Dr. Andrew Veronis, Advanced Micro Circuits and Donald Jackson, Labcenter Electronics North America has created a reference materials called "A User's Guide to chipKIT and Pmods". It includes eight chapters including "What is microcontroller, Programming and so on. Each chapter covers theories, examples and hands on projects. It is free downloaded at https://docs.google.com/file/d/0B-oA-HSAnFDnVzAzeVVzOUFoRGs/edit?usp=sharing