More on USB2

On Sun, 04 Nov 2007 04:32:11 -0500, Paul <nospam@needed.com> wrote:

>gecko wrote:
>> Help me understand what is going on. Please.
>>
>> I have two machines:
>> Machine A has a total of six USB ports (connectors)
>> Machine B has a total of eight USB ports (connectors)
>>
>> I ran EVEREST on both to try to see if either machine truly had USB2.
>>
>> Everest shows 4 USB1 Controllers and 1 USB2 Controller on BOTH
>> MACHINES!
>>
>> So I presume that I indeed do have USB2 capability on both machines.
>> But which port (or ports)? And why 5 controllers for 6 (or 8) ports?
>>
>> Am I confused? You betcha.
>>
>> TIA
>>
>> G
>
>The items shown in Device Manager are not "Ports".
>They are logic blocks. They are dynamically connected
>to the Ports, as required. In other words, during
>negotiation, a Port can be run in USB 1.1 or USB 2.0
>mode, so the wiring to the logic block has to change
>on the fly.
>
>Try Figure 25 on page 223 of this document. This is easier
>than me trying to draw this in ASCII art.
>
>http://download.intel.com/design/chi...s/25251601.pdf
>
>One USB 1.1 logic block, is used on a maximum of two USB ports.
>The USB 2.0 logic block, is used by up to eight ports.
>
>This tool can give some info on speeds, but the tool won't
>explain why a device is not running at the maximum it supports.
>
>"UVCView – Diagnostic Tool for USB Video Class Hardware"
>http://www.microsoft.com/whdc/device...VCViewdwn.mspx
>
>For a USB device, the "Current Config" value tells you what
>speed the device is currently running at.
>
> Current Config Value: 0x01 -> Device Bus Speed: Full (i.e. USB 1.1)
>
>The "bcdUSB" tells you what standards the plugged in device claims
>to support. This is basically a declaration of their max possible
>speed, in a sense. So "Current Config" cannot be greater than "bcdUSB".
>
>Values: 0100, 0110, and 0200, for USB 1.0, USB 1.1, and USB 2.0 standards.
>Example:
>
> bcdUSB: 0x0110
>
>Reference - http://www.beyondlogic.org/usbnutshell/usb5.htm
>
>What is still missing, is any info about why a device won't run at
>the full speed. I.e. If "Current Config" is less than bcdUSB, and
>yet there is an "Enhanced" section (USB2 capable logic block) showing
>in UVCView, it doesn't explain why the driver is not moving the device
>to the USB2 section.
>
>At least in some cases, this can be explained by poor signal quality
>on the computer case front USB ports. Signal quality is generally
>excellent on the motherboard rear USB Ports, as the signals there
>travel on the PCB - the engineer who designs the board is careful
>to set the impedance correctly for such signals. But the computer
>case wiring is done by careless people, which is why some of it
>is busted with respect to USB2 operation. Antec was noted for this,
>but has finally fixed it after a couple years of customer complaints.
>
> Paul
Thanks all

I downloaded and ran UVCView on both machines. It shows 8 ports even
though one machine only has 6. In any case, I stuck a Memory Stick
into each of the USB ports and UVCView showed it as USB-2 in all
cases. Ergo, I guess I can conclude that all of my USB ports on both
machines can handle USB2.
G