Lösung: Programmsteuerung mit seriellen Eingaben

/*
 * Created by ArduinoGetStarted.com
 *
 * This example code is in the public domain
 *
 * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-serial-monitor
 */

void setup() {
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT); // set the digital pin as output:
}

void loop() 
{
  if(Serial.available()) // if there is data comming

  {
    String command = Serial.readStringUntil('\n'); // read string until meet newline character

    if(command == "ON")
    {
      digitalWrite(LED_BUILTIN, HIGH); // turn on LED
      Serial.println("LED is turned ON"); // send action to Serial Monitor
    }
    else
      if(command == "OFF")
      {
        digitalWrite(LED_BUILTIN, LOW);  // turn off LED
        Serial.println("LED is turned OFF"); // send action to Serial Monitor
      }
  }
}