How to find value of APB1 Clock in STM32F429

clock stm32 stm32f4discovery
user2870154 picture user2870154 · Nov 27, 2014 · Viewed 11.8k times · Source

Can anyone tell me how to find the APB1 clock frequency of STM32F429? And how to calculate the Baud Rate of STM32F429.

P.S...Please dont tell to refer Reference Manual,as those works are already done and I would like to tell me the exact value of APB1 Clock frequency

Thankyou

Answer

Andy Brown picture Andy Brown · Nov 28, 2014

Using the standard peripheral library, include stm32f4xx_rcc.h then call void RCC_GetClocksFreq(RCC_ClocksTypeDef* RCC_Clocks) and it will fill in the structure that you pass with the values of all the bus clocks.

The correctness of the answer depends on the value you set for HSI_VALUE or HSE_VALUE (a global uint32_t set to the value in Hz of your system's oscillator). You can find it in your application's startup C file.

You should review the values in the startup file to ensure that the core clock is generated from the source that you expect it to be (usually the PLL via the internal (HSI) or external (HSE) crystal). If they are correct and match the aforementioned global constant then the answers given by RCC_GetClocksFreq will be correct.

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