Dan Michaels wrote:
>
> Roman Black wrote:
> >Hi Dan,
> >
> >        I have a battery voltage sensor using one PIC pin
> >that doesn't need the ADC feature, so it can be used on
> >any cheaper PIC that only has digital inputs. It does
> >require that the PIC is run from a regulator and the battery
> >voltage changes but the PIC Vdd does not. It uses about 30uA
> >so is useful for some circuits.
> >It uses two resistors and one small ceramic cap.
> >-Roman
> >
>
> Of course, mine is soooo much slicker, cause I do use an
> A/D channel <-- choice of control freaks everywhere.
>
> So when you gonna show your ckt, anyways, Roman? [use large
> Rs, pull down pin, switch pin to input, count seconds for pin
> to exceed Vin(threshold)].
>
> - danM

Actually Dan, your circuit is better than mine! I used a
resistor divider from battery to PIC pin to GND, with
the cap on the ground side. I pulled the pin high and
count cycles for it to get down to low level. Bottom
R is much less ohms of course.

Your idea just needs one R from battery + to the pin,
with the cap to gnd. Then pull the pin low and count for
it to get high again. With a 560k resistor and the pin
held high by software, your circuit would use much less
power too. Good way to measure a battery voltage with
just a digital pin (not ADC). Pretty cool!
-Roman

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