STM32H573V UCPD CC2 and PC9 interference

[DirkH]

HI,

I am working on a board using STM32H573V and have a working solution with UCPD detecting an inserted memory stick and running the MSC class. In an other part of the software I am using PC9 as an GPIO push-pull, low speed output and as soon as I set it to high, the voltage at PB14 (UCPD CC2) drops from 3.3V to 1.5V and my UCPD handler signals a device attached and turns VBUS on even though nothing is attached. There is no other electrical connection between PC9 and PB14 on the board. I am using a TCPP03-M20 for VBUS switching. The board is acting as VBUS source.

[waclawek.jan · Accepted solution]

PC9 is UCPD1_DB2 i.e. part of the dead-battery mechanism ; and as such, gates the pull-down at PB14=UCPD1_CC2.

Set PWR_UCPDR.UCPD_DBDIS bit to disable this behaviour.

JW

[DirkH]

Thank you for the swift reply, Jan ! Problem solved :))