#define EN 0  // PA4
#define PUL 1 // PA5
#define DIR 2 // PA6
#define REV 800 // steps/rev => 38mm
#define STEP_DIST 38 // mm
void rotate_CW(float distance) {
  Serial.print("Rotate  CW by "); Serial.println(distance); 
  int steps = (distance / STEP_DIST) * REV;
  digitalWrite(EN, HIGH);
  digitalWrite(DIR, LOW);
  for(int i = 0; i < steps; i++) {
    digitalWrite(PUL, LOW);
    delay(1);
    digitalWrite(PUL, HIGH);
  }
  digitalWrite(EN, LOW);
}

void rotate_CCW(float distance) {
  Serial.print("Rotate CCW by "); Serial.println(distance); 
  int steps = (distance / STEP_DIST) * REV;
  digitalWrite(EN, HIGH);
  digitalWrite(DIR, HIGH);
  for(int i = 0; i < steps; i++) {
    digitalWrite(PUL, LOW);
    delay(1);
    digitalWrite(PUL, HIGH);
  }
  digitalWrite(EN, LOW);
}

void rotate(float distance) {
  if (distance > 0) {
    rotate_CW(distance);
  } else {
    rotate_CCW(-distance);
  }
    Serial.println("Done");
}

void setup() {
  // put your setup code here, to run once:
  pinMode(EN, OUTPUT);
  pinMode(PUL, OUTPUT);
  pinMode(DIR, OUTPUT);

  // initialize stepper
//  digitalWrite(EN, HIGH);
  digitalWrite(PUL, HIGH);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (Serial.available()) {
//    String input = "";
//    input = Serial.readString();
//    Serial.print("Received:"); Serial.println(input);
    float input_distance = Serial.parseFloat();
    if (input_distance > 0 || input_distance < 0) {
      rotate(input_distance);
    }
    delay(1000);
  }
}