unsigned int Get_Timer_Tick_TIM2(float freq){
         unsigned int tick;
         RCC_ClocksTypeDef  RCC_Clocks;
         
         RCC_GetClocksFreq(&RCC_Clocks);
         
         if(freq<80) freq=80;//限制频率的低限值！
        
         tick=RCC_Clocks.PCLK1_Frequency/freq;//得到间隔常数！1000 是秒的转换，100是分频系数！
        //tick /=2;
         //if(tick<9) tick=9;
         
         return tick+(signed char)Mp1.Fr;  //DMA操作要8个时钟周期！！
}


Mp1这个结构体是干啥的？
有工程吗？

还有这个
void TIM2_Config(unsigned int cnt){
         TIM_TimeBaseInitTypeDef   TIM_TimeBaseStructure;
         
         RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
         TIM_DeInit(TIM2);

    /* TIM2 Configuration ------------------------------------------------------*/
    /* TIM3CLK = 72 MHz, Prescaler = 0, TIM3 counter clock = 72 MHz */
    /* Time base configuration */
    TIM_TimeBaseStructure.TIM_Period = cnt;         
    TIM_TimeBaseStructure.TIM_Prescaler = 0;      
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;   
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;   
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    /* Input Capture Mode configuration: Channel1 */        
/* TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;         
    TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    TIM_ICInitStructure.TIM_ICFilter = 0;
    TIM_ICInit(TIM3, &TIM_ICInitStructure);*/
     
    /* Enable TIM2 DMA */
    TIM_DMACmd(TIM2, TIM_DMA_Update, ENABLE);//TIM_DMA_CC1

    /* Enable TIM2 counter */
    TIM_Cmd(TIM2, DISABLE);
}

TIM3相关的初始化是不是多余的