SPIFFS is a file system intended for SPI NOR flash devices on embedded targets. It supports wear leveling, file system consistency checks and more.
- Currently, SPIFFS does not support directories. It produces a flat structure. If SPIFFS is mounted under
/spiffs, then creating a file with path
/spiffs/tmp/myfile.txtwill create a file called
/tmp/myfile.txtin SPIFFS, instead of
- It is not a realtime stack. One write operation might last much longer than another.
- Currently, it does not detect or handle bad blocks.
spiffsgen.py is a write-only Python SPIFFS implementation used to create filesystem
images from the contents of a host folder. To use
spiffsgen.py, simply invoke it from your favorite terminal:
python spiffsgen.py <image_size> <base_dir> <output_file>
- image_size: size of the partition on which the created SPIFFS image will be flashed to
- base_dir: directory to create the SPIFFS image of
- output_file: SPIFFS image output file
Besides the three required arguments: image_size, base_dir and output_file, there are other arguments that control image generation. Documentation on these arguments exist in the tool’s help:
python spiffsgen.py --help
These optional arguments correspond to possible SPIFFS build configuration. User should make sure that the image is generated with the same arguments/configuration as SPIFFS was built with, else the user ends up with an invalid image. As a guide, the help output indicates the SPIFFS build configuration the argument corresponds to. In cases when these arguments are not specified, the default values shown in the help output are used.
Once the image has been created, it can be flashed using
Aside from invoking
spiffsgen.py standalone, it is also possible to use it directly from the build system by calling
$(eval $(call spiffs_create_partition_image,<partition>,<base_dir>,[FLASH_IN_PROJECT]))
spiffs_create_partition_image(<partition> <base_dir> [FLASH_IN_PROJECT])
This is more convenient as the build configuration is automatically passed to the tool,
ensuring that the image generated is valid for that build. An example of this is while the image_size is required
for the standalone invocation, only the partition name is required when using
the image size is automatically obtained from the project’s partition table.
It is important to note that due to the differences in structure between the two build systems,
when using Make,
spiffs_create_partition_image must be called from the project Makefile;
for CMake, it should be called from one of the component CMakeLists.txt. For both build systems, the image will be created in the build directory
with filename partition.bin.
Optionally, user can opt to have the image automatically flashed together with the app binaries, partition tables, etc. on
idf.py flash or
make flash by specifying
FLASH_IN_PROJECT. For example:
spiffs_create_partition_image(my_spiffs_partition my_folder FLASH_IN_PROJECT)
If FLASH_IN_PROJECT is not specified, the image is still generated,
but user has to flash it manually using
parttool.py or a custom build system target.
For an example, see examples/storage/spiffsgen>.
Another tool for creating SPIFS partition images is mkspiffs.
spiffsgen.py, it can be used to create image from a given folder and then flash that image with
To do that you need to obtain some parameters:
- Block Size: 4096 (standard for SPI Flash)
- Page Size: 256 (standard for SPI Flash)
- Image Size: Size of the partition in bytes (can be obtained from partition table)
- Partition Offset: Starting address of the partition (can be obtained from partition table)
To pack a folder into 1 Megabyte image:
mkspiffs -c [src_folder] -b 4096 -p 256 -s 0x100000 spiffs.bin
To flash the image to ESP32 at offset 0x110000:
python esptool.py --chip esp32 --port [port] --baud [baud] write_flash -z 0x110000 spiffs.bin
Notes on which SPIFFS tool to use¶
The two tools presented above offer very similar functionality. There are, however, reasons to prefer one over the other depending on the use case.
If the intent is to simply generate a SPIFFS image during build,
spiffsgen.py makes it very convenient
by providing functions/commands from the build system itself. This makes it easy to generate SPIFFS images
that match the build configuration and can be flashed together with the application.
Another case for choosing
spiffsgen.py is when the host has no C/C++ compiler available, since
On the other hand,
mkspiffs offers unpacking SPIFFS images in addition to image generation. This is not
spiffsgen.py, at least not yet. There might also be environments where a Python interpreter
is not available, but a host compiler is or a pre-compiled
can do the job. However, there is no build system integration for
mkspiffs and the user has to
do the corresponding work: compiling
mkspiffs during build (if a pre-compiled binary is not used), creating build rules/targets
for the output files, passing proper parameters to the tool, etc.
An example for using SPIFFS is provided in storage/spiffs directory. This example initializes and mounts SPIFFS partition, and writes and reads data from it using POSIX and C library APIs. See README.md file in the example directory for more information.
High level API Reference¶
esp_vfs_spiffs_register(const esp_vfs_spiffs_conf_t *conf)¶
Register and mount SPIFFS to VFS with given path prefix.
- ESP_OK if success
- ESP_ERR_NO_MEM if objects could not be allocated
- ESP_ERR_INVALID_STATE if already mounted or partition is encrypted
- ESP_ERR_NOT_FOUND if partition for SPIFFS was not found
- ESP_FAIL if mount or format fails
conf: Pointer to esp_vfs_spiffs_conf_t configuration structure
esp_vfs_spiffs_unregister(const char *partition_label)¶
Unregister and unmount SPIFFS from VFS
- ESP_OK if successful
- ESP_ERR_INVALID_STATE already unregistered
partition_label: Optional, label of the partition to unregister. If not specified, first partition with subtype=spiffs is used.
esp_spiffs_mounted(const char *partition_label)¶
Check if SPIFFS is mounted
- true if mounted
- false if not mounted
partition_label: Optional, label of the partition to check. If not specified, first partition with subtype=spiffs is used.
esp_spiffs_format(const char *partition_label)¶
Format the SPIFFS partition
- ESP_OK if successful
- ESP_FAIL on error
partition_label: Optional, label of the partition to format. If not specified, first partition with subtype=spiffs is used.
esp_spiffs_info(const char *partition_label, size_t *total_bytes, size_t *used_bytes)¶
Get information for SPIFFS
- ESP_OK if success
- ESP_ERR_INVALID_STATE if not mounted
partition_label: Optional, label of the partition to get info for. If not specified, first partition with subtype=spiffs is used.
total_bytes: Size of the file system
used_bytes: Current used bytes in the file system
Configuration structure for esp_vfs_spiffs_register.
const char *
File path prefix associated with the filesystem.
const char *
Optional, label of SPIFFS partition to use. If set to NULL, first partition with subtype=spiffs will be used.
Maximum files that could be open at the same time.
If true, it will format the file system if it fails to mount.
- const char *