SubGhz¶

STM32WL · NO SPI · FRAMEWORK LIBRARY · INCLUDE PATH

On every MeshCore platform the radio is a separate chip on the SPI bus. Not on the STM32WL: there it sits on the same die as the processor. The SubGhz library from the STM32duino core is the layer that makes that possible, and it arrives in a different way from every other library in this overview.

[!NOTE] Source. This page was verified against the firmware itself: MeshCore v1.16.0, commit 03b6ef4, 28 July 2026 — files platformio.ini, src/helpers/radiolib/CustomSTM32WLx.h and src/helpers/radiolib/CustomSTM32WLxWrapper.h.

What it does¶

The STM32WL is a microcontroller with an integrated sub-GHz radio. That radio is connected internally to the processor through its own SPI controller that never comes out to the pins. STM32duino's SubGhz library provides the access to it: it initialises that internal bus and supplies the low-level functions through which the radio core can be addressed.

The library is part of the framework-arduinoststm32 package. It is not in the PlatformIO registry and has no version number of its own.

How MeshCore pulls it in¶

Two lines are needed. First the include path, because the library lives inside the framework package:

platformio.ini r.115

  -I $PROJECT_PACKAGES_DIR/framework-arduinoststm32/libraries/SubGhz/src

And then the declaration itself:

platformio.ini r.120

  SubGhz

No author prefix and no version — like SPI and Wire this is a framework library. See wire-spi.md. Both lines sit in [stm32_base], so only the two wio-e5 variants get them.

How MeshCore uses it¶

Not directly. MeshCore talks to the radio core through RadioLib, which has the class STM32WLx and the module type STM32WLx_Module for it. The MeshCore-side part consists of a Custom class and a wrapper:

src/helpers/radiolib/CustomSTM32WLxWrapper.h r.1-9

#pragma once

#include "CustomSTM32WLx.h"
#include "RadioLibWrappers.h"
#include "SX126xReset.h"
#include <math.h>

class CustomSTM32WLxWrapper : public RadioLibWrapper {
public:

The STM32WL's radio core is related to the SX126x family, and it shows: the same SX126xReset.h that recalibrates a discrete SX1262 is used here too. In eleven of the 590 source files, SubGhz or STM32WL occurs.

What it means for a node¶

There are no radio pins to wire up and no P_LORA_* definitions to get right: the connection is inside the chip. That makes an STM32WL board simpler, and it is also why the platform is more constrained in other respects — there is less flash and less RAM than on the ESP32 and nRF52 boards.

The platform and its properties are described further in ../../platform/platform-families.md.

Sources¶

Translated from Dutch by Anthropic Claude