#include <LiquidCrystal.h>

const int LedPin = 7 ;
const float TempRef = 24 ;

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  lcd.clear();
  pinMode(LedPin , OUTPUT);
}

void loop() {
  int analogValue = analogRead(A0);
  float Temp = 1 / (log(1 / (1023. / analogValue - 1)) / 3950 + 1.0 / 298.15) - 273.15;
  
  lcd.setCursor(0 , 1);
  lcd.print("Temp = ");
  lcd.print(Temp);
  lcd.println(" C");
  delay(1000);  
  
  digitalWrite(LedPin, LOW);
  if ( Temp- TempRef >= 2 || TempRef - Temp >= 2  ){ 
    digitalWrite(LedPin, HIGH);
  } 
}