Starting a project that's slightly beyond one's comfort zone is the best method of advancing your skills. And if you blog about it on top, the payoff is even larger.
We're guessing that's what the author iAchieved.it blog did in his two part exhaustive tutorial on building a Loop calibrator using BeagleBone with click boards, with a mikroBUS cape in between.
In the age of dwindling attention spans, it's a true gem to find a tutorial of this scope. Even if you don't want to build a 705 Loop Calibrator, we encourage you to at least skim through these posts, as you might find some tricks and tips that can come in handy -- some of the topics are universal, like the treatment of SPI.
if you're into detailed and thorough tutorials such as this one, you should definitely check out the writing on Embedded-Lab.