Re: Working umass SD card readers.

From: Bernd Walter <ticso_at_cicely12.cicely.de>
Date: Sat, 18 Oct 2003 20:14:02 +0200
On Sat, Oct 18, 2003 at 03:16:33PM +0200, Andreas Klemm wrote:
> On Wed, Oct 15, 2003 at 05:29:08PM -0700, Michael wrote:
> > Just to let everyone know, I've been using a Lexar Media JumpDrive Trio
> > (picked up at Target for $19.95) and it works.
> > 
> > Oct 11 11:58:41 whatever kernel: umass0: Lexar Media JumpDrive Trio, rev
> > 2.00/1.25, addr 2
> > Oct 11 11:58:45 whatever kernel: GEOM: create disk da0 dp=0xc62d7c50
> > Oct 11 11:58:45 whatever kernel: da0 at umass-sim0 bus 0 target 0 lun 0
> > Oct 11 11:58:45 whatever kernel: da0: <Generic STORAGE DEVICE 0125>
> > Removable Direct Access SCSI-0 device
> > Oct 11 11:58:45 whatever kernel: da0: 1.000MB/s transfers
> > Oct 11 11:58:45 whatever kernel: da0: 60MB (124160 512 byte sectors: 64H
> > 32S/T 60C)
> 
> Does it work on USB 1.1 ?
> 
> This page tells:
> 	Designed for use with USB 2.0
> 
> http://www.amazon.com/exec/obidos/tg/detail/-/B00008RW8L/002-9526850-1143261?v=glance
> 
> Well "designed for" certainly doesn't mean "it only runs on 2.0"
> but to be sure I'd like to ask prior buying ;-)

USB 2.0 doesn't necessarily mean high speed, but could also mean just
full speed with updated config descriptor, etc.
USB 2.0 devices are required to fall back to full speed which means
that any uhci/ohci controller is enough to just get them working with
lowered speed.
I never saw problems with this fall back.

> BTW, is there anything important to look for when buying such a reader ?
> I see in this thread, that there are devices with builtin disk and some
> without ...

That's the real problem - getting a vendor to honour umass
specification should be enough, but in reality many vendors fail on
this thing :(
Many devices should work just out of the box, but you better have the
option to return it to your dealer just in case.

-- 
B.Walter                   BWCT                http://www.bwct.de
ticso_at_bwct.de                                  info_at_bwct.de
Received on Sat Oct 18 2003 - 09:14:15 UTC

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