use a repeater ( transistors if the mimimum level is allowing and the
thermal variation don't bother you,
or better an operational amplifier) to obtain a smaller output impedance,
then use Scott's method of measuring voltages using
digital pins. But I say also: change the pic to a 16F628 or
16F873/874/876/ or 16F74.

nothing but the best,
Vasile

On Thu, 18 Oct 2001, Roman Black wrote:

> Hi, I have a sensor that outputs about 10
> voltage levels between 0v and 5v dc. Close
> to evenly spaced but all different.
> Because of impedances, the smallest resistor
> I can attach to the sensor wire is about 100k.
>
> I have only 5 PIC input/output pins available,
> and no analog inputs unfortunately. The other
> problem is minimum parts cost and board space,
> maybe 1cm x 2cm. PIC is a 16C505. I can spare
> a transistor but would prefer to do it with
> discretes if possible. :o)
>
> My best attempt yet was to use a few high
> value resistors, as simple voltage dividers
> with the 100k input resistor, switched by
> 4 of the PIC pins and another pin to test.
> It's messy but maybe workable.
>
> Any other suggestions??
> -Roman
>
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