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Re: [avr-gcc-list] pre-loading the internal EEPROM

From: Tyler Hall
Subject: Re: [avr-gcc-list] pre-loading the internal EEPROM
Date: Sat, 14 Jun 2003 23:48:37 -0700 (PDT)

There are a couple of ways to do this, without knowing
the kind of data you want in the hex file it'll be up
to you to decide what's the most efficient...

The .hex file is an "Intel HEX" format file. All it
knows is what data goes into what address. If you just
have a little bit of data to into the hex file and you
really want to produce each hex file "by hand" (I'm
assuming you really mean a script to do this dirty
work for you?) you should do a google search on the
intel hex format. Each line in the hex file goes
something like this:


which says to put 0xAA into address 0x00, 0x55 into
0x01, 0xAA into 0x02, etc. because the first set of
hex digits are the address, the rest of the line is
the data. Don't quote me on the field lengths there, I
just made them up.

Now if you've got a lot of non-chaotic data, ie.
structured data, for each avr chip, you might want to
reconsider using C to for the job, and just use a
struct with a lot of #defines that get filled in at
compile time.

Tag the structure with the appropriate EEPROM
attribute (see avr-libc manual) and run gcc. The
output of the compile just has to be an OBJ (ie. no
linking), then run avr-objcopy to extract the EEPROM
section from the OBJ and put it an IHEX output file.

Here's an example, but again don't quote me on this,
it's 2am here as I type this...

struct eepromStruct {
   char serialNum[8];
   char deviceName[32];
   int someProperty;
} eepromInstance EEPROM_ATTRIBUTE_HERE = {

gcc -c eeprom_data.c -DSERIAL_NUM="01234567"
-DDEVICE_NAME="Hello, my name is ..."

avr-objcopy -j .eeprom -O ihex eeprom_data.o


--- Max Klein <address@hidden> wrote:
> Right, that's not the problem I have. AVR Studio's 
> integrated ISP interface has an option to upload a
> .hex 
> file into the EEPROM, similar to the .hex files
> created by 
> gcc to load into the main flash. My question is, how
> do I 
> create the .hex file for the EEPROM contents only? I
> don't 
> mind writing a fake C program to generate the .hex
> file 
> with the contents, but I don't want to actually
> program 
> the flash, only the EEPROM. The only information
> that I've 
> seen for loading contents into the EEPROM is via
> function 
> calls in the main (flash) program to load data byte
> by 
> byte; all I want is to create some kind of an image
> of the 
> EEPROM memory, and dump it directly into the chip.
>      --Max
> On Sat, 14 Jun 2003 22:05:59 -0400 (EDT)
>   "Christopher X. Candreva" <address@hidden>
> wrote:
> >On Sat, 14 Jun 2003, Max Klein wrote:
> >
> >>
> >> The Problem:
> >> All I want to do is create a .hex file (or
> whatever else
> >> works) with the EEPROM contents (byte-by-byte) so
> that I
> >> can mass-program my devices, and then go back and
> >>program
> >> the EEPROM on each device individually with an
> ISP. I
> >
> >Any programmer should be able to do this. I know
> uisp 
> >(under Linux) does.
> >
> >
> >Chris Candreva  -- address@hidden -- (914)
> 967-7816
> >WestNet Internet Services of Westchester
> >http://www.westnet.com/
> _______________________________________________
> avr-gcc-list mailing list
> address@hidden
> http://www.avr1.org/mailman/listinfo/avr-gcc-list

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