stm32F411 and Vusb

[leogarberoglio]

Posted on October 02, 2015 at 13:41

Hi, I'm trying to understand a Note from Reference Manual page 665. It state:

''

The V

BUS

pin can be freed by disabling the V

BUS

sensing option. This is done by setting the

NOVBUSSENS bit in the OTG_FS_GCCFG register. In this case the V

BUS

is considered

internally to be always at V

BUS

valid level (5 V).''

It does mean that I can leave  PA9 pin with no conection (Vusb) to anithing and make USB device to work ok? just configuring NOVBUSSENS bit? Thank!

[Nesrine M_O]

Posted on October 02, 2015 at 15:58

Hi elgarbe,

Yes, this is the purpose of the NOVBUSSENS bit - if you know that the VBUS is present (for example if you are bus-powered), you can use this bit to free the PA9 -Syrine-

[leogarberoglio]

Posted on October 02, 2015 at 16:15

and what happend if my board is dual powered, USB (if it is connected) and external power supply? do I have to put 5V on PA9?