Author Topic: HUB fails to pass on ACK upstream?  (Read 9128 times)

beethoven

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HUB fails to pass on ACK upstream?
« on: March 20, 2012, 11:38:13 am »
Problem: Seem to me the 2.0 HUB passes data to a 1.1 USB device. The device ACKs, but the HUB fails to pass the ACK upstream.

Image of capture between HUB and HOST (both 2.0)


Image of capture between (2.0) HUB and (1.1) device


Note: index 44984 (1st image) no ACK follows..... index 158 (2nd image) ACK is sent by the device. At Index 160 (2nd image) the Device is confused about the new setup.txn transmissions.

Grateful for any help.

- Beethoven

[attachment deleted by admin]

Pat Crowe

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Re: HUB fails to pass on ACK upstream?
« Reply #1 on: March 20, 2012, 01:03:27 pm »
Looking at it quickly, I think it's a split interrupt completion. If so, this is normal behaviour. See Chapter 11.

beethoven

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Re: HUB fails to pass on ACK upstream?
« Reply #2 on: March 20, 2012, 02:25:53 pm »
Pat, Ah, I see what you mean in 11.18.6.1.  I had read that it was the 2.0 Device's 'responsibility' to send an ACK in responding to every (valid) Setup packet. This USB newbie's education continues.  :o

Thank you!

- Beethoven

P.S. I have another conundrum, but I will create a new post.