#include <Keypad.h>

const int ROWS = 4; // Number of rows in the keypad
const int COLS = 4; // Number of columns in the keypad

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

byte rowPins[ROWS] = {6, 7, 8, 9}; // Connect to R1, R2, R3, R4 on the keypad
byte colPins[COLS] = {2, 3, 4, 5}; // Connect to C1, C2, C3, C4 on the keypad

const int relayPin = 10; // Connect to the Signal (IN) pin of the relay module

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

void setup() {
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW); // Initialize the relay as OFF
  Serial.begin(9600);
}

void loop() {
  char key = keypad.getKey();
  
  if (key != NO_KEY) {
    Serial.println(key); // Print the pressed key to the Serial Monitor
    
    // Check if the pressed key is a specific key (you can customize this part)
    if (key == 'A') {
      digitalWrite(relayPin, HIGH); // Turn ON the relay
    } else if (key == 'B') {
      digitalWrite(relayPin, LOW); // Turn OFF the relay
    }
  }
}