> if your
> 'low speed' signal has fast rise and fall times you may have to slow them
> down in order to avoid odd effects.

The way it is set up, the switches at the far end of the cable are a rotary
switch with one always grounding an input pin and the others just floating,
letting the pull up on the board keep the inputs high.  So the rise and fall
times are the result of someone rotating the switch and grounding another
pin from remote.

> the switch could dump a 50ma current for a short time (nanoseconds). If
the
> edge of the pulse is not attenuated when it gets to the PIC the pin would
> try to go to -5v, and suck that 50ma through the protection diode until
the
> line settles.

If I have a resistance in series with the pic input and then do everything
else from that resistor, like adding the pull up at that point for a
resistance of the pull up plus the serial R, and then a capacitor from that
same R junction to ground, does this adequately arm me for attenuation and
slowdown?

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