[stavros]

This is fantastic. You've detailed a lot of the stuff that ruined my projects, though I never really actually sat down to learn about parasitic inductance and how to combat it. Now I look at the datasheet and make sure I don't miss any of the recommended caps and resistors, though I'm still not at your level of complicated design.

The finished product looks great, well done! By the way, why not add two more buttons at those two blank corners? Is it because the labels wouldn't fit on the display? You could always replicate the layout onto the display itself and put the labels on that.

[cmpx]

Thanks!

About the buttons in the corners, I wish we could use that space too! :) Most of the electronic components (MCU, power supply circuit) are located in the corners, while the remaining PCB area is occupied by the mechanical switches, display/battery, and the encoder.

[stavros]

Ahh, I see. Wouldn't it work to put those on the underside?

[cmpx]

Great idea! Actually the mk3 of the PCB had these parts on the bottom. The reason for putting them on the top layer was that this way we can decrease the thickness of the macropad (we don't need much space between the pcb and the backplate). For now it is basically a tradeoff. One way of improvement could be, that we don't use a BLE module, but solder the MCU directly to the PCB and use smaller passive components. This way the max. height of the components could be decreased and we could put them back on the bottom. This would also mean I have to design the RF parts, which is very far outside of my knowledge.

[stavros]

Hm yeah, there isn't really much space for the module, huh. One idea would be to cut the PCB and use castellated edges to solder the module to, which will make it thinner by one PCB height, but it'll be tricky.

Plus, it looks like your module has multiple rows of pads, but I'm not sure about that.