Total power from USB

[Tiago Marques]

I forgot to mention that's not my case since even if I plug the two USB ends
it still can't power up.

Best regards,
Tiago

On Sat, Apr 24, 2010 at 7:42 PM, Sameer Verma <sverma at sfsu.edu> wrote:

> On Sat, Apr 24, 2010 at 4:55 PM, Tiago Marques <tiagomnm at gmail.com> wrote:
> > Hi all,
> > I've ran into something on the 1.5 B2 I have here, which I'm in doubt if
> may
> > or may not be relevant for OLPC's hardware people(it seems not), so I'm
> > reporting it anyway.
> > All three USB ports can deliver enough power to an USB 2.5" HDD, no
> problem.
> > They cannot in the following conditions:
> >  - An extra SD card is plugged in
> >  - Another USB device is plugged in one port, even one of lower power
> like a
> > flash drive. (sometimes it only takes one, sometimes it takes two, SD
> card
> > power also seems to be an issue)
> > When I try to plug in the 2.5" HDD, it doesn't have enough power to
> spindle
> > at enough speed and sits there trying to start itself.
> > When plugging in an USB device or SD card after the 2.5" HDD is already
> > working, it suffers a loss of power and enters the restarting state. This
> is
> > true if the SD card is plugged in instead(with another USB device
> present),
> > which suggests me that the power is shared.
> > No other plugged devices seem to be rendered temporarily unaccessible due
> to
> > the power failure on the high power device.
> > Best regards,
> > Tiago
> > _______________________________________________
> > Devel mailing list
> > Devel at lists.laptop.org
> > http://lists.laptop.org/listinfo/devel
> >
>
> I see a similar issue with a Lacie drive on my Dell desktop. This
> drive actually comes with a cable that has two USB cables to draw
> power from two ports. With two ports, the platter spins without any
> problem. With one port, the disk clicks on the Dell.
>
> On a XO-1 G1G1, XO-1.5 B2 and XO-1.5 C2 I am able to power the same
> drive via one port only both with a SD card and without a SD card. The
> issue may very well be the USB drive power draw. I am using a LACIE
> Design by FA Porsche http://bit.ly/9HD5uI
>
> This will be important for XS-on-XO scenarios, where we would
> piggyback the /library partition onto an external drive.
>
> cheers,
> Sameer
>
> --
> Dr. Sameer Verma, Ph.D.
> Associate Professor, Information Systems
> Director, Campus Business Solutions
> San Francisco State University
> http://verma.sfsu.edu/
> http://cbs.sfsu.edu/
> http://is.sfsu.edu/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.laptop.org/pipermail/devel/attachments/20100424/585d87dd/attachment.html>