USB and FW Ports during Deep Sleep

Discussion in 'Apple' started by pixel_a_ted, Dec 12, 2006.

  1. pixel_a_ted

    pixel_a_ted Guest

    I believe that when I connect my iPod to the FW port of my G5 it
    continues to charge when the computer goes to sleep. I recently got a
    new iPod Shuffle that uses USB. I connected it to a port on the
    computer but when the computer went to sleep the light that indicates
    charging goes out.

    So, I guess to conclude from this that the FW port continues to have
    power when the computer sleeps but not so for the USB port. I'd just
    like to get a confirmation on this and also, although I know it's not
    likely, I'm just wondering if there is a way to keep the USB port on
    during sleep.

    Thanks.
     
    pixel_a_ted, Dec 12, 2006
    #1
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  2. pixel_a_ted

    larwe Guest

    The USB specification states that the port should not supply power
    unless the machine is ready to enumerate an inserted device.

    (Many computer vendors violate this spec, by the way).
     
    larwe, Dec 12, 2006
    #2
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  3. pixel_a_ted

    john evans Guest

    I've just tested the FW port on my shut down intel mini & power is present.
     
    john evans, Dec 13, 2006
    #3
  4. pixel_a_ted

    zit Guest

    If my TiBook 800 is plugged in to the wall, then it provides FW power
    during sleep.
    Providing power while shut down is brain dead.
     
    zit, Dec 18, 2006
    #4
  5. Which particular part of the spec are you thinking of? I can't think of
    one which says that.

    When a Mac sleeps, the USB ports are put into suspend mode. Power is
    present at the port, but a device (such as an iPod) is not allowed to
    take any significant power from the port. With a little cooperation
    between the Mac and the iPod it would be possible for the iPod to
    charge while the Mac is sleeping, but its not been implimented like
    that.

    I would expect a desktop not to charge an iPod over FireWire in sleep.
    Usually a desktop's power supply is in a standby mode when the Mac is
    sleeping, its not designed to supply signifcant amounts of power, just
    enough to keep the RAM alive. (But I seem to be wrong about that.)

    Laptops are a bit different, they'll charge the iPod in sleep via
    FireWire when plugged into A/C power, but not when they're running off
    battery.
     
    Barry Twycross, Dec 19, 2006
    #5
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