USB Function Composite Device Drivers (Compact 7)
3/12/2014
Normally, a universal serial bus (USB) device can only perform one function at a time. To allow a USB device to perform multiple functions simultaneously, you use the USB function composite device driver available in Windows Embedded Compact. The USB function composite device driver acts as an intermediary between the USB Function Controller Drivers and one or more USB Function Client Drivers. For example, the USB function composite device driver allows the use of the USB Remote Network Driver Interface Specification (RNDIS) protocol and USB Function Mass Storage Client Drivers at the same time, enabling a USB hard disk to be accessed over a network connection.
Note
In order to use the USB function composite device driver in your OS the USB hardware must support multiple endpoints.
For more information about USB function drivers, see the following topics.
- USB Function Client Drivers
Enable a USB device to communicate with a USB host controller.
- USB Function Controller Drivers
Offer functions for I/O control codes (IOCTLs), model device drivers (MDDs), and platform-dependent drivers (PDDs).
- USB Function Mass Storage Client Drivers
Expose a storage device, such as a hard disk drive or mass storage device, to a USB host controller.
- USB Function Serial Client Drivers
Expose a stream interface to serial hardware, such as a serial modem.
To add this feature to your OS, see USB Function Driver Catalog Items and Sysgen Variables.
For reference information, see USB Function Controller MDD Functions and USB Function Client Driver Functions.
Note
SYSGEN_USBFN_COMPOSITE is required to build the USB Function Composite device driver. Unless the flag is present, it will not be possible to run multiple concurrent USB Function client drivers and no change in driver behavior will be evident.
Note
The USB Function Composite device driver will pass all power management IOCTL calls to the parent bus driver.