Re: [avr-gcc-list] Non initialized data in EEPROM

[dimax un]

On 12/6/06, Ned Konz <address@hidden> wrote:
> dimax un wrote:
>
> > I have an array and some config data in eeprom
> >
> > char config_data __attribute__ ((section (".eeprom"))) = 5;
> > char eep_array[1024] __attribute__ ((section (".eeprom")));
> >
> > I use array as temporary storage.
>
> In the EEPROM? So you use the various eeprom functions in avr/eeprom.h
> to read and write this area? You know you can't just use it like
>
> eep_array[3] = 'C';
>
> right?

Right. I do not have a problem to access EEPROM. I usee
eeprom_read/write functions. The question is how to minimize HEX image
for EEPROM. I need something like non initialized data in EEPROM.
> > The make produces hex file for
> > EEPROM image that is 1024+1 = 1025 bytes long. Actually I do not need
> > eep_array to be initialized and thus do not want to burn it. Do you
> > see any chance to declare some place in eeprom but make it non
> > initialized and do not have it in EEPROM image hex file to minimize
> > burning time.
>
> Given that config_data is at the beginning of EEPROM, why not just use 0
> as its EEPROM address? After all, you can't directly read and write to
> EEPROM anyway; you have to use the EEPROM functions and give them
> offsets into EEPROM.
>
> What I generally do is to define a pointer to the beginning of EEPROM by
> taking the address of the first EEPROM data item I've defined, and then
> calculate offsets from it to various data items in EEPROM.
This is not a problem. I know exactly hot to access all my data in
EEPROM. I only say that some of that data is not initialized and thus
I do not want to see it in HEX file. But I do want the place to be
allocated.

As far as I can see I will have to declare special section without
"loadable" flag so that it will not be taken to produce image. This
may require to access linker scripts and I do not want to do it very
much. Probably there is any other option?

> --
> Ned Konz
> address@hidden
> http://bike-nomad.com


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