Push Button Matrix

Several pushbuttons wired as a matrix, so the number of connections is far lower than the number of keys - a 4x4 grid of sixteen keys reads on eight pins rather than sixteen. This is how every keypad and computer keyboard works internally. Useful for adding numeric or menu input to a project without consuming most of a microcontroller's pins. Many keys read on far fewer pins than buttons; Works with the standard Arduino Keypad library; Suits numeric entry and menu navigation; Saves microcontroller I/O for other functions