#include <LiquidCrystal_I2C.h>

#define LED 2 

// LDR Chatacteristics
const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 20 ,4);

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

  lcd.init();
  lcd.backlight();

}

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(2,0 );
  lcd.print("Cahaya: ");
  if (lux > 50) {
    lcd.print("Terang: ");
    digitalWrite(LED, LOW);
  }else{
    lcd.print("Gelap: ");
    digitalWrite(LED, HIGH);
  }
}