NEMA17 Stepper Motor

// Canonical NEMA17 stepper motor example using an A4988-style driver.
// Wiring:
// Arduino D2 -> STEP
// Arduino D3 -> DIR
// Arduino D4 -> EN (active LOW)
// Arduino 5V -> VDD
// Arduino GND -> GND
// Potentiometer CW -> 5V, CCW -> GND, WIPER -> A0
// Motor coils -> driver outputs 1A/1B and 2A/2B

const int STEP_PIN = 2;
const int DIR_PIN  = 3;
const int EN_PIN   = 4;
const int POT_PIN  = A0;

void stepMotor(long steps, bool direction, unsigned int stepDelayMicros) {
  digitalWrite(DIR_PIN, direction ? HIGH : LOW);

  for (long i = 0; i < steps; i++) {
    digitalWrite(STEP_PIN, HIGH);
    delayMicroseconds(stepDelayMicros);
    digitalWrite(STEP_PIN, LOW);
    delayMicroseconds(stepDelayMicros);
  }
}

void setup() {
  pinMode(STEP_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);
  pinMode(EN_PIN, OUTPUT);

  digitalWrite(STEP_PIN, LOW);
  digitalWrite(DIR_PIN, LOW);
  digitalWrite(EN_PIN, HIGH); // disable driver at start

  Serial.begin(9600);
  while (!Serial) { }

  Serial.println("NEMA17 stepper motor demo with A4988 driver");
  Serial.println("Turn the potentiometer to change speed.");
  Serial.println("The motor alternates direction after each full rotation.");
}

void loop() {
  int pot = analogRead(POT_PIN);
  unsigned int stepDelayMicros = map(pot, 0, 1023, 2000, 300);
  const int stepsPerRevolution = 200; // typical 1.8 degree NEMA17 motor

  digitalWrite(EN_PIN, LOW); // enable driver

  Serial.print("Speed control pot=");
  Serial.print(pot);
  Serial.print("  step delay(us)=");
  Serial.println(stepDelayMicros);

  Serial.println("Rotating clockwise...");
  stepMotor(stepsPerRevolution, true, stepDelayMicros);
  delay(500);

  Serial.println("Rotating counterclockwise...");
  stepMotor(stepsPerRevolution, false, stepDelayMicros);
  delay(500);
}