Teste

 #define Step 9          // Clk+
  #define Dir 8           // Cw+
  #define leitura  3      // botao
  unsigned int Qtde_Steps = 50;
  unsigned int velocity = 100;

  //--------------------------------------------
  void setup()
  {
    Serial.begin(9600);
    pinMode(leitura, INPUT_PULLUP);
    pinMode(Dir, OUTPUT);
    pinMode(Step, OUTPUT);
    digitalWrite(Dir, LOW);
    digitalWrite(Step, LOW);
    digitalWrite(Dir, HIGH);
  }
  //---------------------------------------------
  void loop()
  {
 //   if (leitura == LOW)
//    {
      for ( int i = 0; i < 50 ; i++)
      {
        digitalWrite(Step, HIGH);
        delayMicroseconds(100);
        digitalWrite(Step, LOW);
        delayMicroseconds(100);
      }
 //   }
  }