FAT Filesystem Support
ESP-IDF uses the FatFs library to work with FAT filesystems. FatFs resides in the fatfs
component. Although the library can be used directly, many of its features can be accessed via VFS using the C standard library and POSIX API functions.
Additionally, FatFs has been modified to support the runtime pluggable disk I/O layer. This allows mapping of FatFs drives to physical disks at runtime.
Using FatFs with VFS
The header file fatfs/vfs/esp_vfs_fat.h defines the functions for connecting FatFs and VFS.
The function esp_vfs_fat_register()
allocates a FATFS
structure and registers a given path prefix in VFS. Subsequent operations on files starting with this prefix are forwarded to FatFs APIs.
The function esp_vfs_fat_unregister_path()
deletes the registration with VFS, and frees the FATFS
structure.
Most applications use the following workflow when working with esp_vfs_fat_
functions:
- Call
esp_vfs_fat_register()
to specify: Path prefix where to mount the filesystem (e.g.,
"/sdcard"
,"/spiflash"
)FatFs drive number
A variable which receives the pointer to the
FATFS
structure
- Call
Call
ff_diskio_register()
to register the disk I/O driver for the drive number used in Step 1.To mount the filesystem using the same drive number which was passed to
esp_vfs_fat_register()
, call the FatFs functionf_mount()
. If the filesystem is not present on the target logical drive,f_mount()
will fail with theFR_NO_FILESYSTEM
error. In such case, callf_mkfs()
to create a fresh FatFS structure on the drive first, and then callf_mount()
again. Note that SD cards need to be partitioned withf_fdisk()
prior to previously described steps. For more information, see FatFs documentation.Call the C standard library and POSIX API functions to perform such actions on files as open, read, write, erase, copy, etc. Use paths starting with the path prefix passed to
esp_vfs_register()
(for example,"/sdcard/hello.txt"
). The filesystem uses 8.3 filenames format (SFN) by default. If you need to use long filenames (LFN), enable the CONFIG_FATFS_LONG_FILENAMES option. Please refer to FatFs filenames for more details.Optionally, call the FatFs library functions directly. In this case, use paths without a VFS prefix, for example,
"/hello.txt"
.Close all open files.
Call the FatFs function
f_mount()
for the same drive number with NULLFATFS*
argument to unmount the filesystem.Call the FatFs function
ff_diskio_register()
with NULLff_diskio_impl_t*
argument and the same drive number to unregister the disk I/O driver.Call
esp_vfs_fat_unregister_path()
with the path where the file system is mounted to remove FatFs from VFS, and free theFATFS
structure allocated in Step 1.
The convenience functions esp_vfs_fat_sdmmc_mount()
, esp_vfs_fat_sdspi_mount()
, and esp_vfs_fat_sdcard_unmount()
wrap the steps described above and also handle SD card initialization. These functions are described in the next section.
Note
Because FAT filesystem does not support hardlinks, link()
copies contents of the file instead. (This only applies to files on FatFs volumes.)
Using FatFs with VFS and SD Cards
The header file fatfs/vfs/esp_vfs_fat.h defines convenience functions esp_vfs_fat_sdmmc_mount()
, esp_vfs_fat_sdspi_mount()
, and esp_vfs_fat_sdcard_unmount()
. These functions perform Steps 1–3 and 7–9 respectively and handle SD card initialization, but provide only limited error handling. Developers are encouraged to check its source code and incorporate more advanced features into production applications.
The convenience function esp_vfs_fat_sdmmc_unmount()
unmounts the filesystem and releases the resources acquired by esp_vfs_fat_sdmmc_mount()
.
Using FatFs with VFS in Read-Only Mode
The header file fatfs/vfs/esp_vfs_fat.h also defines the convenience functions esp_vfs_fat_spiflash_mount_ro()
and esp_vfs_fat_spiflash_unmount_ro()
. These functions perform Steps 1-3 and 7-9 respectively for read-only FAT partitions. These are particularly helpful for data partitions written only once during factory provisioning, which will not be changed by production application throughout the lifetime of the hardware.
Configuration options
The following configuration options are available for the FatFs component:
CONFIG_FATFS_USE_FASTSEEK - If enabled, the POSIX
lseek()
function will be performed faster. The fast seek does not work for files in write mode, so to take advantage of fast seek, you should open (or close and then reopen) the file in read-only mode.CONFIG_FATFS_IMMEDIATE_FSYNC - If enabled, the FatFs will automatically call
f_sync()
to flush recent file changes after each call ofwrite()
,pwrite()
,link()
,truncate()
andftruncate()
functions. This feature improves file-consistency and size reporting accuracy for the FatFs, at a price on decreased performance due to frequent disk operations.CONFIG_FATFS_LINK_LOCK - If enabled, this option guarantees the API thread safety, while disabling this option might be necessary for applications that require fast frequent small file operations (e.g., logging to a file). Note that if this option is disabled, the copying performed by
link()
will be non-atomic. In such case, usinglink()
on a large file on the same volume in a different task is not guaranteed to be thread safe.
FatFS Disk IO Layer
FatFs has been extended with API functions that register the disk I/O driver at runtime.
These APIs provide implementation of disk I/O functions for SD/MMC cards and can be registered for the given FatFs drive number using the function ff_diskio_register_sdmmc()
.
-
void ff_diskio_register(BYTE pdrv, const ff_diskio_impl_t *discio_impl)
Register or unregister diskio driver for given drive number.
When FATFS library calls one of disk_xxx functions for driver number pdrv, corresponding function in discio_impl for given pdrv will be called.
- Parameters
pdrv -- drive number
discio_impl -- pointer to ff_diskio_impl_t structure with diskio functions or NULL to unregister and free previously registered drive
-
struct ff_diskio_impl_t
Structure of pointers to disk IO driver functions.
See FatFs documentation for details about these functions
Public Members
-
DSTATUS (*init)(unsigned char pdrv)
disk initialization function
-
DSTATUS (*status)(unsigned char pdrv)
disk status check function
-
DRESULT (*read)(unsigned char pdrv, unsigned char *buff, uint32_t sector, unsigned count)
sector read function
-
DRESULT (*write)(unsigned char pdrv, const unsigned char *buff, uint32_t sector, unsigned count)
sector write function
-
DRESULT (*ioctl)(unsigned char pdrv, unsigned char cmd, void *buff)
function to get info about disk and do some misc operations
-
DSTATUS (*init)(unsigned char pdrv)
-
void ff_diskio_register_sdmmc(unsigned char pdrv, sdmmc_card_t *card)
Register SD/MMC diskio driver
- Parameters
pdrv -- drive number
card -- pointer to sdmmc_card_t structure describing a card; card should be initialized before calling f_mount.
-
esp_err_t ff_diskio_register_wl_partition(unsigned char pdrv, wl_handle_t flash_handle)
Register spi flash partition
- Parameters
pdrv -- drive number
flash_handle -- handle of the wear levelling partition.
-
esp_err_t ff_diskio_register_raw_partition(unsigned char pdrv, const esp_partition_t *part_handle)
Register spi flash partition
- Parameters
pdrv -- drive number
part_handle -- pointer to raw flash partition.
FatFs Partition Generator
We provide a partition generator for FatFs (wl_fatfsgen.py ) which is integrated into the build system and could be easily used in the user project.
The tool is used to create filesystem images on a host and populate it with content of the specified host folder.
The script is based on the partition generator (fatfsgen.py ). Apart from generating partition, it can also initialize wear levelling.
The latest version supports both short and long file names, FAT12 and FAT16. The long file names are limited to 255 characters and can contain multiple periods (.
) characters within the filename and additional characters +
, ,
, ;
, =
, [
and ]
.
An in-depth description of the FatFs partition generator and analyzer can be found at Generating and parsing FAT partition on host.
Build System Integration with FatFs Partition Generator
It is possible to invoke FatFs generator directly from the CMake build system by calling fatfs_create_spiflash_image
:
fatfs_create_spiflash_image(<partition> <base_dir> [FLASH_IN_PROJECT])
If you prefer generating partition without wear levelling support, you can use fatfs_create_rawflash_image
:
fatfs_create_rawflash_image(<partition> <base_dir> [FLASH_IN_PROJECT])
fatfs_create_spiflash_image
respectively fatfs_create_rawflash_image
must be called from project's CMakeLists.txt.
If you decide for any reason to use fatfs_create_rawflash_image
(without wear levelling support), beware that it supports mounting only in read-only mode in the device.
The arguments of the function are as follows:
partition - the name of the partition as defined in the partition table (e.g., storage/fatfs/fatfsgen/partitions_example.csv).
base_dir - the directory that will be encoded to FatFs partition and optionally flashed into the device. Beware that you have to specify the suitable size of the partition in the partition table.
flag
FLASH_IN_PROJECT
- optionally, users can have the image automatically flashed together with the app binaries, partition tables, etc. onidf.py flash -p <PORT>
by specifyingFLASH_IN_PROJECT
.flag
PRESERVE_TIME
- optionally, users can force preserving the timestamps from the source folder to the target image. Without preserving the time, every timestamp will be set to the FATFS default initial time (1st January 1980).flag
ONE_FAT
- optionally, users can still choose to generate a FATFS volume with a single FAT (file allocation table) instead of two. This makes the free space in the FATFS volume a bit larger (bynumber of sectors used by FAT * sector size
) but also more prone to corruption.
For example:
fatfs_create_spiflash_image(my_fatfs_partition my_folder FLASH_IN_PROJECT)
If FLASH_IN_PROJECT is not specified, the image will still be generated, but you will have to flash it manually using esptool.py
or a custom build system target.
For an example, see storage/fatfs/fatfsgen.
FatFs Partition Analyzer
(fatfsparse.py ) is a partition analyzing tool for FatFs.
It is a reverse tool of (fatfsgen.py ), i.e., it can generate the folder structure on the host based on the FatFs image.
Usage:
./fatfsparse.py [-h] [--wl-layer {detect,enabled,disabled}] [--verbose] fatfs_image.img
Parameter --verbose prints detailed information from boot sector of the FatFs image to the terminal before folder structure is generated.
FATFS Minimum Partition Size and Limits
The FATFS component supports FAT12, FAT16, and FAT32 file system types. The file system type is determined by the number of clusters (calculated as data sectors divided by sectors per cluster) on the volume. The minimum partition size is defined by the number of sectors allocated to FAT tables, root directories and data clusters.
The minimum supported size for a FAT partition with wear leveling enabled is 32 KB for a sector size of 4096 bytes. For a sector size of 512 bytes, the minimum partition size varies based on the WL configuration: 20 KB for Performance mode and 28 KB for Safety mode (requiring 2 extra sectors).
For a partition with wear leveling enabled, 4 sectors will be reserved for wear-leveling operations, and 4 sectors will be used by the FATFS (1 reserved sector, 1 FAT sector, 1 root directory sector and 1 data sector).
Increasing the partition size will allocate additional data sectors, allowing for more storage space.
For partition sizes less than 528 KB, 1 root directory sector will be allocated; for larger partitions, 4 root directory sectors will be used.
By default, two FAT sectors are created, increasing the partition size by one sector to accommodate the extra FAT sector. To enable a single FAT sector, configure the use_one_fat option in struct esp_vfs_fat_mount_config_t (see fatfs/vfs/esp_vfs_fat.h). Enabling this option allows the minimum partition size to be reduced to 32 KB.
The general formula for calculating the partition size for a wear-leveled partition is:
partition_size = Wear-levelling sectors * FLASH_SEC_SIZE + FATFS partition sectors * FAT_SEC_SIZE
Where:
Wear-leveling sectors are fixed at 4
FLASH_SEC_SIZE is 4096 bytes
FATFS partition sectors include: 1 reserved sector + FAT sectors + root directory sectors + data sectors
FAT_SEC_SIZE can be either 512 bytes or 4096 bytes, depending on the configuration
For read-only partitions without wear leveling enabled and a sector size of 512 bytes, the minimum partition size can be reduced to as low as 2 KB.
Please refer File System Considerations for further details.
Application Examples
storage/fatfs/getting_started demonstrates the minimal setup required to store persistent data on SPI flash using the FatFS, including mounting the file system, opening a file, performing basic read and write operations, and unmounting the file system.
storage/fatfs/fs_operations demonstrates more advanced FatFS operations, including reading and writing files, creating, moving, and deleting files and directories, and inspecting file details.
storage/fatfs/ext_flash demonstrates how to operate an external SPI flash formatted with FatFS, including initializing the SPI bus, configuring the flash chip, registering it as a partition, and performing read and write operations.
High-level API Reference
Header File
This header file can be included with:
#include "esp_vfs_fat.h"
This header file is a part of the API provided by the
fatfs
component. To declare that your component depends onfatfs
, add the following to your CMakeLists.txt:REQUIRES fatfs
or
PRIV_REQUIRES fatfs
Functions
-
esp_err_t esp_vfs_fat_register_cfg(const esp_vfs_fat_conf_t *conf, FATFS **out_fs)
Register FATFS with VFS component.
This function registers given FAT drive in VFS, at the specified base path. Input arguments are held in esp_vfs_fat_conf_t structure. If only one drive is used, fat_drive argument can be an empty string. Refer to FATFS library documentation on how to specify FAT drive. This function also allocates FATFS structure which should be used for f_mount call.
Note
This function doesn't mount the drive into FATFS, it just connects POSIX and C standard library IO function with FATFS. You need to mount desired drive into FATFS separately.
- Parameters
conf -- pointer to esp_vfs_fat_conf_t configuration structure
out_fs -- [out] pointer to FATFS structure which can be used for FATFS f_mount call is returned via this argument.
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_register was already called
ESP_ERR_NO_MEM if not enough memory or too many VFSes already registered
-
esp_err_t esp_vfs_fat_unregister_path(const char *base_path)
Un-register FATFS from VFS.
Note
FATFS structure returned by esp_vfs_fat_register is destroyed after this call. Make sure to call f_mount function to unmount it before calling esp_vfs_fat_unregister_ctx. Difference between this function and the one above is that this one will release the correct drive, while the one above will release the last registered one
- Parameters
base_path -- path prefix where FATFS is registered. This is the same used when esp_vfs_fat_register was called
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if FATFS is not registered in VFS
-
esp_err_t esp_vfs_fat_sdmmc_mount(const char *base_path, const sdmmc_host_t *host_config, const void *slot_config, const esp_vfs_fat_mount_config_t *mount_config, sdmmc_card_t **out_card)
Convenience function to get FAT filesystem on SD card registered in VFS.
This is an all-in-one function which does the following:
initializes SDMMC driver or SPI driver with configuration in host_config
initializes SD card with configuration in slot_config
mounts FAT partition on SD card using FATFS library, with configuration in mount_config
registers FATFS library with VFS, with prefix given by base_prefix variable
This function is intended to make example code more compact. For real world applications, developers should implement the logic of probing SD card, locating and mounting partition, and registering FATFS in VFS, with proper error checking and handling of exceptional conditions.
Note
Use this API to mount a card through SDSPI is deprecated. Please call
esp_vfs_fat_sdspi_mount()
instead for that case.- Parameters
base_path -- path where partition should be registered (e.g. "/sdcard")
host_config -- Pointer to structure describing SDMMC host. When using SDMMC peripheral, this structure can be initialized using SDMMC_HOST_DEFAULT() macro. When using SPI peripheral, this structure can be initialized using SDSPI_HOST_DEFAULT() macro.
slot_config -- Pointer to structure with slot configuration. For SDMMC peripheral, pass a pointer to sdmmc_slot_config_t structure initialized using SDMMC_SLOT_CONFIG_DEFAULT.
mount_config -- pointer to structure with extra parameters for mounting FATFS
out_card -- [out] if not NULL, pointer to the card information structure will be returned via this argument
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount was already called
ESP_ERR_NO_MEM if memory can not be allocated
ESP_FAIL if partition can not be mounted
other error codes from SDMMC or SPI drivers, SDMMC protocol, or FATFS drivers
-
esp_err_t esp_vfs_fat_sdspi_mount(const char *base_path, const sdmmc_host_t *host_config_input, const sdspi_device_config_t *slot_config, const esp_vfs_fat_mount_config_t *mount_config, sdmmc_card_t **out_card)
Convenience function to get FAT filesystem on SD card registered in VFS.
This is an all-in-one function which does the following:
initializes an SPI Master device based on the SPI Master driver with configuration in slot_config, and attach it to an initialized SPI bus.
initializes SD card with configuration in host_config_input
mounts FAT partition on SD card using FATFS library, with configuration in mount_config
registers FATFS library with VFS, with prefix given by base_prefix variable
This function is intended to make example code more compact. For real world applications, developers should implement the logic of probing SD card, locating and mounting partition, and registering FATFS in VFS, with proper error checking and handling of exceptional conditions.
Note
This function try to attach the new SD SPI device to the bus specified in host_config. Make sure the SPI bus specified in
host_config->slot
have been initialized byspi_bus_initialize()
before.- Parameters
base_path -- path where partition should be registered (e.g. "/sdcard")
host_config_input -- Pointer to structure describing SDMMC host. This structure can be initialized using SDSPI_HOST_DEFAULT() macro.
slot_config -- Pointer to structure with slot configuration. For SPI peripheral, pass a pointer to sdspi_device_config_t structure initialized using SDSPI_DEVICE_CONFIG_DEFAULT().
mount_config -- pointer to structure with extra parameters for mounting FATFS
out_card -- [out] If not NULL, pointer to the card information structure will be returned via this argument. It is suggested to hold this handle and use it to unmount the card later if needed. Otherwise it's not suggested to use more than one card at the same time and unmount one of them in your application.
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount was already called
ESP_ERR_NO_MEM if memory can not be allocated
ESP_FAIL if partition can not be mounted
other error codes from SDMMC or SPI drivers, SDMMC protocol, or FATFS drivers
-
esp_err_t esp_vfs_fat_sdmmc_unmount(void)
Unmount FAT filesystem and release resources acquired using esp_vfs_fat_sdmmc_mount.
- Deprecated:
Use
esp_vfs_fat_sdcard_unmount()
instead.
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount hasn't been called
-
esp_err_t esp_vfs_fat_sdcard_unmount(const char *base_path, sdmmc_card_t *card)
Unmount an SD card from the FAT filesystem and release resources acquired using
esp_vfs_fat_sdmmc_mount()
oresp_vfs_fat_sdspi_mount()
- Returns
ESP_OK on success
ESP_ERR_INVALID_ARG if the card argument is unregistered
ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount hasn't been called
-
esp_err_t esp_vfs_fat_sdcard_format_cfg(const char *base_path, sdmmc_card_t *card, esp_vfs_fat_mount_config_t *cfg)
Format FAT filesystem with given configuration.
Note
This API should be only called when the FAT is already mounted.
- Parameters
base_path -- Path where partition should be registered (e.g. "/sdcard")
card -- Pointer to the card handle, which should be initialised by calling
esp_vfs_fat_sdspi_mount
firstcfg -- Pointer to structure with extra parameters for formatting FATFS (only relevant fields are used). If NULL, the previous configuration will be used.
- Returns
ESP_OK
ESP_ERR_INVALID_STATE: FAT partition isn't mounted, call esp_vfs_fat_sdmmc_mount or esp_vfs_fat_sdspi_mount first
ESP_ERR_NO_MEM: if memory can not be allocated
ESP_FAIL: fail to format it, or fail to mount back
-
esp_err_t esp_vfs_fat_sdcard_format(const char *base_path, sdmmc_card_t *card)
Format FAT filesystem.
Note
This API should be only called when the FAT is already mounted.
- Parameters
base_path -- Path where partition should be registered (e.g. "/sdcard")
card -- Pointer to the card handle, which should be initialised by calling
esp_vfs_fat_sdspi_mount
first
- Returns
ESP_OK
ESP_ERR_INVALID_STATE: FAT partition isn't mounted, call esp_vfs_fat_sdmmc_mount or esp_vfs_fat_sdspi_mount first
ESP_ERR_NO_MEM: if memory can not be allocated
ESP_FAIL: fail to format it, or fail to mount back
-
esp_err_t esp_vfs_fat_spiflash_mount_rw_wl(const char *base_path, const char *partition_label, const esp_vfs_fat_mount_config_t *mount_config, wl_handle_t *wl_handle)
Convenience function to initialize FAT filesystem in SPI flash and register it in VFS.
This is an all-in-one function which does the following:
finds the partition with defined partition_label. Partition label should be configured in the partition table.
initializes flash wear levelling library on top of the given partition
mounts FAT partition using FATFS library on top of flash wear levelling library
registers FATFS library with VFS, with prefix given by base_prefix variable
This function is intended to make example code more compact.
- Parameters
base_path -- path where FATFS partition should be mounted (e.g. "/spiflash")
partition_label -- label of the partition which should be used
mount_config -- pointer to structure with extra parameters for mounting FATFS
wl_handle -- [out] wear levelling driver handle
- Returns
ESP_OK on success
ESP_ERR_NOT_FOUND if the partition table does not contain FATFS partition with given label
ESP_ERR_INVALID_STATE if esp_vfs_fat_spiflash_mount_rw_wl was already called
ESP_ERR_NO_MEM if memory can not be allocated
ESP_FAIL if partition can not be mounted
other error codes from wear levelling library, SPI flash driver, or FATFS drivers
-
esp_err_t esp_vfs_fat_spiflash_unmount_rw_wl(const char *base_path, wl_handle_t wl_handle)
Unmount FAT filesystem and release resources acquired using esp_vfs_fat_spiflash_mount_rw_wl.
- Parameters
base_path -- path where partition should be registered (e.g. "/spiflash")
wl_handle -- wear levelling driver handle returned by esp_vfs_fat_spiflash_mount_rw_wl
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_spiflash_mount_rw_wl hasn't been called
-
esp_err_t esp_vfs_fat_spiflash_format_cfg_rw_wl(const char *base_path, const char *partition_label, esp_vfs_fat_mount_config_t *cfg)
Format FAT filesystem with given configuration.
Note
This API can be called when the FAT is mounted / not mounted. If this API is called when the FAT isn't mounted (by calling esp_vfs_fat_spiflash_mount_rw_wl), this API will first mount the FAT then format it, then restore back to the original state.
- Parameters
base_path -- Path where partition should be registered (e.g. "/spiflash")
partition_label -- Label of the partition which should be used
cfg -- Pointer to structure with extra parameters for formatting FATFS (only relevant fields are used). If NULL and mounted the previous configuration will be used. If NULL and unmounted the default configuration will be used.
- Returns
ESP_OK
ESP_ERR_NO_MEM: if memory can not be allocated
Other errors from esp_vfs_fat_spiflash_mount_rw_wl
-
esp_err_t esp_vfs_fat_spiflash_format_rw_wl(const char *base_path, const char *partition_label)
Format FAT filesystem.
Note
This API can be called when the FAT is mounted / not mounted. If this API is called when the FAT isn't mounted (by calling esp_vfs_fat_spiflash_mount_rw_wl), this API will first mount the FAT then format it, then restore back to the original state.
- Parameters
base_path -- Path where partition should be registered (e.g. "/spiflash")
partition_label -- Label of the partition which should be used
- Returns
ESP_OK
ESP_ERR_NO_MEM: if memory can not be allocated
Other errors from esp_vfs_fat_spiflash_mount_rw_wl
-
esp_err_t esp_vfs_fat_spiflash_mount_ro(const char *base_path, const char *partition_label, const esp_vfs_fat_mount_config_t *mount_config)
Convenience function to initialize read-only FAT filesystem and register it in VFS.
This is an all-in-one function which does the following:
finds the partition with defined partition_label. Partition label should be configured in the partition table.
mounts FAT partition using FATFS library
registers FATFS library with VFS, with prefix given by base_prefix variable
Note
Wear levelling is not used when FAT is mounted in read-only mode using this function.
- Parameters
base_path -- path where FATFS partition should be mounted (e.g. "/spiflash")
partition_label -- label of the partition which should be used
mount_config -- pointer to structure with extra parameters for mounting FATFS
- Returns
ESP_OK on success
ESP_ERR_NOT_FOUND if the partition table does not contain FATFS partition with given label
ESP_ERR_INVALID_STATE if esp_vfs_fat_spiflash_mount_ro was already called for the same partition
ESP_ERR_NO_MEM if memory can not be allocated
ESP_FAIL if partition can not be mounted
other error codes from SPI flash driver, or FATFS drivers
-
esp_err_t esp_vfs_fat_spiflash_unmount_ro(const char *base_path, const char *partition_label)
Unmount FAT filesystem and release resources acquired using esp_vfs_fat_spiflash_mount_ro.
- Parameters
base_path -- path where partition should be registered (e.g. "/spiflash")
partition_label -- label of partition to be unmounted
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if esp_vfs_fat_spiflash_mount_ro hasn't been called
-
esp_err_t esp_vfs_fat_info(const char *base_path, uint64_t *out_total_bytes, uint64_t *out_free_bytes)
Get information for FATFS partition.
- Parameters
base_path -- Base path of the partition examined (e.g. "/spiflash")
out_total_bytes -- [out] Size of the file system
out_free_bytes -- [out] Free bytes available in the file system
- Returns
ESP_OK on success
ESP_ERR_INVALID_STATE if partition not found
ESP_FAIL if another FRESULT error (saved in errno)
-
esp_err_t esp_vfs_fat_create_contiguous_file(const char *base_path, const char *full_path, uint64_t size, bool alloc_now)
Create a file with contiguous space at given path.
Note
The file cannot exist before calling this function (or the file size has to be 0) For more information see documentation for
f_expand
from FATFS library- Parameters
base_path -- Base path of the partition examined (e.g. "/spiflash")
full_path -- Full path of the file (e.g. "/spiflash/ABC.TXT")
size -- File size expanded to, number of bytes in size to prepare or allocate for the file
alloc_now -- True == allocate space now, false == prepare to allocate – see
f_expand
from FATFS
- Returns
ESP_OK on success
ESP_ERR_INVALID_ARG if invalid arguments (e.g. any of arguments are NULL or size lower or equal to 0)
ESP_ERR_INVALID_STATE if partition not found
ESP_FAIL if another FRESULT error (saved in errno)
-
esp_err_t esp_vfs_fat_test_contiguous_file(const char *base_path, const char *full_path, bool *is_contiguous)
Test if a file is contiguous in the FAT filesystem.
- Parameters
base_path -- Base path of the partition examined (e.g. "/spiflash")
full_path -- Full path of the file (e.g. "/spiflash/ABC.TXT")
is_contiguous -- [out] True == allocate space now, false == prepare to allocate – see
f_expand
from FATFS
- Returns
ESP_OK on success
ESP_ERR_INVALID_ARG if invalid arguments (e.g. any of arguments are NULL)
ESP_ERR_INVALID_STATE if partition not found
ESP_FAIL if another FRESULT error (saved in errno)
Structures
-
struct esp_vfs_fat_conf_t
Configuration structure for esp_vfs_fat_register.
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struct esp_vfs_fat_mount_config_t
Configuration arguments for esp_vfs_fat_sdmmc_mount and esp_vfs_fat_spiflash_mount_rw_wl functions.
Public Members
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bool format_if_mount_failed
If FAT partition can not be mounted, and this parameter is true, create partition table and format the filesystem.
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int max_files
Max number of open files.
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size_t allocation_unit_size
If format_if_mount_failed is set, and mount fails, format the card with given allocation unit size. Must be a power of 2, between sector size and 128 * sector size. For SD cards, sector size is always 512 bytes. For wear_levelling, sector size is determined by CONFIG_WL_SECTOR_SIZE option.
Using larger allocation unit size will result in higher read/write performance and higher overhead when storing small files.
Setting this field to 0 will result in allocation unit set to the sector size.
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bool disk_status_check_enable
Enables real ff_disk_status function implementation for SD cards (ff_sdmmc_status). Possibly slows down IO performance.
Try to enable if you need to handle situations when SD cards are not unmounted properly before physical removal or you are experiencing issues with SD cards.
Doesn't do anything for other memory storage media.
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bool use_one_fat
Use 1 FAT (File Allocation Tables) instead of 2. This decreases reliability, but makes more space available (usually only one sector). Note that this option has effect only when the filesystem is formatted. When mounting an already-formatted partition, the actual number of FATs may be different.
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bool format_if_mount_failed
Macros
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VFS_FAT_MOUNT_DEFAULT_CONFIG()
Type Definitions
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typedef esp_vfs_fat_mount_config_t esp_vfs_fat_sdmmc_mount_config_t