#include <LiquidCrystal_I2C.h>
#define led 2

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

LiquidCrystal_I2C lcd (0x24, 20,4);
void setup() {
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");
   digitalWrite (led, LOW  );
 }
   else {
     lcd.print ("Gelap  ");
     digitalWrite (led, HIGH );
   }

lcd.setCursor(0, 1);
lcd.print ("Lux: ");
lcd.print ("         ");
delay (100);
 }