stm32F407（CORTEX-M4）之RCC配置与TIM2的PWM

（我的外部时钟为25MHz）

#include

static __IO uint32_t TimingDelay;    //__IO为volatile的宏定义
int8_t LED_Flag = 1;       //LED灯翻转标志位

void RCC_Config(void);
void GPIO_Config(void);
void TIM_Config(void);
void NVIC_Config(void);
void Delay(__IO uint32_t nTime);

main ()
{
RCC_Config();
GPIO_Config();
TIM_Config();
NVIC_Config();

RCC_MCO1Config(RCC_MCO1Source_PLLCLK, RCC_MCO1Div_1);

if (SysTick_Config(SystemCoreClock / 1000))
 { 
  
 while (1);
 }
while (1)
    {
  
  if (LED_Flag != 1)
  {
    GPIO_SetBits(GPIOG, GPIO_Pin_6);      //setbits使能IO，当前下指输出（此时为灭）
  }       
  else
  {
    GPIO_ResetBits(GPIOG, GPIO_Pin_6);     //Resetbits屏蔽IO，当前下指不输出（此时为亮）
  }
    }
}

void RCC_Config(void)
{
RCC_DeInit();              //RCC寄存器初始化
RCC_HSEConfig(RCC_HSE_ON);  //使用外部时钟
if (RCC_WaitForHSEStartUp() == SUCCESS) //等待外部时钟启动
  {
   RCC_PLLCmd(DISABLE);                    //配置PLL前应先关闭主PLL
   RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK); //选择PLL时钟为系统时钟
   RCC_HCLKConfig(RCC_SYSCLK_Div1);     //HCLK(AHB)时钟为系统时钟1分频
   RCC_PCLK1Config(RCC_HCLK_Div4);     //PCLK1(APB1)时钟为HCLK时钟8分频，则TIM2时钟为HCLK时钟4分频
   RCC_PCLK2Config(RCC_HCLK_Div2);     //PCLK2(APB2)时钟为HCLK时钟2分频
   RCC_PLLConfig(RCC_PLLSource_HSE, 25, 336, 2, 7); //PLL时钟配置，公式详见‘system_stm43f4xx.c’ Line149
   RCC_PLLCmd(ENABLE);        //PLL时钟开启
   while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET) { } //等待PLL时钟准备好
  }
}

 
void GPIO_Config(void)
{

GPIO_InitTypeDef GPIO_InitStructure;

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG | RCC_AHB1Periph_GPIOA, ENABLE);

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;     //指定第六引脚
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;    //模式为输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   //频率为快速
GPIO_Init(GPIOG, &GPIO_InitStructure);      //调用IO初始化函数

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;     //指定第一引脚
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;    //模式必须为复用！
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   //频率为快速
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;        //上拉与否对PWM产生无影响
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_TIM2);//复用ＧＰＩＯＡ＿Ｐｉｎ１为ＴＩＭ２＿Ｃｈ２

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;  
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_MCO);
}

void TIM_Config(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
TIM_DeInit(TIM2);//初始化TIM2寄存器

TIM_TimeBaseStructure.TIM_Period = 10000-1; //查数据手册可知，TIM2与TIM5为32位自动装载

TIM_TimeBaseStructure.TIM_Prescaler = 8400-1;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//向上计数
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

TIM_OCStructInit(&TIM_OCInitStructure);  //填入缺省值，其中后几项只对TIM1和TIM8有效
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //PWM1为正常占空比模式，PWM2为反极性模式
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 2000; //输入CCR（占空比数值）
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //High为占空比高极性，此时占空比为20%；Low则为反极性，占空比为80%
TIM_OC2Init(TIM2, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable);//CCR自动装载默认也是打开的
TIM_ARRPreloadConfig(TIM2, ENABLE); //ARR自动装载默认是打开的，可以不设置

TIM_ClearFlag(TIM2, TIM_FLAG_Update);
TIM_ITConfig(TIM2, TIM_IT_Update,ENABLE);
TIM_Cmd(TIM2, ENABLE); //使能TIM2定时器
}

void NVIC_Config(void)
{

NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); //中断优先级分组为1
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn; //嵌套中断通道为TIM2
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; //抢占优先级为1
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;    //响应优先级为0
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;     //使能中断
NVIC_Init(&NVIC_InitStructure);
}

void Delay(__IO uint32_t nTime)
{ 
  TimingDelay = nTime;
  while (TimingDelay != 0);
}

void TimingDelay_Decrement(void)
{
  if (TimingDelay != 0x00)
  { 
    TimingDelay--;
  }
}

中断服务函数：

void TIM2_IRQHandler(void)
{
  if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
  {
    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
 LED_Flag= ~LED_Flag;

 
  }   
}