DDC Tool

Tool to control monitors using Display Data Channel (DDC).

Abstract

This tool started from a need to control my monitors using DDC; Since switching to dark theme, I often get discomfort from any page/presentation/online meeting using a white background, and needed a quick way to control the backlight.

This a a WIP and many changes are likely coming in the near future. I’m committing this version so I can start breaking stuff…

Prerequisites

To use this, you need the i2c-dev module. Add the following lines to /etc/modules:

# Used to control monitors using ddc
i2c-dev

Since the script requires root, you need to use a tool like sudo to execute it as root. Assuming you already have a @includedir /etc/sudoers.d line in your /etc/sudoers file, cou can add/update /etc/sudoers.d/ddctool with the following command:

printf '0i\n%%users\tALL=(root) NOPASSWD: %s\n\n.\n.,$d\nw\nq\n' "/opt/ddctool.sh" |
    SUDO_EDITOR="ed -s" visudo -f /etc/sudoers.d/ddctool

The last argument to printf is the script location, review as needed.

`ddctool.sh`

TODO - usage may change significantly

TODO

Check if udev rules can be used to trigger module load
Support per-monitor setting
Add more commands: list, report, etc…