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how to write float to eeprom and read float from eeprom

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arash rezaee

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how to read from eeprom and convert it to float

Hi every one
I am using ATXmega128A1 and the compiler is codevision. Does any one know how to convert 4byte to fload which I stored them into eeprom and I don`t know how can I convert them to float again.
this is the code i used to convert float to byte:
union
{
float KX1;
unsigned char bytevalue[4];
}variable;
Please help me.
Regards
Arash
 
Last edited:

Thanks. I used union and sounds like it works. but I don`t know how to convert 4byte to float using union. Do you know?
 

You don't convert anything to a union, it's a shared memory space that can be referred to in different ways. Save your float to a union consisting of 4 bytes then save the bytes one at a time to EEPROM. To read from the EEPROM, save bytes in consecutive byte sized locations in the union and read it as a float type.

Brian.
 

You don't need to make any conversion, just use

Code:
eeprom float my_float;  // variable stored in eeprom
 

Do you want to represent something like 0xABCD (4 bytes) as float 43981.000?
 

ok, thanks. I will check it and get back to you.

- - - Updated - - -

You don't need to make any conversion, just use

Code:
eeprom float my_float;  // variable stored in eeprom

you mean in codevision??? But I wrote my own code to write and read from eeprom. Is it really simple? what about If I what to read from eeprom( I mean for floats)? I must mention that I have 10 float number that I need to store them to eeprom.
thanks

- - - Updated - - -


yes. I have 10 coefficients and they are like 27.85451 and so on. so I want to store them and later read them and use them.
Cheers
 

codevision simplifies that process for you.

you use
Code:
eeprom variable_type variable_name= initial_value;

To read a float variable just use the name it has


Code:
eeprom float my_eeprom_float=0.0;  // variable stored in eeprom initializes to 0
float my_ram_float;  // RAM variable

my_ram_float=my_eeprom_float;   // copy eeprom to ram

my_eeprom_float=my_ram_float;   // copy ram to eeprom
 

codevision simplifies that process for you.

you use
Code:
eeprom variable_type variable_name= initial_value;

To read a float variable just use the name it has


Code:
eeprom float my_eeprom_float=0.0;  // variable stored in eeprom initializes to 0
float my_ram_float;  // RAM variable

my_ram_float=my_eeprom_float;   // copy eeprom to ram

my_eeprom_float=my_ram_float;   // copy ram to eeprom

That a lot. one more question: Where does it store in eeprom? I mean Does it store it in first page and so on or it is random? I have more valiables which I need to store in eeprom but they are char and I wrote my own code to store them in specific address of eeprom which I address it. So does this type of storing interfere with other datas?
 

This way you have no control of the exact position but I think there is another way to specify the exact address.
Check the manual.

You can also use the same way for all eeprom variables

Code:
eeprom char my_char;
eeprom integer my_integer;
eeprom char my_array[10];
....
 

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