An all-in-one board for toothpick-class 6S FPV: flight controller, 4-in-1 ESC and ExpressLRS receiver on a single 25.5 x 25.5 mm board. One board, one connector, no stack. It merges three boards OpenDrone already makes.
Nobody holds this board yet: claim it on Discord.
The three-board stack works and OpenDrone already ships all three parts, but on a toothpick the stack is most of the weight and all of the height. Merging them removes two connectors, two sets of mounting hardware and a lot of wiring, and those connectors are where builds fail.
The parts are proven separately, so this is an integration problem rather than a research one. That makes it a good first board for someone who has not designed for us before. The only 6S AIO with onboard serial ELRS on the market is closed and digital-only; an open one with analog OSD and blackbox has a place, see the market research below.
Targets. The board does not exist yet.
| Mounting | 25.5 x 25.5 mm |
| Input | 6S |
| Flight controller | RP2354A, Betaflight target |
| ESC | 4x AM32, one MCU per channel like the OpenESC boards |
| Receiver | ExpressLRS 2.4 GHz, ESP32-C3 + SX1281 |
| Assembly | JLCPCB, LCSC basic parts preferred |
- 25.5 x 25.5 mm mounting, the toothpick standard.
- Runs stock firmware: Betaflight on the FC, AM32 per ESC channel, ExpressLRS on the receiver. No forks.
- Reuses the manufactured circuits of OpenFC-Lite-Mini, OpenESC-20x20 and OpenRX where they fit; parts come from the shared library first.
- JLCPCB assembly from LCSC parts, extended parts kept to a minimum.
- Do not start from the three schematics stitched together. That was tried,
and it produced a board that looked finished and was not (recoverable at the
pre-reset-2026-08-13tag). Start from the requirements.
The three designs this merges, all manufactured and flying:
- OpenFC-Lite-Mini: the RP2354A flight controller
- OpenESC-20x20: the AM32 4-in-1 power stage
- OpenRX: the ELRS receiver
Research so far, reference rather than decisions:
- research/MARKET-RESEARCH-2026-06.md: competing toothpick and whoop AIOs, June 2026
- research/ALTERNATIVES.md: ESC-stage part alternatives, gate driver and FET options, March 2026
- The stitched design reset in August 2026 is in the git history before #9; reference for the thinking, not a design to continue from.
The decisions to make before any of it gets drawn. Answering them is a real contribution that needs no KiCad.
- Thermal. Four power stages next to an MCU and a radio on 25.5 mm square, with no airflow guarantee. What is the continuous current budget, and does it need copper beyond 2 oz outer?
- RF isolation. A 2.4 GHz receiver on top of four switching power stages. Where does the antenna go, what does the ground plane have to do, and is a shield can needed?
- Current sensing. Board level like the ESCs, or per channel?
- Video. Analog OSD, digital only, or both?
- What gets dropped. An AIO cannot carry everything the three separate boards do. Which I/O is worth the space?
What pairs with what, and what is available: opendrone.be.
KiCad files cannot be merged, so say what you intend to change before you do, on Discord. How everything works: CONTRIBUTING.md.
Hardware licensed under CERN-OHL-S-2.0, see LICENSE.