wiki:windows_backend
Last modified 15 months ago Last modified on 09/03/13 20:01:58

Windows backend

The author of most of the Windows backend doesn't contribute to libusb anymore, but all meaningful changes in the libusbx fork, which he leads, are continuously included into libusb.

About

This project adds Windows platform support to the libusb-1.0 Open Source library, in order to help developers easily communicate with USB devices on Windows.
Currently it supports the WinUSB driver for generic USB device access, with more drivers to be added later.

Status

With 1.0.9 release, the Windows backend should be considered as getting from experimental to stable.

Supported systems are all Windows platforms, starting with Windows XP, and including 64 bit versions, with the following exceptions:

  • Windows 2003 (Microsoft does not officially support WinUSB on 32bit/64bit Windows 2003)
  • Windows XP 64 bit (Microsoft does not officially support WinUSB on 64bit Windows XP)

Supported development environments

The following development environments are currently supported for libusb 1.0 on Windows:

  • MinGW (32 bit) or MinGW-w64. You can easily install MinGW (32 bit) using mingw-get. For a precompiled MinGW-w64 distribution, you can also check TDM64. Cross-building libusb-1.0 Windows backend under Linux or other OS using MinGW and MinGW-w64 is also fully supported.
  • Microsoft Visual C++ (Visual Studio), either Express or full version, starting with version 6.0. You should be able to produce both win32 and x64 binaries using Visual C++. Take note that the Express version of Visual C++ can not produce 64bit binaries by default and will require you to install the Windows SDK to do so.
  • Windows DDK build environment, which is freely available, through the use of the 'ddk_build.cmd' file. This will also produce both 32 and 64 bits binaries.
  • Cygwin. Cygwin currently can not produce 64bit binaries.

Source

The current development Windows backend is available in the libusb main git repository.

For those not familiar with git, here are the git commands you can use retrieve and compile the Windows branch:

git clone git://git.libusb.org/libusb.git ; retrieve development branch (this only needs to be done once)
cd libusb
git pull                                          ; keep in sync with the remote tree

On Windows, if you don't want to use git on the commandline, you can use TortoiseGit to access and keep in sync with the git repository.
Note that before you can install TortoiseGit you need to install MSysGit.

Also note that, for MinGW and cygwin, as with the original libusb 1.0 development tree, you should to run ./autogen.sh in order to have configure and Makefile created for you.

Creating applications using libusb

To create projects relying on libusb 1.0, please refer to how the example executables (lsusb, xusb) are compiled.
If you use a the release version 1.0.9 or later, no additional libraries should be needed besides libusb.

USB 3.0 support

libusb 1.0 supports USB 3.0 controllers and devices on Windows, from 1.0.9 release onwards. Because of the large number of USB 3.0 controllers, the lack of official USB 3.0 support from Microsoft in Windows 7 and earlier as well as limited testing, be mindful that USB 3.0 support should be considered experimental. Also, if you are using a NEC/Renesas USB 3.0 controller, such as the fairly widespread uPD720200/uPD720200A, you please make sure that your controller drivers are version 2.1.16.0 or later. Older versions of the drivers have a bug that prevents access to USB devices when using libusb.

Windows 8.0 support

libusb 1.0 has been tested under Windows 8 Developer preview and Consumer Preview (both 32 and 64 bit) and any recent version is expected to work there.

.NET support

A .NET version of libusb, called LibUsbDotNet, based on libusb 1.0 and the Windows backend has also been developed by Travis Robinson.
If you plan to use libusb in a .NET project, make sure you check http://libusbdotnet.sourceforge.net or http://sourceforge.net/projects/libusbdotnet/

Driver Installation

To access your USB devices with the Windows backend you need to install the relevant driver. Two options are available:

  • The easiest option is to use the most recent version of the Automated Driver Installer GUI application Zadig.exe, which is part of libwdi, the Windows Driver Installer library.
    The current version, which is compatible with both 32 and 64 bit Windows platforms starting with Windows XP, can install a WinUSB driver for any USB device.
    The installer needs to run with administrative privileges, so you are strongly encouraged to use a version that has been digitally signed, such as any official version from v2.0.0.151. You can also recompile your own version from the source.
  • Or you can download the WinUSB driver files, then customize the .inf for your device and install the driver by following the instructions that are either provided here or in the README file that comes with the driver archive.

Latest Binary Snapshots

The following pre-built binary snapshots are provided AS IS for your convenience, generated for the following environments:

  • Microsoft Visual Studio and DDK/WDK -> MS32(32 bit) and MS64 (64 bit) directories
  • MinGW -> MinGW32 (32 bit) and MinGW64 (64 bit) directories

Note that these archives are provided in the 7z format so you may have to install 7-zip.

  • You can find newer release binary as part of libusbx releases

Development Considerations

  • If you want to access devices outside of WinUSB WinUSB, such as HID ones, you can use the HID branch, which is maintained separately due to an executive decision by the libusb maintainer to remove HID support for Windows. Or you can use another library such as HIDAPI.
  • Windows' handling of composite devices is done with multiple drivers (VID_####&PID_####&MI_##), descendants of the usbccgp.sys driver (Composite Generic Parent), as this is Windows' default. For more info, see "2. How Windows handles a composite device" at http://www.cygnal.org/ubb/Forum9/HTML/001050.html. It is however possible to replace the composite parent driver with WinUSB to access the device.
  • Because Windows does not provide a native poll() function, and cygwin is the only development environment that provides such a call, the use of libusb file descriptors with poll() on cygwin is NOT supported. In a future version of libusb, we will try to provide better handling of native Windows events, but this will require a redesign of the libusb API, so is unlikely to occur before libusb 2.0.

Known Restrictions

  • WinUSB cannot be used to send an actual reset command to an USB device. This is a limitation of the Microsoft driver.
  • WinUSB cannot be used to set a device configuration that is different from the default one. This is a limitation of the Microsoft driver.
  • WinUSB does not support multiple concurrent applications (as per the MSDN documenation).
  • WinUSB does not support isochronous transfers.
  • Because there is no native poll on Windows, the ability to return externally pollable file descriptors on Windows (libusb_get_pollfd) returns an error.

To Do

  • hotplug detection

Development's status log

Please consult the git log.
NB: Previous development occurred on the Google Code SVN Repository but this is no longer maintained.

Mailing list and IRC

Please subscribe to the mailing list and/or join the IRC channel if you are using the library or interested in discussing further library development.

Attachments

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