>
> But I still don't understand this.  Is the capacitor discharging
> thru the PIC pin or thru the leg of the pot to ground?  If it's the PIC pin,

I believe the answer is both.

It is my understanding that the bulk of the discharge is through the leg
to the ground. Obviously a bit of the discharge is going through the pic
(to knock the pin high) but it's a high-impedance input... so only
enough current to keep the pin high and the rest goes through the pot.

The result is that the pic acts as a "monitor" of the voltage going past
it. The pic pin has a trigger that stays high until the voltage drops
below a particular point, so even as the voltage is dropping past 5, it
stays high for a little while.

While this works well to get a rough idea of the value of the pot or
light levels with a photoresistor it is not exactly accurate, which is
why true A-D conversion is preferable in some cases.

My explanation is mathematically poor, but my understanding is that
there are too many variables (including precise threshold at which the
pin reads low, ambient temperature, etc.) with RCTime to really figure
it out, which might explain your results.

Anyone else?