LighthouseReckoning: A Lightweight LoRa Mesh Network for Arduino, ESP32 and RP2040

LighthouseReckoning is a compact LoRa mesh networking library tailored for Arduino-compatible microcontrollers, specifically tested on ESP32 and RP2040 platforms utilizing SX126x LoRa radios. The main objective is to enable seamless communication from sensors to relays, ultimately reaching the home node. Each node in the network only needs to know its distance to the home node, with information about distance exchanged during node interactions. This eliminates the need for nodes to have complete knowledge of the network topology.

Routing is achieved through hop-by-hop confirmations rather than end-to-end acknowledgements. For instance, if Sensor C needs to transmit data to the home, it first sends the information to Relay A, which then forwards it to Relay B before finally reaching the home node. Sensor C only waits for confirmation that Relay A successfully received its packet, allowing each node to independently handle retries. This approach enhances efficiency and local problem-solving within the network.

Initializing a basic node involves including the necessary libraries, setting up the LoRa radio, and calling lhr.beginAsNode() with the appropriate parameters. Communication from the node occurs through the loop function, where lhr.update() and lhr.sendData() are utilized to maintain the network's functionality. The Home node, on the other hand, employs beginAsHome() and receives application data via the library's callback mechanism.

The library is designed to be non-blocking, allowing the update() function to be called repeatedly in the main loop without interruption. Features include automatic multi-hop routing, home-based distance-vector routing, hop-by-hop confirmations, local packet retries, duplicate detection, TTL protection, non-blocking operation, and optional duty-cycle limiting. LighthouseReckoning supports ESP32, RP2040, and SX126x LoRa radios through RadioLib. Currently, the library has been validated with ESP32, RP2040, and SX1262 radios.

Looking ahead, future updates will focus on enhancing the routing and reliability aspects, incorporating additional protocol features, improving security, and expanding hardware testing. The complete source code, protocol documentation, examples, and field-test data are accessible on GitHub. Feedback and suggestions from those working with LoRa, embedded networking, ESP32, RP2040, or distributed sensor networks are greatly appreciated.