TIM2+DMA配置

void TIM2_Cap_Init(u16 arr,u16 psc)
{     
    GPIO_InitTypeDef GPIO_InitStructure;//初始化GPIO结构体
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;//初始化计时器结构体
     NVIC_InitTypeDef NVIC_InitStructure;//中断配置结构体

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);    //TIM2时钟使能
     RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);  //GPIOA时钟使能
    
    GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_0;  
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PA0输入
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    GPIO_ResetBits(GPIOA,GPIO_Pin_0);            //PA0清除之前配置             
    

    TIM_TimeBaseStructure.TIM_Period = arr;     //预分频(时钟分频) 比如：72M/(arr+1)=24M
    TIM_TimeBaseStructure.TIM_Prescaler =psc;   //计数值TIMx->CNT达到psc后会触发中断
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //时钟不分频
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数
    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;//是重复计数，就是重复溢出多少次才给你来一个溢出中断,
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); 
  
    
        TIM2_ICInitStructure.TIM_Channel = TIM_Channel_1; //选择通道1
        TIM2_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;    //上升沿触发
        TIM2_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI上
        TIM2_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;     //输入不分频
        TIM2_ICInitStructure.TIM_ICFilter = 0x00;//不滤波
    
        TIM_ICInit(TIM2, &TIM2_ICInitStructure);
   
    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;  
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;  
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; 
    NVIC_Init(&NVIC_InitStructure);   
    
    TIM_ITConfig(TIM2,TIM_IT_Update|TIM_IT_CC1,ENABLE);    

    TIM_ARRPreloadConfig(TIM2,ENABLE);
    TIM_DMACmd(TIM2,TIM_DMA_Update, ENABLE);              
    TIM_DMACmd(TIM2,TIM_DMA_CC1, ENABLE);  
    TIM_Cmd(TIM2,ENABLE);
}

https://blog.csdn.net/Britripe/article/details/83865599

void TIM2_IRQHandler(void)
{ 
        TIM2->CNT=0;//清楚CNT寄存器
        TIM2->SR=0;
}

void TIMDMA_Config(DMA_Channel_TypeDef* DMA_CHx,u32 cpar,u32 cmar,u16 cndtr)
{
     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);//打开DMA1时钟    
    
    DMA_DeInit(DMA_CHx);   
    DMA1_MEM_LEN=cndtr;
    DMA_InitStructure.DMA_PeripheralBaseAddr = cpar;//外设地址 
    DMA_InitStructure.DMA_MemoryBaseAddr = cmar;  //内存地址
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;  //传输方向外设到内存
    DMA_InitStructure.DMA_BufferSize = cndtr;  //传输数量
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外设地址不自增  
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  //内存地址自增
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;//外设数据大小为半字节
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord; //内存数据大小为半字节
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//重复
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;//高优先级
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;  
    DMA_Init(DMA_CHx, &DMA_InitStructure);  
          
} 

#define Lenth 12
u32 res=0;
u16 buffer[Lenth];
 int main(void)
 {    
     u32 sec;
     int i=0;
     NVIC_Configuration();     
     delay_init();                
     uart_init(115200);
     MYDMA_Config(DMA1_Channel5,(u32)&TIM2->CCR1,(u32)buffer,12);//传输方向TIM2->CCR1到buffer
     DMA_Cmd(DMA1_Channel5,ENABLE);//打开DMA通道15
     TIM2_Cap_Init(65535,0);
     printf("配置完成\n");
     while(1)
     {
         while(DMA_GetFlagStatus(DMA1_FLAG_TC5)==RESET);//等待DMA1通过5接收完成
         DMA_ClearFlag(DMA1_FLAG_TC5);
         TIM_Cmd(TIM5,DISABLE);
         for(i=0;i<12;i++)//数据量为12个加起来求平均
         {
             res+=buffer[i];
             buffer[i]=0;
         }
         printf("counts:%d\r\n",72000000/((res/12)+25));//转换为频率
         res=0;
         DMA_Cmd(DMA1_Channel5,ENABLE);
         TIM_Cmd(TIM5,ENABLE);
  }
 }

测试后中断中占用25个时钟周期 所以在计算加上去

 

该程序会将计算出的频率值通过串口发送至电脑,在1K到200K范围内达到千分之一精度

https://blog.csdn.net/shu_8708/article/details/73481305