AM335x USB babble

Hattie Spetla

Other Parts Discussed in Thread: AM3358

Hello,

We are using a AM3358 running Linux 4.1.6. We've also tested with 3.12.

On both of these builds we are experiencing intermittent babble on enable of a specific USB device on USB0. This happens whether we enable the USB peripheral on startup or after startup. We are able to successfully connect to a hub on USB1.

This device operates correctly with other systems. It also exhibits no problems once successfully enabled.

It can sometimes take 10 or 15 retries to enable the peripheral. Is this expected behavior?

We can provide usbmon logs if this would be helpful.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

I will forward this to the USB experts.

0 -DK- over 9 years ago

TI__Mastermind 27890 points

Hello Hattie,

Please describe the problem peripheral.
How is the USB0_ID pin connected/terminated on your board?
How much capacitance is present on USB0_VBUS line?
Did you follow the recommendations for USB contained in our High Speed Layout Guidelines doc?

0 Hattie Spetla over 9 years ago in reply to -DK-

Intellectual 335 points

1. It's a BTLE USB Full Speed dongle based on a BT800 from Laird.

2. We see the issue whether the USB0_ID pin is left floating or pulled to GND.

3. 150uF

4. Yes. The traces are routed differentially and observe high speed layout guidelines. We see the same issue on dev hardware in addition to our own hardware, so we do not think this is isolated to the layout. We are also looking at the signal integrity here. So far we have not see noise or other issues.

0 -DK- over 9 years ago in reply to Hattie Spetla

TI__Mastermind 27890 points

Wireless dongles, especially those transmitting in the 2.4G spectrum, are notorious for causing interference on unshielded USB interfaces. This interference could certainly result in babble.

Do you see issues with devices other than this particular dongle?
What percentage of your boards exhibit this issue?

Please post your terminal logs.

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AM335x USB babble