USB firmware programming

hectorhg wrote:
> 
> I've read a little more about composite devices, do you mean that
> just adding a new interface to my CDC device with mass storage
> class should be enough?? will the PC detect it? Is it not
> necessary a special device descriptor to represent that, or a
> protocol, subclass or whatever??

Please do not top-post.  Your answer belongs after (or intermixed
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irrelevant material.  See the following links:

  <http://www.catb.org/~esr/faqs/smart-questions.html>
  <http://www.caliburn.nl/topposting.html>
  <http://www.netmeister.org/news/learn2quote.html>
  <http://cfaj.freeshell.org/google/>  (taming google)

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** Posted from http://www.teranews.com **

>Your device descriptor would need to look something like:
>
>	Device class	0
>	Device subclass 0
>	Device protocol	0
>
>
>Then you'd have three interface descriptors:
>
>(CDC Abstract Control)
>	Interface class		0x02
>	Interface subclass	0x02
>	Interface protocol	0xff
>(CDC Data)
>	Interface class		0x0a
>	Interface subclass	0x00
>	Intterface protocol	0x00
>(MSC - not values depend on your implementation)
>	Interface class		0x08
>	Interface subclass	0x06
>	Interface protocol	0x50
>

That should work, but on xp at least it doesn't. I've tried everything I
can think of, and it seems that if the DeviceClass is not 0x02 then the
RNDIS driver will fail to start.

If you change the DeviceClass to 0x02 then RNDIS starts but windows
doesn't try to load the mass storage driver.

If you then move your ms interface descriptor to be first, then mass
storage works but windows doesn't try to load the RNDIS driver.

So it seems that on XP your choice is RNDIS or mass storage, but not both.
I'd sure like to find a way to get around that (without writing a custom
driver).