#include <Keypad.h>

// Character to hold key input
char customKey;

// Constants for row and column sizes
const byte ROWS = 4;
const byte COLS = 4;
//***************
// Array to represent keys on keypad
char hexaKeys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
// ***************  key board harware Connections to Arduino mega

byte rowPins[ROWS] = {31, 33, 35, 37};
byte colPins[COLS] = {23,25,27,29};

// Create keypad object
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);

void setup() {
  // put your setup code here, to run once:
 Serial.begin(115200);  // to see in serial monitor dont use this  Serial.begin if pin 0,1 is used for high or low, in this project it is used
}

void loop() {
customKey = customKeypad.getKey();  // should be looped here else will not wait
   if (customKey) {
      Serial.println(customKey);
   }
}