#define POINT 100
#define TIRET 600

volatile boolean actif;
int led = 13;

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(2, INPUT_PULLUP);
  actif = false;
  attachInterrupt(digitalPinToInterrupt(2), serviceInt0, CHANGE);
}

void loop() {
  if (actif == true) {
    while (actif == true) {
      EcrireLettre('S');
      delay(100);
      EcrireLettre('O');
      delay(100);
      EcrireLettre('S');
      delay(300);
    }
  }
}

void serviceInt0(void) {
actif = digitalRead(2);
}

void EcrireLettre(unsigned char lettre) {
  if (lettre == 'S') {
    digitalWrite(led, HIGH);
    delay(POINT);
    digitalWrite(led, LOW);
    delay(POINT);
    digitalWrite(led, HIGH);
    delay(POINT);
    digitalWrite(led, LOW);
    delay(POINT);
    digitalWrite(led, HIGH);
    delay(POINT);
    digitalWrite(led, LOW);
  } else if (lettre == 'O') {
    digitalWrite(led, HIGH);
    delay(TIRET);
    digitalWrite(led, LOW);
    delay(TIRET);
    digitalWrite(led, HIGH);
    delay(TIRET);
    digitalWrite(led, LOW);
    delay(TIRET);
    digitalWrite(led, HIGH);
    delay(TIRET);
    digitalWrite(led, LOW);
  }
}