There’s no getting away from the fact that you have to understand a bunch of acronyms in order to understand how BLE works.
I see that the Bluetooth Specification Version 4.0 is now available to everyone. When I first looked for 4.0, you had to be a Bluetooth member.
It’s quite well written for a standards document. It is 2300+ pages so I won’t be sending a request to the Xerox subdivision – well not yet anyway. A lot of it is at a level I don’t understand or care much about.
Here’s what I think is worth taking a closer look at:
Vol 1, Part A, and B seem like good general background reading.
Vol 3, Parts F, G and maybe H are probably useful
Vol 6, which is all about BLE, actually doesn’t seem all that useful at this stage.