Hello!
I'm using the F769. The reason is that I'm not very experienced with STM32, and I had no idea of the final
program size, etc. So I took a powerful beast that can be soldered by hand (i.e QFP, not BGA), the 208 pins
model. Quite a big stone. It's incredibly powerful. I also verified that I can get 16 microphones at once, it
works fine, and I can work continuously (i.e. not bursts). By the way, I was writing "180 MHz", but it's the
frequency of the F4x (I made the very first experiments with a F469 disco, the one with a nice LCD).
The F7x series can run at 216 MHz. You should be able to find a close frequency that would match with 22.5.
By the way, I don't know exactly what you are doing and neither how to do it, but here is a little advice.
At first, I thought that the code provided by ST is not very well written and I thought I would do it on my own,
as I'm used to do. However, I found out that using CubeMX can generate most of the code I need. For
example, what I was describing with my 16 mems mics can be generated (about 95%). The 5% remaining
consist in adding the interrupt routines, filling blanks, defining your own variables, etc. No headache fore
clock configuration, no danger of using a pin which is already use for another peripheral, CubeMX tells you
what is already used and what is not.
On top of that, you can also modify your program graphically in CubeMX, generate the new code again,
but CubeMX doesn't erase your code additions provided it's done in the proper areas. Example, you have
a working program. You want to add an SPI flash? Just click the checkbox in CubeMX, re generate, and you're
done. Your program still works the SPI for your flash is initialized, you just have to write the access functions.
Have fun!
Dora.