If, however, you find this too basic, there's a second version of the project with twice as many lines of code. In this version, you'll be using a keypad ... the LCD instead of just the Arduino ...

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 ...

Want your Arduino project to be able to play sounds ... your smartphone’s display to emulate a switch, slider, keypad, or LCD display without you actually having to wire anything up.