Nicholas wrote:

>>Hi all,
>>
>>I need to use even parity, 1 stop bit with 7 data bits.  I can quite
>>easily transmit 8 data bits and no parity but my question is "what
would
>>be the best way of implementing even parity and 7 data bits."  Has
>>anybody got a snippet of code I could look at (or even pseudo code) or
>>maybe a web site to goto?
>>
>>Thanks for any advise,
>>Brian.
>
>I'm sure some people have some optimised algorithms out there but
>one usefull thing to remember is that XOR can be looked at as a
>1 bit add applied in parallel (ie 8 times) to each bit in the byte
>Thus by shifting bits and swapping nibbles you can arrange to calculate
>the parity which is just the sum of all bits.
>
>; enter with data in W exits with parity in bit 7 of W
>temp            equ Scratch_Register
>                movwf temp
>                swapf temp,F
>                xorf temp,F
>                rlf temp,F
>                rlf temp,F
>                xorf temp,W
>                movwf temp
>                rlf temp,F
>                xorf temp,W


Nicholas,
 I couldn't get this to work.  Will it work on a 16C74?  What does the
line xorf temp,W mean...   do you mean xorwf temp,W?  If you did, I still
can't see it working.

Thanks,
Brian.