Arduino - Cooling System using DS18B20 Temperature Sensor
In this tutorial, we are going to control temperature using a fan and DS18B20 temperature sensor. When the temperature is too hot, turn on the cooling fan. When the temperature is cool, turn off the cooling fan. If you want to use DHT11 or DHT22 instead of the DS18B20 sensor, see Arduino - Cooling System using DHT Sensor.
|1||×||Arduino UNO or Genuino UNO|
|1||×||USB 2.0 cable type A/B|
|1||×||Temperature Sensor DS18B20|
|1||×||4.7 kΩ resistor|
|1||×||12V Cooling Fan|
|1||×||12V Power Adapter|
Or you can use 5V Cooling Fan instead of 12V Cooling Fan. Even you use 5V Cooling Fan, you still need a relay and 5V Power Adapter. You can not power fan using 5V from Arduino.
About Cooling Fan and DS18B20 Temperature Sensor
The cooling fan used in this tutorial uses the 12v power supply. If power is supplied for the fan, the fan on and vice verse. To control fan by Arduino, we need to use a relay in between.
If you do not know about temperature sensor and fan (pinout, how it works, how to program ...), learn about them in the following tutorials:
Image is developed using Fritzing. Click to enlarge image
How System Works
- Arduino reads the temperature from the temperature sensor
- If the temperature exceeds an upper threshold, Arduino turn on the fan
- If the temperature falls below a lower threshold, Arduino turn off the fan
The above process is repeated infinitely in the loop.
If you want to turn on and turn off the fan when the temperature is above and below a specific value respectively, you just need to set the upper threshold and lower threshold to the same value.
Arduino Code for Cooling System with DS18B20 sensor
In the above code, the Arduino turn on the fan when the temperature exceeds 25°C, and keep the fan on until the temperature is below 20°C
- Connect Arduino to PC via USB cable
- Open Arduino IDE, select the right board and port
- On Arduino IDE, Go to Sketch Include Library Manage Libraries
- Search “OneWire”, then find the OneWire library by Paul Stoffregen
- Click Install button to install OneWire library.
- Search “Dallas”, then find the DallasTemperature library by Miles Burton.
- Click Install button to install DallasTemperature library.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Make enviroment around sensor hotter or colder
- See the state of fan
The above controlling method is the on-off controller, also known as a signaller or "bang-bang" controller. This method is very simple to implement.
There is an alternative method called the PID controller. With the PID controller, the desired temperature is more stable but very difficult to understand and implement. Therefore, the PID controller is not popular in temperature control.