What the reason was for using (a snapshot of?) the twi.c internals from the Wire library instead of Wire? I'm suspecting some sort of incompatibility, but I'm not finding many clues in the history. Will it work on the GD32-based (?) Model 100 without porting to Wire? The Kaleidoscope hardware support for the Model 100 seems to use Wire to talk to the ATtinys, from what I can tell.