#define STEP 4
#define DIR 5

void setup() {
  pinMode(STEP, OUTPUT);
  pinMode(DIR, OUTPUT);
}

void loop() {
  digitalWrite(DIR, HIGH);
  for(int i = 0; i < 100; i++) {
    digitalWrite(STEP, HIGH);
    delay(10);
    digitalWrite(STEP, LOW);
    delay(10);
  }

  delay(1000);

  digitalWrite(DIR, LOW);
  for(int i = 0; i < 100; i++) {
    digitalWrite(STEP, HIGH);
    delay(10);
    digitalWrite(STEP, LOW);
    delay(10);
  }

  delay(1000);
}