The decoder I used (Bournes) had a specified contact bounce time of 5 ms.
That was a good reason not to connect it a an interupt pin!  Seriously I did
think about thihs method and was warned against it by someone else on the
list becuase of this.  I guess if you are using a super optical encoder with
no bounce it would be ok.

Regards

Mike Rigby-Jones



> -----Original Message-----
> From: &lt Patric Anvegard [SMTP:patric.anvegard@ARCOMA.SE]
> Sent: Tuesday, April 20, 1999 1:10 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: Quadrature decoder
> 
> Hi everybody!
> 
> Thanks for the good advises to solve my problem with the quadrature
> decoding.
> I'll try some of the routines I got from Walter Banks and Alvaro and see
> how they work...
> 
> The solution that I had some thoughts about before I sent this message to
> the list
> was that this problem could be solved by having one of the channels(A)
> connected
> to the Capture input and the other one to an "ordinary" input.
> The Capture module is initialized to interrupt on rising edge. When I get
> an interrupt I
> put the processor in "state 1" if the B-channel is 1 or in "state 0" if
> the B-channel is 0
> and when changes the CCP module to interrupt on falling edge.
> When I get the next interrupt I read the B channel and detects the
> direction. If the
>  previous state was 0 I should now get a 1 on the B-channel or if the
> previous state was 0 I should now get a 0. If I get two 0 states (or two 1
> states) I ignore it (this could
>  accure if I get noise on the A channel or if the direction has changed on
> the encoder. 
> 
> Does anyone have an argument why this should'nt work or should I put some
> effort to try this solution too.
> 
> Patric AnvegŒrd