按键测试程序

#include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 
int main(void)
 {
  int buttons_fd,led_fd;
  char buttons[6] = {'0', '0', '0', '0', '0','0'};
 
 buttons_fd =open("/dev/buttons", 0);
  if (buttons_fd < 0) {
   perror("open devicebuttons");
   exit(1);
  }
  led_fd = open("/dev/leds", 0);
  if(led_fd < 0) {
   perror("open deviceleds");
   exit(1);
  }
  for (;;) {
   char current_buttons[6];
   int count_of_changed_key;
   int i;
   if (read(buttons_fd,current_buttons, sizeof current_buttons) != sizeof current_buttons){
    perror("readbuttons:");
    exit(1);
   }
 
  for (i = 0,count_of_changed_key = 0; i < sizeof buttons /sizeof buttons[0]; i++) {
    if(buttons[i] != current_buttons[i]) {
     buttons[i]= current_buttons[i];
     printf("%skey%d is %s", count_of_changed_key? ", ": "", i+1, buttons[i] == '0' ?"up" : "down");
     //按下时亮，松开时灭，注意这里由于mini2440开发板只有4个灯，而按键有6个，所以只能按前四个键才能执行，否则按其他键会报错的。//
 
    if(buttons[i]!='0')
 
     ioctl(led_fd,1,i);
     else
      ioctl(led_fd,0,i);
     count_of_changed_key++;
    }
   }
   if (count_of_changed_key){
    printf("\n");
   }
   
   
  }
  close(buttons_fd);
  return 0;
 }