#4.10.1.1. 예제 

#include <Keypad.h>

char keys[4][4] = {

  {'1', '2', '3', 'A'},

  {'4', '5', '6', 'B'},

  {'7', '8', '9', 'C'},

  {'*', '0', '#', 'D'}

};

byte rowPins[4] = {2, 3, 4, 5};

byte colPins[4] = {6, 7, 8, 9};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, 4, 4);

void setup() {

  Serial.begin(9600);

}

void loop() {

  char key = keypad.getKey();

  if (key) {

    Serial.println(key);

  }

}