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Senior II
July 11, 2025
Solved

Nucleo-L433RC-P: How to access STLINK_RX pin

  • July 11, 2025
  • 1 reply
  • 397 views

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 ?

 

freeflyer_0-1752260333226.png

 

Best answer by KnarfB

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

1 reply

KnarfB
KnarfBBest answer
Super User
July 11, 2025

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

freeflyerAuthor
Senior II
July 11, 2025

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

Tesla DeLorean
Guru
July 11, 2025

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.

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