beginner in need of guidance for first custom build (pcb question)

[hvns_lab]

hello,

i'm completely new to building keyboards and am a bit confused.  could anybody help me out?
i sketched out a rough idea of what i want to build, but the setup is a bit complicated in that i need this to have two separate arduinos and two separate usb outputs (purple keys=usb output 1, clear/grey keys + rotary=usb output2).  reason is that the purple keys will be controlling stream deck software on my iphone, and the clear/grey keys go to my computer.  i'm already running this setup with separate premade keypads but want to build a single centralized controller.  would this be possible with one single unified pcb?  also is there anything i would need to add to the pcb design for rotary encoder functionality?

[suicidal_orange]

Welcome to geekhack, this looks like an interesting project

A PCB is just a way of holding components and wires in place so there's nothing stopping you making two things on one board but routing the traces might be fun.  It would probably be easier if the Arduinos were on the other side (assuming the blue thing in the second pic is one)

As to what components you would need for a rotary encoder that would depend on the encoder so just find a tutorial and copy it.  It will probably tell you to poke wires in a breadboard but instead you would run traces, with gaps for any diodes/resistors/whatever.

Are you planning to get the PCB made or as it's relatively simple DIY it?

[hvns_lab]

Welcome to geekhack, this looks like an interesting project

A PCB is just a way of holding components and wires in place so there's nothing stopping you making two things on one board but routing the traces might be fun.  It would probably be easier if the Arduinos were on the other side (assuming the blue thing in the second pic is one)

As to what components you would need for a rotary encoder that would depend on the encoder so just find a tutorial and copy it.  It will probably tell you to poke wires in a breadboard but instead you would run traces, with gaps for any diodes/resistors/whatever.

Are you planning to get the PCB made or as it's relatively simple DIY it?

thank you so much for the reply!

concerning the arduinos, i was actually going to ask what best practices would be in terms of placement, by other side do you mean under the keys and on the bottom side of the pcb?  i kind of just roughly threw the arduino on the side because i liked the look of it on some keyboards i was referencing but that part i would definitely be willing to move around to make the traces easier.

i'm planning to try to design a pcb and order from pcbway or somewhere similiar, and to 3d print the case (or an acrylic sandwich case).  i haven't looked into DIYing a pcb though, would you recommend that route instead?  also i was doing some more research and am seeing that hand wiring might be an option, would that be better for a simple build like this?  (i was thinking about adding an led indicator for different rotary knob modes which might make things a bit more complicated)

[suicidal_orange]

For the Arduino placement if you put one either side of the switches at the top you could have both ports visible at the back to easily remove the cables and you wouldn't need to cross any traces so could get a PCB made.  If you put one as pictured and the other nearer the wrist rest you'll have to get the USB cable through the case, so that's going to be a big ugly hole.  Maybe you don't care though if it's facing a wall?  Or maybe you want to spend lots and get a port to attach to the case with a short cable to the Arduino?

Hand wiring would let you cross the traces (using insulated wire) so the Arduinos could go anywhere and it's cheaper than a custom PCB but you would need to accurately 3D print the plate to hold the switches and get a panel mount encoder.  LEDs again would need mounting, round ones can be pushed into tight holes easily enough but if you're thinking of a single RGB indicator that won't be round and you'll probably need a PCB.

DIY PCBs are rarely seen, the traces are easy enough to do but accurately drilling all the holes to put the switches through would be the fun part.

[hvns_lab]

ah yeah actually i didn't even consider the cable placement that's very true.  regarding crossing traces, would that mean that theoretically i could keep one arduino on the side as long as it was the one controlling the grey keys, and the second arduino on the bottom, under the purple keys, with the only weirdness being a bit of a gap between the two usb outputs?  feel like i could be ok with that given i quite like the look of the left side arduino.

[suicidal_orange]

You could put the Arduino under the switches but that means you can't get to them if you have a problem with your soldering or want to swap them for another switch, and it might be more confusing to design.

You've got me thinking though - if you had one Arduino above the PCB and the other under it in the same place would it be possible to solder only some pins to both in such a way that you get enough pin on each?  I guess that would depend which Arduino you had in mind but I think it would work as you only need 8 pins for purple and 7 + [rotary] for the grey.  Using a two layer PCB you could do any crossing traces on the other side using vias...