// Variables
int analogPin = A0;
int beta = 3950;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(analogPin, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  int value = analogRead(analogPin);
  float temperature = getAndPrintTemp(value);
  if (temperature >= 30){
    digitalWrite(13, HIGH);
  } else {
    digitalWrite(13, LOW);
  }

}

float getAndPrintTemp(int analog) {
  float celsius = 1 / (log(1 / (1023. / analog - 1)) / beta + 1.0 / 298.15) - 273.15;
  Serial.print("Temperature = ");
  Serial.print(celsius);
  Serial.print(" C");
  Serial.println();
  delay(1000);
  return celsius;
}