// In this procedure, we will control a relay using
// commands from the Serial Monitor (1 = ON, 0 = OFF)

int relayPin = 8;   // Relay signal pin connected to D8
char command;       // Variable to store the Serial Monitor input

void setup() {
  Serial.begin(9600);        // Start Serial communication
  pinMode(relayPin, OUTPUT); // Set relay pin as output
  digitalWrite(relayPin, LOW); // Start with relay OFF

  Serial.println("=== Relay Control System ===");
  Serial.println("Type 1 to TURN ON the relay");
  Serial.println("Type 0 to TURN OFF the relay");
}

void loop() {
  // Check if data is available from Serial Monitor
  if (Serial.available() > 0) {
    command = Serial.read();  // Read one character from Serial input

    if (command == '1') {
      digitalWrite(relayPin, HIGH);    // Turn relay ON
      Serial.println("Relay is ON 🔛");
    }
    else if (command == '0') {
      digitalWrite(relayPin, LOW);     // Turn relay OFF
      Serial.println("Relay is OFF 🔴");
    }
    else {
      Serial.println("Invalid command! Type 1 or 0 only.");
    }
  }
}