Easiest way to obtain a list of all STM32F446 hardware registers?

What do you want to do with that list once you have it? Without knowing that, it is hard to be more helpful.

If you run your C preprocessor on source-code that #includes <stm32f446xx.h> or whatever, that will combine all the appropriate h files into one huge file.

How do you do that? It depends on your development environment. On my preferred Rowley Crossworks, I right-click on the c file and select "Open With:Show Preprocessor Output"

Hope this helps,

Danish

Thank you