#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

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

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

int ledPins[4] = {10, 11, 12, 13};

void setup() {
  Serial.begin(9600);
  for (int i = 0; i < 4; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}
void loop() {
  char key = keypad.getKey();
  if (key) {
    Serial.println(key);
  }
}



int keyToBinaryValue(char key) {
 
  if (key >= '0' && key <= '9') {
    return key - '0';
  } else {
    return 0; 
  }
}

void displayBinary(int value) {
  for (int i = 0; i < 4; i++) {
    digitalWrite(ledPins[i], (value >> i) & 0x01);
  }
}