Lou Calkins wrote:

> Hi Lee -
>
> I am not an expert on the PCLATH register, but I have had some very
> unpleasant experiences because of it (rather because of my lack of knowledge
> of it).  I will try to respond to some of your questions the best I can.
>

What I do when I use a look-up table:

;=============================LOOKUP TABLE================
LOOKUP  MOVLW   HIGH    BASEADD ;LOAD HIGH BYTE OF BASE ADDRESS INTO W
        MOVWF   PCLATH          ;HIGH BASEADD INTO PC-LATCH
        MOVLW   LOW     BASEADD ;LOAD LOW BYTE OF BASE ADDRESS INTO W
        ADDWF   VALUE,W         ;ADD OFFSET TO PC LOW
        BTFSC   STATUS,C        ;TEST FOR ROLL-OVER IN PC <-- this is the
significant part!
        INCF    PCLATH          ;INCREMENT PCLATH IF ROLL-OVER DETECTED <-- So's
this!
        MOVWF   PCL             ;LOW BASEADD INTO PCL

BASEADD RETLW   B'10000100'     ;0
        RETLW   B'10101111'     ;1
        RETLW   B'11001000'     ;2
        RETLW   B'10001001'     ;3
        RETLW   B'10100011'     ;4
        RETLW   B'10010001'     ;5
        RETLW   B'10010000'     ;6
        RETLW   B'10001111'     ;7
        RETLW   B'10000000'     ;8
        RETLW   B'10000001'     ;9

See pretty easy! I didn't think this out myself though. My lecturer at
Tech showed us the light....

Cheers... and good luck!

--
Eric van Es               | Cape Town, South Africa
mailto:vanes@ilink.nis.za | http://www.nis.za/~vanes
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