OpenRX
Open-source ExpressLRS (ELRS) receiver line for FPV/RC, part of the incutec OpenDrone line. Four board variants share an Espressif ESP32-C3 core, a TLV75533 3.3 V LDO, and the ExpressLRS unified firmware; they differ in radio IC, frequency band, RF front-end, and ELRS antenna. All four are 6-layer boards designed in KiCad 10 for JLCPCB assembly. Family design detail: DESIGN.md. Per-variant notes: OpenRX-<variant>/DESIGN.md.
| Lite | Lite-UFL | Mono | Gemini |
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| SX1281, 2.4 GHz, chip antenna | SX1281, 2.4 GHz, U.FL | LR1121, dual-band, U.FL | 2x LR1121, dual-radio, 2x U.FL |
Status
Hardware validated, 2026-08-05, all four variants (Lite, Lite-UFL, Mono, Gemini), on the combined OpenRX-all build ordered 2026-06-10.
The only fabricated set is that 2026-06-10 OpenRX-all order, tracked in OpenRX-Gemini/fab/ and OpenRX-Gemini/export/. The four per-variant layouts have since diverged from it: commit 5cd885c (2026-08-05) reworked the clock 3.3 V supply, enlarged pads, and grew the Lite, Lite-UFL and Mono outlines by 1.0 mm. Those changes have not been fabricated, and OpenRX-Gemini/fab/ has not been re-panelised from them.
Certification
All four variants are certified open source hardware by the Open Source Hardware Association. Each board carries its own OSHWA UID:
| Variant | OSHWA UID |
|---|---|
| Lite | BE000030 |
| Lite-UFL | BE000031 |
| Mono | BE000032 |
| Gemini | BE000033 |
Build video: How LoRa (ExpressLRS) Drone Receivers Work
Links
- Product page: opendrone.be/products/openrx
- Video channel: JustFPV on YouTube
Specifications
| Parameter | Lite | Lite-UFL | Mono | Gemini |
|---|---|---|---|---|
| Radio IC | Semtech SX1281 | Semtech SX1281 | Semtech LR1121 | 2x Semtech LR1121 |
| Band | 2.4 GHz | 2.4 GHz | Sub-GHz + 2.4 GHz | Sub-GHz + 2.4 GHz, dual-radio (Xrossband) |
| ELRS antenna | Chip antenna (AE2) | U.FL (J1) | U.FL (J1) | 2x U.FL (J1, J2) |
| RF front-end | Band-pass filter | Band-pass filter | PA/LNA + RF switch + balun + BPF | 2x (PA/LNA + RF switch + balun + BPF) |
| Max TX power | 13 dBm | 13 dBm | 12-22 dBm | 12-22 dBm per radio |
| Board size | 10.0 x 11.5 mm | 10.0 x 11.5 mm | 10.0 x 17.3 mm | 17.0 x 15.7 mm |
| PCB | 6-layer, 1.0 mm | 6-layer, 1.0 mm | 6-layer, 1.0 mm | 6-layer, 1.0 mm |
Common to all variants: ESP32-C3 MCU, 5 V pad input, CRSF over UART0, WS2812B status LED, dedicated 2.4 GHz Wi-Fi chip antenna for OTA. Part-level detail (LDO, clocks, RF chains, pads, pin maps, firmware targets) is in DESIGN.md.
Repository layout
| Path | Contents |
|---|---|
OpenRX-Lite/ |
KiCad 10 project: SX1281 2.4 GHz, on-board chip antenna |
OpenRX-Lite-UFL/ |
KiCad 10 project: SX1281 2.4 GHz, U.FL |
OpenRX-Mono/ |
KiCad 10 project: single LR1121 dual-band, U.FL |
OpenRX-Gemini/ |
KiCad 10 project: dual LR1121, 2x U.FL; also the combined OpenRX-all board with its fab/ gerber set |
shared/libs/ |
OpenRX-Shared symbol/footprint/3D library (in-repo) |
shared/sheets/ |
Shared hierarchical sheet (RX core, legacy) |
shared/elrs-targets/ |
ExpressLRS hardware-target JSON + targets_entries.json |
libs/KiCad-Library |
Shared Incutec symbol/footprint/3D library (git submodule) |
images/ |
Board renders (all variants) and certification marks |
exports/schematics/ |
Schematic PDFs, one per variant |
verification/ |
BOM and design-verification scripts |
archive/legacy-projects/ |
Retired designs (Nano, 900, PWM, Dual) |
DESIGN.md |
Family design notes |
Each variant directory holds the KiCad project (.kicad_pro/.kicad_sch/.kicad_pcb), a DESIGN.md, and an export/ with BOM or STEP output; OpenRX-Gemini/fab/ additionally holds the ordered gerber/drill set. Board renders live only in the root images/, one set for all four variants.
Design entry points
- Lite / Lite-UFL:
OpenRX-Lite/OpenRX-Lite.kicad_schandOpenRX-Lite-UFL/OpenRX-Lite-UFL.kicad_sch(top) ->esp32c3_sx1281_lite.kicad_sch(ESP32-C3 + SX1281 + LDO + RGB LED) - Mono:
OpenRX-Mono/OpenRX-Mono.kicad_sch(top) ->esp32c3_lr1121_mono.kicad_sch - Gemini:
OpenRX-Gemini/OpenRX-Gemini.kicad_sch(top) ->esp32-c3.kicad_sch+clock.kicad_sch+lr1121.kicad_sch(instantiated twice) - Board layouts:
OpenRX-<variant>/OpenRX-<variant>.kicad_pcb, 6 copper layers; combined production boardOpenRX-Gemini/OpenRX-all.kicad_pcb
Clone with --recursive so the libs/KiCad-Library submodule is present. Library layout and symbol/footprint sourcing: the Libraries section of DESIGN.md.
Build and export
git clone --recursive https://github.com/OpenDrone-hw/OpenRX.git
Open a variant's .kicad_pro in KiCad 10. Production exports (gerbers, BOM, CPL) are generated with the KiCad Fabrication Toolkit plugin, using the tracked per-variant fabrication-toolkit-options.json. Headless checks and exports use kicad-cli:
kicad-cli sch erc --exit-code-violations OpenRX-Lite/OpenRX-Lite.kicad_sch
kicad-cli pcb drc --exit-code-violations OpenRX-Lite/OpenRX-Lite.kicad_pcb
kicad-cli pcb export gerbers -o out/ OpenRX-Lite/OpenRX-Lite.kicad_pcb
Manufacturing
Fabricated and assembled at JLCPCB: 6-layer, 1.0 mm boards, LCSC parts. The validated build was ordered as the combined OpenRX-all board (all four variants on one PCB): gerbers in OpenRX-Gemini/fab/, BOM and placement in OpenRX-Gemini/export/. That set is historical, see Status; re-export from the current per-variant boards before ordering. Revision history: the Revisions section of DESIGN.md.
Contributing
See CONTRIBUTING.md.
License
Hardware licensed under CERN-OHL-S-2.0. See LICENSE.