#include <LiquidCrystal_I2C.h>

#define LED 2

const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

void setup()
{
  pinMode(LED, OUTPUT);

  lcd.init(); // initialize the lcd
  lcd.backlight();

  //lcd.setCursor(0, 0);         // move cursor to   (0, 0)
  //lcd.print("Arduino");        // print message at (0, 0)
  //lcd.setCursor(2, 1);         // move cursor to   (2, 1)
  //lcd.print("GetStarted.com"); // print message at (2, 1)
}

void loop()
{
  int analogValue = analogRead(A0);
  float voltage = analogValue/1024. * 5 ;
  float resistance = 2000*voltage/(1-voltage/5);
  float lux = pow (RL10 *1e3*pow(10, GAMMA)/resistance,(1/GAMMA));

  lcd.setCursor(0, 0);
  lcd.print("Cahaya : ");
  if(lux > 50){
	  lcd.print("Terang");
	  digitalWrite(LED,LOW);
  } else {
	  lcd.print("Gelap");
	  digitalWrite(LED,HIGH);
  }
  lcd.setCursor(0, 1);
  lcd.print("Lux : ");
  lcd.print(lux);
  //lcd.print(" ");
  delay(100);
}