Just to ad more noise to the discussion, here's a solution that worked for
me on something similar.

Needed to input position settings via a small panel:

Used a small (cheap) rotary encoder (mechanical contact - no detents) made
by Bourne. Interfaced that to a Schmidt trigger mostly to get drive for a
one meter cable and have experienced no bounce problems. The switch does 6
cycles per revolution (24 edges) so if the contact bounce is as much as 5ms
(doubtful) you won't experience any problems unless you turn the knob at >
8 revs/sec. (I don't think so!) These encoders are stiff enough that they
don't drift when set.

NB: The only problem with contacting types is finite service life. The
problem with optical types is MONEY.

From the discussion so far, I get the impression you must be using a marked
bezzel to indicate position. Have you got the [pins, space,funds] for a 4x7
seg display. I found a decoder/display in Farnell's catalogue that uses a
serial interface over (min) 3 wires. The display is driven by the controller.

My application has range limits for input values as yours seems to, so I
simply ignore pulses which go to far. Your software should be doing that
anyway. The code I wrote dor decoding the 2 bit Gray code returns values
representing +1, -1, NoChange and WOOPS. The inputs use the "Interrupt on
Change" facility of a 16C84 and from memory the subroutine uses 2 static
and 2 dynamic bits in data memory and executes in about 23 clocks if memory
serves. Works for me...

Did I have 2 cents worth?
BILL


At 11:29 AM 8/01/98 -0600, you wrote:
>Sorry, not 16 controls on one panel.  up to 16 remote panels with a single
>knob each.  Each remote can select which motor he wants to control and it's
>speed as well as a few other things.  Each remote panel will have a PIC in
>it.
>
>The system has one base unit, up to 16 remotes that communicate with the
>base unit.  Yes it is for train control but the problem can be applied to
>many situations.
>
>Thanks for all the good ideas.  Even if I don't use them all here, they are
>definitly going into my archive for latter use.
>
>Norm
>