RadioLib¶

TRANSCEIVER · GODMODE · EXCLUDE · WRAPPER

RadioLib is the layer between MeshCore and the radio chip. Six different transceivers are driven through it, each with its own wrapper in src/helpers/radiolib/. MeshCore does not use the library as intended: with RADIOLIB_GODMODE the internal registers are opened up, and fourteen items — six chip families and eight protocols — are stripped out at compile time.

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

What it does¶

RadioLib by Jan Gromeš is an Arduino library for wireless modules. It supports dozens of chips and a range of protocols — LoRa, FSK, but also AX.25, APRS, morse, RTTY and SSTV — behind a single interface. For every supported transceiver there is a class that handles the SPI commands, the register model and the timing of that specific chip. The documentation lives at github.com/jgromes/RadioLib and the API is extensively documented in that repository's wiki.

How MeshCore pulls it in¶

platformio.ini r.22

  jgromes/RadioLib @ ^7.6.0

The line sits in [arduino_base], so RadioLib is in all 507 build targets. The version range is open upwards within the 7.x series.

Two build flags steer how the library behaves:

platformio.ini r.27

build_flags = -w -DNDEBUG -DRADIOLIB_STATIC_ONLY=1 -DRADIOLIB_GODMODE=1

RADIOLIB_STATIC_ONLY forbids dynamic allocation inside the library. RADIOLIB_GODMODE makes all private and protected members public. That last one is not a debug option left behind: MeshCore needs it, as shown below.

RadioLib has no macro to switch a driver on. RadioLib.h r.76-124 includes every module driver and every protocol unconditionally, and each class sits behind a negative test in its own header — Morse.h r.1 opens with #if !defined(_RADIOLIB_MORSE_H) && !RADIOLIB_EXCLUDE_MORSE. An undefined macro is 0 in the preprocessor, so anyone who configures nothing compiles the complete library. Exclusion is the only knob the library offers. Why one library does it this way and another exactly the other way round is in ../library-configuration.md.

After that, fourteen items are excluded:

platformio.ini r.34-47

  -D RADIOLIB_EXCLUDE_CC1101=1
  -D RADIOLIB_EXCLUDE_RF69=1
  -D RADIOLIB_EXCLUDE_SX1231=1
  -D RADIOLIB_EXCLUDE_SI443X=1
  -D RADIOLIB_EXCLUDE_RFM2X=1
  -D RADIOLIB_EXCLUDE_SX128X=1
  -D RADIOLIB_EXCLUDE_AFSK=1
  -D RADIOLIB_EXCLUDE_AX25=1
  -D RADIOLIB_EXCLUDE_HELLSCHREIBER=1
  -D RADIOLIB_EXCLUDE_MORSE=1
  -D RADIOLIB_EXCLUDE_APRS=1
  -D RADIOLIB_EXCLUDE_BELL=1
  -D RADIOLIB_EXCLUDE_RTTY=1
  -D RADIOLIB_EXCLUDE_SSTV=1

Six of those exclude chip families MeshCore does not use, eight exclude protocols the library offers on top of the radio.

How MeshCore uses it¶

src/helpers/radiolib/ holds sixteen files. Six of them are pairs of a Custom* class and a Custom*Wrapper: LLCC68, LR1110, STM32WLx, SX1262, SX1268 and SX1276. The Custom* class inherits from the RadioLib class and adds what MeshCore misses; the wrapper translates that to the mesh layer's generic radio interface.

src/helpers/radiolib/CustomSTM32WLx.h r.8-16

class CustomSTM32WLx : public STM32WLx {
  public:
    CustomSTM32WLx(STM32WLx_Module *mod) : STM32WLx(mod) { }

    bool isReceiving() {
      uint16_t irq = getIrqFlags();
      bool detected = (irq & SX126X_IRQ_HEADER_VALID) || (irq & SX126X_IRQ_PREAMBLE_DETECTED);
      return detected;
    }
};

What GODMODE is needed for is shown by SX126xReset.h. To recalibrate an SX126x chip, MeshCore talks straight to RadioLib's module layer — mod and hal are not public in the library itself:

src/helpers/radiolib/SX126xReset.h r.13-18

  radio->mod->SPIwriteStream(RADIOLIB_SX126X_CMD_CALIBRATE, &calData, 1, true, false);
  radio->mod->hal->delay(5);
  uint32_t start = millis();
  while (radio->mod->hal->digitalRead(radio->mod->getGpio())) {
    if (millis() - start > 50) break;
    radio->mod->hal->yield();
  }

The text RadioLib occurs in 94 of the repo's 590 source files — by far the most of any library. The bulk of those are variants/ files that pick a RADIO_CLASS.

From the MeshCore wrapper classes through RadioLib to the transceiver: six
Custom wrapper pairs drive LLCC68, LR1110, SX1262, SX1268 and SX1276 over the
SPI bus, while the STM32WLx forms a separate branch sitting on the same chip
as the processor

What it means for a node¶

The choice of radio chip is a compile-time choice, not a setting. A variant sets RADIO_CLASS to the right Custom* class, and that fixes which transceiver the firmware can drive. Flash a board with the wrong variant and you get firmware that cannot find the radio.

The excluded protocols are simply not there: a MeshCore node cannot transmit APRS or morse, even though the library could in principle.

Sources¶

Translated from Dutch by Anthropic Claude