This is what I've got so far:
SPIF -> TXC0 // TRansmit complete flag
SPDR -> UDR0 // Data register
But I'm confused about TXC0. It is a flag, and SPIF is a flag, but SPIF is a bit in register SPSR. I can't figure out if TXC0 is a bit in some register.
I also am wondering if it is necessary to do this:
while(!(SPSR & (1 << SPIF)));
Or if it is possible to just access SPIF directly like how is seems TXC0 is supposed to be used.
My gut tells me SPIF is just a bit number seeing how it is used there, but is TXC0 also a bit number? And if so in what register? I have no clue.