Re: [ECOS] USB MSD stack

[Frank Pagliughi <fpagliughi@mindspring.com>]

Doyle, Patrick wrote:

>>From: Andrew Lunn [mailto:andrew@lunn.ch] 
>>
>>What you might be able to do is not set a device class. You then need
>>to tell M$ windows that when it sees vendor XYZ it should load both
>>the HID driver and the MSD driver. The HID driver will grab the
>>interupt end point and the MSD driver will grab the bulk in and out
>>endpoints.  A lot will depend on what level M$ does its resource
>>allocations. If it does the allocation at interface level, it will not
>>work, the first loaded driver will win. If it does it at endpoint
>>level you have a chance. Handling control transfers is going to be
>>interesting.
>>
>>Or you could just write a HID and MSD driver for M$. Well, you don't
>>need full drivers, just an intermediate driver which has two
>>interfaces on top and one on the bottom. Does M$ have USB intermediate
>>drivers? I know they exist for the networking stack....
>>
>>         Andrew
>>    
>>
>
>Hmmm... we are hoping to avoid writing any host drivers (or even .ini files,
>if possible).  But we may learn that that is not possible.
>
>Thanks again for your thoughts...
>
>--wpd
>
>  
>
If you can get away without writing a Windows driver, I reccomend it. 
It's at least one less variable when debugging. You may need or want to 
write your own INF file if you've got multiple interfaces.

On most device chips I've seen, interrupt transfers work in a similar 
manner to bulk transfers. It's up to the host to guarantee bandwidth to 
the interrupt transfers and deal with the complexities. So it should be 
no problem doing the device side of the HID in eCos.

For USB questions, the discussion board on usb.org is excelent. The 
person who wrote your USB book may be the one to answer your question. 
The discussion board is at:
    http://www.usb.org/phpbb/

Frank


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