Fabiano,

Try this
     org     20h
Table1
>    movwf temp
>   movlw HIGH $
>  movwf pclath
>  movf temp,w

      addwf   PCL,F
      retlw   B'00001110'  ; line 0x0000
      retlw   B'00010001'  ; line 0x0001
      retlw   B'00010001'  ; line 0x0002
      retlw   B'00010001'  ; line 0x0003

Pailoor

Fabiano Leitao wrote:

> Hello, people.
>
> I want to implement a table look-up for a P16C74A. This table is called by
> another routine placed at 0x200. As the table is large and  crosses the 256
> bytes page boudary, I used the piece of code suggested by the application
> note AN556, in order to allow me to place the table anywhere in program
> memory. Please , see the code below:
>
>      org     00
>      goto    Main
>
>      org     04h
>      goto    inter
>          .
>          .
>      org     20h
> Table1
>       addwf   PCL,F
>       retlw   B'00001110'  ; line 0x0000
>       retlw   B'00010001'  ; line 0x0001
>       retlw   B'00010001'  ; line 0x0002
>       retlw   B'00010001'  ; line 0x0003
>          .
>          .
>       retlw   B'00011111'  ; linha 0x00fd
>       retlw   B'00010001'  ; linha 0x00fe
>       retlw   B'00010001'  ; linha 0x00ff
>       retlw   B'00011110'  ; linha 0x0100
>       retlw   B'00010001'  ; linha 0x0101
>       retlw   B'00010001'  ; linha 0x010f
>          .
>          .
>       retlw   B'00010001'  ; linha 0x011f
>       retlw   B'00010001'  ; linha 0x0120
>
>       org      0x 0200
> Call_table
>       ; do a lot of things here
>         .
>         .
>       movlw    LOW  Table1      ; AN556  suggestion
>       addwf    offset_Table1
>       movlw    HIGH Table1
>       btfsc    STATUS,C
>       addlw    1
>       movwf    PCLATH
>       movf     offset_Table1,w
>       call     Table1
>         .
>         .
>       return
>
>       org      0x0300
> Main
>       .
>       .
>    call   Call _table
>       .
>       .
> end
>
> Well, the fact is that the return codes from the table calls are not
> correct, and for some offset values given to the table, the PIC "crashes".
> I suspect that the jump to the table routine is not OK.
>
> Could anyone help me ?
>
> This is my first message to this list. I expect to give many contributions
> to everybody in the future.
>
> Thanks in advance.
>
> Fabiano O.L.
>
> ______________________________________________________
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--
Website : http://business.vsnl.com/chiptech


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