HI Nick,

On Tue, Dec 6, 2011 at 12:49 PM, Greg Kogut <gkogut@yahoo.com> wrote:
If you're using Overo with the 40-pin header a safe bet for your two input lines is:

Pin 27 - gpio146
Pin 29 - gpio147

Per the first section of the wiki:

1)Export them to userspace
2)Set direction to "in"
3)Verify state with "echo"

These two pins are floating, so pull them low to get "0".   Pin 1 can be used as a ground.

Apply 1.8V to get "1". 

Make sure that you don't apply any more than 1.8v. Your tilt sensor probably outputs a higher voltage, and you'll need some type of voltage converter to convert the voltage from whatever your tilt sensor outputs down to 1.8v.

Dave Hylands
Shuswap, BC, Canada