#include <LiquidCrystal_I2C.h>

const int trigPin = 7;
const int echoPin = 8;

long duration;
float distance;

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int greenLED = 10;
const int yellowLED = 11;
const int redLED = 12;

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

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

  pinMode(greenLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(redLED, OUTPUT);
}

void loop() {
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distance = duration * 0.034 / 2;

  if (distance > 15) 
  {
    digitalWrite(greenLED, HIGH);
    digitalWrite(yellowLED, LOW);
    digitalWrite(redLED, LOW);
  } 
  else if (distance >= 5 && distance <= 15) 
  {
    digitalWrite(greenLED, LOW);
    digitalWrite(yellowLED, HIGH);
    digitalWrite(redLED, LOW);
  } 
  else if (distance < 5)
  {
    digitalWrite(greenLED, LOW);
    digitalWrite(yellowLED, LOW);
    digitalWrite(redLED, HIGH);
  }

  lcd.setCursor(0, 0);
  lcd.print("Jarak: ");
  lcd.print(distance);
  lcd.print(" cm");

  delay(500);
}