//소스파일

void setup() {
  pinMode(3, OUTPUT);
  Serial.begin(9600);
  while (! Serial);
  Serial.println("Speed 0 to 255");
}

void loop() {
  if (Serial.available()){
    int speed = Serial.parseInt();
    if (speed >= 0 && speed <= 255){
      analogWrite(3, speed);
    }
  }
}