#include <Keypad.h>

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3','A' },
  { '4', '5', '6','B' },
  { '7', '8', '9','C' },
  { '*', '0', '#','D' }

};
 uint8_t colPins[COLS] = {5,4,3,2};
 uint8_t rowPins[ROWS] = {9,8,7,6};

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

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

void loop() {
  char key = keypad.getKey();

  if(key !=NO_KEY) {
    Serial.println(key);
   
  }
}