#define echoPin 2
#define trigPin 3
#include <LiquidCrystal_I2C.h>

int maximumRange = 50;
int minimumRange = 00;
long duration, distance;

int LED_merah = 7;
int LED_hijau = 8;

int buzzer = 4;
LiquidCrystal_I2C lcd(0x27, 16, 2 );

void setup() 
{
    Serial.begin (9600);
  pinMode(trigPin, OUTPUT); 
  pinMode (echoPin, INPUT);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("batas jarak ");
  
  lcd.setCursor(0, 1);
  lcd.print("pengunjung");
  delay(2000);
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("batas jarak:");
  
  lcd.setCursor(0, 1);
  lcd.print("50 cm");

  delay(3000);
  lcd.clear();


  pinMode(LED_hijau, OUTPUT);
  pinMode(LED_merah, OUTPUT);

  pinMode(buzzer, OUTPUT);
}

void loop() 
{

  /* Penentuan jarak. */
  digitalWrite(trigPin, LOW); 
  delay(50); 
  digitalWrite(trigPin, HIGH); 
  delay(10); 
  digitalWrite(trigPin, LOW);

  duration= pulseIn(echoPin, HIGH);



  //perhitungan untuk dijadikan jarak

  distance = duration/58.2;

  //perhitungan untuk dijadikan jarak distance = duration/58.2;

  /* Jika jarak melebihi 300 cm, kirim keterangan "Di luar jangkauan" */

  if (distance >= maximumRange || distance <= minimumRange)
  { 
    lcd.setCursor(0, 1);
    lcd.print("JARAK AMAN");
    lcd.setCursor(0, 0);
    lcd.print("jarak:");
    lcd.print(distance);
    lcd.print(" cm ");

    digitalWrite(LED_hijau, HIGH);
    digitalWrite(LED_merah, LOW);
    delay(500);
  }

    else 
    {

    /*
    Kirim hasil pembacaan jarak melalui serial monitor
    */
    lcd.setCursor(0, 0);
    lcd.print("jarak:");
    lcd.print(distance);
    lcd.print(" cm ");
    lcd.setCursor(0, 1);
    lcd.print("MENJAUH");

    tone(buzzer, 384);

    delay(500);

    noTone(buzzer);

    digitalWrite(LED_merah, HIGH);
    digitalWrite(LED_hijau, LOW);


    

    }

}