aha .. might be getting somewhere. i figured out what you mean by RETFIE in position one. i moved it and program
quit working all together, but that's progress. i think i'm heading in right direction :)

thanks jan-erik


dld

On Fri, 26 Sep 2003 22:41:28 +0200, Jan-Erik Soderholm XA (TN/PAC) wrote:

>What language/tool ?
>What PIC type ?
>What is this "GOTO" and "DEFINE" ? Doesn't look as MPASM !?
>What is "asm" and "endasm" ?
>Why is only the retfie instruction starting in pos 1 ?
>Why restore w, status and pclath if you don't save them ?
>
>Jan-Erik
>
>
>
>-----Original Message-----
>From: David Dunn [mailto:ddunn@TCAINTERNET.COM]
>Sent: den 26 september 2003 22:02
>To: PICLIST@MITVMA.MIT.EDU
>Subject: [PIC]: Interrupts
>
>
>I'm at wits end here, for some reason my ISR doesn't seem to be working. I'm monitoring '_TENTHS' in the main
>program loop and it's not incrementing.  Have I missed something obvious ?  What kinds of things would keep the
>TIMER0 interrupt from running ?
>
>Thanks for any ideas.
>
>
>DLD
>
>--------------------------------------------------------------------------------------------------------------
>
>
>wsave           var     BYTE    $020 SYSTEM
>wsave1  var     BYTE    $0a0 SYSTEM
>wsave2  var     BYTE    $120 SYSTEM
>wsave3  var     BYTE    $1a0 SYSTEM
>ssave           var     BYTE    BANK0 SYSTEM
>psave           var     BYTE    BANK0 SYSTEM
>
>GOTO AFTERINT                              'Jump past interrupt handler
>
>DEFINE INTHAND isr
>
>asm
>
>isr                             ; int handler begins here
>
>    ;bsf     portb,7
>
>    btfsc   INTCON,1            ; test if external interrupt (portb.0) occurred
>    goto    portbint            ; jump over to (portb.0) int handler. otherwise, just fall thru to TIMER0 handler
>
>timer0int
>
>    movlw       0x9e                        ;reload timer with (256 - (1)200) + 2 (3a for .1, 9e for .05)
>    movwf       TMR0
>    incf        _TENTHS                 ;increase TENTHS value
>    bcf         INTCON,2                    ;clear tmr0 interrupt flag
>    goto    exitisr
>
>portbint
>
>    movf    TMR1H,W            ;read value on timer1
>    movwf   _TMR1HI            ;store it in some variable
>    movf    TMR1L,W
>    movwf   _TMR1LO
>
>    clrf    TMR1L              ;load timer1 with zero again
>    clrf    TMR1H
>
>    bcf         INTCON,1                    ;clear rb0 interrupt flag
>
>exitisr
>                                ;restorecode follows here
>        movf    psave,w
>        movwf   PCLATH
>        swapf   ssave,w
>        movwf   STATUS
>        swapf   wsave,f
>        swapf   wsave,w
>
>retfie
>
>endasm
>
>AFTERINT:
>
>    ' set up timer0
>    TMR0        = 0
>    INTCON      = %00000000
>    OPTION_REG  = %11000111
>    INTCON      = %10100000
>
>--
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>
>--
>http://www.piclist.com hint: The PICList is archived three different
>ways.  See http://www.piclist.com/#archives for details.


David Dunn
Digital Racing Products

dave@digitalracingproducts.com
www.digitalracingproducts.com

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