STM32H573 PB14

[gaso111]

In our project I use STM32H573VIT6 LDO uC.

We have a problem with the PB14 pin. We use 3 pins for LED control (PB10, PB13 and PB14, see photo). The problem with the PB14 is that the LED lights up dimly without code initialization.

If PB14 is initialized as Output, Open Drain, No Pullup-Pulldown, it lights up dimly in the OFF state and normally in the ON state.

With Output Push-Pull initialization it works normally, i.e. in the OFF state the LED does not light up and in the ON state it lights up normally.

1. What could be the problem?

2. Should I use PB14 at all and is there a potential risk of later problems?

[gaso111]

Thank you @Tesla DeLorean 

And what configuration do the GPIOs have then?

[STOne-32]

Dear @gaso111  @AScha.3 

Is that possible to not leave PC9 GPIO floating and try to connect it to Ground or VDD, just for testing purposes to see if the PB14 behavior still the same ?   The hypothesis may be the USB-PD Battery dead function is taking the control by default.   Let us know.

STOne-32.

[Tesla DeLorean]

>>And what configuration do the GPIOs have then?

I don't know, these aren't MY monkeys..

If they were I'd probably disassemble the ROM and make some educated guess, or physically establish it.

[AScha.3]

Dear @STOne-32  ,

i tried PC9 -> GND : LED dark, also on hard reset . 

And in my program i use SDMMC , PC9 here with pullup (and sd-card D1 ), PC9 at 3.3V : LED lights up dimly .

So there is an undocumented hardware, independent from cpu (run, reset ), that switches a 12Kohm pulldown on PB14 , if PC9 is not at GND .

Is this then an addition to the errata or for the datasheet ? Now its not documented , afaik.

[AScha.3]

> And what configuration do the GPIOs have then?

see rm:  (What they should do...except our story about PB14...so far... )

So (most) pins are at analog mode.

[STOne-32]

Dear @AScha.3 ,

More information are here Introduction to USB Type-C® Power Delivery for STM32 MCUs and MPUs - Application note on Battery dead function when the MCU is not powered with CC1/CC2 and DBCC1/DBCC2 pins ( additional functions) that present that Rd value of 5.1Kohm.  We will be back to you with more details to clarify the I/Os states after reset for these particular ones.

Cheers,

STOne-32.