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Discussion in 'Electronic Design' started by Don Y, Mar 30, 2012.

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  1. Don Y

    Don Y Guest


    I was connecting another 4 port USB hub to a machine
    tonight "identical" to one already in service, there.
    Once in place (and operated in the same fashion as
    its sibling predecessor), it failed to operate as
    expected! (i.e., PC wouldn't enumerate any of the
    drives attached).

    Suspecting the hub might be bad, I tested it elsewhere.
    Replaced cables. Added external power source. etc.
    Works like a champ on another machine (with different
    devices dangling off of it).

    [remember, "old" hub still works fine on the machine
    of interest]

    Tried a *second* hub (which is actually the *third* of
    this type being discussed) with similar absence of joy.

    After enumerating the behaviors of the three different
    hubs (one "good", two "bad" -- yet all *functional*),
    I took a peek inside. Of course, different chipset
    in the good vs. bad ones.

    <shrug> Aside from an intellectual curiosity, this is
    not a real issue for me *personally*. I'll just pick up
    another couple of hubs.

    But, I had been debating what to use for external interconnects
    on a high volume project. USB (host) *seemed* the natural
    choice. It's always "just worked" (for me) in the past!

    In light of this little experience, I started thinking about
    how I would respond to a customer making the claim that *my*
    device "wasn't working" -- when he attached (this particular)
    hub/device. Yet, *swearing* to me that these things worked
    properly "elsewhere".

    I've been giving serious thought to using ZigBee/BT for
    external device connections as it offers several other
    advantages over USB (no wire tangles, longer "virtual" wires,
    no cables to keep track of, no connectors poking through
    the case, no galvanic paths back *into* the device, no
    concerns about supplying "enough" power to the external
    devices, etc.). Of course, the ubiquity of USB and the
    huge cost advantage have (previously) been weighing against
    the wireless approach. :<

    So, for folks with USB-capable (host/slave) devices, what
    have your experiences been:
    - problems as a host NOT recognizing some bit of COTS
    kit dangling off your port (that the user thinks you
    *should* be able to recognize -- e.g., "generic hub")
    - problems as a slave NOT being recognized *through*
    some particular combination of fabric to the host
    And, how do you address these problems when interacting
    with the customer? How happy is he/she with your
    remedy ("buy a different hub", "buy a different disk
    drive/printer/smokeshifter", "plug in the cable BEFORE
    applying power", "plug in the cable AFTER applying power",

    (I.e., the wireless solution may win because it is LESS
    ubiquitous... less likely to be "expected" to talk to
    "anything with the correct connector onboard")

  2. Sounds like they didn't get the firmware right on the new chip type.
    I'd say that even though it works "elsewhere", it MUST have a spec
    conformance failure to not function as the spec demands.

    What brand is it? I want to be sure to avoid them. Especially if you
    let them know about it, and they fail to fix the problem.

    Swap out the old one for it and see if it works "in place of" the
    original. If it doesn't, you have a legal case, but depending on the
    maker, that may not matter. A bigger maker will want to make it right,
    at the product level at least. A chinese shit shop wont.

    There should be a web site somewhere where we list bad designs and their

    I hate going to Fry's and having to buy things I have no example of the
    working of.
  3. Don Y

    Don Y Guest

    Hi Joel,

    Are these cases where *you* implemented the host and (later)
    encountered sticks/hubs that "you" couldn't enumerate?
    Or, cases where you plugged a stick/hub into some other host
    (e.g., PC) and encountered problems? [The remedies are
    obviously different :> ]
    Yes -- though (many) hubs are almost as cost-minimized!

    In this particular case, I know the devices (USB drives)
    are recognized by the PC. *Other* hubs allow the devices
    to be enumerated properly. The "new" hub is recognized (as
    a "Generic USB hub"). *Other* devices enumerate properly in
    the hub. But, these *particular* devices won't enumerate
    behind this particular hub.

    When I get a chance, I will systematically try different devices
    and hubs to see if this is a common problem (I've not encountered
    it before). Then, for those that don't seem right, I'll try
    a couple of other OS's to see if it's something that can be
    handled with a fixup table in the OS (or if it is a genuine
    "defect" in the hub/device). The "next" hub that I pulled out
    of the hub box worked fine (as had the one used prior to the
    "new"/bad one). I'll have to peek inside any that "don't work"
    and those that "do work" and see if there are any common aspects
    (perhaps a particular controller with "issues"?)
    Yes. The same holds true of "N-in-1" memory card readers, etc.
    But, in each prior case, the physical device was at least
    *acknowledged* in the enumeration. These devices look like
    they aren't even *seen* (by the hub *or* the PC).

    I'll use other OS's with more verbose reporting to get a better
    look at what is actually happening when the devices are plugged,
    Understood. A "justifiable" design decision -- though perhaps
    not obvious to the end user (who just sees a USB connector and
    wonders why he can't do what he does *elsewhere* that connector

    One crude analogy that probably users would easily relate to:
    adding a cube-tap on the end of an extension cord. I.e., to
    them, the hub just looks like a "connector multiplier" -- much
    the same as a cube tap represents an "outlet multiplier" for
    the extension cord.

    They've got a bedside lamp plugged into the extension cord and
    it's worked fine. They plug in a clock radio and *it* works
    fine, as well. They plug in the cube tap (so they can use the
    clock radio and lamp at the same time) and the lamp no longer
    works -- but, the clock radio *does*! Suspecting a bad outlet
    in the cube tap, they swap the connections of lamp and radio
    (expecting the *radio* to now fail) and the radio *still*
    works (using the cube tap outlet that had failed to light the
    lamp) AND the lamp still doesn't work (using the outlet that
    had previously powered the radio)!

    If someone were to describe this behavior to you (the manufacturer
    of the radio, clock or extension cord), you would be tempted to
    "conclude" that the user was "confused" :> Surely that can't
    be an accurate description of the situation!! (?)
    Agreed. The "advantage" BT (and ZB even moreso) has is that it
    *isn't* as ubiquitous. People don't expect to plug "anything"
    into (e.g.) their phone (via BT). There are just far fewer
    BT "offerings" to entice/corrupt the user.

    OTOH, people see a USB connector and they figure they can plug
    anything into it "just like on their PC" -- begrudgingly
    acknowledging that they might need to find a *driver* for the
    device... but, the system will *see* the device and tell them
    about this missing driver (whereas this appears to be a case of
    the system/PC not even *seeing* the devices behind the hub).
  4. I had a PNY Attache that did not work in a Intel board, worked fine in
    any other hub.
    But an older model of the Attache worked fine in every hub I tried.

  5. miso

    miso Guest

    I'd suggest D-Link or Belkin. Not that these people are brilliant, but
    they tend to have something that resembles customer service. Generally
    D-link makes good stuff.

    One painful idea would be to get a small industrial SBC that has
    sufficient USB connectors and roll your own hub. I've seen single board
    computers with 14 usb ports.
  6. Don Y

    Don Y Guest

    I'm not concerned with solving "my" hub problem -- I simply
    dug another out of a box and replaced the "problem" hubs.

    What concerns me as a developer is how a potential customer
    might find himself in a similar situation "blaming" my
    product for a problem that is "beyond my control" -- a
    bad hub design or "external device".

    I will examine the hub, other hubs and other devices to see
    to where this "fault" can be attributed. Likewise, the host
    OS (hard to imagine MS wouldn't have stumbled across a problem
    like this and installed a fixup workaround *if* the problem
    can be handled "in software").
    As I said, I am not worried about my personal needs. I put
    a couple of 7 port hubs on the machine in addition to the
    four port hubs there already. It's main appeal to me is
    as a test bed on which I can get repeatable failures in
    the USB "field" subsystem. (I will have to check the problem
    hubs on other machines as well)
  7. A few years ago we bought a $10,000 signal generator. It came with a 128MB
    USB stick. This, I assume, is because this stick actually worked while a
    random stick lying around might not have. Of course, the stick got
    'borrowed' when someone needed one for something else and we now have to
    play pot luck like everyone else (or we would do if anyone actually used the
    USB connection).

    One solution to both these problems would be to simply change the connector
    for one that isn't standard. No problems with users trying incompatible
    parts, and no standard parts 'wandering'. But as a user I'm not exactly
    thrilled with this idea...

  8. Don Y

    Don Y Guest

    Hi Theo,

    Or, just a "convenience issue". Sort of like giving gifts to
    young children complete *with* batteries (so they don't start
    nagging their parents immediately to go BUY those batteries!)
    That's the appeal of the wireless solution.

    Nowadays, it would take very little time for <someone> to publish
    a description of how to build an "adapter cable" to work around
    the proprietary connector. Then, you're spending customer service
    dollars troubleshooting external devices that were never intended
    to mate to yours (since a wise customer would carefully withhold
    the "little detail" that he now has a 4TB USB drive plugged in
    where the 128MB memory stick was intended to be placed -- since
    admitting this "hack" would undoubtedly immediately be met with
    The Party Line of "We don't support other devices. Use of such
    devices may void your warranty." yadda yadda yadda)
    If you can obtain the "peripherals" that you can "reasonably" be
    expected to want to connect to the device in question (and, at
    "reasonable" prices), the biggest hassle I see is the risk of
    *losing* that peripheral (your case). Similarly, damaging it.

    Or, trying to support the device beyond it's published end-of-life
    (I keep an XT keyboard around for an old logic analyzer that is
    not fond of AT keyboards!)

    The complexity of something like a wireless link sets the bar
    considerably higher for "unapproved attachments".

    I'm just disappointed that USB isn't as universally *implemented*
    as its ubiquity would suggest...
  9. Paraphrasing Jamie Zawinsky: "You have an USB problem. You are trying to
    solve it by using Bluetooth. Now you have two problems."
  10. Klinger

    Klinger Guest

    Your (her) count would be off by a minimum of one as well. You forget
    the user. That's three problems in this instance.
  11. Klinger

    Klinger Guest

    The typical device these days is a micro SDHC. Typical, at least as it
    relates to modern design for thing like cameras and MP3 players, and
    Oscopes, etc.

    They fit into a tiny slot, and are usually left in place. The only
    reason to remove it is to do a snail transfer to it, and then replace it
    again. One can also make a holder with an eyelet and a lanyard, keeping
    it attached to the product it was made for.
  12. Guest

    I had a couple of Belkin USB hubs that were flaky as hell, well, until they
    just went dead. Belkin is over-priced crap, as far as I'm concerned. Might
    just as well buy non-name Chinese junk.
  13. miso

    miso Guest

    But Beklin, Dlink, and probably Linksys is just Chinese ODM. Linksys
    probably does their own coding.

    I'm not a big Belkin fan. I did like their insane lifetime replacement.
    However, I haven't had good luck with any of their high tech stuff. Even
    USB to 232 converters. Dlink on the other hand makes stuff that works,
    but support doesn't last very long.
  14. WoolyBully

    WoolyBully Guest

    Linksys is owned by Cisco, you stupid twit.
  15. miso

    miso Guest

    When did I say Linksys wasn't owned by Cisco?

    The designs on the consumer grade stuff are still ODMd, but firmware
    comes from Linksys. That was why they bought Linksys in the first place.
    They needed a different business model to get into the consumer router
    market. Cisco was already making routers at the time, but not with that
    business model.
  16. So **** OFF AND DIE, you retarded KOOK!
  17. Klinger

    Klinger Guest

    Flash drive slots? Yeah, newer jobs do.
  18. WoolyBully

    WoolyBully Guest

    You are a complete retard.

    The designs are ALSO CISCO's. THEY DESIGN IT. They have it
    MANUFACTURED in Asia, you fucking retard!
    You are an idiot. The firmware is a cut down version of their pro
    firmware. It is ALL CISCO's, you fucking idiot.
    You ain't real bright, boy.
    CISCO was making routers before you knew what one was. I am quite sure
    they and I will get along just fine without your pathetic spouting of
    what you claim are statistical facts.

    You are, in fact, 100% clueless.
  19. josephkk

    josephkk Guest

    Actually no, Linksys uses a lot of FOSS. The others likely do also.

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