This little tool controls external displays (connected via USB-C/DisplayPort Alt Mode) using DDC/CI on M1 Macs. Useful to embed in various scripts.
Please note that controlling a HDMI display via the 2020 M1 Mini's HDMI port is not working. You have to use DisplayPort over USB-C!
You need clang from Apple's Command Line Tools (installs automatically if not present).
After download, enter (in Terminal):
make
You can then run the app by entering:
./m1ddc
m1ddc set contrast 5 - Sets contrast to 5 on default display
m1ddc get luminance - Returns current luminance ("brightness") on default display
m1ddc set red 90 - Sets red gain to 90
m1ddc chg volume -10 - Decreases volume by 10 on default display
m1ddc display list - Lists displays
m1ddc display 1 set volume 50 - Sets volume to 50 on Display 1
set luminance n - Sets luminance ("brightness") to n, where n is a number between 0 and the maximum value (usually 100).
set contrast n - Sets contrast to n, where n is a number between 0 and the maximum value (usually 100).
set (red,green,blue) n - Sets selected color channel gain to n, where n is a number between 0 and the maximum value (usually 100).
set volume n - Sets volume to n, where n is a number between 0 and the maximum value (usually 100).
set input n - Sets input source to n, common values include:
DisplayPort 1: 15, DisplayPort 2: 16, HDMI 1: 17 HDMI 2: 18, USB-C: 27.
set mute on - Sets mute on (you can use 1 instead of 'on')
set mute off - Sets mute off (you can use 2 instead of 'off')
get luminance - Returns current luminance (if supported by the display).
get contrast - Returns current contrast (if supported by the display).
get (red,green,blue) - Returns current color gain (if supported by the display).
get volume - Returns current volume (if supported by the display).
max luminance - Returns maximum luminance (if supported by the display, usually 100).
max contrast - Returns maximum contrast (if supported by the display, usually 100).
max (red,green,blue) - Returns maximum color gain (if supported by the display, usually 100).
max volume - Returns maximum volume (if supported by the display, usually 100).
chg luminance n - Changes luminance by n and returns the current value (requires current and max reading support).
chg contrast n - Changes contrast by n and returns the current value (requires current and max reading support).
chg (red,green,blue) n - Changes color gain by n and returns the current value (requires current and max reading support).
chg volume n - Changes volume by n and returns the current value (requires current and max reading support).
display list - Lists displays.
display n - Chooses which display to control (use number 1, 2 etc.)
You can also use 'l', 'v' instead of 'luminance', 'volume' etc.
Check out the following hammerspoon script.
This script allows you to control the volume of your external Display' brightness, contrast and volume via DDC (if you use an M1 Mac) using m1ddc and also control your Yamaha AV Receiver through network. The script listens to the standard Apple keyboard media keys and shos the standard macOS Birghtness and Volume OSDs via uses showosd :
https://gist.github.com/waydabber/3241fc146cef65131a42ce30e4b6eab7
If you like m1ddc, you'll like MonitorControl even better! If you need a complete Swift implementation for DDC control on Apple Silicon macs, you can take a look at arm64DDC which is a complete self contained library I made for MonitorControl.
Thanks to @tao-j @alin23, @ybbond
Enjoy!