Controle posicao de Step com Potencimetro

  /* FILE:    Posição Step
     DATE:    17/11/15
     VERSION: 0.1
     AUTHOR:  Rui
  */

  #define DIR_PIN 8 //Connect to drive modules 'direction' input.
  #define STEP_PIN 9 //Connect to drive modules 'step' or 'CLK' input.

  /* Set the analogue pin the potentiometer will be connected to. */
  #define POT_PIN A0
  int Pos = 0;  // inicial position off stepper
  int Speed, Val;
  unsigned int Angulo;
  byte Vel = 10;
  byte Sample = 20;
  //---------------------------------
  void setup()
  {
    Serial.begin(9600);
    pinMode(DIR_PIN, OUTPUT);
    pinMode(STEP_PIN, OUTPUT);
  }
//--------------------------------
  void loop()
  {
    for (unsigned int j = 0; j<Sample ; j++)
    {
      Val = Val = analogRead(POT_PIN);
      delay(1);
    }
    Val + Val /Sample;
    Angulo = map(Val,0,1023,1,100);
    Pos = Angulo-Pos;
    if (Pos>0)
     {
       digitalWrite(DIR_PIN,HIGH);
       for (unsigned i = 0 ; i<abs(Pos) ; i++)
       {
         digitalWrite(STEP_PIN,HIGH);
         delay(Vel);
         digitalWrite(STEP_PIN,LOW);
         delay(Vel);
       }
     }
     else
     {
       digitalWrite(DIR_PIN,LOW);
       for (unsigned i = 0 ; i<abs(Pos) ; i++)
       {
         digitalWrite(STEP_PIN,HIGH);
         delay(Vel);
         digitalWrite(STEP_PIN,LOW);
         delay(Vel);
       }
     }
     Pos = Angulo;
  }