const int ledPin = 13;  // Built-in LED on most Arduino boards

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  Serial.println("LED Control: Send 'ON' to turn LED on, 'OFF' to turn it off");
}

void loop() {
  if (Serial.available() > 0) {
    String command = Serial.readStringUntil('\n');
    command.trim();  // Remove any whitespace
    
    if (command.equalsIgnoreCase("ON")) {
      digitalWrite(ledPin, HIGH);
      Serial.println("LED turned ON");
    } 
    else if (command.equalsIgnoreCase("OFF")) {
      digitalWrite(ledPin, LOW);
      Serial.println("LED turned OFF");
    }
    else {
      Serial.println("Unknown command. Use 'ON' or 'OFF'");
    }
  }
}