Keypad Button 4x4 Numeric Matrix Array Rubber-Domes

Rubber-domes beneath each button provide satisfying key travel with each button press. Each key is emblazoned with a legible white character molded into its surface.
The single-row 0.1-inch-pitch solder pads are breadboard friendly. Only eight of the ten solder pads carry signals - the solder pads on the ends of the row are purely for mechanical attachment.

Specifications:

• Working Voltage: 3 - 5V DC
• 8-PIN MRconnect hole
• Mounting Hole Diameter : 2mm
• Dimensions: Keypad: 68mm x 65mm
• Operating temperature: 0°C to 50°C

Connect Keypad to Arduino

You can download the Keypad library here: Keypad Library. When you download, change the name to folder to something other than Keypad. If the folder and the file you are importing have the same name, it won't work.

/*4x4 Matrix Keypad connected to Arduino
This code prints the key pressed on the keypad to the serial port*/

#include <Keypad.h>

const byte numRows= 4; //number of rows on the keypad
const byte numCols= 4; //number of columns on the keypad

//keymap defines the key pressed according to the row and columns just as appears on the keypad
char keymap[numRows][numCols]=
{
   {'1', '2', '3', 'A'},
   {'4', '5', '6', 'B'},
   {'7', '8', '9', 'C'},
   {'*', '0', '#', 'D'}
};

//Code that shows the the keypad connections to the arduino terminals
byte rowPins[numRows] = {9,8,7,6}; //Rows 0 to 3
byte colPins[numCols]= {5,4,3,2}; //Columns 0 to 3

//initializes an instance of the Keypad class
Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols);

void setup()
{
   Serial.begin(9600);
}

//If key is pressed, this key is stored in 'keypressed' variable
//If key is not equal to 'NO_KEY', then this key is printed out
//if count=17, then count is reset back to 0 (this means no key is pressed during the whole keypad scan process
void loop()
{
   char keypressed = myKeypad.getKey();
   if (keypressed != NO_KEY)
   {
      Serial.print(keypressed);
   }
}

With this code, once we press a key on the keypad, it should show up on the serial monitor of the Arduino IDE once the code is compiled and uploaded to the Arduino board.