[lm-sensors] Andigilog asc7621 driver: Temperature scaling

[Jean Delvare]

On Sun, 07 Mar 2010 10:20:13 +0000, Ken Milmore wrote:
> Regarding the scale factors, I think you'll find that those given for 
> the 2.5V, 3.3V and 5V ranges are far enough wrong introduce a 2-bit 
> error in the 10-bit values.  The driver goes to some trouble to get the 
> full 10 bit precision by combining both the MSB and LSB registers, then 
> throws that precision away in the calculations!
> 
> You really do need to use the 3/4 scale voltage values, or some 
> equivalent rational scaling, to get the right answers here.  That's why 
> Andigilog provide them in the data sheet! :-)

Whether you use the full scale or 3/4 scale voltage values as the base
for the calculation doesn't matter, both can work as long as the
calculation is consistent. What really matters is to multiply before
you divide.

> I will try and get a patch together as soon as time permits.

Great, thanks.

-- 
Jean Delvare