#define LED_J 2
#define LED_R 4

void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.println("Bonjour le monde !");

  pinMode(LED_J, OUTPUT);
  pinMode(LED_R, OUTPUT);
}

void loop() {
  digitalWrite(LED_J, HIGH);
  digitalWrite(LED_R, LOW);
  delay(500);
  digitalWrite(LED_J, LOW);
  digitalWrite(LED_R, HIGH);
  delay(500);
}