No I haven't ... nice idea.  Not sure it would work easily in my app thou=
gh. =20
I was going to use 2 pics in here ... both running with the internal=20
oscillator, and every single pin maxed out, except the one a/d input. :-(

To do this, I'd need one of the PICs to run in RC mode, AND an external c=
lock=20
(or external xtal) to compare the frequencies (or perhaps have the other =
PIC=20
drive it, but that requires even more I/O line).

I'd also need to add another resistor or 2 to adjust or shift the sensor=20
resistance range to an RC-osc-allowed resistance range.

So to properly pull this off, I'd need a third PIC, and I really don't wa=
nt to=20
do this, assuming I could even find the space to squeeze it in.  See what=
 a=20
painful life I live!? :-)

Cheers,
-Neil.



On Wednesday 30 July 2003 16:03, Mike Singer scribbled:
> Neil wrote:
> > The voltage-divider is made up of 2 resistors -- one is
> > the temp sensor (ground to center) and the other is a
> > fixed value (+5V to center). Depending on what range I
> > need (still undetermined), I'll pick a fixed resistor
> > to get maximum voltage-range into the PIC A/D input.
> > That will determine the actual current flow and thus the
> > amount of self-heating.
>
> Did'ya think about putting your resistive-output temp
> sensor in place of a resistor of the PIC's RC OSCILLATOR ?
>
> Cheappest PIC is about 1$.
>
> Mike.

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