AM3352 USB lock-up

Brian Antheunisse

Other Parts Discussed in Thread: AM3352

Hi Team,

I have a customer using the AM3352 and is seeing a lock-up on the USB port when using it in host mode after connecting a USB device. I looked through the Sitara Schematic Checklist and they have tried everything there with no results. Eventually they added a USB signal switch between the AM3352 USB lines and the connector which fixed the problem.

Send me a note and I can share schematics privately.

Thanks,

Brian

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

What software are they using?

0 Brian Antheunisse over 9 years ago in reply to Biser Gatchev-XID

TI__Expert 5305 points

Linux (version 4.4.x) with custom applications on top of it.

0 Biser Gatchev-XID over 8 years ago in reply to Brian Antheunisse

TI__Guru**** 393215 points

Thanks. The USB experts have been notified. They will respond here.

0 -DK- over 8 years ago

TI__Mastermind 27890 points

Brian,
What do you mean by "signal switch"? A signal mux?
Do all USB devices fail in the same manner?
What types/speeds of devices have been tried?

Please send the schematic to Biser.
Please provide a terminal log with the error.

0 Brian Antheunisse over 8 years ago in reply to -DK-

TI__Expert 5305 points

check the thread tracker for schematics, and you'll see the signal switch used there.

All devices fail in the same manner. Not sure about speeds, but I believe the USB lines lock up regardless of the datarate.

Thanks,

Brian

0 Brian Antheunisse over 8 years ago in reply to Brian Antheunisse

TI__Expert 5305 points

also, there is not any log of the error, since the issue is that the USB port stops receiving data. It does not report any failure since it does not know anything is trying to talk to it.

Thanks,
Brian

0 -DK- over 8 years ago in reply to Brian Antheunisse

TI__Mastermind 27890 points

They changed a lot more than just the signal switch...

1) The ESD components are different. These have a direct impact on signal integrity.
2) On the "bad" design, the USB_ID pin is not correctly terminated. This was rectified on the "good" board by connecting USB_ID directly to GND for Host mode operation.
3) I can't tell from the limited schematic how power is delivered to the USB Device, but it appears that some capacitance was added to the "good" board via P5V input to D1. A USB Host is required to provide >=120uF on VBUS.
4) There look to be significant layout changes between the boards. This too will directly affect signal integrity.

I'll also note that they added series resistors to the USB DP/DM pair. These are not permitted. Please review the AM335x Schematic Review Checklist as well as SPRAAR7 for guidelines.

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AM3352 USB lock-up