littlefs File System Sample Application

Overview

This sample app demonstrates use of Zephyr’s file system API over littlefs, using a file system with a file that counts the number of times the system has booted. Other information about the file system is also displayed.

Requirements

The partition labeled “storage” will be used for the file system; see Flash map. If that area does not already have a compatible littlefs file system its contents will be replaced by an empty file system. You will see diagnostics like this:

[00:00:00.010,192] <inf> littlefs: LittleFS version 2.0, disk version 2.0
[00:00:00.010,559] <err> littlefs: Corrupted dir pair at 0 1
[00:00:00.010,559] <wrn> littlefs: can't mount (LFS -84); formatting

The error and warning are normal for a new file system.

After the file system is mounted you’ll also see:

[00:00:00.182,434] <inf> littlefs: filesystem mounted!
[00:00:00.867,034] <err> fs: failed get file or dir stat (-2)

This error is also normal for Zephyr not finding a file (the boot count, in this case).

Building and Running

This example should work on any board that provides a “storage” partition. Two tested board targets are described below.

You can set CONFIG_APP_WIPE_STORAGE to force the file system to be recreated.

NRF52840 Development Kit

On this device the file system will be placed in the SOC flash.

west build -b nrf52840dk_nrf52840 samples/subsys/fs/littlefs

Particle Xenon

On this device the file system will be placed on the external SPI NOR flash memory.

west build -b particle_xenon samples/subsys/fs/littlefs