You can read the state of a button using Arduino and a few lines of code. The actual state is shown in the Serial Monitor window as 0 or 1, 0 meaning the ...

The remote control is used to turn the Pi on. The Arduino reads the IR code from a remote and simply powers up the Pi.

The Adafruit Gemma measures just 1 inch in size and is powered by an ATtiny85 and programmable with an Arduino IDE over USB, allowing you to create those wearable projects of the future.