wow, thanks, that was quick:)
For current code I jus added masking off first 4 bits of PICLSB after
last shifting, instead of before shifting. Now it works correctly.


On 5/21/07, Bob Barr <bbarr@california.com> wrote:
> On Mon, 21 May 2007 19:27:51 +0300, KPL wrote:
>
> <snip>
> >Here is part of the asm, for beginning I am reading only full degrees,
> >so i take both data bytes, shift them 4 bits to leave integer only,
> >and then decode and show it on old LED ascii display HDLU-1414.
> >Program is based on routines from maxim application note 2420.
> >May be somebody can see the error:)
> >
>
> One possibility for a problem come to mind:
>
> Before doing those 4 'rlf' instructions on PICLSB, you should ensure
> the the carry bit is cleared by using the pseudo-op 'clrc'.
>
> If the carry bit is set before those instructions are executed, bit 3
> of PICLSB will be set when you don't expect it to be.
>
> Regards, Bob
>
>
> <snip>
>
> >       rrf     PICMSB,F
> >       rrf     PICMSB,F
> >       rrf     PICMSB,F
> >       rrf     PICMSB,F        ;shift 4 bits R
> >       movlw   15              ;mask for 4 bits
> >       andwf   PICMSB,F        ;leaving 4 bits
> >       andwf   PICLSB,F        ;leaving 4 bits
> >       rlf     PICLSB,F
> >       rlf     PICLSB,F
> >       rlf     PICLSB,F
> >       rlf     PICLSB,F        ;shift 4 bits left
> >       movfw   PICLSB
> >       xorwf   PICMSB,W        ;join both bytes
> >
> >       movwf   BIN
> >       call BIN2BCD
> >
> >       bcf     testout
> >       call    hpdl_out
> >       call delay
> >goto   req_conv
> >
> >
> >
> >--
> >KPL
>
> --
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-- 
KPL
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