How do I make a 58-key matrix that works with a Pro Micro?

[kelvinhall05]

I'm designing a PCB and although I'd like it to have more than 58 keys, I don't think that's gonna happen, at least with a Pro Micro (which I would rather use than spend like 6x as much on a Teensy, as well as redesign the work I've done in my schematic, which is attached). How can I wire a key matrix that will have all 58 keys? afaik I only have 8 lines available for both rows and columns, but mabye I'm missing something idk. The pins my guide said to use are PF0-PF7. Thanks!

Guide: https://github.com/ruiqimao/keyboard-pcb-guide
My schematic so far: https://imgur.com/a/03eTlz4

[purdobol]

I'm confused. You want to use Pro Micro as a daughter board or 32U4 chip integrated into pcb itself?

[kelvinhall05]

I'm confused. You want to use Pro Micro as a daughter board or 32U4 chip integrated into pcb itself?

I want to use the Pro Micro as a daughter board. As I understood it, the schematic symbol that I used *was* a Pro Micro. Is it not?

[purdobol]

No it is for the chip alone. Pro Micro has all the necessary stuff built in (like crystal, capacitors, resistors).
And has 18 pins available for use so up to 80 keys (10x8). So the only thing left is trace management and diodes.

[kelvinhall05]

No it is for the chip alone. Pro Micro has all the necessary stuff built in (like crystal, capacitors, resistors).
And has 18 pins available for use so up to 80 keys (10x8). So the only thing left is trace management and diodes.

OK. How would I do a schematic that uses a Pro Micro?

[purdobol]

Just ignore the "Schematic" part of the guide and follow the rest I guess.
When you get to the Routing paragraph, align the traces to correspond to the Pro Micro pinout.
wiki/Arduino_Pro_Micro.

Or maybe try handwiring method first. It'll be way easier, and it is great learning exercise.

[kelvinhall05]

Just ignore the "Schematic" part of the guide and follow the rest I guess.
When you get to the Routing paragraph, align the traces to correspond to the Pro Micro pinout.
wiki/Arduino_Pro_Micro.

Or maybe try handwiring method first. It'll be way easier, and it is great learning exercise.

OK, thanks. Can I make the matrix for 80 keys but have a few empty switch positions?

[purdobol]

Yes, provided you have the physical space for the switches.

[kelvinhall05]

Yes, provided you have the physical space for the switches.

Yeah, not quite sure how to put it but imagine a 60% PCB with no switches where the Windows keys go. That's kind of what I'm thinking.