I'll show you how to control USB Web Relays via USB Joystick
Needed
1 RaspberryPI
1 USB joystick
USB 485 relay
recommend install Raspbian
C Code
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/joystick.h>
#define JOY_DEV "/dev/input/js0"
int main()
{
int f;
int joy_fd, *axis=NULL, num_of_axis=0, num_of_buttons=0, x;
char *button=NULL, name_of_joystick[80];
struct js_event js;
if( ( joy_fd = open( JOY_DEV , O_RDONLY)) == -1 )
{
printf( "Couldn't open joystick\n" );
return -1;
}
ioctl( joy_fd, JSIOCGAXES, &num_of_axis );
ioctl( joy_fd, JSIOCGBUTTONS, &num_of_buttons );
ioctl( joy_fd, JSIOCGNAME(80), &name_of_joystick );
axis = (int *) calloc( num_of_axis, sizeof( int ) );
button = (char *) calloc( num_of_buttons, sizeof( char ) );
printf("Joystick detected: %s\n\t%d axis\n\t%d buttons\n\n"
, name_of_joystick
, num_of_axis
, num_of_buttons );
fcntl( joy_fd, F_SETFL, O_NONBLOCK ); /* use non-blocking mode */
while( 1 ) /* infinite loop */
{
/* read the joystick state */
read(joy_fd, &js, sizeof(struct js_event));
/* see what to do with the event */
switch (js.type & ~JS_EVENT_INIT)
{
case JS_EVENT_AXIS:
axis [ js.number ] = js.value;
break;
case JS_EVENT_BUTTON:
button [ js.number ] = js.value;
break;
}
/* print the results */
printf( "X: %6d Y: %6d ", axis[0], axis[1] );
if( num_of_axis > 2 )
printf("Z: %6d ", axis[2] );
if( num_of_axis > 3 )
printf("R: %6d ", axis[3] );
for( x=0 ; x<num_of_buttons ; ++x )
printf("B%d: %d ", x, button[x] );
if(button[0] > 0) {f = popen("exec bash myscript.bash", "r");}
printf(" \r");
fflush(stdout);
}
close( joy_fd ); /* too bad we never get here */
return 0;
}
