STM32WBA family use of stack BLE without LSE (with LSI2)

[Wladimiro_Gaiotti]

Hi to all!

We are developing a low-cost application, with in mind STM32WBA52KE, which use a 32 pin package.

Due to short number of pin, we would use pin 12 and 13 as GPIO, so we should not use the LSE.

Is it possible to manage the BLE stack without LSE, using LSI2? If yes, which kind of limitation we will have?

I can't find the right answer on documentation, can you help me?

Thank you very much in advance.

[STTwo-32]

Hello @Wladimiro_Gaiotti and welcome to the ST Community.

Yes, you can implement a BLE application using the STM32WBA52 without LSE. In this case, you will have to use HSE/1000 as clock source for the radio sleep timer clock. As mentioned on the release note of STM32CubeWBA package v1.4.1, LSI2 is not supported as clock source for the radio sleep timer clock.  Using HSE also will limit you on Low power modes to sleep mode. 

Best Regards.

STTwo-32

 

[rajdeep_01]

Hi @STTwo-32,

- Implemented near similar case, that not used LSE, results issue in BLE connection.
- As BLE requires Radio Sleep Timer Clock, for which two options available:
Option-1. HSE/1000: Implemented, tested and found that BLE advertisement works but connection not works.
Option-2. LSE: Implemented, tested and found that BLE advertisement and connection works perfectly.
Seems, LSE is mandatory for BLE operations.

- Further, in reference manual mentioned that LSI2 is available for STM32WBA54/55xx devices,
Means, not available for STM32WBA52xx devices:

- Can you please provide guidance, related to which source require for Radio-Sleep-Timer-Clock,
And how to make BLE working properly, is that further configuration requires?

Thanks

[STTwo-32]

Hello @rajdeep_01 

Maybe my first answer was not clear. I've updated my answer with more details that you may check.

Best Regards.

STTwo-32

[Sebastien DENOUAL]

Hi @rajdeep_01 , Hi @Wladimiro_Gaiotti ,

Let me update this old topic with some news :

I confirm there is two valid options to run BLE over STM32WBA52 without LSE.  Both solutions are validated for BLE.

1. Option #1 : Running using HSE_DIV100

   I do confirm that it is possible to use HSE_DIV1000 for BLE.

PeriphClkInit.RadioSlpTimClockSelection = RCC_RADIOSTCLKSOURCE_HSE_DIV1000;

Of course, using HSE_DIV1000, it is no more possible to mange low_power_mode as HSE must remains always active. 

Low power mode must so  be disabled : 

#define CFG_LPM_LEVEL (0)

To ease testing of HSE_DIV1000 over CubeFW code example, you may use attached .pdf doc - I tested it on STM32CubeFW code example running over Nucleo-WBA55 board  (tested using BLE_P2P_Server and BLE_HeartRate) code examples. 

• Option #2 :Running using LSI2

Since last CubeFW delivery v1.6, LSI2 usage is now possible. 

More details here : https://wiki.st.com/stm32mcu/wiki/Connectivity:STM32WBA_without_LSE_crystal

 

Regards,
Sebastien.