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How do I switch PLLSource once it is running?

Question asked by David Harrison on Dec 7, 2016
Latest reply on Dec 10, 2016 by shingadaddy

Hi, I want to start off my STM32F745VET6 running on the PLL sourced from the 16MHZ HSI oscillator. I need to run some I2C code to initialize an external multi-output high accuracy clock generator chip where one of its outputs feeds a high accuracy 16MHz clock into the HSE input pin. I then want to switch over the PLL source from the HSI source to the HSE source. But I can't do that while the PLL is running so if I disable it first in order to switch the source and then re-enable it again, what happens to the system clock and the core while the PLL is disabled? Which clock runs the chip in the mean time?

 

BTW, I hate HAL to the death - it is pure bloatware - I am using my own bare metal code and don't use either HAL or STD_PERIPH.

 

Thanks.

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