Dear Vasile,

You are right; the potentiometer is wired as a divisor with the center
pin wired to the AN0 and AN1 pins (two potentiometers I am using, one
for each pin).

The circuit is mounted in a proto board and the supply is a 12V@8Ah
battery, so the origin of the noise maybe will be from the wiring.

I will check the reference voltage.

Regards,

Augusto


Vasile wrote:

  Not the potmeter is the problem but how much noise there is on the
supply voltage.
I'm expecting you've wired the potentiometer as a divizor with the
center pin (wiper) to the analogic imputs. Check out the noise on the
VCC using a scope or a DMM with high resolution and see how many
readouts can you see on the last digit (which is moving around a
center value up and down). With a scope will be better, but doubts you
have one.
 Filter the reference voltage in the potentiometer input using an RC
with a time delay of 10-100mS. A 47nF to 100nF on the analogic pins to
ground, may help too but decrease the time response of the circuit.
  Wrong wired grounds also alter the results on AD. To small Tad
(aquisition time) or messy readings on bank1 could gave you the same
situation.

dig on,
Vasile


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