#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
int trig_pin = 2;
int echo_pin = 3;
const int merah = 12;
const int kuning = 11;
const int hijau = 10;
long echotime;
float Jarak;


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

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);
  }

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

  if(Jarak > 20)
  {
    digitalWrite(merah, LOW);
    digitalWrite(kuning, LOW);
    digitalWrite(hijau, HIGH);
  }

  delay(1000);
}

}