16-button membrane keyboard with interface component for microcontroller projects.

Convenient adhesive backing provides a simple way to mount the keypad in a variety of applications.

Application Ideas:

• security systems;
• menu selection;
• data entry for embedded systems.

How it Works

Matrix keypads use a combination of four rows and four columns to provide button states to the host 

device, typically a microcontroller. Underneath each key is a pushbutton, with one end connected to 

one row, and the other end connected to one column. These connections are shown here:

In order for the microcontroller to determine which button is pressed, it first needs to pull each of the four 

column s (pins 1-4 ) either low or high one at a time , and then poll the states of the four rows (pins 5-8). 

Depending on the states of the columns, the microcontroller can tell which button is pressed.