Introduction to WinUSB for Developers

Why WinUSB Matters for Driver Developers

As a driver developer, understanding WinUSB (Windows USB) can significantly streamline your development process, especially when working with USB devices. WinUSB is a generic driver included with Windows that allows you to communicate with USB devices without the need to write a custom driver. This can save you time, reduce complexity, and ensure compatibility across different Windows versions.

Key Benefits of Using WinUSB

1. Simplified Development:

   • Ease of Use: WinUSB abstracts much of the complexity involved in USB communication, making it easier for you to interact with USB devices.
   • No Custom Driver Needed: For many USB devices, WinUSB can be used directly, eliminating the need to write and maintain a custom driver.

2. Cross-Platform Compatibility:

   • Standardized Interface: WinUSB provides a standardized interface for USB communication, which can be beneficial for ensuring compatibility across different Windows versions.

3. Time and Cost Efficiency:

   • Reduced Development Time: Using WinUSB can significantly reduce the time required to develop and test a USB driver.
   • Lower Maintenance Costs: Since WinUSB is maintained by Microsoft, you can rely on it being updated and supported, reducing long-term maintenance costs.

4. Access to USB Features:

   • Full USB Functionality: WinUSB supports a wide range of USB features, including bulk transfers, control transfers, interrupt transfers, and isochronous transfers.

What You Can Accomplish with WinUSB

1. Device Communication:

   • Data Transfer: Send and receive data to and from a USB device using bulk, control, interrupt, or isochronous transfers.
   • Control Requests: Send control requests to configure the device or retrieve information.

2. Device Configuration:

   • Setting Configuration: Configure the USB device by selecting configurations, interfaces, and alternate settings.
   • Endpoint Management: Manage endpoints for data transfer.

3. Device Enumeration:

   • Device Identification: Enumerate and identify USB devices connected to the system.
   • Descriptor Retrieval: Retrieve device descriptors, configuration descriptors, interface descriptors, and endpoint descriptors.

4. Custom Applications:

   • User-Mode Applications: Develop user-mode applications that communicate with USB devices using the WinUSB API.
   • Firmware Updates: Implement firmware update mechanisms for USB devices.

5. Testing and Debugging:

   • Prototyping: Quickly prototype USB device communication to test hardware functionality.
   • Debugging: Use WinUSB to debug communication issues between the host and the USB device.

Components of WinUSB

WinUSB includes:

• A kernel-mode driver (Winusb.sys)
• A user-mode dynamic link library (Winusb.dll) that exposes WinUSB functions described in winusb.h. You can use these functions to manage USB devices with user-mode software.

By default, Winusb.sys is installed in the device's kernel-mode stack as an upper filter driver. Apps communicate with the device's UMDF function driver to issue read, write, or device I/O control requests. In this configuration, Winusb.sys serves as the device stack's Plug and Play and power owner. You can also install Winusb.sys as the function driver for a USB device.

Getting Started with WinUSB

This section includes information on:

• Selecting the correct driver for a device
• Using WinUSB to communicate with USB devices
• Installing Winusb.sys as the function driver for a USB device

You will also find detailed code examples that show how apps and USB devices communicate.

Related Topics

• Microsoft-provided USB drivers