I am a software engineer who is new(er) to electronics, I only started a couple of months ago. I've built a bunch of custom circuits, then some arduino nodes that are around my apartment that communicate with a C# server. So I've at least got the breadboarding part down.
So now I am working on a controller board that connects to my home automation system and determines the color on the LED light strips I installed into my bookshelf. So I want to transfer from working with pre-built Arduinos to building my own full node, there are some things I think I'm missing.
I've noticed that there are duplicate parts on the schematic for the Arduino Mega2560 schematic (such as there being 2 voltage regulators - one is replacement if the other is not available). I couldn't find any such description however for why there are 3 crystals located on the board. I see 3 different circuits for crystals (all of which are 16MHz).