PICers,
I'm using a 16F84 to play an ISD chip. It goes from the start (org
$00) to "look" then polls for a memory overflow then replays and
cycles back to "look"

Works fine when the interrupt is disabled.

BUT when I enable the interrupt, it starts to play then goes into the
ISR then tries
to play then back to ISR etc etc. Er ... needless to say I'm NOT
giving it an interrupt while this is happening  :(

So what's going on?  I notice there's a grey box+code frag on page 31
of the data sheet.
OK maybe the WDT is somehow generating an interrupt. I have the WDT
turned OFF in the
CONFIG instruc right at the start.

I called the following subr in the initialisation stage :-
TIMER0_WDT      ;As per page 31
        BANK_0
        clrf    TMR0
        BANK_1
        clrwdt
        movlw   b'00000000'
        movwf   OPTION_REG
        BANK_0
        retlw   0x00

But same symptoms. TMR0 & OPTION_REG change as the programme cycles in
the LOOK loop.

Where would you insert that code snip - in the loop, in the
initialisation stage or what? IF that's the problem that is? What's it
do anyway?

Any insights MUCH appreciated - Ian



         org       0x04
intrpt   movwf     w_             ;Start interrupt routine
         movf      STATUS,0
         movwf     STATUS_
         movf      PCLATH,0       ;Save PCLATH
         movwf     PCLATH_
         movf      FSR,0
         movwf     FSR_
brk00    ;INTERRUPT SERVICE ROUTINE GOES HERE

int_ret  movlw     b'00011000'    ;Reset the INTCON bits BUT ...
         movwf     INTCON         ;.. let the PIC set GIE upon retfie
         movf      FSR_,0
         movwf     FSR
         movf      PCLATH_
         movwf     PCLATH
         movf      STATUS_,0      ;Return from interrupt
         movwf     STATUS
         swapf     w_             ;Flip & load the w register
         swapf     w_,w           ;without affecting the STATUS reg.
         retfie


;MAIN PROGRAMME .. ENABLE INTERRUPTS THEN PLAY THE ISD

setint  nop                   ;Get ready to enable the interrupts
        BANK_1
        movlw  0x0D
        movwf  OPTION_REG
        BANK_0
        clrf   TMR0
        movlw  b'10011000'    ;Enable the interrupts
        movwf  INTCON

look   ;THE MAIN PROCESS GOES HERE.
       ;CYCLE AROUND .. PLAY THE ISD, LOOK FOR MEM OVERFLOW THEN
REPLAY ETC.
        goto    look






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