const int pin = 8;
String option;
void setup(){
  Serial.begin(9600);
  pinMode(pin, OUTPUT);
}
void loop(){
  if (Serial.available()>0){
  option = Serial.readStringUntil('\n');
    if (option == "OFF"){digitalWrite(pin, LOW);}
    if (option == "ON"){digitalWrite(pin, HIGH);}
    delay(200);
  }
}