Keypad pin 1 to Arduino digital 3 //C2; Keypad pin 2 to Arduino digital 5 //R1; ... Although the code is an entry-level one, ... you have to fiddle the “rummy” keypad using your analog multimeter. It ...

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,… ...

The system auto-locks after 5 seconds, and just in case, [Andrea] has hard-coded in a few safety codes into the firmware to allow him to forcefully open the door — you know, if it malfunctions ...