void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  pinMode(LED_BUILTIN, OUTPUT); // Set the built-in LED pin as an output
}

void loop() {
  if (Serial.available() > 0) { // Check if any data is available in the serial buffer
    char receivedChar = Serial.read(); // Read the character from the serial buffer
    if (receivedChar == '1') { // Check if the received character is '1'
      digitalWrite(LED_BUILTIN, HIGH); // Turn on the built-in LED
    } else if (receivedChar == '0') { // Optional: Turn off LED if '0' is received
      digitalWrite(LED_BUILTIN, LOW); // Turn off the built-in LED
    }
  }
  delay(10); // Add a small delay to avoid overwhelming the serial monitor
}