anemometer - frequency library

Other Hardware Sensors
3

here

#include <FreqCounter.h>

void setup() {
Serial.begin(57600); // connect to the serial port
Serial.println("Frequency Counter");
}

long int frq;
void loop() {

FreqCounter::f_comp= 8; // Set compensation to 12
FreqCounter::start(100); // Start counting with gatetime of 100ms
while (FreqCounter::f_ready == 0) // wait until counter ready

frq=FreqCounter::f_freq; // read result
Serial.println(frq); // print result
delay(20);
}

http://interface.khm.de/index.php/lab/experiments/arduino-frequency-counter-library/

thank you for the answer !