Control a PWM Fan on a Raspberry Pi

Tested on Raspberry Pi 3B+ and 4B but should work on other versions as well.

Installation

Connect PWM capable Fan to GND, 5V and GPIO 12 (Pin 32)
Copy or link RPiFanControl.service to /etc/systemd/system/RPiFanControl.service
- sudo ln -s $PWD/RPiFanControl.service /etc/systemd/system/RPiFanControl.service
Copy or link RPiFanControl.py to /usr/local/bin/RPiFanControl.py
- sudo ln -s $PWD/RPiFanControl.py /usr/local/bin/RPiFanControl.py
Optional: Copy RPiFanControl.example.ini to /etc/RPiFanControl.ini and edit the config
- sudo cp RPiFanControl.example.ini /etc/RPiFanControl.ini
- sudo nano /etc/RPiFanControl.ini
Install python requirements
- Run sudo pip3 install -r requirements.txt
Enable system service
- Run sudo systemctl enable RPiFanControl
Add dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4 to /boot/config.txt and
Reboot your Pi

Once the script is running it will control the connected fan according to the settings.
See comments in RPiFanControl.py for details.

It will by default also update two files with the current values on each change:

/run/RPiFanControl/temperature contains the current CPU temperature in °C as a float
/run/RPiFanControl/dutycycle contains the current PWM duty cycle in % as an integer