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File 03 · ELRS Receiver
An ExpressLRS receiver, open from antenna to firmware.
Four board designs, one firmware. Lite runs SX1281 on 2.4 GHz with a ceramic antenna. Lite-UFL swaps to a U.FL pigtail. Mono steps up to a single LR1121 for multi-band. Gemini runs dual LR1121 in ExpressLRS Xrossband mode for frequency-diverse links.
OSHWA certified · BE000033Model· pick your build
Coming soonSKU OPENRX-GEMINI
Teardown
- LR1121 · dual-band LoRa radio×2
- ESP32-C3 · Wi-Fi MCU×1
- RFX2401C · PA / LNA front-end×2
- SKY13373 · RF switch×2
- ELRS link antennas · U.FL×2
- Wi-Fi antenna (on-board ceramic)×1
- 32 MHz radio TCXO×1
- Solder pad I/O · CRSF UART×1
Published so you can study it. Produced so you don't have to.
In the box
- 1×OpenRX boardtier selected at checkout
- 1×CRSF servo cable3-pin JST-SH1.0, pre-crimped, 10 cm
- 1×Heat-shrink sleeve + double-sided tape
- 1×Build cardbatch ID, QC initials, ExpressLRS flash target, GitHub rev
- 2×U.FL dipole antennadiversity pair
Provenance
- DesignedLeuven, Belgium · schematic, PCB, BOM, firmware partnerships
- AssembledShenzhen, China · first runs, while we bring up an EU line
- NextEU assembly · in planning
Every spec, one table
- Firmware
- ExpressLRS (3.5.0+)
- Telemetry
- CRSF
- MCU
- ESP32-C3, 4 MB flash
- Wi-Fi antenna
- Dedicated on-board ceramic, separate from the link antenna
- Flashing
- UART with on-board BOOT button, Wi-Fi OTA, BF passthrough
- License
- CERN-OHL-S-2.0
- Radio
- 2× Semtech LR1121, two complete radio chains
- Flash target
- Unified_ESP32C3_LR1121_RX
- Telemetry power
- 12–22 dBm per radio (~158 mW), 12 dB RX LNA per chain
- Antenna
- 2× U.FL, one per radio
- Size
- 17.05 × 15.75 mm, 6-layer
Files you can fork, build on, or audit.
Straight from the repo. If a link 404s, the file moved; open an issue on the matching GitHub repo and we'll point it back.
Manufacturer
- Company
- Incutec BV
- Address
- Stapelhuisstraat 15, 3000 Leuven, Belgium
- contact@opendrone.be
