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Thread: Am I exhausting my USB inputs? How many devices is too much?

  1. #11
    Constant Bitrate
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    cool thanks guys... what i'll most likely do is power it via my PSU (5v)

    it'll work out perfect cuz i'm running a molex connector to the front to hook up my DVD-rom... so i'll tap into the 5v outta there and into the hub...

    can anyone recommend a nice small powered hub that will be easy to power up via this method?

  2. #12
    Maximum Bitrate jusatry's Avatar
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    Quote Originally Posted by Curiosity
    Go into Device Manager and look under Universal Serial Bus controllers. Double click on a hub and hit the Power tab. Also, it shows info like if it's self-powered it will say it and that each port can use 500mA.

    Right, but it cannot tell me how much power my....webcam....or iPod, or mouse is using, can it?

  3. #13
    FLAC
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    Yes.
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

  4. #14
    What can I say? I like serial. Curiosity's Avatar
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    Quote Originally Posted by jusatry
    Right, but it cannot tell me how much power my....webcam....or iPod, or mouse is using, can it?
    Sorry, yes it shows current in mA of each device, but only for devices on a hub. If you have something plugged directly into the PC, just unplug it and plug it into a hub temporarily to see how much it's using. With webcams (or others maybe) you might need to start up software that uses it to actually turn it on, then refresh the power display.

  5. #15
    FLAC
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    Hmm. Maybe my laptop ports count as hubs since I can plug anything in to find its current usage.
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

  6. #16
    Maximum Bitrate jusatry's Avatar
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    Wow. You learn something new everyday.

  7. #17
    Variable Bitrate heezer7's Avatar
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    Yeah, that is pretty cool. Weird though, it says my laptop have a lot more USB ports that it actually has. Lists 3x2ports and 1x6ports. Guessing that means there are 6 total but I only have 2 Wonder if there just arn't jacks for them or something...

  8. #18
    Maximum Bitrate jusatry's Avatar
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    could be unused MB headers?

  9. #19
    FLAC
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    Ok. So the USB ports on a laptop are still plugged into a 'hub' that's built into the PC. You may see more ports than are actually available because they use fairly generic chip sets and may only actually have a few physical ports. Some laptops even 'connect' internal devices to one of those ports that isn't accessible from outside.

    I just checked my car PC that I've just put into my car . I have a 4 port, unpowered 2.0 usb hub. It had:
    1. A keyboard (with a hub providing 2 more usb ports).
    2. A microsoft optical intellimouse
    3. A GPS receiver
    4. A USB 2.0 802.11g wireless fob.
    After using it for a bit, I got an error that the keyboard had malfunctioned and sure enough it wasn't working. I checked the power requirements of what was left hooked into the unpowered hub and it was 100ma for the mouse & GPS received and 500mA for the wireless NIC (unsurprising). However, everything is still working. Since the power requirement shown in the UI is the max (and USB only supports listing 100mA or 500mA), you can sometimes get away with exceeding the 500mA max if each device draws less than it's maximum claimed rate.

    Or it could be that the wireless NIC will use as much current as it's given without malfunctioning. So it's only getting 200-300mA and is simply losing range as a result. Still - it was doing better than my laptop which lost connection and didn't regain it until I came back inside!
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

  10. #20
    FLAC
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    But that latter theory doesn't match the fact that the keyboard failed because of insufficient current (it still works fine plugged directly into a m/b usb port).

    So you can get an idea what will definitely work, and you can get an idea what definitely won't work but there's a grey area in the middle where things might work or might seem to work except for occasional random failures...
    Progress: 80% - Permanent install left.
    Motion LS800 Tablet PC and dock.
    Vista, Bu-535 GPS, RoadRunner, MPT2006.

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