I am trying to measure 3 capacitors being used as sensors on PortA.0 to PortA.2 on a 16F887, using POT.
The resistor is 10K, capacitor varies from .1 uf down to perhaps 0.01.
I'm sure I've set all the pins as digital, ADCs, comparators disabled, no schmitt input pins used.
While individually each channel seems to work fine, great repeatability, the readings for the same capacitor on different channel is significantly different.
Just to rule out something specific to PortA that I might have missed, I tried this on other sets of pins, with the same result.
My question is, is this normal?
I'm getting frustrated enough to consider using 3 external CMOS 555s (with 'C' as the unknown capaitor) as oscillators, with the pic just reading the pulses. But I'm still hoping this could be done without any external chips.
Any suggestions, folks?
Regards,
Anand
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