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Message
From: "Srikanth K S" <skashyap@t...>
Date: Tue, 24 Dec 2002 11:20:23 +0530
Subject: [usb] Zero length data packet?
Hello All,
I have some doubts on the sentences (bulleted) in sections 5.8.3 and
5.7.3 of USB 1.1 specification, quoted below:
"A bulk/interrupt transfer is complete when the endpoint does one of
the following:
Transfers a packet with a payload size less than wMaxPacketSize or
transfers a zero-length packet."
Well, I understand that it is the responsibility of HC to process its
TD given that the device transmits a short packet; In this case HC retires
its TD with or without error depending on its buffer rounding bit (and
host of other stuffs...)
The device has no iformation in it to decide that it has to send a
"zero lenght data packet"!!
When should device respond with "zero lenght data packet" during
a BULK / INTERRUPT IN transaction...?
With Best Regards,
--------------------------------------------------------------
Srikanth Kashyap S. | Tata
Elxsi Ltd.,
Sr. Engineer
| Whitefield Rd, Hoody,
SDG, ASIC / FPGA
| Bangalore 560 048
ph: 91-80-8410148 x 256/7 | mailto: skashyap@t...
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But I don't have to know an answer.I don't feel frightened by
not knowing things, by being lost in the mysterious universe
without having any purpose, which is the way it really is, as
far as I can tell, possibly. It doesn't frighten me.
-- Richard P. Feynman
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