USB without a driver (WinUSB)

Description:

With USB_WCID defined, the USB library answers the Microsoft OS 1.0 descriptor requests that Windows sends to a new device. Windows 8.1 and later then load their own WinUSB driver for the device when it is first plugged in: there is no driver to install, no installer to run and no reboot.

The program is unchanged otherwise: it uses the same vendor requests (USB_SETUP_HANDLER, USBBufferWrite), and a PC program using LibUsbDotNet, libusb or WinUSB opens the device by its vendor ID and product ID, or by its device interface GUID.

Enabling Constants:

Constant Controls Default

USB_WCID

Define it to answer the Microsoft OS 1.0 descriptor requests (the OS string, the Extended Compat ID "WINUSB" and the Extended Properties).

Not defined

USB_WCID_GUID

The device interface GUID, as a string of 38 characters in the form "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}". Required with USB_WCID: the compiler stops with an error when it is missing. Give each solution a GUID of its own.

None

USB_WCID_VENDOR_CODE

The request code Windows uses to read the descriptors. It must not be one of the program’s own request codes.

0x20

Example:

    #chip 18F14K50, 48

    #define USB_VID 0x04D8
    #define USB_PID 0x0052
    #define USB_REV 0x0100

    'WinUSB without a driver
    #define USB_WCID
    #define USB_WCID_GUID "{BFC2B144-FB5A-4F56-98AC-93BC164EED46}"

    #define USB_PRODUCT_NAME "GCBASIC WinUSB " + CHIPNAMESTR
    #define USB_SETUP_HANDLER SetupHandler_CallBack

    #include <usb.h>

Notes:

  • Windows asks a device for its Microsoft OS descriptors only once for each vendor ID, product ID and USB_REV (bcdDevice), and remembers the answer. A device first plugged in without USB_WCID is not asked again until USB_REV changes, or until its key under HKLM\SYSTEM\CurrentControlSet\Control\usbflags\ (vendor ID, product ID and revision as twelve hexadecimal digits) is deleted.
  • The vendor ID and product ID are not those of the LibK driver above (0x1209 / 0x2006): a PC with that driver installed would use it for the device instead of WinUSB.
  • LibUsbDotNet reads the revision from the device’s hardware ID as a decimal number: for USB_REV 0x0100, search for revision 100.
  • Windows 7 does not read these descriptors: it still needs a driver.

Tested on (but not limited to)

    PIC18F14K50, PIC16F1454, PIC16F1455, PIC16F1459, PIC18F46J50 (PIC18F Starter Kit 1)
    Windows 11 x64

See Also:

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