/* square wave beeper for loudspeaker attached to LED 

usleep has a minimum delay that is too long - so simple FOR loops are used 

tested with LED 0, the power led - this one is earthed 
- connect an amplifier to the positive end of the diode */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <stdio.h>
#include <sys/ioctl.h>
#include <errno.h>


int main(int argc, char** argv)
{

	int	led_fd 			= 0;
	int		f_status 	= 1;
	int		i;
	int		j;
	int led_nr;
	int ontime; /* these are microseconds */
	int offtime;
	int loops;
	int count; /* this counts up to value of loops*/
	int k; /* for the delay loops - usleep has a minimum delay! */
	


 if (argc != 5)
 {
  printf("Error. usage: %s lednumber ontime offtime loops\n", argv[0]);
  f_status = 0;             
 }

/* led_nr is the first number after the program name */
	led_nr = atoi(argv[1]);
/* set the  pulse on time (ontime)*/
	ontime = atoi(argv[2]);
/* set the  base line off time (offtime)*/
	offtime = atoi(argv[3]);
/* set the  total number of pulses to be output within the beep */
	loops = atoi(argv[4]);


for (count = 1;count <= loops;count = count + 1)
   {
	led_fd = open("/dev/gpio0",O_RDWR);
	if (led_fd == -1)
	{
		printf("fopen failed, errno %d\n", errno);
		f_status = 0;
	}
	if (f_status)
	{

            /* positive pulse */
            ioctl(led_fd, 0, led_nr);
		for (k = 1;k <= ontime;k = k + 1)
		{
		/* put something here to take time? */
		}

            /* zero volts time */
            ioctl(led_fd, 1, led_nr);
		for (k = 1;k <= offtime;k = k + 1)
		{
		/* put something here to take time? */
		}

		close (led_fd);
	}
   }
	return 0;
}