Operation without battery (GTA02)

[Andy Green]

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Somebody in the thread at some point said:
| Andy Green wrote:
|> Somebody in the thread at some point said:
|> |> And temp in 0.25 Kelvin
|> |> steps --> Celcius in 0.1 steps.  But this is basically scaling up
|> |> operation and you see otherwise unmassaged data.
|> |
|> | ?
|> | 1K step = 1 degree Celsius step
|>
|> "Scaling up operation" refers to the sentence before that you snipped:
|>
|> ''Some of the coulomb counter data is actually directly provided in very
|> funny units relative to a sense resistor outside the chip (20mR in our
|> case), the driver does the recommended computation and normalizes them
|> to uV and uA as required by power_supply APIs.''
|
| So this is not saying that a .25K step is a .1C step?

Wow no, the guy on top of these quotes was asking if we send raw data
from Coulomb Counter chip down /sys.  What I was explaining is it is
pretty raw, but power_supply mandates we report in 0.1C steps and the
chip gives us 0.25K steps, therefore we rebase Kelvin to Centigrade and
then convert the granularity to 0.1C, itself actually a "scaling up
operation", ie we are not losing information.  You can see all this in
the link I gave to the driver:

~ 245         case POWER_SUPPLY_PROP_TEMP:
~ 246                 v = hdq_read16(di, BQ27000_TEMP_L);
~ 247                 if (v < 0)
~ 248                         return v;
~ 249                 /* K (in 0.25K units) is 273.15 up from C (in 0.1C)*/
~ 250                 /* 10926 = 27315 * 4 / 10 */
~ 251                 val->intval = (((long)v * 10l) - 10926) / 4;
~ 252                 break;

- -Andy
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