PX4 User Guide

# Bootloader Flashing onto Betaflight Systems

This page documents how to flash the PX4 bootloader onto boards preflashed with Betaflight (e.g. OmnibusF4 SD or Kakute F7).

There are two options for flashing the bootloader: via Betaflight Configurator (easier), or building from source.

# Bootloader Update using Betaflight Configurator

To install the PX4 bootloader using the Betaflight Configurator:

  1. You should have downloaded already the pre-built bootloader binary (this depends on the board you want to flash).
  2. Download the Betaflight Configurator (opens new window) for your platform.

    TIP

    If using the Chrome web browser, a simple cross-platform alternative is to install the configurator as an extension from here (opens new window).

  3. Connect the board to your PC and start the Configurator.
  4. Press the Load Firmware [Local] button Betaflight Configurator - Local Firmware
  5. Select the bootloader binary from the file system and then flash the board.

You should now be able to install PX4 firmware on the board.

# Bootloader Update using Source

# Download Bootloader Source

Flight controllers that have bootloader PX4-Autopilot make targets, can build the bootloader from the PX4-Autopilot source. The list of controllers for which this applies can be obtained by running the following make command, and noting the make targets that end in _bootloader

$make list_config_targets

...
cuav_nora_bootloader
cuav_x7pro_bootloader
cubepilot_cubeorange_bootloader
holybro_durandal-v1_bootloader
holybro_kakuteh7_bootloader
matek_h743-mini_bootloader
matek_h743-slim_bootloader
modalai_fc-v2_bootloader
mro_ctrl-zero-classic_bootloader
mro_ctrl-zero-h7_bootloader
mro_ctrl-zero-h7-oem_bootloader
mro_pixracerpro_bootloader
px4_fmu-v6u_bootloader
px4_fmu-v6x_bootloader

To build for these flight controllers, download and build the PX4-Autopilot source (opens new window), and then make the target using the following commands:

git clone --recursive  https://github.com/PX4/PX4-Autopilot.git
cd PX4-Autopilot
make <target> # For example: holybro_kakuteh7mini_bootloader

For other flight controllers download and build the Bootloader source (opens new window) and then make using the appropriate targets:

git clone --recursive  https://github.com/PX4/Bootloader.git
cd Bootloader
make <target> # For example: omnibusf4sd_bl or kakutef7_bl

# Flash Bootloader

You can flash the PX4 bootloader using the dfu-util (opens new window) or the graphical dfuse (opens new window) tool on windows.

Don't be afraid to try flashing using any of the methods below.

Note

The STM32 MCU cannot be bricked. DFU cannot be overwritten by flashing and will always allow you to install a new firmware, even if flashing fails.

# Enter DFU mode

Both methods require the board to be in DFU mode. To enter DFU mode, hold the boot button down while connecting the USB cable to your computer. The button can be released after the board is powered up.

# dfu-util

Note

The Holybro Kakute H7 v2 and mini flight controllers may require that you first run an additional command to erase flash parameters (in order to fix problems with parameter saving):

dfu-util -a 0 --dfuse-address:force:mass-erase:leave 0x08000000 -D  build/<target>/<target>.bin

The command may generate an error which can be ignored. Once completed, enter DFU mode again to complete the regular flashing.

To flash the bootloader onto the flight controller:

dfu-util -a 0 --dfuse-address 0x08000000 -D  build/<target>/<target>.bin

Reboot the flight controller and it let it boot without holding the boot button.

# dfuse

See the dfuse manual here: https://www.st.com/resource/en/user_manual/cd00155676.pdf

Flash the .bin file.

# Reinstall Betaflight

In order to switch back to Betaflight:

  • Backup the PX4 parameters, e.g. by exporting them to an SD card
  • Keep the bootloader button pressed while attaching the USB cable
  • Then flash Betaflight as usual with the Betaflight-configurator

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