Beginners Question - Why arduino?

Excuse the potentially stupid question, but I’m trying to take a step back and really consider what tools I use for my next project, rather than diving straight in.

I have a field, and I’m working on a few ideas in C++ (various physical modelling implementations, maybe some vector synthesis, and an idea for a buchla 296e inspired filterbank). Eventually I would like to move towards more custom hardware with daisy as the backbone (I’d like to be able to build more CV or audio i/o, perhaps more knobs, maybe for eurorack, maybe as a standalone desktop box as part of my live rig).

I am wondering specifically about the practicalities of running the daisy with arduino? What are the benefits of building a daisy based system with an arduino? Is running the Daisy with arduino mutually exclusive to deploying C++ code onto daisy?

Just trying to weigh up the potential benefits of an additional hardware board (and whether it should be an arduino, or something else). I had an idea of running an arduino as a kind of signal processor before the daisy, allowing the arduino to take in CV or midi signals, manipulate them as appropriate and feed them into the daisy (via GPIO? replacing then the field with my own frankenstein inputs and controls).

Any thoughts or recommendations for learning more would be warmly and gratefully accepted!

Arduino is useful as a learning tool for newbies, other than that it would create more problems that it would solve. You typically won’t see such approach (using Arduino as IO expander) in commercial projects. There are dedicated chips for adding more GPIO or CV inputs that don’t require separate firmware, are cheaper and take less space.

Daisy hardware doesn’t care about such things, you would be using something like SPI/I2C/UART to exchange data and it doesn’t matter for it what’s on the other end. You certainly shouldn’t be using GPIO for this, if you think that GPIO is appropriate you might want to spend some time reading about hardware peripherals available on STM32H7 MCU.