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Original question:

AM2612: How to detect Host without VBUS pin

AM2612: VBUS detection process at the inside of AM261x

Hideaki Matsumoto
Genius 9070 points
Part Number: AM2612

Tool/software:

Hi,

The customer would like to confirm a little more. Could you help to answer their question below ?

 

There are following descriptions at the chapter 6.1.3.2.8 USB Global Configuration in the TRM.

According to the above red underlined sentences, it seems to be monitoring VBUS voltage in spite of no VBUS pin.

What does “between 4.4V and 4.75V” mean ? This device cannot treat such high voltage more than 4.0V, right ?

Could you explain this ?

or is the above mechanism disabled on AM261x ?

 

Thanks and regards,

Hideaki

  • +1
    TI__Expert 4940 points

    I am terribly sorry about the lack of reply here,

    The original owner for the USB peripheral on AM261x left TI earlier this year, and unfortunately there are areas where the documentation is confusing. 

    Yes, in a standard USB controller, the CONTROL_USBOTGHS.VBUSVALID bit would be set or cleared based on a VBUS valid line. However, since the USB controller within AM261x is powered internally and does not implement a VBUS pin, it is up to application software to set and clear the VBUSVALID bitfield.

    I am filing a request to have this updated within the TRM to clear up the confusion.

    Regards,

    Susan