红外传感器测速，输出1个高低电平变化，但是Arduino读取多个

[tanghui0102]

大家好，新手求教。
想着arduino 红外避障模块识别白色贴纸，实现测速功能。
代码如下：

int LED = 13; // Use the onboard Uno
volatile float n = 0;
float dt;
float Speed;
float begin_time;
const byte interruptPin = 2;  //用2号引脚作为中断触发引脚


void setup() {
  pinMode(LED, OUTPUT);
  pinMode(interruptPin, INPUT);

    /*
   * 参数1
   interrupt  ——  中断源。0对应2号引脚；1对应3号引脚，依次类推。这里我们写的 0 ，即外部中断接数字引脚2号引脚。

   参数2
   function  ——  中断处理函数。即发生中断时，去做什么。这里我们让它发生中断时，做 n+=1。用来计数脉冲，电平变化的次数。

   参数3
   mode  ——  触发模式。触发模式有四种类型：LOW（低电平触发）、CHANGE（电平变化时触发）、RISING（低电平变为高电平时触发）、FALLING（高电平变为低电平时触发）。
   这里我们选择CHANGE（电平变化时触发），红外传感器敏感车轮上的白色反光条，车轮一圈均匀贴有6条反光条。车轮转一圈，传感器输出会有6次电平变化
  */
  attachInterrupt(digitalPinToInterrupt(interruptPin),count_pulse,FALLING);
  begin_time=millis();
  Serial.begin(9600);
}

void count_pulse(){
  Serial.println("I am being called");
  n += 1;
}

void loop() {
  dt=millis()-begin_time;
  /*每隔500ms输出一次转速，并重新开始计算下一个500ms的转速 */
  if(dt > 1000.0 ){
    //每一圈有6个脉冲，下面返回的值为rpm
    //delayMicroseconds(50);
    Serial.print("脉冲个数：");
    Serial.println(n);
    Serial.print("dt: ");
    Serial.println(dt);
    Serial.print("转速：");
    Speed =  (n/6) / (dt/60000);
    Serial.println(Speed);
    n = 0;
    begin_time = millis();
    Serial.flush();  // 确定都已经打印出去

  }
}

0:08:40.398 -> dt: 1001.00
10:08:40.398 -> 转速：0.00
10:08:41.358 -> 脉冲个数：0.00
10:08:41.398 -> dt: 1001.00
10:08:41.398 -> 转速：0.00
10:08:41.518 -> I am being called
10:08:41.518 -> I am being called
10:08:41.558 -> I am being called
10:08:41.558 -> I am being called
10:08:41.598 -> I am being called
10:08:41.638 -> I am being called
10:08:41.678 -> I am being called
10:08:41.678 -> I am being called
10:08:41.718 -> I am being called
10:08:41.718 -> I am being called
10:08:41.758 -> I am being called
10:08:41.758 -> I am being called
10:08:41.877 -> I am being called
10:08:41.917 -> I am being called
10:08:41.917 -> I am being called
10:08:41.957 -> I am being called
10:08:41.957 -> I am being called
10:08:42.198 -> I am being called
10:08:42.198 -> I am being called
10:08:42.198 -> I am being called
10:08:42.238 -> I am being called
10:08:42.238 -> I am being called
10:08:42.358 -> I am being called
10:08:42.398 -> I am being called
10:08:42.478 -> 脉冲个数：24.00
10:08:42.478 -> dt: 1001.00
10:08:42.518 -> 转速：239.76
10:08:42.557 -> I am being called
10:08:42.557 -> I am being called
10:08:42.597 -> I am being called
10:08:42.597 -> I am being called
10:08:42.637 -> I am being called
10:08:42.637 -> I am being called
10:08:42.677 -> I am being called
10:08:42.677 -> I am being called
10:08:42.717 -> I am being called
10:08:43.118 -> I am being called
10:08:43.158 -> I am being called
10:08:43.158 -> I am being called
10:08:43.198 -> I am being called
10:08:43.198 -> I am being called
10:08:43.238 -> I am being called
10:08:43.238 -> I am being called
10:08:43.278 -> I am being called
10:08:43.358 -> I am being called
10:08:43.398 -> I am being called
10:08:43.398 -> I am being called
10:08:43.438 -> I am being called
10:08:43.438 -> I am being called
10:08:43.478 -> I am being called
10:08:43.478 -> I am being called
10:08:43.518 -> I am being called
10:08:43.598 -> 脉冲个数：25.00
10:08:43.638 -> dt: 1001.00
10:08:43.638 -> 转速：249.75
10:08:43.678 -> I am being called
10:08:43.678 -> I am being called
10:08:43.718 -> I am being called
10:08:43.718 -> I am being called
10:08:43.758 -> I am being called
10:08:44.638 -> 脉冲个数：5.00
10:08:44.638 -> dt: 1001.00
10:08:44.678 -> 转速：49.95
10:08:45.638 -> 脉冲个数：0.00
10:08:45.678 -> dt: 1001.00
10:08:45.678 -> 转速：0.00
10:08:46.638 -> 脉冲个数：0.00

输出的脉冲数明显不对，且识别白色贴纸时，持续输出脉冲。
但是通过数据采集卡查看的波形，在车轮旋转一周识别的6个白色纸贴，正好输出6个脉冲。而arduino输出的脉冲个数如上所示，并不是高低电平变化而加1
请求大神指教，不胜感激！