[Noisebridge-discuss] cheap USB Analyzer, or signal integrity tools?

Mon Nov 8 07:33:41 UTC 2010

Thanks for taking a look, Erik.  The Bus Pirate does not appear to
support USB, and in any case, the PIC 24F maxes out at 16 MIPS, so it
wouldn't be capable of interfacing with High Speed USB at 480 Mbit/s.
I'm sure it's useful for other things, and probably about time I
checked one out.

I've been searching on these and similar terms, and have not been too
satisfied with the results.  Some of the high speed capable USB
analyzer peripherals might be worth the cost, though.  Here is one of
the better comparisons I've seen:

http://www.summitsoftconsulting.com/UsbAnalyzers.htm

They seem pretty fond of this unit, which is a relative bargain at
$500 (compared to some of the $20k options I've seen):
http://www.internationaltestinstruments.com/StoreFront/Store_Prod1_1480A-USB-20-Protocol-Analyzer.aspx

Still not open source.  And none of these seem to tell you anything
about signal integrity, still seems like you have to put some serious
cash into a multi-GHz scope to do any kind of signal integrity work.

In general, the cost of electronic test equipment goes up with
frequency, so it's not so surprising that there are so few cheap
solutions.  But on the other hand, USB 2.0 is approaching a decade
old, and is ubiquitous and cheap (via lots of mass produced chips.)  I
think it's a shame that the debug tools are still a bit inaccessible.

-Mike

On Sun, Nov 7, 2010 at 10:40 PM, Erik Nelson <erik.nels0n99 at gmail.com> wrote:
> I remember it doing USB:
> http://www.google.com/search?q=bus+pirate
> http://code.google.com/p/the-bus-pirate/
> ..Maybe not.
> http://www.google.com/search?q=open+source+usb+analyzer
> Or the latter-
> http://www.google.com/search?q=open+source+usb+analyzer+protocol
> Hope this is any help at all.
>  -- Erik
>
> On Sun, Nov 7, 2010 at 8:47 PM, Michael Prados <mprados at gmail.com> wrote:
>>
>> PS There are a few devices out there that plug into PC's to act as
>> signal analyzers, and these solutions are definitely cheaper than
>> traditional self-contained analyzers.  Here are a few of these:
>>
>>
>> http://www.totalphase.com/solutions/apps/usb_analyzer_guide/?gclid=CJaL-8CjkKUCFQdMgwodikvvMw
>>
>>
>> http://www.lecroy.com/ProtocolAnalyzer/ProtocolOverview.aspx?seriesid=216&capid=103&mid=511&gclid=CJTDkcOjkKUCFQoBbAodqiCIQA
>>
>> http://www.saelig.com/UA/UA016.htm
>>
>> http://myspot.neteze.com/~calfee/
>>
>> These are still a bit pricey, they don't appear to be open source ,
>> and it doesn't look like any of them help you with signal integrity
>> issues. Any one use one of these?
>>
>>
>> On Sun, Nov 7, 2010 at 7:19 PM, Michael Prados <mprados at gmail.com> wrote:
>> > Hi All,
>> >
>> > This has been a topic of increasing interest to me, as USB becomes
>> > less of an optional luxury in hardware hacking and more of a
>> > necessity, and it's come up again lately in the context of Adafruit's
>> > bounty for the Kinect:
>> >
>> >
>> > http://www.adafruit.com/blog/2010/11/05/our-kinect-arrived-today-you-gonna-get-modified/
>> >
>> > So many devices that I care to use or build have a USB interface, and
>> > there are a lot of tools out there for embedded device developers to
>> > add this functionality.  That is all well and good when it just works,
>> > but frequently the reality is less than ideal.  Here's some scenarios
>> > I've had to deal with:
>> >
>> > * the interface for a USB device is not, or not fully, documented
>> > * the interface for a USB device is nominally documented, but doesn't
>> > perform exactly as the documentation suggests
>> > * environmental noise, connector, or transmission line issues lead to
>> > signal integrity problems (not to mention PCB design issues!)
>> > * you make a working system, set it up somewhere where it is difficult
>> > to maintain, and the USB subsystem stops working. How can you diagnose
>> > it remotely, or outside of the lab?
>> >
>> > Traditionally, for signal integrity issues- essentially physical layer
>> > issues, you need a high-bandwidth oscilloscope.  I feel like it is not
>> > unreasonable for a hacker to get a hold of a 100 MHz scope, which
>> > might suffice for Full Speed USB, but for High Speed USB at 480
>> > Mbits/sec, you need a scope at up around 2 GHz or above.  Even a used
>> > scope in this range typically runs $5k and up.  And heaven forbid you
>> > need to debug a problem outside of the lab- are you going to strap
>> > your nice scope to the top of a car, or a helium balloon?
>> >
>> > What I really fantasize about for the physical layer is a
>> > self-diagnosing USB hub.  Imagine if your hub could provide even a
>> > rough estimate of the eye size.  Has anyone encountered anything like
>> > this?
>> >
>> > So far as the data layer, this is where the USB Analyzer typically
>> > comes in.  It seems to cost about the same as the multi-GHz scopes.
>> > For this, it really seems like something running on Linux, perhaps
>> > with special hardware, could do the trick.  Anyone encounter something
>> > like this?  I've used Windows based USB monitor software before, but
>> > I've found this kind of limiting, especially if you can't run this
>> > software on the host device.
>> >
>> > All too frequently, I end up resorting to RS-232 or RS-485 when I have
>> > the choice.  This may still be right decision, even in 2010, but I
>> > hate to be forced into it by the inaccessibility of good USB debug
>> > tools.  Seems like a major barrier to hardware hacking, which is only
>> > going to get worse if a next generation technology such as USB 3.0 or
>> > Light Peak gains in popularity.
>> >
>> > Any one have some good solutions to these problems?  I'll probably
>> > post elsewhere too, but I figured on giving it a try here first.
>> >
>> > -mike
>> >
>> >
>> > --
>> > [REMOVE THIS TEXT BEFORE SENDING AN EMAIL!]
>> >
>>
>>
>>
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