Baseboard Ports

The baseboard with its port labels: CAN3, T1-ETH, TELEM1 to TELEM3, UART&I2C, DEBUG, RC IN/AUX, POWER1, POWER2 and FMU PWM OUT 1 to 12

The other side of the baseboard with its port labels: AD&IO, CAN2, CAN1, I2C, USB, DSM, NFC, GPS2, GPS1 and SPI

Directions are given from the board: TX (out) leaves the board, RX (in) enters it.

The 5 V on the ports comes from two rails, each with its own current limit. VDD_5V_HIPOWER feeds TELEM1 and GPS2; VDD_5V_PERIPH feeds TELEM2, TELEM3, CAN1, CAN2, CAN3, UART&I2C, GPS1, SPI, I2C, AD&IO.

In standard Pixhawk cables the pin 1 wire is red and the rest are black.

The 2.54 mm headers mark their rows −, + and S: top row A is GND (−), middle row B is power (+), bottom row C is the signal (S). Pins are numbered by position and row, so 3C is the signal pin of position 3.

Ports

Ref	Port	Connector
J16	POWER1	Molex CLIK-Mate, 2.00 mm pitch, 6 pins
J17	POWER2	Molex CLIK-Mate, 2.00 mm pitch, 6 pins
J20	FMU PWM OUT 1-8	2.54 mm right-angle header, 8 positions × 3 rows
J15	FMU PWM OUT 9-12	2.54 mm right-angle header, 4 positions × 3 rows
J13	RC IN / AUX	2.54 mm right-angle header, 2 positions × 3 rows
J5	TELEM1	JST GH, 1.25 mm pitch, 6 pins
J3	TELEM2	JST GH, 1.25 mm pitch, 6 pins
J26	TELEM3	JST GH, 1.25 mm pitch, 6 pins
J9	CAN1	JST GH, 1.25 mm pitch, 4 pins
J10	CAN2	JST GH, 1.25 mm pitch, 4 pins
J6	CAN3	JST GH, 1.25 mm pitch, 4 pins
J21	ETH	JST GH, 1.25 mm pitch, 2 pins
J8	UART & I2C	JST GH, 1.25 mm pitch, 7 pins
J23	FMU DEBUG	JST SH, 1.00 mm pitch, 10 pins
J18	USB-C	Molex USB-C receptacle, right angle, 16 pins
J19	USB	JST GH, 1.25 mm pitch, 4 pins
J4	GPS1	JST GH, 1.25 mm pitch, 10 pins
J7	GPS2	JST GH, 1.25 mm pitch, 6 pins
J11	SPI	JST GH, 1.25 mm pitch, 11 pins
J2	DSM RC	JST ZH, 1.50 mm pitch, 3 pins
J24	I2C	JST GH, 1.25 mm pitch, 4 pins
J14	AD & IO	JST GH, 1.25 mm pitch, 8 pins
J12	NFC	JST GH, 1.25 mm pitch, 2 pins

I2C buses

Bus	Ports	Onboard devices
I2C1	POWER1, GPS1
I2C2	POWER2, GPS2
I2C6	UART & I2C, I2C	24LC64 EEPROM at 7-bit address 0x51, SE052 secure element address 0x48

Power, PWM output and RC input

POWER1 (J16), POWER2 (J17)

Molex CLIK-Mate, 2.00 mm pitch, 6 pins.

Pin	Signal	Level
1	VDD5V	+5 V
2	VDD5V	+5 V
3	SCL	+3.3 V
4	SDA	+3.3 V
5	GND	GND
6	GND	GND

Pins 3 and 4 connect the power module’s voltage and current monitor to the port’s I2C bus.

Port	Role	I2C bus
POWER1	main power input	I2C1
POWER2	backup power input	I2C2

FMU PWM OUT 1-8 (J20), 9-12 (J15)

2.54 mm right-angle header, 12 positions × 3 rows.

Positions are numbered 1 to 12 from right to left.

Pin	Signal	Level
1A to 12A (−)	GND	GND
1B to 12B (+)	VDD_SERVO	external
1C to 12C (S)	FMU_CH1 to FMU_CH12	+3.3 V

Pins 1-8 support DShot.

The board does not power VDD_SERVO; feed the rail from an external supply.

The VDD_SERVO voltage reading is only valid up to 9.9 V.

RC IN / AUX (J13)

2.54 mm right-angle header, 2 positions × 3 rows.

Position 1 is on the right, position 2 on the left.

Pin	Signal	Level
1A	− GND	GND
1B	+ VDD_5V_AUX	+5 V
1C	S AUX out	+3.3 V
2A	− GND	GND
2B	+ VDD_5V_RC	+5 V
2C	S SBUS/PPM in	+3.3 V

Connect the receiver to position 2. The input accepts SBUS or PPM.

Position 1 outputs SBUS, for a device that takes it.

Telemetry, network, serial and debug

TELEM1 (J5), TELEM2 (J3), TELEM3 (J26)

JST GH, 1.25 mm pitch, 6 pins.

Pin	Signal	Level
1	VCC	+5 V
2	TX (out)	+3.3 V
3	RX (in)	+3.3 V
4	CTS (in)	+3.3 V
5	RTS (out)	+3.3 V
6	GND	GND

All three support hardware flow control. TELEM1 shares its 5 V rail only with GPS2, so it is the port for the telemetry radio that draws the most current.

Port	UART	Pin 1 rail
TELEM1	UART4	VDD_5V_HIPOWER
TELEM2	UART8	VDD_5V_PERIPH
TELEM3	UART10	VDD_5V_PERIPH

CAN1 (J9), CAN2 (J10), CAN3 (J6)

JST GH, 1.25 mm pitch, 4 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	CANH1 to CANH3	+3.3 V
3	CANL1 to CANL3	+3.3 V
4	GND	GND

Three independent buses.

ETH (J21)

JST GH, 1.25 mm pitch, 2 pins.

Pin	Signal	Level
1	TRX_P	differential
2	TRX_N	differential

100BASE-T1. One twisted pair carries both directions, so there are no separate transmit and receive pins.

The PHY is strapped as master in autonomous mode, so the link partner must be the slave.

UART & I2C (J8)

JST GH, 1.25 mm pitch, 7 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	TX (out)	+3.3 V
3	RX (in)	+3.3 V
4	SCL (I2C6)	+3.3 V
5	SDA (I2C6)	+3.3 V
6	NFC_GPIO	+3.3 V
7	GND	GND

Labelled EXTERNAL 2 on the schematic. UART11 plus I2C6.

FMU DEBUG (J23)

JST SH, 1.00 mm pitch, 10 pins.

Pin	Signal	Level
1	FMU_VDD_3V3	+3.3 V
2	FMU_USART_TX	+3.3 V
3	FMU_USART_RX	+3.3 V
4	FMU_SWD_IO	+3.3 V
5	FMU_SWD_CK	+3.3 V
6	SPI6_MOSI	+3.3 V
7	NFC_GPIO	+3.3 V
8	GPIO_EMC_B2_12	+3.3 V
9	FMU_nRST	+3.3 V
10	GND	GND

Console and SWD debug probe.

USB-C (J18)

Molex USB-C receptacle, right angle, 16 pins.

Pin	Signal	Level
A1	GND	GND
A4	VBUS	+5 V
A5	CC1	+3.3 V
A6	DP	differential
A7	DM	differential
A8	SBU1	not connected
A9	VBUS	+5 V
A12	GND	GND
B1	GND	GND
B4	VBUS	+5 V
B5	CC2	+3.3 V
B6	DP	differential
B7	DM	differential
B8	SBU2	not connected
B9	VBUS	+5 V
B12	GND	GND

USB (J19)

JST GH, 1.25 mm pitch, 4 pins.

Pin	Signal	Level
1	VBUS	+5 V
2	DM	differential
3	DP	differential
4	GND	GND

The same USB signals as the USB-C receptacle, on a header beside it. Use one or the other, not both.

GNSS, SPI, RC, I2C and analogue IO

GPS1 (J4)

JST GH, 1.25 mm pitch, 10 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	TX (out)	+3.3 V
3	RX (in)	+3.3 V
4	SCL (I2C1)	+3.3 V
5	SDA (I2C1)	+3.3 V
6	SAFETY_SWITCH	+3.3 V
7	SAFETY_SWITCH_LED	+3.3 V
8	VDD_3V3	+3.3 V
9	BUZZER	0 to 5 V
10	GND	GND

UART3 and I2C1, plus the safety switch and the buzzer. This is the port for a GPS module with a compass and a safety switch with LED.

Wire the buzzer between pin 9 and a 5 V pin: pin 9 switches to GND to sound it.

GPS2 (J7)

JST GH, 1.25 mm pitch, 6 pins.

Pin	Signal	Level
1	VCC (VDD_5V_HIPOWER)	+5 V
2	TX (out)	+3.3 V
3	RX (in)	+3.3 V
4	SCL (I2C2)	+3.3 V
5	SDA (I2C2)	+3.3 V
6	GND	GND

UART5 and I2C2, for a second GPS module with a compass.

SPI (J11)

JST GH, 1.25 mm pitch, 11 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	SPI_SCK	+3.3 V
3	SPI_MISO	+3.3 V
4	SPI_MOSI	+3.3 V
5	SPI_CS1	+3.3 V
6	SPI_CS2	+3.3 V
7	SPI_SYNC	+3.3 V
8	SPI_DRDY1	+3.3 V
9	SPI_DRDY2	+3.3 V
10	SPI_nRESET	+3.3 V
11	GND	GND

External SPI sensors. Two chip selects, so two devices can share the port.

DSM RC (J2)

JST ZH, 1.50 mm pitch, 3 pins.

Pin	Signal	Level
1	VDD_3V3_SPEKTRUM	+3.3 V
2	GND	GND
3	DSM/SPEKTRUM IN	+3.3 V

Spektrum receiver, powered at 3.3 V.

This shares its input with position 2 of the RC IN / AUX header. Connect a receiver to either, never both.

I2C (J24)

JST GH, 1.25 mm pitch, 4 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	SCL (I2C6)	+3.3 V
3	SDA (I2C6)	+3.3 V
4	GND	GND

AD & IO (J14)

JST GH, 1.25 mm pitch, 8 pins.

Pin	Signal	Level
1	VCC (VDD_5V_PERIPH)	+5 V
2	FMU_CAP	+3.3 V
3	FMU_BOOTLOADER	+3.3 V
4	FMU_RST_REQ	+3.3 V
5	NARMED	+3.3 V
6	ADC1_3V3	0 to 3.3 V
7	ADC1_6V6	0 to 6.6 V
8	GND	GND

Analogue inputs and control lines. Pin 7 shares an ADC channel with the VDD_SERVO rail measurement; use one or the other.

NFC (J12)

JST GH, 1.25 mm pitch, 2 pins.

Pin	Signal	Level
1	LB	coil
2	LA	coil

NFC antenna coil for the onboard secure element.