Open PWM on RockPi4 to control fan on PoE HAT

[dolphs]

Hi, 

 

Based on this topic it should be possible to open PWM0 and PWM1 on a  RockpiS,

 

Yet I like to do the same thing on a Rockpi4A+ ( fdtfile=rockchip/rk3399-rock-pi-4a-plus.dtb ),

in order to enable the fan on a PoE HAT

 

Without any overlay it shows:

root@rockpi-4a:/sys/class/pwm# ls /sys/class/pwm/ -la
total 0
drwxr-xr-x  2 root root 0 Mar 19 05:20 .
drwxr-xr-x 71 root root 0 Mar 19 05:20 ..
lrwxrwxrwx  1 root root 0 Mar 19 05:20 pwmchip0 -> ../../devices/platform/ff420020.pwm/pwm/pwmchip0

 

I tried some of radxa's suggestions using their " rockpi-poe.dtbo " overlay ( user_overlays=rockpi-poe ) 

and indeed that makes the fan spinning up like crazy, but alas unable to control the fan, due to missing libmraa.

However the overlay mentioned does seem to open two additional PWM's, thus PWM0 till 2.

 

root@rockpi-4a:~# ls /sys/class/pwm/ -la
total 0
drwxr-xr-x  2 root root 0 Mar 19 05:36 .
drwxr-xr-x 71 root root 0 Mar 19 05:36 ..
lrwxrwxrwx  1 root root 0 Mar 19 05:36 pwmchip0 -> ../../devices/platform/ff420000.pwm/pwm/pwmchip0
lrwxrwxrwx  1 root root 0 Mar 19 05:36 pwmchip1 -> ../../devices/platform/ff420010.pwm/pwm/pwmchip1
lrwxrwxrwx  1 root root 0 Mar 19 05:36 pwmchip2 -> ../../devices/platform/ff420020.pwm/pwm/pwmchip2

 

I was wondering if this is WIP, or should is it possible already to enable pwm with a built-in armbian overlay,

was unable to retrieve anything in that direction from: /boot/dtb/rockchip/overlays except for " overlays=w1-gpio " but perhaps there is another way?

 

[    6.207083] OF: /onewire@0: could not get #gpio-cells for /vop@ff900000/port/endpoint@1
[    6.207102] w1-gpio onewire@0: gpio_request_one (ext_pullup_enable_pin) failed
[    6.207105] w1-gpio: probe of onewire@0 failed with error -22

 

 

PS I am not demandig anything, just asking about PoE HAT status ( controllable fan ) in current armbian ( edge, kernel 5.16.x ) and if this is WIP?

 

thanks!

[dolphs]

I compiled a small HOWTO to get this going with kernel 5.16 on a Rockpi4+

 

sudo su -
apt update && apt -y install git build-essential swig4.0 python3-dev libnode-dev cmake libjson-c-dev

 

 

Grab "user overlay" from radxa: 

mkdir -p /boot/overlay-user
cd /boot/overlay-user
curl -sL https://rock.sh/rockpi-poe-dtbo -o rockpi-poe.dtbo

nano /boot/armbianEnv.txt 
  user_overlays=rockpi-poe

exit

 

Compile mraa packages

cd /home/[user]

git clone https://github.com/eclipse/mraa

mkdir mraa/build
cd mraa/build

cmake ..
make -j7  #depends on cores available+1

sudo make install

 

Spoiler

---
< snip snip >
[ 97%] Linking C executable mraa-i2c
[ 98%] Linking CXX executable iio_cpp
[100%] Linking C executable mraa-gpio
[100%] Built target mraa-i2c
[100%] Built target uart_ow_cpp
[100%] Built target mraa-gpio
[100%] Built target iio_cpp
---

---
<snip snip>
[ 92%] Built target uart_ow_cpp
[ 95%] Built target mraa-uart
[ 97%] Built target mraa-i2c
[100%] Built target mraa-gpio
Install the project...
-- Install configuration: ""
-- Installing: /usr/local/include/mraa.h
-- Installing: /usr/local/include/mraa.hpp

<snip snip>
-- Installing: /usr/local/share/mraa/examples/c++/spi.cpp
-- Installing: /usr/local/share/mraa/examples/c++/pwm.cpp
-- Installing: /usr/local/share/mraa/examples/c++/led.cpp
-- Installing: /usr/local/bin/mraa-gpio
-- Set runtime path of "/usr/local/bin/mraa-gpio" to ""
-- Installing: /usr/local/bin/mraa-i2c
-- Set runtime path of "/usr/local/bin/mraa-i2c" to ""
-- Installing: /usr/local/bin/mraa-uart
-- Set runtime path of "/usr/local/bin/mraa-uart" to ""
---

 

 

Install PoE package and enable its service 

sudo su 

#view /etc/ld.so.conf.d/libc.conf
ldconfig # add /usr/local/lib libraries to " LD_LIBRARY_PATH "

cd /tmp
wget https://cos.setq.me/rockpi/deb/rockpi-poe-0.13.deb
dpkg -i rockpi-poe-0.13.deb

systemctl enable rockpi-poe.service

reboot

 

 

After reboot the fan should spin up like mad and after little while it slows down ( off ) :

root@rockpi-4a:~# systemctl status rockpi-poe.service
● rockpi-poe.service - Rockpi PoE-FAN
     Loaded: loaded (/lib/systemd/system/rockpi-poe.service; enabled; vendor preset: enabled)
     Active: active (running) since Tue 2022-03-22 11:19:06 UTC; 11min ago
   Main PID: 659 (python3)
      Tasks: 1 (limit: 4464)
     Memory: 11.7M
        CPU: 264ms
     CGroup: /system.slice/rockpi-poe.service
             └─659 /usr/bin/python3 /usr/bin/rockpi-poe.py start

Mar 22 11:19:06 rockpi-4a systemd[1]: Started Rockpi PoE-FAN.
Mar 22 11:19:08 rockpi-4a libmraa[659]: libmraa version v2.2.0-11-gd7ae171 initialised by user 'root' with EUID 0
Mar 22 11:19:08 rockpi-4a libmraa[659]: gpio: platform doesn't support chardev, falling back to sysfs
Mar 22 11:19:08 rockpi-4a libmraa[659]: libmraa initialised for platform 'ROCK Pi 4' of type 20

 

 

 

[tparys]

If the sysfs pwm device is showing up, I'm not following why you'd need libmraa to access it?

 

If you'd like to have fewer moving parts, you should be able to do this entirely via DTB. I posted something similar for the fan on the NanoPI M4 metal case. https://forum.armbian.com/topic/17022-automatic-kernel-control-of-nanopi-m4-m4v2-metal-case-fan/

 

It was based on some earlier work the Kobol guys did for one of their NAS systems. You basically define the PWM as a fan control, give it a few operating levels, and tell the kernel that it's a cooling device for the CPUs.

 

I also learned that depending on the PWM frequency, it can also create audible tones, which may or may not be desirable. You can also have it play music too, should you be so entertained ... https://forum.armbian.com/topic/19050-playing-with-a-fan-on-an-nanopi-m4v2/