Pixracer

The Pixracer is the first autopilot of the FMUv4 Pixhawk generation. It comes with a small Wifi extension board.

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Overview

The Pixracer is the common name for the FMUv4 generation of Pixhawk autopilots. It has been designed primarily for the demanding requirements of small multicopters, but of course can be used on planes and other vehicles which require no more than 6 pwm outputs for controlling escs and motors. Pixracer is available from the mRobotics

Tip

At time of writing the autopilot is still being evolved/improved. The final version may very slightly from the information provided here.

This video below provides a detailed overview of the board. Additional information can be found on pixhawk.org and the mRobotics.

Specifications

  • Processor:

    • MCU - STM32F427VIT6 rev.3

    • Ultra low noise LDOs for sensors and FMU

    • FRAM - FM25V02-G

  • Sensors

    • Gyro/Accelerometer: Invensense MPU9250 Accel / Gyro / Mag (4 KHz)

    • Gyro/Accelerometer: Invensense ICM-20608 Accel / Gyro (4 KHz)

    • Barometer: MS5611

    • Compass: Honeywell HMC5983 magnetometer with temperature compensation

  • Power

  • Interfaces/Connectivity

    • Wifi: ESP-01 802.11bgn Flashed with MavESP8266

    • MicroSD card reader

    • Micro USB

    • RGB LED

    • GPS (serial + I2C)

    • TELEM1/TELEM2

    • Wifi serial

    • FrSky Telemetry serial(see note)

    • Debug connector (serial + SWD)

    • Connectors: GPS+I2C, RC-IN, PPM-IN, RSSI, SBus-IN, Spektrum-IN, USART3 (TxD, RxD, CTS, RTS), USART2 (TxD, RxD, CTS, RTS), FRSky-IN, FRSky-OUT, CAN, USART8 (TxD, RxD), ESP8266 (full set), SERVO1-SERVO6, USART7 (TxD, RxD), JTAG (SWDIO, SWCLK), POWER-BRICK (VDD, Voltage, Current, GND), BUZZER-LED_BUTTON.

  • Dimensions

    • Weight ?

    • 36 x 36mm with 30.5 x 30.5mm hole grid with 3.2mm holes

Note

The FrSky telemetry port is implemented using a 74LVC2G86 NOR gate as a programmable inverter to both the RX and TX lines. See below for use information.

Connector pin assignments

Unless noted otherwise all connectors are JST GH

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

This port has built in inverters on the TX and RX lines and shunt resistors which allow them to be tied together and connected to an FrSky receiver’s SPort input for telemetry. It is on by default, and only SERIAL4_PROTOCOL needs to be set to “10” for FrSky passthrough telemetry to be sent to the receiver. See FrSky Telemetry for more information.

The operation of the TX/RX path inverter can be disabled by setting the SERIAL4_OPTIONS parameter to “2” to “invert” the TX , which will turn off the inversion for both the TX and RX pins. This will allow normal UART operation, if desired.

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

CAN

PIN SIGNAL VOLT
1 (red) VCC +5V
2 (blk) CAN_H +12V
3 (blk) CAN_L +12V
4 (blk) GND GND

Power

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

Switch

PIN SIGNAL VOLT
1 (red) SAFETY GND
2 (blk) !IO_LED_SAFETY GND
3 (blk) CURRENT +3.3V
4 (blk) BUZZER- -
5 (blk) BUZZER+ -

Debug port (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

Where to Buy

  • We suggest buying directly from mRobotics.

  • Whilst PixRacer can be sourced from other retailers, the specific design may differ and not have been tested by the Development Team. Known retailers of 3rd party PixRacer boards are HobbyKing, and Banggood, …

See also

Note

Some information and images in this page were copied from pixhawk.org, docs.px4.io and the mRobotics shop

Schematics