted to run on a PIC16F684 ; installed in the evaluation socket of a PICkit, with the MCP9800 ; PICtail daughter board installed in connector J3 on the PICkit. ; This firmware will program the MCP9800 on the daughter board as ; directed by constants in the firmware and the potentiometer on the ; PICkit. The resolution and fault queue size are set based on ; constants in the firmware. To set the alert temperature of the ; MCP9800, turn the potentiometer RP1 to select a temperature from 15 ; to 48 degrees Celsius (59 to 118 degrees Fahrenheit). When the alert ; temperature changes, the MCP9800 set point and hysteresis will be ; programmed with the new selection. ; The temperature reading from the MCP9800 is monitored and sent to the ; PICtail for display on the seven-segment LED's. By default, the ; temperature is displayed in Celsius. To display the temperature in ; Fahrenheit, press and hold switch SW1. The temperature is read and ; the display is updated approximately four times per second. ; This firmware can also respond to commands from a PC through the ; USB port, similar to the Signal Analysis PICtail daughter board. ; This firmware supports the commands to return the firmware version ; and to return a single 10-bit value. The firmware will return the ; top ten bits of the temperature value, scaled such that 0 degrees ; Celsius is 512 counts. The other commands are stubbed out so the PC ; and the firmware do not get out of sync. ; NOTES: ; The PICkit gives us about 100us to notice that the clock line ; is low when it sends us a command. Since our chip is running at ; 8MHz, that gives us about 200 cycles. Since our timer interrupt is ; not critical, we will use an interrupt on change on Port A to watch ; for this transition rather than polling. We must disable the ; interrupt during the A/D conversion of the potentiometer, but since ; the conversion requires only 43 cycles, it is not a problem. ; The MCP9800 requires 1-2ms to complete its power-on sequence before ; we can configure it. We can easily account for this requirement by ; enabling the PIC16F684's power-up timer. ; Version Date Description ;-------------------------------------------------------------------- ; 0.00.01 03-Dec-2004 KLO Initial Release ; 0.00.02 08-Dec-2004 KLO Debug Release for start-up issue ; 0.00.03 08-Dec-2004 KLO Power-up timer enabled, default Celsius, ; constant update rate #include "project.inc" #include "comm.inc" #include "I2CBUS.INC" ;******************************************************************** ;******************************************************************** ; User Defined Constants ; ; These values may be modified for your application. To make it ; easier to read, the default radix for this section is decimal. ;******************************************************************** ;******************************************************************** list r=DEC ; Set the fault queue size to control how many consecutive conversions ; Ta must remain above Tset to assert Alert and Ta must remain below ; Thyst to deassert Alert. This value can be 1, 2, 4, or 6. #define FAULT_QUEUE_SIZE 1 ; Set the conversion resolution to the number of bits calculated for ; each temperature conversion. This value can be 9, 10, 11, or 12. #define CONVERSION_RESOLUTION 12 ; Set the delta between the alert temperature and the hysteresis ; temperature. Thyst will be programmed to the alert temperature minus ; this value in degrees Celsius. This value can be 1-10. #define THYST_DELTA 5 ;******************************************************************** ;******************************************************************** ; End User Constants ;******************************************************************** ;******************************************************************** ;-------------------------------------------------------------------- ; Check User Constants ;-------------------------------------------------------------------- #if FAULT_QUEUE_SIZE == 1 #define FAULT_QUEUE b'00000000' #else #if FAULT_QUEUE_SIZE == 2 #define FAULT_QUEUE b'00001000' #else #if FAULT_QUEUE_SIZE == 2 #define FAULT_QUEUE b'00010000' #else #if FAULT_QUEUE_SIZE == 2 #define FAULT_QUEUE b'00011000' #else error 'Fault Queue Size incorrectly specified.' #endif #endif #endif #endif #if CONVERSION_RESOLUTION == 9 #define RESOLUTION b'00000000' #else #if CONVERSION_RESOLUTION == 10 #define RESOLUTION b'00100000' #else #if CONVERSION_RESOLUTION == 11 #define RESOLUTION b'01000000' #else #if CONVERSION_RESOLUTION == 12 #define RESOLUTION b'01100000' #else error 'Conversion Resolution incorrectly specified.' #endif #endif #endif #endif #if (THYST_DELTA < 1) || (THYST_DELTA > 10) error 'Thyst Delta incorrectly specified.' #endif list r=HEX ;-------------------------------------------------------------------- ; End Check ;-------------------------------------------------------------------- ;-------------------------------------------------------------------- ; Define Configuration Bits ; Power-up Timer - Enabled to account for start-up delay of MCP9800. ; Oscillator - Internal RC, Clock-out, to monitor chip operation. ; Internal RC, No Clock-out can also be used. ;-------------------------------------------------------------------- __config _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_CLKOUT ;-------------------------------------------------------------------- ; Define Constants ;-------------------------------------------------------------------- #define ADC_GO 0x02 #define ADC_INTERNAL_RC 0x70 #define ADC_ON 0x01 #define ADC_LEFT_JUSTIFIED 0x00 #define ADC_RIGHT_JUSTIFIED 0x80 #define ADC_REF_VDD 0x00 #define COMPARATOR_OFF 0x07 #define DELAY_COUNT 0x08 #define GEIE_MASK 0x80 #define RAIE_MASK 0x08 #define T0IE_MASK 0x20 #define OSC_4MHZ b'01100000' #define OSC_8MHZ b'01110000' #define OSC_STS_INTRC b'00000000' #define OSC_STABLE b'00000110' #define OSC_USE_CONFIG_BITS b'00000000' #define OPTION_PS_256 b'00000111' #define OPTION_PULLUPS_ON b'00000000' #define OPTION_PULLUPS_OFF b'10000000' ;-------------------------------------------------------------------- ; Reserve space for interrupt save/restore ;-------------------------------------------------------------------- udata_shr ISR_W res 1 ISR_PCLATH res 1 ISR_STATUS res 1 ;-------------------------------------------------------------------- ; Reserve space for variables ;-------------------------------------------------------------------- udata AlertTemp res 1 BCD100 res 1 BCD10 res 1 BCD1 res 1 BCD10th res 1 BCD100th res 1 DelayCounter res 1 DigitsSent res 1 Groups res 1 IsNegative res 1 NewAlert res 1 PCReading res 2 RawReading res 2 ReadyToConvert res 1 Scratch res 3 ShiftCount res 1 SPIcounter res 1 SPIdata res 1 SwitchReading res 1 Temp res 1 Temperature res 3 ;****************************************************************************** ; Reset Vector ;****************************************************************************** STARTUP code goto Init ; Set up the reset and interrupt nop ; vectors. nop nop goto ISR ;****************************************************************************** ; Main Line ;****************************************************************************** code ;****************************************************************************** ; Initialization ;****************************************************************************** Init bsf STATUS, RP0 ; First, get the oscillator running errorlevel -302 ; at the desired frequency. movlw OSC_8MHZ | OSC_STS_INTRC | OSC_STABLE | OSC_USE_CONFIG_BITS movwf OSCCON bcf STATUS, RP0 errorlevel +302 movlw COMPARATOR_OFF ; Initialize Bank 0 registers. movwf CMCON0 movlw PORTC_INIT movwf PORTC movlw ADC_LEFT_JUSTIFIED | ADC_REF_VDD | ADC_ON movwf ADCON0 bsf STATUS, RP0 ; Initialize Bank 1 registers. errorlevel -302 movlw OPTION_PULLUPS_ON | OPTION_PS_256 movwf OPTION_REG movlw b'11111111' movwf TRISA movlw TRISC_INIT movwf TRISC clrf ANSEL movlw ADC_INTERNAL_RC movlw ADCON1 bsf IOCA, INT_ON_CLOCK_PIN bcf STATUS, RP0 errorlevel +302 movlw MCP9800_TSET_DEFAULT ; Initialize all global variables. movwf AlertTemp ; Initialize the LED value after the movlw DELAY_COUNT ; default gain and channel are set. movwf DelayCounter clrf I2C_ErrorCode clrf I2C_Flags clrf ReadyToConvert movlw GEIE_MASK | RAIE_MASK | T0IE_MASK movwf INTCON ; Enable interrupts. We need to ; enable the Port A interrupt as soon ; as possible so we can respond to a ; version check from the PC. call ProgramConfigReg ; Initialize the MCP9800. call ProgramAlertTemperature ;****************************************************************************** ;****************************************************************************** ; Main Loop ;****************************************************************************** ;****************************************************************************** MainLoop btfss ReadyToConvert, 0 ; Wait some time so we update the goto MainLoop ; display in a readable time frame. bcf ReadyToConvert, 0 ; Read and display the ambient call GetAlertTemperature ; temperature. call ReadTemperature call ConvertTemperature call ConvertToBCD call DisplayTemperature goto MainLoop ;****************************************************************************** ; GetAlertTemperature ; ; This routine calculates the alert temperature from the potentiometer on the ; PICkit. It converts the A/D reading to a value from 10 to 55 degrees ; Celsius. If this value is different from the current alert temperature, the ; MCP9800 is programmed with the new value. ; ; Input: None ; Output: AlertTemp Alert Temperature of the MCP9800 ; Side Effects: WREG destroyed ; PORTA interrupt temporarily disabled ;****************************************************************************** GetAlertTemperature bsf STATUS, RP0 ; Configure RP1 as an analog input errorlevel -302 ; and disable the interrupt on change movlw RP1_ANSEL ; on port A. movwf ANSEL bcf IOCA, INT_ON_CLOCK_PIN bcf STATUS, RP0 errorlevel +302 movlw ADC_LEFT_JUSTIFIED | ADC_REF_VDD | RP1_ADC_CHANNEL | ADC_ON movwf ADCON0 ; Start the A/D conversion, and wait call ADCSettlingDelay ; until it's done. The conversion bsf ADCON0, GO ; takes 43 cycles, so we can safely WaitForRP1 ; ignore the PIC16C745 clock line. btfss ADCON0, NOT_DONE goto RP1_Done goto WaitForRP1 RP1_Done bsf STATUS, RP0 ; Configure the line back as digital errorlevel -302 ; and enable the interrupt so we know clrf ANSEL ; when the PIC16C745 is talking to us. bsf IOCA, INT_ON_CLOCK_PIN bcf STATUS, RP0 errorlevel +302 movlw 0xF0 ; Convert the potentiometer reading andwf ADRESH, w ; to the alert temperature. First, movwf NewAlert ; get just the top four bits and put swapf NewAlert, f ; them in the lower nibble. Then movf NewAlert, w ; convert that to a value between 10 addwf NewAlert, w ; and 55 degrees Celsius by multiplying addwf NewAlert, w ; by three and adding 10. addlw d'10' movwf NewAlert subwf AlertTemp, w ; If the alert temperature has not btfsc STATUS, Z ; changed, exit without reprogramming goto AlertSelectDone ; the MCP9800. movf NewAlert, w ; Store the new alert temperature and movwf AlertTemp ; program the MCP9800. call ProgramAlertTemperature AlertSelectDone return ;****************************************************************************** ; ReadTemperature ; ; This routine reads the ambient temperature value from the MCP9800. It also ; converts this reading to a value that can be sent to the PC. Since the ; PCReading registers will be sent during an interrupt, disable interrupts ; while we update the value, so we do not send garbage. ; ; Input: None ; Output: RawReading registers Raw temperature value ; PCReading registers Scaled temperature reading for ; sending to the PC ; Side Effects: WREG destroyed ;****************************************************************************** ReadTemperature call I2C_StartBit ; Get the raw ambient movlw (MCP9800_ADDRESS << 1) | I2C_WRITE ; temperature reading call I2C_TransmitByte ; from the MCP9800. movlw MCP9800_TEMPERATURE call I2C_TransmitByte call I2C_StartBit movlw (MCP9800_ADDRESS << 1) | I2C_READ call I2C_TransmitByte call I2C_ReceiveByte movwf RawReading call I2C_SendACK call I2C_ReceiveByte movwf RawReading+1 call I2C_SendNAK call I2C_StopBit bcf INTCON, GIE ; Disable interrupts so we can update ; PCReading. movf RawReading, w ; Get the value ready for sending to addlw h'80' ; the PC. Shift up the raw reading such movwf PCReading ; that the lowest temperature reading is 0 movf RawReading+1, w ; and the highest temperature value is movwf PCReading+1 ; 4095. movlw 6 ; Shift over the value such that the movwf ShiftCount ; ten most significant bits are right ShiftOneBit ; justified. bcf STATUS, C rrf PCReading, f rrf PCReading+1, f decfsz ShiftCount, f goto ShiftOneBit bsf INTCON, GIE ; We are done with updating PCReading, ; so enable interrupts. return ;****************************************************************************** ; ConvertTemperature ; ; This routine converts the temperature to the desired units, Fahrenheit or ; Celsius. It also converts the temperature to a positive value, with the sign ; indicator stored in another byte. ; ; We multiply the temperature by 9 by shifting the original value three times ; to multiply by 8, and then adding the original value back in to multiply by 9. ; When we are done, the final value will be in the Scratch registers. We then ; divide by 5 by seeing how many times we can subtract 5 from the number (or add ; 5 to the number if the original value was negative). When we are done with ; this step, the answer will be in the Temperature registers. Then we add 32, ; shifted over one byte to allow for the fractional portion. ; ; Note that the switch is active low. ; ; Input: RawReading registers Raw temperature value ; Output: Temperature registers Absolute value of converted ; temperature value ; IsNegative Sign of converted temperature value ; Side Effects: WREG destroyed ;****************************************************************************** ConvertTemperature clrw ; Copy the raw data into the btfsc RawReading, 7 ; conversion areas. Sign extend the movlw 0xFF ; value into the upper bytes. movwf Temperature movwf Scratch movf RawReading, w movwf Temperature+1 movwf Scratch+1 movf RawReading+1, w movwf Temperature+2 movwf Scratch+2 CheckSwitch movf SW1_PORT, w ; Read SW1 to see if we're going to andlw SW1_MASK ; convert the temperature to deg F. movwf SwitchReading ; Read the switch twice. If the two xorwf SW1_PORT, w ; readings are the same, we're done. andlw SW1_MASK btfsc STATUS, Z goto SwitchDone movf SwitchReading, w ; Read the switch one more time. If xorwf SW1_PORT, w ; it now matches the first reading, andlw SW1_MASK ; we're done. btfss STATUS, Z goto SwitchDone movf SwitchReading, w ; The last two readings were the same xorlw SW1_MASK ; and were opposite the first reading. andlw SW1_MASK ; Flip the first reading and go on. movwf SwitchReading SwitchDone btfsc SwitchReading, SW1_BIT ; If the switch is not pressed, leave goto CheckSign ; the temperature in Celsius. Fahrenheit movlw 3 ; Convert the temperature to movwf ShiftCount ; Fahrenheit. First, multiply the Times2 ; value by eight by shifting. bcf STATUS, C rlf Scratch+2, f rlf Scratch+1, f rlf Scratch, f decfsz ShiftCount, f goto Times2 movf Temperature+2, w ; Then add one more back in, as addwf Scratch+2, f ; saved in Scratch, to multiply by movf Temperature+1, w ; nine. Note that this it 3-byte btfss STATUS, C ; addition, so we have to watch for goto NoCarry1 ; propagation of the carry. When we incf Scratch+1, f ; are done, the result is in Scratch. btfsc STATUS, Z incf Scratch, f NoCarry1 addwf Scratch+1, f movf Temperature, w btfsc STATUS, C incf Scratch, f addwf Scratch, f Div5 clrf Temperature ; Get ready to divide by 5. We will clrf Temperature+1 ; handle positive and negative numbers clrf Temperature+2 ; separately. btfsc Scratch, 7 goto Add5 goto Subtract5 ; Skip the increment on the first time ; around. DividePositive incf Temperature+2, f ; Increment the count of how many times btfss STATUS, Z ; 5 went into the number. goto Subtract5 incf Temperature+1, f btfsc STATUS, Z incf Temperature, f Subtract5 movlw 5 ; Subtract 5 from the number. Account subwf Scratch+2, f ; for borrows across all three bytes. We btfsc STATUS, C ; need the carry flag, so we cannot use goto NoCarry2 ; decrement. movlw 1 subwf Scratch+1, f btfss STATUS, C decf Scratch, f NoCarry2 btfss Scratch, 7 ; If we haven't gone negative, subtract goto DividePositive ; 5 again. Otherwise, we're done. goto Add32 DivideNegative incf Temperature+2, f ; Increment the count of how many times btfss STATUS, Z ; 5 went into the number. goto Add5 incf Temperature+1, f btfsc STATUS, Z incf Temperature, f Add5 movlw 5 ; Add 5 to the number. Account addwf Scratch+2, f ; for carries across all three bytes. btfss STATUS, C goto NoCarry3 incf Scratch+1, f btfsc STATUS, Z incf Scratch, f NoCarry3 btfsc Scratch, 7 ; If we haven't gone positive, add goto DivideNegative ; 5 again. Otherwise, we need to see movf Scratch+2, f ; if we hit 0 exactly. If we did, we btfsc STATUS, Z ; need to loop one more time to count goto DivideNegative ; that last subtraction. Since we're ; subtracting only 5, we only need to ; look at the least significant byte. comf Temperature+2, f ; Since we started out with a comf Temperature+1, f ; negative number, we must make our comf Temperature, f ; answer negative. incf Temperature+2, f btfsc STATUS, Z incf Temperature+1, f btfsc STATUS, Z incf Temperature, f Add32 movlw d'32' ; Add 32 to complete the conversion. addwf Temperature+1, f ; Note that the third byte is the btfsc STATUS, C ; fractional portion, so we add to the incf Temperature, f ; second byte. CheckSign clrf IsNegative ; See if the temperature reading is btfss Temperature, 7 ; positive. If it is, we are done. goto ConversionDone comf IsNegative, f ; Set the sign indicator and convert comf Temperature+2, f ; the temperature to a positive value. comf Temperature+1, f comf Temperature, f incf Temperature+2, f btfsc STATUS, Z incf Temperature+1, f btfsc STATUS, Z incf Temperature, f ConversionDone return ;****************************************************************************** ; ConvertToBCD ; ; This routine converts the temperature value into BCD digits that can be ; displayed on the seven-segment display by the PIC16F737. We could just ; convert the digits as needed, but it uses the same amount of code space, ; and this looks cleaner. ; ; Since we do not have a digit carry status bit, we will calculate the BCD ; values by repetatively subtracting the digit values. ; ; Input: Temperature registers Absolute value of converted ; temperature value ; Output: BCDxxx registers BCD equivalent of the temperature ; Side Effects: WREG destroyed ; Temperature registers destroyed ;****************************************************************************** ConvertToBCD clrf BCD100 ; Find the BCD 100's digit. To save goto Subtract100 ; code, this portion is structured ; differently from the other digits. ; We need to do multiple precision math, ; so to minimize the math, we increment ; after we know the subtraction is valid, ; and save the old value in case it was ; not. Next100 incf BCD100, f ; Increment the 100's digit. Subtract100 movlw d'100' ; Subtract 100 from the integer part subwf Temperature+1, w ; of the temperature. Note that this is movwf Scratch+1 ; 16-bit math. If we didn't borrow, we btfsc STATUS, C ; do not have to worry about the upper goto NoBorrow100 ; byte. movlw 1 ; We had to borrow from the upper subwf Temperature, w ; byte. Continue the subtraction. If we btfss STATUS, C ; borrow again, we have no more 100's, goto Check10s ; and BCD100 and Temperature+1 are ready ; for the next digit. movwf Temperature ; The subtraction was successful, so ; store the result for the next pass. NoBorrow100 movf Scratch+1, w ; Get the result of the first byte movwf Temperature+1 ; subtraction and get it ready for the goto Next100 ; next pass. Check10s clrf BCD10 ; Get ready to determine the 10's movlw d'10' ; digit. Subtract10 incf BCD10, f ; Since we are not doing multiple subwf Temperature+1, f ; precision math, we can save some code btfsc STATUS, C ; by incrementing first and patching up goto Subtract10 ; in case we subtract too much. ; Increment the digit and subtract 10 ; from the temperature. If we go less ; than 0, we are done. Done10 decf BCD10, f ; We subtracted one too many times, addwf Temperature+1, w ; so correct the number and the digit. Check1s movwf BCD1 ; Whatever is left is the one's digit. clrw ; Calculate the fractional portion of btfsc Temperature+2, 7 ; the temperature in hundredths. addlw d'50' btfsc Temperature+2, 6 addlw d'25' btfsc Temperature+2, 5 addlw d'13' btfsc Temperature+2, 4 addlw d'6' movwf Temperature+2 Check10ths clrf BCD10th ; Get ready to calculate the 10th's movlw d'10' ; digit. Subtract10th incf BCD10th, f ; Increment the digit and subtract 10 subwf Temperature+2, f ; from the hundredths. If we go less btfsc STATUS, C ; than 0, we are done. goto Subtract10th Done10th decf BCD10th, f ; We subtracted one too many times, addwf Temperature+2, w ; so correct the number and the digit. Check100ths movwf BCD100th ; Whatever is left is the hundredths ; digit. return ;****************************************************************************** ; DisplayTemperature ; ; This routine sends the BCD temperature digits to the PIC16F737 for display on ; the seven-segment display. ; ; Input: BCDxxx registers BCD equivalent of the temperature ; IsNegative Sign of converted temperature value ; Output: None ; Side Effects: WREG destroyed ;****************************************************************************** DisplayTemperature movlw DISPLAY_DIGITS ; Initialize the number of digits movwf DigitsSent movlw DISPLAY_START ; Send the start byte. call BitBangSPI btfss IsNegative, 0 ; If the temperature is negative, goto Check100Digit ; send a dash for the negative sign. movlw DISPLAY_DASH call BitBangSPI decf DigitsSent, f Check100Digit movf BCD100, w ; See if the 100's digit is 0. btfsc STATUS, Z goto Check10Digit call BitBangSPI ; If the 100's digit is not 0, send decf DigitsSent, f ; it. Then go to send the 10's digit. goto Send10Digit Check10Digit movf BCD10, w ; See if the 10's digit is 0. btfss STATUS, Z goto Send10Digit movf DigitsSent, f ; See if we're still trying to send xorlw DISPLAY_DIGITS ; the first digit. btfsc STATUS, C goto Send1Digit movlw DISPLAY_BLANK ; If we haven't sent a digit yet, call BitBangSPI ; then send a blank. decf DigitsSent, f goto Send1Digit Send10Digit movf BCD10, w ; Send the 10's digit if it is not 0 call BitBangSPI ; or if we sent the 100's digit. decf DigitsSent, f Send1Digit movf BCD1, w ; Send the 1's digit with a trailing iorlw DISPLAY_DOT ; decimal point. Then see if we have call BitBangSPI ; more digits available. decfsz DigitsSent, f goto Send10thDigit goto DigitsDone Send10thDigit movf BCD10th, w ; Send the 10th's digit. Then see if call BitBangSPI ; we have more digits available. decfsz DigitsSent, f goto Send100thDigit goto DigitsDone Send100thDigit movf BCD100th, w ; Send the 100th's digit. call BitBangSPI DigitsDone return ;****************************************************************************** ;****************************************************************************** ; Interrupt Service Routine ;****************************************************************************** ;****************************************************************************** ISR movwf ISR_W ; Save off the current context of movf STATUS,w ; W, STATUS, and PCLATH movwf ISR_STATUS movf PCLATH,w movwf ISR_PCLATH btfsc INTCON, RAIF goto PortAChangeISR btfss INTCON, T0IF goto ISR_Exit ;------------------------------------------------------------------------------ ; TimerISR ; ; We need to time approximate 250ms for the update of the temperature. If we ; use the maximum prescaler and let the timer roll over from a full count, we ; get a delay, at 8MHz, of 65536 cycles. At 8MHz, 250ms requires 500000 cycles, ; or approximately 8 interrupts. When we count 8 interrupts, we will set a ; flag. TimerISR bcf INTCON, T0IF ; If we have not waited for decfsz DelayCounter ; enough interrupts, continue. goto ISR_Exit bsf ReadyToConvert, 0 ; It is time to begin another movlw DELAY_COUNT ; conversion. Set the flag and reset movwf DelayCounter ; the counter for the next pass. ;------------------------------------------------------------------------------ ; PortAChangeISR ; ; If we get a change on the PORTA pin that we are monitoring, the PIC16C745 ; may be trying to talk to us. PortAChangeISR bcf INTCON, RAIF ; See if the PC is trying to ;call CheckComm ; communicate. ;------------------------------------------------------------------------------ ISR_Exit movf ISR_PCLATH,w ; Restore context and return to the movwf PCLATH ; main processing. Be sure to restore movf ISR_STATUS,w ; W without corrupting the STATUS bits. movwf STATUS swapf ISR_W,f swapf ISR_W,w retfie ;****************************************************************************** ; CheckComm ; ; Since the PORTA interrupt is not usable when we're multiplexing between ; input and output, we have to poll for communications ; Time if no clock: 16 cycles ; Input: None ; Output: None ; Side Effects: WREG destroyed ; Requires: Comm.GetByte ; Comm.SendByte ;****************************************************************************** CheckComm btfsc CLOCKPIN ; If the clock pin is high, exit. goto CommDone call Comm.GetByte ; Get a byte from the PIC16C745. andlw 0xF8 ; Check for any errors in W. btfss STATUS,Z goto CommDone pageselw CommandTableStart movlw CommandTableStart ; Get the byte read and use it to addwf Comm.RxTxByte,w ; index into our jump table. If btfsc STATUS,C ; we crossed a 256 byte boundary, then incf PCLATH,f ; increment PCLATH. Then load the movwf PCL ; program counter with computed goto. CommandTableStart goto GetVersion ; 0x00 - Get Version goto GetRTSample ; 0x01 - Get Real Time sample goto Configure ; 0x02 - stub goto Go ; 0x03 - stub goto ReadBuffer ; 0x04 - Read Buffer, just sends Vout goto AreYouThroughYet ; 0x05 goto CommDone ; 0x06 goto CommDone ; 0x07 ;------------------------------------------------------------------------------ GetVersion call BusTurnAroundDelay movlw VERSION ; Send the encoded version number call Comm.SendByte ; back to the PC. goto CommDone ;------------------------------------------------------------------------------ GetRTSample call BusTurnAroundDelay movf PCReading,w ; Send the Vout value back to the call Comm.SendByte ; PC, high byte first. movf PCReading+1,w call Comm.SendByte goto CommDone ;------------------------------------------------------------------------------ Configure call Comm.GetByte ; Stub out this function for call Comm.GetByte ; compatibility. call BusTurnAroundDelay goto CommDone ;------------------------------------------------------------------------------ Go goto CommDone ; Stub out this function for ; compatibility. ;------------------------------------------------------------------------------ AreYouThroughYet call BusTurnAroundDelay ; For compatibility only. movlw '.' call Comm.SendByte goto CommDone ;------------------------------------------------------------------------------ ReadBuffer call Comm.GetByte ; For compatibility only. movwf Temp ReadBufferLoop call BusTurnAroundDelay movf PCReading, w call Comm.SendByte decfsz Temp,f goto ReadBufferLoop goto CommDone ;------------------------------------------------------------------------------ CommDone retlw 0 ;****************************************************************************** ; ProgramConfigReg ; ; This routine uses I2C routines to program the configuration register based ; on constants in the code. ; ; Input: None ; Output: None ; Side Effects: WREG destroyed ; Time: 723 cycles ;****************************************************************************** ProgramConfigReg call I2C_StartBit movlw (MCP9800_ADDRESS << 1) | I2C_WRITE call I2C_TransmitByte movlw MCP9800_CONFIGURATION call I2C_TransmitByte movlw MCP9800_ONESHOT_OFF|RESOLUTION|FAULT_QUEUE|MCP9800_ALERT_ACTIVE_HIGH|MCP9800_COMP_MODE|MCP9800_SHUTDOWN_OFF call I2C_TransmitByte call I2C_StopBit retlw 0 ;****************************************************************************** ; ProgramAlertTemperature ; ; This routine programs the alert temperature to the value in AlertTemp. It ; then programs the hysteresis register to the alert temperature minus the ; value of THYST_DELTA. The least significant bits of both temperatures are ; programmed to 0. ; ; Input: None ; Output: None ; Side Effects: WREG destroyed ;****************************************************************************** ProgramAlertTemperature call I2C_StartBit ; Program the limit movlw (MCP9800_ADDRESS << 1) | I2C_WRITE ; set register to the call I2C_TransmitByte ; alert temperature. movlw MCP9800_LIMITSET call I2C_TransmitByte movf AlertTemp, w call I2C_TransmitByte clrw call I2C_TransmitByte call I2C_StopBit nop nop nop call I2C_StartBit ; Program the movlw (MCP9800_ADDRESS << 1) | I2C_WRITE ; hysteresis register call I2C_TransmitByte ; to a value THYST_DELTA movlw MCP9800_HYSTERESIS ; degrees below the call I2C_TransmitByte ; alert temperature. movlw THYST_DELTA subwf AlertTemp, w call I2C_TransmitByte clrw call I2C_TransmitByte call I2C_StopBit retlw 0 ;****************************************************************************** ; BitBangSPI ; ; This routine sends the value in W to the PIC16F737 using a bit-banged ; SPI protocol. Note that this routine uses an idle low clock. ; ; Input: WREG ; Output: None ; Side Effects: WREG destroyed ;****************************************************************************** BitBangSPI movwf SPIdata ; Save off W so we can check for ; communications without losing the ; value. movlw h'08' ; Set up a counter to send out the movwf SPIcounter ; 8 bits. SendSPI btfsc SPIdata, 7 ; Check the MSBit of the byte to send. bsf SPI_DATA ; If it is set, then set the data line bsf SPI_CLOCK ; high (default is low). Pulse the bcf SPI_CLOCK ; clock line high, then low. Then bcf SPI_DATA ; clear the data line. rlf SPIdata,f ; Rotate the byte we're sending to decfsz SPIcounter, f ; get the next bit in the MSBit. If we goto SendSPI ; haven't done all 8 bits, loop back up. retlw 0 ;****************************************************************************** ; BusTurnAroundDelay ; ; This routine is called as part of the protocol to talk to the PIC16C745 ; ; Input: None ; Output: None ; Side Effects: WREG destroyed ;****************************************************************************** BusTurnAroundDelay if CLOCKSPEED == .4000000 movlw .60 ; 4 Mhz delay else if CLOCKSPEED == .8000000 movlw .120 ; 8 Mhz delay else if CLOCKSPEED == .20000000 movlw 0 ; 20 Mhz delay else messg "HalfBitTime delay not configured for clockspeed" endif endif endif movwf Temp decfsz Temp,f goto $-1 return ;****************************************************************************** ; ADCSettlingDelay ; ; This delay routine is used to wait for the ADC to settle after selecting the ; channel (>=12 microseconds). ; ; Input: None ; Output: None ; Side Effects: WREG destroyed ; Time: 12 cycles (4 MHz) ; 24 cycles (8 MHz) ;****************************************************************************** ADCSettlingDelay if CLOCKSPEED == .4000000 movlw 3 ; 4 Mhz delay else if CLOCKSPEED == .8000000 movlw 7 ; 8 Mhz delay endif endif movwf Temp decfsz Temp, f goto $-1 return end