【转】 STM32 入门教程 系统时钟 SysTick

void RCC_Configuration(void) 

{ 

    /* RCC system reset(for debug purpose) */ 

    RCC_DeInit(); 

    /* Enable HSE */ 

    RCC_HSEConfig(RCC_HSE_ON); 

    /* Wait till HSE is ready */ 

    HSEStartUpStatus = RCC_WaitForHSEStartUp(); 

    if(HSEStartUpStatus == SUCCESS) 

    { 

        /* HCLK = SYSCLK */ 

        RCC_HCLKConfig(RCC_SYSCLK_Div1); 

        /* PCLK2 = HCLK */ 

        RCC_PCLK2Config(RCC_HCLK_Div1); 

        /* PCLK1 = HCLK/2 */ 

        RCC_PCLK1Config(RCC_HCLK_Div2); 

        /* Flash 2 wait state */ 

        FLASH_SetLatency(FLASH_Latency_2); 

        /* Enable Prefetch Buffer */ 

        FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable); 

        /* PLLCLK = 8MHz * 9 = 72 MHz */ 

        RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9); 

        /* Enable PLL */ 

        RCC_PLLCmd(ENABLE); 

        /* Wait till PLL is ready */ 

        while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET) 

        { 

        } 

        /* Select PLL as system clock source */ 

        RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK); 

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

        while(RCC_GetSYSCLKSource() != 0x08) 

        { 

        } 

    } 

    /* Enable GPIOA and AFIO clocks */ 

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | 

                         RCC_APB2Periph_AFIO, ENABLE); 

}

void SysTick_Configuration(void) 

{ 

    /* Select AHB clock(HCLK) as SysTick clock source */ 

    SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK); 

    /* Set SysTick Priority to 3 */ 

    NVIC_SystemHandlerPriorityConfig(SystemHandler_SysTick, 3, 0); 

    /* SysTick interrupt each 1ms with HCLK equal to 72MHz */ 

    SysTick_SetReload(72000); 

    /* Enable the SysTick Interrupt */ 

    SysTick_ITConfig(ENABLE); 

}

volatile vu32 TimingDelay = 0; 

vu8 TestSig = 0;



void SysTickHandler(void) 

{ 

    TimingDelay--; 

    if(TimingDelay % 2) 

    { 

        TestSig = 1; 

    } 

    else 

    { 

        TestSig = 0; 

    } 

}

void Delay(u32 nTime) 

{ 

    /* Enable the SysTick Counter */ 

    SysTick_CounterCmd(SysTick_Counter_Enable); 

    TimingDelay = nTime; 

    while(TimingDelay != 0); 

    /* Disable the SysTick Counter */ 

    SysTick_CounterCmd(SysTick_Counter_Disable); 

    /* Clear the SysTick Counter */ 

    SysTick_CounterCmd(SysTick_Counter_Clear); 

}

    while(1) 

    {   

        GPIO_SetBits(GPIOA,GPIO_Pin_0); 

        Delay(100); 

        GPIO_ResetBits(GPIOA,GPIO_Pin_0); 

        Delay(100); 

        GPIO_SetBits(GPIOA,GPIO_Pin_1); 

        Delay(100); 

        GPIO_ResetBits(GPIOA,GPIO_Pin_1); 

        Delay(100); 

    }