How to get USB stick free size in FAT file system?

[BParh.1]

Hi,

I am working to make application of USB host. At initial stage, I need to read how big is the free size of attached USB stick using the FAT file system middle ware. Can someone give me some pointer which FAT system interface I can use? I know how to mount and dismount, but not sure how to get this USB stick free size.

[KnarfB · Accepted solution]

f_getfree ? http://elm-chan.org/fsw/ff/doc/getfree.html

hth

KnarfB

[Tesla DeLorean]

void printsize(uint32_t size, char *s)
{
  if (size >= 1000000) // Storage vendor math
    printf(" %6.1lf GB %s\n", (double)size / 1000000.0, s);
  else if (size >= 1000)
    printf(" %6.1lf MB %s\n", (double)size / 1000.0, s);
  else
   printf(" %6.1lf KB %s\n", (double)size, s);
}
 
 
{
  FATFS *fs;
  DWORD fre_clust, fre_sect, tot_sect;
 
  /* Get volume information and free clusters of drive 1 */
 
  res = f_getfree("", &fre_clust, &fs);
 
  if (res != FR_OK)
  {
#ifdef DBG
    printf("res = %d f_getfree\n", res);
#endif
    return;
  }
 
  switch(fs->fs_type)
  {
    case FS_FAT12 : puts("FAT12"); break;
    case FS_FAT16 : puts("FAT16"); break;
    case FS_FAT32 : puts("FAT32"); break;
    case FS_EXFAT : puts("EXFAT"); break;
    default : puts("Unknown FAT");
  }
 
  /* Get total sectors and free sectors */
  tot_sect = (fs->n_fatent - 2) * fs->csize;
  fre_sect = fre_clust * fs->csize;
 
  /* Print the free space (assuming 512 bytes/sector) */
  printsize(tot_sect / 2, "total drive space");
  printsize(fre_sect / 2, "available");
  printsize((tot_sect - fre_sect) / 2, "used");
}