TIL C++ has exception for main function to be without return even though they forced it to have int return type. Can someone explain to me why this was done? C was happy with void return type but C++ forces int, yet implicitly adds return 0 if missing.
Try look for local FabLab or Maker/Hacker Space. People in there are usually willing to share their knowledge or they are even organizing some courses on that topic.
Either way, it's mandatory to understand electronics essentials (Ohm's law, Kirhoff's laws etc.) Try to find some electronics schoolbooks (I can provide something in czech only). After understanding basics, you can start with buses and digital communications (because digital is actually two level analog, right?)