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Susiskaičiuoja kiek kartų įvykis atsitiko per sekundę

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <wiringPi.h>

#define BUTTON_PIN 2 // Use GPIO Pin 17

volatile int eventCounter = 0; // the event counter

// -------------------------------------------------------------------------
// myInterrupt:  called every time an event occurs
void myInterrupt(void) {
   eventCounter++;
}
// -------------------------------------------------------------------------
int main(void) {
  // sets up the wiringPi library
  if (wiringPiSetupGpio  () < 0) {
      fprintf (stderr, "Unable to setup wiringPi: %s\n", strerror (errno));
      return 1;
  }

  // set Pin generate an interrupt on high-to-low transitions
  // and attach myInterrupt() to the interrupt
  if ( wiringPiISR (BUTTON_PIN, INT_EDGE_FALLING, &myInterrupt) < 0 ) {
      fprintf (stderr, "Unable to setup ISR: %s\n", strerror (errno));
      return 1;
  }

  // display counter value every second.
  while ( 1 ) {
    printf( "%d\n", eventCounter );
    eventCounter = 0;
    delay( 1000 ); // wait 1 second
  }

  return 0;
}