in here.

Notes about the PCB: This is a very typical "Kitchen Sink" project where it is easier to put a limited number of jumper wires on play rather than use a multilayer board. If this would go into serial production then ofcourse this board had to be redesigned. It is very expensive to use wires on board - especially if their lenght varies a lot. Don't do this at work !

I also chose to use a mica capacitor with low drift resistors to set up the MCU clock. That capacitor would cost almost triple that of a consumer grade chrystal. In addition the frequency stability is inferior. The only advantage here is the availablity in my garage (4K pieces of those) and the fact that I am all too used to make it this way. This might also start running earlier than the chrystal version.