# asdbctl

**Repository Path**: git/asdbctl

## Basic Information

- **Project Name**: asdbctl
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-04-08
- **Last Updated**: 2026-04-08

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

Apple Studio Display Brightness Control
+++++++++++++++++++++++++++++++++++++++
This small command line utility allows for changing the brightness of one or
more Apple Studio Display(s) attached to a Linux or Windows PC.

.. code-block::

    Tool to get or set the brightness for Apple Studio Displays

    Usage: asdbctl [OPTIONS] <COMMAND>

    Commands:
      get   Get the current brightness in %
      set   Set the current brightness in %
      up    Increase the brightness
      down  Decrease the brightness
      help  Print this message or the help of the given subcommand(s)

    Options:
      -s, --serial <SERIAL>  Serial number of the display for which to adjust the brightness
      -h, --help             Print help

Getting started
---------------
Prebuild releases are not available. Only Rust is required to build from source.

.. code-block:: bash

    git clone https://github.com/juliuszint/asdbctl.git && cd asdbctl
    # either just run from here
    cargo run --release -- help
    # or install with
    cargo install --path .

Troubleshooting
---------------
In case regular users are not allowed to access raw HID devices, you can use the
udev rule in the `rules.d` directory.

Technical details
-----------------
Dumping the USB traffic on macOS with Wireshark and setting the proper filters
will show the USB Control transfers to set the brightness

.. code-block::

    bmRequestType: 0x21
    bRequest     : 0x9
    wValue       : 0x0301
    wIndex:      : 0x000c
    wLength      : 0x7

with this data package when setting it to the minimum brightness value

.. code-block::

    [ 0x01, 0x90, 0x01, 0x00, 0x00, 0x00, 0x00 ]

The ``0x90`` and ``0x01`` are the brightness value encoded with the least
significant byte first (LSB).

Its possible to operate the Studio Display in 3 different USB configurations
and Linux will use the first. This means that the USB interface number for
controlling the brightness is not ``0xc`` (extracted from the dump) but ``0x7``.

Decoded HID Report Descriptor
-----------------------------

.. code-block::

    Apple Studio Display HID report descriptor

    # device 0:0
    # 0x05, 0x80,                    // Usage Page (Monitor)                0
    # 0x09, 0x01,                    // Usage (Monitor Control)             2
    # 0xa1, 0x01,                    // Collection (Application)            4
    # 0x85, 0x01,                    //  Report ID (1)                      6
    # 0x06, 0x82, 0x00,              //  Usage Page (VESA Virtual Controls) 8
    # 0x09, 0x10,                    //  Usage (Brightness)                 11
    # 0x16, 0x90, 0x01,              //  Logical Minimum (400)              13
    # 0x27, 0x60, 0xea, 0x00, 0x00,  //  Logical Maximum (60000)            16
    # 0x67, 0xe1, 0x00, 0x00, 0x01,  //  Unit (SILinear: cm⁻² * cd)         21
    # 0x55, 0x0e,                    //  Unit Exponent (-2)                 26
    # 0x75, 0x20,                    //  Report Size (32)                   28
    # 0x95, 0x01,                    //  Report Count (1)                   30
    # 0xb1, 0x42,                    //  Feature (Data,Var,Abs,Null)        32

    # 0x05, 0x0f,                    //  Usage Page (Vendor Usage Page 0x0f) 34
    # 0x09, 0x50,                    //  Usage (Vendor Usage 0x50)          36
    # 0x15, 0x00,                    //  Logical Minimum (0)                38
    # 0x26, 0x20, 0x4e,              //  Logical Maximum (20000)            40
    # 0x66, 0x10, 0x01,              //  Unit (None)                        43
    # 0x55, 0x0d,                    //  Unit Exponent (-3)                 46
    # 0x75, 0x10,                    //  Report Size (16)                   48
    # 0xb1, 0x42,                    //  Feature (Data,Var,Abs,Null)        50

    # 0x06, 0x82, 0x00,              //  Usage Page (VESA Virtual Controls) 52
    # 0x09, 0x10,                    //  Usage (Brightness)                 55
    # 0x16, 0x90, 0x01,              //  Logical Minimum (400)              57
    # 0x27, 0x60, 0xea, 0x00, 0x00,  //  Logical Maximum (60000)            60
    # 0x67, 0xe1, 0x00, 0x00, 0x01,  //  Unit (SILinear: cm⁻² * cd)         65
    # 0x55, 0x0e,                    //  Unit Exponent (-2)                 70
    # 0x75, 0x20,                    //  Report Size (32)                   72
    # 0x95, 0x01,                    //  Report Count (1)                   74
    # 0x81, 0x02,                    //  Input (Data,Var,Abs)               76

    # 0xc0,                          // End Collection                      78

    R: 79 05 80 09 01 a1 01 85 01 06 82 00 09 10 16 90 01 27 60 ea 00 00 67 e1 00 00 01 55 0e 75 20 95 01 b1 42 05 0f 09 50 15 00 26 20 4e 66 10 01 55 0d 75 10 b1 42 06 82 00 09 10 16 90 01 27 60 ea 00 00 67 e1 00 00 01 55 0e 75 20 95 01 81 02 c0
    N: device 0:0
    I: 3 0001 0001

Related projects
----------------
Other projects that helped along the way were `LG-ultrafine-brightness`_ and
acdcontrol_.

.. _acdcontrol: https://github.com/yhaenggi/acdcontrol
.. _LG-ultrafine-brightness: https://github.com/ycsos/LG-ultrafine-brightness