4x4 Micro Switch Matrix Keypad

16-Key Matrix Input

The 4×4 Micro Switch Matrix Keypad provides 16 individual keys arranged into four rows and four columns.

A typical keypad layout contains numerical keys along with additional function keys, allowing it to be used as a compact user-input device for embedded systems.

Matrix Scanning Technology

Instead of requiring one GPIO pin for every key, the keypad connects its switches in a row-and-column matrix.

The four row lines and four column lines can be scanned by a microcontroller to determine which key has been pressed. This allows all 16 switches to be monitored using 8 GPIO connections.

Matrix scanning is commonly implemented through software or an appropriate keypad library.

Tactile Micro Switches

Each key uses a momentary switch that provides physical feedback when pressed. This makes the keypad suitable for applications where users need to enter commands or values repeatedly.

Arduino & ESP32 Compatible

The keypad can be connected to a wide range of development platforms, including:

• Arduino Uno
• Arduino Nano
• Arduino Mega
• ESP32
• ESP8266
• Raspberry Pi
• STM32
• Other compatible microcontrollers

The keypad itself is a passive switch matrix, so it does not require a dedicated controller IC.

Simple Wiring

The standard 4×4 matrix requires 8 signal connections:

• Row 1
• Row 2
• Row 3
• Row 4
• Column 1
• Column 2
• Column 3
• Column 4

The microcontroller scans these connections to identify the pressed key.

Suitable Applications

The 4×4 keypad can be used for:

• Digital door locks
• Password entry systems
• Security prototypes
• Calculators
• Menu navigation
• Vending-machine prototypes
• Robotics controllers
• Home automation
• Industrial control prototypes
• Data-entry systems
• Arduino projects
• ESP32 projects
• Educational electronics
• DIY control panels

Digital Lock Projects

One of the most common uses is creating a password-based access-control prototype. The user enters a PIN through the keypad, while a microcontroller compares the input against a programmed value and controls a suitable output device.

Compact User Interface

For embedded projects that need a physical control interface without a full-size keyboard, the 4×4 matrix keypad provides a simple and inexpensive solution.

Important: The keypad is a switch matrix and does not provide voltage regulation, processing, or data storage. A compatible microcontroller or control circuit is required to interpret key presses.