.. _littlefs-sample:
littlefs File System Sample Application
#######################################
Overview
********
This sample app demonstrates use of Zephyr's :ref:`file system API
<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.
.. _littlefs:
https://github.com/ARMmbed/littlefs
Requirements
************
The partition labeled "storage" will be used for the file system; see
:ref:`flash_map_api`. 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.
.. zephyr-app-commands::
:zephyr-app: samples/subsys/fs/littlefs
:board: nrf52840dk_nrf52840
:goals: build
:compact:
Particle Xenon
==============
On this device the file system will be placed on the external SPI NOR
flash memory.
.. zephyr-app-commands::
:zephyr-app: samples/subsys/fs/littlefs
:board: particle_xenon
:goals: build
:compact:
3e73fc287e