Mesh Network Protocol for embedded devices

Goal

The goal of this project is to create easy to use, mesh like, data transferring protocol using cheap components (Arduino with atmega 328p chip, but not only, and any radio module with USART interface, which allows duplex data transfer). This protocol allows you to build a reliable and easy-to-use mesh-like network for various applications, such as:

• Home automation
• Remote control
• Remote monitoring (telemetry)
• Decentralized messaging

While initially designed to be able to run on Atmega328p chips, so as well as it runs on this platform - it can be ported to many other platforms, which are supported by embedded-hal.

Potentially this protocol can be run on other platforms. (arduino nano, linux are supported) It is done by generic behaviour being moved out of implementation to make it interchangable with implementations of PlatformTime and PlatformSerial traits for each other platform.

The code is designed to utilize UART rx/tx pins of your MCU and has been tested with popular radio modules JDY-40. The code potentially can use radio modules with similar UART interface, that devices, such as:

• JDY-41
• SV-610
• HC-11
• HC-12
• LC12S
• GT-38
• LoRa modules

Status

The following functionalities of protocol have been tested and verified:

• Send data.
• Receive data.
• Send data with ignorance of duplicated packets.
• Send data with limited of number of hops.
• Multicast data to all nodes.
• Message transition by the intermediate nodes.
• Send message with ping flag, and receive message with pong flag set.
• Transaction send and receive packet about transaction being finished.

Cross-platform compatibility

The library runs natively on Arduino nano board and Linux. The communication is tested between Arduino nano board and Linux.

Porting to other platforms

This library is relatively easy to be ported to other platforms. To port this library to your platform - you just have to implement PlatformTime and PlatformSerial traits for your platform.

These are two generic interfaces.

• The library uses PlatformSerial interface to communicate with radio module over USART.
• The library uses PlatformTime interface to be able to keep track of time.

In case, if implementations are already present for platform, you need - you just simply include those and use them into your project.

PlatformSerial and PlatformTime interfaces implemented for Arduino nano board.

The implementation of PlatformSerial for Arduino nano board is done by:

• platform-serial-arduino-nano

The implementation of PlatformTime for Arduino nano board is done by:

• platform-millis-arduino-nano

Sometimes code binary might not fit onto your arduino board memory, in order to reduce the size of final binary - it is recommended to compile it with --release flag.

Examples can be found here:

• arduino-nano

PlatformSerial and PlatformTime interface for Linux.

The implementation of PlatformSerial for Linux is done by:

• platform-serial-linux

The implementation of PlatformTime for Linux is done by:

• platform-millis-linux

Examples can be found here:

• linux

Reduce packet collisions

It is recommended to set listen_period value on multiple devices different from each other, like:

• device 1 - 130 ms,
• device 2 - 150 ms,
• device 3 - 140 ms this will reduce chance of the network to sychronize, which will lead to packet collisions.

Note: The higher count of nodes in the network leads to the more network stability. In the stable networks - there is less need to use transaction or ping_pong sending, unless, you send something very important.

Warning

This protocol does not provide data encryption. To secure your data from being stolen, you should implement (de/en)cryption mechanisms independently.

Main Components

The central component of this protocol is the Node structure, which offers a user-friendly interface for actions like send, receive, multicast, ping-pong, and send message with transaction. The Node should be constantly updated by call its update method, it - does all internal work:

• routes packets
• transits packets that were sent to other devices
• handles special packets like ping and pong, or any kind of transaction one. and so on.

To initialize a Node, you need to provide two values:

• AddressType: Represents the device's identification address in the node pool.
• listen_period: A value in milliseconds that determines how long the device will wait before transmitting on the network to prevent network congestion.

You can regulate the number of hops that the packet will be able to make - by configuring the lifetime during making the send of the message. For example:

• setting lifetime to 1 will limit the message's reach to the nearest devices in the network.
• setting lifetime to 10 will make the packet able to pass 10 nodes before being destroyed.

To send the message to all nodes in the network, you can send it with standard send method, and put MULTICAST_RESERVED_IDENTIFIER as the destination_device_identifier. Every device will treat MULTICAST_RESERVED_IDENTIFIER as it's own address, will keep the message as received and will transit copy of that message further. Note! That you are not allowed to use MULTICAST_RESERVED_IDENTIFIER in the send_ping_pong or send_with_transaction methods, it will jam your network with packets.

The term "echoed message" refers to a duplicated message that has been re-transmitted into the ether by an intermediate device.

Send Method

The send method requires the following arguments:

• data: A PacketDataBytes instance to hold the message bytes.
• destination_device_identifier: A AddressType instance indicating the target device.
• lifetime: A LifeTimeType instance to control for how long the message can travel.
• filter_out_duplication: A boolean flag to filter out echoed messages from the network.

Receive Method

The receive method optionally returns received data in a PacketDataBytes instance.

Send Ping-Pong Method

The send_ping_pong method sends a message with a "ping" flag to the destination node and waits for the same message with a "pong" flag. It returns an error if the ping-pong exchange fails. The following arguments are required:

• data: A PacketDataBytes instance.
• destination_device_identifier: A AddressType instance.
• lifetime: A LifeTimeType instance.
• filter_out_duplication: A boolean flag to filter out echoed messages from the network.
• timeout: An ms instance specifying how long to wait for a response.

Send with Transaction Method

The send_with_transaction method sends a message and handles all further work to ensure the target device have received it correctly. It returns an error if the transaction failed. The required arguments are:

• data: A PacketDataBytes instance.
• destination_device_identifier: A AddressType instance.
• lifetime: A LifeTimeType instance.
• filter_out_duplication: A boolean flag to filter out echoed messages from the network.
• timeout: An ms instance to specify the response wait time.

Note

Under the hood, data is packed into a Packet instance. If you need customize packets - you can configure the Packet fields in src/Node/packet/config.rs and src/Node/packet/types.rs. Also serialization and deserealization part will be touched too.

Compatibility

All nodes must have the same version of the protocol installed to communicate. Different implementations of the Packet structure, or serialization or deserealization methods will lead to communication issues.

Getting Started

You can use this either as a library or by modification of code of example in the exmaples directory.

License

This project is licensed under:

• GNU General Public License, Version 3.0 (LICENSE-GPL or GPL License)
• Apache License, Version 2.0 (LICENSE-APACHE or Apache License 2.0)
• MIT License (LICENSE-MIT or MIT License)

You can choose the license that best suits your preferences.

Contribution

Unless you specify otherwise, any contributions submitted for inclusion in this project, as defined in the Apache-2.0 license, will be dual-licensed under both licenses without additional terms or conditions.

Donation

Also you can support the project by donating few bucks on the bitcoin address: bc1qc50tm0ppj3hh7fecd6d0rv8tdygy8uhe2cemzt