USB device without computer

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Hi there, I just need to known if there is possible to use a USB device
(flash drive, webcam, keyboard, etc.) with no computer interaction, so I
can use it in a specific application with a FPGA ????


Thanks in advance.

Re: USB device without computer

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You are confused.  A USB device will only work when it is talking to a
USB host, which pretty much has to be a computer.

But I suspect that when you say "computer" you mean "PC or MAC".  There
is no _fundamental_ reason that you couldn't implement a USB host on a
sufficiently large FPGA.  The easiest way would be to use an FPGA with an
embedded PowerPC or ARM processor and run an embedded Linux system on it
that is big enough to support a USB host.  Regardless of how you do it
you'll find that implementing a USB host is not the world's lightest-
weight systems programming task, in any way, shape or form.

--
www.wescottdesign.com

Re: USB device without computer

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Why the heck embedded linux ? There are embedded USB host stacks (e.g.
from HCC Embedded) which run even without an (RT)OS.


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42Bastian
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Re: USB device without computer

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Eh -- apparently I'm behind the times.

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www.wescottdesign.com

Re: USB device without computer
Can you explain more, This project should work without any computer
interaction, so I am surprised about this solution.



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device

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Re: USB device without computer
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Either you know something that the experts here do not understand, or it
really can not be done.


If you do know something, please share with the rest of us.


don

Re: USB device without computer

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What everybody is telling is that you can't do USB host-side
without a computer.  Your choices are to use a computer makde
from off-the-shelf parts/SW or build something custom.

What you're asking is in effect "I want to run a large, complex
computer program without any computer." Putting it all into an
FPGA isn't going to make it any less a "computer".

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Re: USB device without computer

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Perhaps what we have is simply a semantic problem.

The engineers are saying that practically speaking, doing host-side
USB requires a computer or a an absurdly more complex bit of dedicated
logic.  But when we say "computer" we do not necessarily mean
something with a keyboard and an LCD flatscreen, which is what the
word may mean to users, product managers, whatever.

Instead, what we mean is an essentially fixed hardware engine
executing a program.  The complexity is in the sequence of
instructions rather than in the architecture of the engine itself.

Such "computers" come is all shapes and sizes today, most of which -
the ones we call embedded processors - are probably not considered
computers by non-engineers.

There are many physically compact solutions to the poster's problem -
in fact there are now single-IC solutions because you can now by
processors with USB host peripherals and the necessary RAM and ROM
stacked on top - used in cell phones for example.

Re: USB device without computer
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AFAIK: There is minimal host functionality implemented in the
  USB OTG devices. They are still computers of course.
(typical example would be a camera directly connected to a printer)

http://www.usb.org/developers/onthego

/Rolf

Re: USB device without computer

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What are you refering to ? (Top posting is sometimes bad, isn't it ?)

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I have the feeling, you do not have the slightest idea of what you
want to do in your project.

Please define: Computer.

Then we might give you more hints.



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Re: USB device without computer
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"Should" --- says who?

Re: USB device without computer

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I should be 20 years younger, better looking, and rich. So I,
too, am surprised about "this solution".  :)

--
Grant


Re: USB device without computer

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You don't need a 32-bit RISC chip with Linux; a PIC24 can operate as a USB
host.


Re: USB device without computer
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Theoretically it is possible to do USB in state-machine-logic, but in
practice it is not wise to attempt to handle the higher protocol
layers that way.

What you end up doing is using a micro controller (small, embedded
computer) either as a discrete chip, in the form of a specialized USB-
to-SPI or whatever adapter, or constructed within the fabric of the
FPGA itself.

Re: USB device without computer

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Keeping in mind that you're implementing a USB _host_ stack, which is a
heck of a lot more work than implementing a USB _client_ stack.

--
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Re: USB device without computer
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Yes.  And even most of the device/client stacks are practically going
to use a micro controller type of architecture.

I see the link to the usb-to-spi device has been posted in the thread
already.   This is of course a microcontrollor with the necessary
firmware built in.

Re: USB device without computer
Op Tue, 16 Jun 2009 18:35:36 +0200 schreef Tim Wescott  
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Nowadays people buy & integrate their stacks, not implement them.  
Implementing USB host would be crazy, unless you think you can do it  
better than the competition.



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Re: USB device without computer

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And most of the time that craziness would manifest itself in thinking
you can do that.

Re: USB device without computer


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I developed a RTOS.
We developed TCP/IP stack.
We developed POSIX compliant file system (flash file system on the way).
USB host is not quite there yet, but it will be in the near future.

It's not all that hard to do, and it turns out to be actually better20%
then many commercial solutions; and of course there is no comparison to20%
the free opensource trash.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com



Re: USB device without computer
On Thu, 18 Jun 2009 10:20:11 -0500, Vladimir Vassilevsky

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And that all only for in-house use ? You're crazy. I hope your boss
has bound you with a slave-contract otherwise he might loose a lot of
money and know-how at the time you quit.

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