Re: USB host controllers

R. McCarty wrote:
> Each "Physical" Port ( Socket ) works through a transceiver that
> has interconnections between the Enhanced Controller and the
> standard controllers. So all USB 2 devices will show up in the
> "Advanced" (TAB) of the Enhanced Controller. Any USB1/1.1
> Devices will appear in the Host Controller properties.
>
> So you can't really map USB2.0 devices to a physical port, they
> all route to the same Host Controller.
>
> But you can do that by using USB1 (Full Speed) devices since
> they'll appear on their respective Host Controllers Advanced
> details box.
>
> My Intel 865 motherboard has 8 Ports and in Device Manager
> I've got 1 Enhanced and 4 Low speed Controllers.
>
> A little bit confusing, isn't it

Somewhat, but manageable. The USB2/EHCI part is simple enough. What
complicates things a bit is that there are multiple "logical" ports
associated with each controller. As you point out, you have 8 physical
ports but only 4+1 controllers. I think, though I haven't actually
counted, that the total number of ports showing under all controllers
exceeds the number of physical ports I have, so what's the
relationship?

This subject is related to my feeble attempt to distribute the activity
of my USB devices across ports (as shown in Device Manager). I have a
USB2 TV tuner, whose power requirements exceed the single port "limit"
of 500ma (it is in fact supplied with a second USB connection just to
obtain the additional power, though I don't need to use it on my
laptop), plus a USB2 DVD drive, plus a USB2 HDD and occasionally a
second HDD. All these together surely exceed the 500ma that a USB2 port
is expected to supply, and yet it works, without even using the second
connection on my tuner. SO I can't help but wonder what the 500ma
figure actually Apart from the power issues, I was thinking that it
would be a good idea for more ports to get a piece of the action simply
for reasons of reduced contention. I have no idea how to manage this.

.

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