STM32 外部脉冲计数值不正确，求解

fangxiaoyanzhou

使用的TIM4-CH2（PD.13）产生10K的PWM波，接入TIM1-ETR(PE.7)，1ms后读取计数器的值，读的值与实际不符合，实际波形个数如图2所示

源码如下：

EXTI_InitTypeDef EXTI_InitStructure;

TIM_OCInitTypeDef  TIM_OCInitStructure;

void RCC_Configuration(void);

void GPIO_Configuration(void);

void NVIC_Configuration(void);

void Delay(__IO uint32_t nCount);

void tim1_confi(void);

void tim4_confi(void);

u16 Count_pulse(u16 c);  

u16 counter=0;

int main(void)

{ 

// u8 i=0; 

  /* System Clocks Configuration */

  RCC_Configuration();

       

  /* NVIC configuration */

  NVIC_Configuration();

    

  /* Configure the GPIO ports */

  GPIO_Configuration();

  /*Configure tim1*/

  tim1_confi();

  tim4_confi();

  while (1)

  {

Delay(10000);  //1ms

TIM_Cmd(TIM1, ENABLE);

TIM_Cmd(TIM4, ENABLE);

Delay(10000);  //1ms

TIM_Cmd(TIM4, DISABLE);

TIM_Cmd(TIM1, DISABLE);

counter=TIM_GetCounter(TIM1);

//      for(i = 0; i < 4; i ++) 

//  {

//  GPIO_SetBits(GPIOE, GPIO_Pin_8);

//  Delay(100); //15US

//  GPIO_ResetBits(GPIOE, GPIO_Pin_8);

//  Delay(100);

//  }

//  //counter=TIM_GetCounter(TIM1);

//  counter=TIM1->CNT;

  }

}

void Delay(__IO uint32_t nCount)   //0.1us

{

  for(; nCount != 0; nCount--);

}

void RCC_Configuration(void)

{

 

  SystemInit();

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE  | RCC_APB2Periph_AFIO, ENABLE);

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);  //使能定时器TIM1时钟

}

void GPIO_Configuration(void)

{

 GPIO_InitTypeDef  GPIO_InitStructure;

 

 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE, ENABLE); //使能PE端口时钟

 RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);  //使能定时器TIM1时钟

 GPIO_PinRemapConfig (GPIO_FullRemap_TIM1 ,ENABLE );  //重映射

 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; // 端口配置

 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //输入

 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO口速度为50MHz

 GPIO_Init(GPIOE, &GPIO_InitStructure); //根据设定参数初始化GPIOE.7

 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8; //PE.8 端口配置

 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //推挽输出

 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO口速度为50MHz

 GPIO_Init(GPIOE, &GPIO_InitStructure); //根据设定参数初始化GPIOE.8

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE); //使能PD端口时钟

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);  //使能定时器TIM4时钟

  GPIO_PinRemapConfig (GPIO_Remap_TIM4  ,ENABLE );  //重映射

  GPIO_InitStructure.GPIO_Pin=GPIO_Pin_13 ;

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; 

  GPIO_Init(GPIOD, &GPIO_InitStructure); 

}

 void tim1_confi(void)  //TIM1初始化

 {

  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

    TIM_DeInit( TIM1 ) ;

  /* Time Base configuration */

TIM_TimeBaseStructure.TIM_Period = 0XFFFF; //

TIM_TimeBaseStructure.TIM_Prescaler = 0;

  TIM_TimeBaseStructure.TIM_ClockDivision = 0;

  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); 

/* TIM1-ETR Configuration */

  TIM_ETRClockMode2Config (TIM1,TIM_ExtTRGPSC_OFF,TIM_ExtTRGPolarity_NonInverted,0);

TIM_SetCounter( TIM1,0) ; //从零计数

TIM_Cmd(TIM1, DISABLE); //使能打开

 }

  void tim4_confi(void)  //TIM4初始化

  {

 // TIM4-CH2基本计数器设置（设置PWM频率）

// 频率=TIM1_CLK/(ARR+1)

     TIM_TimeBaseInitTypeDef TIM_BaseInitStructure;

    TIM_DeInit( TIM4 ) ;

    TIM_BaseInitStructure.TIM_Period = 100;  // 确定T=0.1ms

    TIM_BaseInitStructure.TIM_Prescaler = 72-1;  

    TIM_BaseInitStructure.TIM_ClockDivision = 0;

    TIM_BaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;

    TIM_BaseInitStructure.TIM_RepetitionCounter = 0;

    TIM_TimeBaseInit(TIM4, &TIM_BaseInitStructure);

 //启用ARR的影子寄存器（直到产生更新事件才更改设置）

TIM_ARRPreloadConfig(TIM4, ENABLE);

//TIM4_OC2模块设置

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;

TIM_OCInitStructure.TIM_Pulse = 50;

TIM_OC2Init(TIM4, &TIM_OCInitStructure);

TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);

//TIM3开启

TIM_Cmd(TIM4, DISABLE);

//TIM1_OC通道输出PWM（一定要加）

TIM_CtrlPWMOutputs(TIM4, ENABLE);

  

  }

u16 Count_pulse(u16 c) 

{

TIM_Cmd(TIM1, ENABLE);

TIM_Cmd(TIM4, ENABLE);

Delay(1000);  //1ms

TIM_Cmd(TIM1, DISABLE);

TIM_Cmd(TIM4, DISABLE);

   counter=TIM_GetCounter(TIM1);  //只能读出最终值，采样的时钟要比输入信号快。

   c= counter;

  return c;

}

#ifdef  USE_FULL_ASSERT

void assert_failed(uint8_t* file, uint32_t line)

{ 

  while (1)

  {

  }

}

#endif

使用红色部分产生20us方波，然后连接PE.7作为输入，计数结果正常。。请问是不是对输入脉冲的频率有要求？

xiaoyan

回复【楼主位】fangxiaoyanzhou:
---------------------------------
那你降低频率看看。

fangxiaoyanzhou

回复【2楼】xiaoyan:
---------------------------------
楼主，用定时器输出的方波周期为0.1ms,使用延时产生的方波周期为20us,输入方波的频率已经降低了。。

fangxiaoyanzhou

回复【2楼】xiaoyan:
---------------------------------
http://www.amobbs.com/thread-4146690-1-1.html，参照这个，应该是正常的。。