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Comment by redisman | Hacker News Reader

It's insane how monitor software hasn't developed an inch from the 90s. How hard can it be to have an open API for the basic controls at least so the OS can adjust them? Everything about my monitor is great - 144hz refresh rate, great viewing angle and colors - except if I want to change any of the physical properties (brightness, contrast) I'm clicking around on a variety of buttons that I can't see like I'm trying to set the clock on my VCR.

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This actually exists, and it’s called DDC/CI: https://en.m.wikipedia.org/wiki/Display_Data_Channel

I only recently learned about it myself while setting up a new monitor and asking myself wtf is this DDC/CI setting in the menu.

Thanks for the hot tip! I've been struggling with my monitor's menu buttons, but after reading your comment I found the macOS tool MonitorControl, which works perfectly.

I can control laptop brightness with `/sys/class/backlight/foo`, and my asus external monitor advertises capabilities over hdmi with `modprobe i2c-dev` and then `ddcutil capabilities`. Apparently this is governed by something called MCCS. You can find more info on the arch wiki.

I have a script with ddccontrol to change brightness of my external monitor:

    ddccontrol -r 0x10 -w ${NUM}0  dev:/dev/i2c-${DEV_NUM}

The internal:

    BACKLIGHT_PATH="/sys/class/backlight/intel_backlight/brightness"
    sh -c "echo ${NUM} > $BACKLIGHT_PATH"

The numbers are a slightly different scale, so I adjust them in the script.

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