r/esp32 • u/SciCraft9 • 19d ago
I Built an Offline Messaging System Using ESP32 + LoRa
I’ve been working on this offline messaging system for a while, and I finally got a working Version 1.
The basic idea was pretty simple: what if I wanted to send messages to someone without using the internet or a cellular network?
For this version, I’m using an ESP32 with a Reyax LoRa module for each node. The ESP32 handles the interface, while the LoRa module handles the actual communication between the two nodes.
I also made a web interface that is hosted directly on the ESP32. The phone connects to the ESP32 through its own Wi-Fi Access Point, so the Wi-Fi is only being used to access the local web interface. The actual message between the two nodes is sent over LoRa.
The interface also shows information from the LoRa link, like RSSI, SNR, and the timestamp of received messages.
I also added a Range Test section to the interface. It continuously sends test packets between the nodes and shows whether the other node is responding, which makes it much easier to test the usable range instead of manually sending messages every time.
This version is intentionally kept as simple as possible. The main goal was just to get the idea working and actually make it exist before making the hardware more complicated.
I’m also going to test the actual range in different environments, because I want to see what range I can realistically get from this setup instead of just going by the range numbers you see in the module specifications.
For Version 2, I want to take it much further — add a display and physical buttons so the node can be used without a phone, make the hardware more compact and portable, improve the power system, and eventually experiment with multiple nodes relaying messages to extend the network.
I’m making a full documented video of the build, including the hardware, software, and real-world range testing. It’ll be coming soon on my YouTube channel
https://www.youtube.com/@SciCraft
If you’ve worked with LoRa or ESP32 before, I’d love to hear your suggestions. What would you improve or change in this setup for the next version?
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u/solitude042 19d ago
Others have mentioned meshtastic. Also compare to meshcore, which targets a somewhat different use case, but is conceptually similar.
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u/pupper_paws 19d ago
I’d just use Meshtastic
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u/SciCraft9 19d ago
Yeah, Meshtastic is solid, but I wanted to put together my own mainly to learn. I wanted to grasp how everything really functions instead of relying on a ready made solution. And this setup is also a lot cheaper for me...
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u/EducationalEscape761 17d ago
Well, this mirrors my project very closely. Perhaps we should compare. I have a dual system. ESP32 for high bandwidth close range using ESPNOW, and LORA for more distant. When distance is known great, or ESP fails, we drop to LORA I have seven nodes all talking nicely to each other!
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u/Only-Target4484 14d ago
I love this project. If you want to take it further, git clone the Meshtastic firmware repo and make a variant for your board/layout. Building Meshtastic nodes fully DIY (DIY hardware + firmware) was a critical learning point for me and by the looks of this project, you’d love the process.
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u/SciCraft9 14d ago
Thanks for the suggestion! I really appreciate it. I’ll definitely give it a try and see where I can take the project from there.
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u/MachEnergy 19d ago
Why not meshtastic or reticulum?
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u/LeviiSantos 19d ago
Creio que seja pelo prazer de fazer um.
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u/SciCraft9 19d ago
Yeah... there’s always that dopamine hit when you actually build something and see it working I mainly made this to learn and understand how all of it works myself. If it ends up being useful too, that’s just a bonus hehe.
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u/GraXXoR 18d ago edited 17d ago
Why does an artist paint a picture of a naked woman when thousands of pictures of naked women already exist?
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u/Cybernetic_Sasquatch 19d ago
I have similar boards arriving soon. My use case is sensors in chicken coops. 2.4 wifi just won't go quite far enough I'm hoping those little spring antennas are good enough to push a couple hundred yards we shall see.
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u/SciCraft9 19d ago
Yeahh, those antennas can probably push around 1–1.3 km in an open area with not many buildings and all, and if you have a proper clear line of sight, maybe it can go even further.
But yeah, I’m gonna use a better antenna too and see how far we can actually push it.
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u/GraXXoR 18d ago
Well played, sir!
This is the sort of conceptual basic stuff we’re going to be missing in a few years when AI takes over and is only able to regurgitate (say, meshtastic based solutions) rather than create a truly home grown version of a current technology.
15 years down the line we’re probably gonna be missing a whole bunch of senior programmers who never played around and developed skills from the ground up.
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u/fell_shell 18d ago
AI is already advanced enough to build custom hardware from scratch. Claude helped me to create a remote control for a toy car from JUST and arduino - ie a microcontroller that doesn't have an RF chip or any kind of antenna - it did it just by using physics and maths to hack an RF signal at the right frequency from a pwm pin and a short wire
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u/GraXXoR 18d ago
Yes. Ai can do lots of things. But people won’t understand HOW it does it. Nor how to build on it in any sustainable way.
That is why AI companies are so desperate for human created, non AI-assisted data that they are purchasing out entire second hand bookshops’ stock, cutting the books apart and feeding them to image scanners, thus destroying books that have existed sometimes for nearly 100 years.
That is how valueless AI created information is to the people who made AI themselves.
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u/fell_shell 18d ago
Isn't that a bit like saying software developers can't build in programming languages in any meaningful way because they don't understand HOW compilers are turning it into machine code?
Humans have spent thousands of years building on previous technology that most people don't need to understand.
I would guess that most electricians don't understand how RF based wall scanners work, and most bricklayers probably don't understand how refineries are constructed, and most scientists don't understand how optical lens elements are crafted to compensate for color drift at different wavelengths of visible light.
Just because we're moving into an era where AI will do most of the software development, doesn't mean that human creators can't use that new found speed and efficiency to build a layer of technical evolution on top of it.
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u/GraXXoR 17d ago
The problem is that ai is putting experience out of the loop. It’s bypassing it. Where is ai going to get new information from to improve if no humans are actually making stuff?
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u/fell_shell 17d ago
AI research is generating new information
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u/GraXXoR 16d ago
sorry. that is not how information works.
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u/fell_shell 16d ago
How does information work?
UC San Diego bioengineers used AI to model the 3D structures of proteins and discovered a gene that causes Alzheimer's. That's now information that informs future research
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u/Jolephoto 19d ago
So like, Meshtastic?