>Can anybody advise me if they know of any successful efforts to use a PIC to
>interface to a rotary encoder to give a reading of angular resolution and
>direction.  I guess this would involve some sort of phase shift measurement.
>Any help would be very much appreciated.
>Regards  Kim Turner.


Kim,

I am using one and getting 2 million counts per revolution. If you don't
need that much resolution, you can do it pretty easily. Assuming your
encoder has two outputs, read them, then next time compare the new results
with the stored ones. If they are the same, no count. If they differ, xor
one of the new values(let's say bit 0) with the old value from the other
output(bit 1). If the result is 0 count one way. If you get 1, count the
other way. You'll get 4 times the number of lines on your encoder this way.
If you need more resolution from the same number of lines, you'll need to do
analog interpolation.

Cheers, Bob