Mari 💫 👀

Mari is a lightweight wireless connectivity solution designed for dense IoT networks, with a focus on supporting real-time interactions and fast over-the-air (OTA) updates.

The driving use case for the design of Mari is the OpenSwarm Testbed of 1,000 DotBots. Mari is suitable for any dense IoT deployment requiring low-latency communication.

Key Features

• TSCH over BLE: Implements Time-Synchronized Channel Hopping (TSCH) over Bluetooth Low Energy (BLE) 2 Mbps PHY
• Multi-Gateway Architecture: Allows scaling the network by adding more gateways
• Non-Coordinated Gateways: Gateways are independent, so the infrastructure setup is very simple
• Fast Handovers: Enables quick transitions between gateways as nodes move
• Low-Power Operation: Designed for energy-efficient operation in battery-powered devices (BLE radio)
• Real-Time Communication: Achieves 100-150 ms average latency with 100 nodes per gateway
• Reasonable Throughput for OTAP: About 10 Kb/s downlink
• Quick Network Join: Best and worst -case join time of 150 ms and 6 seconds, respectively
• Dense Network Support: Scales for networks with hundreds to thousands of nodes

Project Structure

mari/
├── app/                    # Example applications and tests
│   ├── 03app_gateway/     # Gateway implementation example
│   ├── 03app_node/        # Node implementation example
│   └── ...                # Various test applications
├── drv/                   # Hardware drivers
├── mari/                  # Core protocol implementation
└── nRF/                   # Nordic Semiconductor SDK files

Example Usage

Gateway initialization:

mari_init(MARI_GATEWAY, MARI_NET_ID_DEFAULT, schedule, event_callback);

Node initialization:

mari_init(MARI_NODE, MARI_NET_ID_PATTERN_ANY, schedule, event_callback);

Hardware Support

Mari has been validated with the following Nordic Semiconductor chips:

• nRF52833
• nRF52840
• nRF5340

Development Environment

The project includes configuration files for:

• Segger Embedded Studio (.emProject files)
• Code formatting (.clang-format)
• Git hooks (.pre-commit-config.yaml)

Getting Started

[Coming soon]

License

This project is licensed under the terms included in the LICENSE file.

Publications

• Fedrecheski et al., "Mari: Connecting Large Scale Robot Swarms over BLE using TSCH with Multiple Independent Gateways", CrystalFreeIoT Workshop 2025 [Forthcoming]

Acknowledgments

This project has received funding from the EU's Horizon Europe Framework Programme under Grant Agreement No. 101093046.