If you want to add a keypad to your Arduino project ... s that red and blue 4×4 membrane we’ve all seen in password-protected door lock projects, and the phone layout version that does pretty ...

If a keypad has 12 keys, it is wired as 3 columns by 4 rows. A 16 key pad would have 4 columns by 4 rows. Some time ago, I bought a couple of 3×4 membrane keypads from ... Next is a project example, ...