Using the Pmod ENC with Arduino Uno

/************************************************************************
*
* Test of the Pmod 
*
*************************************************************************
* Description: Pmod_ENC
* The direction of rotation of the encoder axis is displayed in the serial monitor.
* Pressing the push button memorizes the state of a counter in a variable
*
*
* Material
* 1. Arduino Uno
* 2. Pmod ENC 
*
************************************************************************/

// Affectation of pins
#define A 2 // output A of the encoder
#define B 3 // output B of the encoder
#define BTN 4 // button of the encoder

volatile boolean rotation;
volatile boolean sens;
int compteur = 0;
int validation = 0;

// Programme d'interruption
void Interruption ()
{
 if (digitalRead(A)==HIGH)
  {
  sens = digitalRead(B); // Clockwise
  }
 else
  {
  sens = !digitalRead(B); // anticlockwise
  }
 rotation = HIGH;
}
void setup()
{
 attachInterrupt (0,Interruption,FALLING); // interruption on falling edge of output A
 Serial.begin(9600); // initialization of the serial monitor
 pinMode(A,INPUT); // configuration of pin 2 in input
 pinMode(B,INPUT); // configuration of pin 3 in input
 pinMode(BTN,INPUT); // configuration of pin 4 in input
}

void loop()
{
 if (rotation==HIGH) // If detection of rotation
 {
  if (sens==HIGH) // if clockwise
   {
   compteur++; // increase counter 
   }
  else
   {
   compteur--; // decrease counter
   }
  rotation = LOW;
  Serial.print ("Compteur="); // write counter variable
  Serial.println (compteur);
 }
  if (digitalRead(BTN)==HIGH) // if the button have been activate
  {
  validation=compteur;
  delay(200); // debounce
  Serial.print ("Validation="); // write validation variable
  Serial.println (validation);
  }
}