seven segment 3 digit counter

Pommie said:

The code looks fine. When you say it's not working, what is it doing?

One thing, which is not your problem but may cause problems later, the temporary variables (w_temp etc) need to be in the common area at 0x70 - 0x7f.

Mike.
For anyone interested, here is the tidied up version.

Code:

;7 segment LED display - count up from zero

        LIST    p=16F877a    ;tell assembler what chip we are using
include        "P16F877a.inc"         ;include the defaults for the chip
        ERRORLEVEL 0,-302    ;suppress bank selection messages



        cblock    0x20        ;start of general purpose registers
count                    ;used in looping routines
count1                    ;used in delay routine
counta                    ;used in delay routine
countb                    ;used in delay routine
tmp1                    ;temporary storage
tmp2
p_temp                    ;save register
s_temp                    ;save register
w_temp                    ;save register
tens                    ;tens storage
ones                    ;ones storage
        endc

SEG_PORT    Equ    PORTB        ;7 segment port
SEG_TRIS    Equ    TRISB


        org    0x0000
        goto    Initialise

;************************************************* *************************   
;     Interrupt routine
;************************************************* *************************



; Interrupt routine handles TMR2 which generates a 1ms tick

;    Interrupt vector

        ORG    0x0004


INT
        movwf    w_temp        ; Save W register
        swapf    STATUS,W    ; Swap status to be saved into W
        movwf    s_temp        ; Save STATUS register
        movfw    PCLATH
        movwf    p_temp        ; Save PCLATH

        btfss    PIR1,TMR2IF    ; Flag set if TMR2 interrupt
        goto    INTX        ; Jump if not timed out

; Timer (TMR2) timeout every 1 milli second


        bcf    PIR1,TMR2IF    ; Clear the calling flag


        btfss    SEG_PORT,7    ;check which LED was last
        goto    Do_tens
        movfw    ones
        andlw    0x0F        ;make sure in range of table
        call    LED_Table
        andlw    0x7F        ;set to correct LED
        movwf    SEG_PORT
        goto    INTX

Do_tens        movfw    tens
        andlw    0x0F        ;make sure in range of table
        call    LED_Table
        iorlw    0x80        ;set to correct LED
        movwf    SEG_PORT



INTX
        movfw    p_temp
        movwf    PCLATH        ; Restore PCLATH
        swapf    s_temp,W
        movwf    STATUS        ; Restore STATUS register - restores bank
        swapf    w_temp,F
        swapf    w_temp,W    ; Restore W register
        retfie

LED_Table    ADDWF    PCL , f
        RETLW    b'10001000'    ;0
        RETLW    b'10111011'    ;1
        RETLW    b'11000001'    ;2
        RETLW    b'10010001'    ;3
        RETLW    b'10110010'    ;4
        RETLW    b'10010100'    ;5
        RETLW    b'10000100'    ;6
        RETLW    b'10111001'    ;7
        RETLW    b'10000000'    ;8
        RETLW    b'10110000'    ;9
        RETLW    b'11111111'    ;blank
        RETLW    b'11111111'    ;blank
        RETLW    b'11111111'    ;blank
        RETLW    b'11111111'    ;blank
        RETLW    b'11111111'    ;blank
        RETLW    b'11111111'    ;blank


Initialise    movlw    0x07
        movwf    CMCON        ;turn comparators off (make it like a 16F84)
        bsf    STATUS,RP0    ;select bank 1
        movlw    b'00000000'    ;Set port data directions, data output
        movwf    SEG_TRIS
        bcf    STATUS,RP0    ;select bank 0


;    Set up Timer 2.

;movlw    b'01111110'     ; Post scale /16, pre scale /16, TMR2 ON
;uncomment previous line, and comment next line, to slow multiplexing speed
;so you can see the multiplexing happening
        movlw    b'00010110'    ; Post scale /4, pre scale /16, TMR2 ON
        movwf    T2CON

        bsf    STATUS,RP0    ;select bank 1

        movlw    .249        ; Set up comparator
        movwf    PR2

        bsf    PIE1,TMR2IE    ; Enable TMR2 interrupt

        bcf    STATUS,RP0    ;select bank 0

; Global interrupt enable

        bsf    INTCON,PEIE    ; Enable all peripheral interrupts
        bsf    INTCON,GIE    ; Global interrupt enable

        bcf    STATUS,RP0    ;select bank 0

        clrf    tens
        clrf    ones



Main
        call    Delay255
        call    Delay255
        call    Delay255
        call    Delay255
        incf    ones,    f
        movf    ones,w        ;test first digit
        sublw    0x0A
        btfss    STATUS, Z
        goto    Main
        clrf    ones
        incf    tens,    f
        movf    tens,w        ;test second digit
        sublw    0x0A
        btfss    STATUS, Z
        goto    Main
        clrf    tens
        goto    Main        ;loop for ever


Delay255    movlw    0xff        ;delay 255 mS
        goto    d0
Delay100    movlw    d'100'        ;delay 100mS
        goto    d0
Delay50        movlw    d'50'        ;delay 50mS
        goto    d0
Delay20        movlw    d'20'        ;delay 20mS
        goto    d0
Delay5        movlw    0x05        ;delay 5.000 ms (4 MHz clock)
d0        movwf    count1
d1        movlw    0xC7        ;delay 1mS
        movwf    counta
        movlw    0x01
        movwf    countb
Delay_0
        decfsz    counta, f
        goto    $+2
        decfsz    countb, f
        goto    Delay_0

        decfsz    count1    ,f
        goto    d1
        retlw    0x00

Click to expand...