#include <LiquidCrystal_I2C.h>

#define LDR_PIN 32

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  Serial.begin(115200);
  pinMode(LDR_PIN, INPUT);

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

void loop() {
  int analogValue = analogRead(32);
    Serial.print("analogValue");
    Serial.println(analogValue);
    Serial.println("        ");

  float voltage = analogValue / 4069. * 3.3;
    Serial.print("voltage: ");
    Serial.println(voltage);
    Serial.println("        ");
    
  float resistance = 3000 * voltage / (1 - voltage / 3.3);
    Serial.print("resistance: ");
    Serial.println(resistance);
    Serial.println("         ");
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  lcd.setCursor(2, 0);
  lcd.print("Room: ");
  if (lux > 50) {
    lcd.print("Light!");
  } else {
    lcd.print("Dark  ");
  }

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

  delay(100);
}