GPIO is disturbed by the alternate function

zli.2 · ‎2022-10-20

hello everyone,

i work on stm32g071 to build a application , but i configure the PA9 for uart TX and the PA8 for the normal input that pull up by 3.3v. When start send data by the PA9 , PA8 is disturbed。But PA9 is not configured, the PA8 level is normal

gbm · ‎2022-10-20

Shorts on the board? Too high current drawn from PA9?

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice

zli.2 · ‎2022-10-20

No short,but i don`t test the cuurent on the PA9. So , if the current too high ,What should i do?

ONadr.1 · ‎2022-10-21

You can use tranzistor, or some digital buffer. It depends on current, frequency, cost etc....

waclawek.jan · ‎2022-10-21

This is the USBC-PD dead-battery gotcha. Have a look at SYSCFG1_CFGR1.UCPDx_STROBE.

JW