Explain this one, techies!

Discussion in 'Mac Accessories' started by chaos86, Feb 24, 2009.

  1. chaos86 macrumors 65816


    Sep 11, 2003
    Here's my setup:
    Unibody Macbook Pro connected to 4-port bus-powered USB hub. Plugged into the hub is a Griffin Powermate, a Logitech Marble Mouse, an EyeTV Hybrid, and an iPhone Dock.

    The problem:
    When I get home and plug the Macbook Pro into the hub, the devices don't connect because they don't have enough power. I know this because the powermate's light pulses as it does when the computer is asleep, the EyeTV software doesn't start, the mouse doesn't work.

    The solution I've found:
    Put the iPhone in it's dock. Instantly, the other devices connect. Take it out and they're still connected. Unplug the hub, plug it back in, and they reconnect fine. But if the computer has been disconnected for a while, then it needs the phone before the other devices work.

    Weird huh?
  2. harry454 macrumors 6502

    Sep 13, 2007
    I think it has to do with the new usb things with the new unibodies, like how you cant jailbreak new iphones form a unibody cause of the usb driver
  3. michaelsviews macrumors 65816

    Sep 25, 2007
    New England
    Hard to put into words but more than likely the iPhone sends / communicates in a better stronger form than the other devices, also the iPhone has more demand of power then the other devices your using .

    My 2 cents
  4. Sesshi macrumors G3


    Jun 3, 2006
    One Nation Under Gordon
    It depends on whether the hub is passing along the current demand to the Mac, and what irregularities arise from that. Technically speaking it seems you're demanding more than USB would normally deliver out of the unpowered hub.

    For trouble free use I'd recommend a powered hub.
  5. Schtumple macrumors 601


    Jun 13, 2007
    Same, I dislike using un-powered hubs, unless you're only plugging in little things like digital cameras or iPods/Phones, they can be more hassle than they're worth...

    I've bought countless "USB 2.0" hubs that I bring home, and because they didn't come with the AC power adapter, only transmit at USB 1.1, kind of false advertising eh? Be nice to know before I actually buy it...
  6. dmmcintyre3 macrumors 68020

    Mar 4, 2007
    Get a powered hub. I lost the power adapter for my powered hub and I now have to plug my keyboard directly into my PowerBook to get the usb ports to provide enough power for my flash drive even
  7. Tomorrow macrumors 604


    Mar 2, 2008
    Always a day away
    +1. The iPhone has a battery which your MB is trying to charge. It might not sound like much, but it makes a pretty big difference on a non-powered hub.
  8. harry454 macrumors 6502

    Sep 13, 2007
  9. skorpien macrumors 68020

    Jan 14, 2008
    I have no technical knowledge of this, but I'm willing to give this a guess at any rate. It seems to me that when your MacBook Pro detects that an iPhone is connected, it passes more power through the USB port in order to be able to charge the iPhone's battery. This is in turn transmitted to the devices connected to the hub, thereby powering them without having to plug in an external power source. It also seems that the MBP doesn't revert back to the original power output for the USB port immediately after you unplug your iPhone, but given enough time without any USB devices attached it will (explaining why you need to reattach the iPhone). What I'd be interested in is if the other devices will eventually disconnect if you just unplug the iPhone from the hub and leave the rest connected to the computer (ie, whether the MBP continues supplying the higher rate of power to the devices when the iPhone is disconnected from the hub).

Share This Page