;------------------------------------------------------------------------------------------------------------------------ ; Source code for the PIC16F873 based Digital Light and Temp. Reader. ;------------------------------------------------------------------------------------------------------------------------ ; ; **Analog Pinouts ; Analog Voltage Input - RA0 (Temp), RA1 (Light). ; Low Voltage Reference - Vss ; High Voltage Reference - RA3, 2.56V ; Resolution = 2.56V / 1024 = 2.5mV / bit. ; ; **USART Pinouts ; Transmit Data - RC6 (TX) ; ; **Modes ; Debug Mode - RC4 (Low = Debug, High = User) ; Infra Mode - RC5 (Low = Enabled, High = Disabled) ; ; **LCD Pinouts ; 1 Vss - Ground, 3rd pin of the potentiometer ; 2 Vcc - 5V DC, 1st pin of the potentiometer ; 3 Vee - Middle pin of the potentiometer ; 4 RS - RC0 (Data - 1, Instruction - 0) ; 5 R/W - RC1 (R - 1, W - 0) ; 6 E - RC2 (Enable Pulse) ; 7 DB0 - RB0 (LSB) ; 8 DB1 - RB1 ; 9 DB2 - RB2 ; 10 DB3 - RB3 (Lower 4 bits) ; 11 DB4 - RB4 (Upper 4 bits) ; 12 DB5 - RB5 ; 13 DB6 - RB6 ; 14 DB7 - RB7 (MSB) ; ; Instruction Cycle Time = 1 / (4MHz / 4) = 1us per instruction ;------------------------------------------------------------------------------------------------------------------------ LIST P=16F873 INCLUDE "p16f873.inc" ; ERRORLEVEL -302 __CONFIG _PWRTE_OFF & _HS_OSC & _WDT_OFF & _WRT_ENABLE_ON & _LVP_OFF & _BODEN_OFF; configuration switches CBlock 0x20 N ; Delay registers. FIXDELAY visdelay dataL rmng_num ; Digit breaker registers. quotient temp_num tempL ; Temp. variable registers. tempH tempCfract digittempdata0 ; Temp Data digit registers. digittempdata1 digittempdata2 digittempdataL0 digittempdataL1 digittempdataL2 tempnonfract0 ; Actual temperature digit registers. tempnonfract1 tempnonfract2 tempfract0 tempfract1 briteL ; Brightness variable registers. briteH britefract digitbritedata0 ; Brightness data digit registers. digitbritedata1 digitbritedata2 digitbritedataL0 digitbritedataL1 digitbritedataL2 britenonfract0 ; Actual temperature digit registers. britenonfract1 britenonfract2 britefract0 britefract1 tempHtrans ; Data to be passed to PC. tempLtrans briteHtrans briteLtrans ENDC org 0x00 nop ; Reserved for ICD II. goto start start call initports ; Initialize Ports as output/inputs. call setupUART ; Setup USART. call delay ; Delay for USART settling time. call INITLCD ; Initialize LCD. main call tempconv ; Convert temperature readings. call briteconv ; Convert brightness readings. call passdata2pc ; Pass data to PC. call displaydata ; Display the calculated data, either in Debug or User mode. call visualdelay ; Visual delay for the to view data. goto main ;------------------------------------------------------------------------------------------------------------------------ ; Subroutine to initialize the PORTs as Inputs or Outputs. ;------------------------------------------------------------------------------------------------------------------------ initports clrf PORTB clrf PORTC banksel TRISB ; All PORTB pins as output. movlw b'00000000' movwf TRISB banksel TRISC ; Pins RC0-RC3 and RC6 as output. movlw b'10110000' ; Pins RC4-RC5 and RC7 as input. movwf TRISC return ;------------------------------------------------------------------------------------------------------------------------ ; Initialize the LCD. ;------------------------------------------------------------------------------------------------------------------------ INITLCD BANKSEL PORTB ; Select Bank for PORTB. MOVLW 0xE6 ; Call for 46ms delay CALL NDELAY ; Wait for VCC of the LCD to reach 5V BCF PORTC, 0 ; Clear RS to select Instruction Reg. BCF PORTC, 1 ; Clear R/W to write MOVLW B'00111011' ; Function Set to 8 bits, 2 lines and 5x7 dot matrix MOVWF PORTB CALL ENABLEPULSE CALL DELAY50 CALL ENABLEPULSE CALL DELAY50 CALL ENABLEPULSE CALL DELAY50 ; Call 50us delay and wait for instruction completion MOVLW B'00001000' ; Display OFF MOVWF PORTB CALL ENABLEPULSE CALL DELAY50 ; Call 50us delay and wait for instruction completion MOVLW B'00000001' ; Clear Display MOVWF PORTB CALL ENABLEPULSE MOVLW 0x09 ; Call 1.8ms delay and wait for instruction completion CALL NDELAY MOVLW B'00000010' ; Cursor Home MOVWF PORTB CALL ENABLEPULSE MOVLW 0x09 ; Call 1.8ms delay and wait for instruction completion CALL NDELAY MOVLW B'00001100' ; Display ON, Cursor OFF, Blinking OFF MOVWF PORTB CALL ENABLEPULSE CALL DELAY50 ; Call 50us delay and wait for instruction completion MOVLW B'00000110' ; Entry Mode Set, Increment & No display shift MOVWF PORTB CALL ENABLEPULSE CALL DELAY50 ; Call 50us delay and wait for instruction completion BSF PORTC, 0 ; Set RS to select Data Reg. BCF PORTC, 1 ; Clear R/W to write RETURN ;------------------------------------------------------------------------------------------------------------------------ ; Enable Pulse for writing or reading instructions or data ;------------------------------------------------------------------------------------------------------------------------ ENABLEPULSE BCF PORTC, 2 ; 2us LOW followed by 3us HIGH Enable Pulse and 2us LOW. NOP NOP BSF PORTC, 2 NOP NOP NOP BCF PORTC, 2 NOP NOP RETURN ;------------------------------------------------------------------------------------------------------------------------ ; N DELAY SUBROUTINE, delay in multiples of 200us up to 200us*255 = 51ms (or more) ;------------------------------------------------------------------------------------------------------------------------ NDELAY MOVWF N ; N is delay multiplier NOTOVER CALL DELAY200 ; Call for 200us DECFSZ N, 1 ; Decrease N by 1 GOTO NOTOVER ; The delay isn't done RETURN ;------------------------------------------------------------------------------------------------------------------------ ; FIXED 200us DELAY (Possibly more due to execution time of the DECFSZ instruction.) ;------------------------------------------------------------------------------------------------------------------------ DELAY200 MOVLW 0x42 ; 66 LOOPS MOVWF FIXDELAY ; 200us fixed delay NOTDONE200 DECFSZ FIXDELAY, 1 ; Decrement of FIXDELAY GOTO NOTDONE200 ; If 200us isn't up go back to NOTDONE200 RETURN ; If 200us is up then return to instruction. ;------------------------------------------------------------------------------------------------------------------------ ; FIXED 50us DELAY (Possibly more due to execution time of the DECFSZ instruction.) ;------------------------------------------------------------------------------------------------------------------------ DELAY50 MOVLW 0x10 ; 16 LOOPS MOVWF FIXDELAY ; 50us fixed delay NOTDONE50 DECFSZ FIXDELAY, 1 ; Decrement of FIXDELAY GOTO NOTDONE50 ; If 50us isn't up go back to NOTDONE50 RETURN ; If 50us is up then return to instruction. ;------------------------------------------------------------------------------------------------------------------------ ; Visual delay subroutine. ;------------------------------------------------------------------------------------------------------------------------ visualdelay movlw 0x12 movwf visdelay seetemp movlw 0xFF call NDELAY decfsz visdelay, 1 goto seetemp return ;------------------------------------------------------------------------------------------------------------------------ ; Fast Directive to write characters to LCD. ;------------------------------------------------------------------------------------------------------------------------ PUTCHAR MOVWF PORTB ; A quicker way of writing characters to LCD. CALL ENABLEPULSE CALL CHKBUSY RETURN ;------------------------------------------------------------------------------------------------------------------------ ; Subroutine to check for the BUSY flag. Mostly used for instructions that follows up a character write. ;------------------------------------------------------------------------------------------------------------------------ CHKBUSY bcf PORTC, 0 ; Clear RS to select Instruction Reg. bsf PORTC, 1 ; Set R/W to read. banksel TRISB ; Select Bank for TRISC. movlw 0xFF ; Define all PORTC Pins as Inputs. movwf TRISB banksel PORTC ; Select Bank for PORTC. bsf PORTC, 2 ; I tried to write my own code for this part initially but I wasn't successful. movf PORTB, w ; Therefore, I implemented a portion of Peter Ouwehand's LCD Code. bcf PORTC, 2 ; Will look more into the BUSY flag of the LCD. andlw 0x80 ; Credits to Peter Ouwehand for his code here. :) btfss STATUS, Z goto CHKBUSY banksel TRISB ; Select Bank for TRISB. movlw 0x00 ; Define all PORTC Pins as Outputs. movwf TRISB banksel PORTC ; Select Bank for PORTA, B, and C. bsf PORTC, 0 ; Set RS to select Data Register. bcf PORTC, 1 ; Clear R/W to write. return ;------------------------------------------------------------------------------------------------------------------------ ; Position Cursor to the next line. ;------------------------------------------------------------------------------------------------------------------------ nextline banksel PORTC bcf PORTC, 0 ; Select Instructions Register. bcf PORTC, 1 ; Select Write. movlw b'11000000' ; Shift cursor to second line at 0x40 RAM address on LCD. call PUTCHAR return ;------------------------------------------------------------------------------------------------------------------------ ; Clear screen and Cursor home. ;------------------------------------------------------------------------------------------------------------------------ clrscreen banksel PORTC bcf PORTC, 0 ; Clear RS to select Instructions Register. bcf PORTC, 1 ; Clear R/W to select Write. banksel PORTB MOVLW B'00000001' ; Clear Display call PUTCHAR return ;------------------------------------------------------------------------------------------------------------------------ ; Position Cursor to home position. ;------------------------------------------------------------------------------------------------------------------------ cursorhome banksel PORTC bcf PORTC, 0 ; Select Instructions Register. bcf PORTC, 1 ; Select Write. movlw b'00000010' ; Position cursor to home position. call PUTCHAR return ;------------------------------------------------------------------------------------------------------------------------ ; Initialize ADC Subroutine ;------------------------------------------------------------------------------------------------------------------------ initadc banksel TRISA ; Select Bank for TRISA. movlw b'00111111' ; Initialize RA0 - RA5 as Inputs. movwf TRISA banksel ADCON1 ; Select Bank for ADCON1. movlw b'00000101' ; ADFM for Left Justified, Vref-=Vss Vref+=AN3 Analog In=AN0, AN1 (R/C = 1/2). movwf ADCON1 banksel ADCON0 ; Select Bank for ADCON0. movlw b'01000001' ; Fosc/8, Channel 0, Enable the ADC (Default Chan. 0) movwf ADCON0 return ;------------------------------------------------------------------------------------------------------------------------ ; Wait 20us for Acquisition time in order for holding capacitor to charge up. ;------------------------------------------------------------------------------------------------------------------------ delay20 banksel FIXDELAY ; A loop to generate 20us delay. movlw 0x0A movwf FIXDELAY notdone20 decfsz FIXDELAY, 1 goto notdone20 return ;------------------------------------------------------------------------------------------------------------------------ ; This routine starts the AD Conversion and waits for it to complete. ;------------------------------------------------------------------------------------------------------------------------ startadc banksel ADCON0 ; Select Bank for ADCON0. bsf ADCON0, GO ; Set the GO bit to begin AD Conversion. banksel ADCON0 ; Select Bank for ADCON0. checkdone btfsc ADCON0, GO ; Check if the conversion is done? goto checkdone ; If not, check again. return ; Else, return to the main programme. ;------------------------------------------------------------------------------------------------------------------------ ; Subroutine to setup the USART. ;------------------------------------------------------------------------------------------------------------------------ setupUART banksel SPBRG ; Load into SPBRG the value of 103 for Baud Rate of 2400 with error of 0.17%. movlw d'103' movwf SPBRG movlw b'00100100' ; Set 8 bit Transmission, Enable Transmit, Asynchronous Mode, High Speed. movwf TXSTA banksel RCSTA movlw b'10010000' ; Enable Serial Port, 8 bit Reception, Enable Continuous Receive. movwf RCSTA return ;------------------------------------------------------------------------------------------------------------------------ ; Delay to provide some settling time for start up. ;------------------------------------------------------------------------------------------------------------------------ delay banksel dataL clrf dataL settle decfsz dataL, f ; The delay loop. goto settle movf RCREG, w ; Flush the receive buffer. movf RCREG, w movf RCREG, w return ;------------------------------------------------------------------------------------------------------------------------ ; Receive character from RS232 and store in WREG. ;------------------------------------------------------------------------------------------------------------------------ receive banksel PIR1 waitrcv btfss PIR1, RCIF ; Wait for RCIF to be set, when set then receive buffur is full. goto waitrcv ; If not set, then keep waiting. movf RCREG, w ; If set, move buffer content to WREG. return ;------------------------------------------------------------------------------------------------------------------------ ; Transmit the character that is on WREG to RS232 and wait until the sending is complete. ;------------------------------------------------------------------------------------------------------------------------ transmit banksel TXREG movwf TXREG ; Move character to TXREG to be transmitted. banksel TXSTA waittrn btfss TXSTA, TRMT ; Check if buffer is empty. goto waittrn ; If no, then keep waiting. banksel PORTB ; If yes, select Bank 0 and return. return ;------------------------------------------------------------------------------------------------------------------------ ; Select Channel AN0 of A/D Converter. ;------------------------------------------------------------------------------------------------------------------------ chan0 banksel ADCON0 bcf ADCON0, 5 bcf ADCON0, 4 bcf ADCON0, 3 return ;------------------------------------------------------------------------------------------------------------------------ ; Select Channel AN1 of A/D Converter. ;------------------------------------------------------------------------------------------------------------------------ chan1 banksel ADCON0 bcf ADCON0, 5 bcf ADCON0, 4 bsf ADCON0, 3 return ;------------------------------------------------------------------------------------------------------------------------ ; Breaks down a number to its individual digits. ;------------------------------------------------------------------------------------------------------------------------ get_dig movlw d'10' ; To split the digits, divide them by 10. incf quotient, f ; Increment of quotient with each subtraction by 10. subwf rmng_num, f ; Subtract the number by 10. skpnc ; If already negative, stop division. goto get_dig ; Else, continue dividing. addwf rmng_num, f ; Restore number. decf quotient, f ; Restore quotient. movf rmng_num, w ; Move rmng_num to temp_num. movwf temp_num movf quotient, w ; Move quotient to rmng_num. movwf rmng_num movf temp_num, w return ;------------------------------------------------------------------------------------------------------------------------ ; Temperature Conversion Subroutine. ;------------------------------------------------------------------------------------------------------------------------ tempconv call initadc ; Initialize and begin ADC on AN0. call chan0 call delay20 ; Delay to charge up holding capacitor. call startadc ; Start ADC and await the completion. banksel ADRESH ; Pass high byte to tempH. movf ADRESH, w movwf tempH movwf tempHtrans banksel ADRESL ; Pass low byte to tempL. movf ADRESL, w banksel tempL movwf tempL movwf tempLtrans arrgtemp bcf STATUS, C ; Rearrange tempL from xx00 0000 to 0000 00xx. rlf tempL, f btfss STATUS, C goto $+2 bsf tempL, 0 bcf STATUS, C rlf tempL, f btfss STATUS, C goto $+2 bsf tempL, 0 brkdigtemp banksel tempH movf tempH, w movwf rmng_num clrf quotient ; Break ADC high byte result to individual digits to be displayed. call get_dig movwf digittempdata0 clrf quotient call get_dig movwf digittempdata1 clrf quotient call get_dig movwf digittempdata2 banksel tempL movf tempL, w movwf rmng_num clrf quotient ; Break ADC low byte result to individual digits to be displayed. call get_dig movwf digittempdataL0 clrf quotient call get_dig movwf digittempdataL1 clrf quotient call get_dig movwf digittempdataL2 calctempC banksel tempL movlw d'25' ; Assign multiplier and clear fractional temperature reading. clrf tempCfract mult25 addwf tempCfract, f ; Multiply ADRESL by 25 to obtain fractional temperature reading. decfsz tempL, f goto mult25 breaktempC movf tempH, w ; Break up temperature readings to ind. digits to be displayed. movwf rmng_num clrf quotient call get_dig movwf tempnonfract0 clrf quotient call get_dig movwf tempnonfract1 clrf quotient call get_dig movwf tempnonfract2 movf tempCfract, w movwf rmng_num clrf quotient call get_dig movwf tempfract0 clrf quotient call get_dig movwf tempfract1 return ;------------------------------------------------------------------------------------------------------------------------ ; Brightness Conversion Subroutine. ;------------------------------------------------------------------------------------------------------------------------ briteconv call initadc ; Initialize and begin ADC on AN1. call chan1 call delay20 ; Delay to charge up holding capacitor. call delay20 call startadc ; Start ADC and await the completion. banksel ADRESH ; Pass high byte to briteH. movf ADRESH, w movwf briteH movwf briteHtrans banksel ADRESL ; Pass low byte to briteL. movf ADRESL, w banksel briteL movwf briteL movwf briteLtrans arrgbrite bcf STATUS, C ; Rearrange briteL from xx00 0000 to 0000 00xx. rlf briteL, f btfss STATUS, C goto $+2 bsf briteL, 0 bcf STATUS, C rlf briteL, f btfss STATUS, C goto $+2 bsf briteL, 0 bcf STATUS, C ; Pass LSbit of briteH to 2nd bit of briteL. rrf briteH, f btfss STATUS, C goto $+2 bsf briteL, 2 chkbrite movlw d'30' ; Check if brightness is below 30%. subwf briteH, w skpc goto onbklit ; If yes, activate backlit. goto offbklit ; Else, off backlit. onbklit bsf PORTC, 3 goto brkdigbrite offbklit bcf PORTC, 3 goto brkdigbrite brkdigbrite banksel briteH movf briteH, w movwf rmng_num clrf quotient ; Break ADC high byte result to individual digits to be displayed. call get_dig movwf digitbritedata0 clrf quotient call get_dig movwf digitbritedata1 clrf quotient call get_dig movwf digitbritedata2 banksel briteL movf briteL, w movwf rmng_num clrf quotient ; Break ADC low byte result to individual digits to be displayed. call get_dig movwf digitbritedataL0 clrf quotient call get_dig movwf digitbritedataL1 clrf quotient call get_dig movwf digitbritedataL2 calcbrite banksel briteL movlw d'13' ; Assign multiplier and clear fractional brightness reading. clrf britefract mult13 addwf britefract, f ; Multiply ADRESL by 13 to obtain fractional brightness reading. decfsz briteL, f goto mult13 breakbrite movf briteH, w ; Break up brightness readings to ind. digits to be displayed. movwf rmng_num clrf quotient call get_dig movwf britenonfract0 clrf quotient call get_dig movwf britenonfract1 clrf quotient call get_dig movwf britenonfract2 movf britefract , w movwf rmng_num clrf quotient call get_dig movwf britefract0 clrf quotient call get_dig movwf britefract1 return ;------------------------------------------------------------------------------------------------------------------------ ; Check status on RC5 to determine whether to pass data to PC. ;------------------------------------------------------------------------------------------------------------------------ passdata2pc btfss PORTC, 5 goto transdata goto transdone transdata movf tempHtrans, w ; Pass temp results to PC. call transmit movf tempLtrans, w call transmit movf briteHtrans, w call transmit movf briteLtrans, w call transmit goto transdone transdone return ;------------------------------------------------------------------------------------------------------------------------ ; Check status on RC4 and display the data. ;------------------------------------------------------------------------------------------------------------------------ displaydata movlw d'48' ; Convert individual digits to ASCII. addwf digittempdata2, f addwf digittempdata1, f addwf digittempdata0, f addwf digittempdataL2, f addwf digittempdataL1, f addwf digittempdataL0, f addwf tempnonfract2, f addwf tempnonfract1, f addwf tempnonfract0, f addwf tempfract1, f addwf tempfract0, f addwf digitbritedata2, f addwf digitbritedata1, f addwf digitbritedata0, f addwf digitbritedataL2, f addwf digitbritedataL1, f addwf digitbritedataL0, f addwf britenonfract2, f addwf britenonfract1, f addwf britenonfract0, f addwf britefract1, f addwf britefract0, f btfss PORTC, 4 ; Check Pin 4 of PORTC. If HIGH then display calc. data. goto debugdata ; Else, display raw ADC data. goto userdata debugdata call cursorhome ; Reposition cursor to home. movlw A'A' ; Displays "ADRES0 xxx yyy" call PUTCHAR ; "ADRES1 xxx yyy" movlw A'D' call PUTCHAR movlw A'R' call PUTCHAR movlw A'E' call PUTCHAR movlw A'S' call PUTCHAR movlw A'0' call PUTCHAR movlw A' ' call PUTCHAR movf digittempdata2, w call PUTCHAR movf digittempdata1, w call PUTCHAR movf digittempdata0, w call PUTCHAR movlw A' ' call PUTCHAR movf digittempdataL2, w call PUTCHAR movf digittempdataL1, w call PUTCHAR movf digittempdataL0, w call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR call nextline movlw A'A' call PUTCHAR movlw A'D' call PUTCHAR movlw A'R' call PUTCHAR movlw A'E' call PUTCHAR movlw A'S' call PUTCHAR movlw A'1' call PUTCHAR movlw A' ' call PUTCHAR movf digitbritedata2, w call PUTCHAR movf digitbritedata1, w call PUTCHAR movf digitbritedata0, w call PUTCHAR movlw A' ' call PUTCHAR movf digitbritedataL2, w call PUTCHAR movf digitbritedataL1, w call PUTCHAR movf digitbritedataL0, w call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR goto displaydone userdata call cursorhome ; Reposition cursor to home. movlw A'T' ; Display message "Temp xxx.yy C" call PUTCHAR ; "Light xxx.yy %" movlw A'e' call PUTCHAR movlw A'm' call PUTCHAR movlw A'p' call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR movf tempnonfract2, w call PUTCHAR movf tempnonfract1, w call PUTCHAR movf tempnonfract0, w call PUTCHAR movlw A'.' call PUTCHAR movf tempfract1, w call PUTCHAR movf tempfract0, w call PUTCHAR movlw b'11011111' call PUTCHAR movlw A'C' call PUTCHAR call nextline movlw A'L' call PUTCHAR movlw A'i' call PUTCHAR movlw A'g' call PUTCHAR movlw A'h' call PUTCHAR movlw A't' call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR movlw A' ' call PUTCHAR movf britenonfract2, w call PUTCHAR movf britenonfract1, w call PUTCHAR movf britenonfract0, w call PUTCHAR movlw A'.' call PUTCHAR movf britefract1, w call PUTCHAR movf tempfract0, w call PUTCHAR movlw A' ' call PUTCHAR movlw A'%' call PUTCHAR displaydone return ;------------------------------------------------------------------------------------------------------------------------ ; End of Programme. ;------------------------------------------------------------------------------------------------------------------------ end