STM32H743XGH6 USB VBUS

[NiM]

I want to use port PA9 of STM32H743XGH6 as “FS_VBUS”.

In this case, which number should I put in the target register for the alternate function?

I understand that if I use CubeMX, it will set it automatically.

[TDK]

It does not correspond to an AF. It is an "additional function" which will be active when it's configured within the USB registers. It hijacks the pin.

Probably from the VBDEN bit:

 

Kind of like the PH0/PH1 pins--they have HSE functionality regardless of the GPIO configuration when HSE is enabled.

[FBL]

Hi @NiM 

Since VBUS sensing is defined as additional function, it should be left at its default state (analog mode). So, you should configure PA9 as an input with no pull-up or pull-down resistors, and ensure it is in analog mode.

[TDK]

@FBL 

> Since VBUS sensing is defined as additional function, it should be left at its default state (analog floating input).

Is this documented anywhere? Where? I've looked, maybe I've missed it.

[FBL]

Hi @TDK 

I think It is not explicitly mentioned in all datasheets. See page 224

 

 

[NiM]

Am I correct in understanding that I should set it to input mode and set VBDEN = 1?

[FBL]

Hi @NiM 

If your application is self powered, VBDEN is mandatory to enable vbus sensing.