STM32U5A Wake-UP from stop mode 3

[bjackson96]

Hello all,

I am using the STM32U5A5QJ in a project and I had a question about some of the wake-up modes. I would like the microcontroller to be in stop mode 3 most of the time until it receives an interrupt from a sensor to return to normal mode. The data sheet seems to specify two ways of doing this and I’m wondering which is correct or if both can be used.

1. In Table 9. STM32U5Axxx modes overview it says the wake-up source for stop mode 3 is one of the 24 WKUPx I/O’s.
2. There is also a section under Extended interrupt/event controller (EXTI) where it says “The EXTI wake-up requests allow the system to be woken up from Stop modes.”

They both seem to say that they can be used to wake-up from stop mode, is this correct or should one be used over the other?

Thanks for your help,

[STTwo-32 · Accepted solution]

Helll @bjackson96 and welcome to the ST COMMUNITY :smiling_face_with_smiling_eyes:.

According to the RM0456, you can exit the STOP 3 mode using WKUPx pin edge, RTC/TAMP event/interrupt, NRST pin external reset, IWDG reset, BOR reset. 

Best Regards.

STTwo-32 

[bjackson96]

Thank you so much for getting back to me so quickly! 

Thanks for the clarification.