SystemFrequency takes the right core clock frequency?

filippo2991 · ‎2010-04-27

Posted on April 27, 2010 at 15:22

Nickname12657_O · ‎2011-05-17

Posted on May 17, 2011 at 13:48

Hi,

You have just to update HSE_Value in your Toolchain preprocessor, by default it is defined in File \Libraries\CMSIS\Core\CM3\stm32f10x.h :

/**

* @brief In the following line adjust the value of External High Speed oscillator (HSE)

used in your application

Tip: To avoid modifying this file each time you need to use different HSE, you

can define the HSE value in your toolchain compiler preprocessor.

*/

#if !defined HSE_Value

#ifdef STM32F10X_CL

#define HSE_Value ((uint32_t)25000000) /*!< Value of the External oscillator in Hz */

#else

#define HSE_Value ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */

#endif /* STM32F10X_CL */

#endif /* HSE_Value */

SystemFrequency is computing the Frequency based on this ''Value''. Hope it helps you.

Cheers,

STOne-32.

filippo2991 · ‎2011-05-17

Posted on May 17, 2011 at 13:48

I'm using IAR, as far as I know I can add global defines as I would write

#define MYDEFINE

but not

#define MYDEFINE 0

Anyway, HSE_Value is se to the correct value (8M) but I get 72M as SystemFrequency. Am I running at that core frequency?

filippo2991 · ‎2011-05-17

Posted on May 17, 2011 at 13:48

probably I am missing something, but that HSE_Value is correctly set. If I printout its value it shows 8000000; that's the correct value for my HSE clock, yet the SystemFrequency shows 72000000 whether I am running at 36 or 8 MHz