Matrix keypad consists of a set of buttons similar to an alphanumeric keyboard provided with keys usually marked with letters or numbers and various extra keys. Embedded systems which require user interaction must be interfaced with devices that accept user input such as a keypad. The Spartan-3 Primer board has 4x4 Matrix Keypad, indicated as in Figure. Keypads
arranged by matrix format, each row and column section pulled by high, all row lines and column lines connected directly by the i/o pins.