[avr-libc-dev] atmega324 variants (P, A, PA) signature

[rr]

Hi!
I've chosen the ATmega324P to one of my projects and now that I'm 
testing some firmware in it, I have some doubts, which I could not clear 
up after doing some research on google and forums.
First datasheet I got was mega324P/V with signature bytes: 0x1e9508.
Then, the next datasheet was mega32pa with signature bytes: 0x1E9508.
Actual datasheet is mega324a/mega324pa. Here the signature bytes are 
different: mega324a: 0x1E9515 and mega324pa:0x1e9511.
Automotive version is mega324p-a with signature: 0x1e9508.

Aren't mega324a and mega324pa identical apart from some electrical and 
power consumption characteristics?

In avr-libc v1.7.0, there are 2 files:
iom324.h - for the  mega324p with signature 0x1e9508
iom324pa.h - for the mega324pa with signature 0x1e9511

I've searched for avr-libc manual on web and on pdf, but they are from 
2009 and of course are a little bit outdated. There is only mentioned 
the mega324p.

So, can I assume there is no support for mega324a, since there is no 
signature compatibility?

Where can I get a summarized information about the differences between 
mega324p and mega324pa other than looking throughout the datasheet?

Isn't Atmel confusing this part number thing a little bit?


Thank you.