How to use LSI instead of LSE with STM32WBA55

[ledi001]

Hi,

I use the example “BLE_p2pServer_ota” with NUCLEO-WBA55 as a template for a project.
For space reasons and to save costs, I would like to use the internal oscillator LSI1 (32,000kHz) instead of the external 32,768 chrystal LSE. After switching to LSI1 with CubeMX, the advertising works, but a connection can no longer be established. Which workaround is required to use the LSI?

[STTwo-32 · Accepted solution]

Hello @ledi001 

Do you mean you have replaced LSE with LSI1 in all peripherals that uses LSE. If so, The LSI1 must not be used for the 2.4 GHz RADIO sleep timer.

Best Regards.

STTwo-32

[ledi001]

Hello @STTwo-32 

Thank you for your reply. Does this mean that there is no other option than to use the LSE in this case?

[Tesla DeLorean]

Only the LSE lives in the Backup Domain wrt to power, on the STM32WB55 and frankly most of the STM32 families

[STTwo-32]

You have also the option of LSI1 and HSE but the LPM Will not be available.

Best Regards.

STTwo-32

[ledi001]

Thanks for your help!
The energy-saving modes (LPM) with BLE are an essential part of my application. I will therefore discard the idea of using the LSI and use the LSE.