@User: I will try to document the I/O as well as I can, when we get the libraries in the repository. There are a huge number of rings, as you noted. There are 1.8V power and ground, 3.3V power and ground, 3.3V ESD power and ground, two analog signal buses, a hibernation keep-alive power bus, a switching supply for the analog multiplexer, and some of those are repeated. It is wildly over-designed. I am hopeful that someone can take the essential subcircuits from the library (clamp circuits, ESD diodes, level shifters, etc.) and create a simpler set of pads. But pad design is quite tricky.