STM32F103系统时钟配置

STM32F103系统时钟完美配置

时钟树的理解确定分频倍频之后再做

• STM32F103时钟树

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-KXW3Vwk8-1591952361435)(https://cloud.githubusercontent.com/assets/13186592/21471246/f70cdcae-cae5-11e6-982f-d94bc187c670.jpg)]

• 假设外接晶振8MHz，现在需要配置出系统72MHz时，需要

配置代码(外部晶振8MHz配置系统时钟为72MHz)

/*RCC config*/
void RCC_Configuration(void)
{
    RCC_DeInit();  
    RCC_HSEConfig(RCC_HSE_ON);
    while(SUCCESS != RCC_WaitForHSEStartUp()){}	
    /*设置FLASH存储器延时时钟周期数*/
    FLASH_SetLatency(FLASH_Latency_2);    //FLASH_Latency_2  2延时周期 
    /*选择FLASH预取指缓存的模式*/ 
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);     // 预取指缓存使能
    /*设置PLL时钟源及倍频系数*/  
    /* Fcpu = (PLL_src * PLL_MUL) = (8 Mhz / 1) * (9) = 72Mhz   */ 
    RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);  			
    /* Enable PLL */
    RCC_PLLCmd(ENABLE);	
     /*检查指定的RCC标志位(PLL准备好标志)设置与否*/    
    while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET) {}
    /* Set system clock dividers */
    RCC_HCLKConfig(RCC_SYSCLK_Div1);
    RCC_PCLK2Config(RCC_HCLK_Div1);
    RCC_PCLK1Config(RCC_HCLK_Div2);
    RCC_ADCCLKConfig(RCC_PCLK2_Div6);	
    /* Embedded Flash Configuration */
    FLASH_SetLatency(FLASH_Latency_2);                           
    FLASH_HalfCycleAccessCmd(FLASH_HalfCycleAccess_Disable);
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
    /*SYSCLK configuration*/
    RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
}

/*NVIC config*/
void NVIC_Configuration(void)
{
    /* Configure and enable ADC interrupt */
    NVIC_SetVectorTable(NVIC_VectTab_FLASH,0);
    /* Configure the NVIC Preemption Priority Bits */
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
}

void bsp_init(void){
    RCC_Configuration();
    NVIC_Configuration();
    SysTick_Config(72000);   //1ms  
}