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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

pio button

Hi,

I try to use pio button.

Typing cat /dev/button I can see that the button drivers are working.

How can I use the functions in altera_pio_button.c to make my own uClinux app?

thanks

stepa

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    21 years ago

    I think the following code works... it's been awhile since I looked at it. I think there may have been an issue with shutting down the app properly but it should give you some good ideas as to how to proceed. 

    #include <stdio.h># include <unistd.h># include <fcntl.h># include <stdlib.h> 
/* open /dev/button device for blocked reading
 * whenever button is pressed,
 *   display number of times button was pressed since startup
 */
int
main (int argc, char* argv)
{
  int fd;
  char path = "/dev/button";
  
  int numclicks = 0;
  char buf;
  
  fd = open (path, O_RDONLY);
  
  if (fd < 0) {
    /* error occurred */
    perror ("open");
    exit (EXIT_FAILURE);
  } else {
    printf ("opened %s\n", path);
  }
  
  /* file is now open for reading... do your stuff... */
  while (read (fd, buf, 1) != 0) {
    if (buf == &#39;1&#39;) {
      numclicks += 1;
    }
    printf ("The button has been pushed %d times.\n", numclicks);
  }
  
  if (close (fd) < 0) {
    perror ("close");
    exit (EXIT_FAILURE);
  } else {
    printf ("closed %s\n", path);
  }
  
  exit (EXIT_SUCCESS);
}