This project allows you to link up 8 push buttons, and have the Arduino read the buttons using only four wires.

The main thing is to download and extract the ShiftIn library from, and extract the ShiftIn directory into your Arduino/libraries directory.


Once you have done this, the code will compile and you can upload.


Open the Serial Monitor and when you press a button, the byte value will be printed to the console.


Any input that is not connected to a pushbutton needs to be pulled down to ground.