On Mon, 13 Oct 1997 16:02:14 -0300 Ricardo Seixas
<rseixas@CICLONE.COM.BR> writes:
>Hi PICers
>
>        Does anyone know a quick and dirty way (no Op Amp) to measure
>a low
>battery condition ?

Use one of the Panasonic voltage detectors in the Digi-Key catalog with a
voltage divider on the supply pin.  The current drawn from this pin is
only 5uA or so so the voltage divider resistors can be large.


>        This pin must be shared, since all pins are already used :(

It depends on what sheme you're using for pin sharing.  They have 3 kinds
of outputs, I think CMOS, inverted CMOS, and open-drain.  You want the
open-drain one so the output current doesn't flow through the voltage
divider and upset the comparison.  If you cut the power to the open-drain
one (pull Vdd pin low through a diode), the output should stay at
high-impedance.