About the LSE Crystall to the STM32WB55

[AMova.2]

In STM32WB55 the LSF must be 32KHz or it can be others like 42KHz etc. as well?

Thanks.

[Foued_KH]

Hello @Community member​ ,

The typical LSE frequency is 32KHz (from STM32WB55 DS)

Foued

[AMova.2]

Dear Khalsi,

Thank you for your reply. Yes, I agree that the typical value for the LSE crystal is 32KHz. So, according to the table shown above we can select up to maximum 44.4 KHz for the LSE crystal. If we select 42 KHz for the LSE this would not violet the BLE portion of the STM32WB55RG please?

Thanks,

ALi.

[AMova.2]

Dear Khalsi,

I did search in the community, and I found a similar type of question,

STM32WB55 custom board and 32Khz crystal

Imen refers to the AN5042 "Application note Precise HSE frequency and startup time tuning for STM32 wireless MCUs". I did check this App and I did not see any information regarding the 32KHz LSE. I am assuming that LSE has no role in the functionality of the BLE portion of the STM32WB55 please. According to your table I can select different frequencies beside 32 KHz as long as I follow the limit.

Please comment.

Thanks for your help.

[Remy ISSALYS · Accepted solution]

Hello,

It is highly recommended to use an LSE crystal at 32 kHz for BLE application.

Best Regards