This calculator uses a full 16 button matrix keypad. The Arduino deciphers button pushes with the help of the Keypad library, at which time the appropriate character is displayed on the 2×8 LCD ...

This calculator solves a more practical problem ... Next up, a custom PCB to connect the keypad to an Arduino and a 20×4 LCD display was milled up, while a test case was designed and printed ...

Featuring an Arduino Nano microcontroller board and the keyboard from a small numeric keypad the LCD display the calculator is powered by a set of AA batteries through a DC-to-DC converter.

connect to the column C1-C3 pinouts of the keypad Next is a project example, where the Arduino is instructed to do something based on a correct key (secret number) being entered into the keypad, ...