programming Atmega64 eeprom

[Sara]

Dear friends ;
I am working with avr Atmega64 chip on a project .In my project i have
to save my last data in a variable in eeprom and reload it in the
flash variables when the chip is being restarted .
I program the chip with JTAG ICE STK 500 programmer.i use these code
in my program that is written in code vision for saving the data:
//variable definition
eeprom int eeGP;
int GP;
;/main function
eeGP=0x08;
GP=eeGP;

the problem is that in first programing i give a value to the eeGP and
i expect that after programming the chip if i erase the flash and
reload the program without giving a value to the eeGP the value of GP
changes to 08.(the eeprom has been programmed) but the thing happen
is that after reloading the program to the chip the GP takes the
0xFFFF value that means the eeprom hasn't been programmed.
I have enabled the fuse bit (preserve eeprom on each chip erase.

Thanks in Advance

 

[J.A. Legris]

Dear friends ;
I am working with avr Atmega64 chip on a project .In my project i have
to save my last data in a variable in eeprom and reload it in the
flash variables when the chip is being restarted .
I program the chip with JTAG ICE STK 500 programmer.i use these code
in my program that is written in code vision for saving the data:
//variable definition
eeprom int eeGP;
int GP;
;/main function
eeGP=0x08;
GP=eeGP;

the problem is that in first programing i give a value to the eeGP and
i expect that after programming the chip if i erase the flash and
reload the program without giving a value to the eeGP the value of GP
changes to 08.(the eeprom has been programmed) but the thing happen
is that after reloading the program to the chip the GP takes the
0xFFFF value that means the eeprom hasn't been programmed.
I have enabled the fuse bit (preserve eeprom on each chip erase.

Thanks in Advance

Are you really trying to reload FLASH variables when the chip is being
restarted??? You can change data in FLASH but that would mean
reprogramming the chip using ISP.

I think you mean reload SRAM variables, which is evidently what you
are trying to do in the code posted above. If you reprogram the chip,
while preserving EEPROM, you should expect the data in eeGP to remain
at 0x08, but the value of GP will be indeterminate when the program
starts, depending on the data initialization properties of your C
compiler. After you run the program, GP should reflect the value of
eeGP.

How are you checking the value of GP? With a debugger?

By the way, you should use commas, etc., when you write. A little more
punctuation (and capitalization) would have made your post much easier
to read.

Like this:

The problem is that in first programing I give a value to the eeGP and
I expect that after programming the chip, if I erase the flash and
reload the program without giving a value to the eeGP, the value of GP
changes to 08 (the eeprom has been programmed). But the thing [that] happen
is that, after reloading the program to the chip, the GP takes the
0xFFFF value that means the eeprom hasn't been programmed.
I have enabled the fuse bit (preserve eeprom on each chip erase).