#include <Stepper.h>

const int TRIGGER_PIN = 2;  
const int ECHO_PIN = 3;     
const int GREEN_LED_PIN = 5; 
const int DIR_PIN = 17;       
const int STEP_PIN = 18;      
const int STEPS_PER_REVOLUTION = 200; 
const int DISTANCE = 200;  

Stepper stepper(STEPS_PER_REVOLUTION, DIR_PIN, STEP_PIN);

void setup() {
  Serial.begin(9600);
  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);
  pinMode(STEP_PIN, OUTPUT);
}

void loop() {
  long duration, distance;
  

  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);
  
  
  duration = pulseIn(ECHO_PIN, HIGH);
  
  // Calculate distance
  distance = duration * 0.034 / 2; 
  
  Serial.print("Distance: ");
  Serial.println(distance);
  
 
  if (distance <= DISTANCE) {
  
    rotateStepper();
  
    digitalWrite(GREEN_LED_PIN, HIGH);
    delay(1000); 
    digitalWrite(GREEN_LED_PIN, LOW);
  }
}

void rotateStepper() {
  digitalWrite(DIR_PIN, HIGH); 
  for (int i = 0; i < STEPS_PER_REVOLUTION; i++) {
    digitalWrite(STEP_PIN, HIGH);
    delayMicroseconds(2000);
    digitalWrite(STEP_PIN, LOW);
    delayMicroseconds(2000);
  }
}