The f_close function closes an open file.
FRESULT f_close ( FIL* fp /* [IN] Pointer to the file object */ );
FR_OK, FR_DISK_ERR, FR_INT_ERR, FR_INVALID_OBJECT, FR_TIMEOUT
The f_close function closes an open file object. If any data has been written to the file, the cached information of the file is written back to the volume. After the function succeeded, the file object is no longer valid and it can be discarded.
Note that if the file object is in read-only mode and _FS_LOCK option is not enabled, the file object can also be discarded without this process. However this is not recommended for future compatibility.
Always available.