e.c

// e.c
//
// Example program for bcm2835 library
// Event detection of an input pin
//
// After installing bcm2835, you can build this
// with something like:
// gcc -o e e.c -l bcm2835 -l rt
// sudo ./e
//
// Or you can test it before installing with:
// gcc -o event -I ../../src ../../src/bcm2835.c event.c
// sudo ./event
//
// Author: Mike McCauley
// Copyright (C) 2011 Mike McCauley
// $Id: RF22.h,v 1.21 2012/05/30 01:51:25 mikem Exp $
#include <bcm2835.h>
#include <stdio.h>
// Input on RPi pin GPIO 13
#define PIN RPI_GPIO_P1_13
int main(int argc, char **argv)
{
    // If you call this, it will not actually access the GPIO
    // Use for testing
//    bcm2835_set_debug(1);
    if (!bcm2835_init())
        return 1;
    // Set RPI pin P1-13 to be an input
    bcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_INPT);
    //  with a pullup
    bcm2835_gpio_set_pud(PIN, BCM2835_GPIO_PUD_UP);
    // And a low detect enable
    bcm2835_gpio_len(PIN);
    while (1)
    {
        if (bcm2835_gpio_eds(PIN))
        {
            // Now clear the eds flag by setting it to 1
            bcm2835_gpio_set_eds(PIN);
            printf("low event detect for pin 13\n");
        }
        // wait a bit
        delay(500);
    }
    bcm2835_close();
    return 0;
}