Replace Windows USB Class Driver with a custom driver?

Question

I wonder if anyone can help at all, a bit of a specialist problem this.

I have an application that needs to read and analyse a number of USB devices (not simultaneously, they are each run in seperate tests and could in theory be run on different machines).

Each of the USB devices is based on the USB HID class, and are manufactured by different companies, none of these USB devices are designed to be run on PC, but are meant for a different platform, however for the purposes of testing the devices the client has requested that the test application is run from a PC.

Some of the devices will start up, be recognised by windows which will initialise and start them correctly using the generic HID class driver built into windows, the devices will then start sending correct data packets of the data to be tested.

Some of the devices will start up, be recognised by windows which will try to start them but fail to fully to initialise them leaving them in a half initialised state. This is fine, as I can use my beagle protocol analyser to capture the initialisation packets from the genuine platform and then use the LibUSBDotNet library to replicate the remaining packets in the initialisation sequence and get them to start sending the packets correctly.

The problem I have is with one particular device (though there are some more I haven't tested yet so it's quite possible one of those may also exhibit the same problem). The issue is the the Windows HID class driver recognises the device and trys to initialise and start it, this works after a fashion and the device starts sending data.

The problem is that the data being sent is different to that which is sent to the genuine platform (containing only a subset of the full data). It's as though windows has initialised the device into a different mode.

When I capture the initialisation packets from both the PC and the genuine platform using my USB protocol analyser I see that Windows is sending some slightly different initialisation packets. Using LibUSBDotNet to resend the correct packets once Windows has already started the device seems to have no effect.

My problem is that I need to stop windows from trying to initialise the device using the standard HID class driver, I've tried removing the driver in Device Manager but it still initialises it (and the driver is magically reassigned in device manager). I've done some investigation and there are possible alternatives:

1. Create a specific driver which windows will assign to the particular VID/PID of the device but that does nothing, then I can use LibUSBDotNet to send the correct initialisation sequence to the device from within my own code.

2. Use something like WinUSB to create a proper driver for the device (or possibly to create a "dead" driver like 1.

Will a driver with a specific VID/PID defined be used by windows in preference to it's inbuilt USB HID class driver? If not then I would be wasting my time going down this route?

Note, my mac initialises the problem device correctly, and I've asked the question of the client whether the application can be developed for Mac and their answer was frustrating Windows only.

I've no experience in writing proper Windows drivers, though I have experience in talking to USB at a relatively low level (so that part doesn't worry too much). Can anyone suggest a good course of action (before I potentially waste weeks investigating how to write drivers for the PC only to find my selected course of action can't deliver what I required).

Any help or suggest much appreciated.

Thanks, Rich

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Added after trying suggestions below:

I tried using the LibUsbDotNet inf wizard to create the necessary files and install them and this appeared to work - certainly the device was now appearing in Device Manager as a libusb-win32 device - not HID device and the associated driver was libusb driver. Even after doing this the device still seems to become initialised and start sending the wrong type of data packets although now those packets are no longer handled by the class driver and are just lost.

I also came across Zadig which has a similar inf creation wizard for WinUSB and this had exactly the same result.

A colleague has suggested that it might not be windows itself that is switching the device into this mode, rather the device identifying that it is connected to a windows machine and switching itself into this mode. I suspect this is the case, in which case I am stuck - time to have another conversation with the client.

Many thanks for the help.

Answer 1

You're using libusb-win32 as a filter driver; that is, the HidUsb device driver is assigned and loaded for your device, but then the libusb-win32 driver is loaded on top and gives you unobstructed access to the hardware.

If you don't want a HidUsb (or any other class driver) to perform any communication "on your behalf", simply associate libusb-win32 as a device driver with your hardware. For this, you'd have to create an .INF file associating it with the VID/PID/Revision of each USB device. If I recall correctly, libusb-win32 even comes with a utility to generate such .INF files.

If you install this .INF file e.g. with PnpUtil.exe (available on Vista or higher), you might still run into issues where, although you're a better match than the generic HID driver, the HID driver is still selected.

The generic HID driver matches devices by their Compatible IDs (i.e. by a USB interface class) while you'd be matching by Hardware IDs (which have higher priority). However, Windows might give priority to other aspects, such as your driver being unsigned. Read: How Windows Selects Drivers

Luckily, even in that scenario, signing drivers with a self-generated certificate (use CertUtil.exe, MakeCat.exe and SignTool.exe) is not too difficult.