Did you know that you can use Arduino to turn on an LED when you press a button? Well, it is true, you can do this! Leaving the joke aside, let me show how you can achieve this. You will need the ...

The Arduino can just increment the counter up to the appropriate LED. The Arduino then controls the state of the LED using the active high enable line from the column multiplexer chip.

He builds a simple dead bug Arduino (which he calls an Audioino) using a handful of resistors, a pair of caps, an LED, a reset switch, and most importantly – an audio jack.