/*
  Photoresistor (LDR) Analog Demo

  Copyright (C) 2021 Uri Shaked.

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

#include <LiquidCrystal_I2C.h>

#define LDR_PIN 2

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;
int start=1;
int stop=2;
int yeen=0;
int LED=13;

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  pinMode(LDR_PIN, INPUT);
  pinMode(start,INPUT);
  pinMode(stop,INPUT);
  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));
  if(digitalRead(start)==1)
  {
  yeen=1;
  delay(100);
  }
  else if(digitalRead(stop)==1)
  {
    yeen=2;
    delay(100);
  }
  if(yeen==1)
  {
  lcd.setCursor(2, 0);
  lcd.print("Room: ");
  if (lux < 300) {
    lcd.print("DARK!");
    digitalWrite(LED, HIGH);
  } 
  else {
    lcd.print("Light!");
    digitalWrite(LED, LOW);
  }
  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");

  delay(100);
  }
  else if(yeen==2)
  {
    lcd.clear();
    digitalWrite(LED, LOW);
    delay(100);
  }
}