DDC/CI Multi-Monitor

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UUID: ddcci-multi-monitor@tim-we

Last edited:

3 weeks ago 2025-07-11, 07:42

Last commit: [524a797d] ddcci-multi-monitor@tim-we: Fix error when capabilities output has unknown characters (#7426)

Adjust monitor brightness via DDC/CI

README

DDC/CI Multi-Monitor

A Cinnamon applet that lets you adjust brightness of external monitors via DDC/CI.

Requirements

In order to function correctly this applet requires ddcutil.

It can be installed following these steps:

Install ddcutil and i2c-tools using:
```
sudo apt install ddcutil i2c-tools
```
To let ddcutil work without requiring root priviledges, the user must be part of the i2c group. Run the following command to add the current user to the i2c group.
```
sudo usermod -aG i2c $USER
```
After having executed the command, log out to apply the new configuration.

More information on how to install ddcutil can be found here in section "Tool 2".

You can check if ddcutil has been installed correctly and the monitor supports the DDC/CI protocol running:

ddcutil capabilities

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9 Comments

Jason Roner-1 month ago

Noice! Works with two LG 27UL500-W 4K monitors!

OldUncleMe-2 months ago

Scratch that: there's a separate place to enable spices/applets from the Cinnamon settings applet (aka: Settings|Applets). Even once downloaded and apparently installed, they must be enabled there to appear...seems like it would already be accomplished with the direction above -- maybe add these final steps?

OldUncleMe-2 months ago

ddcutil and i2c-tools installed, added the spice/applet: no icon on the panel, so essentially: what? Can't say if it works or not ....

Ivelin Banchev-8 months ago

Great job! Worked for me with this setup: - Ryzen 7 8845HS with 2x USB type C 3.2 gen 1 - 2xDell monitors daisy-chained + primary one connected to the first laptop's USB C port, which also charges the laptop - 1xArzopa monitor directly to the second laptop's USB C port, which also powers the monitor

Evan McBeth-10 months ago

Sweet little applet. Perfection in its simplicity.

Iván Legrán-10 months ago

Amazing applets! Thanks a lot!

k4100x-1 year ago

Thank you! This is always one of the first applets I add after a fresh Linux Mint install.

XIIIFaces-1 year ago

Absolutely great! Just what I was looking for! Everything works but I would request a feature if it's not too much hustle! Since I'm lazy to adjust 3 monitors in the evening is it possible to add a "general" slider for all monitors detected? That would be freaking awesome! I personally would love to see as well the "VCP code 0x14 (Select color preset): 6500 K (0x05) [...]" in the function list if that is anyhow possible just as an further improvement. With these too you could perfectly adjust your monitors for day and night use and the cherry on top would be to hook these settings to a timer but this is too much too ask for - just a general idea!

sta777ic-1 year ago

Followed directions but still got error. Fix/solution shown below. ~$ sudo apt install ddcutil i2c-tools [sudo] password for : Reading package lists... Done Building dependency tree... Done Reading state information... Done ddcutil is already the newest version (1.4.1-1). i2c-tools is already the newest version (4.3-2+b3). 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. ~$ sudo usermod -aG i2c $USER ~$ ddcutil capabilities No /dev/i2c devices exist. ddcutil requires module i2c-dev. Solution, Do these 2 extra steps as root, add i2c-dev into the /etc/modules-load.d/modules.conf modprobe i2c-dev