#define BAUD 9600
#define led 13

String receivedString;

void setup() {
  Serial.begin(BAUD);
  pinMode(led, OUTPUT);
}

void loop() {
  if (Serial.available() > 0){
	 receivedString = Serial.readStringUntil('\n');
   receivedString.trim();
   if (receivedString=="PIN13_1")
		digitalWrite(led, HIGH);
	 else if (receivedString.equals("PIN13_0")) 
		digitalWrite(led, LOW);
  }
}