Pin Definition Overview

The ports of FluidNC can all be freely defined and allocated through the Yaml file, so there is no fixed PinMap.

Our current definition is based on the test Yaml we use.

When applying it to your machine, you will need to define the pins yourself.

Key to the circled numbers

If you find the following section challenging, don't worry. You can complete the checklist steps first and then come back - it will make much more sense.

①
  • GPIO2 as Input: Requires :pu configuration in YAML file.
  • GPIO.26 as Input: Requires jumper selection first.
  • Hardware Note: Both IOs are connected to MCU via optocouplers with fixed 5V supply.
②
  • Compatible Input Types: Standard ON/OFF input, 5V signal switch, or industrial 12V/24V PNP/NPN switches.For safety reasons, please connect a resistor of 2.2kΩ or higher in series with the signal terminal when using a 24V supply（the version after 2026 july no need）.
  • Default Jumper (5V): Suitable for standard input and 5V signal input.
  • SW-VCC Selection: Set to Vmot-main. Your industrial switch voltage must match Vmot-main.
  • NPN/PNP Trigger Mode: Configure in YAML by adding or removing the :low parameter.
③
  • Output Capability: Can output 5V PWM signals or 5V switching signals for controlling spindles, lasers, servos, etc.
  • Circuit Requirement: Requires connection with any GND on the board to form a complete circuit.
  • GPIO Linkage: GPIO.4 and GPIO.12 are interconnected with the MOSFET on the orange terminal.
  • MOSFET Output: The MOSFETs can output voltage equal to Vmot-main or turn off the circuit, and are used to drive inductive loads such as solenoid valves. There are two output channels, controlled by GPIO.4 and GPIO.12 respectively.
④
  • RS485 Interface: This is an RS485 output interface.
  • A/B Polarity: If A and B are reversed, simply swap them. Reversed connections will not cause device damage.
  • Configuration Reference: Related settings can be configured by referring to the test code examples.
⑤
  • Analog Output: Provides 0-10V analog output for frequency converters. Connect GPIO.13 and GND, then configure to obtain the corresponding voltage.
  • Optocoupler Switches: OPT-IO.14/OPT-COMMON and OPT-IO.15/OPT-COMMON form switch pairs (both ends of optocouplers).
  • Digital Control: Controlled via IO.14 and IO.15 to open/close circuits, usable as standard digital outputs to signal frequency converters.
  • Start/Stop Function: For frequency converters requiring start/stop control, configure the onboard relay's NO (Normally Open) or NC (Normally Closed) contacts as control signals.
⑥
  • Function: This variable resistor is used to adjust the maximum voltage of the 10V output.
  • Calibration Scenario: When using maximum output commands (e.g., M3 S24000), if the output voltage does not reach 10V.
  • Adjustment Method: Fine-tune this variable resistor until the output voltage reaches exactly 10V.
⑦
  • SW-VCC Function: Used to select the voltage for switch inputs, corresponding to the description in Point ② above.
⑧
  • Control Source: Relay output is controlled by GPIO.26.
  • Configuration: Must select "Relay Output" in the GPIO.26 function selection jumper.
  • Application: The relay can operate as a standalone output or provide switching signals to other devices.
⑨
  • Output Capability: Can output the same voltage as Vmot-main or off. used to drive inductive loads such as solenoid valves.
  • Control Principle: Controlled via IO.12 or IO.4 by switching GND connection to complete the circuit.
  • Voltage Note: Vmot-main is positive voltage, while IO.12-MOS-GND and IO.4-MOS-GND ports serve as GND.
  • Important Warning: Reverse connection will damage the device! Always verify with a multimeter before use.
⑩
  • Power Input: This is the system voltage input that provides stable power to RS485, amplifiers, and other devices.
  • Voltage Warning: Excessive voltage will damage components and ICs due to the numerous connected devices.
  • Recommended Voltage: 24V input is strongly recommended.
  • Polarity Caution: Ensure correct polarity - reverse connection may cause damage.
⑪
  • Purpose: This port supplies power to the onboard stepper motor drivers.
  • Capacitor Rating: Our onboard electrolytic capacitors have a 50V withstand voltage rating.
  • Driver Requirements: Some onboard driver modules contain capacitors with lower voltage tolerance, while others require >12V to generate proper signals.
  • Recommendation: 24V is recommended. Ensure correct polarity to avoid damage.
⑫
  • Function: This jumper selects the VDD logic voltage for stepper motor drivers (onboard or external).
  • SPI Drivers: Since SPI signals are 3.3V, select 3.3V when using SPI-type stepper motors.
  • 5V Drivers: Select 5V for external drivers requiring 5V logic signals.
  • Default Setting: Default position is 3.3V. Choose according to your specific driver requirements.
⑬
  • Function: This is the GPIO.26 function selection jumper.
  • Mode Options: Can be configured as a standard input or as a relay output.
  • Reference: Please refer to the descriptions in Point ① and Point ⑧ for detailed information.
⑭
  • Function: Onboard driver MS1/MS2 configuration switches.
  • Driver Variations: Some drivers support MS1/MS2/MS3, while others only support MS1/MS2.
  • MS3 Configuration: For MS3 setting, configure in YAML file using I2SO output to control pin levels.
  • Naming Note: Some driver boards label these as MS0/MS1/MS2 - set according to actual pin functions.
  • Scope: This MS1/MS2 setting simultaneously configures all 6 onboard drivers.
⑮
  • Function: MS3 pin configuration description and corresponding I2SO numbers.
  • Dual Purpose: Some SPI drivers use the MS3 pin as a Chip Select (CS) signal.
  • Flexibility: These I2SO ports can also be used as CS signals for corresponding SPI drivers.
  • Reference: For specific usage examples, please refer to the detailed documentation.
⑯
  • External Driver Usage: Install these jumpers when using external drivers to output EN, DIR, CLK, and GND signals.
  • C-axis Configuration: Also required when configuring C-axis as external relay output.
  • Primary Function: Routes I2SO signals to the green TBX terminals.
  • CRITICAL WARNING: Never install onboard drivers while these jumpers are inserted! This will damage both your onboard drivers and the mainboard chips.
⑰
  • Onboard Driver Usage: Must remove all corresponding jumpers from the slots when using onboard drivers.
  • Signal Routing: With onboard drivers, the green TBX terminals output signals directly to the motors.
  • Hybrid Configuration: Mixed setup is supported (e.g., slots 1-4 for onboard drivers, slots 5,6 for external relay output).
  • Jumper Placement: Slots 1-4 must have no jumpers; slots 5-6 can have jumpers installed to route I2SO signals for relays to TBX terminals.
⑱
  • Function: Used for external SPI stepper motor driver output.
  • Configuration: When using, remove the SPI jumpers mentioned in Point ⑲ that are intended for onboard drivers.
  • Pin Assignment: V4.96Pro version uses I2SO.3 as the Chip Select (CS) signal.
⑲
  • Function: Installing these jumpers routes SPI signals to the onboard drivers.
  • Design: Arranged in common sequence order, compatible with most TMC drivers.
  • IMPORTANT: When using onboard SPI TMC drivers, remove ALL jumpers mentioned in Point ⑭ to avoid conflicts.
  • Compatibility: TMC drivers and standard drivers cannot be used simultaneously.
⑳
  • Function: This jumper cap inputs USB 5V into the circuit for testing purposes.
  • Important: Please remove it when using an external power supply.
㉑
  • Function: This port, when used with RJ12 or Bluetooth modules, can provide UART signals for pendant control.
  • Connectivity Options: Can connect to expanders via RJ12 modules, or connect to pendant through expanders.
  • Expander Benefit: The expander provides additional I/O inputs and outputs for the mainboard.
  • Compatibility Note: Cannot be used simultaneously with the onboard OLED, as both utilize GPIO.25 and GPIO.27 ports.
㉒
  • Function: This is the onboard OLED display interface.
  • Pinout Caution: Please note the positions of VCC and GND, as some OLED modules have different pin arrangements.
  • Compatibility: The OLED cannot be used simultaneously with expanders or pendant, as they all share the GPIO.25 and GPIO.27 ports.
㉓
  • Component: TF card slot.
  • Compatibility Warning: Avoid using high-speed or high-capacity TF cards, as some may not be compatible with the ESP32 library.
㉔
  • Component: Antenna connector.
  • Important Note: Without an antenna connected, there will be no WiFi signal available.