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STM32F407 Ext Crystal

Question asked by White.John on Aug 29, 2014
Latest reply on Aug 29, 2014 by White.John
Dear Community,

I am using the STM32F407 for the first time and require to set up CAN into a Peak CAN Tx/Rx Module.
I have an external crystal of 8 MHz, the file <stm32f4xx.h> appears not to set the HSE_VALUE to 8000000.

#if !defined  (HSE_VALUE)
#define HSE_VALUE    ((uint32_t)25000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */


I have set #define HSE_VALUE ((unit32_t) 8000000) but this appears to be reset back to 25000000.

With the 8 MHz crystal CAN error occur, fitting a 25 MHz crystal all is OK, but need to understand why this error occurs, as I may need to change crystal frquencies.

Any help would be appreciated.

Regards .... John W





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