Pi Cyclone

This is a script to control the active cooler fan on a Raspberry Pi 5.

At the time of writing, I'm running Ubuntu Server 23.10 and there have been issues integrating with the fan:

1. Fan speed control not working on Pi 5 under Ubuntu 23.10 - Fixed
2. Fan toggles on/off repeatedly - Fixed

The 2nd issue means that hysteresis is not working and the fan keeps going on and off at around 50°C. With a 5°C hysteresis, the fan is turned on at 50°C, it runs until the Pi cools down to 45°C. Without hysteresis, the fan turns off immediately the temperature goes below 50°C. A few seconds later, the Pi heats up a little and the fan turns on again... You get the idea.

Here are the results while my Pi 5 4GB is idle-ish (running home assistant on Docker Swarm, connected to the official active cooler fan and a 256GB SSD through a USB3.0 to SATA interface):

	Min (°C)	Mean (°C)	Max (°C)
No hysteresis	48.0	49.4	50.7
5°C hysteresis	44.1	47.2	50.1

Setup

(most of these actions require root access)

Install pinctrl from here if you don't have it already:

$ sudo apt-get update && sudo apt-get install build-essential cmake
$ git clone https://github.com/raspberrypi/utils.git
$ cd utils/pinctrl
$ cmake .
$ make
$ sudo make install

Install

Copy the cyclone.py script in this repository to your Raspberry Pi. You can use the secure copy protocol (scp) if you're doing this via SSH.

Make it executable:

$ sudo chmod +x cyclone.py

Create a service template (change the path to point to where you've stored the cyclone.py script):

[Unit]
Description = Pi Cyclone

[Service]
Type = simple
ExecStart = python3 /home/stephen/cyclone.py
User = root
Group = root
Restart = on-failure
SyslogIdentifier = pi-cyclone
RestartSec = 5
TimeoutStartSec = infinity

[Install]
WantedBy = multi-user.target

Save the file as pi-cyclone.service and place the file in your daemon service folder (usually /etc/systemd/system/).

Enable the service to start on boot and start it:

$ sudo systemctl enable pi-cyclone
Created symlink /etc/systemd/system/multi-user.target.wants/pi-cyclone.service → /etc/systemd/system/pi-cyclone.service.
$ sudo systemctl daemon-reload
$ sudo systemctl start pi-cyclone

To check that the script is running, run:

$ sudo systemctl status pi-cyclone
● pi-cyclone.service - Pi Cyclone
     Loaded: loaded (/etc/systemd/system/pi-cyclone.service; enabled; preset: enabled)
     Active: active (running) since Sun 2024-01-14 13:18:24 EAT; 1min 30s ago
   Main PID: 40454 (python3)
      Tasks: 1 (limit: 4592)
     Memory: 6.2M
        CPU: 104ms
     CGroup: /system.slice/pi-cyclone.service
             └─40454 python3 /home/stephen/cyclone.py

Jan 14 13:18:24 luna systemd[1]: Started pi-cyclone.service - Pi Cyclone.
Jan 14 13:18:24 luna pi-cyclone[40454]: 2024-01-14 13:18:24 INFO: Temperature = 51.6°C, current speed = 0%, new speed = 30%

Here are some logs after running stress --cpu 4 and letting the Pi cool down:

$ cat /var/log/pi-cyclone.log
2024-01-14 13:18:24 INFO: Temperature = 51.6°C, current speed = 0%, new speed = 30%
2024-01-14 13:21:40 INFO: Temperature = 44.4°C, current speed = 30%, new speed = 0%
2024-01-14 13:24:05 INFO: Temperature = 53.8°C, current speed = 0%, new speed = 30%
2024-01-14 13:24:35 INFO: Temperature = 60.4°C, current speed = 30%, new speed = 50%
2024-01-14 13:24:50 INFO: Temperature = 52.7°C, current speed = 50%, new speed = 30%
2024-01-14 13:28:05 INFO: Temperature = 44.4°C, current speed = 30%, new speed = 0%

You can check the CPU temperature yourself by running:

$ vcgencmd measure_temp
temp=46.6'C

To customize the setting while running the script, use the following options:

$ /home/stephen/cyclone.py --help
usage: cyclone.py [-h] [--low_speed_temp LOW_SPEED_TEMP] [--med_speed_temp MED_SPEED_TEMP] [--high_speed_temp HIGH_SPEED_TEMP] [--full_speed_temp FULL_SPEED_TEMP] [--hysteresis HYSTERESIS]

options:
  -h, --help            show this help message and exit
  --low_speed_temp LOW_SPEED_TEMP
                        Low fan speed temperature threshold (°C)
  --med_speed_temp MED_SPEED_TEMP
                        Medium fan speed temperature threshold (°C)
  --high_speed_temp HIGH_SPEED_TEMP
                        High fan speed temperature threshold (°C)
  --full_speed_temp FULL_SPEED_TEMP
                        Full fan speed temperature threshold (°C)
  --hysteresis HYSTERESIS
                        Hysteresis (°C)

Details

The script will run the following during operation (not necessarily in order):

Unload the pwm_fan driver:

$ sudo rmmod pwm_fan

You can then export and activate the pwm channel:

$ pinctrl FAN_PWM
45: a0    pd | hi // FAN_PWM/GPIO45 = PWM1_CHAN3
$ cd /sys/class/pwm/pwmchip0
$ echo 3 > export

You should now see /sys/class/pwm/pwmchip0/pwm3:

$ cd /sys/class/pwm/pwmchip0/pwm3 && ls
capture  duty_cycle  enable  period  polarity  power  uevent

Finally, you need to enable the channel:

$ echo 1 > enable

We're now be able to control the fan speed by updating the duty_cycle:

$ echo 10000 > duty_cycle

The maximum duty_cycle is:

$ cat period
41566

Credits to this StackExchange answer for the setup instructions.

Uninstall

Stop & disable the service:

$ sudo systemctl disable pi-cyclone
$ sudo systemctl stop pi-cyclone

Clean up the files:

$ sudo rm /etc/systemd/system/pi-cyclone.service
$ rm /home/stephen/cyclone.py

Disable the pwm channel:

$ cd /sys/class/pwm/pwmchip0/pwm3
$ echo 0 > enable

Load the pwm_fan driver:

$ sudo modprobe pwm_fan

Restart!

Resources

• Cooling Raspberry Pi 5
• Heating and cooling Raspberry Pi 5
• Disable automatic fan speed control of the Raspberry Pi 5 to control it manually
• Manual fancontrol on Raspberry Pi 5 for Ubuntu 23.10 64bit