arduino-project-2.ino

const int sensorPin = A0;
const float baselineTemp = 25.0;

void setup() {
  Serial.begin(9600);
  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);

  // Now we can actually convert this value to volts by getting the ratio
  // 1023 is 5V, 0 is 0, so ratio in between
  float voltage = (sensorVal / 1024.0) * 5.0;
  Serial.print(", Volts: ");
  Serial.print(voltage);

  // Convert using datasheet to C.  10 millivolts of change is equivalent to a temp change of 1 degree science
  // Offset for negative temperatures
  Serial.print(", degrees C: ");
  float temperature = (voltage - 0.5) * 100;
  Serial.println(temperature);

  if (temperature < baselineTemp) {
    digitalWrite(2, LOW);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  } else if (temperature >= baselineTemp && temperature < baselineTemp + 2) {
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  } else if (temperature >= baselineTemp + 2 && temperature < baselineTemp + 4) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
  } else if (temperature >= baselineTemp + 4) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
  }

  delay(10);
}