#include <Keypad.h>
#include <Wire.h> 

const byte numRows= 4;
const byte numCols= 4;

char keymap[numRows][numCols]= 
{
{'1', '2', '3', 'A'}, 
{'4', '5', '6', 'B'}, 
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};

byte rowPins[numRows] = {9,8,7,6}; 
byte colPins[numCols]= {5,4,3,2}; 

Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols);

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

void loop()
{
  char keypressed = myKeypad.getKey();
  if (keypressed != NO_KEY)
  {
  Serial.print(keypressed);
   }
}