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

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

    I've got a MII board... and it's got 2 onboard USB2.0 built-in (and i can hook up 2 more if i get more USB connectors)

    anways... i plan to run a non-powered 4 port hub to the front of the car (PC is in trunk) and hook up (DVD rom, keyboard, flash drive, touch screen)

    and run another 4 port hub off the 2nd USB port to run: GPS, bluetooth, game controller, and possible webcam.

    will i be fine? Or will i need to power the front 4port hub? And if so... how?

    thanks

  • #2
    I'm not 100% on this, but you may be better off powering both hubs. I know the USB port supplies something like 500mA of current w/ 5V of voltage, so you figure that current will now be shared among 4 devices. If your devices can deal w/ 125mA each (500mA/4), then you'll be fine.

    As I said, I'm not 100% on this, so my current value may be wrong...
    "I'm a dick!"
    "I must seek knowledge and it's bastard son truth" - The State

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    • #3
      Originally posted by migel628
      I'm not 100% on this, but you may be better off powering both hubs. I know the USB port supplies something like 500mA of current, so you figure that current will now be shared among 4 devices. If your devices can deal w/ 125mA each (500mA/4), then you'll be fine.

      As I said, I'm not 100% on this, so my current value may be wrong...

      USB carries 500mA on the line.
      Cheap Laptop, great for Carputer!

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      • #4
        welp... i'm not the sharpest knive on the shelf when it comes to this stuff... so i'm not quite sure if the answer to my question is "yes you will be fine or not"

        i figured for the DVD... i'd be running the power back to my PSU so it shouldn't be sucking up all this juice from USB... the webcam on the other hand is a different story.

        How would i power the USB hub in a car? From the PSU as well?

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        • #5
          Originally posted by ummagawd
          anways... i plan to run a non-powered 4 port hub to the front of the car (PC is in trunk) and hook up (DVD rom, keyboard, flash drive, touch screen)
          DVD's usually require lots of power. The best I've seen still needs 2 fully powered (500mA) USB lines.
          Progress: 80% - Permanent install left.
          Motion LS800 Tablet PC and dock.
          Vista, Bu-535 GPS, RoadRunner, MPT2006.

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          • #6
            Originally posted by ummagawd
            welp... i'm not the sharpest knive on the shelf when it comes to this stuff... so i'm not quite sure if the answer to my question is "yes you will be fine or not"

            i figured for the DVD... i'd be running the power back to my PSU so it shouldn't be sucking up all this juice from USB... the webcam on the other hand is a different story.

            How would i power the USB hub in a car? From the PSU as well?

            1) The only way to know for sure if your setup without a powered hub is feasible is to try it.

            2) you could power the hub off the 5V line from the PSU, or get/build a 12V->5V converter. There are cigarette adapter to USB chargers (for pda's and phones), which carry 5V, and there are plans for a PCB converter around this forum, you just gotta search for that.
            Cheap Laptop, great for Carputer!

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            • #7
              my experience with logitech cams has been that non powered usb hubs won't power them....your mileage may vary....
              Kevin

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              • #8
                Originally posted by jusatry
                1) The only way to know for sure if your setup without a powered hub is feasible is to try it.
                The OS will tell you if each device claims to be 100mA or 500mA. An unpowered hub can only run 4 100mA devices since it counts as a 100mA device itself.
                Progress: 80% - Permanent install left.
                Motion LS800 Tablet PC and dock.
                Vista, Bu-535 GPS, RoadRunner, MPT2006.

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                • #9
                  Originally posted by Arathranar
                  The OS will tell you if each device claims to be 100mA or 500mA. An unpowered hub can only run 4 100mA devices since it counts as a 100mA device itself.

                  Where in Windows 2000 or XP can you find out power consumption of a USB device?
                  Cheap Laptop, great for Carputer!

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                  • #10
                    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.

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                    • #11
                      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?

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                      • #12
                        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?
                        Cheap Laptop, great for Carputer!

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

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                          • #14
                            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.

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                            • #15
                              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.

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