alan smith <micro_eng2 <at> yahoo.com> writes:

>=20
> Using a 470K resistor in series, it pulls 7.3uA. Since I do have a few sp=
are
pins, I will take the idea of using
> one of the digital pins and drive it low to enable, then take the reading=
 with
the A/D. =20
>=20
> Thanks for the help!
>=20
>      =20

Take into account internal resistance of ADC, 470K pull-up/down might not b=
e
sufficient to pull voltage all the way to the rail.  Lower value resistor, =
like
10K or internal pull-up, sampled periodically, will give you more reliable
reading and low power.  Since you are detecting open/closed sensor, no need=
 for
ADC either - put micro into sleep instead of doing ADC and calculations to
detect threshold if you need to reduce power consumption even more.=20

Sergey Dryga
http://beaglerobotics.com


--=20
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