LittleFS for ESP-IDF.
LittleFS is a small fail-safe filesystem for microcontrollers. We ported LittleFS to esp-idf (specifically, the ESP32) because SPIFFS was too slow, and FAT was too fragile.
There are two ways to add this component to your project
- As a ESP-IDF managed component: In your project directory run
idf.py add-dependency joltwallet/littlefs==1.0.0
- As a submodule: In your project, add this as a submodule to your
components/directory.
git submodule add https://github.com/joltwallet/esp_littlefs.git
git submodule update --init --recursive
The library can be configured via idf.py menuconfig under Component config->LittleFS.
User @wreyford has kindly provided a demo repo showing the use of esp_littlefs. A modified copy exists in the example/ directory.
See the official ESP-IDF SPIFFS documentation, basically all the functionality is the
same; just replace spiffs with littlefs in all function calls.
Also see the comments in include/esp_littlefs.h
Slight differences between this configuration and SPIFFS's configuration is in the esp_vfs_littlefs_conf_t:
max_filesfield doesn't exist since we removed the file limit, thanks to @X-Ryl669partition_labelis not allowed to beNULL. You must specify the partition name from your partition table. This is because there isn't a definelittlefspartition subtype inesp-idf. The subtype doesn't matter.
At compile time, a filesystem image can be created and flashed to the device by adding the following to your project's CMakeLists.txt file:
littlefs_create_partition_image(partition_name path_to_folder_containing_files)
For example, if your partition table looks like:
# Name, Type, SubType, Offset, Size, Flags
nvs, data, nvs, 0x9000, 0x6000,
phy_init, data, phy, 0xf000, 0x1000,
factory, app, factory, 0x10000, 1M,
graphics, data, spiffs, , 0xF0000,
and your project has a folder called device_graphics, your call should be:
littlefs_create_partition_image(graphics device_graphics)
Here are some naive benchmarks to give a vague indicator on performance.
Formatting a ~512KB partition:
FAT: 963,766 us
SPIFFS: 10,824,054 us
LittleFS: 2,067,845 us
Writing 5 88KB files:
FAT: 13,601,171 us
SPIFFS*: 118,883,197 us
LittleFS**: 6,582,045 us
LittleFS***: 5,734,811 us
*Only wrote 374,784 bytes instead of the benchmark 440,000, so this value is extrapolated
**CONFIG_LITTLEFS_CACHE_SIZE=128
***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value)
In the above test, SPIFFS drastically slows down as the filesystem fills up. Below is the specific breakdown of file write times for SPIFFS. Not sure what happens on the last file write.
SPIFFS:
88000 bytes written in 1325371 us
88000 bytes written in 1327848 us
88000 bytes written in 5292095 us
88000 bytes written in 19191680 us
22784 bytes written in 74082963 us
Reading 5 88KB files:
FAT: 3,111,817 us
SPIFFS*: 3,392,886 us
LittleFS**: 3,425,796 us
LittleFS***: 3,210,140 us
*Only read 374,784 bytes instead of the benchmark 440,000, so this value is extrapolated
**CONFIG_LITTLEFS_CACHE_SIZE=128
***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value)
Deleting 5 88KB files:
FAT: 934,769 us
SPIFFS*: 822,730 us
LittleFS**: 31,502 us
LittleFS***: 20,063 us
*The 5th file was smaller, did not extrapolate value.
**CONFIG_LITTLEFS_CACHE_SIZE=128
***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value)
-
LittleFS operates on blocks, and blocks have a size of 4096 bytes on the ESP32.
-
A freshly formatted LittleFS will have 2 blocks in use, making it seem like 8KB are in use.
To flash the unit-tester app and the unit-tests, run
make tests
To test on an encrypted partition, add the encrypted flag to the flash_test partition
in partition_table_unit_test_app.csv. I.e.
flash_test, data, spiffs, , 512K, encrypted
Also make sure that CONFIG_SECURE_FLASH_ENC_ENABLED=y in menuconfig.
The unit tester can then be flashed via the command:
make TEST_COMPONENTS='src' encrypted-flash monitor
- July 22, 2020 - Changed attribute type for file timestamp from
0to0x74('t' ascii value).
This code base was heavily modeled after the SPIFFS esp-idf component.