STM32输出PWM波遇到一些问题

只看该作者 · 2015-11-25 14:45

本帖最后由 Anthonybrave 于 2015-11-25 15:32 编辑

用Tim3输出PWM波。使用PA6、PA7、PB0、PB1。能够发出占空比不同的方波。
代码如下：
void TIM3_PWM_Init(void)
{
      GPIO_InitTypeDef       GPIO_InitStructure;
      TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
      TIM_OCInitTypeDef       TIM_OCInitStructure;

//       RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3|RCC_APB2Periph_GPIOA, ENABLE); //使能TIM3时钟，GPIOA时钟
      RCC_APB1PeriphClockCmd (RCC_APB1Periph_TIM3,ENABLE);
      RCC_APB2PeriphClockCmd (RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB,ENABLE);

GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

  /*GPIOB Configuration: TIM3 channel 3 and 4 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0 | GPIO_Pin_1;
GPIO_Init(GPIOB, &GPIO_InitStructure);

      /* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 999;
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 750;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
  TIM_OC1Init(TIM3, &TIM_OCInitStructure);
  TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel2 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 500;
  TIM_OC2Init(TIM3, &TIM_OCInitStructure);
  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel3 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 250;
  TIM_OC3Init(TIM3, &TIM_OCInitStructure);
  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel4 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 100;
  TIM_OC4Init(TIM3, &TIM_OCInitStructure);
  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM3, ENABLE);
  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);
}

问题如下：(已解决) 另外有个问题请大神看下三楼
1、使用其他IO口，比如PA4、PA5或者PB6、PB7，在IO口处检测不到方波.
2、使用其他定时器，比如Tim2，就检测不到方波。