Keypad Tutorial with Arduino

Let's explore the functionality of the 4x4 Keypad - a device with sixteen push buttons arranged in a 4x4 matrix, commonly used for inputting data or controlling menu options in embedded systems, such as Arduino projects.

BASICS

The Arduino 4x4 keypad is a device that allows for user input in a compact and easy-to-use format. The keypad consists of 16 buttons arranged in a 4x4 grid, with each button corresponding to a unique symbol or character. By connecting the keypad to an Arduino board, you can read the button presses and use them for a variety of applications.

The keypad typically connects to the Arduino's digital input pins, with each row and column of buttons connected to a specific pin. When a button is pressed, it completes a circuit between the corresponding row and column pins, allowing the Arduino to detect the button press.

Wiring Diagram

row Pin 1 -> Arduino 9

row Pin 2 -> Arduino 8

row Pin 3 -> Arduino 7

row Pin 4 -> Arduino 6 column pin 1 -> Arduino 5 column pin 2 -> Arduino 4 column pin 3 -> Arduino 3 column pin 4 -> Arduino 2

CODE

#include <Keypad.h>

const byte ROWS = 4; // number of rows in the keypad

const byte COLS = 4; // number of columns in the keypad

// define the symbols on the buttons of the keypad

char keys[ROWS][COLS] = {

{'1', '2', '3', 'A'},

{'4', '5', '6', 'B'},

{'7', '8', '9', 'C'},

{'*', '0', '#', 'D'}

};

// define the row and column pins of the keypad

byte rowPins[ROWS] = {9, 8, 7, 6};

byte colPins[COLS] = {5, 4, 3, 2};

// initialize the keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {

Serial.begin(9600); // initialize serial communication

}

void loop() {

char key = keypad.getKey(); // read the pressed key

if (key != NO_KEY) { // if a key is pressed

Serial.print("You pressed: ");

Serial.println(key); // print the pressed key to the serial monitor

}

}