Hello friends! In this tutorial, we will interface a matrix keypad with Arduino Uno and show each pressed key on a 20x4 LCD in Proteus. We will begin with the keypad's internal connections, then build the circuit and write a sketch that keeps the displayed text within a defined area. A keypad is useful when a project needs several related buttons, such as digits for a calculator or commands for a menu. A matrix arrangement reduces the number of controller connections compared with giving every button its own dedicated input. Our example uses twelve keys arranged in four rows and three columns. We will preserve the original circuit's pin assignments, explain how the Keypad library scans them, and check common mistakes such as reversed connector order, repeated characters and LCD overflow. F ...