#define clkPin    2
#define dtPin     3
#define swPin     4   // Bouton Poussoir (Reset)

#define outPWM    8
#define StepPWM   15
#define numPWM    255  // Niveaux PWM


int nReset=1; 

void setup() 
{
  //Init 
  Serial.begin(19200);
  pinMode(clkPin,INPUT);
  pinMode(dtPin,INPUT);
  pinMode(swPin,INPUT_PULLUP);
  
  pinMode(outPWM,OUTPUT);
  analogWrite(outPWM,0);
}

void loop() 
{
  // Lecture de l'encodeur
  nReset=digitalRead(swPin); 
  int R=encodUpDown(clkPin,  dtPin,  numPWM, StepPWM, 200, nReset); 

  // Affichage (Test)
  Serial.print(R); Serial.print("\t");
  Serial.println(R); 
  
  // Mise à jour intensité 
  analogWrite(outPWM,R);
}

int encodUpDown(int clkpin, int dtpin, int rotmax,int stpwm, int delay_ms, int nrst) 
{ 
  static int rotVal  = 0;
  static bool clkState  = LOW, clkLast  = HIGH;

  clkState = digitalRead(clkpin);
  if ((clkLast == LOW) && (clkState == HIGH)) 
  {
    if (digitalRead(dtpin) == HIGH) // Down 
    {
      rotVal-=stpwm;
      if ( rotVal < 0) rotVal = 0;
    }
    else  // Up
    {
      rotVal+=stpwm;
      if ( rotVal >= rotmax)rotVal = rotmax;
    }
    delay(delay_ms);
  }
  clkLast = clkState;

  // Init 
  if (nrst==0)
  {
    rotVal   = 0; 
    clkState = LOW; 
    clkLast  = HIGH;
  }
  return rotVal; 
}