Low level monitor API

Question

Low level monitor API

Rick Fang 1

Hi,
I can control the brightness value of my HDMI monitor using SetVCPFeature API as below link.
https://learn.microsoft.com/en-us/windows/win32/monitor/using-the-low-level-monitor-configuration-functions

I can get my monitor handle, and then I just write VCP code 0x10 to second parameter, 50 (brightness value) to third parameter. The brightness value of HDMI monitor can be controlled well.
Example sample code : SetVCPFeature(hMonitor, 0x10, 50);

We design monitor product. We can design the firmware inside the monitor product. My customer demands to create their customization DDC/CI protocol instead of using general VCP code.
Example protocol of adjusting LCD brightness : 07 00 4D 43 43 02 23 81 3F 3F

I need to write a test program to send these communication bytes over the HDMI or DP port. Next, firmware engineer can design the protocol function in the firmware of monitor.
However SetVCPFeature support VCP code only. I cannot put additional byte on it.
Does any monitor API able to support this usage ?

thanks
Rick

Drake Wu - MSFT 996 Reputation points

2020-12-25T01:54:27.147+00:00

Hi, @Rick Fang

My customer demands to create their customization DDC/CI protocol instead of using general VCP code.

If you want to change the display brightness, maybe you can try SetMonitorBrightness. AFAIK, there is no other function to send commands directly. Unless you use DeviceIoControl to communicate with the driver. For this problem, you can ask on Windows Hardware WDK and Driver Development forum to get more professional support.
Rick Fang 1 Reputation point

2020-12-26T07:42:14.643+00:00

Hi,
Does .NET framework library support this low level data protocol on DDC/CI ?
I can change to use C#.

Rick
Pavel A 431 Reputation points

2020-12-27T02:57:46.9+00:00

@DrakeWu The WDK forum is already running down, the new location on Q&A is
https://learn.microsoft.com/en-us/answers/topics/windows-hardware-wdk-general.html

Full list of WDK and hardware related tags is on the Windows landing page, on the right side.

Another relevant tag is winapi-audio-video: https://learn.microsoft.com/en-us/answers/topics/winapi-audio-video.html
Drake Wu - MSFT 996 Reputation points

2020-12-28T01:13:26.447+00:00

@Pavel A Got it! Thanks for update.

Your answer

Drake Wu - MSFT 996 Reputation points

2020-12-25T01:54:27.147+00:00

Hi, @Rick Fang

My customer demands to create their customization DDC/CI protocol instead of using general VCP code.

If you want to change the display brightness, maybe you can try SetMonitorBrightness. AFAIK, there is no other function to send commands directly. Unless you use DeviceIoControl to communicate with the driver. For this problem, you can ask on Windows Hardware WDK and Driver Development forum to get more professional support.
Rick Fang 1 Reputation point

2020-12-26T07:42:14.643+00:00

Hi,
Does .NET framework library support this low level data protocol on DDC/CI ?
I can change to use C#.

Rick
Pavel A 431 Reputation points

2020-12-27T02:57:46.9+00:00

@DrakeWu The WDK forum is already running down, the new location on Q&A is
https://learn.microsoft.com/en-us/answers/topics/windows-hardware-wdk-general.html

Full list of WDK and hardware related tags is on the Windows landing page, on the right side.

Another relevant tag is winapi-audio-video: https://learn.microsoft.com/en-us/answers/topics/winapi-audio-video.html
Drake Wu - MSFT 996 Reputation points

2020-12-28T01:13:26.447+00:00

@Pavel A Got it! Thanks for update.

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Low level monitor API

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