#define ECHO_PIN 2
#define TRIG_PIN 3
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 20, 4);



void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(13, OUTPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  float distance = duration * 0.034 /2;
  float y = (1E-06*distance*distance) + (1.0055*distance) + 0.0012;

  //Serial.print("Jarak : ");
  //Serial.println(y);
  lcd.setCursor(0,3);
  lcd.print("Jarak: ");
  lcd.print(y);
  if (200 > y){
    lcd.setCursor(0,1);
    lcd.print("hati-hati");
    digitalWrite(13, HIGH);
    delay(y);
    digitalWrite(13, LOW);
    delay(y);
  }
  else{
    lcd.setCursor(0,1);
    lcd.print("         ");
  }
  delay(100);
}