GMU:Printed Circuit Board Art/mxkllmnn: Difference between revisions

The design was very much influenced by the early thoughts on the topic of "capacitive touch". I would have installed all the technical components in a [https://www.instructables.com/Dead-Bug-Prototyping-and-Freeform-Electronics/ dead bug] fashion, disappearing into the flush socket of the wall, if it hadn't been for the idea of realising the entire backend as a PCB in the front, with touchpads on its rear. However, when the idea of touch input gestures was dropped (because this contrasted with highlighting mechanical devices), all that was left were components that logically belong to the backend. Yet, having everything fit tightly into the cover of the switch makes debugging very easy. By removing it, all the connections are accessible. So the transfer from breadboard to a PCB was the only logical consequence. To achieve this, several steps had to be taken.  

A milestone on this way is a hand-soldered prototype. As common switches come with a cover, the base plate already existed. But I did not start soldering right away. The first thing I did was a rough sketch of all components and their respective connections on a piece of paper. Only then I made my first attempts at this design in KiCAD. Since I did not want to spoil my option of revisiting capacitive touch gestures at a later stage, it was my personal challenge to realise everything on just one side of a PCB with no viases or through-hole components. Of course, this also meant that all elements had to be placed so that there is no intersection of a single trace, which has been hard before I got to know the practice of ground areas (across the entire PCB). Before the final layout was finished, it was an eternal back and forth between different media (KiCAD, paper, Fusion, soldering iron, and back again).  

Still, this process was necessary to eliminate all the flaws of my design iteration by iteration, first and foremost an issue referred to as decoupling [http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html] [http://www.lothar-miller.de/s9y/categories/14-Entkopplung]. This is of particular importance in my application as the ESP module is quite sensitive to noise and one of the worst components one can think of in terms of noise are motors. Here we have them combined on a tiny space of 50x50mm.