pic is 16f877. goto / define are picbasic. asm / endasm lets you do inline assembly with picbasic. i'm not sure
what you mean by "starting in position 1" with respect to the retfie instruction.  i've been told that the compiler
automatically saves w/status/pclath on pics over 2k, and inspection of the resulting assembler code confirms this
so i only need to restore them.

thanks !

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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>ways.  See http://www.piclist.com/#archives for details.
>
>--
>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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http://www.piclist.com hint: The PICList is archived three different
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