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USB devices don't always work

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  • USB devices don't always work

    I'm using an Asus EB1501 eeeBox computer for my car pc. It uses a laptop type power supply, so I'm just using a laptop car adapter to power it. I've got the following USB devices plugged in:

    Behringer UCA202 USB soundcard
    XM PCR receiver
    BU-353 GPS receiver
    Lilliput 669GL-70NP/C/T HDMI touchscreen
    Bluetooth receiver from Rii Mini bluetooth keyboard

    I don't have any power management devices at the moment, so I just press the power button to turn off the PC when I turn off the vehicle.

    When I turn it off, the USB devices stay powered. When I turn the PC back on, sometimes the USB soundcard will not be found(and I've disabled all the other audio devices). The soundcard is plugged into the back of the computer, so I can't easily just plug and unplug it, so I have to reboot until it works. The bluetooth adapter also is occasionally unrecognized, and I can remedy this by plugging and unplugging it from the front of the PC.

    Is it possible that since the PC keeps all the USB devices powered that they get out of sync with the computer? Being that the devices are always powered, even when the PC is off, I would think they'd occasionally need a full reboot themselves.

    Has anyone else experienced these sort of issues?

    I'm going to add a powered hub next, so that I can add more devices. I'll set it up to lose power when the ignition is switched off, hopefully remedying this situation.

  • #2
    Yes, you are correct.

    USB devices need to be powered down during a shutdown or a hibernate for them to be recognized best upon re-start. However this is not always foolproof. U need to have good drivers for your devices to be recognized.

    There may be a setting in your laptops BIOS that will shut down USB power when the unit is shut down, but you are on the right track with a powered hub, that helped me out considerably.
    TruckPC - gutted, being used for test setup
    BoatPC - All in 1 in cuddy, N7 using VNC on dash, RR
    BlazerPC - Nexus 7 with Timur's USBROM

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    • #3
      Originally posted by DaveDog View Post
      Yes, you are correct.

      USB devices need to be powered down during a shutdown or a hibernate for them to be recognized best upon re-start. However this is not always foolproof. U need to have good drivers for your devices to be recognized.

      There may be a setting in your laptops BIOS that will shut down USB power when the unit is shut down, but you are on the right track with a powered hub, that helped me out considerably.
      Thanks for the quick reply. Unfortunately, there is no option on the eeeBox bios to disable USB power when the machine is off.

      It's not a laptop BTW. It's a small desktop, pretty much a netbook without a screen.

      Any other thoughts on this are welcome, and I'll buy a powered USB hub in the meantime to see what I can work out.

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      • #5
        ^^^ what enforcer said.
        I am running 3 four port self powered hubs and a dozen devices and have very few issues.
        My 2007 Ford F350 Work Log located HERE

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        • #6
          i have a very good solution, i will post soon, when hibernate it shutdown the usb device that you set..... and wake up, it re-enable the port !!!

          its in the carpc hd, i will post soon a topic with a good tutorial!!

          was so hard to found the solution, but that now i have you will see, its very simple!!

          dont need to buy anything else

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          • #7
            I'm Looking forwards to what you came up with.

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            • #8
              Sounds great! I'll be watching for it.
              My 2007 Ford F350 Work Log located HERE

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              • #10
                yes, its devcon..... =(

                look here guys, maybe help

                http://www.mp3car.com/vbulletin/gene...ml#post1431280

                Comment


                • #11
                  Guys, I am having a bit of a similar problem with USB devices, with a Terratec T1 TV tuner in particular.

                  My system is a HP t5720 thin client. I am running XP Pro on a SSD drive. I am NOT putting the computer into hibernate, as I am using the EWF (XPe enhanced write filter). I just turn it off, brutally.

                  So, first once the computer's booted was and working, I committed the current system state into the SSD. Now, it should be ok to cut the power to the PC at any time, and next time it will reboot to the same state as committed to disk. This works nicely.

                  But there is this funny thing: if I do shutdown the computer properly and boot up the next time, everything's working ok. BUT if I just cut the power, next time the computer boots without any shown errors (this is of course EWF doing its job right) but one of my USB devices (namely: TV tuner, which is the only "critical one") is not recognized! In fact it is "totally dead", no unrecognized devices in device manager either. Unplugging and replugging the tv tuner does the job, but I cannot do this every time...

                  Now, the interesting thing is, that because of EWF, there cannot be any changes taking place on the Windows boot volume. And by cutting the power I mean REALLY cutting the power from the computer and all USB devices (everything is totally powered off). So this is not the same as waking up from hibernation.

                  What could be the problem? Could it have to do with USB device enumeration done by the HP at the time of computer boot? Any ideas? I am thinking of trying to get HORM working - I might be able to resume to a state where the USB tuner is working right.

                  Thanks, Jouko

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                  • #13
                    How can a TV tuner in a car be 'the only 'critical one'?
                    Haha!

                    Now, looks like my issue is solved. First, got the HORM working - it greatly speeds up the booting process. It did not solve the TV tuner issue, but I then realized that the TV tuner comes back alive as long as the PC is shut off for more than 15 seconds or so... Something's keeping a power charge in there and if I power on the PC before everything´s really blacked out, the tuner dies.

                    Jouko

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