Nucleo-L433RC-P: How to access STLINK_RX pin

[freeflyer]

I am using the Nucleo-L433RC-P board and want to use LPUART RX on pin PA3.

But the schematic shows that pin PA3 is used for STLINK_RX.  What is STLINK_RX / STLINK_TX used for ?

Can I remove SB75 to access the pin or would this stop STLINK from working ?

[KnarfB · Accepted solution]

STLINK_RX / STLINK_TX are used for serial communication with a host via the ST-LINK USB connection (virtual COM port). If you don't need that, you are free to use these pins for other purposes.

>  would this stop STLINK from working

not the debug function, only the serial comm.

hth

KnarfB

[freeflyer]

Thank you, so I can flash and debug without the STLINK_RX / STLINK_TX then?

[Tesla DeLorean]

Yes, it's just a comms link for debugging via the VCP, connecting to an STM32L433 UART. On the NUCLEO-64 designs this often conflicts/shares with the Arduino D0/D1 shield connection.

One could use the PB3/SWO for Serial Wire Viewer (SWV)

The programming via JTAG/SWD is via the SWDIO/SWCLK connection.

[Andrew Neil]

Indeed, as @Tesla DeLorean said, the VCP (UART) and SWD (Debug/Programming) connections are separate - you can use either one without the other.

See the User Manual:

https://www.st.com/resource/en/user_manual/um2206-stm32-nucleo64p-boards-mb1319-stmicroelectronics.pdf#page=12

via: https://www.st.com/en/evaluation-tools/nucleo-l433rc-p.html#documentation