const int sensorPin = A0;
const float baselineTemp = 20.0;

void setup() {
  // put your setup code here, to run once:

  Serial.begin(9600); // open a serial port, i.e. initialize the serial port to the desired speed

  for(int i = 2; i <= 4; i++) // initialize the digital pin directions and turn off
  {
    pinMode(i, OUTPUT);
    digitalWrite(i, LOW);
  }
}

void loop() {
  // put your main code here, to run repeatedly:

  // read the temperature sensor
  int sensorVal = analogRead(A0);  // float sensorVal = analogRead(sensorPin); / returns: 0-1023
  Serial.print("Sensor value: "); // send the temperature sensor values to the computer
  Serial.print(sensorVal);

  float voltage = (sensorVal / 1024.0) * 5.0; // convert the ADC reading (sensor reading) to voltage
  Serial.print(" , Volts: ");
  Serial.print(voltage);

  float temperature = (voltage - 0.5) * 100;  // convert the voltage to temperature in degrees
  Serial.print(" , Temperature - degrees C: ");
  Serial.println(temperature);

  if(temperature < baselineTemp)
  {
    /*for(int i = 2; i <= 4; i++)
    {
      digitalWrite(i, LOW);
    }*/
    digitalWrite(2, LOW);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  }
  else if((temperature >= baselineTemp + 2) && (temperature < baselineTemp + 4))
  {
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  }
  else if((temperature >= baselineTemp + 4) && (temperature < baselineTemp + 6))
  {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
  }
  else if(temperature >= baselineTemp + 6)
  {
   /* for(int i = 2; i <= 4; i++)
    {
      digitalWrite(i, HIGH);
    }*/
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
  }

  delay(250);
}