For easy understanding, let’s arrange these 16 push buttons as the elements of a 4X4 Matrix i.e, in four rows and four columns. For a 4X4 keypad there are 4*4=16 push buttons. Let’s take 4X4 Matrix Keypad as a reference and understand the connections. Connecting the Push Buttons in a Matrix Keypad Format But, by using the Matrix type of configuration just 8-Pins are sufficient. We need 16-Pins of the microcontroller in order to read the status of these 16 switches/push buttons individually. For example, consider a 4X4 Matrix keypad, which contains 4*4=16 Keys. The advantage of these matrix keypads is that all the switches of the matrix can be read using lesser number of I/O pins of a processor/microcontroller. Here arrangement of keys doesn’t mean the layout of the keys or physical placement on the circuit board, but the keys are identified in terms of elements of a matrix like M11, M12, and so on… up to M44 for a 4X4 Matrix Keypad. The name itself infers that it has some keys arranged in rows and columns. The Computer keyboard is also a matrix keypad. The Matrix keypads are used in systems/control panels where Human Machine Interface (HMI) is required in order to change the operating parameters of a system/machine. In this article let’s discuss designing of matrix keypads and the programming part to get the information regarding the pressed key.
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