i.e. the next step beyond Wikipedia? The things I'm interested in learning are ADC/DAC methods, as well as getting bits into and out of RAM memories. This will be for a digital building-block approach to short time delays as in this topic: http://www.diystompboxes.com/smfforum/index.php?topic=74254.0
There just seems to be an information gap between what the datasheets expect you to already know, and what resources like Wiki only generally hint at. So frustrating!
Introduction to digital logic and digital circuits is generally either one 5-hour lecture course or two sequential 3-hour lecture courses in the EE curriculum. That's with a live lecturer and probably 1-2 hours of lab work per week. There is no coursework which directly involves datasheet reading or use of complex logic blocks that I know of; it's mostly what you learn in your first couple of years as a junior EE. Intro to digital signal processing (ADC/DAC and so on) is probably another 3-5 hour lecture course.
I say that not to indicate that learning in a classroom setting is the only way to learn this, only as a yardstick for how much you're biting off if you want to really learn to design with this stuff. There is a certain minimum you're going to have to learn just to understand what the datasheets mean by the words, and yet more is needed to start splicing devices together. Reading and self study is a fine way to go about it, but you will lack the presence of a live tutor to tell you what you're missing and to check how well you understand what you THINK you understand. It tends to take longer that way.
Here's good first step - go get a copy of Lancaster's CMOS Cookbook and read all the design parts. That's the shortest, easiest to digest intro to digitial design I can think of. And it is only an intro, albeit a good one. It will at least let you know a more comprehensive set of questions.