论坛 › 问答 › STM32F030F4P6系统时钟必须和AHB时钟一致吗

yanggong 发表于 2015-11-21 15:59:50

STM32F030F4P6系统时钟必须和AHB时钟一致吗

STM32F030F4P6 外部晶振8M设置AHB为系统时钟的2-512分频，程序在执行完初始化后就不在执行了，这是为什么 ？   不分频就可以执行

安 发表于 2015-11-21 16:11:43

时钟配置错误。

yanggong 发表于 2015-11-21 16:15:05

if (HSEStatus == (uint32_t)0x01)
{
    /* Enable Prefetch Buffer and set Flash Latency */
    FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY;

    /* HCLK = SYSCLK */
    RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV2;//这里改成2分频就不行了
   
    /* PCLK = HCLK */
    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE_DIV1;

chifen 发表于 2015-11-21 16:31:32

不能只看这里一点，要看你的 是不是启用了外部时钟，你倍频是多少，才能知道下面的分频

yanggong 发表于 2015-11-21 16:33:44

static void SetSysClock(void)
{
__IO uint32_t StartUpCounter = 0, HSEStatus = 0;

/******************************************************************************/
/*            PLL (clocked by HSE) used as System clock source                */
/******************************************************************************/

/* SYSCLK, HCLK, PCLK configuration ----------------------------------------*/
/* Enable HSE */   
RCC->CR |= ((uint32_t)RCC_CR_HSEON);

/* Wait till HSE is ready and if Time out is reached exit */
do
{
    HSEStatus = RCC->CR & RCC_CR_HSERDY;
    StartUpCounter++;
} while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

if ((RCC->CR & RCC_CR_HSERDY) != RESET)
{
    HSEStatus = (uint32_t)0x01;
}
else
{
    HSEStatus = (uint32_t)0x00;
}

if (HSEStatus == (uint32_t)0x01)
{
    /* Enable Prefetch Buffer and set Flash Latency */
    FLASH->ACR = FLASH_ACR_PRFTBE | FLASH_ACR_LATENCY;

    /* HCLK = SYSCLK */
    RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV2;
   
    /* PCLK = HCLK */
    RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE_DIV1;

    /* PLL configuration */
    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL));
    RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_PREDIV1 | RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLMULL2);
    RCC_PREDIV1Config( RCC_PREDIV1_Div2);        
    /* Enable PLL */
    RCC->CR |= RCC_CR_PLLON;

    /* Wait till PLL is ready */
    while((RCC->CR & RCC_CR_PLLRDY) == 0)
    {
    }

    /* Select PLL as system clock source */
    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
    RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;   

    /* Wait till PLL is used as system clock source */
    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_PLL)
    {
    }
}
else
{ /* If HSE fails to start-up, the application will have wrong clock
         configuration. User can add here some code to deal with this error */
}
}

chifen 发表于 2015-11-21 16:50:29

system_stm32f0xx.c 里看一下
#define PLL_SOURCE_HSI      // HSI (~8MHz) used to clock the PLL, and the PLL is used as system clock source
//#define PLL_SOURCE_HSE      // HSE (8MHz) used to clock the PLL, and the PLL is used as system clock source
//#define PLL_SOURCE_HSE_BYPASS // HSE bypassed with an external clock (8MHz, coming from ST-Link) used to clock
   你启用的是哪个

yanggong 发表于 2015-11-21 19:29:00

外部8M ，第二个

chifen 发表于 2015-11-21 19:44:50

调试了你的代码，如果是第二个 可以正常运行的

yanggong 发表于 2015-11-21 22:32:47

麻烦您帮我看下这个代码，程序执行完初始化 while（1）就不执行了，AD采样也不执行了

查看完整版本: STM32F030F4P6系统时钟必须和AHB时钟一致吗