#define Step 21
#define Dir 4

const int SPR=200;
const int Delay=2000;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(Step, OUTPUT);
  digitalWrite(Step, LOW);
  pinMode(Dir, OUTPUT);
}

void loop() {
  digitalWrite(Dir, HIGH);
  for(short i=0; i<SPR; i++){
    digitalWrite(Step, HIGH);
    delayMicroseconds(Delay);
    digitalWrite(Step, LOW);
    delayMicroseconds(Delay);
  }
  
  digitalWrite(Dir, LOW);
  for(short i=0; i<SPR; i++){
    digitalWrite(Step, HIGH);
    delayMicroseconds(Delay);
    digitalWrite(Step, LOW);
    delayMicroseconds(Delay);
  }
  delay(2000);
}