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

John E neurofog at gmail.com
Mon Nov 8 16:28:09 UTC 2010


What about using a FPFGA + High Speed AD Converter to make a DIY one?

John


On Sun, Nov 7, 2010 at 11:33 PM, Michael Prados <mprados at gmail.com> wrote:

> 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
> >> >
> >> >
> >> > --
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> >> >
> >>
> >>
> >>
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