Josh Koffman <PICLIST@mitvma.mit.edu> wrote:

> There is a local store here that I've seen USB A-B cables in 25
> foot lengths. Now, the packages could be mislabeled, I'm not sure.
> These are the no name, made in China imported jobbies. These cables
> would seem to be definately out of spec. They are not powered
> extensions, they don't have a big enough "hump" on the cable. If I
> read your post correctly, having a cable that long could damage the
> drivers, correct?

    It could, yes.  In the real world, it probably won't, but it's
    certainly out of spec.

    The trademarked USB logo is legitimately carried only by products
    (including cables) that have passed USB compliance testing.  Lack
    of a logo is a good clue that you're looking at a non-compliant
    (or at least non-tested) product.

> So why would anyone make one that long?  Is it possible that it
> might work?

    Sure, it could work.

    Using a 25-foot cable is loosely analogous to overclocking a PC
    video card (or a PIC):  In any specific system, it may work well
    enough for a particular application, but it may not meet all of
    its specifications... And under those conditions, it's certainly
    not guaranteed to do so by its manufacturer.

    -Andy

=== Andrew Warren -- aiw@cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

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