Getting a PWM fan running on a Ubuntu Raspberry Pi 4

Collection of scripts to control the PWM fan speed on my Ubuntu 22.04 Raspberry Pi 4. Details of the PWM fan case and also sample demo Python scripts I used as a base can we found on the PI4-FAN-PWM Wiki page. To create the actual service creation part I drew insparation from a medium.com article

Note: I know thsi is not the most efficient code and will optimise it when I have some more time.

Creating the relevant Python script on your Raspberry Pi

1. Create a scripts folder, in my case it is under the /home/$USER/ folder.

   mkdir scripts
   

2. Change to the scripts folder and then create a fan_service.py file and dump the contents of the fan_service.py file

   cd scripts
   vi fan_service.py
   

3. You will also install the relevant Python Raspberry Pi GPIO dependancies using pip

   sudo apt update
   pip install RPi.GPIO
   pip install gpiozero
   

4. The you should be ready to test the script. If you want to see the actual temrature and current fan speed make sure to uncomment the each # print line in the fan_service.py file

   sudo python fan_service.py
   

Now lets create a service

1. Now create the service so that the script automaticall starts on reboot and no manual intervention is needed. Make sure you copy over the contents of the fan.service file that is part of this repo. Make sure to replace the $USER attrivute with your username where the script is stored

   sudo nano /etc/systemd/system/fan.service 
   

2. Now we need to reload the daemon

   sudo systemctl daemon-reload
   

3. Let’s enable enable the service

   sudo systemctl enable fan.service
   

4. Starting the service.

   sudo systemctl start fan.service
   

Other userful service commands There are several commands you can do to start, stop, restart, and check status.

1. To stop the service.

   sudo systemctl stop fan.service
   

2. To restart.

   sudo systemctl restart fan.service
   

3. To check status.

   sudo systemctl status fan.service