#define STEP_PIN 2
#define DIR_PIN  3
#define EN_PIN   4

#define CW_BUTTON  5
#define CCW_BUTTON 6

#define CW_LED  7
#define CCW_LED 8

#define SPEED_POT A0

// Stepper motor characteristics
#define STEPS_PER_REV 200

unsigned long lastStepTime = 0;
unsigned long lastPrintTime = 0;

int adcValue = 0;
int stepDelayUs = 2000;

bool clockwise = true;

void setup()
{
  Serial.begin(115200);

  // A4988
  pinMode(STEP_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);
  pinMode(EN_PIN, OUTPUT);

  // Buttons
  pinMode(CW_BUTTON, INPUT_PULLUP);
  pinMode(CCW_BUTTON, INPUT_PULLUP);

  // LEDs
  pinMode(CW_LED, OUTPUT);
  pinMode(CCW_LED, OUTPUT);

  // Enable A4988
  digitalWrite(EN_PIN, LOW);

  // Initial direction
  digitalWrite(DIR_PIN, HIGH);

  // Initial LED
  digitalWrite(CW_LED, HIGH);
  digitalWrite(CCW_LED, LOW);

  Serial.println("=================================");
  Serial.println("STM32 NUCLEO C031C6");
  Serial.println("STEPPER MOTOR CONTROL");
  Serial.println("=================================");
  Serial.println("Red Button  = CLOCKWISE");
  Serial.println("Black Button = COUNTER-CLOCKWISE");
  Serial.println("Potentiometer = SPEED");
  Serial.println();
}

void loop()
{
  // ------------------------------------------------
  // 1. READ POTENTIOMETER
  // ------------------------------------------------

  adcValue = analogRead(SPEED_POT);

  // Convert ADC value to step delay
  // Lower delay = higher speed
  stepDelayUs = map(adcValue, 0, 4095, 2000, 200);

  // ------------------------------------------------
  // 2. CLOCKWISE BUTTON
  // ------------------------------------------------

  if (digitalRead(CW_BUTTON) == LOW)
  {
    clockwise = true;

    digitalWrite(DIR_PIN, HIGH);

    digitalWrite(CW_LED, HIGH);
    digitalWrite(CCW_LED, LOW);

    delay(50);  // debounce
  }

  // ------------------------------------------------
  // 3. COUNTER-CLOCKWISE BUTTON
  // ------------------------------------------------

  if (digitalRead(CCW_BUTTON) == LOW)
  {
    clockwise = false;

    digitalWrite(DIR_PIN, LOW);

    digitalWrite(CW_LED, LOW);
    digitalWrite(CCW_LED, HIGH);

    delay(50);  // debounce
  }

  // ------------------------------------------------
  // 4. GENERATE STEP PULSES
  // ------------------------------------------------

  unsigned long currentTime = micros();

  if (currentTime - lastStepTime >= stepDelayUs)
  {
    lastStepTime = currentTime;

    digitalWrite(STEP_PIN, HIGH);

    delayMicroseconds(5);

    digitalWrite(STEP_PIN, LOW);
  }

  // ------------------------------------------------
  // 5. SERIAL MONITOR
  // ------------------------------------------------

  if (millis() - lastPrintTime >= 500)
  {
    lastPrintTime = millis();

    float stepsPerSecond = 1000000.0 / stepDelayUs;

    float rpm =
      (stepsPerSecond * 60.0) / STEPS_PER_REV;

    Serial.print("ADC = ");
    Serial.print(adcValue);

    Serial.print(" | Direction = ");

    if (clockwise)
      Serial.print("CLOCKWISE");
    else
      Serial.print("COUNTER-CLOCKWISE");

    Serial.print(" | Steps/sec = ");
    Serial.print(stepsPerSecond, 1);

    Serial.print(" | RPM = ");
    Serial.println(rpm, 1);
  }
}