Values of CC Gain and CC Delta

Helder,

You can use the document SLUA640, available for download from the TI website, to see an example of calibrating the current and finding the CC Gain and CC Delta. The typical bqEVSW value for these parameters will be the sense resistor value. E.g. “1” for 1 mohm.

After i implemented that example to calibrate the current, i ran very experiments and i couldnt made this work.
With a fLoad=-1045 (1045mA) the result that i have reading the current register is 0x4B=43.It's obvious that this is wrong, in quantity and signal.
So, firts of all i want to make some questions that i have about this process.

In the current:
I read in others topics and i see some changes in the next formulas. I have this:

adj_ccOffset=(ccOffset/16.000f);

e=Raw_Calibration_Data;

ccGain = fLoad/(e-adj_ccOffset);

ccDelta = ccGain * 1193046.0f;

This is what is written in the document, is it what i really nead to make?

In the DF-write

Here have something wrong with the parenthesis
Shoul i use:
tmp_val=2^(8-exp)*(val-128);
or
tmp_val=2^(8-exp)*val-128;

And finally, is proven that this document work in bq34z100 or exists some diferences that i should now?

Best Regards.

 

Hello guys.

PDF documentation to this IC is the worst out of all I read. Very confusing.

CC Gain and CC Delta is written in F4 ;)) Of course it is not standard float (for example as Arduino uses)

How to calculate F4 value:

1. Byte on lowest address is used for exponent then e=byte-128-24
2. Other 3 bytes is mantissa. Highest bit is sign.
3. Set this highest bit (OR 0x80) then convert to long so you get m
4. F4_value= m*2^e


Anyway, TI, why you couldn't use standard float and just put it in mOhms into flash??? That would be easy for designers.

Cheers,

Hello Thomas.

Anyway what is the difference between CC Gain and CC Delta?

Haw you designed this fuel guage IC? It is remarkable how many functions and settings it has. ;)

Cheers,

Drahomir,

The floating point implementation is different from the standard algorithm and the document that I sent is all that I have to offer in calculating the values. The CC Delta and CC Gain are not the same and the document also provides a flow chart to calculate these parameters. The bq34z100 datasheet has a table that provides the data flash to EVSW conversion factors.

Regards
Tom

WOW.. THANK YOU FOR POSTING that..
I too have had no luck deciphering the Floating point value and just didn't have time yet to ask about it yet.

-TIm