int LedPin=13;
#include <LiquidCrystal_I2C.h>
#define LED 13

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

LiquidCrystal_I2C lcd(0x27, 16, 2); //alamat dari LCD I2C

void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  //data analog 0 sampai 5V
  int analogValue = analogRead(A0);

  float voltage = analogValue/1024.*5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  
  //perhitungan konversi ke lux meter
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  lcd.setCursor(1, 0);
  lcd.print("Cahaya: ");
  if (lux > 50) {
    lcd.print("Terang!");
    digitalWrite(LED, LOW);
  } else {
    lcd.print("Gelap ");
    digitalWrite(LED, HIGH);
  }
  lcd.setCursor(0,1); //tampilkan di baris kedua LCD
  lcd.print(lux); //tampilkan nilai lux
}