/*
  Photoresistor (LDR) Analog Demo

  Copyright (C) 2021 Uri Shaked.

  https://wokwi.com/arduino/projects/305193627138654786
*/

#include <LiquidCrystal_I2C.h>

int led=2 ;

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

LiquidCrystal_I2C lcd(0x27, 16,2);

void setup() {
  pinMode(led,OUTPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  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(2, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");
  delay(100);
}