//Kombinasi 11 (Sensor Ultrasonik, servo, buzzer)
//Aplikasi palang pintu kereta api
//Menggunakan bool
//Jika kereta mendekat pada jarak tertentu, maka buzzer akan menyala,
//dan servo akan bergerak
//dan pada Serial monitor muncul tulisan Ada Kereta
//Jika sudah menjauh, maka buzzer padam, servo kembali seperti sebelumnya
//dan pada Serial monitor muncul tulisan Aman
//Link Wokwi : https://wokwi.com/projects/334789504912065108

#include <Servo.h>
#define trigPin 2
#define echoPin 3
#define buzzerPin 5

Servo myservo;

int val;

float readDistanceCM()
{
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigger pin to HIGH state for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  int duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2;
}

void setup() {
Serial.begin(115200);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(buzzerPin, OUTPUT);
myservo.attach(9);

}

void loop() {
  float distance = readDistanceCM();
  bool z = distance<100;

  if (z==true){
  myservo.write(90);       
    tone(buzzerPin, 500);
    delay(1000);
    tone(buzzerPin, 800);
    delay(1000);
    Serial.println("Ada Kereta");
  }
  else{
    myservo.write(0);    
    noTone(buzzerPin);
    Serial.println("Aman");

  }
delay(100);
}