#define signal 3

  long debutPeriode;
  long timestamp;
  long check;

  long oldtime = 0;
  long time = 0;
  int count = 0;
  long Efreq = 200;
  int nb_palier = 10;
  int diametre_roue = 250;
  
  float speed;
  float frequency;
  String datamessage;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  attachInterrupt(digitalPinToInterrupt(signal),timeSinceFallingEdge, FALLING);

}

void loop() {

  timestamp = millis();
  if (timestamp - debutPeriode >= Efreq){


    frequency = (count*(1000/Efreq));
    speed = diametre_roue/2 * 3.14 * frequency / 10000;
	
    datamessage = String(count) + " " + String(frequency/nb_palier,4) + " " + "rpm" + " " + String(speed,4)+ " m/s" + " " + String(speed * 3.6 ,4)+ " km/h";

    count = 0;
    debutPeriode = millis();
    Serial.println(datamessage);
  }
  
  
  
  

}

void timeSinceFallingEdge() {
  check = micros();
  if (check - oldtime > 200){
    count += 1;
    oldtime = check;
  }
 
}