arduino_led.ino

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
}
void loop() {
  if (Serial.available() > 0) {       // if there is data coming from the serial port
    int data = (int)Serial.read();  // get that data and print it
    Serial.println(data);
    if (data == 1) {                // do what you want with this data
        digitalWrite(13, HIGH);
    } 
    else if(data == 2){
        digitalWrite(13, HIGH);
        delay(1000);
        digitalWrite(13, LOW);
    }
    else if(data == 3){
        while(1){
          digitalWrite(13, HIGH);
          delay(1000);
          digitalWrite(13, LOW);
          delay(1000);
        }
    }
    else{
        digitalWrite(13, LOW);
    }
  }
}