void setup() { 
  Serial.begin(115200);
  Serial.println("coba serial");
  pinMode(13, OUTPUT);

  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
}

void loop() { 
  Serial.println("coba serial loop");
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
}