Arduino for STM32

it is possible to write directly to flash instead of using EEPROM emulation, these are mostly covered in the FLASH sections of the ref manuals.
The way flash works is that if a page is erased it is reset to 0xff for all bytes, writing data to them toggle the bits to 0.
Hence, it may be possible to ...

Well despite all that tariff turmoil, I spotted this STM32H503 board from WeAct
https://github.com/WeActStudio/WeActStudio.STM32H503CoreBoard
https://www.aliexpress.com/item/1005008391813630.html

this board is practically a replacement for the stm32f401/411 black pill boards with a STM32H503CBU6 ...

you need to mention the core and the board that you used
https://github.com/stm32duino/Arduino_Core_STM32/wiki
https://www.stm32duino.com/viewtopic.php?t=3
https://www.stm32duino.com/viewtopic.php?t=301

and normally, simply taking codes from github may not run out of the box
e.g. that you may need ...

I'd guess reviewing the datasheets would be a best option.

A thing I tend to note about stm32 mcus is that for the 'lower ports' e.g. PAxx and possibly PBxx as well, stm32 tends to keep the definitions 'the same'.
I'd guess that in part so that firmware built for a particular mcu could 'just works ...

oscar,
I've done a lot and lot of tests without any signigicant progress, but i'm using a tft display to get the debug messages so I've to clean the code to post it here to let someone (like you've been doing) can keep an eye of it. Something very wrong i'm doing that something almost simple as ...

to debug in cubeIDE, make a project and copy the codes there, you would need to copy the core there too and make sure that the paths are all setup correctly so that it'd build.

one way to do that is to use CMake
https://www.stm32duino.com/viewtopic.php?t=2563
https://github.com/stm32duino/Arduino ...

well, I'll start investigating about DMA and Timer combination, maybe with gpt help to speed it up, given that never looked into dma stuff, hardly imagine what it is, but need to figure out exacly how it works, how to configure a timer to start reading a buffer and increment its index, the way and ...

if things are actually working, after you flash/upload the firmware, you need to press reset to restart the board.

otherwise
----
if you want to use maple bootloader, you may need to install and configure the other core Arduino_STM32
https://github.com/rogerclarkmelbourne/Arduino_STM32/wiki ...

I think it is related to the 'upload method', if you choose st-link or uart install (requires setting boot0), it'd compile the firmware for the start of flash, and that'd normally overwrite the bootloader if your 'upload method' is st-link or uart.

try using CMake
https://github.com/stm32duino/Arduino_Core_STM32/wiki/CMake-presentation
https://www.stm32duino.com/viewtopic.php?t=2563

it may help.
that is especially true after an initial build. CMake and make recompile only changed files by checking the date modified.
so if you need to rebuild ...