int Vo;
float R1 = 10000;
float logR2, R2, T, Tc, Tf;
float c1 = 1.009249522e-03, c2 = 2.378405444e-04, c3 = 2.019202697e-07;

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  Vo = analogRead(A0);
  delay(1);  // delay in between reads for stability
  R2 = R1 * (1023.0 / (float)Vo - 1.0);
  logR2 = log(R2);
  T = (1.0 / (c1 + c2*logR2 + c3*logR2*logR2*logR2));
  Tc = T - 273.15;
  Tf = (Tc * 9.0)/ 5.0 + 32.0; 

  Serial.print("Temperature: "); 
  Serial.print(Tf);
  Serial.print(" F; ");
  Serial.print(Tc);
  Serial.println(" C");
  // check for 40 = degree celcious
  if ( Tc > 40 ){
   // print out the value you read:
   digitalWrite(LED_BUILTIN, HIGH);  // turn the LED on (HIGH is the voltage level)
   delay(1000);                      // wait for a second
   digitalWrite(LED_BUILTIN, LOW);   // turn the LED off by making the voltage LOW
   delay(1000);
  }
  delay(250);
}