STM32WB clock understanding

[HardWins]

Hello everyone,

New to the world of STM32 and moving from Arduino programming to more in-deep STM32 one, I faced an issue that I solved in a way I can't understand.

I started working on a basic Blink program using STM32WB5MM-DK and the in-board RGB PWM led. I understood a little bit late that i had to configure the interrupts and clocks but well, that's how we learn.

But I still don't understand - at least - one thing. In the Clock Configuration (.ioc file) I can't get a working program if the system clock is set less to 48MHz and after some iterations, I discovered that it was in fact the APB2 timer clock that had to be at least 48MHz. In the datasheet(s) I can't find any indication on this critical value.

Is there any logic behind this value ? Or is it a side effect of something that I have not already understood ?

 

 

My program is pretty similar to the led.c code in BSP example

 

Thanks !

[STTwo-32]

Hello @HardWins and welcome to the ST Community :smiling_face_with_smiling_eyes:.

According to the Table 24 of the DS11929, the internal APB2 clock frequency can take any value between 0 and 64MHz:

PS: you can take a look at the clock configuration of the examples that are using the same board. you will find that the APB2 can take different values (not more than 48Mhz).

Best Regards.

STTwo-32