#include <LiquidCrystal_I2C.h>

#define LED 2
//LDR KARAKTERISTIK
const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27 , 20 , 4);
void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);

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

void loop() {
  // put your main code here, to run repeatedly:
  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 BENDERANG!!");
    digitalWrite(LED,LOW);
  }else{
    lcd.print("GELAP BG!!");
    digitalWrite(LED, HIGH);
  }
}