1  
 2  #define ledPin 13
 3  
 4  void setup() {
 5    pinMode(ledPin, OUTPUT);
 6    Serial.begin(9600);
 7  }
 8  
 9  void loop() {
10    while (Serial.available()) {
11  
12      String data = Serial.readStringUntil('\n');
13      data.trim(); // Remove whitespace/newlines
14      
15      // For Debugging
16      //Serial.print("Received: ");
17      //Serial.println(data);
18  
19      if (data == "ON" || data == "on"){
20        digitalWrite(ledPin, 1);
21      }
22      else if(data == "OFF" || data == "off"){
23        digitalWrite(ledPin, 0);
24      }
25      else {
26        digitalWrite(ledPin, 0);
27      }
28    }
29  }