agessaman
c28548aecf
Five independent, behavior-preserving reductions. Measured on
Heltec_v3_repeater_observer_mqtt (non-PSRAM) and
ThinkNode_M7_repeater_observer_mqtt (PSRAM), 267/267 native tests green.
Drop the unused static-task bookkeeping. StaticTask_t _mqtt_task_tcb (344 B)
and StackType_t* _mqtt_task_stack were never used: there is no
xTaskCreateStatic call, the pointer was assigned nullptr immediately before
xTaskCreatePinnedToCore, and the two psram_free() calls on it were dead.
Size the wire-format scratch buffers from the protocol maximum. raw_hex[1024]
at three sites becomes 2*MAX_TRANS_UNIT+1, and raw_buf/reconstructed[512]
become MAX_TRANS_UNIT. Both writeTo() sites now check getRawLength() first:
writeTo() does not bounds-check and returns uint8_t, so the old 512-byte
buffers were the only thing absorbing a malformed payload_len, and the
post-hoc "raw_len > sizeof(buf)" test ran after the overrun.
Pass the already-known serialized length into publishToSlot() instead of
re-running strlen() per destination slot (up to 2 KB per packet per slot, and
NEIGHBORS_JSON_BUFFER_SIZE per neighbor snapshot). Same for the direct
publish in publishStatusToSlot().
Share one JSON buffer and one document across packet, raw, and status. All
publish paths serialize on the bridge task, so the separate status buffer and
document were never concurrent. Status keeps STATUS_JSON_BUFFER_SIZE as its
serialization ceiling, so which oversized status documents get dropped is
unchanged.
Route the document's pools through a PSRAM-preferring allocator. Under
ArduinoJson 7 StaticJsonDocument<N> is a deprecated empty subclass of
JsonDocument whose template argument only feeds capacity(); the object is
64 B and each pool block (4096 B here) came from plain malloc(), i.e. the
internal DRAM the mbedTLS working set needs. Mirrors NeighborsDocAllocator.
The old comment claiming an inline pool has been corrected.
Measured:
sizeof(MQTTBridge) non-PSRAM 13208 -> 12032 B (-1176, internal heap)
PSRAM 10492 -> 10080 B (-412, plus one fewer
768 B PSRAM allocation)
stack, non-PSRAM buildPacketJSON[FromRaw] 1264 -> 736 B
buildRawJSON 1136 -> 608 B
publishPacket 688 -> ~432 B
packetToHex 560 -> ~304 B
deepest publish chain ~2.6 -> ~1.8 KB of 8 KB
flash 1592513 -> 1592573 B (+60)
static RAM 74656 B unchanged -- MQTTBridge is heap-allocated, so
these savings are internal heap, not the linker figure
Deferred from the review: the QueuedPacket wire-only redesign (reward is
1.56 KB on non-PSRAM only, and Packet::readFrom() rejects payload_len == 0),
demand-driven slot clients/JWT tokens, and pool retention across publishes --
JsonDocument::to<T>() always calls clear(), which destroys pools, so
"retain pools by clearing the root object" needs a string-pool lifetime
analysis first.
About MeshCore
MeshCore is a lightweight, portable C++ library that enables multi-hop packet routing for embedded projects using LoRa and other packet radios. It is designed for developers who want to create resilient, decentralized communication networks that work without the internet.
🔍 What is MeshCore?
MeshCore now supports a range of LoRa devices, allowing for easy flashing without the need to compile firmware manually. Users can flash a pre-built binary using tools like Adafruit ESPTool and interact with the network through a serial console. MeshCore provides the ability to create wireless mesh networks, similar to Meshtastic and Reticulum but with a focus on lightweight multi-hop packet routing for embedded projects. Unlike Meshtastic, which is tailored for casual LoRa communication, or Reticulum, which offers advanced networking, MeshCore balances simplicity with scalability, making it ideal for custom embedded solutions, where devices (nodes) can communicate over long distances by relaying messages through intermediate nodes. This is especially useful in off-grid, emergency, or tactical situations where traditional communication infrastructure is unavailable.
MQTT Observer Setup — Prebuilt observer firmware, docs, and a changelog are at observer.gessaman.com. See the MQTT Implementation Guide for configuration, CLI commands, and troubleshooting.
⚡ Key Features
- Multi-Hop Packet Routing
- Devices can forward messages across multiple nodes, extending range beyond a single radio's reach.
- Supports up to a configurable number of hops to balance network efficiency and prevent excessive traffic.
- Nodes use fixed roles where "Companion" nodes are not repeating messages at all to prevent adverse routing paths from being used.
- Supports LoRa Radios – Works with Heltec, RAK Wireless, and other LoRa-based hardware.
- Decentralized & Resilient – No central server or internet required; the network is self-healing.
- Low Power Consumption – Ideal for battery-powered or solar-powered devices.
- Simple to Deploy – Pre-built example applications make it easy to get started.
🎯 What Can You Use MeshCore For?
- Off-Grid Communication: Stay connected even in remote areas.
- Emergency Response & Disaster Recovery: Set up instant networks where infrastructure is down.
- Outdoor Activities: Hiking, camping, and adventure racing communication.
- Tactical & Security Applications: Military, law enforcement, and private security use cases.
- IoT & Sensor Networks: Collect data from remote sensors and relay it back to a central location.
🚀 How to Get Started
- Watch the MeshCore QuickStart Playlist by The Comms Channel
- Watch the MeshCore Technical Presentation by Liam Cottle.
- Read through our Frequently Asked Questions and Documentation.
- Flash the MeshCore firmware on a supported device.
- Connect with a supported client.
For developers:
- Install PlatformIO in Visual Studio Code.
- Clone and open the MeshCore repository in Visual Studio Code.
- See the example applications you can modify and run:
- Companion Radio - For use with an external chat app, over BLE, USB or Wi-Fi.
- KISS Modem - Serial KISS protocol bridge for host applications. (protocol docs)
- Simple Repeater - Extends network coverage by relaying messages.
- Simple Room Server - A simple BBS server for shared Posts.
- Simple Secure Chat - Secure terminal based text communication between devices.
- Simple Sensor - Remote sensor node with telemetry and alerting.
The Simple Secure Chat example can be interacted with through the Serial Monitor in Visual Studio Code, or with a Serial USB Terminal on Android.
⚡️ MeshCore Flasher
We have prebuilt firmware ready to flash on supported devices.
- Launch https://meshcore.io/flasher
- Select a supported device
- Flash one of the firmware types:
- Companion, Repeater or Room Server
- Once flashing is complete, you can connect with one of the MeshCore clients below.
📱 MeshCore Clients
Companion Firmware
The companion firmware can be connected to via BLE, USB or Wi-Fi depending on the firmware type you flashed.
- Web: https://app.meshcore.nz
- Android: https://play.google.com/store/apps/details?id=com.liamcottle.meshcore.android
- iOS: https://apps.apple.com/us/app/meshcore/id6742354151?platform=iphone
- NodeJS: https://github.com/liamcottle/meshcore.js
- Python: https://github.com/fdlamotte/meshcore-cli
Repeater and Room Server Firmware
The repeater and room server firmware can be set up via USB in the web config tool.
They can also be managed via LoRa in the mobile app by using the Remote Management feature.
🛠 Hardware Compatibility
MeshCore is designed for devices listed in the MeshCore Flasher
📜 License
MeshCore is open-source software released under the MIT License. You are free to use, modify, and distribute it for personal and commercial projects.
Contributing
Please submit PR's using 'dev' as the base branch! For minor changes just submit your PR and we'll try to review it, but for anything more 'impactful' please open an Issue first and start a discussion. It is better to sound out what it is you want to achieve first, and try to come to a consensus on what the best approach is, especially when it impacts the structure or architecture of this codebase.
Here are some general principles you should try to adhere to:
- Keep it simple. Please, don't think like a high-level lang programmer. Think embedded, and keep code concise, without any unnecessary layers.
- No dynamic memory allocation, except during setup/begin functions.
- Use the same brace and indenting style that's in the core source modules. (A .clang-format is probably going to be added soon, but please do NOT retroactively re-format existing code. This just creates unnecessary diffs that make finding problems harder)
Help us prioritize! Please react with thumbs-up to issues/PRs you care about most. We look at reaction counts when planning work.
Running unit tests
To run unit tests, run the following command:
pio test --environment native --verbose
Road-Map / To-Do
There are a number of fairly major features in the pipeline, with no particular time-frames attached yet. In very rough chronological order:
- Companion radio: UI redesign
- Repeater + Room Server: add ACL's (like Sensor Node has)
- Standardise Bridge mode for repeaters
- Repeater/Bridge: Standardise the Transport Codes for zoning/filtering
- Core + Repeater: enhanced zero-hop neighbour discovery
- Core: round-trip manual path support
- Companion + Apps: support for multiple sub-meshes (and 'off-grid' client repeat mode)
- Core + Apps: support for LZW message compression
- Core: dynamic CR (Coding Rate) for weak vs strong hops
- Core: new framework for hosting multiple virtual nodes on one physical device
- V2 protocol spec: discussion and consensus around V2 packet protocol, including path hashes, new encryption specs, etc
📞 Get Support
- Report bugs and request features on the GitHub Issues page.
- Find additional guides and components on my site.
- Join MeshCore Discord to chat with the developers and get help from the community.