[Noisebridge-discuss] Long-lived, battery-powered AVRs

[Jonathan Lassoff]

On Mon, Jan 30, 2012 at 11:42 AM, Casey Callendrello <c1 at caseyc.net> wrote:
> What about using the gate latch to trigger a Polou switch?
> (http://www.sparkfun.com/products/8903). This was used by the famous
> Reverse Geocache to save battery life. It's a clever little switch that
> can be used to let a microcontroller turn itself off. When off, it draws
> (according to spec) .01ua.

That's more or less perfect for an application like this, though I
think it may not be a good contender, physically. Since this is to
detect a gate swinging open and shut, we were thinking of placing a
small coil-based sensor on the frame and a neodymium magnet on the
swinging gate.

Thank you everyone for some excellent suggestions. Sleeping the AVR
seems like the way to go, but waking it back up will be the trick.
Since I hope to use the small charge that will build as the magnet
passes over the coil, I was hoping to flip a small transistor. The
only problem I'm having is finding something that will trip with just
the slightest charge.
Would it be crazy to try and bias the gate of a small MOSFET so that
it's nearly triggered?

--j