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USB on K20D50 (versus D75)

Question asked by Richard Sabourin on Sep 19, 2014
Latest reply on Sep 22, 2014 by Richard Sabourin

Hi folks, looking for a little advice:

We have a design based on K20D50 and the 4.1.1 bare metal USB stack implementing the CDC class. The device works fine when connected to a full-speed hub (built into my Dell keyboard), but doesn't enumerate in other places, such as the hi-speed ports on my laptop.

The K20D75 tower board, where we started development, works fine. The only relevant code changes are clocking (8 Mhz crystal PEE mode), and fixing the driver to match the syntax in the MK20D5.h file (i.e., USB0_ISTAT to USB0->ISTAT).

 

Anybody have any suggestions? Does it sound like it could be a noise or clock jitter issue?

 

Thanks!

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