AM4376: USB2.0 FS signal quality test

g.f.

Part Number: AM4376

Hi,

I have a question about AM437x USB Host Mode.

My customer want to test the "USB2.0 Full Speed Signal Quality".
Is it available to test the "USB2.0 Full Speed Signal Quality" by
using USB Test Mode(Host Mode) which are written in the following TI Wiki?
processors.wiki.ti.com/.../USB_Test_Mode_on_DWC3

If yes, what value should be set to which register address of AM437x?

best regards,
g.f.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

Please follow processors.wiki.ti.com/.../Linux_Core_DWC3_User's_Guide

0 g.f. over 8 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Thank you for the reply.

From USB2.0 specification, my understanding is that Test Mode is mode for High Speed only and not for Full-speed
But I'm not sure, so that is why I'm asking in this post.
Sorry, but I can't find this information from wiki page which you attached.

To test the "USB Full speed Signal Quality", AM437x USB just need to be initialize to Host mode and Full Speed,
and then sending some command(?) from oscilloscope, is it correct?

best regards,
g.f.

0 Biser Gatchev-XID over 8 years ago in reply to g.f.

TI__Guru**** 393215 points

I have notified the USB experts. They will comment here.

0 g.f. over 8 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Thank you so much for your support.

best regards,
g.f.

0 -DK- over 8 years ago

TI__Mastermind 27890 points

For both FS and LS testing, no specific register changes are required as the dedicated test mode (TEST_PACKET) for USB signal quality wasn't introduced until the 2.0 revision of the USB Specification.

Because the High-Speed test specification is much more stringent that that of the Low-Speed and Full-Speed tests, today only the High-Speed test is commonly used to quantify signal quality performance on new designs.

Please refer to the USB-IF test specification (http://www.usb.org/developers/compliance/electrical_tests/) for details on performing the LS and FS signal quality tests if you still wish to perform these tests.

0 g.f. over 8 years ago in reply to -DK-

Guru 15520 points

Hi DK,

Thank you for the reply.

I understood that TEST MODE is only for High-Speed.

For FS testing, there are Droop/Drop test which test the VBUS voltage level(minmum 4.4V to max 5.25V)
and Downstream Signal Quality test.
USB Host(FS) will issue SOF(Start of Frame) every 1ms on D+/D- line automatically,
so that user capture the D+/D- Line by oscilloscope and check the eyepattern and
check either it pass the signal quality test or not, is it correct?

best regards,
g.f.

0 -DK- over 8 years ago in reply to g.f.

TI__Mastermind 27890 points

g.f.,
You are correct. Please keep in mind that a FS device must be connected to the Host and enumerated in order for the Host to begin sending the required SOF packets. The USB-IF test specification I linked earlier in this thread has more details.

0 g.f. over 8 years ago in reply to -DK-

Guru 15520 points

Hi DK,

Thank you so much.
I understood.

best regards,
g.f.

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AM4376: USB2.0 FS signal quality test