#include <Keypad.h>

const byte COLS = 5;
const byte ROWS = 5;

char hexaKeys[ROWS][COLS] = 
{
  {'O','N','M','L','K'},
  {'J','I','H','G','F'},
  {'E','D','C','B','A'},
  {'9','8','7','6','5'},
  {'4','3','2','1','0'},
};

byte colPins[COLS] = {7, 8, 9, 10, 11};
byte rowPins[ROWS] = {2, 3, 4, 5, 6};

Keypad pad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);

void setup() 
{
  Serial.begin(9600);              
  Serial.println("Connected");
  pad.setHoldTime(100);              
  pad.setDebounceTime(50);
}

void loop() 
{
  char key = pad.getKey();
  //  pad.getState();
  if (key) 
  {
    Serial.println(key);  
  }
}