


Each device class is identified by a USB-IF approved class, subclass, and protocol codes, all of which are provided by the IHV in device descriptors in the firmware. The USB-IF defines those classes and their specifications. USB device classes are categories of devices with similar characteristics and that perform common functions. More guidelines are included in Choosing a driver model for developing a USB client driver. If a Microsoft-provided driver isn't available for the USB device class to which your device belongs, then consider using generic drivers, Winusb.sys or Usbccgp.sys.

If you are writing a custom driver: Before writing a driver for your USB device, determine whether a Microsoft-provided driver meets the device requirements. The drivers are updated through Windows Update. They're available in the \Windows\System32\DriverStore\FileRepository folder. These drivers and their installation files are included in Windows. If you are installing USB drivers: You don't need to download USB device class drivers.
