// -- RANGKAIAN PALANG PINTU OTOMATIS KERETA API

//Nama  : Rianda Saputra
//NIM   : 09030582226018

#define TRIG_PIN 2
#define ECHO_PIN 3
#define PIN_BUZZER 4
#define LED 5

#include <Servo.h>

Servo myservo;
int rotasi = 90;
int interval = 0;

float readDistanceCM(){
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034/2;
}

void led (bool state){
  digitalWrite(LED, state ? HIGH : LOW);
}
void soundBuzzer(){
  if(interval < 500){
    tone(PIN_BUZZER, 250);
    led(true);
  }else
  if(interval > 500){
    tone(PIN_BUZZER, 100,800);
    led(false);
  };
}
void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  Serial.begin(115200);
  pinMode(PIN_BUZZER, OUTPUT);
  pinMode(LED, OUTPUT);
  myservo.attach(6);
  myservo.write(90);
}

void loop() {
  tutupPalang();
  interval += 100;
  if(interval > 1000) interval = 0;
}

void tutupPalang(){
  float jarak = readDistanceCM();
  if(jarak > 0 && jarak < 100){
    soundBuzzer();
    tutup();
  }else{
    buka();
    noTone(PIN_BUZZER);
    led(false);
  }
}

void tutup(){
  if(rotasi <= 90){
    myservo.write(rotasi);
    delay(100);
    rotasi--;
  }
  if(rotasi <= 0) rotasi = 0;
}

void buka(){
  if(rotasi <= 90){
  myservo.write(rotasi);
  delay(100);
  rotasi+=4;
  }
  if(rotasi >= 90) rotasi = 90;
}