const int ledPin = 7;

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if(Serial.available() > 0) {
    char data = Serial.read();

    if(data == '1') {
      digitalWrite(ledPin, HIGH);
    }

    else if(data == '0') {
      digitalWrite(ledPin, LOW);
    }
  }

}