#include <LiquidCrystal_I2C.h> 

int ldrPin = A0; 
int ledPin = 2; 
const float GAMMA = 0.7; 
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 16, 2); 

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

void loop() {
  // put your main code here, to run repeatedly:
  int ldrValue = analogRead(ldrPin); 
  float voltase = ldrValue / 1024. * 5; 
  float resistansi = 2000 * voltase / (1-voltase / 5);
  float kecerahan = pow(RL10 * 1e3 * pow(10, GAMMA) / resistansi, (1/GAMMA));

  lcd.setCursor(0, 0); 
  lcd.print("Cahaya: "); 
  if(kecerahan > 50){ 
    lcd.print("Terang"); 
    digitalWrite(ledPin, LOW); 
  }


  else{ 
    lcd.print("Gelap "); 
    digitalWrite(ledPin, HIGH); 
  }

  lcd.setCursor(0, 1); 
  lcd.print("Lux: ");
  lcd.print(kecerahan);
  lcd.print("     ");

  delay(100);
}