How to run Geekworm x735 script on Freedombox

Published: 2026-04-06

Overview

When I installed the x735 script by the official guide to FreedomBox, then the fan of my X735 V2.5 Power Management Board was not rotating at all.

See below the hardware and software specification when I struggled with this problem.

Hardware kit:

$ sudo dmesg | grep -i rasp
[    0.000000] Machine model: Raspberry Pi 4 Model B Rev 1.4

$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 13 (trixie)
Release:        13
Codename:       trixie

$ uname -a
Linux freedombox 6.12.74+deb13+1-arm64 #1 SMP Debian 6.12.74-2 (2026-03-08) aarch64 GNU/Linux

Errors

Errors which I’ve got during testing…

$ sudo python3 pwm_fan_control.py
Traceback (most recent call last):
x735-script/pwm_fan_control.py", line 10, in <module>
IO.setup(servo,IO.OUT)
RuntimeError: Mmap of GPIO registers failed

How to solve

Firstly I will show outputs which could affect the function of the fan x735 v2.5.

$ ls /sys/class/pwm/
pwmchip0

$ ls /sys/class/pwm/pwmchip0
device  export  npwm  power  pwm1  subsystem  uevent  unexport

$ sudo dmesg | grep -i pwm

$ sudo dmesg | grep -i overlay

$ ls /boot/firmware/overlays/
hifiberry-dac.dtbo  pi4-spidev.dtbo  README.md

By the last command is obvious there are only two overlays installed by default. None of these seems as the right one for pwm-2chan.

Solution

The solution is to add missing overlay, because when I add all available pwm* overlays from GitHub raspberry then the fan started rotate!

The problem is that I do not know how to properly add the overlays to the system if should be - the whole kernel recompiled with new overlays, or - there is some interface/framework for adding the overlays, or - download the raw file from GitHub raspberry to /boot/framework/overlays is just enough

I choosed the last one as the simplest one for me.

curl -s https://api.github.com/repos/raspberrypi/firmware/contents/boot/overlays |
jq -r '.[] | select(.name | startswith("pwm")) | "\(.download_url)"' |
wget -i - -P /boot/firmware/overlays/

The command above will download all overlays which begin with pwm. Honestly not all of these are required, but I do not have a time tested by one by one or some right combination of files, but just the file pwm-2chan.dtbo did not work for me so I downloaded all these files and the fan start correctly rotating.

Other tips

Do not edit /boot/firmware/config.txt directly, then udpate could rewrite this file on debian and fan will stop working.

Instead edit the /etc/default/raspi-firmware-custom as is adviced in /boot/firmware/config.txt

$ cat /boot/firmware/config.txt
# Do not modify this file!
#
# It is automatically generated upon install or update of either the
# firmware or the Linux kernel.
#
# If you need to set boot-time parameters, do so via the
# /etc/default/raspi-firmware, /etc/default/raspi-firmware-custom or
# /etc/default/raspi-extra-cmdline files.

$ cat /etc/default/raspi-firmware-custom
# configuration for x735 script of geekworm
dtoverlay=pwm-2chan,pin2=13,func2=4

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