#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
int merah = 7;
int kuning = 6;
int hijau = 5;
int triger = 4;
int echo = 3;

long bacaJarak(int triger, int echo){
  pinMode(triger, OUTPUT);
  digitalWrite(triger, LOW);
  digitalWrite(triger, HIGH);
  delayMicroseconds(10);
  digitalWrite(triger, LOW);
  pinMode(echo, INPUT);
  return pulseIn(echo, HIGH);
}

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

void loop() {
  lcd.clear();
  int cm = 0;
  cm = (0.03446 * bacaJarak(4, 3))/2;
  lcd.setCursor(0, 0);
  if(cm < 5){
    digitalWrite(merah, HIGH);
  }else if(cm <= 15){
    digitalWrite(merah, HIGH);
    digitalWrite(kuning, HIGH);
  }else if(cm > 15){
    digitalWrite(merah, HIGH);
    digitalWrite(kuning, HIGH);
    digitalWrite(hijau, HIGH);
  }
  lcd.print("Jarak : ");
  lcd.print(cm);
  delay(100);
}