#include <LiquidCrystal_I2C.h>
#define LED 2
int pirState = LOW;

// LDR Characteristics
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(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(0,0);
lcd.print("Cahaya: ");
if (lux > 50) {
  lcd.print("Terang!");
  digitalWrite(LED, LOW);

} else {
  lcd.print("Gelap ");
  digitalWrite(LED, HIGH);
}
lcd.setCursor(0,1);
lcd.print("lux: ");
lcd.print(lux);
lcd.print("       ");
delay(100);
}