Pin Layout

Note

• This page lists the pin layout of the FLY-E3 Ultra motherboard after flashing Klipper firmware. The pin numbers are based on the motherboard schematic.
• UART/CS is the driver communication pin: it acts as UART when using TMC2209, and as chip select CS when using SPI drivers such as TMC5160. The same pin is multiplexed.
• EN is the enable pin. In Klipper configuration, it is typically active-low (with the ! prefix in enable_pin).
• 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-E3 Ultra provides 5 driver ports:

Driver	STEP	DIR	EN	UART/CS	DIAG
DRIVER0	PC13	PC0	PC15	PC14	-
DRIVER1	PE3	PE2	PE5	PE4	PD12
DRIVER2	PD1	PD0	PE1	PE0	PB10
DRIVER3	PA15	PD7	PC2	PA8	PC4
DRIVER4	PD4	PD3	PD6	PD5	-

Power Off Before Operation

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

DIAG and Sensorless Homing

In the table, rows where the Corresponding Driver DIAG is not - indicate that the driver's DIAG signal is already connected to the corresponding input port on the main controller. When enabling sensorless homing, configure diag_pin directly according to the table. The corresponding input port will be occupied by the DIAG signal, so do not connect mechanical or optical endstop switches simultaneously. Drivers without a listed DIAG mapping cannot be configured for sensorless homing directly according to the table.

Endstops and Probe

Function	Pin	Corresponding Driver DIAG
Endstop Port 0 / IO0	PD12	DRIVER1
Endstop Port 1 / IO1	PB10	DRIVER2
Endstop Port 2 / IO2	PC4	DRIVER3
Probe	PC5	-

Heating

Function	Pin
Heated Bed	PA0
Heater Port 0	PA2
Heater Port 1	PC6

Temperature Sensors

Function	Pin
Bed Thermistor	PA3
Thermistor Port 0	PA4
Thermistor Port 1	PA1

Supported Thermistor Types

The thermistor ports support NTC thermistors (100K) by default. It is recommended to set sensor_type to Generic 3950.

List of sensor_type options built into Klipper that can be connected directly, along with their applicable scenarios: Thermistor Configuration Method

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

Fans

Function	Pin
Fan Port 0	PD15
Fan Port 1	PD14
Fan Port 2	PB6
Fan Port 3	PB7

PWM

The FLY-E3 Ultra provides 5 channels of PWM output, which can be used for servos, fan speed control, etc.:

Pin	Remark
PB0	Servo / BLTouch control
PD10	PWE-DE
PB1	LASER
PD11	PS-ON
PB11	RGB / Neopixel

BL-Touch

Function	Pin
Servo Signal	PB0
Probe Signal	PC5

RGB

Function	Pin
RGB / Neopixel	PB11