int led = 6;

void setup (){
  pinMode(led, OUTPUT);
  Serial.begin(115200);
}

void loop(){
  led_Switch();
}
void led_Switch(){
if (Serial.available()){
    int state = Serial.parseInt();

    if (state == 1){
      digitalWrite(led, HIGH);
    }
    if (state == 0){
      digitalWrite(led, LOW);
    }
  }
}