#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2);
int RelePin = 13;    
int inputPin = 9;               
int pirState = LOW;             
int val = 0;
#define SPEAKER_PIN 8
const int photoResistorPin = A0;
const float GAMMA = 0.7;
const float RL10 = 50;
float lux;
void setup() {
  pinMode(RelePin, OUTPUT);   
  pinMode(SPEAKER_PIN, OUTPUT);   
  pinMode(inputPin, INPUT);     
  lcd.init();
  lcd.backlight();
  lcd.clear();
}

void loop() {
  int analogValue = analogRead(photoResistorPin);
  float voltage = analogValue / 1024.0 * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));
  lcd.setCursor(0, 0);
  lcd.print("Light: ");
  lcd.print(lux);
  val = digitalRead(inputPin);  
  if (val == HIGH && lux < 300) {            
    digitalWrite(RelePin, HIGH);  
    if (pirState == LOW) {
      pirState = HIGH;
    }
  } else {
    digitalWrite(RelePin, LOW); 
    if (pirState == HIGH) {
      pirState = LOW;
    }
  }
}