Meshtassy

Meshtassy is a mesh network that aims to be compatible with the Meshtastic network.

Overview

This project is a proof-of-concept implementation of a mesh network firmware using Embassy and lora-rs. It aims to be compatible with the Meshtastic network.

⚠️ This is currently a proof-of-concept and significant reorganization is likely in the future.

Supported Hardware

Currently supports:

• Seeed Studio XIAO nRF52840 with accompanying SX1262 LoRa module

The modular design of embassy-rs makes it relatively easy to port to other boards or Embassy-compatible platforms (ESP32, RP2040, etc.).

Features

Current Capabilities

• Decode most packets on primary channel
• Send packets on primary channel
• AES encryption/decryption for Meshtastic packets
• USB Serial implementation
• Protobuf message parsing for various Meshtastic message types:
  • Text messages
  • Telemetry data
  • Node info
  • Position data
  • Neighbor info
  • Traceroute

Near term goals

• Node database
  • RAM Node database
  • Persistence to Flash
  • Ability to specify nodedb size
• Channel database (support encrypting/decrypting other channels)
• Private messages (PKI encryption)
• Support for other Embassy-supported hardware (RP2040, ESP32 primarily, possibly others)

Longer term goals

• Support official Meshtastic clients
  • Initial connection, partial support
  • TODO: add more tasks here
• Serial support
• Bluetooth support
• WiFi support
• Support configuration (preferably without reboots, preferably support Meshtastic client managed config)
• Support multiple concurrent client connections
• Support public connection mode (only access public channels/read-only)
• Built-in Web Client

Project Structure

The project is organized into several crates:

nrf/

Main embedded application targeting the nRF52840. Contains the Embassy-based async runtime and LoRa radio management.

meshtassy-net/

Mesh network capabilities/integration.

Features:

• AES-CTR encryption compatible with Meshtastic network
• Header parsing and IV generation
• Support for variable key lengths (128/256bit, supporting meshtastic's default key and 1-byte keys, and 128/256bit keys)
• no_std compatible with optional defmt logging

meshtastic-protobufs/

Protobuf definitions and generated Rust code for Meshtastic messages.

Features:

• Generated from Meshtastic .proto files via git submodule
• Uses femtopb for no_std protobuf support and supports defmt

packet_creation_test/

Standalone test utility for validating packet creation and encryption without embedded hardware.

experiment/

Experimental code and tests (C implementations for comparison/validation).

Getting Started

Prerequisites

1. Install Rust with the ARM Cortex-M target:

   rustup target add thumbv7em-none-eabi

2. Install probe tools for flashing:

   • https://probe.rs/docs/getting-started/installation/

3. Hardware setup:

   • Seeed Studio XIAO rp2040 as picoprobe (can use any other probe-rs supported SWD tool)
     • connected to SWD pads on nRF52840
   • Seeed Studio XIAO nRF52840
   • Seeed Studio SX1262 LoRa module

Building and Flashing

cd nrf
cargo run

This will build the firmware and flash it to your connected nRF52840 device.

Configuration

Current LoRa configuration (in nrf/src/main.rs):

• Frequency: 906.875 MHz (US Meshtastic default)
• Spreading Factor: 11 (LongFast preset)
• Bandwidth: 250 kHz
• Coding Rate: 4/5
• Sync Word: 0x2B (Meshtastic standard)

Development

Testing

Run the standalone packet tests:

cd packet_creation_test
cargo test

Run crypto library tests:

cd meshtastic-crypto
cargo test

Adding Support for New Hardware

The repo will likely get restructured to better support multiple hardware devices, though some work has started on this.

For now, you'd probably want to copy the nrf directory and create an equivalent for a different board.

Protocol Compliance

The goal of the project is to be completely compatible with meshtastic firmware. This firmware may, however, add additional features on top of that using meshtastic's extra packet types and/or frequency switching.

License

This project is licensed under the GPL V3 - see LICENSE for details.

Acknowledgments

• Meshtastic - The original protocol and ecosystem
• Embassy - Async runtime for embedded Rust
• lora-rs - LoRa PHY implementation
• femtopb - No-std protobuf implementation
• gatlinnewhouse's rust firmware work - for the idea to use femptopb and random other ideas

Note: Meshtastic is a registered trademark of Meshtastic LLC. Meshtassy is not endorsed by or affiliated with Meshtastic/Meshtastic LLC.