[avr-libc-dev] Re: [bug #18818] ATMega644P missing second USART erroneously

[Joerg Wunsch]

As Tero Sinervo wrote:

> What happened was I never bothered to check if it really works,
> fooled by the absence of 'p' in the individual header files, coupled
> with this line in iomxx4.h:

> /*
>  * Only ATmega164/324 have a second USART.
>  */

OK, I fixed that.

Historical note on this is, the initial ATmega644 datasheet covered
the variants called ATmega164 and ATmega324 as well, and unlike the
'644, these devices already featured the second USART.  While the
ATmega644 has then been produced as described there, the 164/324
version never materialized, and instead became what is now known as
ATmega164P/324P.  During the course of that change, they eventually
got accompanied by an ATmega644P enjoying the same feature set as its
smaller brethren, and thus probably being the only picopower variant
that has a different feature set than the respective non-picopower
devices.

Our header file has been written according to the original intention
(based on an early preliminary datasheet), and while it got updated
for the picopower devices later on, it seems this comment has never
been changed.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)