#include <ESP32Servo.h>

Servo gate;

#define TRIG 5
#define ECHO 18
#define LED 2
#define SERVO_PIN 19

long duration;
float distance;

void setup() {

  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(LED, OUTPUT);

  gate.attach(SERVO_PIN);

  gate.write(0);

  Serial.begin(115200);
}

float getDistance() {

  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);

  digitalWrite(TRIG, LOW);

  duration = pulseIn(ECHO, HIGH);

  return duration * 0.034 / 2;
}

void loop() {

  distance = getDistance();

  if(distance < 20){

    digitalWrite(LED,HIGH);

    gate.write(90);

    delay(5000);

    if(getDistance() > 20){

      gate.write(0);

    }

    digitalWrite(LED,LOW);

  }

  delay(100);

}