From my experience you must turn the intcon_gie off at the begining of the
interrupt and not in the main. Else multiple interrupts may occure.
Also you don't need to set intcon_gie on in the main because retfie do
this job when you go out from ISR
Vasile

On Wed, 7 Feb 2001, info wrote:

> Hi gang
>
> Having a little Interrupt problems with the f877. 2 days and counting ):
> I am using an ice2000 now to try and debug the problem with no joy.
>
> Basically the GIE bit keeps turning itself off randomly and locking the
> code. here is a simplified version of the code. Nops replace the main
> program parts to simplify.
> -------------------------------
> interupt routine
>         save context                    ;obvious
>         btfsc   PIR1,TMR1IF             ;tmr1 int
>         goto    timer1overflow
>
>         other interupt stuff
>         restore context
>         retfie
> timer1overflow
>         bsf     overflowflag            ;set tmr1 interupt flag
>         restore context
>         retfie
> -------------------------------
> START
>         set ports and normal stuff
>         set up interupts
>         BSF INTCON,GIE
>
> MAIN    bcf     INTCON,GIE              ;turn ints off
>         nop
>         check for external signal w     ;part of my code
>         nop
>         bsf     INTCON,GIE              ;turn ints on
>         nop
>         call loop                       ;call sub
>         goto    MAIN                    ;go again
>
> loop    nop
>         nop
>         btfss   timer1overflowflag      ;has tmr1 int
>         goto    loop                    ;repeat loop
>         bcf     timer1overflowflag      ;clr flag
>         return                          ;end sub
> -----------------------------------
> The program gets stuck in the loop when the GIE bit seems to randomly
> clear itself??????? Any ideas
>
> Scott
>
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