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I a working on a project around the STM32H7 (Nucleo STM32H743ZI2) on which I am using the user USB to communicate through CDC interface. Everything is working fine, however, I just noticed that this User USB port is not powering the board. I am pretty sure initially it was, but well it's no longer the case.

what is the CubeMX settings to enable this user USB port to power the board? The goal is to use this USB port to connect to the PC communicating with the board (and not the STLINK USB).

right now I have the USB_OTG_FS set to Device_Only, activate_VBUS set to VBUS sensing and activate_SOF is enabled.

thanks!

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  • \$\begingroup\$ nvm, not possible per documentation. oh well \$\endgroup\$
    – zytra
    Commented Jul 20, 2020 at 23:55
  • \$\begingroup\$ If you think this is supposed to be supported, study the published board schematics until you understand how it is supposed to work. \$\endgroup\$
    – Chris Stratton
    Commented Jul 21, 2020 at 0:26
  • \$\begingroup\$ On the STM32F4 Discovery board, I usually use a jumper wire to bridge the user USB VBUS to the 5V -> 3V regulator. Not sure if that's possible on your board. \$\endgroup\$
    – Felix S
    Commented Jul 21, 2020 at 13:07
  • \$\begingroup\$ I read the doc again and it clearly says that the User USB cannot be used to power the board \$\endgroup\$
    – zytra
    Commented Jul 22, 2020 at 16:13
  • \$\begingroup\$ Please provide links to relevant data sheets plus section and page numbers so others can benefit/. Additionally, saying WHY this is the case (which may require you to look at schematics, would be informative. \$\endgroup\$
    – Russell McMahon ♦
    Commented Aug 4, 2020 at 6:39

1 Answer 1

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I read the Nucleo doc for my H743ZI2 again and it clearly says that the User USB cannot be used to power the board.

THis is more of a limitation of the development boards rather than a limitation of the USB OTG itself.

Thanks

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  • \$\begingroup\$ Please provide links to relevant data sheets plus section and page numbers so others can benefit/. Additionally, saying WHY this is the case (which may require you to look at schematics, would be informative. This also has the advantage of making the answer useful enough to be not much more than a comment. \$\endgroup\$
    – Russell McMahon ♦
    Commented Aug 4, 2020 at 6:39
  • \$\begingroup\$ I missed this comment. ugh sorry. Please refer to chapter 6.6.6 of the Nucleo User Manual ref. UM2407 (MB1364) page 27/50. Quote: "Warning: USB Micro-AB connector (CN13) cannot power the Nucleo- 144 board. To avoid damaging the STM32H7, it is mandatory to power the Nucleo-144 before connecting a USB cable on CN13. Otherwise, there is a risk of current injection on STM32H7 I/Os." \$\endgroup\$
    – zytra
    Commented Sep 30, 2020 at 2:33

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