ardupilot/libraries/AP_HAL_ChibiOS/hwdef/RADIX2HD

BrainFPV RADIX 2 HD Flight Controller

The BrainFPV RADIX 2 HD is a flight controller primarily intended for First Person View (FPV) applications that use a HD (digital) FPV system.

For the full documentation, refer to the BrainFPV website.

Features

• STM32H750 microcontroller
• IMU: Bosch Sensortec BMI270
• Barometer: Infineon DPS310
• Onboard flash: 16 MB connected via QUADSPI
• microSD slot
• 6 UARTs plus USB (7 UARTs with alternate board config)
• 10 PWM outputs (8 supporting BDSHOT on dual 4-in-1 ESC connectors)
• I2C and CAN port
• Builtin RGB LED
• Analog input for voltage sensing, up to 12S (52 V)
• Analog input for current sensing
• Analog input for RSSI
• External buzzer
• USB Type-C connector
• Battery voltage 3S-8S (35 V)
• 5 V / 1.5 A voltage regulator for powering flight controller and external devices
• 9 V / 2 A voltage regulator for HD FPV system (can be turned on/off using the Relay2 switch)
• Size: 37 x 37 mm (30.5 mm hole spacing)
• Weight: 7g
• Made in the USA, NDAA compliant

Pinout

Refer to the full documentation for details and how to use the "PWR:VBAT" jumper.

UART Mapping

• SERIAL0 -> USB
• SERIAL1 -> UART1 (DMA-enabled, MSP DisplayPort OSD)
• SERIAL2 -> UART2 (DMA-enabled, GPS)
• SERIAL3 -> UART3 (DMA-enabled, RCin)
• SERIAL4 -> UART4 (ESC telemetry)
• SERIAL5 -> UART5 (spare)
• SERIAL6 -> UART6 (spare, PWM 9 and 10 by default, use BRD_ALT_CONFIG = 1 for UART)
• SERIAL7 -> UART7 (spare, RX is on HD connector for RC input, TX is not connected to external pad)

RC Input

By default, SERIAL3 is used for RC input. The RC receiver 5 V pad next to RX3 ("+") is also powered from USB for easy and safe configuration without having to connect the main battery.

PWM Output

The RADIX 2 HD has a total of 10 PWM outputs. The first 8 outputs support BDSHOT and are on two 4-in-1 ESC connectors. The PWM outputs are in groups of 2 channels each, all channels in the same group need to use the same configuration / rate.

• PWM 1-2 Group 1
• PWM 3-4 Group 2
• PWM 5-6 Group 3
• PWM 7-8 Group 4
• PWM 9-10 Group 5 (These are on the TX6 and RX6 pads that can also be used for SERIAL6)

Analog inputs

The RADIX 2 HD has 3 analog inputs:

• ADC Pin 10 -> Battery Voltage (VBAT pin, builtin 1:17.6 voltage divider)
• ADC Pin 3 -> Battery Current Sensor (CUR pin)
• ADC Pin 11 -> RSSI voltage monitoring (RSSI pad)

Battery Monitoring

The RADIX 2 HD can monitor battery voltages up to 12S using a built-in voltage divider. The board itself can be powered by battery voltages up to 8S (35 V) and there is a jumper to use the same pin for battery voltage monitoring and for powering the board.

WARNING Powering the board with more than 8S (35 V) with the "PWR:VBAT" jumper soldered will damage it. Refer to the official documentation for more details.

In addition to voltage sensing, the board also has an input for an external current sensor.

Loading Firmware

The RADIX 2 HD uses a proprietary bootloader which needs a firmware file in a custom file format. There are several ways of obtaining the firmware file, as explained below. Once you have obtained the file, copy it to the USB drive that appears when connecting the RADIX 2 HD to your computer when it is in bootloader mode (hold the BOOT button and release when connecting to USB). Once it finishes copying, safely remove the drive. At this point the RADIX 2 HD will reboot and run the ArduPilot firmware.

Note: When using ArduPilot, it is necessary to have a microSD card inserted, without it the firmware won't run.

Option 1: Download the Firmware File the BrainFPV Website

The easiest way to get firmware files for your RADIX 2 HD is to download them from the BrainFPV website. You can do so here.

Option 2: Download the Firmware From the ArduPilot Build Server

Download the ELF file from the ArduPilot Build Server. Make sure you download the file for the "RADIX2HD" target. For example, the ELF file for ArduCopter is called "arducopter.elf".

In order to use the ELF file with your RADIX 2 HD, it needs to be converted using the BrainFPV Firmware Packer. This utility is implemented in Python, so you will need a Python installation.

If you are using Linux, use your package manager to install Python 3. If you are using Windows, download the Python 3 installer from the Python Website and run it. When installing, make sure to select "Add Python to PATH", so you will be able to use Python from the Windows Command Prompt.

After installing Python, start the Command Prompt and install the BrainFPV Firmware Packer using the following command:

python3 -m pip install https://github.com/BrainFPV/brainfpv_fw_packer/archive/main.zip

After installing it, you can use the following command to convert the "arducopter.elf" (or other vehicle elf file) file to a "arducopter.bin" file that can be used with the RADIX 2 HD:

brainfpv_fw_packer.py --name arducopter --in arducopter.elf --out arducopter.bin ^
                      --dev radix2hd -t firmware -b 0x90400000 -z --noheader

Option 3: Compile the Firmware Yourself

If you have a working ArduPilot build environment, you can compile the firmware yourself and then convert it to the format needed by the BrainFPV bootloader. You will also need the BrainFPV Firmware Packer to do so. Install it using the "pip install" command shown above.

For Copter, build the firmware as follows:

./waf configure --board RADIX2HD
./waf copter

other vehicles can be built, but the RADIX 2 HD is used primarily for copter applications. Then use the firmware packer script to create the firmware file that can be used with the BrainFPV bootloader:

./libraries/AP_HAL_ChibiOS/hwdef/RADIX2HD/pack_firmware.sh copter

To use it, copy the resulting arducopter_{VERSION}_brainfpv.bin to the USB drive that appears when the RADIX 2 HD is in bootloader mode.