I want to include a motion sensor in a GPS recorder circuit. PIR is out, since there won't be any light where it's mounted.
The purpose is simple: an on/off switch - on when the ship is moving, off when not. On a smartphone GPS app, I can opt to either use or not use the capabilities of the sensor.
Has anyone seen or built anything like I need? Online searches show only PIR setups; not going to work.