Numeric keypads like Keypad 4 X 3 Matrix Array Keyboard 12 Key Membrane Switches can provide a simple end-user alternative for various interfaces for your projects. Or if you need a lot of buttons, they can save you a lot of time with regards to construction.

Specifications:

We’ll use the small black keypad, an Arduino Uno-compatible, and an LCD with an I2C interface for display purposes. If you don’t have an LCD you could always send the text to the serial monitor instead.

If your keypad is different to ours, take note of the lines in the sketch from:

// keypad type definition

As you need to change the numbers in the arrays rowPins[ROWS] and colPins[COLS]. You enter the digital pin numbers connected to the rows and columns of the keypad respectively.

Furthermore, the array keys store the values displayed in the LCD when a particular button is pressed.

We’ll run through connecting them, using the Arduino library, and then finish with a useful example sketch.

Connecting 4x3 Keypad with Arduino:

To download Keypad Library for Arduino Click Here:

Arduino Code For Keypad 4 X 3 Matrix Array 12 Key Black to Print the key pressed on The Serial Monitor:

#include 

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns

char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3}; //connect to the column pinouts of the keypad

//Create an object of keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

void setup(){
  Serial.begin(9600);
}
  
void loop(){
  char key = keypad.getKey();// Read the key
  
  // Print if key pressed
  if (key){
    Serial.print("Key Pressed : ");
    Serial.println(key);
  }
}