> Good idea the cap and the resistor, that should kill much of the
> overshoot.. but wouldn't it be better another zener (this one
> connected to Vdd, not Vss) instead of the Schottky diode? I
> mean a two zeners solution, one zener to Vss and the other to
>Vdd

Wasn't "undershoot" the problem ? R+Z will limit V on the PIC
pin to 4V7, but adding another ZD to Vdd won't do anything to
stop sub-0V transitions. A zener has the same Vf as a normal
P-N diode (like the PIC's internal ones), whereas the Schottky's
metal-N composition has a lower Vf and will conduct first, which
is what you need

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