UltraSonic Arduino How To - Parking your car with an Arduino

Using a Maxbotix Range Finder, Kevin Dahhar show you how to make a circuit that helps you back your car up into the garage, and put the Arduino into a super low power sleep when the circuit is not needed.

The Arduino only runs off of batteries and because it is kept in the super low power sleep mode the batteries last for months.

Only when the garage door is opened will the Arduino turn on due to the garage light activating a photocell and transistor circuit that signals an interrupt on the Arduino.

The code is well commented and very educational in itself.  You can look at it here

The video below is long but well worth the watch