Skip to content

Windows Backend

Jump to bottom Edit New page
pbatard edited this page Jul 5, 2012 · 1 revision

IMPORTANT: NEC/Renesas USB 3.0 users, please upgrade your drivers to version 2.1.16.0 or later. Older versions of the driver have a bug that prevents libusbx from accessing devices.

Table of Contents

Overview

About

This project adds Windows platform support to the libusbx Open Source library, in order to help developers easily communicate with USB devices on Windows. Currently it supports the WinUSB and HID drivers for generic USB device access (with a restriction for HID keyboards and mice, as only the system can access them). libusb0.sys and libusbK.sys driver support will also be added soon.

Current Status

The Windows backend is part of the libusbx 1.0.9 official release. While it has been tested for a couple of years and is assumed stable, because libusbx v1.0.9 marks its first official release, it should be considered EXPERIMENTAL over the next few releases.

Binary Snapshots

Pre-built binary snapshots are provided in the release directory under /<current-version>/Windows/.
These 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.

Supported Environments

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

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

USB 3.0 Support

libusbx supports USB 3.0 controllers and devices on Windows. 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 still be considered experimental.

Also, if you are using a NEC/Renesas USB 3.0 controller, such as the fairly widespread uPD720200/uPD720200A, 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 libusbx.

Windows 8.0 Support

libusbx has been tested under the various Windows 8 Previews (Developer, Consumer, Release) for both 32 and 64 bit and no issues were found.

.NET support

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

How to use libusbx on Windows

Driver Installation

To access your USB devices with the Windows backend, if not using HID, you will need to install the WinUSB driver. Two options are available:

  • The easiest option is to use the most recent version of the Automated Driver Installer GUI application Zadig.exe.
    • Note: Zadig also allows the selection and installation of the latest libusb-win32 and libusbK drivers.
  • Or you can download the WinUSB driver files, then customize the inf file for your device.

Development Considerations

The handling of composite devices under Windows is done with multiple drivers, descendants of the usbccgp.sys driver (Composite Generic Parent), as this is the default for the OS. 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 libusbx file descriptors with poll() on cygwin is NOT supported. In a future version of libusbx, we should provide better handling of native Windows events, but this requires a redesign of the libusbx API, so is unlikely to occur before libusbx 2.0.

Known Restrictions

  • WinUSB cannot be used to send an actual reset command to an USB device.
  • WinUSB cannot be used to set a device configuration that is different from the first one.
  • WinUSB does not support multiple concurrent applications (as per the MSDN documentation).
  • 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.

Development Information

To Do

  • libusb0.sys & libusbk.sys driver support
  • hotplug detection

Links

Add a custom footer
Add a custom sidebar
Clone this wiki locally