I've been using the mega324p in WINAVR 20100110. I've changed to the mega324pa, I believe the devices are compatible but I've changed the processor type in the make file to mega324pa. The register definitions are now different so I can't compile. The first I've noticed is that the SPI registers all need to have a trailing 0, ie SPDR becomed SPDR0. Is there a reason for this as it now does not tie up with the Atmel datasheet for the mega 324pa?