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

At this point, the switching mechanism has already been fully developed and all components were in place, although only on a breadboard. As the project is rooted in the smart home milieu, the decision on a microcontroller was easy: An ESP12 module based on the famous ESP8266 chip by espressif is the heart of the application. As mentioned before, GUIs can be altered by simply changing bits from zero to one or vice versa. Altering objects of the physical world requires kinetic energy. Therefore an electromechanical transducer is necessary. After many experiments, the decision was finally made in favour of a 12V DC brushed gearmotor. To control it with a microcontroller the L9110S H-bridge driver IC has been chosen. As the ESP runs on 3.3V, a regulator IC (12V to 3.3V) was also to be installed as well as a couple of resistors, capacitors, and buttons.

Before going into detail about the actual layout or so-called floor planning, I would like to add a few sentences about the look. The new subject shifted the focus slightly to more technical/constructional aspects, which is why I felt the need to pay extra attention to the graphical appearance. Since the ESP module rises above the other components, it was clear that it would have to be given appropriate treatment. Thus, it will be duly honoured by the <i>Wifi Prayer</i> (see sketch below) on the final design. (Well, it won't fit entirely on the plain, but its praising hands.)

As the graphics are not on the silkscreen layer, but the areas have been exposed on the soldermask layer, I found an opportunity to combine artistic and technical peculiarities because it makes these excellent GND connections for crocodile clamps while debugging. [spoiler alert]

 

A milestone on the way to a PCB 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). Another major restriction was the form of the cover's connection clips. It was an eternal back and forth between different media (Paper, Fusion, KiCAD, soldering iron, and back again) before the hand-soldered prototype was finished.

It cost me some time and some burnt-out components but I was glad to have figured it all out before the PCB went into production, and when it finally did, all I could do was wait…. I purchased my first PCB ever at [https://aisler.net aisler.net]. Refreshing the order history every second at some point (a few days later) revealed the smart test results, which made me even more excited.

The prototypes shown in the picture above are only some of those I did. To be honest, I ordered another six PCBs right after receiving the first batch because in the meantime I already improved my design slightly. Also, I actually wanted to have a black solder mask, which is not available at aisler and that is why I ordered a third batch (again with some minor improvements) at [https://jlcpcb.com J@LC]. Luckily I realised the design as one layer only because there has been a special offer of aluminum PCBs and those do not support multi-layer designs.

 

 

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