;================================================================================================ ; Date : 6 October 2007 ; Project : 7 Segment Thermometer ; Frequency : 4 MHz ; Device used : 16F877A ; Oscillator : XT ; Watchdog : OFF ; Copyright : ; Designed by : Mujahidin ; Comments : ; Dowloaded from Downloads www.iddhien.com ; The content information of this project is without waranty, you can free distribute any document ; in this project with still enclose the author name and the header title of this project. ;================================================================================================ LIST p=16F877 ;================================================================================================ w equ 0 ; working reg: f equ 1 ; same reg: ;================================================================================================ ; STATUS FLAGS ;================================================================================================ carry equ 0 zero equ 2 rp0 equ 5 ; bank selection rp1 equ 6 ;================================================================================================ ; SFR's - SPECIAL FUNCTIONS REGISTERS ;================================================================================================ indf equ 00 tmr0 equ 01 optionreg equ 01 ;bank 1 pcl equ 02 status equ 03 fsr equ 04 trisa equ 05h ; bank1 trisd equ 08h ; bank1 trisb equ 06h ; bank1 trise equ 09 ; bank1 trisc equ 07h ; bank 1 porta equ 05 portb equ 06 portc equ 07 portd equ 08 porte equ 09 pclath equ 0Ah intcon equ 0Bh tmr1l equ 0Eh tmr1h equ 0Fh pir1 equ 0Ch pie1 equ 0Ch ; other bank t1con equ 10h rcsta equ 18h txsta equ 18h ; other bank txreg equ 19h spbrg equ 19h ; other bank rcreg equ 1Ah adresl equ 1Eh ; Bank 1 adresh equ 1Eh adcon0 equ 1Fh adcon1 equ 1Fh ; other bank _WDT_OFF equ 3FFBh _XT_OSC equ 3FFDh ;================================================================================================ ; GPR - GENERAL PURPOSE REGISTERS area ;================================================================================================ CBLOCK 20h simage wimage digit1 digit2 digit3 ledindex delaysmall delaylarge delaytime resultlbyte resulthbyte tmrodelay count temp H_byte L_byte Treultlbyte Tresulthbyte TH_byte TL_byte R0 ; RAM Assignments R1 R2 ENDC ;================================================================================================ ; Constants & Declarations ;================================================================================================ gie equ 7 ; INTCON go equ 2 ; a/d conversion start/stop T0IF equ 2 ; timer0 overfow check flag ADON equ 0 ; switch on a/d converter. ;================================================================================================ ; DEFINE ;================================================================================================ ;configuration bits __CONFIG _XT_OSC & _WDT_OFF ;================================================================================================ ; RESET VECTOR ;================================================================================================ ORG 0 goto start ;================================================================================================ org 04 isr movwf wimage ; saving critical registers swapf status,w movwf simage movf H_byte,w movwf TH_byte ; these are also modified during isr, movf L_byte,w ; so have to be saved till next cycle. movwf TL_byte ;================================================================================================ ; IS routines goes here ;================================================================================================ decfsz tmrodelay,f ; wait for 16 interrupts to pass goto isrexit nop call atodcon ; on 16th interrupt,conversion. call atodforbcd movlw .16 movwf tmrodelay ; reinitialise the variable ;================================================================================================ isrexit ;================================================================================================ nop ; seems to be a timing violation nop ; so just a delay! bcf intcon,T0IF bsf intcon,gie movf TH_byte,w movwf H_byte movf TL_byte,w ; replace the registers, movwf L_byte ; clear the tmr0 flag caused bcf intcon,T0IF ; the interrupt. swapf simage,w movwf status swapf wimage,f swapf wimage,w retfie ;End of interrupt service routines ;================================================================================================ display_table addwf pcl,f ; W + PCL -> PCL retlw b'00111111' ; '0' retlw b'00000110' ; '1' retlw b'01011011' ; '2' retlw b'01001111' ; '3' retlw b'01100110' ; '4' table for segment patterns retlw b'01101101' ; '5' retlw b'01111101' ; '6' retlw b'00000111' ; '7' retlw b'01111111' ; '8' retlw b'01100111' ; '9' retlw b'10000000' ; '.' ;================================================================================================ ; SUBROIUTINES ;================================================================================================ display movlw b'00000001' ; select the left most digit movwf ledindex ; movwf porte ; digit selecting transistor on! movf digit1,w ; get the bcd value to display call digitout ; illuminate for a period rlf ledindex,f ; rotate to left to select next digit movf ledindex,w ; enable next digit movwf porte ; digit selecting transistor on! movf digit2,w ; get the bcd value. call digitout ; illuminate for a period rlf ledindex,f movf ledindex,w ; last digit selected. movwf porte movf digit3,w ; get bcd value call digitout ; illuminate for a period return ;================================================================================================ digitdelay movlw 5h ; outer loop for delay movwf delaylarge loopl decf delaylarge,f btfsc status,zero return movlw 0FFh movwf delaysmall loops decfsz delaysmall,f ; inner loop for delay goto loops goto loopl ;================================================================================================ digitout nop call display_table ; illuminate digit and wait movwf portd ; for some time call digitdelay clrf portd ; off the digit and return. clrf porte return ;================================================================================================ iniports bsf status,rp0 movlw b'00000001' ; input for analogue temp sensor movwf trisa ; RA0 as the input clrw movwf trisd ; all portd output for segments. movwf trise ; porte for digit selection bcf status,rp0 ; return to bank 0 and return clrf porta clrf portd clrf porte return ;================================================================================================ iniatod bsf status,rp0 movlw b'10001110' ; result right justified ,ra0 as movwf adcon1 ; analogue input with Vdd as Vref bcf status,rp0 movlw b'01000000' ; a/d clock Tosc*8 and Ra0 channel movwf adcon0 ; selected. a/d module still off. return ;================================================================================================ initimer bsf status,rp0 ; bank 1 movlw b'10000111' ; timer0 on internal clock pulse movwf optionreg ; prescaler 1:256 movlw b'10100000' ; gie and TMR0 interrupt enabled movwf intcon ; all ready! bcf status,rp0 movlw .1 movwf tmrodelay ; initialise the delay variable to return ; start conversion on 1st interrupt ;================================================================================================ atodcon bsf adcon0,ADON ; swich on a/d converter. movlw 0Ah movwf delaytime aquiloop decfsz delaytime,f ; wait for aqusition time. goto aquiloop bsf adcon0,go ; conversion starts now! converloop btfsc adcon0,go ; loop until conversion complete. goto converloop bsf status,rp0 ; bank for adresl movf adresl,w ; low byte of result. bcf status,rp0 movwf resultlbyte ; a/d low byte saved movf adresh,w ; high byte of result movwf resulthbyte ; a/d high byte saved return ;================================================================================================ B2_BCD bcf status,0 ; clear the carry bit movlw .16 movwf count clrf R0 clrf R1 clrf R2 loop16 rlf L_byte, f rlf H_byte, f rlf R2, f rlf R1, f rlf R0, f ; decfsz count, f ; routine for bcd conversion goto adjDEC retlw 0 ; adjDEC movlw R2 movwf fsr call adjBCD ; no bank switching, always ; ; indirect access for RAM movlw R1 movwf fsr call adjBCD ; movlw R0 movwf fsr call adjBCD ; goto loop16 ; adjBCD movlw 3 addwf 0,W movwf temp btfsc temp,3 ; test if result > 7 movwf indf movlw 30 addwf 0,W movwf temp btfsc temp,7 ; test if result > 7 movwf indf ; save as MSD retlw 0 ;================================================================================================ ; Arrange the result as digits 1,2,3. bcdsplit movf R1,w ; bring first nibble andlw 0Fh ; mask the upper nibble movwf digit1 ; send to display routine variable. movf R2,w ; bring the second digit! andlw 0F0h ; mask the lower nibble. movwf digit2 ; send to display routine variable. swapf digit2,f ; after swaping! movf R2,w ; Again bring the lowbyte andlw 0Fh ; mask the upper nibble movwf digit3 ; send it to display routine variable return ;================================================================================================ atodforbcd rrf resultlbyte,f ; routine for dividing the value bcf status,carry rrf resulthbyte,f btfsc status,carry bsf resultlbyte,7 ; xxx movf resultlbyte,w ; movwf L_byte ; bcd conversion subroutine. movf resulthbyte,w ; movwf H_byte ; return ;================================================================================================ ; Main program starts ;================================================================================================ start clrf simage clrf wimage clrf digit1 clrf digit2 clrf digit3 clrf ledindex clrf delaysmall clrf delaylarge clrf porta clrf portd clrf porte bsf status,rp0 clrf trisd clrf trisb clrf trisc clrf trise clrf trisa bcf status,rp0 bcf status,rp1 call iniports ; initialise all relevent ports. call iniatod ; initialise a/d converter module. call initimer ; initialise timer0 so to derive a time base. ;================================================================================================ main ;call atodcon ; conversion and result saved. ;call atodforbcd ; result moved for bcd conversion call xxx call B2_BCD ; bcd conversion call bcdsplit ; seperate nibbles for digits call display ; display the digits. goto main ;================================================================================================ END