NRG 40 Anemometer: Using Freqmeasure.h to measure frequency on the arduino mega

Other Hardware Sensors
1

Trying to use the NRG 40 Anemometer to measure wind speed on the arduino mega. I currently have the signal going through a comparator, LM 324, to try and convert the sinewave to a square wave using a 5v source. I'm using Freqmeasure.h's Serial Output example which is as follows:

/* FreqMeasure - Example with serial output
 * http://www.pjrc.com/teensy/td_libs_FreqMeasure.html
 *
 * This example code is in the public domain.
 */
#include <FreqMeasure.h>

void setup() {
  Serial.begin(57600);
  FreqMeasure.begin();
}

double sum=0;
int count=0;

void loop() {
  if (FreqMeasure.available()) {
    // average several reading together
    sum = sum + FreqMeasure.read();
    count = count + 1;
    if (count > 30) {
      float frequency = FreqMeasure.countToFrequency(sum / count);
      Serial.println(frequency);
      sum = 0;
      count = 0;
    }
  }
}

Does the square wave need to be input to pin 49? does the voltage pk-pk matter? how "perfect" does the square wave need to be for the arduino to read it? the frequency is generally around 60 Hz with a pk-pk of ~600mV.

There is a simple equation for windspeed with frequency in Hz as the variable, so I just need to convert the voltage sinewave generated by the anemometer into a square wave that can be read by the arduino mega.

Thanks and if I'm missing any crucial information please let me know so I can provide it!!

2

a pk-pk of ~600mV

That probably won't work with an Arduino digital input.

Not enough information. Please read the "How to use this forum" post and follow the directions.

3

What pin would be the appropriate pin counting frequencies? what are the limitations of that signal (ie, does the signal need to be in a certain range of voltage, or a certain range of frequencies?)

On a side note, I did try to use the "how to use this forum". What sort of changes can i make to the post to make it easier for everyone?

thanks

4

What sort of changes can i make to the post to make it easier for everyone?

Post a circuit diagram (not Fritzing).

Post a link to the sensor.

For example, why is your input only varying by 600 mV when you have an amplifier? You need at least 3V variation for a digital input to register change.