A simple python script to control a PWM fan attached to your Raspberry Pi with one of the Pi's hardware PWM timers. These PWM timers are implemented in hardware so they don't take resources from the CPU, and their timing is far more predictable.
There are some caveats to using the hardware PWMs on a Pi. There are only two
channels available and both are in use for audio normally. See
/boot/overlays/README for more information. You must enable the pwm or the pwm-2chan
overlay for this to work.
Note: adjust these for your installation.
- Clone this repository
pip install -r requirements.txtcp hardware_pwm_fan /home/pi/scripts && chmod +x /home/pi/scripts/hardware_pwm_fan- Edit
hardware-pwm-fan.serviceto set your fan's set points - Copy and enable the systemd unit
sudo cp hardware-pwm-fan.service /etc/systemd/system
sudo systemctl daemon-reload
sudo systemctl enable hardware-pwm-fan.service --now
By default, GPIO 18 is used for PWM0 and 19 is used for PWM1, but these pins
share functions with PCM. GPIO 12 and 13 are better choices for PWM. Use
dtoverlay=pwm,pin=12,func=4 or dtoverlay=pwm,pin=13,func=4 if you want to
use those pins; otherwise you can just use dtoverlay=pwm. The -2chan variant
is if you want to configure both PWM channels for some reason.
This confuses me every time I try and set this. https://github.com/raspberrypi/firmware/blob/3a232374735c2bc5b7188ba2dfc0cbba8fa30d97/boot/overlays/README#L3250 has all of the info you need.