Adafruit LittleFS for STM32¶

PORT · VENDORED · LOCAL PATH · BUILD_HEX

The STM32WL runs the same MeshCore code as the other platforms, but cannot use the LittleFS implementation from the nRF52 core. arch/stm32/ therefore holds a stripped-down version of that library, which enters the build through a local path.

[!NOTE] Source. This page was verified against the firmware itself: MeshCore v1.16.0, commit 03b6ef4, 28 July 2026 — files platformio.ini, arch/stm32/Adafruit_LittleFS_stm32/library.properties, arch/stm32/Adafruit_LittleFS_stm32/README.md and arch/stm32/build_hex.py.

What it does¶

LittleFS is a file system for flash memory: it spreads writes across the chip, copes with blocks that go bad and survives a power cut in the middle of a write. Adafruit wraps an Arduino layer around it as part of the nRF52 core, under the name Adafruit_LittleFS.

That wrapper is entangled with the nRF52 environment. The version in arch/stm32/ has been stripped of it; the directory's README.md describes that briefly and literally as: LittleFS from Adafruit, stripped of the things that keep it from compiling on STM32 — references to TinyUSB and FreeRTOS, mostly. The library.properties keeps version 0.11.0 and the original Adafruit provenance.

How MeshCore pulls it in¶

platformio.ini r.118-120

lib_deps = ${arduino_base.lib_deps}
  file://arch/stm32/Adafruit_LittleFS_stm32
  SubGhz

A local path: PlatformIO compiles the directory in as a library. There is no upstream to fetch from, no version range and no update path — what is in the repo is what you get.

The [stm32_base] section has a second peculiarity from the same directory:

platformio.ini r.111

extra_scripts = post:arch/stm32/build_hex.py

That script runs after the build and produces the .hex file the usual STM32 flashing tools expect.

How MeshCore uses it¶

The port is not called any differently from the nRF52 version. In the example sketches it runs in the same branch:

examples/companion_radio/main.cpp r.15-16

#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
  #include <InternalFileSystem.h>

That the two platforms share a line here is exactly what this port is for: the same include, the same class, a different implementation underneath.

Unlike on nRF52 there is no second volume on STM32 — EXTRAFS appears only in [nrf52_base]. See custom-lfs.md.

What it means for a node¶

An STM32WL node can keep settings, keys and contacts across a restart, just like an nRF52 node. That the firmware for that platform carries its own copy of the library also means improvements in the Adafruit version do not arrive here by themselves: that copy is updated by hand or not at all.

Sources¶

Translated from Dutch by Anthropic Claude