Prototyping Electronics
Nov 2020 | By: David
Keyboards, in general, contain only a small number of major discrete electronic components: the microcontroller unit (MCU) and the key switches.
ok there are obviously more, but for the purpose of this, we'll keep it simple
Given this, we could either:
Fully custom design a printed circuit board (PCB) that incorporates both the MCU + key switches
OR
Custom design PCB to incorporate the key switches + incorporate an off-the-shelf (OTS) MCU board
To choose between these two options, we needed to consider:
Cost (development + per unit costs)
Time (development and sourcing)
We found that choosing an OTS MCU board was the best option moving forward. Surprisingly, the off-the-shelf MCU boards are generally cheaper than fabricating our custom PCBs. In addition to cost savings, we would not have to spend time setting up the PCB fabrication and assembly process. However, the disadvantage is that we would have to work around the OTS MCU board footprint (which was discussed in a previous blog post).
Because we chose an OTS board, we could quickly prototype and iterate with very little investment costs. We were essentially able to develop the entire stack (OTS MCU board + key switches + QMK firmware) independently of the casing. The only thing that interfaced between the electronics and the casing was the custom PCB that integrated the key switches with the OTS MCU board.
Due to these decisions, we were able to keep initial investment costs low while focusing more on the industrial design and user experience. In addition, we were able to simplify our supply chain significantly, which reduces risk and points of failure (something I will talk about in a future blog post!)