# PX4 Bootloader Flashing onto Betaflight Systems

This page documents how to flash the PX4 bootloader onto boards that are already flashed with Betaflight (e.g. [OmnibusF4 SD](../flight_controller/omnibus_f4_sd.md) or [Kakute F7](../flight_controller/kakutef7.md)).

There are three tools that can be used to flash the PX4 bootloader: _Betaflight Configurator_, [dfu-util](https://dfu-util.sourceforge.net/) command line tool, or the graphical [dfuse](https://www.st.com/en/development-tools/stsw-stm32080.html) (Windows only).

:::info
The _Betaflight Configurator_ is easiest, but newer versions may not support non-betaflight bootloader update.
You might try it first, but use the other methods if firmware update does not work.
:::

## Betaflight Configurator Bootloader Update

:::info
_Betaflight Configurator_ may not support PX4 Bootloader update, as of May 2023.
Older versions should work, though the precise versions are not known.
:::

To install the PX4 bootloader using the _Betaflight Configurator_:

1. Download or build [bootloader firmware](#bootloader-firmware) for the board you want to flash.

2. Download the [Betaflight Configurator](https://github.com/betaflight/betaflight-configurator/releases) 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](https://chromewebstore.google.com/detail/betaflight-configurator/kdaghagfopacdngbohiknlhcocjccjao?pli=1).

:::

3. 将飞控板连接到 PC 并启动 Betaflight 配置器。

4. Press the **Load Firmware [Local]** button
   ![Betaflight Configurator - Local Firmware](../../assets/flight_controller/omnibus_f4_sd/betaflight_configurator.jpg)

5. 从文件系统中选择 bootloader 二进制文件，然后烧写进飞控板的 flash。

现在，您应当可以在飞控板上安装 PX4 固件了。

## DFU Bootloader Update

This section explains how to flash the PX4 bootloader using the [dfu-util](https://dfu-util.sourceforge.net/) or the graphical [dfuse](https://www.st.com/en/development-tools/stsw-stm32080.html) tool (Windows only).

You will first need to download or build [bootloader firmware](#bootloader-firmware) for the board you want to flash (below, this is referred to as `<target.bin>`).

:::info
All of the methods below are safe as the STM32 MCU cannot be bricked!
DFU 不会被烧写覆盖，并且总是允许安装新固件，即便烧写失败。
:::

### DFU mode

Both tools require the board to be in DFU mode.
要进入 DFU 模式， 当将 USB 连接到电脑时按住启动按钮。
The button can be released after the board has powered up.

### dfu-util

:::info
The [Holybro Kakute H7 v2](../flight_controller/kakuteh7v2.md), [Holybro Kakute H7](../flight_controller/kakuteh7.md) and [mini](../flight_controller/kakuteh7mini.md) 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 0x08000000:force:mass-erase:leave -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
```

重新启动飞控板，并且不要按下启动按钮。

### dfuse

The dfuse manual can be found here: https://www.st.com/resource/en/user_manual/cd00155676.pdf

Use the tool to flash the `<target>.bin` file.

## Bootloader Firmware

The tools above flash pre-built bootloader firmware.
Bootloader firmware can be built for most targets using the normal PX4 source code, while other targets can only be build using source in the bootloader repository.

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
holybro_kakuteh7v2_bootloader
holybro_kakuteh7mini_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](https://github.com/PX4/PX4-Autopilot), and then make the target using the following commands:

```sh
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 the [PX4/Bootloader](https://github.com/PX4/PX4-Bootloader) repository and build the source code using the appropriate targets:

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

## 重新安装 Beatflight 固件

In order to switch back to _Betaflight_:

1. Backup the PX4 parameters.
   You can do this by [exporting](../advanced/parameters_and_configurations.md#exporting-and-loading-parameters) them to an SD card.
2. Keep the **bootloader** button pressed while attaching the USB cable
3. Flash _Betaflight_ as usual with the _Betaflight-configurator_