Is it possible for a USB device to support multiple drivers? I'd like to support my own proprietary driver but also CCID as a second choice. When the device is plugged in, the user can select which one to use. The driver to use is determined by what the USB descriptor says, right? If that is so, is it possible to indicate that both drivers are supported? Is the idea of supporting two drivers doable?
A:
I am sure that it is not possible for a device to use two drivers at the same time but what is possible is for the device to enumerate using one class type and driver and then during its operation, in response to some command over the USB or operation of the device, for it to disconnect and then re-enumerate as a different type of device using the second driver.
As an example the product that I am developing normally enumerates as a CDC (serial port emulation) but when I need to reload the code it re-enumerates as a different device type and uses the chip vendor supplied driver to perform the code download. Once this completes then the device re-enumerates itself again as a CDC device type and resumes its serial port emulation.
You therefore need to provide a "command" interface that will trigger the transition between the two operating modes and to ensure that the two drivers are installed on the host computer ready for the mode switch.
Ian
2010-03-10 08:37:30
A:
On Windows, having two supported drivers is possible. In fact, to get Microsoft Logo certification, it is mandatory that the USB device supports this functionality. (Requirement CONNECT-0123)
However, the UI behavior you describe isn't offered by Microsoft. Driver selection is automatic.
Your USB device can indicate it supports two interfaces. In that case, both drivers will be loaded.
MSalters
2010-03-10 09:00:38