PORTS Forum
Ports and Interfaces => USB => Topic started by: beethoven on March 20, 2012, 11:38:13 am
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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)
(http://HUB_MISSING_ACK_small.jpg)
Image of capture between (2.0) HUB and (1.1) device
(http://DEVICE_SENDS_ACK_small.jpg)
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]
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Looking at it quickly, I think it's a split interrupt completion. If so, this is normal behaviour. See Chapter 11.
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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.