Book "Building a Home Security System with BeagleBone" by Bill Pretty is freely avalaible today at publisher site: https://www.packtpub.com/free-learning. You need to claim it today and you get access to it forever. I have not read it, but written reviews on Amazon are quite positive. There are few negative ratings, but reviewers did not write textual review, so it is not clear what's wrong with book (if any). It is about 11 years old, but still may be interesting because electronics does not date so quickly (in comparison with computer science, for example). In comparison with other paid books, it is not that long (120 pgs).
