【二叔科技】二叔测频率的测试

二叔科技

要测频率先得有一个频率源吧，不太准凑合用，用blink改造一下，大概20Hz的样子吧

1. /*
   
2.   Blink
   
3.   Turns on an LED on for one second, then off for one second, repeatedly.
   
4. 
   
5.   This example code is in the public domain.
   
6. */
   
7. 
   
8. // Pin 13 has an LED connected on most Arduino boards.
   
9. // give it a name:
   
10. int led = 13;
    
11. 
    
12. // the setup routine runs once when you press reset:
    
13. void setup() {               
    
14.   // initialize the digital pin as an output.
    
15.   pinMode(led, OUTPUT);     
    
16. }
    
17. 
    
18. // the loop routine runs over and over again forever:
    
19. void loop() {
    
20.   digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
    
21.   delay(25);               // wait for a second
    
22.   digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
    
23.   delay(25);               // wait for a second
    
24. }

复制代码

二叔科技

参考了一个卖传感器的商家的代码，当年二叔买这个传感器花了40+还有运费，一直扔着没用呢
http://detail.etao.com/18934469888.htm

1. int pin = 8;
   
2. unsigned long duration;
   
3. unsigned long starttime;
   
4. unsigned long sampletime_ms = 5000;
   
5. unsigned long lowpulseoccupancy = 0;
   
6. float ratio = 0;
   
7. 
   
8. void setup() {
   
9.   Serial.begin(9600);
   
10.   pinMode(pin,INPUT);
    
11.   starttime = millis();
    
12. }
    
13. 
    
14. void loop() {
    
15.   duration = pulseIn(pin, LOW);
    
16.   lowpulseoccupancy++;
    
17.   if ((millis()-starttime) > sampletime_ms)
    
18.   {
    
19.     ratio = lowpulseoccupancy*1000/sampletime_ms;
    
20.     Serial.print(ratio);
    
21.     Serial.println("Hz");
    
22.     lowpulseoccupancy = 0;
    
23.     starttime = millis();
    
24.   }
    
25. }

复制代码

二叔科技

测试结果20Hz蛮准确的


改到250Hz（不一定准），测得结果249Hz，这个结果可以接受啦

二叔科技

更专业的频率测试，不过二叔没看懂，来自饥渴工坊
http://www.geek-workshop.com/thread-3085-1-1.html