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mahmoud boroumand
mahmoud boroumand
Associate III
August 17, 2017
Solved

bypass config with STDPERIPH_DRIVER

  • August 17, 2017
  • 4 replies
  • 976 views
Posted on August 17, 2017 at 13:05

hello 

i use stm32f030f4 and use 10MHz oscillator (BYPASS) and i want achieve to 48mhz in mcu.

and i use STDPERIPH_DRIVER and keil v5.what configuration i have to do ?what code i have to add to my project?

    This topic has been closed for replies.
    Best answer by Tesla DeLorean
    Posted on August 17, 2017 at 19:00

    RCC_HSEConfig(RCC_HSE_ON); becomes RCC_HSEConfig(RCC_HSE_Bypass); and you don't need to wait for it to start

    or something along these lines in system_stm32f0xx.c, called via SystemInit()

    static void SetSysClock(void)

    {

    /******************************************************************************/

    /*            HSE BYPASS used as System clock source                          */

    /******************************************************************************/

      /* SYSCLK, HCLK, PCLK configuration ----------------------------------------*/

      /* Enable HSE BYPASS */

      RCC->CR |= ((uint32_t)RCC_CR_HSEBYP);

      /* Enable Prefetch Buffer and set Flash Latency */

      FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY;

      /* HCLK = SYSCLK */

      RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;

      /* PCLK = HCLK */

      RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE_DIV1;

      /* Select HSE as system clock source */

      RCC->CFGR = (RCC->CFGR | (uint32_t)((uint32_t)~(RCC_CFGR_SW))) | (uint32_t)RCC_CFGR_SW_HSE;

      /* Wait till PLL is used as system clock source */

      while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_HSE);

    }

    4 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 17, 2017
    Posted on August 17, 2017 at 13:38

    You'd need to modify the clock/pll setting code in system_stm32f0xx.c

    Not sure the available multiplier and divider settings will get you from 10 MHz to 48 MHz, review the setting options in the reference manual.

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    mahmoud boroumand
    mahmoud boroumandAuthor
    Associate III
    August 17, 2017
    Posted on August 17, 2017 at 13:52

    If i want get 10MHz to 10 mhz what code i have to add?

    i dont know how enable bypass.

    RomainR.
    RomainR.
    ST Employee
    August 17, 2017
    Posted on August 17, 2017 at 17:49

    Hi,

    HSE 10MHz input frequency does not allow you to get the 48MHz SYSCLK with PLL.

    HSE PREDIV is between 1 and 16

    PLLMul is between 2 and 16

    But you can with a HSE frequncy of 8MHz or 12MHz

    For 8Mhz PLL Input:

    HSE_PREDIV = 1

    PLL_MUL = 6

    For 12Mhz PLL Input:

    HSE_PREDIV = 1

    PLL_MUL = 4

    BR

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