― Constructing a Matrix Keypad ∙ Scanning a Matrix Keypad There are many methods depending on how you connect your keypad with your controller, but the basic logic is same. We make the coloums as i/p and we drive the rows making them o/p, this whole procedure of reading the keyboard is called scanning. ∙ In order to detect which key is pressed from the matrix, we make row lines low one by one and read the coloums. Lets say we first make Row1 low, then read the columns. If [...].