Pinout

Note

• This page lists the pinout of the FLY-Gemini V3 mainboard after flashing Klipper firmware, with pin numbers based on the mainboard schematic.
• UART/CS is the driver communication pin: used as UART when using TMC2209, or as chip select CS when using SPI drivers such as TMC5160, with the same pin being multiplexed.
• EN is the enable pin, typically active low in Klipper configuration (enable_pin with a ! prefix).
• DIAG is the driver diagnostic signal pin. When using sensorless homing, configure the corresponding diag_pin according to the table below.

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Interactive Pin Hotspots

The image below uses the FLY-Gemini V3 product image and the same hotspot data from the Klipper configuration generator. Use the device filters above to show only compatible connectors; click a hotspot to see compatible devices, common Klipper configuration sections, and notes. Use “Locate in pin table” in the detail panel to jump to and highlight the corresponding row below. Hover still shows the connector name and pin. Always verify the silkscreen and connector positions against the physical board and schematic.

Filter by deviceClick a device type to show only connectors that support it; click again to clear the filter.

FLY-Gemini V3Motor driversHeatersThermistorsFansEndstopsProbe / servo

Hover to see the pin; click a hotspot to view compatible devices and configs. Pins can be copied from the detail panel, except for driver connectors.

Driver Pins

The FLY-Gemini V3 provides 4 driver ports:

Driver	STEP	DIR	EN	UART/CS	DIAG
DRIVER0	PC13	PC1	PA3	PB11	PA4
DRIVER1	PC14	PC4	PD2	PC10	PA5
DRIVER2	PC15	PC5	PC12	PB7	PA6
DRIVER3	PC3	PC8	PC11	PB6	PB1

Power-off Operation

Before starting, completely shut down the printer and disconnect the power supply. Do not plug or unplug cables, organize wiring sequences, or touch terminals while the system is powered on.

DIAG and Sensorless Homing

When using sensorless homing, the driver chip outputs the stall detection signal through the DIAG pin, and Klipper needs to read this signal via the corresponding input port. The correspondence between DIAG and endstop ports on this mainboard is as follows:

• DRIVER0–3: DIAG is directly connected to the corresponding endstop input port on the main controller (DRIVERn → Endstop Port n). There are no DIAG jumper pins on the board, and the DIAG signal is always delivered to the main controller. When enabling sensorless homing, simply configure the corresponding endstop port pin as diag_pin. Do not connect a physical endstop switch to that endstop port.

Once sensorless homing is enabled, the corresponding endstop port is occupied by the DIAG signal, and mechanical or optical endstop switches must not be connected simultaneously.

SPI Bus

SPI drivers such as the TMC5160 use the mainboard's hardware SPI bus. In the configuration, simply set spi_bus: spi3; no need to separately configure MOSI/MISO/SCLK pins:

[tmc5160 stepper_x]
spi_bus: spi3
cs_pin: corresponding driver's UART/CS pin

Detailed instructions on software SPI and SPI speed: SPI Configuration Method

Endstops and Probe

Function	Pin	Corresponding Driver DIAG
Endstop Port 0 / IO0	PA4	DRIVER0
Endstop Port 1 / IO1	PA5	DRIVER1
Endstop Port 2 / IO2	PA6	DRIVER2
Endstop Port 3 / IO3	PB1	DRIVER3
Probe	PA1	-

For wiring of micro switches, optical endstops, proximity sensors, and TAP, see: Endstop Wiring Guide

Heating

Function	Pin
Heater Port 0	PA0
Heated Bed	PA2

Temperature Sensors

Function	Pin
Thermistor Port 0	PC0
Thermistor Port 1	PC2

Supported Thermistor Types

The thermistor ports support NTC thermistors (100K) by default, with sensor_type recommended as Generic 3950; they also support 2-wire PT1000, configured by setting sensor_type to PT1000.

List of sensor_type options that can be directly connected internally by Klipper and their applicable scenarios: Thermistor Configuration Method

K-type thermocouples, 3-wire PT100, etc., require additional signal conditioning chips and cannot be connected directly to the thermistor ports.

Fans

Function	Pin
Fan Port 0	PC6
Fan Port 1	PC7

PWM

The FLY-Gemini V3 provides 1 PWM output, which can be used for servos, fan speed control, etc.:

Pin	Remarks
PB0	Servo / BLTouch control

BL-Touch

Function	Pin
Servo signal	PB0
Probe signal	PA1

EXP Interface

EXP Configuration Reminder

• The EXP header is commonly used for screens like the Mini12864 or other expansion peripherals.
• If a pin is already occupied by SPI, UART, endstop, fan, or other functions, do not reconfigure it in EXP peripherals.

EXP1

Function	Pin
EXP1_1	PC9
EXP1_2	PB10
EXP1_3	PA13
EXP1_4	PA10
EXP1_5	PA9
EXP1_6	PA8
EXP1_7	NC
EXP1_8	NC
EXP1_9	GND
EXP1_10	5V

EXP2

Function	Pin
EXP2_1	PB14
EXP2_2	PB13
EXP2_3	PA15
EXP2_4	PB12
EXP2_5	PA14
EXP2_6	PB15
EXP2_7	PA7
EXP2_8	RST
EXP2_9	GND
EXP2_10	NC