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Usb (5): miscallnous USB topics
Usb (5): miscallnous USB topics

Hello,

1)

I got an answer, in usb-devel-group, to my question regarding
the benefits in hardware of OHCI against UHCI (Intel Host Controller)

The question was . to remind you:

"In drivers/usb/host/Kconfig, (linux 2.6.7) they say:

"The Open Host Controller Interface (OHCI) is a standard for accessing
USB 1.1 host controller hardware. It does more in hardware than Intel's
UHCI specification."

What does ot do more in hardware than Intel's
UHCI specification ?"

And the answe I got from David Brownell was:

"One example: sending a 4 KB buffer takes one TD with OHCI,
covering 64+ packets; with UHCI, each packet takes one TD.

Another: OHCI has separate schedules for control, bulk,
and periodic transfers. UHCI has just one."

2) USB tools:

While working with USB subsystem, I found the following tools helpful:

1) USBVIEW:
A GTK+ 1.2-based tool written by Greg Kroach Hartman.

see http://www.kroah.com/linux-usb/

Enables you to see the cahracteristics of the USB devices.

This tool displays the topography of the devices that
are plugged into the USB bus on a Linux machine.
while plugging and unplugging the USB device, this display
is updated and refreshed in real time.

The source code is available.

2) http://usbsnoop.sourceforge.net

This is somekind of a USB sniffer; runs only on Windows.

I also encountered a Project of some student from Scotland who
began developinh a Java based USB sniffer , but it seem to me
that he abondoned it.

3) Interesting USB links:

The GNU/Linux "usbnet" Driver - David Brownell
on http://www.linux-usb.org/usbnet

libusb on http://libusb.sourceforge.net

The libusb project aim is to create a library for use by user level
applications to access USB devices regardless of OS.
There is an article in linuxjournal by Greg Kroach Hartman (02/11/2004)
in which he demonstrates use of the libusb:
see http://www.linuxjournal.com/article/7795

Cheers,
RRX

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