Leon decided to make his own motion activated alarm using an Arduino and a PIR sensor. When the device is armed, when the PIR sensor detections motion it lights an LED. Ok. The interesting part here is he decided to add an ethernet shield to his Arduino and wrote some code to tell his Google ChromeCast to play a youtube video of an alarm.
So far I haven’t seen too many ChromeCast hacks that use an Arduino, hopefully this will inspire more.
Leon has put his Arduino sketch up on github for you right here.