> As for the electrical engineering, is the one with most pitfalls and the most expensive. A wrong voltage will release the magical smoke and is another 30$ for a board. Tread carefully.

I enjoyed reading "Exploring Beaglebone" by Derek Molloy a few years ago, because the book has sections "how to destroy your beaglebone" and "how to interface with electronics". The website seems broken. The book's ISBN is 978-1-118-93512-5. Some of the recommendations there (voltage clamping circuit on the 1.8 V analog inputs) can save your board.