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The code for the PX4 bootloader is available from the Github Bootloader repository.
- FMUv2 (Pixhawk 1, STM32F4)
- FMUv3 (Pixhawk 2, STM32F4)
- FMUv4 (Pixracer 3 and Pixhawk 3 Pro, STM32F4)
- FMUv5 (Pixhawk 4, STM32F7)
- TAPv1 (TBA, STM32F4)
- ASCv1 (TBA, STM32F4)
Building the Bootloader
git clone https://github.com/PX4/Bootloader.git cd Bootloader git submodule init git submodule update make
After this step a range of elf files for all supported boards are present in the Bootloader directory.
Flashing the Bootloader
The right power sequence is critical for some boards to allow JTAG / SWD access. Follow these steps exactly as described.
The instructions below are valid for a Blackmagic / Dronecode probe. Other JTAG probes will need different but similar steps. Developers attempting to flash the bootloader should have the required knowledge. If you do not know how to do this you probably should reconsider if you really need to change anything about the bootloader.
The sequence is
- Disconnect the JTAG cable
- Connect the USB power cable
- Connect the JTAG cable
Black Magic / Dronecode Probe
Using the right serial port
- On LINUX:
- On MAC OS: Make sure to use the cu.xxx port, not the tty.xxx port:
tar ext /dev/tty.usbmodemDDEasdf
arm-none-eabi-gdb (gdb) tar ext /dev/serial/by-id/usb-Black_Sphere_XXX-if00 (gdb) mon swdp_scan (gdb) attach 1 (gdb) mon option erase (gdb) mon erase_mass (gdb) load tapv1_bl.elf ... Transfer rate: 17 KB/sec, 828 bytes/write. (gdb) kill
These instructions are for the J-Link GDB server.
Download the J-Link software from the Segger website and install it according to their instructions.
Run the JLink GDB server
The command below is used to run the server for flight controllers that use the STM32F427VI SoC:
JLinkGDBServer -select USB=0 -device STM32F427VI -if SWD-DP -speed 20000
--device/SoC for common targets is:
- FMUv2, FMUv3, FMUv4, aerofc-v1, mindpx-v2: STM32F427VI
- px4_fmu-v4pro: STM32F469II
- px4_fmu-v5: STM32F765II
- crazyflie: STM32F405RG
arm-none-eabi-gdb (gdb) tar ext :2331 (gdb) load aerofcv1_bl.elf
If any of the commands above are not found, you are either not using a Blackmagic probe or its software is outdated. Upgrade the on-probe software first.
If this error message occurs:
Error erasing flash with vFlashErase packet
Disconnect the target (while leaving JTAG connected) and run
mon tpwr disable swdp_scan attach 1 load tapv1_bl.elf
This will disable target powering and attempt another flash cycle.