void TIM3_PWM_Init(u16 arr,u16 psc)
{
    GPIO_InitTypeDef GPIO_InitStructure;
     
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitSture;
    TIM_OCInitTypeDef TIM_OCInitTypeSture;
     
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);  
    GPIO_PinRemapConfig(GPIO_FullRemap_TIM3,ENABLE);
     
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//¸´ÓÃÍÆÍì
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;//TIM3_CH3
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC,&GPIO_InitStructure);
  
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
   
    TIM_TimeBaseInitSture.TIM_Period = arr;                        
    TIM_TimeBaseInitSture.TIM_Prescaler = psc;  
    TIM_TimeBaseInitSture.TIM_CounterMode = TIM_CounterMode_Up;      
    TIM_TimeBaseInitSture.TIM_ClockDivision = 0;
    TIM_TimeBaseInit(TIM3,&TIM_TimeBaseInitSture);
   
    TIM_OCInitTypeSture.TIM_OCMode = TIM_OCMode_PWM2;
    TIM_OCInitTypeSture.TIM_Pulse = 0;
    TIM_OCInitTypeSture.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCInitTypeSture.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OC3Init(TIM3,&TIM_OCInitTypeSture);
   
    TIM_CtrlPWMOutputs(TIM3,ENABLE);  
    TIM_OC3PreloadConfig(TIM3,TIM_OCPreload_Enable);  
    TIM_ARRPreloadConfig(TIM3, ENABLE);
   
    TIM_Cmd(TIM3,ENABLE);
}
主程序：
main
{
    delay_init();
    TIM3_PWM_Init(899,0);
    while(1)
   {
    TIM3_PWM_Init(300,240); //1000hz
    TIM_SetCompare1(TIM3,150);//
    delay_ms(500);

   }
}