Hi Glen,
I can't follow your code, It wraps around and the formatting
makes it hard to read.  But what little I can decipher I don't
understand what you are trying to do with the "xorwf chksw"

what you have looks like....

caltab
        CALL    table   ; use look up table
        MOVWF   strttmr ; move value from table to strttmr
        XORWF   chksw   ; compare chksw value (switch value)
        BZ      caltab

table
        ADDWF   PCL,f   ; sw value : time :
        RETLW   d'25'   ; 00    : 250ms (switch
        RETLW   d'50'   ; 01    : 500ms (switch
        RETLW   d'75'   ; 10    : 750ms (switch
        RETLW   d'100'  ; 11    : 1000ms (switch

What this will do is as follows, first time correct
lookup value will be returned, and the table will
be re-entered with the return value instead of the
switch value, this will result in a jump past the
end of the table with unpredictable results! :-(

I would suggest the following.

1. Get the hardware working correctly first, you
might have to put a pull down on RB3.

2. Constrain W as follows
table   ANDLW   0x03    ;
        ADDWF   PCL,f   ; sw value : time :
        RETLW   d'25'   ; 00    : 250ms (switch
        RETLW   d'50'   ; 01    : 500ms (switch
        RETLW   d'75'   ; 10    : 750ms (switch
        RETLW   d'100'  ; 11    : 1000ms (switch

3. Check for TMR0 overflow flag rather than looking
at the timer value directly. Better yet handle the
TMR0 overflow in an interrupt.

==============[ original message ]================

>hi & sorry again !
>i don't know how to get around this problem !!
>i still can't get the table to work properly !
>
>the table puts the first value into strttmr regardless of the switch
>settings
>
>**how do i get the switch settings value to access the corresponding
>value
>in the lookup table & place it into strttmr? ***
>
>eg     switch setting = 1 0  (rb0 = 1 , rb1 = 0 )
>table value at 10 = d'75'
>put d'75' into strttmr
>the problem area is in the section 'select switch setup '
>;************************ports setup****************************
>;**********************************************************************
>         clrf              STATUS
>;============= prescaler setup ===pullups enabled===========
>         movlw         b'00000111'         ;scale 1:256 , pullups
>enabled
>         OPTION
>;**********************************************************************
>;**********************************************************************
>; ============= select switch setup ==============
> ;code below is used for 2 switches
> ; init strttmr from input pins
>         movf        PORTB,w          ;get values of RB0 & RB1
>         andlw     0x03             ; extract out bits 0,1 of PORTB
>(table sw value)
>         movwf     chksw             ;put rb0 & rb1 values in register
>chksw
>
>caltab CALL     table                 ; use look up table
>         movwf     strttmr             ;move selected value from table
>to strttmr
>         xorwf       chksw              ;compare with chksw value
>(switch value)
>         btfsc         STATUS,Z         ;if same , skip next instruction
>
>         GOTO     caltab
>;******************TABLE TO GO IN SUB ROUTINES***********************
>table addwf         PCL,f            ;sw value : time :
>         retlw         d'25'               ; 00         : 250ms (switch
>position 1)
>         retlw         d'50'               ; 01         : 500ms (switch
>position 2)
>         retlw         d'75'               ; 10         : 750ms (switch
>position 3)
>         retlw         d'100'             ; 11         : 1000ms (switch
>position 4)
>;**********************************************************************
>;**********************************************************************
>;       ============== program start =============
>        movlw         0x00              ;move 00 hex to register w
>         movwf         PORTB             ;move register w to PORTB
>(clear PORTB)
>;============= prescaler setup ===pullups disabled===========
>         movlw         b'10000111'         ;scale 1:256 , pullups
>disabled
>         OPTION
>; ============= initialise timer setup ==============
>initmr movlw         .215          ;40 * .000256 = 10 ms
>         movwf         TMR0
>
>loop CALL         chcycs    ;check for zero crossing
>         CALL         sttimer    ;call initial time delay
>         CALL          tog        ;toggle outputs
>; ============= check timer ==============
>         movf             TMR0,w          ;move f reg to w
>         btfsc             STATUS,Z         ;if !0 ,GOTO loop
>         GOTO          loop
>         decfsz             strttmr,f             ;decrement strttmr by
>1
>         GOTO             initmr              ;go around for next delay
>
> ;drop thru to stop
>stop GOTO             stop
>;======================delay sub-routines=======================
>;
>    end
>
>thanks very much for your help because i'm LOST !!
>glen


Ray Gardiner ray@hdc.com.au