STM32WLE5 + USART on LSE in STOP2 mode

MLe M.1 · ‎2026-05-26

Hello,

From STM32CubeMx we can see that USART1 can be drived from LSE. LSE is active in Stop mode2.

From datasheet, USART1 is off in stop mode 2.

Is it sure that USART1 can not work from Stop mode 2 with low datarate?

Best regards

Michel

Peter BENSCH · ‎2026-05-26

Correct, none of the USARTs can operate in STOP 2, as you can read in the datasheet, table 8. The LPUART was developed for this case, and it can operate in STOP 2.

Hope that answers your question?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Andrew Neil · ‎2026-05-26

@Peter BENSCH wrote:
The LPUART was developed for this cases

@MLe M.1 the clue is in the name, "LPUART" - the "LP" stands for Low Power

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

MLe M.1 · ‎2026-05-26

what is the maximum bps of LPUART1 using LSE?

MLe M.1 · ‎2026-05-26

I would like to have a 2nd LPUART .....

Andrew Neil · ‎2026-05-26

You can search here for STM32s with 2 or more LPUARTs:

https://www.st.com/content/st_com/en/stm32-mcu-developer-zone/mcu-portfolio.html

Looks like there are:

226 with 2 or 3
178 with exactly 2
48 with 3
none with >3

You could also ask SideKick - it tells me there's no WL with >1 LPUART:

How to use STM32 Sidekick

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.