Jeff 'n Kristen Kroll wrote:
>
>         I have been reading the PICLIST for about a month and have seen
 several
> methods of doing quadrature decoding on a PIC. One method, the one in the
> Microchip Applications Handbook suggests monitoring one channel and when it
> changes check the other channel to determine direction. Doesn't this reduce
> the resolution of the encoder by half?
Yes it does.

> This method would be great if it
> didn't because the project I am working on, a six degree of freedom
> trackball, needs to monitor three encoders, and the 16c65 chip I'm using
> only has four interrupt on change pins. However I can't sacrifice
> resolution.

Another way is to sample the port with a timer set to the fastest
expected quadrature speed it will have a lower interrupt overhead
and full resolution. The code on a PIC is quite abit shorter.

Walter Banks.