Only 1 pen button works on many Huion models

[tysontan]

Today I visited Huion's flagship store near their Shenzhen headquarter. I have tested every model being showcased in the store. Every model worked out-of-the-box with pointing and drawing, but not the pen buttons.

Only the older Kamvas Pro 24, and other pen displays from the same generation with PenTech 3.0 pens, have 2 functional pen buttons.

All newer pen displays, e.g. Kamvas Pro 19/27 with PenTech 3.0+/4.0, and all graphics tablets, have only 1 side button working -- the lowest button, which is mapped to middle button click by default.

I'm using Manjaro with Linux 6.10. In Krita's Tablet Tester, the non-functional buttons have no input event at all. Remapping buttons using xinput could only affect the one working button. I tried to install 6.11 kernel and the digimend 13 dkms AUR package, they didn't help at all.

What can I do to get them working? I can collect information for you when I visit the place next time. I live very close to Shenzhen. Please tell me what do you need and how do I collect them for you.

[waterlubber]

I have the same issue with a newly purchased Huion Frego (L610). Only one button works.

The button states are visible in the USB data stream .

001:012:000:STREAM             1735616891.193355
 08 80 E2 B3 70 36 00 00 00 00 00 F7

Hex value "80" appears to contain a button bitmask. 1 for the stylus tip, 2 for button 1 (working), and 4 for button 2.

It appears the next four bytes (E2 B3 70 36) encode positon (two bytes x, two bytes y).
The next two bytes (00 00) encode pressure.

The next byte is 00 always.

The last two bytes encode pen tilt. Not sure about sign/complement but they separately encode tilt about x and y axes.

It is likely that this could be made to work with a simple driver update. I am on Arch Linux/KDE/Wayland. xev does not detect the second button.

Edit: I have had some success with opentabletdriver. I do not think DIGImend is maintained as much any more, @tysontan.
The following procedure should get both buttons working for you; this is now working fine on my machine.

• install opentabletdriver
• save this contents to /etc/udev/rules.d/50-huion.rules

SUBSYSTEMS=="usb",ATTRS{idVendor}=="256c",MODE:="0666"
SUBSYSTEM=="input", KERNEL=="event*",ATTRS{name}=="HUION 256C PEN STYLUS",MODE:="0666"

• copy the Configurations_L610.json file from this post to ~/.config/OpenTabletDriver`
  Add support for Huion L610 OpenTabletDriver/OpenTabletDriver#3505 (comment)