====== Button Interrupt example ======
  gcc -o wiring_isr wiring_isr.c -lwiringPi -lpthread
  ./wiring_isr
Push your SW1 on 16x2lcd board
<file c wiring_isr.c>
#include <stdio.h>                                                              
#include <wiringPi.h>                                                           
                                                                                
int volatile btnCounter;                                                        
                                                                                
void myInterrupt(void)                                                          
{                                                                               
        btnCounter++;                                                           
}                                                                               
                                                                                
int main(void)                                                                  
{                                                                               
        if (wiringPiSetup() < 0) {                                              
                printf("wiringPiSetup error.\n");                               
                return 1;                                                       
        }                                                                       
        if (wiringPiISR(5, INT_EDGE_FALLING, &myInterrupt) < 0) {               
                printf("wiringPiISR error.\n");                                 
                return 1;                                                       
        }                                                                       
                                                                                
        while(1) {                                                              
                printf("%d\n", btnCounter);                                     
                delay(1000);                                                    
        }                                                                       
                                                                                
        return 0;                                                               
}
</file>