STM32_USB-Host-Device_Lib - host bulk transfer

[turboscrew]

Posted on January 17, 2014 at 15:30

I looked into MSC host example, but I thing BOT is not ordinary bulk transfer?

I'm still thinking about RNDIS - the data transfer.

Is that also wrapped-command-status transfer or just plain data exchange via bulk-EPs?

If no wrappers are needed, how is it done using the library mentioned in the title?

Even if RNDIS data was wrapped-command-status transfer, I'd still like to also know how the non-wrapped transfer works.

[edit]

Or is it so, that (maybe some weird special cases excluded) bulk transfers always use wrapped command and status control transfers as a part of the ''protocol''?

[turboscrew]

Posted on January 18, 2014 at 12:24

I tried to read the MSC BOT code, but didn't quite get it.

What I got from it was:

• BOT (bulk) transfer data can be quite big. Much bigger than USB frame (256 frames).
• For each BOT transfer the wrapped command and status transfer through control OUT EP is used for transmission setup
• After the setup several bulk frames (of a transfer) can be transmitted with that one setup.
• The lower level parts of the library handle the segmentation (and reassembly) of the data to bulk frames.

Or am I totally lost?

[turboscrew]

Posted on January 25, 2014 at 18:28

Bump.

[turboscrew]

Posted on January 28, 2014 at 21:08

Maybe I've been unclear?

The question is:

Is RNDIS data transferred as just a REMOTE_NDIS_PACKET_MSG sent as a data block via bulk EP, or is the header sent via the control EP and the actual data via bulk EP (as in BOT transfer) ?

My guess is: the first.