#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);
}
}