When I plug a USB web Camera into a PC via USB, what communications is used? I know each device COULD have its own uniques driver, but it seems as though 99% use a common built in driver now. Where is it spec'd and how do you get a linux embedded device to act like a webcam?
What you're looking for is the USB Video Class and you can download the specification for this and other standard USB device classes here:
http://www.usb.org/developers/docs/devclass_docs/
The Linux USB gadget framework has code to emulate such a device:
https://github.com/torvalds/linux/blob/master/drivers/usb/gadget/function/f_uvc.c
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I have an old SONY Minidisc player that has USB output for NetMD interfacing with a PC. I am searching for someone who can tell me how to use WebUSB on my Mac to access the files. The Mac does NOT recognize the device connected via USB.
I made a custom USB sensor device that runs on a Windows 8.1 / 10 desktop computer using the WinUSB driver (I implemented Microsoft extended USB descriptors in device firmware to automatically install the driver when the device connected).
Can I use a WinUSB device on HoloLens2? Or, if there is no WinUSB support on HoloLens2, how can I use my USB device with a “custom USB device class”?
At the moment, I do not have a hololens2, but I need to understand how the USB works on it.
Edit: I found this link: https://learn.microsoft.com/en-us/hololens/hololens-connect-devices#hololens-2-connect-usb-c-devices
It says that hololens2 supports the following device classes:
Mass storage devices (such as thumb drives)
Ethernet adapters (including ethernet plus charging)
USB-C-to-3.5mm digital audio adapters
USB-C digital audio headsets (including headset adapters plus charging)
Wired mouse
Wired keyboard
Combination PD hubs (USB A plus PD charging)
My device does not implement any of these classes (custom class). Is there a chance to make it work on hololens2?
I finally tested my code and USB device on real Hololens 2. The USB device works great there because Hololens2 supports WinUSB! The WinUSB driver was installed automatically (my device has WinUSB descriptors).
According to the documentation you referred, all classes HoloLens2 supports have been listed, and unlisted classes are not supported.
Could you provide more information about your business request and submit a feature request via feedback hub on new feature request to be considered in future releases of HoloLens OS and devices?
If it’s a hot impacted feature, it will be possible to be given priority to jump in the development schedule. Actually, the existing classed on HoloLens 2 are also based on user’s feedback in such way.
For how to post feedback request, you can follow this doc: Send feedback to Microsoft with the Feedback Hub app.
I use webcam-capture(java api) to get video stream from a usb camera, it work fine.
I want read a usb device descriptor(store some private information), i find out that should install WinUSB or libusbk as a driver to the usb devices. and it test ok, read the descriptor success (by libusb_control_transfer api)
the question is:
befor I install WinUSB, the usb camera is a camera device in the windows device management list. the LibUSB work fail, can't open the usb devices, the error number is -5, means entrypoin not find
after I install WinUSB, libUSB api work ok, but the webcam program can't open the usb devices, it is a universal usb device in the windows device management list.
is there some way the webcam work ok, at the same time, i can read the usb device descriptor use libusb or use other something?
i tested on windows 7 and windows 8, have the same problem.
thanks.
Sadly this is not possible because each of your applications needs a different driver. The only way this can work is if you use libusb and build you own capturing api on top which is quite complicated. As long as webcam-capture can not read the data you want to know about the webcam I am afraid this is not possible.
I have an Arduino-compatible board with USB Host Shield. It is connected to an Acer A100 Android tablet running "Ice Cream Sandwich" (Android 4.0.3) with Kernel 2.6.39.4. (The tablet has a USB micro connector and does not support USB HOST mode and therefore cannot connect directly to a USB accessory device.)
This picture shows what I have been able to do successfully (but with my tablet in place of the phone).
http://www.seeedstudio.com/wiki/File:SeeeduinoADK_Setup.jpg
I would like to find an example of using an Android tablet connected to a USB Accessory (such as a keyboard or flash drive) via Arduino.
Connecting the USB accessory to the Arduino's USB micro connector (using an external power supply) does not work.
Can anyone provide me with such an example?
Theoretically it should work, I haven't tried it yet though.
Arduino should act as the middle man and should relay signals both from your tablet and the accessory.
What code are you use?
This is: adk_release_20120606?
And what board are you use SeeeduinoADK?
I use board Seeeduino ADK, but unfortunately I could not make it work in USB accessory mode. My board work in only ADB (MicroBridge mode). See my work example
My tablet is Ainol Aurora with Android version 4.0.4 (CyanogenMod 9)
The rest of my team will make for my application a simple non-standard USB microphone, but until they finish it I will have to emulate it, for integration testing purposes.
Is there any risk in a physical loopback? Yes there is
Will a physical loopback work? Only with a USB bridge
There is any way to create a logical loopback? (MSDN has something about this)
There is any general purpose USB emulator software?
In case there is many options available I'd rather work it .NET/Matlab/Python solutions.
Edit: Proof of concept here
I strongly recommend this project, USB IP. It is a way of connecting USB devices over the network. There is a Windows client.
What this means is, you install the client on your Windows computer.
This device then expects to talk to a USB device connected to a Linux computer, the server:
What you now do, is either create a fake device driver for Linux, that looks like is connected to a physical USB device, but in reality is just logic pretending to be your USB device. There are tutorials for writing USB drivers for Linux. Or you create your own stub driver for the Device Control Manager (see picture above). This stub driver could run on Windows or Linux, it wouldn't matter. It could even run on the same Windows machine which is the USB client.
The DSF USB Loopback Device mentioned in the question itself, would be the same kind of solution as a stub driver for the Device Control Manager, but taking Linux out of the picture altogether.
You can write virtual USB device using QEMU.
You can duplicate already existing device, like the dev-serial.c found in this QEMU repository and change it for your needs.
After you write and compile your USB device you can simply attach it to your VM using the QEMU command line interface.