一个基于mini2440的测试按键与led灯的测试程序

#include<stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include<errno.h>

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;
}