How to flash STM32 PlatformIO firmware using dfu-util

First, you need to find the correct firmware file. dfu-util will flash firmware.bin, not firmware.elf. You can find firmware.bin in

.pio/build/[PROFILE_NAME]/firmware.bin

inside your project folder. [PROFILE_NAME] is the name of the build profile you’re using, i.e. the name of the section in platformio.ini. For example:

.pio/build/BIGTREE_OCTOPUS_V1/firmware.bin

Now flash using dfu-util:

dfu-util -a 0 -D .pio/build/PROFILE_NAME/firmware.bin -s 0x08000000

Flags:

• -a 0. The STM32 appears as four different devices in dfu-util (see dfu-util --list): The flash, option bytes, RAM etc each appear as a separate device. We only care about the flash device, which is always the first (index 0) of those devices, at least in every board I have seen so far
• -D [filename]: Download the firmware to the device
• -s 0x08000000: Flash at address 0x08000000 which is the address of the STM32 flash.