Membrane Switch 20 Key 4x5 Matrix Array Keypad Keyboard Control Panel Microprocessor Keyboard Controller for Arduino 5x4 Product overview A low profile membrane keypad with 20 keys arranged in a 4 by 5 matrix. The unit includes an integrated microprocessor keyboard controller for easy connection to Arduino and other microcontrollers. Designed for reliable input in compact control panels and embedded projects. Key benefits Simple integration: The builtin microprocessor controller handles matrix scanning and common keyboard tasks, reducing programming effort and MCU I O usage. Space saving: Flat, low profile membrane design fits slim enclosures and saves space compared to mechanical key switches. Reduced wiring: The 4 by 5 matrix uses 9 I O lines total, minimizing wiring and connector complexity. Reliable input: Membrane construction provides consistent key activation and is easy to wipe clean, making it suitable for enclosed panels and light industrial use. Fully programmable: 20 individual keys can be mapped to functions or menu controls on Arduino and compatible microcontrollers. Main features and specifications Key layout: 20 keys arranged as 4 rows by 5 columns (4x5 matrix) Controller: Integrated microprocessor keyboard controller for simplified interfacing Compatibility: Designed for use with Arduino and other microcontrollers that support matrix key scanning Form factor: Thin membrane switch suitable for panel mounting or integration into portable enclosures Wiring: Matrix interface requires 9 digital lines (4 row lines plus 5 column lines) for direct connection Application flexibility: Can be used as a standalone keypad or as part of a larger control system Practical use scenarios DIY control panel: Use as the primary user interface for an Arduino based control panel for lighting, motor control, or home automation scene selection. Access and security keypad: Integrate into a door control or access system where compact size and cleanable surface are important. Instrumentation and vending: Add numeric or function input to measurement instruments, vending machines, or service terminals where a slim keypad is preferred. Installation and compatibility notes Connect the keypad matrix lines to digital I O pins on the host controller; confirm pin mapping in your project code. The integrated controller reduces the need to implement low level scanning and debouncing, but consult example code for results with Arduino. Ideal for projects that require a low profile interface with minimal mechanical complexity. Why choose this keypad This 20 key membrane switch delivers a compact, easy to integrate user interface for microcontroller projects. Its 4x5 matrix and onboard keyboard controller simplify wiring and software, making it a practical choice for hobbyists and system integrators who need a reliable, space efficient keypad solution.