POT jitter on ADC???

Batz Goodfortune batzman at all-electric.com
Wed Feb 23 04:27:38 CET 2000


Y-ellow Scott 'n' y'all.
	Thanks for all the many suggestions.

It is already shifted right one bit so that it becomes a 7 bit value. This
should create something of a dead band as you suggested. However I still
get jitter. Curiously, last night when I put the air-conditioner on, as
soon as the breeze hit the pot it started to jitter. A gentle nudge cured
it but it would seem that's all it takes some times. Depending on the
position of the pot. 

One more shift would probably do it but then I don't get the resolution I
require.

Someone from the ATMEL list also suggested (and indeed showed me some code
for) averaging. The only problem is that his code was incapable of
rendering a value of zero. I think that perhaps if I incremented each word
by 1 it would overcome that problem.

However unless I remove some functions from the code, I don't have room to
put the averaging in. So I was really looking for a dirt simple hardware
solution if possible.

Accuracy isn't really important. It only has to read a pot as an actuator.
The user twirls the knob until they get the number they're after on the
display.

But I concede that software would be the best solution. Perhaps if I try an
average of 2 for a start. That way I don't have to go to multiple
precision. It might be just enough.

Thanks once again.

Be absolutely Icebox.

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