Pin Distribution

Note

• This page lists the pin distribution of the FLY-Gemini V2 motherboard after flashing Klipper firmware. The pin numbers are based on the motherboard schematic.
• The pins of Gemini V2 and Gemini V3 are not exactly the same. Do not mix the configurations of the two boards.
• UART/CS is the driver communication pin: when using TMC2209, it serves as UART; when using SPI drivers such as TMC5160, it serves as the chip select CS. The same pin is shared.
• EN is the enable pin. In Klipper configuration, it is usually active low (with the enable_pin prefixed by !).

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Driver Pins

The FLY-Gemini V2 provides 4 driver ports:

Driver	STEP	DIR	EN	UART/CS
X	PC13	PC1	PB2	PB11
Y	PC14	PC4	PD2	PB9
Z	PC15	PC5	PC12	PB8
E	PC3	PC8	PC11	PB7

Power Off Operation

Before starting, completely turn off the printer and disconnect the power supply. Do not plug or unplug cables, organize wiring, or touch terminals while the power is on.

Driver Configuration Reminder

• enable_pin usually needs to be written in active-low form, such as !PB2, !PD2, !PC12, and !PC11.
• The sense_resistor for TMC drivers should be based on the actual driver board parameters, not merely copied from the chip model.
• When using endstopless homing, confirm the DIAG signal according to the actual driver module and endstop port wiring. Do not connect a physical endstop switch to the endstop port occupied by DIAG.

SPI Bus

SPI drivers such as the TMC5160 use the motherboard's hardware SPI bus:

Function	Pin
MOSI	PB5
MISO	PB4
SCLK	PB3
CS	Corresponding driver's UART/CS pin

Configuration example:

[tmc5160 stepper_x]
spi_bus: spi3
cs_pin: PB11

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

Endstops and Probe

Function	Pin
X Endstop	PA3
Y Endstop	PB1
Z Endstop	PB10
Probe	PA1

Heating

Function	Pin
Extruder Heater	PA0
Heated Bed Heater	PA2

Temperature Sensors

Function	Pin
Extruder Temperature	PC0
Heated Bed Temperature	PC2

Supported Thermistor Types

The thermistor port supports NTC thermistors (100K) by default. It is recommended to configure sensor_type as Generic 3950.

List of built-in sensor_type options in Klipper that can be directly connected and their applicable scenarios: Thermistor Configuration Method

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

Fans

Function	Pin
Fan Port 0	PC6
Fan Port 1	PC7

Servo and 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 expanded peripherals.
• If a pin is already occupied by SPI, UART, endstop, fan, or other functions, do not configure it again in the EXP peripherals.

EXP1

Function	Pin
EXP1_1	PC9
EXP1_2	PB6
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	PC10
EXP2_8	RST
EXP2_9	GND
EXP2_10	NC

Common Configuration Reminders

• When connecting to the host via USB, use serial in [mcu].
• When connecting to the host via CAN, use canbus_uuid in [mcu] and delete or comment out serial.