USB 2.0 Experiences

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I'm about to design a peripheral that needs a guaranteed feed of data at
about 50 MBits/sec from a PC.

USB 2.0 looks like a contender, so let's assume we go that way.

We do not want to have much intelligence in the peripheral.  Basically, it
just needs to act as a window onto some hardware registers, and set up the
data transfers.

What is the longest interruption of USB data transfers we are likely to see?
The peripheral is like a printer that cannot do start/stop so the data
stream must keep up with it.  That will determine the amount of buffering.

Given we probably need multiple end points, how do we stitch the data
streams together?

What is a good USB/processor combination?  As we are talking low volume,
chip cost is probably not as important as the ease of implementing the
peripheral firmware and the PC side driver.

I've been reading USB Complete (2nd ed) by Jan Axelson.  Any other
recommendations?

Is there a news group for USB?

Many thanks,
   Bill



Re: USB 2.0 Experiences
: I'm about to design a peripheral that needs a guaranteed feed of data at
: about 50 MBits/sec from a PC.

: USB 2.0 looks like a contender, so let's assume we go that way.

Look at www.comsec.com/wiki for an example of the Cypress FX2 as a fast USB2
datapump.

Bye

--
Uwe Bonnes                 snipped-for-privacy@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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Re: USB 2.0 Experiences
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Nothing about Cypress FX2 at www.comsec.com/wiki !!!

Larry
www.amontec.com

Re: USB 2.0 Experiences
: > : I'm about to design a peripheral that needs a guaranteed feed of data at
: > : about 50 MBits/sec from a PC.
: >
: > : USB 2.0 looks like a contender, so let's assume we go that way.
: >
: > Look at www.comsec.com/wiki for an example of the Cypress FX2 as a fast USB2
: > datapump.
: >
: > Bye
: >

: Nothing about Cypress FX2 at www.comsec.com/wiki !!!

Sorry, try:

http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral
--
Uwe Bonnes                 snipped-for-privacy@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
We've slightly trimmed the long signature. Click to see the full one.
Re: USB 2.0 Experiences

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Depends on what mode of transfer (bulk, isochronous, ...) you choose,
what other devices you put on that USB link, and how busy the PC is
doing other kinds of I/O.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: USB 2.0 Experiences
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You could consider SpaceWire as a much simpler pt 2 pt alternative
which is easily able to do low 100Mbits over twisted pair. Its an IEEE
std 1355 and there is IP in FPGA for it and PCI boards, check out

http://www.4links.co.uk /

It comes from the remnants of the Transputer project T9000 phy level
links which got a life of their own.

regards

johnjakson_usa_com

Re: USB 2.0 Experiences
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Look at the FX2 family of chips from Cypress Semi.  

You will probably want to use a BULK transfer mechanism.  Given that,
it is possible to have an infinitely long delay between packets.
However in actual practice the delay between packets will be dominated
by your PC's processor load, its USB hub controller and the software
you write for sending out your data.

You may be able to use a single endpoint for the data stream but keep
in mind that USB data is not a continuous stream like you might be
used to with say RS232 serial ports.  USB data is sent in packets.
You can get a perceived continuous stream by feeding you packets into
a FIFO and then unloading the FIFO at a fixed rate.  This is something
the FX2 chips are very good at accomplishing.

There are several issues you need to deal with on the PC side and
companies like Andrew Pargeter & Associates (www.devicedriver.com I
think) and Jungo will be helpful.  Andrew's company has been
particularly helpful to me in answering some of my questions.

Rob Young
snipped-for-privacy@ieee.org

Re: USB 2.0 Experiences
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Besides the well known FX2 from Cypress (look for the new A version, low
power..), give also a look to NetChip (now PLX) NET2272.

I purchased theirs PCI RDK (developers kit); basically, it's a PCI board
that carries the NET2272; you can then develop your target side firmware on
a standard PC, using Visual C++.

So far, I'm really satisfied with it. It's very productive to work with, and
their support is good.
Comes with source firmware for many apps.

See http://www.plxtech.com/products/NET2000/NET2272/default.asp .

If at all possibile, choose a standard profile that's supported by the OS,
you'll save yourself a lot of trouble.

Here you can find a list of Windows supported classes:
http://www.microsoft.com/whdc/system/bus/usb/USBFAQ_intro.mspx

This is the generic MS page on USB:
http://www.microsoft.com/whdc/system/bus/usb/default.mspx

I do not know Linux enough to give you some notes on it.

If you need help for MS drivers, there's a lot of know how out there. Some
links:

http://www.oneysoft.com/ (buy Walter Oney book, it's excellent)
http://www.probo.com/ Do not know them...
http://www.jungo.com/ A market standard...
http://www.drivertools.net/ Very responsive

in no particular order.

Good luck!





Re: USB 2.0 Experiences
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Whopps.... the low power version it's the FX2LP.

Sorry.



Re: USB 2.0 Experiences
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Bill,

I think that you should look at FireWire it is much more robust and
may be a good fit. It is not as cheap but it may provide extra
flexibility as its architecture and configurations are flexible.

Bob McWilliams
Zendex

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