/* 4x4 Matrix Keypad connected to Arduino
   This code prints the key pressed on the keypad
   to the serial port */
#include <Keypad.h>

const byte numRows = 4; // number of rows on the keypad
const byte numCols = 4; // number of columns on the keypad

// keymap defines the key pressed according to
// the row and columns just as appears on the keypad
char keymap[numRows][numCols] = {
    {'1', '2', '3', 'A'},
    {'4', '5', '6', 'B'},
    {'7', '8', '9', 'C'},
    {'*', '0', '#', 'D'}
};

// Code that shows the keypad connections to the Arduino terminals
byte rowPins[numRows] = {9, 8, 7, 6}; // Rows 0 to 3
byte colPins[numCols] = {5, 4, 3, 2}; // Columns 0 to 3

// initializes an instance of the Keypad class
Keypad myKeypad = Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols);

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

// If key is pressed, this key is stored in 'keypressed' variable
// If key is not equal to 'NO_KEY', then this key is printed out
void loop() {
    char keypressed = myKeypad.getKey();
    if (keypressed != NO_KEY) {
        Serial.print(keypressed);
    }
}
// End Program