void PWM_TIM1(uint16_t arr,uint16_t psc)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);    //定時器TIM1時鐘使能
    TIM_DeInit(TIM1);

   //設定在下一個更新事件裝入活動的自動重灌載暫存器週期的值
     TIM_TimeBaseStructure.TIM_Period =arr;     
    //設定用來作為TIMx時鐘頻率出書的預分頻值
     TIM_TimeBaseStructure.TIM_Prescaler =psc;              
 

    //設定時鐘分割
     TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    //設定計數模式    
     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
     //初始化引數
     TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);               

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_2);   //TIM1channel2
 

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_2);  //TIM1channel3
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA,ENABLE);
//PA9
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; 
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; 
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; 
    GPIO_InitStructure.GPIO
 
_PuPd = GPIO_PuPd_NOPULL; 
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; 
    GPIO_Init(GPIOA, &GPIO_InitStructure); 

//PA10
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; 
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; 
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; 
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; 
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; 
    GPIO_Init(GPIOA, &GPIO_InitStructure); 


    //TIM1的channel2  
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; 
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 
    TIM_OC2Init(TIM1, &TIM_OCInitStructure);  

      //TIM1的channel3
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; 
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 
    TIM_OC3Init(TIM1, &TIM_OCInitStructure);

    TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Enable);  
    TIM_OC3PreloadConfig(TIM1, TIM_OCPreload_Enable);      

     TIM_Cmd(TIM1, ENABLE);  //使能TIM1


}



int main()
{
        PWM_TIM1(999,1);//頻率為：48MHZ/(999+1)/(1+1)=24KHZ
        TIM_SetCompare2(TIM1,499);  //佔空比為50%方波
        PWM_TIM1(399,1);//頻率為：48MHZ/(399+1)/(1+1)=
        TIM_SetCompare3(TIM1,199);  //佔空比為50%方波



}