[Techtalk] USB hardware question

Aaron Mulder ammulder at alumni.princeton.edu
Thu Jan 10 11:10:46 EST 2002

	Many motherboard come equipped with a USB controller, but you have 
to buy and/or attach a cable to a couple ports in a bracket that fits in 
place of an expansion card on your case.  So it may be that you just need 
that cable/bracket to use the USB ports on your motherboard.  However, 
many USB mice have a little adapter to convert them to PS/2 mice, so just 
because the manual mentions USB in the "mouse" section doesn't necessarily 
mean it has USB support on the motherboard.
	Is there any way for you to tell whether FreeBSD is detecting the 
USB controller on the motherboard or the one on the expansion card (say, 
by removing the card and seeing if you get the same message)?

	As for the terminology, I'm no guru, but I think a "USB
controller" is just a chip that provides an interface to the computer.  
You generally need some sort of "hub" to plug devices into.  For the ports
on your computer, you generally see entries for the "root hub", which is
just another name for the ports on the back of your PC.  You can, of
course, attach additional "normal" USB hubs to that to handle more
	"uhci", at least on Linux, is just a category of USB controllers 
(as opposed to "ohci"), which includes those made by Intel and Via, among 
others.  I guess "usb0" is referring to one of the USB ports the 
controller provides, though again if it's a controller on the MB you may 
need the bracket to access it.
	On Linux (2.4.16), you can get some (not very friendly) output on
your USB system by running "cat /proc/bus/usb/devices".  Probably 
somewhere else on FreeBSD.


On Thu, 10 Jan 2002, Amanda Babcock wrote:
> I'm trying to set up my computer for USB and I'm confused about the 
> hardware required.
> It doesn't have any USB ports that I'm aware of, but the manual for the
> motherboard mentions USB in the part about support for a PS/2 mouse.
> Back in 98 or so I bought a no-name USB PCI card, a Kouwell KW-580, and 
> installed it but was never able to make it work (not even under Windows).
> The USB card is currently not installed, but the machine must be detecting
> the host controller on the motherboard because it shows the following
> during boot-up (this is a FreeBSD system):
> Dec 11 22:34:05 mercury /kernel: uhci0: <VIA 83C572 USB controller> port 0x6100-0x611f irq 11 at device 7.2 on pci0
> Dec 11 22:34:05 mercury /kernel: usb0: <VIA 83C572 USB controller> on uhci0
> Dec 11 22:34:05 mercury /kernel: usb0: USB revision 1.0
> (Incidentally, the motherboard manual does not show a "VIA 83C572" anywhere
> in the diagram...)
> So, my question is: do I *need* a USB card, or can I plug stuff into the 
> controller?  What's a USB controller anyway?  Am having trouble finding a 
> basic "What is USB" page out there.  Plenty of info on required drivers 
> and kernel configs for both Linux and FreeBSD, but nothing on "what the 
> heck is USB anyway".
> Amanda
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