AM4378: VBUS control in Linux

Hitoshi Sugawara

Part Number: AM4378
Other Parts Discussed in Thread: AM3351,

Hi Experts,

Could you please let me know how to make VBUS for USB ON and OFF through controlling DRVVBUS by Linux.

According to the e2e https://e2e.ti.com/support/processors/f/791/t/730429, it says that it is clear that if the VBUS voltage drops below 4.4V for more than 100ms, the USB subsystem detects this as over-current (fault) condition. In this case, does it also de-assert the DRVVBUS signal (high to low).
Where is the document which describes this behavior?

Thank you for your help.
Best regards,

Hitoshi

over 4 years ago

0 Bin Liu over 4 years ago

TI__Guru*** 127206 points

Hi Hitoshi-san,

The e2e thread you referred is for device AM3351, which uses a different USB controller from that on AM4378. So the information in the referred e2e thread might not be applicable to AM4378.

Can you please describe what is the issue you are trying to solve? or what question do you have regarding VBUS vs DRVVBUS?

0 Hitoshi Sugawara over 4 years ago in reply to Bin Liu

TI__Mastermind 18660 points

Hi Bin,

An external USB product is connected the system.
When it fails USB connection, I would like to VBUS OFF and ON to recover the condition.

Best regards,
Hitoshi

0 Bin Liu over 4 years ago in reply to Hitoshi Sugawara

TI__Guru*** 127206 points

Which Processor SDK version do you use?

Have you checked the VBUS is ON prior attaching the USB device? and the VBUS is OFF after attached the USB device?

Please post the USB portion of the schematics.

0 Bin Liu over 4 years ago in reply to Hitoshi Sugawara

TI__Guru*** 127206 points

Hi, I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out). thanks.

0 Hitoshi Sugawara over 4 years ago in reply to Bin Liu

TI__Mastermind 18660 points

Hi Bin,

I am sorry my absence.
Let me check it and start communication with you from here again.

will come back soon.
Thank you.
Best regards,

Hitoshi

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AM4378: VBUS control in Linux