    /* Utilisation du capteur Ultrason HC-SR04 */

    // définition des broches utilisées
    int LedRed = 11;
    int LedGreen = 10;
    int LedBlue = 9;
    int trig = 8;
    int echo = 7;
    long lecture_echo;
    long cm;

    void setup()
    {
      pinMode(LedRed, OUTPUT);
      pinMode(LedGreen, OUTPUT);
      pinMode(LedBlue, OUTPUT);
      pinMode(trig, OUTPUT);
      digitalWrite(trig, LOW);
      pinMode(echo, INPUT);
      Serial.begin(9600);
    }

    void loop()
    {
      digitalWrite(trig, HIGH);
      delayMicroseconds(10);
      digitalWrite(trig, LOW);
      lecture_echo = pulseIn(echo, HIGH);
      cm = lecture_echo / 58;
      Serial.print("Distance : ");
      Serial.print(cm);
      Serial.println(" cm.");
      if(cm > 50){
              analogWrite(LedRed,0);
              analogWrite(LedGreen, 255);
              analogWrite(LedBlue, 0);
              //digitalWrite(LedGreen, HIGH);
              //digitalWrite(LedBlue, LOW);
              //digitalWrite(LedRed, LOW);
         }

         else if(cm >= 20 && cm <= 50){
              analogWrite(LedRed, 255);
              analogWrite(LedGreen, 128);
              analogWrite(LedBlue, 0);
              //digitalWrite(LedBlue, HIGH);
              //digitalWrite(LedRed, LOW);
         }

         else {
              analogWrite(LedRed, 255);
              analogWrite(LedGreen, 0);
              analogWrite(LedBlue, 0);
              //digitalWrite(LedGreen, LOW);
              //digitalWrite(LedBlue, LOW);
              //digitalWrite(LedRed, HIGH);
         }
      delay(100);
    }