RTReticulum

Realtime Reticulum: a native Reticulum stack for microcontrollers.

WIP - RTReticulum is under active development. The core protocol (Identity, Destination, Packet, Link, Transport) works and interoperates with upstream Python Reticulum and real RNode hardware. Missing features include announce rate limiting, path expiry, ratchets, IFAC, Channel, and Buffer. See TODO for the full list.

A fast, power efficient, native Reticulum stack for embedded microcontrollers.

	RNode	microReticulum	RTReticulum
Autonomous node	No (host-driven modem)	Yes	Yes
NomadNet pages	No	No	Yes
WiFi + TCP bridge	No	No	Yes
BLE bridge	Bluedroid	No	NimBLE
OTA updates	No	No	Yes
Sleep	No (Arduino loop)	No	99% idle
Hardware crypto	No	No	mbedTLS accelerated
Radio driver	Arduino-LoRa	Arduino-LoRa	RadioLib (SX1262 native)

What works

• Full Reticulum protocol: Identity, Destination, Packet, Link, Transport with announce propagation and path discovery
• LoRa mesh: SX1262 via RadioLib: peer-to-peer encrypted Links over 915 MHz with automatic announce rebroadcast
• WiFi + TCP bridge: connect to an upstream rnsd instance to bridge LoRa traffic to the wider Reticulum network over the Internet
• NomadNet node: serves a live metrics page (uptime, battery, heap, RSSI, interfaces, known peers) that NomadNet users can browse
• RNode bridge: USB serial or Bluetooth LE KISS interface: the board acts as an RNode that Python Reticulum can drive directly
• All crypto in hardware: Ed25519, X25519, AES-256-CBC, HMAC-SHA256, HKDF, SHA-256/512 via mbedTLS + Monocypher
• 99% CPU idle in steady state, watchdog-clean boot

Supported hardware

Board	MCU	Radio	Status
Heltec WiFi LoRa 32 V3	ESP32-S3	SX1262	Primary target, fully working
Heltec WiFi LoRa 32 V4	ESP32-S3	SX1262 + PA/LNA	Port in progress
RAK3172 (STM32WLE5CC)	Cortex-M4F + SX1262 SoC	:	Port in progress

Build

RTReticulum uses Nix for reproducible builds. All toolchains (ESP-IDF, ARM GCC, host compilers, mbedTLS, Monocypher) come from flake.nix.

cd RTReticulum
nix develop

Firmware (Heltec V3)

cd firmware/heltec_v3

# Configure (optional: defaults work out of the box)
idf.py menuconfig

# Build
idf.py build

# Flash
idf.py -p /dev/ttyUSB0 flash

Firmware modes

The Heltec V3 firmware supports three operating modes, selectable via idf.py menuconfig under RTReticulum Heltec V3:

Transport node (default)

The board runs a full Reticulum stack with its own persistent Identity. It announces on LoRa and (if configured) bridges to the Internet via WiFi + TCP. It hosts a NomadNet-compatible page with live system metrics.

RNode bridge (USB UART)

The board exposes the SX1262 as an RNode over USB serial using the KISS protocol. Python Reticulum (rnsd, NomadNet, Sideband) can drive it directly with interface_type = RNodeInterface. The RTReticulum stack is not started: the board is a dumb radio modem.

RNode bridge (Bluetooth LE)

Same as the USB variant, but the KISS interface runs over a Nordic UART Service BLE GATT profile. Connect from Python RNS with port = ble://RNode XXXX. Adds NimBLE (~300 KB) to the firmware.

Configuration

WiFi and TCP bridge settings are under idf.py menuconfig → RTReticulum WiFi:

Setting	Description	Default
WIFI_DEFAULT_SSID	WiFi network name	empty (WiFi disabled)
WIFI_DEFAULT_PSK	WiFi password	empty
TCP_INTERFACE_HOST	Upstream rnsd IP/hostname	empty (TCP disabled)
TCP_INTERFACE_PORT	rnsd TCP port	4965
All settings can also be overridden at runtime via NVS (the firmware
checks NVS first, then falls back to menuconfig defaults).

Identity persistence

The node's 64-byte Ed25519+X25519 private key is stored in NVS on first boot and reused across reboots. The destination hash is stable: peers don't need to re-discover the node after a power cycle.

Credits

The Reticulum protocol implementation in RTReticulum is based on microReticulum by Chad Attermann, a C++ port of the Reticulum Network Stack by Mark Qvist. RTReticulum builds on microReticulum's protocol core (Identity, Destination, Packet, Link, Transport) and adapts it for FreeRTOS with hardware-accelerated crypto, RadioLib radio drivers, and power-managed embedded operation.