[Openec] temperature sensor

[Richard A. Smith]

Frieder Ferlemann wrote:

> two questions regarding the temperature sensor:
> - where is it?)

R363

Start at the DC power jack and move up until you see the connector for 
the speaker. R363 is just below it.


> - how does ADC reading translate into degC?
>   (or preferrably: which part is used and how does it connected to GPIAD0)

Its a 10k_NTC hooked up in the classic voltage divider setup.

<Fixed width font>
   10k ohm          10k NTC
3.3V --/\/\/\--|--/\/\/\/--- gnd
                |
                |
              Vout

</Fixed width font>

On your B1 however, the 3.3V source is not powered unless the DC adapter 
is plugged in.

I don't have any data on the beta and whatnot of the NTC. I've asked but 
never got a response.  I suspect the values in the EC code are 
empirically determined.  You will just have to generate the calibration 
curve with data readings of know points.

-- 
Richard Smith  <richard at laptop.org>
One Laptop Per Child