Delighted to see this tidy summary! I've been wading through four or five documentation sources over the past few days getting everything hooked up. I'm working on a project that uses SPI and would love to use Rust... I may pick your brains further.

Strongly recommend you post a link to this at the PADI Stamp forums, I'm sure others will appreciate it. http://forum.pine64.org/forumdisplay.php?fid=57