Building a MeshCore MQTT Bridge: A Journey into Radio Packets and tiny Raspberry Pis

Introduction: Why Would Anyone Do This?

So you’ve decided to join the ranks of the enlightened few who run MeshCore nodes. Excellent choice! But now you want to take it a step further. You want your mesh network data flowing like a digital river into an MQTT broker, where it can be slurped up by Home Assistant, logged to a database, or simply admired in all its JSON glory.

Welcome to the world of the MeshCore MQTT bridge, where a LoRa Node board and a Raspberry Pi 2W join forces to become the Swiss Army knife of mesh networking. This setup lets your mesh node chat with the wider world of IoT devices, automation systems, and whatever other nerdy contraptions you’ve got running in your ham shack (or living room, no judgment).

What You’ll Need:

One LoRa Node board (Heltec V4, RAK Wisblock, etc. this is the hardware that’ll do the actual radio work)
One Raspberry Pi 2W (the brains of the operation)
One Micro SD card (32Gb or larger)
A USB cable to connect them (because wireless is overrated when you’re literally sitting on a desk)
Patience (more than you think, less than kernel compilation)
Coffee (optional but highly recommended)

Part 1: Preparing Your Raspberry Pi (The Foundation)

Think of your Raspberry Pi as a tiny Linux computer that costs less than a large pizza. We’re going to turn it into an MQTT bridge, which is basically a translator that speaks both MeshCore and MQTT. It’s bilingual, if you will.

Step 1: Install Python Dependencies (aka The “Do This First or Suffer Later” Step)

Here’s where most tutorials bury the lede, but not us. We’re going to install the Python packages FIRST, before anything else. Why? Because Python’s virtual environments can be fussy little things, and the MQTT server software we’ll install later has opinions about where things should live.

Fire up your Raspberry Pi’s terminal and run this command:

python3 -m pip install pyserial paho-mqtt --break-system-packages

“Wait, did you just tell me to use --break-system-packages? That sounds terrifying!”

I hear you. It does sound like the flag equivalent of “hold my beer.” But here’s the deal: modern Debian-based systems (which includes Raspberry Pi OS) have gotten very protective about their Python environments. They don’t want you polluting the system Python with random packages. Normally, that’s good advice! But in this case, we’re intentionally installing these packages system-wide because our MQTT bridge service needs to access them.

The two packages we’re installing are:

pyserial: This lets Python talk to serial devices (like your LoRa Node board over USB)
paho-mqtt: This is the MQTT client library that handles all the publish/subscribe magic

Part 2: Configuring Your Node (The Radio Part)

Your LoRa Node is the device that actually communicates with the mesh network. It’s got a radio, a processor, and dreams of being more than just a fancy packet repeater. We’re going to make those dreams come true by flashing it with custom firmware that knows how to play nice with our MQTT bridge.

Step 2A: Download Custom MQTT Firmware

Head over to the Custom MQTT Software page to download the special firmware that turns your node into an MQTT-aware mesh node.

“Why do I need special firmware?”

Great question! The standard MeshCore firmware is designed to be a mesh node and nothing more. This custom firmware adds the ability to output structured data over the serial connection in a format that our MQTT bridge can understand. It’s like teaching your node a new language specifically for talking to computers instead of just other radios.

Step 2B: Flash Your LoRa Node

Once you’ve downloaded the firmware file (it’ll probably be a .bin file with an intimidating name full of version numbers), it’s time to flash your board. Don’t worry, this is easier than it sounds.

Navigate to the MeshCore Web Flasher and follow these steps:

Connect your node to your computer via USB
- Use a good quality USB cable (this is not the time for that sketchy gas station cable)
- You might need to hold down the “BOOT” button on your node while plugging it in to enter flash mode
Use the web flasher interface
- Scroll to the bottom of the page
- Click the “Custom Firmware” at the bottom left of the page
- Select the firmware file you just downloaded
- Click the flash button and wait (usually takes 30-60 seconds)
- Watch the progress bar like it’s the most exciting thing you’ve seen all day (because right now, it is)
Verify the flash completed successfully
- The web flasher should give you a success message
- Your node might restart automatically

Troubleshooting: If the web flasher doesn’t detect your device, try:

A different USB port
A different USB cable (seriously, cables are often the problem)
Holding the BOOT button while connecting
Sacrificing a small offering to the IoT gods

Step 2C: Connect to Your Raspberry Pi

Once your node is flashed, disconnect it from your computer and connect it to your Raspberry Pi 2W via USB. The Pi should detect it as a serial device (usually /dev/ttyUSB0 or /dev/ttyACM0).

You can verify this by running:

ls /dev/tty*

Look for something that wasn’t there before you plugged in the node.

Step 2D: Install the MQTT Bridge Software

Now that we’ve laid the groundwork, it’s time to install the actual bridge software. This is the piece of code that will read data from your MeshCore node via serial connection and forward it to your MQTT broker.

Unfortunately, the specific installation instructions for the MQTT bridge software vary depending on which implementation you’re using. You’ll want to:

Run this command: curl -fsSL https://raw.githubusercontent.com/Cisien/meshcoretomqtt/main/install.sh | bash
Install any additional dependencies it requires
Configure the connection settings (serial port, MQTT broker address, etc.)
Follow the prompts.

Pro tip: Make sure you know where your mctomqtt.py file (or equivalent bridge script) lives. You’ll need this path later for the crontab setup.

Part 3: Making It All Automatic (The “Set It and Forget It” Step)

Now we get to the magical part where we make everything start automatically when your Raspberry Pi boots up. No more SSH-ing in and manually starting scripts like some kind of caveman. We’re going to use cron, which is Linux’s built-in task scheduler (and one of the oldest pieces of Unix software that still gets used daily).

Step 3A: Set Up Your Crontab

Open your crontab for editing:

crontab -e

If this is your first time running this command, it might ask you to choose an editor. Pick nano if you’re unsure (it’s the friendliest one).

Add the following lines to your crontab:

PATH=/home/w6sal/.nvm/versions/node/v24.11.1/bin:/usr/local/bin:/usr/bin:/bin
@reboot sleep 120 && /home/w6sal/meshcoretomqtt/venv/bin/python3 /home/w6sal/meshcoretomqtt/mctomqtt.py > /home/w6sal/meshcoretomqtt/cron.log 2>&1

“Whoa, that’s a lot to unpack. What’s all this doing?”

Let’s break it down:

PATH=...: This line sets the PATH environment variable so cron knows where to find commands like Python and node. Cron runs in a very minimal environment, so we need to tell it where stuff lives. Important: Replace w6sal with YOUR actual username on the Pi.
@reboot: This is cron’s way of saying “run this when the system boots up.”
sleep 120: Wait 120 seconds (2 minutes) after boot before starting the script. Why? Because when a Raspberry Pi first boots, there’s a flurry of activity as services start up, the network comes online, and the system gets its bearings. If we try to start our MQTT bridge too early, it might not be able to connect to the MQTT broker yet, or the serial port might not be ready. Two minutes is usually enough time for everything to settle down.
/home/w6sal/meshcoretomqtt/venv/bin/python3: This is the full path to the Python interpreter in your virtual environment. We need the full path because cron doesn’t know about relative paths. Again, replace w6sal with your username.
/home/w6sal/meshcoretomqtt/mctomqtt.py: The full path to your MQTT bridge script. You get it by now—change w6sal to your username.
> /home/w6sal/meshcoretomqtt/cron.log 2>&1: This redirects all output (both standard output and errors) to a log file. This is SUPER useful for troubleshooting when things inevitably go wrong at 3 AM.

Save and exit the crontab editor (in nano, that’s Ctrl+X, then Y, then Enter).

Step 4B: Verifying Your Crontab

To make sure your crontab entry is correct, run:

crontab -l

This lists all your cron jobs. You should see the lines you just added.

Part 4: Testing and Verification (The “Does This Thing Actually Work?” Phase)

Before you reboot and hope for the best, let’s test things manually to make sure everything works.

Manual Test Run

Navigate to your bridge directory:
```
cd ~/meshcoretomqtt
```
Activate the virtual environment:
```
source venv/bin/activate
```
Run the bridge script manually:
```
python3 mctomqtt.py
```

If everything is working, you should see:

Messages about connecting to the MQTT broker
Data being read from the serial port
MQTT publish confirmations

If you see errors, now’s the time to fix them (check your MQTT broker settings, serial port permissions, etc.).

Press Ctrl+C to stop the script.

The Moment of Truth: Reboot Test

If the manual test worked, it’s time for the real test:

sudo reboot

Wait about 3 minutes (remember that 2-minute delay we added), then check if your bridge is running:

ps aux | grep mctomqtt.py

You should see your Python process running. If you don’t, check the log file:

cat ~/meshcoretomqtt/cron.log

This will show you any errors that occurred during startup.

Part 5: Troubleshooting (Because Murphy’s Law is Real)

Here are some common issues and their solutions:

Issue: Script doesn’t start on boot

Solution: Check your crontab paths. Make sure ALL paths use your actual username, not w6sal.
Solution: Verify the log file exists and check it for error messages.
Solution: Increase the sleep time from 120 to 180 seconds if your Pi is slow to boot.

Issue: Permission denied on serial port

Solution: Add your user to the dialout group:
```
sudo usermod -a -G dialout $USER
```
Then log out and back in (or reboot).

Issue: Can’t connect to MQTT broker

Solution: Verify your MQTT broker is running and accessible from the Pi.
Solution: Check your firewall settings.
Solution: Verify the MQTT broker address and port in your bridge configuration.

Issue: Data looks garbled or incomplete

Solution: Check your baud rate settings match between the firmware and the bridge script.
Solution: Try a different USB cable (yes, really).
Solution: Make sure you flashed the MQTT-specific firmware, not the standard firmware.

WooHoo: You Did It!

Congratulations! You now have a fully automated MeshCore MQTT bridge. Your mesh network data is flowing into your MQTT broker like electrons through a particularly well-organized wire. You can now:

Monitor your mesh network in real-time
Integrate MeshCore data with Home Assistant
Log everything to a database for later analysis
Build dashboards that make other hams jealous
Impress your friends with phrases like “MQTT bridge” and “serial-to-network gateway”

The best part? Once it’s set up, it just works. Your Raspberry Pi will faithfully start the bridge every time it boots, and your node will dutifully forward mesh data to MQTT. It’s the kind of “set it and forget it” solution that makes automation worth all the effort.

Now go forth and bridge those protocols! And when someone asks you how you get your mesh data into Home Assistant, you can smile knowingly and say, “Oh, I just run a little MQTT bridge on a Raspberry Pi.” Make it sound casual. They don’t need to know about the hours you spent figuring out crontab syntax.

Happy meshing!

73 from W6SAL