Why the STM32WBA52CG SYSCLK must be 16MHz when the BLE was enabled

[Xiaojie]

HI，All

    I noticed that when we use BLE stack, we must set SYSCLK to 16MHz。When i set the SYSCLK upto 100MHz，the uart1 log will be garbled after call BleStack_Init which contained in st ble stack lib。I don't know if my discovery is correct。I don't understand why ST doesn't provide the source code for the Bluetooth protocol stack。

[STTwo-32]

Hello @Xiaojie 

For the UART problem, I think is related to the Baud rate or other UART configurations.

For the examples, You can take a look at the examples using NUCLEO-WBA55CG.

And you can adapt them to the STM32WBA52CG.

Best Regards.

STTwo-32

[Xiaojie]

Hi, 

   Thank you for your replay.

    I open a ble_beacon project in STM32Cube_FW_WBA_V1.2.0 which adapted for NUCLEO-WBA55CG。

   The default SYSCLK and HCLK1 is 16MHz， when i changed the System Clock Mux to PLLCLK,  Then SYSCLK is up to 64MHz，the STM32CubeMX noticed me that the System Clock must be <= 16MHz。

  Why the STM32CubeMX noticed this error？

Thanks

[STTwo-32 · Accepted solution]

Hell again @Xiaojie 

The maximum SYSCLK is 100MHz for voltage scaling range 1 and 16Mhz for voltage scaling range 2:

So, to be able to have a SYSCLK up to 100MHz, you need to change the voltage scaling range from 2 to 1:

Best Regards.

STTwo-32

[Xiaojie]

Thank you very much！！

[Xiaojie]

HI，

   I notify that the ble stack will modify the RCC configuration。You can see my another issue:

https://community.st.com/t5/stm32-mcus-wireless/ble-stack-modify-the-rcc-configuration/td-p/667539

So if we choose SYSCLK or PCLK2 as usart clock and init the usart befor calling BleStack_Init, the frequency of usart clock will change after calling BleStack_Init. Then the usart will be garbled.

Thanks