AVR-Chat

On Sun, 6 Dec 2009, Jim Wagner wrote:

>> #define UCSRC   _SFR_IO8(0x20)
>> #define UBRRH   _SFR_IO8(0x20)
> If I recall correctly, those two DO share the address and require a
> data bit to distinguish which is which. It is NOT a compiler error.

Thanks for your input, Jim.

I originally used the USART C code from the data sheet,
which worked fine with ATtiny2313.

The C code in the data sheet for the ATmega8 is identical,
and as such I'd expect the program to port cleanly between
these microcontrollers by simply specifying a different
-mmcu flag.

Strangely, the code didn't work on atmega8 as soon as I
specified -mmcu=atmega8, but it did when I specifield
-mmcu=attiny2313.

After the changes that I outlined in my previous post,
the code ports and works transparantly on either uC, as
I would have expected.

If the ATmega8 would need setting a data bit to
distinguish between UCSRC and UBRRH, then my proposed
change to the header file would not have made it work;
this evidence suggests that there was, in fact, a bug
in the mentioned header file.

As the ATmega8 *does* send data through the USART now,
I wonder if I'm overlooking something trivial?

Best,
Marc