If you want to add a keypad to your Arduino project, the options are pretty limited. There’s that red and blue 4×4 membrane we’ve all seen in password-protected door lock projects,… ...

DIY Keypad Door Lock. ... The hack is still pretty hardware intensive, but Arduino fans will love this clever hack—especially if you're the type that locks yourself out of your room a lot.

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