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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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Driver Pins​

The FLY-Gemini V3 provides 4 driver ports:

DriverSTEPDIRENUART/CSDIAG
DRIVER0PC13PC1PA3PB11PA4
DRIVER1PC14PC4PD2PC10PA5
DRIVER2PC15PC5PC12PB7PA6
DRIVER3PC3PC8PC11PB6PB1
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​

FunctionPinCorresponding Driver DIAG
Endstop Port 0 / IO0PA4DRIVER0
Endstop Port 1 / IO1PA5DRIVER1
Endstop Port 2 / IO2PA6DRIVER2
Endstop Port 3 / IO3PB1DRIVER3
ProbePA1-

Heating​

FunctionPin
Heater Port 0PA0
Heated BedPA2

Temperature Sensors​

FunctionPin
Thermistor Port 0PC0
Thermistor Port 1PC2
Supported Thermistor Types

The thermistor ports support NTC thermistors (100K) by default, and the recommended sensor_type configuration is Generic 3950.

Klipper's built-in list of directly connectable sensor_type options and their applicable scenarios: Thermistor Configuration Method

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

Fans​

FunctionPin
Fan Port 0PC6
Fan Port 1PC7

PWM​

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

PinRemarks
PB0Servo / BLTouch control

BL-Touch​

FunctionPin
Servo signalPB0
Probe signalPA1

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​

FunctionPin
EXP1_1PC9
EXP1_2PB10
EXP1_3PA13
EXP1_4PA10
EXP1_5PA9
EXP1_6PA8
EXP1_7NC
EXP1_8NC
EXP1_9GND
EXP1_105V

EXP2​

FunctionPin
EXP2_1PB14
EXP2_2PB13
EXP2_3PA15
EXP2_4PB12
EXP2_5PA14
EXP2_6PB15
EXP2_7PA7
EXP2_8RST
EXP2_9GND
EXP2_10NC
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