That’s a great article! That someone would spend enough time to custom design this many PCBs and document the things they found is great!
It’s clear that the author came at this from a hobby or junior engineer perspective rather than a “we are going to make a million of these” perspective, though. The comments about DDR3 routing being easy, partial understanding of some of the errata and differences between revisions of silicon, comparing things by Digi-Key pricing, and lack of willingness (and I’m sure time) to investigate the nuances of some of the chips shows though. But still a very impressive piece.
It’s unfortunate that there’s not better examples of how to really leverage the TI PRU cores. They’re supremely powerful and can even replace the need for some FPGA implementations, that you can get them in such a cheap chip that also runs Linux is just great. Plus, each iteration of the TI AM-series SoC mostly keep backwards compatibility as the PRU abilities increase (AM18xx->AM335x->AM437x->AM57xx->etc all have PRU and the core concepts of how they work are very similar but the abilities and instruction set does evolve over generations).