# mRo Pixracer


PX4 does not manufacture this (or any) autopilot. Contact the manufacturer (opens new window) for hardware support or compliance issues.

The Pixhawk® XRacer board family is optimized for small racing quads and planes. In contrast to Pixfalcon and Pixhawk it has in-built WiFi, new sensors, convenient full servo headers, CAN and supports 2M flash.


This autopilot is supported by the PX4 maintenance and test teams.

# Key Features

  • Main System-on-Chip: STM32F427VIT6 rev.3 (opens new window)
    • CPU: 180 MHz ARM Cortex® M4 with single-precision FPU
    • RAM: 256 KB SRAM (L1)
  • Standard FPV form factor: 36x36 mm with standard 30.5 mm hole pattern
  • Invensense® ICM-20608 Accel / Gyro (4 KHz) / MPU9250 Accel / Gyro / Mag (4 KHz)
  • HMC5983 magnetometer with temperature compensation
  • Measurement Specialties MS5611 barometer
  • JST GH connectors
  • microSD (logging)
  • Futaba S.BUS and S.BUS2 / Spektrum DSM2 and DSMX / Graupner SUMD / PPM input / Yuneec ST24
  • FrSky® telemetry port
  • OneShot PWM out (configurable)
  • Optional: Safety switch and buzzer

# Where to Buy

Pixracer is available from the mRobotics.io (opens new window).

Accessories include:

# Kit

The Pixracer is designed to use a separate avionics power supply. This is necessary to avoid current surges from motors or ESCs to flow back to the flight controller and disturb its delicate sensors.

  • Power module (with voltage and current sensing)
  • I2C splitter (supporting AUAV, Hobbyking and 3DR® peripherals)
  • Cable kit for all common peripherals

# Wifi (no USB required)

One of the main features of the board is its ability to use Wifi for flashing new firmware, system setup and in-flight telemetry. This frees it of the need of any desktop system.


Firmware upgrade is not yet enabled over WiFi (it is supported by the default bootloader but not yet enabled). Setup and telemetry are supported.

# Assembly

See the Pixracer Wiring Quickstart

# Wiring Diagrams

Grau setup pixracer top


If using TELEM2 for an external telemetry module you will need to configure it as a MAVLink serial port. For more information see: Pixracer Wiring Quickstart > External Telemetry

Grau setup pixracer bottom

setup pixracer GPS

Grau b Pixracer FrSkyS.Port Connection

Grau ACSP4 2 roh

Grau ACSP5 roh

# Connectors

All connectors follow the Pixhawk connector standard (opens new window). Unless noted otherwise all connectors are JST GH.

# Pinouts

Pixracer top pinouts

Pixracer bottom pinouts

Pixracer esp

# TELEM1, TELEM2+OSD ports

Pin Signal Volt
1 (red) VCC +5V
2 (blk) TX (OUT) +3.3V
3 (blk) RX (IN) +3.3V
4 (blk) CTS (IN) +3.3V
5 (blk) RTS (OUT) +3.3V
6 (blk) GND GND

# GPS port

Pin Signal Volt
1 (red) VCC +5V
2 (blk) TX (OUT) +3.3V
3 (blk) RX (IN) +3.3V
4 (blk) I2C1 SCL +3.3V
5 (blk) I2C1 SDA +3.3V
6 (blk) GND GND

# FrSky Telemetry / SERIAL4

Pin Signal Volt
1 (red) VCC +5V
2 (blk) TX (OUT) +3.3V
3 (blk) RX (IN) +3.3V
4 (blk) GND GND

# RC Input (accepts PPM / S.BUS / Spektrum / SUMD / ST24)

Pin Signal Volt
1 (red) VCC +5V
2 (blk) RC IN +3.3V
3 (blk) RSSI IN +3.3V
4 (blk) VDD 3V3 +3.3V
5 (blk) GND GND


Pin Signal Volt
1 (red) VCC +5V
2 (blk) CAN_H +12V
3 (blk) CAN_L +12V
4 (blk) GND GND


Pin Signal Volt
1 (red) VCC +5V
2 (blk) VCC +5V
3 (blk) CURRENT +3.3V
4 (blk) VOLTAGE +3.3V
5 (blk) GND GND
6 (blk) GND GND


Pin Signal Volt
1 (red) SAFETY GND
3 (blk) VCC +3.3V
4 (blk) BUZZER- -
5 (blk) BUZZER+ -

# Debug Port

This is a Pixhawk Debug Port (opens new window) (JST SM06B connector).

Pin Signal Volt
1 (red) VCC TARGET SHIFT +3.3V
2 (blk) CONSOLE TX (OUT) +3.3V
3 (blk) CONSOLE RX (IN) +3.3V
4 (blk) SWDIO +3.3V
5 (blk) SWCLK +3.3V
6 (blk) GND GND

For information about wiring and using this port see:

# Serial Port Mapping

UART Device Port
UART1 /dev/ttyS0 WiFi (ESP8266)
USART2 /dev/ttyS1 TELEM1 (flow control)
USART3 /dev/ttyS2 TELEM2 (flow control)

# Schematics

The reference is provided as: Altium Design Files (opens new window)

The following PDF files are provided for convenience only:

# Building Firmware


Most users will not need to build this firmware! It is pre-built and automatically installed by QGroundControl when appropriate hardware is connected.

To build PX4 for this target:

make px4_fmu-v4_default

# Credits

This design was created by Nick Arsov and Phillip Kocmoud and architected by Lorenz Meier, David Sidrane and Leonard Hall.