#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
int trig_pin = 8;
int echo_pin = 9;
long echotime;
float Jarak;
const int merah = 12;
const int kuning = 10;
const int hijau = 8;

void setup() 
 {
  lcd.init();
  lcd.backlight();
  pinMode (trig_pin, OUTPUT);
  pinMode (echo_pin, INPUT);
  pinMode(merah, OUTPUT);
  pinMode(kuning, OUTPUT);
  pinMode(hijau, OUTPUT);
 }

void loop() 
{
  digitalWrite (trig_pin, HIGH);
  delayMicroseconds (10);
  digitalWrite (trig_pin, LOW);
  echotime= pulseIn(echo_pin, HIGH);
  Jarak = 0.0001*((float)echotime*340.0)/2.0;

  lcd.clear();
  lcd.setCursor (0,0);
  lcd.println ("Jarak : ");
  lcd.print(Jarak);
  if (Jarak < 11)
  {
  digitalWrite(merah, HIGH);
  digitalWrite(kuning, LOW);
  digitalWrite(hijau, LOW);
  }

 else if (Jarak > 11 && Jarak < 20)
  {  
  digitalWrite(merah, LOW);
  digitalWrite(kuning, HIGH);
  digitalWrite(hijau, LOW);
  }
  else if (Jarak > 20)
  {  
  digitalWrite(merah, LOW);
  digitalWrite(kuning, LOW);
  digitalWrite(hijau, HIGH);
  }
  delay(1000);
}