And I'm pretty sure it's not, although it might well be a side issue, the level shift is probably a good idea in prod cause 3.3v is really on the logical edge for an AVR running at 5v. I can confirm that I have received packets on the AVR! I wouldn't say it's up and running, but it seems to work. To be honest I'm not sure what I did. I cleaned up around the code. Part of the problem was me being an idiot and declaring the ports "absolute" binary values when the sbi/cbi method is used throughout.