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

[Dr. Jesus]

On Mon, Nov 8, 2010 at 3:43 PM, Michael Prados <mprados at gmail.com> wrote:
> One of the reasons I liked the comparison review I cited above was
> that it did a mini-teardown on the three USB analyzers it considered:
>
> http://www.summitsoftconsulting.com/UsbAnalyzers.htm
>
> Each of them seem to have a pretty similar architecture:
>
> 1. USB transceiver- takes care of the input differential waveform and
> any shenanigans on the line.
> 2. FPGA- breaks down the USB transactions, ties everything together
> 3. SDRAM- buffers the USB data
> 4. USB controller- to talk to the host PC
>
> For the cheapest option they test (the International Test Instruments
> 1480A hardware, which does 480 Mbits/s and retails for $500,) those
> components appear to be:
>
> 1. An NXP (now ST-Ericsson) USB transceiver like the ISP1504A.  $2.00
> @ quantity 1
> 2. An Altera Cyclone II FPGA like the EP2C20F484C7N, $56.30 @ quantity
> 1, with a dev kit available at $199
> 3. Some 32 MByte SDRAM, perhaps something like the Micron
> MT48LC64M4A2P-75:D TR, $12.67 @ quantity 1
> 4. Cypress FX2LP USB controller, $11.40 @ quantity 1
>
> So, we are looking at a BOM starting at $82.37.  I'd hazard a guess at
> $60 for the rest of the components, and a 4 layer board of this size
> at $200 @ quantity 10-20.  So perhaps $350 for a small run.
>
> I'm a mechatronic engineer, which means I am an electrical engineer
> once every three days :)  The PCB design on this would be challenging,
> because you have to sweat the signal integrity a bit.  Getting from
> the current state of open FPGA cores to what would be necessary to
> implement this is certainly a little intimidating.  The host side
> software is also a bit of work.

Wireshark already supports USB packet decoding, and modifying it might
be easier than reinventing something from scratch.

Did you have a look at any of the USB over Ethernet bridges?  Most of
the ones I've seen are significantly less than $350.  The one I used
was built into an access point, in fact, so it was basically free.
You don't get layer 1 information, but if you're just reverse
engineering a USB device it's more than sufficient.