STM32F107，PWM频率理论与实际差4.6倍

知之不知提问时间：2018-5-16 16:17 /

本帖最后由小水湾于 2018-5-16 16:20 编辑

static void PWM_GPIO_Config ( void )
{
  GPIO_InitTypeDef GPIO_InitStructure;

      RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

      GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_1;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

      GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

      GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
}
void PWM_Config (uint16_t ARR ,uint16_t CCR)
{
      TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
      TIM_OCInitTypeDef  TIM_OCInitStructure;

      RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3|RCC_APB1Periph_TIM4,ENABLE);

      TIM_DeInit(TIM3);
      TIM_DeInit(TIM4);
      TIM_TimeBaseStructure.TIM_Period=ARR;
      TIM_TimeBaseStructure.TIM_Prescaler= 7199;       //PSC
      TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;
      TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
      TIM_TimeBaseStructure.TIM_RepetitionCounter=0;

      TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
      TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

      TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
      TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
      TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

      TIM_OCInitStructure.TIM_Pulse = CCR;

      TIM_OC3Init(TIM3, &TIM_OCInitStructure);
      TIM_OC4Init(TIM3, &TIM_OCInitStructure);
      TIM_OC1Init(TIM4, &TIM_OCInitStructure);
      TIM_OC2Init(TIM4, &TIM_OCInitStructure);

      TIM_Cmd(TIM3, ENABLE);
      TIM_CtrlPWMOutputs(TIM3, ENABLE);
      TIM_Cmd(TIM4, ENABLE);
      TIM_CtrlPWMOutputs(TIM4, ENABLE);
}PWM_Config(1,1);
理论上PWM周期为100us,实际示波器量出来的是460us,
更改参数
PWM_Config(9999,5000);
理论上PWM周期为1s,实际示波器量出来的是2.3s,求解原因？？？
示波器量串口波特率38400bps是准的。