STM32的PWM输入模式问题请教

woshilee

STM32的PWM输入模式问题请教 [复制链接]

#include "stm32f10x.h"
__IO uint32_t IC2Value = 0;
__IO uint32_t IC1Value = 0;
__IO uint16_t DutyCycle = 0;
__IO uint32_t Frequency = 0;
__IO uint16_t i=0,j=0;
TIM_ICInitTypeDef  TIM_ICInitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;

void RCC_Configuration(void)
{
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
}


void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  /* TIM3 channel 2 pin (PA.07) configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

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


void NVIC_Configuration(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}


void TIM_OC_Configuration(void)
{
  //配置以后输出PWM的频率是100Hz
  TIM_TimeBaseStructure.TIM_Period =100-1;
  TIM_TimeBaseStructure.TIM_Prescaler =  7199;//分频至1M
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 50-1;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC1Init(TIM2, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);
        TIM_Cmd(TIM2, ENABLE);
}
void TIM_IC_Configuration(void)
{
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;

  TIM_PWMIConfig(TIM3, &TIM_ICInitStructure);//同时配置了通道1和通道2，输入1和输入2同事映射到了通道2

  /* Select the TIM3 Input Trigger: TI2FP2 */
  TIM_SelectInputTrigger(TIM3, TIM_TS_TI2FP2);

  /* Select the slave Mode: Reset Mode */
  TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);

  /* Enable the Master/Slave Mode */
  TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable);

  /* TIM enable counter */
  TIM_Cmd(TIM3, ENABLE);

  /* Enable the CC2 Interrupt Request */
  TIM_ITConfig(TIM3, TIM_IT_CC2, ENABLE);
//         TIM_ITConfig(TIM3, TIM_IT_CC1, ENABLE);
//   TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);
}



int main(void)
{

  RCC_Configuration();

  NVIC_Configuration();

  GPIO_Configuration();
  TIM_OC_Configuration();
  TIM_IC_Configuration();

  while (1);
}


void TIM3_IRQHandler(void)
{
  /* Clear TIM3 Capture compare interrupt pending bit */
  TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);

  /* Get the Input Capture value */
  IC2Value = TIM_GetCapture2(TIM3);

  if (IC2Value != 0)
  {
    /* Duty cycle computation */
    DutyCycle = (TIM_GetCapture1(TIM3) * 100) / IC2Value;

    /* Frequency computation */
    Frequency = SystemCoreClock / IC2Value;
  }
  else
  {
    DutyCycle = 0;
    Frequency = 0;
  }
}
这是按照库里边的例程改的，可以测频率较大的频率，频率小的话定时器2的计数器就会溢出，就无法准确测量频率了，哪位高人可以指点一下怎么做？

  if (IC2Value != 0)这个判断是什么意思？是第一次触发的时候计数器IC2Value清零吗？我加了断点发现不会进入else分支
谢了

huo_hu

TIM_TimeBaseStructure.TIM_ClockDivision = 0;改这个使用更多的分频.
!=0的条件可以去抖.

woshilee

huo_hu 发表于 2014-11-13 20:57
TIM_TimeBaseStructure.TIM_ClockDivision = 0;改这个使用更多的分频.
!=0的条件可以去抖.

我分频之后得到的数据就一点意义没有了，是错的，不知道怎么回事，无论是分频还是预分频
比如 TIM_TimeBaseStructure.TIM_ClockDivision = 2;
时钟成了36MHz
得到的结果没有参考意义了，很大

huo_hu

=1,数值应该是原来的2倍