Test for something connected to ADC Pin

Started by Leddy July 12, 2004
Is there a way to know if an ADC Pin is "null" or if something is connected
to it sending data?
I've used GetADC(13) with nothing connected to it and still read a result of
~300-350ish
Those could be values sent to it from the analog input, so I'm at a loss :(

Any suggestions or is what I'm asking not possible?

Leddy



It is reading those values bacause the pin is
floating... nothing to sink or supply current.

Are you asking if there is a way to test if something
is attached ?? On a recently related topic, I am
thinking that setting your pin to "Pull-up". If it
reads 1023, then either nothing is attached or 5 volts
is applied. If you set your pin to "High Impedance"
and it drops down to the 300-500 range, then nothing
was attached.

If, per chance, your pin is set to "pull-up" and
something is attached, the attached circuit should
sink the current enough to drop your voltage below
1023. Provided that you aren't measuring from a very
high resistance.

You may also notice that a floating pin will have
varying results...

Hope that answers your question,
Thad

--- Leddy <> wrote:
> Is there a way to know if an ADC Pin is "null" or if
> something is connected to it sending data?
> I've used GetADC(13) with nothing connected to it
> and still read a result of ~300-350ish
> Those could be values sent to it from the analog
> input, so I'm at a loss :(
>
> Any suggestions or is what I'm asking not possible?
>
> Leddy
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