[Voyage-linux] Negative temperature reading on Wrap

[Beat Meier]

Tommaso Cavanna - Wave s.r.l. wrote:

> Hello to everybody,
>
> this is my first message to the mailing list.
>
> First of all I would like to thank everybody worked on Voyage since 
> it’s very stable and useful.
>
> I have successfully installed and configured Voyage 0.2 pre1 on Wrap 
> board with CM9 card.
>
> Following the Readme instructions I have installed the LM77 driver to 
> read the board temperature.
>
> After the LM77 driver installation I got a new directory 
> /sys/bus/i2c/drivers/lm77/0-0048/ and I read the sensor temperature 
> with: cat temp1_input.
>
> I got reasonable readings while the temperature board is higher than 
> 0°C; since I’m testing the behaviour of the router under 0°C I cooled 
> down the Wrap board to -10 °C.
>
> The board correctly booted-up, and I can enter the ssh login in order 
> to read the LM77 temperature, but when I read the temp1_input value I 
> get: 4095000 value.
>
> Since I expected a negative value, what does it mean 4095000?
>
> Has anybody performed under zero degree measurements with LM77?
>
I had the same problem when I read in an intervall of 1 second. There 
seems to be a problem if you read "rapidly" the values
or something else goes wrong. I had started a therad in august at 
lm-sensors at lm-sensors.org which came to no conclusion.
Rudolf was busy (as I remembre) and so was I ...
Just about 2 days I had a question from a person about this. He will 
maybe try to figure out with the user Rudolf Marek
(see thread august 
http://lists.lm-sensors.org/pipermail/lm-sensors/2005-August/013339.html)

I've heared that Rudolf Marek is also on irc

#linux-sensors auf irc.freenode.net

Let the list know if you know anyhing

Greetings

Beat

> Tom
>
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