Learn by Hamming

Cool (non-ham) Project: Easy LoRa Node

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by

HamThings
in

I started my foray into the world of LoRa with a Heltec device in 2024. Very soon after, a friend gave me a commercial 900MHz antenna, so I started looking for an excuse to build another one. This generated a solar weather-indicating node which acts as a repeater, based on the RAK19007.

RAK19007-based LoRa node

It turns out the RAK-based node is so much more energy-efficient, at this point, I don’t see a reason to recommend a Heltec device! So, I went in search of a way to build a third node.

I accidentally tripped across an incredibly easy kit that I thought I’d share! My interest in LoRa focuses mainly on the Meshtastic project, so I’ll be approaching the build from that perspective.

The Parts

You will need the following:

  • One RAKwireless WisBlock Meshtastic Starter Kit
  • One 3.7V Lithium battery. I used a MakerFocus 3000mAh battery. It is obscenely overspecified for this project, but I had one laying around.
  • The correct adapter for the battery.
  • A bit of heat shrink tubing
  • The 3D printed parts for a RAK19007/RAK-5005 mini case. I used the front-noscreen-ribs (no GPS or power switch), RAK19007-mini frame no-user-button, a RAK-19007-mini button-reset-short and a back-12mm-battery-ribs.
  • PETG or ABS filament for printing. PLA will not survive even a warm spring day on a car dashboard. #askmehowiknow
  • Four 3mm x 20mm screws
  • Four 3mm nuts
  • A bit of tape. I used blue painter’s tape.

The Build

Print the case parts and do your best not to lose the button-reset-short. #askmehowiknow.

Cut the connector off the battery (WARNING: only cut one wire at a time or you’ll be in for a nasty surprise!) and solder the correct one (the bigger size) on.

Optionally (but preferred), roll a bit of tape sticky side out, and stick the battery into the case back.

Use the larger (2.5mm, I think) screws that came with the Meshtastic starter kit to screw the RAK19007 into the frame.

Feed the battery cable through the frame, but DO NOT connect it yet!

Install the u.fl to SMA pigtail into the frame, then attach the stubby antenna. Plug the u.fl connector into the LoRa port on the RAK19007 board.

Feed the Bluetooth antenna into its pocket and route its pigtail such that you can connect its u.fl connector to the BLE port on the RAK19007. Note: I chose NOT to stick the Bluetooth antenna down, in case I want to change cases later.

Now, you can plug in the battery. You should see a small green LED light up and start flashing, indicating that the RAK19007 is working.

Put the front on the node and screw everything together with the 3mm x 20mm screws.

Plug it in to USB-C to charge. If you used the 3000mAh battery like I did, you won’t have to charge your node again for at least two weeks, possibly closer to a month. Yup, I over-engineered my node. Whoops.

Configuration

Download a copy of the Meshtastic app for your device, turn on Bluetooth, and open the Meshtastic app.

Click the + button to add a new node. If you can’t add your node, go to your device’s Bluetooth settings and see if you need to pair it first.

Congratulations, you just joined the world of LoRa / Meshtastic!

A couple of common pitfalls as you play around with your configuration. Many of these are things which will cause other mesh users not to hate you:

  • PLEASE leave your node as ‘client’. Don’t change it to e.g. ‘repeater’ unless you know exactly what you are doing.
  • PLEASE leave MQTT off. MQTT is a way to see nodes that are connected to the Internet. This is neat in an area where there are very few nodes. If you can see even a few nodes, enabling MQTT will quickly swamp your local mesh network!
  • Don’t check the licensed amateur box, even though you likely are if you’re reading this. Checking it makes the firmware assume you’re running higher power than allowed under ISM (because you’re a ham), and automatically disables any encryption. In most cases, this isn’t worth it.

Final Thoughts

Meshtastic is a relatively new communication mode, which relies on messages being able to hop between devices. Unless you live in a very densely populated area, you likely won’t be able to use Meshtastic to communicate long distances. You may get lucky like I did, and find that several people near you have built nodes/gateways/repeaters, but I wouldn’t count on it.

Meshtastic is still a very young concept, and it will not be an effective form of communication until many more people adopt it. But, it sure is fun and inexpensive to play with, and it lets you tell people you’re an early adopter!