怎么用stm32测量输出信号的脉冲个数和频率？

874357539 · 发表于 2012-5-26 11:44:10

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rakcart · 发表于 2012-5-26 11:50:17

外部中断+定时器

bob · 发表于 2012-5-26 11:56:01

定时器输入捕获！

874357539 · 发表于 2012-5-26 18:12:57

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tianyuhui · 发表于 2012-5-26 18:31:26

大致过程如下：频率不知到太大会不会有问题，低频下测试可以....
1、void EXIT_Configuration(void)
{
      /* 定义EXIT初始化结构体 EXTI_InitStructure */
      EXTI_InitTypeDef EXTI_InitStructure;

      /* 设置外部中断10,11,12通道在上升沿时触发中断 */
      EXTI_InitStructure.EXTI_Line = EXTI_Line10 | EXTI_Line11 | EXTI_Line12;
      EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
      EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; //三种触发方式可选
      EXTI_InitStructure.EXTI_LineCmd = ENABLE;
      EXTI_Init(&EXTI_InitStructure);
}
2.  中端配置 ......
3.  中断中记录脉冲
void EXTI15_10_IRQHandler(void)
{
               /*----- 外部中断10:记录脉冲数 -----*/
      if(EXTI_GetITStatus(EXTI_Line10) != RESET)
      {
               printf("EXIT10 IRQHandler Enter.\r\n");       //串口调试
               g_PulseCnt++;
               EXTI_ClearFlag(EXTI_Line10);
      }
            //...
}
4.频率计算: 定时器或systick产生100ms标志
//...............
if(g_100msFlag == 1)
{
      g_100msFlag = 0；
   freq = g_PulseCnt*10;
      g_PulseCnt = 0；
}

823032003 · 发表于 2012-5-26 19:08:48

定时器输入捕获的基本功能

Forest_liu · 发表于 2012-5-26 19:11:12

可以用定时器的捕获，上升沿触发或下降沿触发都可以。

millwood0 · 发表于 2012-5-26 19:32:58

if the pulse train is of high frequencies, use a counter to count it within a given period of time. This approach is typically good for >10Mhz.

bsz84 · 发表于 2012-5-26 20:34:29

LS:
在低频下如何测量脉冲？

millwood0 · 发表于 2012-5-26 22:29:20

在低频下如何测量脉冲？

it depends on how slow your 低频 signal is and what your requirements are.

You can still use the same approach I outlined earlier for slow speed signals. However, if your signal is very slow (in terms of Hz), or you require higher precision in those cases, you may use capture, or external int - to time the duration between two interrupts.

It goes something like this:

1) set the timer to count cpu frequency. don't start yet.
2) when the 1st pulse arrives, turn on the timer and start counting.
3) when the 2nd pulse arrives, turn off the timer and the count in the timer + cpu frequency tells you how much time has elapsed -> you know the external pulse's period / frequency.

danju · 发表于 2012-5-27 00:02:41

用stm32测量输出信号的脉冲个数和频率，既然是输出信号，发了多少脉冲个数CPU是可以知道的吧，输出时计数会方便些吧