clock problem

[614678489]

Posted on August 12, 2012 at 15:25

I want to use the HSI, and the code is like the following:

void RCC_Configuration(void) {  RCC_DeInit();  RCC_HSICmd(ENABLE);  RCC_AdjustHSICalibrationValue(0);  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_AFIO|RCC_APB2Periph_USART1,ENABLE); } There is no error during the compilation, but the hardware debug is kind of strange, as shown in the attached. CFGR=0 means that MCO=0, which then indicates that there is no clock at all.... What's wrong ?

[Tesla DeLorean]

Posted on August 12, 2012 at 20:30

For your unspecified STM32Fxxx part you might need to consider enabling the PWR/BKP clock, and unlocking the BKP domain.

[614678489]

Posted on August 13, 2012 at 02:43

Thanks, my part is STM32F107

[jmelchior9]

Posted on August 13, 2012 at 15:23

check if the RCC_CR register value is : 0x0000 XX83 where X is undefined.

In default mode, the HSI clock is enabled.

[Tesla DeLorean]

Posted on August 13, 2012 at 16:38

Sorry, had read LSI/LSE there.

With the HSE/HSI/PLL one has to make sure not to remove the clock from the CPU, and to bring up, and wait for each to be ready before switching over.