Little File System (LittleFS) Usage Scenarios#

The Little File System (LittleFS) is a lightweight, fault-tolerant file system designed for microcontrollers with limited memory and flash storage.
It supports wear leveling, crash recovery, and power-failure resilience, making it ideal for embedded applications that require robust and compact file storage.

The following scenarios demonstrate common ways to use LittleFS in embedded device development, including for SiWx917-based applications.

1. Storing Configuration Files#

Many embedded systems must retain configuration settings across power cycles.

With LittleFS, configuration files such as network credentials, security settings, and device parameters can be created, updated, and safely retained even after system resets.

//Config
WifiConfig_t myConfig = {
    .ssid = "MyNetwork",
    .password = "MySecurePassword",
    .securityMode = 2 
};

//Function to store configs
lfs_file_open(&lfs, &file, "config.bin", LFS_O_WRONLY | LFS_O_CREAT | LFS_O_TRUNC);
lfs_file_write(&lfs, &file, &myConfig, sizeof(myConfig));
lfs_file_close(&lfs, &file);

2. Data Logging and Storage#

Many embedded systems require continuous recording of data, such as sensor readings, event logs, or performance metrics.

LittleFS provides a fault-tolerant and wear-leveled mechanism for writing this information to internal or external flash memory.

It allows developers to build long-term logging systems without the need for external storage hardware.

Example Applications:

  • Environmental monitoring systems recording temperature, humidity, and air quality.

  • Power management devices logging current and voltage readings.

  • Industrial controllers tracking runtime statistics and operational errors.

Advantages:

  • Reliable data persistence with journaling and power-fail recovery.

  • Efficient wear leveling, ensuring extended flash lifetime.

  • Compact footprint, ideal for MCU-based logging without SD cards or EEPROMs.

Tip: Use rolling log files or segmented file naming (such as, log_01.txt or log_02.txt) to manage long-term data efficiently.

3. Web Server Content Hosting#

When developing connected or IoT devices, LittleFS can serve as onboard storage for hosting web interfaces such as configuration portals or dashboards.

Web assets such as HTML, CSS, JavaScript, and images can be stored directly in flash and served via an embedded web server.

Example Applications:

  • A Wi-Fi-enabled thermostat hosting a web-based temperature control panel.

  • A networked sensor node providing local access to real-time data through a web dashboard.

  • A smart plug or lighting device exposing a configuration interface through an onboard web server.

Advantages:

  • Eliminates the need for an external file server.

  • Enables local web configuration and monitoring.

  • Provides fast and persistent access to UI assets from internal flash.

Best Practice: Compress web resources before flashing (for example, minified .js or .css files) to save space and improve load performance.

4. Small Data Storage#

When using external storage (for example, microSD cards) is not feasible, LittleFS offers a lightweight alternative for persistent storage.
It allows storing small datasets, logs, or device states directly on the MCU’s internal flash memory, offering durability and simplicity.

Example Use Cases:

  • Storing application logs and debug information.

  • Retaining state variables (for example, relay status or last sensor reading).

  • Saving short-term diagnostic data for system recovery.

Advantages:

  • Compact design with low memory overhead.

  • Eliminates the need for additional storage hardware.

  • Reliable persistence across reboots or firmware updates.

Tip: Use LittleFS for storing temporary diagnostic files, event records, or firmware logs in small, structured formats.

5. Managing Application Resources#

LittleFS can be used to store binary assets and application resources such as:

  • UI elements (icons, fonts, and images)

  • Audio clips or prompts

  • Localization files or configuration templates

Storing assets in flash memory simplifies resource management and ensures quick, predictable access to data during runtime.

Example Applications:

  • Display-based IoT devices storing user interface graphics and fonts.

  • Voice-enabled assistants retaining audio clips and localized prompts.

  • Embedded GUIs requiring immediate access to icons or style elements.

Advantages:

  • Centralized management of critical application resources.

  • Fast access times for media and UI elements.

  • Simplified integration into embedded user interfaces.