FatFs - Configuration Options

# Configuration Options

There are many options to configure the functions of FatFs for each project. The configuration options are defined in the `ffconf.h`.

### Function Configurations

#### _FS_READONLY

Read/Write (0) or Read-only (1). Read-only configuration removes writing API functions, `f_write`, `f_sync`, `f_unlink`, `f_mkdir`, `f_chmod`, `f_rename`, `f_truncate`, `f_getfree` and optional writing functions as well.

#### _FS_MINIMIZE

This option defines minimization level to remove some basic API functions as follows:

Value | Description
--- | ---
0 | All basic API functions are available.
1 | `f_stat`, `f_getfree`, `f_unlink`, `f_mkdir`, `f_chmod`, `f_utime`, `f_truncate` and `f_rename` function are removed.
2 | `f_opendir`, `f_readdir` and `f_closedir` function are removed in addition to 1.
3 | `f_lseek` function is removed in addition to 2.

#### _USE_STRFUNC

This option switches string functions, `f_gets`, `f_putc`, `f_puts` and `f_printf`.

Value | Description
--- | ---
0 | Disable string functions.
1 | Enable string functions without LF-CRLF conversion.
2 | Enable string functions with LF-CRLF conversion.

#### _USE_FIND

Disable (0) or Enable (1) filtered directory read functions, `f_findfirst` and `f_findnext`. Also `_FS_MINIMIZE` needs to be 0 or 1.

#### _USE_MKFS

Disable (0) or Enable (1) `f_mkfs` function.

#### _USE_FASTSEEK

Disable (0) or Enable (1) fast seek function to enable accelerated mode of `f_lseek`, `f_read` and `f_write` function. For more information, read here.

#### _USE_EXPAND

Disable (0) or Enable (1) , `f_enpand` function. Also `_FS_READONLY` needs to be 0.

#### _USE_CHMOD

Disable (0) or Enable (1) metadata manipulation functions, `f_chmod` and `f_utime`. Also `_FS_READONLY` needs to be 0.

#### _USE_LABEL

Disable (0) or Enable (1) volume label functions, `f_getlabel` and `f_setlabel`.

#### _USE_FORWARD

Disable (0) or Enable (1) `f_forward` function.

### Namespace and Locale Configurations

#### _CODE_PAGE

This option specifies the OEM code page to be used on the target system. Incorrect setting of the code page can cause a file open failure. If any extended character is not used at all, there is no difference between any code pages.

Value | Description
--- | ---
1 | ASCII (valid at non-LFN cfg.)
437 | U.S.
720 | Arabic
737 | Greek
771 | KBL
775 | Baltic
850 | Latin 1
852 | Latin 2
855 | Cyrillic
857 | Turkish
860 | Portuguese
861 | Icelandic
862 | Hebrew
863 | Canadian French
864 | Arabic
865 | Nordic
866 | Russian
869 | Greek 2
932 | Japanese (DBCS)
936 | Simplified Chinese (DBCS)
949 | Korean (DBCS)
950 | Traditional Chinese (DBCS)

#### _USE_LFN

This option switches the support for long file name (LFN). When enable the LFN, Unicode support functions `option/unicode.c` need to be added to the project. The working buffer occupies `(_MAX_LFN + 1) * 2` bytes and additional 608 bytes when exFAT enabled. When use stack for the working buffer, take care on stack overflow. When use heap memory for the working buffer, memory management functions, `ff_memalloc` and `ff_memfree`, need to be added to the project.

Value | Description
--- | ---
0 | Disable LFN. Only 8.3 format can be used.
1 | Enable LFN with static working buffer on the BSS. Always NOT thread-safe.
2 | Enable LFN with dynamic working buffer on the STACK.
3 | Enable LFN with dynamic working buffer on the HEAP.

#### _MAX_LFN

This option defines the size of LFN working buffer from 12 to 255 in unit of character. This option has no effect when LFN is disabled.

#### _LFN_UNICODE

ANSI/OEM (0) or Unicode (1). This option switches character encoding on the API. To use Unicode (UTF16) string for the path name, enable LFN and set this option to 1. This option also affects behavior of string I/O functions. When LFN is disabled, this option must be 0. For more information, read here.

#### _STRF_ENCODE

When Unicode API is selected by setting `_LFN_UNICODE` 1, this option defines the assumption of character encoding on the file to be read/written via string I/O functions, `f_gets`, `f_putc`, `f_puts` and `f_printf`. This option has no effect when `_LFN_UNICODE = 0`.

Value | Description
--- | ---
0 | ANSI/OEM
1 | UTF-16LE
2 | UTF-16BE
3 | UTF-8

#### _FS_RPATH

This option configures relative path function. For more information, read here.

Value | Description
--- | ---
0 | Disable relative path function and remove related functions.
1 | Enable relative path function. `f_chdir` and `f_chdrive` function is available.
2 | `f_getcwd` function is available in addition to 1

### Volume/Drive Configurations

#### _VOLUMES

This option configures number of volumes (logical drives, from 1 to 10) to be used.

#### _STR_VOLUME_ID

Disable (0) or Enable (1). This option switches the support for string volume ID. When enabled, also pre-defined strings in `_VOLUME_STRS` can be used as drive identifier in the path name.

#### _VOLUME_STRS

This option defines the drive ID strings for each logical drives. Number of items must not be less than `_VOLUMES`. Valid characters for the drive ID string are: A-Z and 0-9.

#### _MULTI_PARTITION

Disable (0) or Enable (1). This option switches multi-partition function. By default (0), each logical drive number is bound to the same physical drive number and only an FAT volume in the physical drive is mounted. When enabled, each logical drive is bound to the partition on the physical drive listed in the user defined partition resolution table `VolToPart[]`. Also `f_fdisk` funciton will be available. For more information, read here.

#### _MIN_SS, _MAX_SS

This set of options defines the size of sector on low level disk I/O interface, `disk_read` and `disk_write` function. Valid values are 512, 1024, 2048 and 4096. `_MIN_SS` defines minimum sector size and `_MAX_SS` defines the maximum sector size. Always set both 512 for any type of memory card and harddisk. But a larger value may be required for on-board flash memory and some type of optical media. When `_MAX_SS > _MIN_SS`, FatFs is configured to variable sector size and `GET_SECTOR_SIZE` command must be implemented to the `disk_ioctl` function.

#### _USE_TRIM

Disable (0) or Enable (1). This option switches ATA-TRIM function. To enable Trim function, also `CTRL_TRIM` command should be implemented to the `disk_ioctl` function.

#### _FS_NOFSINFO

0 to 3. If you need to know correct free space on the FAT32 volume, set bit 0 of this option, and `f_getfree` function at first time after volume mount will force a full FAT scan. Bit 1 controls the use of last allocated cluster number.

Value | Description
--- | ---
bit0=0 | Use free cluster count in the FSINFO if available.
bit0=1 | Do not trust free cluster count in the FSINFO.
bit1=0 | Use last allocated cluster number in the FSINFO to find a free cluster if available.
bit1=1 | Do not trust last allocated cluster number in the FSINFO.

### System Configurations

#### _FS_TINY

Normal (0) or Tiny (1). At the tiny configuration, size of the file object `FIL` is reduced `_MAX_SS` bytes. Instead of private data buffer eliminated from the file object, common sector buffer in the file system object `FATFS` is used for the file data transfer.

#### _FS_EXFAT

This option switches support for the exFAT file system in addition to the FAT file system, Enabled(1) or Disabled(1). To enable this feature, also LFN must be enabled and configureing `_LFN_UNICODE = 1` and `_MAX_LFN = 255` is recommended for full-featured exFAT function. Note that enabling exFAT discards C89 compatibility because of need for 64-bit integer type.

#### _FS_NORTC

Use RTC (0) or Do not use RTC (1). This option controls timestamp function. If the system does not have an RTC function or valid timestamp is not needed, set `_FS_NORTC` to 1 to disable the timestamp function. Any object modified by FatFs will have a fixed timestamp value defined by `_NORTC_MON`, `_NORTC_MDAY` and `_NORTC_YEAR`. To use the timestamp function, set `_FS_NORTC = 0` and add `get_fattime` function to the project to get the current time form real-time clock. This option has no effect at read-only configuration.

#### _NORTC_MON, _NORTC_MDAY, _NORTC_YEAR

This set of options defines the time to be used at no RTC systems. This option has no effect at read-only configuration or `_FS_NORTC = 0`.

#### _FS_LOCK

This option switches file lock function to control duplicated file open and illegal operations to open objects. Note that the file lock function is independent of re-entrancy. This option must be 0 at read-only configuration.

Value | Description
--- | ---
0 | Disable file lock function. To avoid volume corruption, application program should avoid illegal open, remove and rename to the open objects.
>0 | Enable file lock function. The value defines how many files/sub-directories can be opened simultaneously under file lock control. Illigal operations to the open object will be rejected with `FR_LOCKED`.

#### _FS_REENTRANT

Disable (0) or Enable (1). This option switches the re-entrancy (thread safe) of the FatFs module itself. Note that file/directory access to the different volume is always re-entrant and it can work simultaneously regardless of this option but volume control functions, `f_mount`, `f_mkfs` and `f_fdisk`, are always not re-entrant. Only file/directory access to the same volume, in other words, exclusive use of each file system object, is under control of this function. To enable this feature, also user provided synchronization handlers, `ff_req_grant`, `ff_rel_grant`, `ff_del_syncobj` and `ff_cre_syncobj`, need to be added to the project. Sample code is available in `option/syscall.c`.

#### _FS_TIMEOUT

Number of time ticks to abort the file function with `FR_TIMEOUT` when wait time is too long. This option has no effect when `_FS_REENTRANT = 0`.

#### _SYNC_t

This option defines O/S dependent sync object type. e.g. `HANDLE`, `ID`, `OS_EVENT*`, `SemaphoreHandle_t` and etc. A header file for O/S definitions needs to be included somewhere in the scope of `ff.c`. This option has no effect when `_FS_REENTRANT = 0`.

Return