> a capacitor in parallel with the switch, but without an actual value
> associated (I tried ~15nF without any success)

Anthony,

At the high end of spec, 400uA, the weak pull-up current equates
to a resistor of 14k ohms

I typically use 100k + 100nF on pushbuttons, which smoothes
most of the higher frequencies out, then follow that up with polling
in s/w

An RC filter will work, you just need to find values that suit your
response requirements. eg big R and big C will be an effective but
slow integrator

You can use INT0 / INT1 IRQ to detect the initial change in
condition on the pin when the switch first closes and until you've
done with processing the switch it can be, or remain, turned off

So, for example, you'd enable INTx interrupts to detect either
switch closure and have an ISR to clear the INTxIF. You don't
have to exit the ISR with RETFIE. If you exit it with RETURN
(all) interrupts will remain off - as they're turned off on ISR entry -
and you can re-enable INTx at your convenience

A plain Schmitt Trigger has limited value as a filter. In a noisy
environment like a bouncy contact it will pass transitions outside
of the threshold window

HTH

Joe
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