Re: USB port idiosynchracies

On Mar 18, 10:25 am, D Yuniskis <not.going.to...@xxxxxxxx> wrote:
Hi,

I've played with two appliances in the past week
that each imposed what *seem* to be arbitrary
restrictions on the use of their USB ports.

The first, an NSLU2, only allows a "thumb drive"
to be used on one (particular) of the two ports
("real disks" can be used on either/both).

The second, a LinkStation, also allows only one
thumb drive (plus one printer) -- though it doesn't
force the thumb drive to a *particular* port.

Peeking inside the NSLU2 shows power is simply not
routed to the second USB port (though it could easily
be with the addition of an unpopulated ferrite bead).

I haven't taken apart the LinkStation for fear of damaging
the case -- yet.  :>

I don't see why this arbitrary restriction.  Unless they
simply haven't the extra 2-3W (worst case) to power an
extra thumb drive??

Are there some other USB subtleties of which I am unaware?
Or, chipset problems??

--don

I'm guessing the answer is "engineering compromises".

If you have a USB2 port, you are *required* to be able to source a
full amp to it (worst case = 5W), or turn it off if it over-currents.
Either of those costs money. 99% of the world is happy connecting one
thumb drive, or an externally powered HDD. So there you have it.

RK
.

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