I am not sure if this warrants EE or PIC subject tags, but here goes...

I am building a hobby gadget around an 18F2321, it is running on
INTOSC+PLL for a 32MHz clock. My main UI element is a quadrature encoded
knob from BI Technologies (data sheet here
http://www.bitechnologies.com/pdfs/en11.pdf). From the datasheet there
appear to be 2 mechanical switches that connect to the common pin to
provide the output. I have grounded the common pin, and the two outputs
are connected directly to the RB0 and RB1 on the PIC. The weak pull ups
are turned on.

My original idea was to use INT0 as a movement indicator then read PORTB.1
(a TTL input) to determine direction. While this very accurately
determined rotation, the direction of rotation was very flaky with either
direction providing equally random results.

My guess at this point are that the switches are bouncing...

I did some googling to try and determine what I could do to help clean up
the signal. Most everything I have read shows a capacitor in parallel with
the switch, but without an actual value associated (I tried ~15nF without
any success). I have also read that a schmitt trigger will help, so I
switched to using INT1 with a mechanism to use INTEDG1 to store the pin
state, this wasn't much help either.

I am at a loss to what to try next, and hoping that the smart folks on
this list have some better ideas...

Anthony



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