Re: Charging iPod / Listening to music

Richard Lyons wrote:
On Wed, Oct 31, 2007 at 08:41:38AM -0400, Douglas A. Tutty wrote:

On Tue, Oct 30, 2007 at 06:14:49PM -0600, Nate Duehr wrote:
On Oct 30, 2007, at 4:01 PM, Mathieu Malaterre wrote:
It works, I can listen to music again, but even if the cable is
pluged it does not seems to be charging...
That makes sense. USB devices have to "request" how much power-draw they want to pull from the host. If you kill the "stuff" that talks to USB devices, they can't request power.
Then how does my USB light get power; surely it doesn't "request" enough
power to run an LED? I can also charge my Palm with the computer off;
there's nothing running to receive any "request".

Oh, that is interesting. Only yesterday I noticed that (at least on
this laptop) the usb is dead when the computer is off. Plugging in the
mp3 player, for example, (or mobile phone charger) has no effect, even
if the power lead to the portable is connected. Only when I start the
computer up does the usb go live. I wonder if this is simply the normal
arrangement for laptops?

It changes by laptop and chipset manufacturer for the USB host chipset and how they designed the power sub-systems.

I have seen one laptop that leaves the USB ports on in "sleep" mode, but never in "off" mode. I think it was the work IBM/Lenovo, but don't remember.

My Mac turns 'em off in sleep, if I remember correctly. Don't remember what the old eMachine USB 1.0 machine does... and then there's the desktops... they're all over the place.

Nate


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