add Holybro KakuteH7 support

[bkueng]

known issues:

• flash-based params does not work on H7 (due to ECC), so params are on SD card. The last flash sector is still reserved however.
• output channel 6 does not support DShot (the implementation does not handle channel gaps) Fixed in dshot: remove BOARD_DSHOT_MOTOR_ASSIGNMENT & handle timer channel gaps #19030
• flashing of the 2. flash bank is much slower (around 3x), than the 1. bank for some unknown reason. Fixed
• after the BL jumps to the app, there's several seconds passing until stm32_boardinitialize() is called.

[dagar]

flash-based params does not work on H7 (due to ECC), so params are on SD card. The last flash sector is still reserved however.

FYI I've been considering moving flash based parameters to littlefs as well (#18958).
The backing RAM for the erase sector is kind of expensive, but seems to scale well enough for each architecture (eg 128K H7, 32K F7, etc). If anything the hard part will be handling the transition.

[bkueng]

Does it work with a single page as well?

[dagar]

Does it work with a single page as well?

I still have to work through how to use the H7 flash (ECC, etc), but at the moment I don't see why it won't work with a single flash sector. There's a bit of a hole to be aware of when the entire flash sector needs to be erased (consider with wearleveling), but I think we can either live with it or use another flash sector as a backup (where necessary).

[mrpollo]

@bkueng which bootloader target did you use for the KakuteH7?

cc @vincentpoont2

[bkueng]

make holybro_kakuteh7_bootloader

[vincentpoont2]

@bkueng Sorry, how can I build the bootloader HEX file like this one , with make holybro_kakuteh7_bootloader, I only get the .bin & .px bootloader files.

[bkueng]

You can use arm-none-eabi-objcopy -Oihex file.elf file.hex to convert the file. We can add that to the build if you like.

[vincentpoont2]

You can use arm-none-eabi-objcopy -Oihex file.elf file.hex to convert the file. We can add that to the build if you like.

@bkueng Any chance you can share the bootloader HEX file directly so I can included in a kakute H7 PX4 doc?