#include <Arduino.h>

#undef LED_BUILTIN
#define LED_BUILTIN PC13


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

void loop()
{
  digitalWrite(LED_BUILTIN, HIGH);
  Serial.println("Serial LED OFF");
  SerialUSB.println("SerialUSB LED OFF");

  delay(1000);

  digitalWrite(LED_BUILTIN, LOW);
  Serial.println("Serial LED ON");
  SerialUSB.println("SerialUSB LED ON");

  delay(1000);
}