Taken from the datasheet Pg. 186 "When VBUS sensing feature is enabled, PA9 and PB13 should be left at their default state (floating input), not as alternate function. A typical 200 μA current consumption of the sensing block (current to voltage conversion to determine the different sessions) can be observed on PA9 and PB13 when the feature is enabled"

I'm not too sure what this means - will it draw 200 uA from PA9 and PB13 when the USB is plugged in ? Right now I have PA9 connected to VUSB, but PB13 connected to an ethernet TXD signal (Unforunately I don't think I'll be able to move the signal to the other place where it's offered - PG14.

I've made my design in STM32CubeMX and it seems perfectly fine (all greens).

Will it be ok to leave PB13 connected to the ethernet signal ?

Thanks in advance!

  • \$\begingroup\$ The page you are quoting is 186 instead of 190. \$\endgroup\$
    – user162889
    Sep 21, 2017 at 22:55

1 Answer 1


The note in the datasheet should concern you if you have VBUS detection enabled. PA9 and PB13 are used for that and thus they can't be connected to other peripherals in such case.

If you don't need to sense USB VBUS, just disable that feature. It can be done by clearing the appropriate bit in the OTG_GCCFG register (check the Reference Manual page 1587), although possibly they may are easier higher level ways if you are using standard or HAL libraries. If you say Cube MX didn't complain, probably it didn't enable it as it's disabled by default, but you can't never know with Cube MX, better check.

In short, make sure that VBUS sensing is disabled and you're good.

  • \$\begingroup\$ Ah I see. I wanted to use VBUS sensing :( \$\endgroup\$
    – VanGo
    Sep 22, 2017 at 6:17

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