OpenESC-30x30
Open-source 4-in-1 BLDC ESC with a 30.5 × 30.5 mm mounting pattern, built around four independent AT32F421 motor controllers running AM32. Six-layer, DShot over the standard 8-pin connector. Designed in KiCad for JLCPCB assembly.
Part of the incutec OpenDrone line (incutec-hw/OpenESC-30x30).
A smaller OpenESC_20X20 (20×20 mm) shares this design and mirrors this repo. The two differ only in board/mounting size and a few power-stage parts.
Architecture
Four fully independent ESC channels share a common power input and telemetry connector. Each channel has its own MCU and gate driver; the high-current stage is six MOSFETs per channel (three half-bridges). This is the distributed-MCU AM32 4-in-1 topology rather than a single-MCU design. Values below are extracted from the KiCad design files (hardware/4in1.kicad_sch, hardware/ESC.kicad_sch, hardware/4in1.kicad_pcb) and the production BOM (hardware/production/Rev1-30x30_bom.csv).
| Block | Part | LCSC | Per board |
|---|---|---|---|
| Motor MCU | AT32F421G8U7 (QFN-28) | C2765098 | 4 |
| Gate driver | NSG2065Q (QFN-24) | C41414478 | 4 |
| Power MOSFETs | SP40N01GHNK PDFN-8L (5×6) | C22385416 | 24 (6 per channel) |
Specifications
| Parameter | Value |
|---|---|
| Channels | 4 independent BLDC channels |
| MCU | AT32F421G8U7 (ARM Cortex-M4, QFN-28), one per channel |
| Gate driver | NSG2065Q (QFN-24, FD6288Q-compatible), one per channel |
| Power MOSFETs | SP40N01GHNK, N-channel, PDFN-8L (5×6), 24 total (XRS280N03C selected as drop-in next-gen — not yet swapped) |
| Current sense | Board-level high-side: INA186A3IDCKR (100 V/V, SC-70-6) across 2× 0.2 mΩ 2512 shunts in parallel (0.1 mΩ) in the +BATT feed → 10 mV/A → ~330 A full-scale at 3.3 V ADC |
| Input | +BATT direct from connector/pads, 3S–6S |
| Input protection | 3× SMBJ24A TVS (24 V standoff) |
| Buck regulator | LMR54406DBVR (SOT-23-6) + FTC160808S4R7MBCA 4.7 µH inductor → +10 V gate-drive rail (FB 115k/10k, Vref 0.8 V → 10.0 V) |
| LDO | TLV76733DRVR (WSON-6) → +3V3 (MCUs, sensing), from +10 V |
| Signal protocol | DShot (4 independent signal lines, one per channel) |
| Firmware | AM32 (per-channel AT32F421 target, flashed individually) |
| PCB | 6-layer, 1.69 mm |
| Mounting pattern | 30.5 × 30.5 mm, 4× Ø4.0 mm holes (M3) |
Current/voltage ratings are not printed on the design files. The input clamp is set by the SMBJ24A TVS (24 V standoff → 3S–6S); the MOSFET (SP40N01GHNK) and current-sense full-scale (~330 A) set the practical envelope. Characterize before quoting a hard rating.
Connector
8-pin JST SM08B-SRSS-TB (J1). Pin-to-net mapping extracted from the schematic (net labels at the connector pins):
| Pin | Net | Function |
|---|---|---|
| 1 | +BATT | Battery positive |
| 2 | GND | Ground |
| 3 | /CURR | Current-sense telemetry (INA186 output) |
| 4 | (unconnected) | No dedicated telemetry pin — telemetry handled by extended DShot |
| 5 | /M1 | DShot signal, channel 1 |
| 6 | /M2 | DShot signal, channel 2 |
| 7 | /M3 | DShot signal, channel 3 |
| 8 | /M4 | DShot signal, channel 4 |
Connector ground returns on the shield/mounting pads P1/P2 (both GND). The same eight signals are also broken out as direct solder pads (U3). Pin 4 — the dedicated telemetry pin on the Betaflight 8-pin standard — is intentionally unconnected: ESC→FC telemetry is carried over the motor signal lines via the bidirectional extended DShot protocol.
Variants and revisions
| File | Description |
|---|---|
hardware/4in1.kicad_pro / .kicad_pcb / .kicad_sch |
Main design (30×30). |
hardware/4in1-panel.kicad_pro / .kicad_pcb |
Panelized version for production fabrication. |
This repo is the 30×30 member of the OpenESC family; the 20×20 sibling lives in OpenESC_20X20. Production exports in hardware/production/ are versioned V0.1–V0.4 and Rev1. Rev1-30x30 is the 30×30-only fabrication set; Rev1-30x3020x20 is a combined shared-fab set produced alongside the mini.
Firmware
AM32 — incutec's default ESC firmware. Boards ship with the AM32 bootloader pre-loaded; firmware is flashed and configured in-browser at am32.ca. Each channel's AT32F421G8U7 is an independent AM32 target. The AT32F421 + NSG2065Q per-channel topology and the DShot signal nets are the standard AM32 4-in-1 hardware target. Works with Betaflight and other DShot-capable flight controllers.
Repository structure
README.md LICENSE CLAUDE.md Repo root: docs + license + agent instructions
images/ Board render images
licensing/ Hardware license, third-party notices, trademark policy
hardware/ KiCad 9 project (everything to build/fab the board)
├── 4in1.kicad_sch Top schematic (power, current sense, connector)
├── ESC.kicad_sch Single ESC channel sheet (instantiated 4×)
├── 4in1.kicad_pcb Main board layout (6-layer)
├── 4in1.kicad_pro Main project
├── 4in1-panel.kicad_pcb / .kicad_pro Panelized layout/project for production
├── components.kicad_sym Project-local symbol library
├── 4in1ESC-30x30.pretty/ Project-local footprints
├── 4in1ESC-30x30.3dshapes/ 3D models (STEP)
├── fp-lib-table / sym-lib-table Project-local library tables (${KIPRJMOD})
├── 4in1.step / 4in1.glb Exported board 3D models
├── production/ JLCPCB fabrication exports (gerbers, BOM, CPL) per revision
├── fabrication-toolkit-options.json KiCad Fabrication Toolkit settings
├── cost-analysis.md JLCPCB 500-unit cost breakdown (predates latest BOM)
└── database/ Component analysis notes
License
Hardware: CERN-OHL-S-2.0. See LICENSE, licensing/THIRD_PARTY.md, and licensing/TRADEMARKS.md. Some bundled 3D model assets carry their own upstream notices (CC-BY-SA-4.0 / GPL).