#include <ESP32Servo.h>
#define TRIG_PIN  23  // ESP32 pin GIOP23 connected to Ultrasonic Sensor's TRIG pin
#define ECHO_PIN  22  // ESP32 pin GIOP22 connected to Ultrasonic Sensor's ECHO pin
#define SERVO_PIN 25  // ESP32 pin GIOP26 connected to Servo Motor's pin
#define LED_PIN 13  

Servo servo; // create servo object to control a servo

// variables will change:
float duration_us, distance_cm;

void setup() {
  Serial.begin (9600);       // initialize serial port
  pinMode(TRIG_PIN, OUTPUT); // set ESP32 pin to output mode
  pinMode(ECHO_PIN, INPUT);  // set ESP32 pin to input mode
  servo.attach(SERVO_PIN, 500, 2400);   // attaches the servo on pin 9 to the servo object
  pinMode(LED_PIN, OUTPUT);  // set arduino pin to output mode
}

void loop() {
  // generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin
  duration_us = pulseIn(ECHO_PIN, HIGH);
  // calculate the distance
  distance_cm = 0.017 * duration_us;

  if (distance_cm > 0 && distance_cm < 150 ) {
    servo.write(360); // rotate servo motor to 90 degree
    digitalWrite(LED_PIN, HIGH);
      Serial.print("distance: ");
      Serial.print(distance_cm);
      Serial.println(" cm"); }
 
  else {

    if (distance_cm >= 150 && distance_cm > 300){
    servo.write(-360);  // rotate servo motor to 0 degree
    digitalWrite(LED_PIN, LOW);
      Serial.print("distance: ");
      Serial.print(distance_cm);
      Serial.println(" cm");}

    else{
      delay(1000);
      servo.write(0);
      digitalWrite(LED_PIN, LOW);
      Serial.print("distance: ");
      Serial.print(distance_cm);
      Serial.println(" cm");
    }
  }

  delay(500);
}