#include <LiquidCrystal_I2C.h>
// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;
LiquidCrystal_I2C lcd(0x27, 20, 4);
void setup() {
  lcd.init();
  lcd.backlight();
}
void loop() {
  int analogValue = analogRead(A1);
  float voltage = analogValue / 1024.0 * 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("Kamar: ");
  if (lux > 50) {
    lcd.print("Terang");
  } else {
    lcd.print("Gelap  ");
  }
  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  delay(100);
}