> From: Brad Turnert <bturner@ENTERPRISE.POWERUP.COM.AU>
>
> 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.
>

Many rotary encoders use quadrature encoding i.e. two square wave signals either
+90 or -90 degrees out of phase depending on direction.  The encoder will often
condition the signal into TTL levels.  If not, you will need to add comparators
to square up the signals.

Perhaps the easiest way to read these signals is to use the interrupt-on-change
facility of the PIC.  The PIC should be able to keep up with quite fast
rotation e.g. several thousand RPM with a 1024 count-per-rev wheel.

Regards,
SJH
Canberra, Australia

PS I'm off to the Barossa Valley for a few weeks so take care!