#include <LiquidCrystal_I2C.h>
#define Led 2

// LDR Characteristic
const float GAMMA = 0.7;
const float RL10 = 50;
LiquidCrystal_I2C lcd (0x27, 20, 4);

int inputPin = 3;
int pirState = LOW;
int val = 0;

void setup() {
  pinMode (Led, OUTPUT);
  pinMode (inputPin, INPUT);
  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 (2, 0);
  lcd.print ("Cahaya :");
  if (lux > 50){
    lcd.print ("Terang!");
    digitalWrite (Led, LOW);
    lcd.setCursor (0, 1);
    lcd.print("LUX :");
    lcd.print(lux);
    lcd.setCursor (10, 1);
    lcd.print("     ");
  }
  else{
    lcd.print ("Gelap  ");
    digitalWrite (Led, HIGH);
    val = digitalRead (inputPin);    
  if (val == HIGH)
  {
    if (pirState == LOW)
    {
      lcd.setCursor (0, 1);
      lcd.print ("Ada Gerakan     ");
      pirState = HIGH;
    }
  }
    else
    {
      if (pirState == HIGH)
      {
        lcd.setCursor (0, 1);
        lcd.print ("Tidak ada Gerak ");
        pirState = LOW;
      }
    }
  }
}