CODEWITHSUNDEEP
embeddedelfsconsstm32f4platformio
arkap
arkap

Reputation: 37

PlatformIO: Best way to combine Bootloader and Application Images

I am working with two distinct Platformio projects for an stm32f4 target: a bootloader and an application. Eventually, the bootloader should be able to update the application code over the network but for now I want to structure the build system such that I can conveniently flash the chip using a programmer for development. I was able to get the two parts to execute correctly by creating separate .elf images and flashing the application image followed by the bootloader image manually using OpenOCD. However, it would only run if I flashed the application first and then manually erased and wrote the bootloader sector using OpenOCD's flash erase_sector and flash write_image commands.

My goal is to have a flexible setup that allows me to flash the MCU conveniently and to generate separate binaries in the future when updates over the network come into play.

I have some ideas about how to proceed but I am unsure what the best way forward is:

a) keep building separate images and look into objcopy/objdump to slice and merge .elf files to be able to create a combined image which should be easy to upload onto the target MCU, or

b) work with scripting PlatformIO such that I link a combined image from object files in the two projects' .pio/build directories.

I was also wondering whether I could work within the PlatformIO frame instead of scripting around two entirely separate projects.

Any input is appreciated.

Upvotes: 0

Views: 113

Answers (1)

arkap
arkap

Reputation: 37

I've figured out a way that works with PlatformIO and is convenient:

  1. Keep the projects separated with their own linker scripts but make sure they get linked into disjoint areas of flash memory.
  2. Convert the .elf files created by PlatformIO to .bin files using arm-none-eabi-objcopy -O binary (I've included this as a post action with PlatformIO).
  3. Flash using a script that invokes openocd. The important part here is to upload the images as binary and not as .elf. This requires providing the addresses in flash:
openocd <target-specifics copied from Platformio> --command 'program { <path/to/bootloader.bin> 0x08000000 verify' --command 'program {path/to/app.bin} 0x08020000 verify' --command reset --command shutdown

This preserves debug symbols and works with the debugger in VSCode.

Upvotes: 1

Related Questions