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Linux/AM5728: USB2 test patterns through Hub

Part Number: AM5728

Tool/software: Linux

Hi all. This could be user error, meaning I just need to write to a couple of registers, or it could be something wrong with my design. I'll paste a screenshot of the schematic below.

Basics: I connected USB2 to a TUSB4041, which drives three USB mini-B jacks. Non-standard, I know, but the system has space constraints. It basically works - we can connect thumb drives to the jacks, transfer data, etc. I want to do some testing to check the eye diagram, jitter, etc. At the test facility, we couldn't get the test patterns to appear at the jacks. I can get the 5728 USB port into test mode using the debugger as directed here: http://processors.wiki.ti.com/index.php/Linux_Core_DWC3_User's_Guide#USB_2.0_Test_Modes. When queried, the processor then reports it's in the mode commanded. However, we don't see the test patterns at any of the jacks. Do we need to do something to tell the processor to route the test pattern to a particular 4041 output?

If I recall correctly, the 5728 did not detect that the test fixture was plugged into a jack. I feel like that's part of the problem, but I don't know why we can detect a thumb drive but not detect the tester. Thoughts?

This might need to be referred to USB experts.


Many thanks!


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