#include <ESP32Servo.h>
const byte led = 15;
const byte servoPin = 21;
const byte trig = 13;
const byte echo = 12;
bool flag = true;

Servo servo;

void setup() {
  Serial.begin(9600);
  servo.attach(servoPin);
  pinMode(led, OUTPUT);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);

  servo.write(0);
  digitalWrite(led, LOW);
  digitalWrite(trig, LOW);
}

void loop() {
  long int dist = getDist();

  if (dist <= 10) {
    if (flag) {
      servo.write(180);
      digitalWrite(led, HIGH);
      delay(1000);
      flag = false;
    } else {
      servo.write(0);
      digitalWrite(led, LOW);
    }
  } else {
    servo.write(0);
    digitalWrite(led, LOW);
    flag = true;
  }

  delay(100);
}

int getDist() {
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  long int dur = pulseIn(echo, HIGH);
  long int dist = dur * 0.017;
  return dist;
}