跪求，我的STM32f1不能输出PWM

skqepk 提问时间：2018-7-16 23:47 /

我是初学者，现在用STM32F1.用定时器1，PA8的口输出PWM，但怎样配置都不能有效果输出，求大神支招

int main(void)
{
      u16 led0pwmval=0;
      u8 dir=1;
      Stm32_Clock_Init(9); //系统时钟设置
      delay_init(72);          //延时初始化
      uart_init(72,9600);  //串口初始化
      LED_Init();                         //初始化与LED连接的硬件接口
      TIM1_PWM_Init(899,0);//不分频。PWM频率=72000/(899+1)=80Khz
         while(1)
      {
            delay_ms(10);
            if(dir)led0pwmval++;
            else led0pwmval--;
            if(led0pwmval>300)dir=0;
            if(led0pwmval==0)dir=1;
            LED0_PWM_VAL=led0pwmval;

      }
}

void LED_Init(void)
{

      GPIO_InitTypeDef GPIO_InitStruct;

      RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA
                                                |RCC_APB2Periph_GPIOD
                           |RCC_APB2Periph_GPIOC
                           |RCC_APB2Periph_AFIO, ENABLE);



      GPIO_InitStruct.GPIO_Mode=GPIO_Mode_AF_PP;                //推挽输出
      GPIO_InitStruct.GPIO_Pin=GPIO_Pin_8;                      //选择P8口
      GPIO_InitStruct.GPIO_Speed=GPIO_Speed_50MHz;       //50Mhz

      GPIO_Init(GPIOA,&GPIO_InitStruct);

}

void time_Init(void)
{

      TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStrue;
      TIM_OCInitTypeDef TIM_OCInitStrue;

      RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE); //1


      TIM_TimeBaseInitStrue.TIM_CounterMode=TIM_CounterMode_Up;
      TIM_TimeBaseInitStrue.TIM_Period       =1000;             //重装载值
      TIM_TimeBaseInitStrue.TIM_Prescaler =72;             //预分频
      TIM_TimeBaseInitStrue.TIM_ClockDivision= TIM_CKD_DIV1;
      TIM_TimeBaseInit(TIM1,&TIM_TimeBaseInitStrue);

//       TIM_OCInitStrue.TIM_OCIdleState
      TIM_OCInitStrue.TIM_OCMode=TIM_OCMode_PWM2;
//       TIM_OCInitStrue.TIM_OCNIdleState
//       TIM_OCInitStrue.TIM_OCNPolarity
      TIM_OCInitStrue.TIM_OCPolarity=TIM_OCPolarity_High;       //输出极性
//       TIM_OCInitStrue.TIM_OutputNState
      TIM_OCInitStrue.TIM_OutputState=TIM_OutputState_Enable;
      TIM_OCInitStrue.TIM_Pulse=300;
      TIM_OC1Init(TIM1,&TIM_OCInitStrue);

      TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable); //预重装载值（可用可不用）

      TIM_Cmd(TIM1,ENABLE);                      //使能定时器

      TIM_CtrlPWMOutputs(TIM1,ENABLE);

      TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);

      TIM_ARRPreloadConfig(TIM1, ENABLE);


}