byte inSer, str;
void setup() {
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  Serial.begin(9600);
  Serial.println("Kontrol LED via PC");
}

void loop() {
  inSer = Serial.read(); //membaca kode ASCII
  str = char (inSer); //mengubah data ASCII ke string
  switch(str){
    case('1')://LED 1 ON
      digitalWrite(2, HIGH);digitalWrite(3, LOW);digitalWrite(4, LOW);
      Serial.println(("LED 1 ON")); break;
    case('2')://LED 2 ON
      digitalWrite(2, LOW);digitalWrite(3, HIGH);digitalWrite(4, LOW);
      Serial.println(("LED 2 ON")); break;
    case('3')://LED 3 ON
      digitalWrite(2, LOW);digitalWrite(3, LOW);digitalWrite(4, HIGH);
      Serial.println(("LED 3 ON")); break;
  }
}