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John Ford wrote:<br>
<blockquote type="cite"
cite="mid16436.50636.709056.746271@gargle.gargle.HOWL">
<pre wrap="">Martin Shepherd writes:
>
> Since the teleconference yesterday, I have been searching for a
> single-board computer (SBC) with a USB 2.0 interface. It turns out
> that my belief that USB 2.0 is currently very rare in SBCs, was
> correct. I haven't been able to find any PC104 or PC104+ form-factor
> boards with USB 2.0. Those PC104+ boards that do have USB interfaces
> at all, have USB 1.1.
>
> The only thing close that I found was a sole EBX form-factor board
> with USB 2.0, as shown at:
>
> <a
class="moz-txt-link-freetext"
href="http://www.commell.com.tw/Product/SBC/LE-362.HTM">http://www.commell.com.tw/Product/SBC/LE-362.HTM</a>
>
> SIZE: 146mm x 101mm (5.75" x 4.0")
> CPU: VIA Eden 667MHz or 800MHz CPU
> PSU: 5V (current not specified)
> I/O: 2 USB 2.0 ports, 1 parallel port, 1 RS-232, 2 IDE etc...
> RAM: Up to 512MB.
> ETH: 10/100 Base Tx.
>
> A downside of this board, is that it doesn't have standard connectors
> for the I/O ports. Instead it uses headers that would have to be wired
> up to our own standard connectors. This would, in turn, require us
> to provide something to mount these connectors to.
This is not really a problem, as we have to use RFI connectors on
there anyway.
<a class="moz-txt-link-freetext"
href="http://www.mycomp.com.tw/Products/embedded/EB5-240.htm">http://www.mycomp.com.tw/Products/embedded/EB5-240.htm</a> is another
one. It has 4 usb 4.0 ports, 4 serial ports, Ethernet, etc. It also
has the VIA low-power cpu.
Advantech,
<a class="moz-txt-link-freetext"
href="http://www.advantech.com/products/Model.asp?Category_ID=1-D6LBQ&bu=">http://www.advantech.com/products/Model.asp?Category_ID=1-D6LBQ&bu=</a>
has several 5.25" form factor PC's with USB 2.0
Here's another with 4 USB 2.0 ports:
<a class="moz-txt-link-freetext"
href="http://www.icp-australia.com.au/PDF-Data/nova8890.pdf">http://www.icp-australia.com.au/PDF-Data/nova8890.pdf</a>
Here's maybe my favorite:
<a class="moz-txt-link-freetext"
href="http://www.emacinc.com/sbc_pc_compatible/pcm_9577.htm">http://www.emacinc.com/sbc_pc_compatible/pcm_9577.htm</a>
(I suppose if we had 4 separate usb ports, we would not need USB 2.0, no?)
>
> I also found a small number of ETX form-factor SBCs with USB 2.0. At
> first sight, these appear to have small form factors, but it turns out
> that they are designed to be mounted on ATX size daughter boards, and
> thus, again, don't have any of the standard external connectors.
>
> Other than the above SBC from Commel, the only suitable candidate
> boards that I found were a couple of Mini-ITX style boards. These are
> really designed for small standalone computers, rather than embedded
> computers, but are also being used by hobbyists for all kinds of
> embedded projects. They include all of the standard connectors on the
> board, so they would be more convenient than the EBX board mentioned
> above, despite being a bit bigger.
>
> The first one is the Thunderbird from Lippert (a German company).
>
> <a
class="moz-txt-link-freetext"
href="http://www.lippert-at.com/index.php?id=21">http://www.lippert-at.com/index.php?id=21</a>
>
> SIZE: 170mm x 170mm (6.7" x 6.7")
> CPU: Intel Pentium M (900MHz to 1.6GHz)
> PSU: 5V (24.5W at 1.6GHz, 7.0W at 900MHz)
> I/O: 6 USB 2.0 ports, 1 EPP parallel port, 2 RS-232, 2 IDE etc...
> RAM: Up to 1GB.
> ETH: 100/10 BaseT, 1000 BaseT.
>
> Note that since this board has 6 USB 2.0 ports (4 of which have
> board-mounted standard USB sockets), we wouldn't need an external USB
> hub.
This one is very cool.
>
> The other suitable Mini-ITX board that I found was the Envader III
> from EEPD (another German company).
>
> SIZE: 170mm x 170mm (6.7" x 6.7")
> CPU: Intel Pentium M (1.1GHz to 1.6GHz)
> PSU: 5V (typical power consumption 17-30W)
> I/O: 4 USB 2.0 ports, 1 EPP parallel port (shared with floppy),
> 2 RS-232, 2 IDE, Firewire etc...
> RAM: Up to 1GB.
> ETH: 10/100 BaseT
This one too.
> In summary, there aren't many options, but if we do go with the
> requirement for USB 2.0, my preference would be to get the Lippert
> Thunderbird mini-ITX board.
Sounds fine. It may come down to price. We'll need 3 or 4 of them.
Do any of these companies provide a Linux port? emac does, and
possibly ampro
John
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</pre>
</blockquote>
All,<br>
<br>
It would certainly appear that we have several options to choose from
regarding<br>
possible SBC candidates...<br>
<br>
John... your parenthetical comment (question) regarding a possible fall
back to<br>
USB 1.1 with the advent of 4 USB "ports" at the host raises an
important point.<br>
<br>
I've been studying the actual (650 page!) USB 2.0 specification in my
spare time<br>
over the past few days and have learned some interesting tidbits about
both the<br>
2.0 and 1.1 standards...<br>
<br>
USB 1.1 supports two basic transfer rates... there's "Full Speed" at
12Mbps and<br>
"Low Speed" at 1.5Mbps (here, both are expressed in bits (not Bytes)
per second).<br>
However, the 1.1 standard calls for <u>all</u> transactions to be
carried out (factored into)<br>
fixed-length "Frames" of 1mS each. This frame rate is pretty much set
in concrete <br>
by the standard and carries some implications regarding bus access
allocations,<br>
issuance of multiple, time-critical command packets, etc. Since our
instrument's<br>
current specification calls for a 1mS polling interval, this might
create a problem...<br>
<br>
On the other hand, USB 2.0 operates at a maximum transfer rate of (up
to)<br>
480Mbps and utilizes what's referred to as "Micro Frames" which
are125uS <br>
in length. It seems to me that this 8X increase in effective frame
rate would <br>
be
highly desirable given our intent to poll the CCB at 1mS intervals...<br>
<br>
Randy<br>
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