LittleFS for ESP-IDF.

What is LittleFS?

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.

How to Use

In your project, add this as a submodule to your components/ directory.

git submodule add https://github.com/joltwallet/esp_littlefs.git

The library can be configured via make menuconfig under Component config->LittleFS.

Documentation

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

Performance

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:       14,711,396 us
SPIFFS:   154,238,375 us
LittleFS:  10,344,878 us

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 6945139 us
88000 bytes written in 6945135 us
88000 bytes written in 11090827 us
88000 bytes written in 27832679 us
22784 bytes written in 101424595 us

Deleting 5 88KB files:

FAT:      1,216,137 us
SPIFFS:   3,712,190 us
LittleFS:    32,827 us

Tips, Tricks, and Gotchas

• 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.

Running Unit Tests

To flash the unit-tester app and the unit-tests, run

make tests

Acknowledgement

This code base was heavily modeled after the SPIFFS esp-idf component.