Connecting external device to B-WL5M-SUBG1 via UART

[1ntelligentmoron]

Hi all,

I am new to development with STM32, and I want to connect an external RFID card reader to my STM32WL5MOC, which is on the B-WL5M-SUBG1 board. I tried looking for tutorials on how to do this but nothing useful came up.

The user manual (UM3127, https://www.st.com/resource/en/user_manual/um3127-stm32wl5moc-connectivity-expansion-board-stmicroelectronics.pdf), in Section 7.6, outlines which solder bridges should be ON/OFF to configure the board between SPI and UART. Upon inspecting the solder bridges on my board (default configuration), I noticed that it is configured for SPI.

My understanding is that even if I connect my RFID card reader to the correct pins of the board, I still will not be able to establish a UART connection because there is physically not an electrical connection. Is this correct?

Should I un-solder the solder bridges that are configured for SPI and solder them in the right place for UART? Is there any other way to do it without altering the electrical connection of the board?

[Andrew Neil]

Welcome to the forum - do you have experience with any other microcontroller(s) ?

I would check the schematics, to be sure

It is standard ST practice that schematics are on the 'CAD Resources' tab of the board's Product Page:

https://www.st.com/en/evaluation-tools/b-wl5m-subg1.html#cad-resources

Some STM32 "getting started" resources:

https://community.st.com/t5/stm32-mcus-products/for-better-learning-stm32-programming-and-debugging/m-p/719468/highlight/true#M260690

[STTwo-32 · Accepted solution]

Hello @1ntelligentmoron 

ta be able to use the UART1 of the B-WL5M-SUBG1 board, you have to solder the SB1, SB4, SB16 and SB19 and unsolder the SB3, SB6, SB18 and SB22 an as you can see on the table 13 of the UM3127-Rev3.

Best Regards.

STTwo-32