USB 1.1 vs. 2.0 and USBTMC

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Hi group-

I'm hoping some USB knowledgeable persons can help with this USBTMC
(Test & Measurement Class) question...

USBTMC prescribes two descriptors that are supported under 2.0 but not
1.1.  They are the device qualifier and other-speed configuration
descriptors.  Neither have anything to do with USBTMC.  Instead they
seem to exist for 2.0 high-speed support.

Does anyone know if it's a violation of the the USBTMC standard to
implement USBTMC under the 1.1 standard thus forgoing the two extra 2.0
descriptors?

JJS


Re: USB 1.1 vs. 2.0 and USBTMC
Quoted text here. Click to load it

This is a very wide-spread misunderstanding, but complying to USB 2.0 does
not imply high-speed.
I have made many USB 2.0 compliant full-speed devices, implemented using
existing chips originally designed for USB 1.1.

Set bcdUSB to 0x200, and stall when the host ask for the device qualifier.
Thats all.
Remember to test your implementation with usbcv.

Leo Havm°ller.



Site Timeline