Hi Jim
I am powering my TS-7260 using an unregulated 12V 2A power supply as
found in a burglar alarm enclosure (BTW, because these things are
manufactured in huge volumes, this a very inexpensive way
to box a project - solid gauge metalwork and an enclosed power supply
for very few $).
Being an unregulated supply, I am therefore relying on the on-board
requlator to perform the necessary magic.
Of course, this is where the problem might lie, as the 12V is regulated
down to 3.3V, whence charge pump circuitry is used to create the 5V
rail. It is quite likely that this latter circuitry hasn't got the
necessary "oomph" to handle the initial current spike which the USB
hard drive requires.
It's a shame that the board didn't do serial regulation instead (input
regulated down to 5V regulated down to 3.3V) as this would likely have
overcome the problem.
Anyhoo, since my drive can be powered externally, I will follow
Markus's suggestion and buy a cheap 5V power supply.
However, this leaves me with a new problem :-(
By default, the USB ports are enabled to receive the internally
generated 5V supply - which I neither need nor indeed want. This can
of course, be turned off by setting the appropriate bit in register
0x1200_0000 using the poke8 command. The only problem is that this
will be done late in the boot cycle, whereas I need it to be in effect at
power up - otherwise the power supply electronics will get their
knickers in a twist!
So, my problem has now morphed to this: How can the "USB 5V Power" bit
in register 0x1200_0000 be made to default to "off" at power up,
rather than "on"
as at present?
All suggestions (as usual) gratefully received.
Cheers,
Philip
--- In Jim Jackson <> wrote:
>
>
>
>
> On Fri, 19 Jan 2007, tyerslockandblock wrote:
>
> > Hi Markus
> >
> > You are absolutely right, my drive is 2.5" and NOT 3.5" as I wrote; I
> > really should re-read my postings carefully before hitting the send
> > button :-(
> >
> > Anyway, being a 2.5" drive, it does in fact require a 5V DC supply -
> > which can be USB-supplied.
>
> Yes but you have not mentioned at any point what power supply you are
> using to supply the 5V for the TS board. If that is insufficient to
> provide the initial surge (which can be quite a bit more than the
> power drawn after start up) there will be problems.
>
> > I take on board your comments about higher initial power consumption,
> > but this drive has been used succesfully for over a year while
> > attached to a hacked and frequently re-booted Linksys NSLU-2 (which I
> > used as my original prototype platform), so I am somewhat surprised
> > that it would hiccup on my TS-7260.
> >
> > Your suggestion that I should perhaps invest in a powered USB hub is a
> > good one - and may well be the route I need to follow - but perhaps
> > someone out there has an alternate suggestion which won't cost me
> > money ;-)
> >
> > Cheers,
> > Philip
> >
> >
> >
> > --- In Markus Peuhkuri <puhuri@> wrote:
> > >
> > > tyerslockandblock wrote:
> > > > I have a USB-powered 3.5" disk drive which I wish to use during
> > > > application development. This device requires a 5V power
supply, which
> > >
> > > Are you sure that it is 3.5" and needs only 5V? AFAIK, all 3.5"
drives
> > > need both 5V and 12V and draw more current than USB can supply.
Even if
> > > your drive would have 100% efficient 5V to 12 V converter, your
USB port
> > > should supply on average about 2 A of current (10W) (USB max is
0,5 A)
> > > and at startup a drive can take three or four times of that.
> > >
> > > However, an 2.5" drive is just in USB specs on average (like 2.2
W) and
> > > needs only 5V, but you may have problems at startup, as even a slow
> > > drive can take more than 1.1 A at start.
> > >
> > > For example, I have problems with my laptop (Dell D600) and 2.5" USB
> > > drive. I need to use USB hub with external power or then PC
Card with
> > > USB connectors to supply enough current to get it running.
There is a
> > > windows patch by Dell to fix it, it just causes windows to ignore
> > > overcurrent condition -- could patch Linux to do the same, but I'll
> > > prefer data integrity :-).
> > >
> > > Try with USB hub with power input.
> > >
> > > t. Markus
> > >
> >
> >
>
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