#include<Servo.h>

Servo gerbang;

const int trigPin =7;
const int echoPin =6;
const int ledMerah =3;
const int ledHijau =4;
const int buzzer =8;

void setup() {
  gerbang.attach(9);

pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);

pinMode(ledMerah, OUTPUT);
pinMode(ledHijau, OUTPUT);
pinMode(buzzer, OUTPUT);

gerbang. write(0);
digitalWrite(ledMerah, LOW);
digitalWrite(ledHijau, HIGH);
}

void loop() {
 // Kirim sinyal ultrasonik
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

// Baca pantulan
long durasi = pulseIn(echoPin, HIGH);

// Hitung jarak
int jarak = durasi * 0.034 / 2;

// Jika ada objek dekat
if (jarak < 20) {

gerbang.write(90);

digitalWrite(ledMerah, HIGH );
digitalWrite(ledHijau, HIGH);

tone(buzzer, 1000);

} else {

gerbang.write(0);

digitalWrite(ledMerah, HIGH);
digitalWrite(ledHijau, HIGH);

noTone(buzzer);

}
delay(500);
}