Building a solar powered Meshtastic node

Meshtastic is an open-source project that utilizes LoRa radios to create a long-range, off-grid communication network. It is particularly useful in areas with limited or no existing communication infrastructure, such as during outdoor adventures, emergencies, or in remote locations. An off-grid solar powered node could be deployed anywhere to act as a repeater, a sensor, or a tracker.

How it Works

Meshtastic radios utilize the LoRa protocol to communicate with each other. When a message is sent via the companion app (connected to the radio via Bluetooth, Wi-Fi, or serial), the radio broadcasts the message. Other radios in the mesh network receive and rebroadcast the message until it reaches its destination. Each message includes a hop limit to prevent infinite rebroadcasting. For a mesh to form, nodes must share the same LoRa channel settings, name and encryption key.

For full details of how Meshtastic works please refer to the Meshtastic website:

https://meshtastic.org/docs/introduction/

Building an off-grid Node

To build an off-grid, solar-powered Meshtastic node using the Wio Tracker L1, you'll need the Wio Tracker L1, a solar panel, a battery for backup power, and a suitable enclosure. The Wio Tracker L1 has built-in LoRa and GPS, making it suitable for Meshtastic networks. The RAK Unify enclosure provides weatherproof housing and has integral solar panels and antenna socket.

Components

• Wio Tracker L1: This development board provides the core functionality, including the nRF52840 microcontroller, LoRa transceiver, and GPS module.
• RAK Unify Enclosure with integrated Solar Panel and antenna socket: This provides a waterproof housing for the electronics as well as power from the integrated solar panel. The solar panel is rated at 5V out which is suitable to connect directly to the Wio Tracker L1.
• Battery: A battery pack made up of 2 18650 Lithium cells wired in parallel. The battery pack needs to have sufficient capacity to provide power during periods of low or no sunlight.
• 3D Printed Custom Mounting Plate for RAK enclosure (see attached .stl file)

Software

Download and flash the Meshtastic firmware onto the Wio Tracker L1. Configure the node with the desired settings, such as channel, region, and encryption. Connect to the Meshtastic App using Bluetooth.

Assembly

The RAK enclosure comes with a mounting plate and pre-installed weatherproof 5 pin connector on the bottom and an antenna connector on the top.

To make access to the enclosure easier, the bottom connector was removed and the 3D printed custom mounting plate installed.

The Wio Tracker L1 PCB was fitted. A double sided sticky pad was used to attach the GPS antenna to the inside of the enclosure.

The battery holders were fitted. Note the batteries are wired in parallel and the wires fitted with a 1.25mm pitch connector to match the socket on the Wio Tracker L1.

Insert Batteries (both the same way round), switch the node on, and pair it with your phone running the Meshtastic app. The screen will display a number that you need to type into your phone to pair the node.

Adding a Sensor

Whatever the intended end use of solar-powered Meshtastic node, adding one or more sensors via the Grove connector would be useful to either monitor the state of the node itself or to monitor the external environment.

Internal sensors such as BME680 could monitor conditions inside the enclosure to ensure temperature and humidity remain within acceptable limits. External sensors could be connected via the waterproof connector on the RAK Unify Enclosure to measure, for example, soil temperature and moisture content.

In this case a BME680 sensor was mounted inside the enclosure on the standoffs provided.

The connector on the bottom of the case was refitted and the wires tucked underneath the battery out of the way. This connector and wiring could be used to connect an external sensor if desired.

Finally attach the solar panel. The connecting wires from the solar panel on the RAK enclosure were fitted with a 2mm pitch connector to match the socket on the Wio Tracker L1.

The Meshtastic firmware will automatically detect any connected sensors, and "Sensor" mode can be set up using the Meshtastic App. Use the Telemetry module to choose what data is sent over the network and how often it is sent. There's an option to display the environmental data on the node itself - useful for checking everything is working ok before closing the case up.

Putting It All Together

Once you're happy that everything is working as it should, place the top on the enclosure making sure not to pinch any wires and screw it together.

Once up and running the Meshtastic app can be used to configure the node, display and log environmental and device data, and to send messages over the network.

Potential Applications

An off-grid, solar-powered Meshtastic node could be deployed in a number of ways including:

• Remote Repeater: Providing Meshtastic network access in remote locations
• Asset Tracking: GPS data sent over the Meshtastic network could be used for location tracking of any node. Although the enclosure is quite large, it would be useful to track high value assets such as construction or agricultural machinery
• Environmental Monitoring: Could be used to send data from sensors in remote locations. The Grove connector on the Wio Tracker L1 provides a convenient interface for many types of sensors.