STM32F103的pwm输出

只看该作者 · 2015-12-16 20:13

刚学stm32f103的板子，就是按照原子的程序改了个IO口，但是好像PA7的没有PWM输出，我也是用TIM3_CH2来控制PA7的灯，毫无反应，灯都不亮，求大神指教void TIM3_Int_Init(u16 arr,u16 psc)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
      NVIC_InitTypeDef NVIC_InitStructure;

      RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

      TIM_TimeBaseStructure.TIM_Period = arr;
      TIM_TimeBaseStructure.TIM_Prescaler =psc;
      TIM_TimeBaseStructure.TIM_ClockDivision = 0;
      TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
      TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

      TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE );
      NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
      NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
      NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
      NVIC_Init(&NVIC_InitStructure);
      TIM_Cmd(TIM3, ENABLE);

}void TIM3_IRQHandler(void) //TIM3ÖÐ¶Ï
{
      if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
            {
            TIM_ClearITPendingBit(TIM3, TIM_IT_Update  );

            }
}

void TIM3_PWM_Init(u16 arr,u16 psc)
{
      GPIO_InitTypeDef GPIO_InitStructure;
      TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
      TIM_OCInitTypeDef  TIM_OCInitStructure;
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

      //ÉèÖÃ¸ÃÒý½ÅÎª¸´ÓÃÊä³ö¹¦ÄÜ,Êä³öTIM3 CH2µÄPWMÂö³å²¨ÐÎ GPIOB.5
      GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_Init(GPIOA, &GPIO_InitStructure)

//³õÊ¼»¯TIM3
      TIM_TimeBaseStructure.TIM_Period = arr;
      TIM_TimeBaseStructure.TIM_Prescaler =psc;
      TIM_TimeBaseStructure.TIM_ClockDivision = 0;
      TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
      TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

      //³õÊ¼»¯TIM3 Channel2 PWMÄ£Ê½
      TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
      TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
      TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
      TIM_OC2Init(TIM3, &TIM_OCInitStructure);

      TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

      TIM_Cmd(TIM3, ENABLE);
}
主程序是这样的
int main(void)
{

      u16 led0pwmval=0;

      u8 dir=1;
      delay_init();
  JTAG_Set(JTAG_SWD_DISABLE); //¹Ø±ÕJTAG); //¹Ø±ÕJTAG
      NVIC_Configuration();
      uart_init(9600);
      LED_Init();
      TIM3_PWM_Init(899,0);
  while(1)
      {
delay_ms(10);
      if(dir)
      {
led0pwmval++;

}
      else
      {led0pwmval--;

}
      if(led0pwmval>300) dir=0;
      if(led0pwmval==0) dir=1;
      TIM_SetCompare2(TIM3,led0pwmval);

  }
}
才学stm32,求帮忙，弄了好两天了，非常感谢