The breakage of my other board has me obsessed — how could it be? Well, it could be for a simple reason: I had rebrained that board, and I had a bad solder joint on my replaced chip. That board had a damaged processor and I had decided to try my hand at replacing the CPU (and with a tastier one, the 415), which I did successfully much to my amazement. But I failed to consider that little fact about it’s history when I started this project, and also that I had not done a full test of it’s functionality. My fear was that I had broken a trace under the CPU but at length it simply turned out to be a bad solder joint, which was easily remedied with a smidge of molten lead, and the world seems sane once again. Anyway, lesson learned, and that board will not be used for further work on this project.
Eventually, I also discovered that I had a typo in the pin defs for the SPI ports in board.h. It was a cut-and-paste error, and I had copied the SPI1 text down into SPI2 and SPI3. I correctly modified the pin variant, but not the port number. I changed that and… it works! Or at least I can mount, and I can do a directory listing. Haven’t tried anything fancier, but that satisfies me at this phase.