2025-07-11 12:11 PM
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 ?
2025-07-11 12:33 PM
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
2025-07-11 1:32 PM
Thank you, so I can flash and debug without the STLINK_RX / STLINK_TX then?
2025-07-11 1:51 PM
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.