In the design of electronics project, it is very common to use a keypad matrix as a means for user to interface to the product. In order to minimize the number of pins used in the microcontroller, the keys should be arranged in as square a matrix as possible. One example is the use of 4 X 4 matrix arrangement in a 16 keys keypad. This arrangement require only 8 pins. If it is arrange in a 2 X 8 matrix, 10 pins will be needed instead of 8.
