#include <Keypad.h>

// Define the rows and columns of the keypad
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

// Define the keymap
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

// Connect keypad ROW0, ROW1, ROW2, ROW3 to Arduino pins
byte rowPins[ROWS] = {9,8,7,6};

// Connect keypad COL0, COL1, COL2, COL3 to Arduino pins
byte colPins[COLS] = {5,4,3,2};

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

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

void loop() {
  char key = keypad.getKey();
  if (key) {
    Serial.println(key);
  }
}