On 7/23/05, Augusto Yipmantin <spam_OUTaugustoyTakeThisOuT
centaurocomunicaciones.com> wrote:
>
> 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.
Almost impossible, a battery is the cleanest power supply ever
possible. Only if you are supplying also some automotive circuits
which are generating huge spikes (coils. etc) Check your software
first.
{Quote hidden}>
> 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
>
>
> --
