int pinA = 2;   // Le port D2 est associé à l'interruption 0
int pinB = 4;
int t1 = 0;
volatile long encodeurPosition = 0;
unsigned long lastTime = 0;
float rpm = 0.0;

void setup ()
{
  pinMode(pinA, INPUT);
  pinMode(pinB, INPUT);
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(pinA), test, CHANGE);

}

void loop ()
{
unsigned long currentTime = millis();
    if (currentTime - lastTime >= 3000) {
      float revs = float(encodeurPosition)/20;
      rpm = abs(revs/3);
      rpm = (rpm*60);
      rpm = (rpm/2);
      encodeurPosition = 0;
      lastTime = currentTime;
      Serial.println(rpm);
    }
    //Serial.print("RPM: ");
    
}

void test () 
{
if (digitalRead(pinA) == digitalRead(pinB)) {
    encodeurPosition++;
    delay(30);
  } else {
    encodeurPosition--;
    delay(30);
  }

  //Serial.println(encodeurPosition);
}