FLRNode

The encrypted radio link for makers: $12 a node, up to 1 Mbps and 2 km, no license.

README en español

Why

Off-grid options today force a trade-off:

	Range	Bandwidth
LoRa 868/915	several km 🟢	0.3-20 kbps 🔴
WiFi	30-100 m 🔴	100+ Mbps 🟢

FLRNode fills the gap in the middle: hundreds of meters to 2 km, at up to 1 Mbps, encrypted, legal in the EU (and anywhere 2.4 GHz ISM is).

It does this with two transports on one firmware:

• ESP-NOW tier ($0 extra): the ESP32 (or even a $5 ESP8266) already in your drawer. ~100-300 m, millisecond latency.
• FLRC tier (one $5 module): Semtech SX1280's almost-forgotten Fast Long Range Communication mode, FSK with turbo FEC designed for drone racing. 260/520/1040 kbps, 0.5-2 km. Almost nobody uses it. We do.

On top of that link runs Reticulum, a cryptography-first mesh networking stack, so you get end-to-end encrypted messaging, file transfer and more, out of the box, with zero configuration.

Quick start

Two WEMOS D1 minis, two hosts (or one host + one Raspberry Pi):

git clone https://github.com/juanmicl/flrnode && cd flrnode
sh scripts/install.sh            # installs flrn (host CLI) + rns, runs flrn setup

Flash both bridges — EACH with the OTHER's MAC as its peer (each boot line prints the MAC you need; exact per-board commands in TEST-CHECKLIST.md):

pio run -e d1_mini_bridge -t upload

Then:

flrn scan                                   # find bridges: fw, mode, channel, MAC
flrn stats /dev/ttyUSB0                     # live ARQ counters (--watch to poll)
flrn config set channel 6 --all-bridges     # apply + persist on both bridges
flrn test /dev/ttyUSB0 /dev/ttyUSB1         # over-air link test + verdict
flrn doctor                                 # health checks with fixes

Requires: a FLRNode bridge on USB (CH340), Python 3.10+, and rnsd running on each host (docs/host-setup.md). (M5: the one-line curl -sSL flrnode.sh | sh installer — today, run the script from a checkout.)

Status

M1 (ESP-NOW transport) and M2 (Reticulum bridge) are closed with bench-verified results. M3 (flrn CLI, this quick start) is code-complete with a headless integration suite; M4 brings the FLRC tier and published benchmarks.

Known limitation today: each bridge pairs with one peer — links are point-to-point until multi-peer support lands with M4/M5.

Supported hardware

Board	Cost	Transports	Notes
WEMOS D1 mini (ESP8266)	~$5	ESP-NOW	the cheapest encrypted radio link you can build
Any ESP32 DevKit	~$7	ESP-NOW (+LR mode)	best zero-extra-hardware range
LilyGO T3S3 (SX1280)	~$25	ESP-NOW + FLRC	all-in-one, OLED, battery
ESP32 + bare SX1280 module	~$12	ESP-NOW + FLRC	DIY wiring: SPI + BUSY + DIO1

What you build with it

• 🔐 Off-grid encrypted comms: Sideband / MeshChat / NomadNet over radio
• 🔌 Transparent serial pipe: replace a cable across a farm, venue or building
• 📡 High-speed mesh backbone: link Reticulum nodes that are too close for LoRa's patience and too far for WiFi's legs
• 🤖 Robot/drone telemetry: FLRC was designed for this. ms latency, FEC, 1 Mbps (roadmap)

How it works

[Host A]                                [Host B]
  rnsd ── SerialInterface (HDLC)          rnsd
    │ USB serial @ 921600                  ▲
    ▼                                       │
┌─────────────────────────────┐   ┌────────┴──────────┐
│ FLRNode firmware            │   │ FLRNode firmware  │
│  ┌─────────┐  ┌──────────┐  │   │                   │
│  │ HDLC    │◄─┤ Transport│◄─┼───┼─► radio ──────────┤
│  │ framer  │  │ ESP-NOW  │  │ 2.4 GHz ISM          │
│  │ + frag. │  │ or FLRC  │  │   └───────────────────┘
│  └─────────┘  └──────────┘  │
│  LBT CSMA · stats · config  │
└─────────────────────────────┘

The core is transport-agnostic: one framing layer, two radio backends, more to come.

Benchmarks: measured, not marketing

We will publish real numbers from real hardware, for every rate and distance, in docs/benchmarks.md as the hardware milestones complete. No simulated numbers, ever.

Radio & legal compliance

• 2.4 GHz ISM band (2400-2483.5 MHz), ≤ 20 dBm EIRP including antenna per ETSI EN 300 328
• Listen-before-talk CSMA always on (adaptive equipment)
• Firmware refuses configurations that would exceed EIRP limits
• Default channel 2440 MHz (clear of busy WiFi edges)
• Full compliance notes will live in docs/compliance.md

FLRNode is legal to operate without a license across the EU and in any region with a 2.4 GHz ISM band. Always check your local rules.

Roadmap

• M1: ESP-NOW transport, two-node link
• M2: Reticulum integration (Sideband/MeshChat work)
• M3: flrn CLI + one-line host installer
• M4: FLRC transport (SX1280) + published benchmarks
• M5: Web flasher + v1.0 launch
• Meshtastic 2.4 GHz interop bridge
• ESP8266 mini-node preset ($5 end-to-end)

Comparison

	FLRNode	Meshtastic	RNode
Bandwidth	260k-1 Mbps	0.3-20 kbps	0.3-50 kbps
Range (typ.)	0.1-2 km	1-10 km	1-10 km
E2E encryption	✅ (Reticulum)	app-level	✅
Mesh	✅ multi-hop	✅	✅
Cheapest node	$5	$20	$30
Works with	Reticulum apps	Meshtastic apps	Reticulum apps

We're friends with all of these. Meshtastic and RNode are your pick for maximum range; FLRNode is your pick when you need megabits.

Contributing

Issues, PRs, board definitions, benchmarks and translations welcome.

Credits

• Mark Qvist: Reticulum, LXMF, RNode (the reason any of this works)
• jgromes: RadioLib
• The Meshtastic community, for proving 2.4 GHz mesh is wanted

License

MIT. See LICENSE.