Experimenting with Meshtastic on 433MHz with MQTT Bridging

Introduction

Beyond using LilyGO modules for LoRa APRS, I’ve been exploring their capabilities with Meshtastic. While experimenting, I quickly realized that most Meshtastic nodes in Europe operate on 868MHz, making it impossible to connect my 433MHz nodes directly to an existing network. However, MQTT provided an alternative solution, allowing me to bridge my nodes to the wider Meshtastic ecosystem. This article details my technical setup and how MQTT enables interoperability across different frequencies.

Node Configuration

I set up two different Meshtastic nodes:

1. LilyGO T3 V2.1 (Home Node) – Configured as a client with WiFi and MQTT enabled.
2. LilyGO T-Beam (Mobile Node) – Configured as a mobile unit with GPS, operating in client_mute mode to optimize hop efficiency.

Home Node (LilyGO T3 V2.1)

The home node acts as a gateway between the local LoRa network and MQTT. The setup involved the following configurations:

• Network Mode: client (WiFi-enabled)
• MQTT: Enabled
• Primary Channel: Up and Downlink enabled
• WiFi Connection: Configured to connect to my home network

Once the MQTT connection was established, the node started receiving messages from the primary default Meshtastic channel. These messages were then forwarded to the MQTT broker.

Mobile Node (LilyGO T-Beam)

The mobile node, equipped with a GPS module, needed a different configuration:

• Mode: client_mute (prevents retransmitting messages, saving hops)
• MQTT: Enabled
• Primary Channel: Up and Downlink enabled
• Ignore MQTT: Off
• OK to MQTT: On

In this configuration, the home node receives and transmits messages over the LoRa network and forwards them to the MQTT server. The mobile node, despite being on 433MHz, can still send and receive messages if the home node picks them up and forwards them via MQTT.

Bridging Different Frequency Networks with MQTT

One major limitation of operating on 433MHz in Europe is the lack of existing nodes. To work around this, I set up my home node as an MQTT bridge. This means:

• The home node connects to the internet and the MQTT broker.
• Any messages received on the 433MHz frequency are forwarded to MQTT.
• The mobile node can receive MQTT-broadcasted messages from the home node.
• Messages from the mobile node are picked up by the home node and forwarded to MQTT.

By setting an appropriate topic structure in the MQTT broker, I can connect to Meshtastic users worldwide who also use MQTT. However, it is important to note that messages received from MQTT are only transmitted one hop over LoRa, regardless of the node’s settings.

Alternative Setup: Mobile Node with Direct MQTT

Another approach would be to enable MQTT on the mobile node and have it use the host device’s internet connection as a proxy. This would allow direct MQTT connectivity without requiring a dedicated home node. However, I prefer a central node that acts as a bridge between my mobile nodes and MQTT.

Future Enhancements

Currently, my setup is still in the experimental phase:

• Hardware Enclosure: I plan to design a case for my home node, including proper ventilation and environmental protection.
• Power Management: Integration of a solar panel, battery, and charge controller for continuous outdoor operation.
• Antenna Upgrades: A better antenna for improved reception and transmission.
• Dedicated MQTT Server: Instead of relying on public brokers, I will set up my own MQTT server to manage message routing.

Once complete, my home node will run 24/7 as a dedicated 433MHz Meshtastic gateway, the first in my region.

Conclusion

This experiment demonstrates how MQTT can be leveraged to bridge frequency gaps in Meshtastic networks. My setup allows a 433MHz network to integrate with the broader Meshtastic ecosystem, making long-distance communication feasible even when no local nodes exist.

If you are experimenting with Meshtastic on 433MHz or interested in using my MQTT bridge, feel free to reach out!