• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 98 subscribers
  • Views 495 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM1808 with USB OTG as a device

Filosofi
Intellectual 925 points

Hi all,

I know it is possible to force the USB2.0 controller to operate only in device mode by programming USB0OTGMODE=2h in the register SYSCFG[CFGCHIP2].

The urgent question is, does it suffice irrespective to the state of USB0_VBUS input ?

Or it is absolutely required to apply a 5V voltage on USB0_VBUS ?

Best Regards,

Gabriele Filosofi

  • 0
    TI__Genius 14545 points

    Filosofi said:
    Or it is absolutely required to apply a 5V voltage on USB0_VBUS ?

       It's better to use this pin to detect the presence of a USB Host when operating as a USB Device. You can disable this sense detection in the SYSCFG module, and not use the VBUS pin, however the firmware will have no way of knowing if a USB Host is present unless you can implement it with some other HW logic. Also, if there are any errors with regards to the VBUS voltage level being valid, you will loose auto-detection of this by the PHY.

  • 0 in reply to dabuan
    Intellectual 925 points

    Drew,

    I cannot directly connect this pin to the VBUS terminal of the micro-B connector, because there is an isolator device in between ! 

    It may be a solution to tie this pin to the 5V system rail ?

    Gabriele Filosofi

     

  • 0 in reply to Filosofi
    TI__Genius 14545 points

    Filosofi said:
    It may be a solution to tie this pin to the 5V system rail ?

     

    This should be fine as long as the 5V rail is only powered when all the other device rails are powered.

  • 0 in reply to dabuan
    Intellectual 925 points

    Yes it is. Thanks a lot.

    Gabriele