If you ever had to communicate design in the context of agile software development, I recommend you take a look at C4 diagrams from Simon Brown. Lean, ,quick method to create design diagrams. I've been working on a plantuml (text base diagrams) implementation of the C4 diagrams. Just finished the first 2 core diagrams: https://bitbucket.org/benoitjoly/plantuml-c4-macros/

Here is the final result of my preonic build. Time to customize the firmware.