const int led = 7;


void setup() {
  Serial.begin(9600);
  pinMode(led, OUTPUT);
  Serial.print(".");
}

void loop() {
  if(Serial.available()>0){
    char data = Serial.read();
    switch(data){
      case '0':
        digitalWrite(led, LOW);
        break;
      case '1':
        digitalWrite(led, HIGH);
        break;
      default:
        break;
    }
  }
}