STM32F103高级定时器输出PWM，波形滞后几秒

洛千叶提问时间：2017-6-14 16:00 /

STM32高级定时器修改CCR寄存器的值过几秒后占空比才改变怎么回事?以下是初始化程序
/* PWM信号电平跳变值 */
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef  TIM_OCInitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1 | RCC_APB2Periph_AFIO, ENABLE);

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 20000-1;
  TIM_TimeBaseStructure.TIM_Prescaler = 72-1; // 频率50Hz
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;    //比较输出使能
  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;  //选择互补输出比较状态

  TIM_OCInitStructure.TIM_Pulse = 1000; //设置了待装入捕获比较器的脉冲值
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //设置输出极性
  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;//开反向通道设置互补输出极性
  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;  //选择空闲状态下得非工作状态
  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset; //选择互补空闲状态下得非工作状态

  TIM_OC1Init(TIM1, &TIM_OCInitStructure);
  TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel2 */

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 1000;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;//开反向通道
  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

  TIM_OC2Init(TIM1, &TIM_OCInitStructure);
  TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel3 */

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 1000;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;//开反向通道
  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

  TIM_OC3Init(TIM1, &TIM_OCInitStructure);
  TIM_OC3PreloadConfig(TIM1, TIM_OCPreload_Enable);

//=========================================================
  TIM_ARRPreloadConfig(TIM1, ENABLE);

  /* TIM1 enable counter */
  TIM_Cmd(TIM1, ENABLE);
  TIM_CtrlPWMOutputs(TIM1, ENABLE);