There are many options to configure the functions of FatFs for each project. The configuration options are defined in the ffconf.h.
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.
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. |
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. |
Disable(0) or Enable(1). This option switches filtered directory read feature and related functions, f_findfirst and f_findnext.
Disable(0) or Enable(1). This option switches f_mkfs function.
Disable(0) or Enable(1). This option switches fast seek feature to enable accelerated mode of f_lseek, f_read and f_write function. For more information, read here.
Disable(0) or Enable(1). This option switches volume label functions, f_getlabel and f_setlabel.
Disable(0) or Enable(1). This option switches f_forward function. also _FS_TINY needs to be set to 1.
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) |
This option switches the LFN feature. When enable the LFN feature, Unicode handling functions option/unicode.c must be added to the project. The LFN working buffer occupies (_MAX_LFN + 1) * 2 bytes. 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, must be added to the project.
| Value | Description |
|---|---|
| 0 | Disable LFN feature. 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. |
This option defines the size of LFN working buffer from 12 to 255 in unit of character. This option has no effect when LFN feature is disabled.
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 feature and set this option to 1. This option also affects behavior of string I/O functions. When LFN feature is disabled, this option must be 0. For more information, read here.
When Unicode API is selected by _LFN_UNICODE, 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 |
This option configures relative path feature. Note that directory items read via directory functions are affected by this option. For more information, read here.
| Value | Description |
|---|---|
| 0 | Disable relative path feature and remove related functions. |
| 1 | Enable relative path feature. f_chdir and f_chdrive function is available. |
| 2 | f_getcwd function is available in addition to 1 |
This option configures number of volumes (logical drives, from 1 to 9) to be used.
Disable(0) or Enable(1). This option switches string volume ID feature. When enabled, also pre-defined strings in _VOLUME_STRS can be used as drive identifier in the path name.
This option defines the drive ID strings for each logical drives. Number of items must be equal to _VOLUMES. Valid characters for the drive ID strings are: A-Z and 0-9.
Disable(0) or Enable(1). This option switches multi-partition feature. By default (0), each logical drive number is bound to the same physical drive number and only an FAT volume each physical drive are 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 enabled. For more information, read here.
This set of options defines size of sector on the low level disk I/O interface, disk_read and disk_write function. Valid numbers are 512, 1024, 2048 and 4096. _MIN_SS defines minimum size of sector and _MAX_SS defines the maximum size of sector. Always set both 512 for all type of memory cards 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.
Disable(0) or Enable(1). This option switches ATA-TRIM feature. To enable Trim feature, also CTRL_TRIM command should be implemented to the disk_ioctl function.
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. |
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.
Use RTC(0) or Do not use RTC(1). This option controls timestamp feature. If the system does not have an RTC function or valid timestamp is not needed, set _FS_NORTC to 1 to disable the timestamp feature. Any object modified by FatFs will have a fixed timestamp value defined by _NORTC_MON, _NORTC_MDAY and _NORTC_YEAR. To use the timestamp feature, set _FS_NORTC to 0 and add get_fattime function to the project to get the current time form RTC. This option has no effect at read-only configuration.
This set of options defines default timestamp to be used at no RTC systems. This option has no effect at read-only configuration or _FS_NORTC == 0.
This option switches file lock feature to control duplicated file open and illegal operations to open objects. Note that the file lock feature is independent of re-entrancy. This option must be 0 at read-only configuration.
| Value | Description |
|---|---|
| 0 | Disable file lock feature. To avoid volume corruption, application program should avoid illegal open, remove and rename to the open objects. |
| >0 | Enable file lock feature. 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. |
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 feature. To enable this feature, also user provided synchronization handlers, ff_req_grant, ff_rel_grant, ff_del_syncobj and ff_cre_syncobj, must be added to the project. Samples are available in option/syscall.c.
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.
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.
This is an only platform dependent option. It defines which access method is used to the word data on the FAT volume.
| Value | Description |
|---|---|
| 0 | Byte-by-byte access. Always compatible with all platforms. |
| 1 | Word access. Code size will be slightly reduced but do not choose this unless under both the following conditions. * Unaligned memory access is always allowed to ALL instructions. * Byte order on the memory is little-endian. |
Following table shows an example of allowable settings of some type of processors.
ARM7TDMI 0 *2 ColdFire 0 *1 V850E 0 *2 Cortex-M3 0 *3 Z80 0/1 V850ES 0/1 Cortex-M0 0 *2 x86 0/1 TLCS-870 0/1 AVR 0/1 RX600(LE) 0/1 TLCS-900 0/1 AVR32 0 *1 RL78 0 *2 R32C 0 *2 PIC18 0/1 SH-2 0 *1 M16C 0/1 PIC24 0 *2 H8S 0 *1 MSP430 0 *2 PIC32 0 *1 H8/300H 0 *1 8051 0/1 *1:Big-endian. *2:Unaligned memory access is not supported. *3:Some compilers generate LDM/STM for mem_cpy function.