What about GIE?  Shouldn't you be setting that as well?

-Neil.



-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Tim Daneliuk
Sent: Tuesday, June 04, 2002 4:27 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: RB0/INT Madness
Importance: High


I've got a 16F84A PIC circuit with nothing connected to PORTB at the moment.
I want to use RB0 as an interrupt as described in the docs but cannot seem
to get the thing to work.

Here is how I am initializing the hardware:

------------------------------------------------------------------------

init:
        clrf    INTCON                  ; all interrupts off, flags cleared

        ; setup control registers

        bsf     INTCON,T0IE             ; unmask TMR0 interrupts
        bsf     INTCON,INTE             ; unmask RB0 interrups

        bsf     STATUS,RP0              ; select register bank 1
        clrf    TRISA                   ; set PORTA to all outputs
        movlw   0ffh
        movwf   TRISB                   ; set PORTB to all inputs

        bsf     OPTION_REG,NOT_RBPU     ; no pullups
        bsf     OPTION_REG,INTEDG       ; RB0 interrupt on rising edge
        bcf     OPTION_REG,T0CS         ; TMR0 clocked on internal clock
        movlw   tmr0_pre                ; set TMR0 prescaler value
        iorwf   OPTION_REG,F
        bcf     STATUS,RP0              ; select register bank 0

        Blah, blah, blah, ...

--------------------------------------------------------------------------

Here is the relevant portion of the interrupt handler:

---------------------------------------------------------------------------


                org     04H

                movwf   _w              ; save context
                movfw   STATUS
                bcf     STATUS,RP1
                bcf     STATUS,RP0
                movwf   _status
                movfw   FSR
                movwf   _fsr
                movfw   PCLATH
                movwf   _pclath
                clrf    PCLATH

                ; Figure out who interrupted and service it

                btfsc   INTCON,T0IF     ; did we get a TMR0 interrupt?
                goto    svc_tmr0        ; yup
                btfsc   INTCON,INTF     ; did we get an RB0 interrupt?
                goto    svc_rb0int      ; yup
                goto    restore_context ; nope

                ; RB0 ISR

svc_rb0int:
                bcf     INTCON,INTF     ; clear the interrupt condition

      ********  WE NEVER SEEM TO GET HERE FOR SOME REASON **************

                goto    restore_context ; ISR done, return to main

                ; end of RB0 ISR


                ; TMR0 ISR
svc_tmr0:
                bcf     INTCON,T0IF     ; clear the interrupt condition

                Blah, blah, blah ...

----------------------------------------------------------------------------
-


I am trying to manually force the interrupt to check the interrupt handler
by
using a wire to connect RB0 to +5V (I realize this will bounce and do all
kinds
of noisy things), but, for some reason, the interrupt never seems to occur.
That is,
I never seem to get to the code contained in sv_rb0int:

Any ideas out there?
--
----------------------------------------------------------------------------
--
Tim Daneliuk
tundra@tundraware.com

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