USB errors handling/statistics

Posted: 3 years ago Quote
Hi ITIC.

According to USB specification (Rev. 2.0, April 27, 2000):
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4.5.1 Error Detection
...
The protocol includes separate CRCs for control and data fields of each packet. A failed CRC is considered
to indicate a corrupted packet.
...

4.5.2 Error Handling
The protocol allows for error handling in hardware or software. Hardware error handling includes reporting
and retry of failed transfers. A USB Host Controller will try a transmission that encounters errors up to
three times before informing the client software of the failure.
...
----------------------------------------------------------------------

I'd like to know if your analyser:
1) can detect all errors and silent retries, and
2) can gather long statistics on such errors.

In other words I'd like to collect information about connection quality (not protocol details) for a long time (many hours).

Also is this possible to use single computer instead of pair "host-analyser"?

TIA for answer.
Posted: 3 years ago Quote
The 1480A will indicate bad CRCs as they are viewed on screen but there is no statistics gathered. The trace will show all resends and retries since these will show up as part of the regular protocol decoding. A USB Analyzer is not really suited to gather long captures like this; if the link is suspected bad then an oscilloscope should be used to measure the actual signal integrity via eye diagram. It is possible that other vendors have USB analyzers that allow you to trigger on CRC errors. The 1480A currently does not have such trigger capabilities (which is why it is much lower priced than any other competing unit).

And, yes, it is possible to use a single computer. You would need to use two separate host controller cards.

See this support forum post for details: http://www.internationaltestinstruments.com/boards/t/45/how-to-connect-the-1480a-usb-cables.aspx