#include <LiquidCrystal_I2C.h>
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() {
Serial.begin(9600);
pinMode(inputPin, INPUT);  
pinMode(13, 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));
    val = digitalRead(inputPin); 

  lcd.setCursor(1,1);
if ( val == HIGH && lux > 30) {            
      if (pirState == LOW) {
      digitalWrite(13, HIGH);
      lcd.println("ADA GERAKAN");
      pirState = HIGH;
    }
  } else {
      if (pirState == HIGH) {
      digitalWrite(13, LOW);
      lcd.println(" TIDAK ADA GERAKAN");
      pirState = LOW;
    }
  }
  lcd.setCursor(3,0);
  lcd.println(" lux:");
  lcd.print(lux);
  delay(100);
}