FigCNC is an open-source CNC controller board based on the ESP32 microcontroller, designed to run FluidNC firmware. It provides a compact and clean interface between the ESP32 and external stepper motor drivers, with optocoupler-isolated limit switch inputs, a tool-length probe input, onboard microSD storage for G-code files, and a pendant UART interface — all powered directly from the machine's 12–36 V supply rail.
FigCNC includes an RS485 interface (MAX3485 transceiver) for direct Modbus RTU control of Huanyang-compatible VFD spindles, making it suitable for machines that require closed-loop spindle speed management.
- Features
- Board Overview
- Electrical Specifications
- PCB Layout
- Manufacturing
- GPIO Pin Reference
- Connectors
- FluidNC Configuration
- Provided Configuration Files
- Pendant
- License
- FluidNC native — drop-in
config.yamlconfigurations are provided for each axis and spindle combination. No firmware modifications required. - Wide input voltage — 12 V to 36 V DC, regulated onboard to 5 V via the TPS5430DDA synchronous buck converter.
- Four stepper channels — X, Y1, Y2, and Z step/direction outputs on a single 12-pin Phoenix-style screw terminal. The second Y channel enables dual-motor gantry operation with independent homing.
- Isolated limit switch inputs — all four limit switch inputs and the probe input pass through LTV-817 optocouplers, keeping high-voltage switch wiring isolated from the ESP32.
- Tool-length probe — dedicated probe input (active-low) with optocoupler isolation.
- MicroSD card — SPI-connected microSD socket for storing G-code files. Accessible via the FluidNC web interface or over the serial connection.
- Pendant interface — UART2 exposed on a JST-XH connector for connecting a wired or wireless pendant.
- UART / FTDI header — a 4-pin header (RX, TX, GND, 5 V) provides direct serial access for firmware flashing and debug.
- RS485 VFD spindle control — a MAX3485 half-duplex RS485 transceiver and a dedicated 3-pin screw terminal for direct Modbus RTU control of Huanyang-compatible VFDs, eliminating the need for a PWM-to-analog converter.
- Compact form factor — four M3 mounting holes, compatible with standard DIN rail brackets and CNC controller enclosures.
| Parameter | Value |
|---|---|
| Input voltage | 12–36 V DC |
| Input connector | 2.1 mm barrel jack |
| Onboard regulated output | 5 V (TPS5430DDA, up to 3 A) |
| Microcontroller | Espressif ESP32-DEVKITC-32E |
| Stepper interface | Step/Direction (StepStick-compatible signal levels) |
| Step pulse width | 10 µs (configurable in FluidNC) |
| Direction setup delay | 6 µs |
| Motor idle timeout | 250 ms |
| Limit / probe isolation | LTV-817 optocoupler (×5) |
| RS485 transceiver | Maxim MAX3485, 120 Ω termination fitted |
| MicroSD interface | SPI Mode @ 8Mhz |
| Front copper | Back copper |
|---|---|
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The full schematic is also available as a PDF.
All files required for PCB fabrication and assembly are included in each board's subdirectory.
| File type | Location |
|---|---|
| Gerber files (fabrication) | FigCNC-Pro/gerbers/ |
| Drill files (.drl) | Included in gerbers directory |
| Bill of materials (CSV) | FigCNC-Pro/FigCNC-Pro-BOM.csv |
| Pick-and-place positions | FigCNC-Pro/FigCNC-Pro-positions.csv |
| Schematic (PDF / SVG) | FigCNC-Pro/schematic/ |
The Gerber files have been validated for standard 2-layer PCB fabrication. The board can be ordered from any standard PCB manufacturer (e.g. JLCPCB, PCBWay, OSH Park) using the provided files without modification.
All GPIO assignments below correspond to the provided config.yaml files and the board's fixed routing. They should not be changed unless the PCB is modified.
| Signal | ESP32 GPIO |
|---|---|
| X — Step | 22 |
| X — Direction | 13 |
| X — Limit (positive) | 32 |
| Y1 — Step | 14 |
| Y1 — Direction | 27 |
| Y1 — Limit (positive) | 35 |
| Y2 — Step (dual-Y only) | 26 |
| Y2 — Limit (positive, dual-Y only) | 34 |
| Z — Step | 25 |
| Z — Direction | 33 |
| Z — Limit (positive) | 39 |
| Probe (active-low) | 36 |
| SPI MISO | 19 |
| SPI MOSI | 23 |
| SPI SCK | 18 |
| MicroSD CS | 5 |
| UART1 TX — VFD RS485 | 15 |
| UART1 RX — VFD RS485 | 4 |
| UART1 RTS — VFD RS485 | 21 |
| UART2 TX — Pendant | 17 |
| UART2 RX — Pendant | 16 |
This is the primary stepper output terminal. Connect each signal to the corresponding input of your external stepper drivers (e.g. TB6600, DM542, or similar).
| Pin | Signal | Notes |
|---|---|---|
| 1 | X-LIM | X-axis limit switch (optocoupler input) |
| 2 | Y1-LIM | Y1 limit switch (optocoupler input) |
| 3 | Y2-LIM | Y2 limit switch (optocoupler input, dual-Y only) |
| 4 | Z-LIM | Z-axis limit switch (optocoupler input) |
| 5 | Z-DIR | Z direction output |
| 6 | Z-STP | Z step output |
| 7 | Y2-DIR | Y2 direction output (dual-Y only) |
| 8 | Y2-STP | Y2 step output (dual-Y only) |
| 9 | Y1-DIR | Y1 direction output |
| 10 | Y1-STP | Y1 step output |
| 11 | X-DIR | X direction output |
| 12 | X-STP | X step output |
Connect to the RS485 terminals of a Huanyang-compatible VFD. A 120 Ω termination resistor is fitted on the board.
| Pin | Signal |
|---|---|
| 1 | A (+) |
| 2 | B (−) |
| 3 | GND |
| Pin | Signal |
|---|---|
| 1 | 5 V |
| 2 | GND |
| 3 | RX (from pendant) |
| 4 | TX (to pendant) |
| Pin | Signal |
|---|---|
| 1 | RX |
| 2 | TX |
| 3 | GND |
| 4 | 5 V |
The probe input is located on the left-side screw terminal block (J1). Connect the probe to the designated probe pin and GND. The input is active-low and optocoupler-isolated.
FigCNC runs FluidNC, an ESP32-based CNC firmware compatible with G-code senders such as FluidDial, CNCjs, UGS, and Candle.
Configuration is done via a single config.yaml file stored on the ESP32 (uploaded via the FluidNC web interface or over serial). Ready-to-use configuration files are provided for each supported machine topology.
These values match the provided configurations and serve as a reference starting point. You must adjust steps_per_mm, max_rate_mm_per_min, acceleration_mm_per_sec2, and max_travel_mm in the config file to match your specific machine geometry, lead screw pitch, microstepping settings, and motors before running the machine.
| Axis | Steps/mm | Max rate (mm/min) | Acceleration (mm/s²) | Max travel (mm) |
|---|---|---|---|---|
| X | 320 | 2500 | 100 | 327 |
| Y | 400 | 3000 | 100 | 327 |
| Z | 320 | 1600 | 100 | 95 |
| Parameter | Value |
|---|---|
| Protocol | Huanyang Modbus RTU |
| Baud rate | 9600 |
| Modbus ID | 1 |
| Speed map | 0–25% → 0 RPM, 25–100% → 6000–24000 RPM |
Pre-built config.yaml files are included for the following machine topologies. Upload the appropriate file to the ESP32 using the FluidNC web interface or over serial before running the machine.
| Configuration | Path |
|---|---|
| Single Y-axis, no VFD | FigCNC-Pro/configs/single-y-axis-no-vfd/config.yaml |
| Single Y-axis, with Huanyang VFD | FigCNC-Pro/configs/single-y-axis-with-vfd/config.yaml |
| Dual Y-axis, no VFD | FigCNC-Pro/configs/double-y-axis-no-vfd/config.yaml |
| Dual Y-axis, with Huanyang VFD | FigCNC-Pro/configs/double-y-axis-with-vfd/config.yaml |
FigCNC is designed to work with a 3D-printable pendant enclosure for the FluidDial CNC pendant, built around the Cheap Yellow Display (CYD / ESP32-2432S028R). The enclosure files, assembly instructions, and wiring reference are included in this repository.
See the FigCNC Pendant README for full details.
This project is licensed under the CERN Open Hardware Licence v2 - Permissive (CERN-OHL-P v2). You are free to use, modify, and manufacture the hardware for personal and commercial purposes, with or without releasing your modifications, provided attribution is maintained.
See LICENSE for full terms. This project is not affiliated with FluidNC or FluidDial — it is simply designed to run their firmware.
Caution
This hardware is provided as-is. Use at your own risk. The developer accepts no responsibility for any damage to equipment, property, or injury arising from the use, assembly, or operation of this project.
Designed by FIGAMORE.