How to store float in EEPROM??

[Falgellus]

If you see the ccs help you can find this:

-----------------------------------------------------------------------------
How do I write variables to EEPROM that are not a byte?

The following is an example of how to read and write a floating point number from/to EEPROM. The same concept may be used for structures, arrays or any other type.


· n is an offset into the eeprom.
· For floats you must increment it by 4.
· For example if the first float is at 0 the second
· one should be at 4 and the third at 8.

WRITE_FLOAT_EXT_EEPROM(long int n, float data) {
int i;

for (i = 0; i < 4; i++)
write_eeprom(i + n, *(&data + i) ) ;
}

float READ_FLOAT_EXT_EEPROM(long int n) {
int i;
float data;

for (i = 0; i < 4; i++)
*(&data + i) = read_eeprom(i + n);

return(data);
}
-----------------------------------------------------------------------------

I tried it but seems to have problems in this expression:

*(&data + i) = read_eeprom(i + n);


I tryed doing test for a lot of time but the best I can get is these functions that runs well:


WriteFloatToEEprom( byte Addr, float data )
{
int32 a;
a = (int32) ( data * (float)100 );

Write_EEPROM ( Addr , (byte) ( a & 0x000000FF ) );
Write_EEPROM ( Addr +1, (byte) (( a & ( 0x0000FF00 ) ) >> 8 ) );
Write_EEPROM ( Addr +2, (byte) (( a & ( 0x00FF0000 ) ) >> 16 ) );
Write_EEPROM ( Addr +3, (byte) (( a & ( 0xFF000000 ) ) >> 24 ) );

}


////////////////////////////////////////////////////////////////////////////////
float ReadFloatFromEEprom( byte Addr )
{
float data;
int32 d2;

d2 = (int32) Read_EEPROM ( Addr );
data = (float)d2;
d2 = (int32) Read_EEPROM ( Addr+1 ) ;
data = data + (float)( d2 << 8 );
d2 = (int32) Read_EEPROM ( Addr+2 ) ;
data = data + (float)( d2 << 16 );
d2 = (int32) Read_EEPROM ( Addr+3 ) ;
data = data + (float)( d2 << 24 );
data = (float) (( data / 100.00) + 0.000001 );

return(data);
}


Have anybody a better way?

THANK YOU VERY MUCH


Paolo

[Ttelmah]

You need to change the way the address arithmetic is done. Use:

[Falgellus]

Thank you very much Ttelmah, changing as you said all is ok.

Bye