Little-Scale shares tips for using a button keypad with the Arduino platform –
The idea of the digital scanning of a keypad is very simple. The keypad in question has twelve buttons, set up in four rows of three (like a phone keypad, for example). Each button has two connection points â€“ one point goes to a row pin, and one point goes to a column pin. Therefore, seven pins are connected between the keypad and the Arduino â€“ four for the rows and three for the columns. When a button is pushed, it connects the two points â€“ a column pin and a row pin.
Read on for more detail – How to read a keypad with Arduino