#include <Wire.h>
#include <LiquidCrystal_I2C.h>

const int trigPin = 9;
const int echoPin = 6;
const int buzzerPin = 12;

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Parkir Mundur");
}

void loop() {
  long durasi;
  int jarak;

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  durasi = pulseIn(echoPin, HIGH);
  jarak = durasi * 0.034 / 2;

  lcd.setCursor(0, 1);
  lcd.print("Jarak: ");
  lcd.print(jarak);
  lcd.print(" cm  ");
  if (jarak > 0 && jarak < 100) {
    int waktuBuzzer = map(jarak, 5, 100, 50, 800);
    tone(buzzerPin, 1000);
    delay(waktuBuzzer);
    
  } else {
    noTone(buzzerPin);
  }

  delay(100);
}