[avr-gcc-list] Atmega 329

[Björn Haase]

Message: 8
Date: Wed, 20 Apr 2005 21:46:30 +1000
From: "Ron" <address@hidden>
Subject: [avr-gcc-list] Mega329
To: <address@hidden>
Message-ID: <address@hidden>
Content-Type: text/plain; charset="us-ascii"

>I want to replace the Mega169 currently in use in a product with the
>Mega329. Atmel had said (through their Australian agents) that the '329
>is a direct replacement. After plugging one in I found the pin change
>interrupt I use on PE2 was not working. After much searching I found a
>small note on page 47 of the '329 manual saying the PCINT2 was not
>implemented on the '329. This was duly reported to Atmel that it really
>was not a plug-in replacement for the '169. Their reply was I should
>specify the '329 to the compiler (rather than the '169), and give them a
>call when I had tried this.

I don't know the exact details. As much as I know, the series 169-329 and 649 
were supposed to be "almost" compatible in the sense that Atmel said that 
possibly the bit distribution whithin the registers and the addresses of the 
register numbering possibly itself is subject to change. E.g. a register 
named ADSRA would be supposed to exist on both controllers, but might end up 
at a different position in the address space and a bit named AEN might once 
happen to be bit #7 and once bit#6. I have no idea, whether atmel actualy 
*did* implement such a change.

I think the best thing to do would be to ask ATMEL to send you an explicit 
changes list (or possibly you could do a diff on the io-header files that 
atmel provides for the mega169 and the 329 to find out the differences).
Once you are having the header files adapted, I think that it will be fairly 
straight-forward to include support for the atmega329 in avr-libc. I'd be 
willing to help to get a -mmcu=atmega329 into gcc as well.

>Problem is, avr-gcc doesn't support or include an iom329.h file yet, and
>even if it did, I can't see how this would compensate for the missing
>PCINT2.
If indeed there is no longer support for this HW function, no new set of 
header files will be helping you :-(. In the worst case, you will have to 
change the hardware.

>Maybe I'm missing something here. Has anyone else had this problem? If
>the team is looking at supporting the '329 with avr-gcc, could they have
>a look at this apparent discrepancy?

>Cheers
>Ron Kreymborg
Yours,

Björn Haase