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

void setup() {
  Serial.begin(9600); // open a serial port
  for(int pinNumber = 2; pinNumber<5; pinNumber++){
    pinMode(pinNumber, OUTPUT);
    digitalWrite(pinNumber, LOW);
  }
}

void loop() {
  int sensorVal = analogRead(sensorPin);
Serial.print("Sensor Value: ");
Serial.print(sensorVal);
//convert the ADC reading to voltage
float voltage = (sensorVal/1024.0) * 5.0;
Serial.print(", Volts: ");
Serial.print(voltage);
Serial.print(", degrees C; ");
//convert the voltage to temperature in degrees
float temperature = (voltage - .5) * 100;
Serial.print(temperature);
if(temperature < baselineTemp+2){
  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){
  digitalWrite(2, HIGH);
  digitalWrite(3, HIGH);
  digitalWrite(4, HIGH);
}
delay(1);
}