#include <LiquidCrystal_I2C.h>
#define LDR_PIN 2
const float GAMMA = 0.7;
const float RL10 = 50;
int start = 2;
int reset = 3;
int palm = 0;

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(LDR_PIN, INPUT);
  pinMode(13 ,OUTPUT);
  pinMode(3 ,INPUT);
  pinMode(2 ,INPUT);
  lcd.init();
  lcd.backlight();
  Serial.begin(115200);
}

void loop() {
   if (digitalRead(start) == 1)
  {
    palm = 1; 
    delay(100);
    Serial.println("start"); 
  }
  else if (digitalRead(reset) == 1)
  {
    palm = 2; 
    delay(100);
    Serial.println("EMERGENCY STOP!");
  }
  int analogValue = analogRead(A3);
  float voltage = analogValue / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));
if (palm == 1)
{
  lcd.setCursor(3, 0);
  lcd.print("Room: ");
  if (lux < 300) {
    lcd.print("DARK ");
    digitalWrite(13, HIGH);
  } else {
    lcd.print("LIGHT");
    digitalWrite(13, LOW);
  }

  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");

  delay(100);
}
else if (palm == 2)
 {
   lcd.clear();
   digitalWrite(13 , LOW);
   delay(100);
 }
}