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Rita
Visitor II
December 16, 2025
Solved

STM32L051: select LSE as LPUART clock source for wakeup from stop mode?

  • December 16, 2025
  • 2 replies
  • 505 views
Can STM32L051 set LSE be LPUART clock source to wake up the MCU? If yes, how to configure.
Best answer by Gyessine

Hello @Rita 
Based on your product Datasheet, yes, a 32.768 kHz clock (LSE) is needed to allow LPUART communication up to 9600baud. Therefore, even in Stop mode, the LPUART can wait for an incoming frame while having an extremely low energy consumption. 
except if you have the STM32L051K6, it does not support LPUART

Gyessine_0-1766049438748.png

to configure it, just enable your LSE in your RCC configuration

Gyessine_1-1766049894534.png

enable your LPUART

Gyessine_2-1766049928739.png

and select LSE as input for LPUART in clock configuration

Gyessine_3-1766049981767.png

this article maybe helpful for you also
Hope that answered your question, if yes please mark it as solution to close this thread
Gyessine

 



2 replies

KnarfB
Super User
December 16, 2025
GyessineBest answer
Technical Moderator
December 18, 2025

Hello @Rita 
Based on your product Datasheet, yes, a 32.768 kHz clock (LSE) is needed to allow LPUART communication up to 9600baud. Therefore, even in Stop mode, the LPUART can wait for an incoming frame while having an extremely low energy consumption. 
except if you have the STM32L051K6, it does not support LPUART

Gyessine_0-1766049438748.png

to configure it, just enable your LSE in your RCC configuration

Gyessine_1-1766049894534.png

enable your LPUART

Gyessine_2-1766049928739.png

and select LSE as input for LPUART in clock configuration

Gyessine_3-1766049981767.png

this article maybe helpful for you also
Hope that answered your question, if yes please mark it as solution to close this thread
Gyessine

 



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