Pixracer Pro

The Pixracer Pro is the next generation autopilot of mRo’s Pixracer family.

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Overview

The Pixracer Pro is the next generation of mRobotics’ family of Pixracer 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 8 pwm outputs for controlling escs and motors.

Tip

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

Specifications

  • Processor:
    • MCU - STM32H743IIK6
    • 2MB flash allows full features of ArduPilot to be flashed
    • 256KB FRAM - FM25V02-G
  • Sensors
    • Gyro/Accelerometer: Invensense ICM-20948 / Gyro / Mag (? KHz)
    • Gyro/Accelerometer: Invensense ICM-20602 Accel / Gyro (? KHz)
    • Gyro/Accelerometer: Bosch BMI088 Accel / Gyro (? KHz)
    • Barometer: DSP310
  • Power
    • 5-5.5VDC from USB or PowerBrick connector. Optional/recommended ACSP4 +5V/+12V Power Supply.
    • Ultra low noise LDOs for sensors and FMU
  • Interfaces/Connectivity
    • MicroSD card reader
    • Micro-C USB
    • RGB LED
    • GPS (serial + I2C)
    • TELEM1/TELEM2
    • FrSky Telemetry serial port
    • On-Board Buzzer
    • 8 Servo/Motor Outputs, 3.3V (default) or 5V level selectable (GPIO 74)
    • Connectors: GPS+I2C (USART4), RC-IN/PPM-IN/RSSI/SBus-IN/Spektrum-IN, USART3 (TxD, RxD, CTS, RTS), USART2 (TxD, RxD, CTS, RTS), USART8(FRSky-IN/FRSky-OUT), CAN1, CAN2, SERVO1-SERVO8, USART1/USART7 (TxD, RxD), SPI6, POWER-BRICK (VDD, Voltage, Current, GND).
  • Dimensions
    • Weight ?
    • Size

Connector pin assignments

Unless noted otherwise all connectors are JST GH

USART2,USART3 (TELEM1/TELEM2)connectors

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V +5V
2 TX +3.3V/5V
3 RX +3.3V/5V
2 CTS +3.3V
3 RTS +3.3V/5V
6 GND GND

UART1/UART7 connector

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V +5V
2 TX1 +3.3V/5V
3 RX1 +3.3V/5V
4 GND GND
5 +5V +5V
6 TX7 +3.3V/5V
7 RX7 +3.3V/5V
8 GND GND

USART4 (GPS+I2C) connector

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V +5V
2 TX +3.3V/5V
3 RX +3.3V/5V
4 SCL +3.3V/5V
5 SDA +3.3V/5V
6 GND GND

USART8 (FrSky Telemetry)

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V +5V
2 TX +3.3V/5V
3 RX +3.3V/5V
4 GND GND

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

PIN SIGNAL VOLTAGE/TOLERANCE
1 +4.5V +4.5V **
2 RC input (USART6 RX) +3.3V/5V
3 RSSI input +3.3V/5V
4 +3.3V +3.3V (for Spektrum RX power)
5 GND GND

** normally supply outputs only valid when power module is powered, but this output is also active when USB is connected.

CAN1 and CAN2 connectors

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V +5V
2 CH +3.3V/5V
3 CL +3.3V/5V
4 GND GND

Power connector

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V in +5V
2 +5V in +5V
3 CURR sense in +3.3V/5V
4 VOLT sense in +3.3V/5V
5 GND GND
6 GND GND

SPI6 connector

PIN SIGNAL VOLTAGE/TOLERANCE
1 +5V in +5V
2 MISO +3.3V/5V
3 SCK +3.3V/5V
4 CS +3.3V/5V
5 MOSI +3.3V/5V
6 GND GND

Default UART order

Parameter Default Protocol** Connector
SERIAL0 console USB
SERIAL1 Telemetry1 USART2 (supports CTS and RTS signaling)
SERIAL2 Telemetry2 USART3 (supports CTS and RTS signaling)
SERIAL3 GPS1 UART4
SERIAL4 GPS2 UART8 (targeted for FrSky Telem, but must change SERIAL4_PROTOCOL)
SERIAL5 USER USART1
SERIAL6 USER UART7
SERIAL7 SLCAN USB (second composite USB interface)

** User may change SERIALx_PROTOCOL as required for application

Dshot capability

All motor/servo outputs are Dshot and PWM capable. However, mixing Dshot and normal PWM operation for outputs is restricted into groups, ie. enabling Dshot for an output in a group requires that ALL outputs in that group be configured and used as Dshot, rather than PWM outputs. The output groups that must be the same (PWM rate or Dshot, when configured as a normal servo/motor output) are: 1/2/3/4, 5/6, and 7/8.

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