#include <LiquidCrystal_I2C.h>
#define LDR_PIN 2
#define led 4
#define led2 3
// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;
LiquidCrystal_I2C lcd(0x27,20,4);

void setup() {
  pinMode(LDR_PIN, INPUT);
  pinMode(led,INPUT);

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

void loop() {
  int analogValue = analogRead(A0);
  float voltage = analogValue / 1042. * 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 ("Room: ");
  if (lux > 50) {
    lcd.print("light!");
    digitalWrite(led, LOW); //ไฟ
  } else {
    lcd.print("Dark");
    digitalWrite(led, HIGH); //ไฟ
  }
  if (lux > 30) {
    lcd.print("light!");
      digitalWrite(led2, LOW); //ไฟ
  } else {
    lcd.print("Dark");
    digitalWrite(led2, HIGH); //ไฟ
  }
  lcd.setCursor(0,1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("        ");
  
  delay(100);
}