4X1 Matrix Keypad / 4 Buttons Matrix Keypad

This keyboard uses 4 keypads with one end connected to the row and the other end to the column. Since we have one keypad in each column, we simply have each keypad connected to one output pin. Keypads simply connect one pin to another, i.e. in our case, they connect the row and column in which they are located, as you can see in the image below.