AVR-Chat

Hey guys,

I'm using the ATMEGA 103L and was wondering what the scoop is with 
memory mapped I/O registers?

Are there any caveats to loading and storing to and from these I/O 
registers via their memory-mapped address as opposed to using the in 
and out instructions?

Thanks

--- In AVR-Chat@yahoogroups.com, "europaphi" <europaphi@y...> wrote:
> Hey guys,
> 
> I'm using the ATMEGA 103L and was wondering what 
> the scoop is with memory mapped I/O registers?
> 
> Are there any caveats to loading and storing to 
> and from these I/O registers via their memory-
> mapped address as opposed to using the in and 
> out instructions?

Not that I've got experience SPECIFICALLY with the
AVR line, but in my experience they act pretty much
the same.  You can actually make your own memory
mapped I/O.  I've thought about doing it before.

For instance, you could use 32k of external RAM
and then use a latches and buffers to add extra 
input and output.  The whole I/O subsystem would
be activated (and the memory chip deselected) with 
bit 15 of the address.  It sounds a lot more 
complicated than it is. :)