This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(316.8, 14.000000000000002%, 40%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAA%3C/text%3E%3C/svg%3E)
Hello,
I'm not sure this is the right place to ask, I beg a mod to move this post if not.
Some Benq monitors come with a device you have to connect straight to the monitor (mini-usb type B) for quickly switching among some monitor presets.
I want to find an alternative use for this device, I want to connect it to a pc and use it as an input device (keyboard shortcuts).
Where should I start to read up on how to write such a driver (for windows 10, of course)?
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(144, 84%, 23%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ECK%3C/text%3E%3C/svg%3E)
There are different ways to start out here, here are some options that could be explored.
https://learn.microsoft.com/en-us/windows-hardware/drivers/samples/input-driver-samples
https://learn.microsoft.com/en-us/windows-hardware/drivers/develop/building-a-driver
https://learn.microsoft.com/en-us/windows-hardware/drivers/gettingstarted/writing-your-first-driver
Browsing around I found this https://stackoverflow.com/questions/3527707/writing-a-keyboard-device-driver
in which a user says I may need the specification of the hardware interface. I didn't expect that, is that a thing I really need?
There is no way Benq support would provide me with it...
To start with.... when you connect it to a PC, is it visible in Device Manager or USBView? If not, game over.
Else, does it look like a HID or other known class?
--pa
Yep I can see it in Device Manager. It looks like this
The Device Descriptor Request Failed error is a pretty clear sign that a PC cannot use the device. But imagining it does enumerate properly, you would need to know how to communicate with the device (maybe HID, maybe custom)
what do you mean by "a PC cannot use the device" exactly? Do you mean straightaway? If so, well I knew it, that is why I'm here :).
Do you have any advice on how to approach the problem? Do I really need the hardware specification from Benq?
For the PC to use the device, it must provide a device descriptor. Since the device is failing this request, the PC cannot successfully enumerate the device and cannot get to the state where it can potentially load a driver for it. You need some basic understanding of a) how USB works and b) how this device works to accomplish your task. The device descriptor failure falls into bucket a).
thanks.
Are you implying since the PC cannot enumerate the device there is nothing I can do?
If not, I have 3 questions:
Benq apparently does not want users to connect this thing to anything besides their display.
But from hardware POV it may be a real USB device.
To use it as a Windows input device, you will need the following:
Decide whether it's worth the effort.
--pa
Getting the device to enumerate isn't really a computer science problem, it is a hardware problem. There is no way to tell the OS (more specifically the USB host controller driver) to fake it out and ignore this error. The device descriptor is fundamental to a functioning usb device. Do you need more information form Beng? ... that depends on what protocol the device uses. If it is a USB spec defined protocol, there is a windows driver for it and you can use an existing Win32 API to communicate with the device. If it is not spec compliant, you can use winusb for raw communication and either reverse engineer the device or have Benq provide a spec sheet.
by saying I'm a computer scientist I wanted to imply I'm clueless about all this but not 100% clueless (about 99% I would say :) )
Thanks for all the explanation, but I'm still not clear about the most important thing, because you said "there is no way for the OS to ignore/fix the error", but then you kept explaining steps that would be subsequent to that first one.
Is there a way I can "fix" the error about the device descriptor or is it simply/virtually impossible?
There is no amount of external "fixing"" you can apply to have the device enumerate properly. My statements about next steps are trying to answer your other questions of how hard would it be to interact with the device (based on the assumption it enumerated properly). IOW, we don't know how hard it would to interact with the device because it is not getting far enough in the USB enumeration protocol to have enough data as to how the device describes itself...I was just trying to be thorough and address all your questions.
All right, thanks a lot. That's very disappointing...