[Owfs-developers] Changing offset on B1-R1-A

[Michael Hughes]

I was trying to change the offset on my barometer with:

echo "159" > /1-wire/1F.C9D1/main/26.113A2000/B1-R1-A/offset

this hung and when I tried looking at the B1-R1-A directory with a ls,
that hung also.  Now owfs seems to be hung itself.

I am running FreeBSD 9.3-RELEASE-p39 #4
I built owfs from the ports collection and it is owfs-3.1.p1
I built fuse kernel module from the ports collection.

-- 
Michael D HughesLoghome living is the best!

mich...@thehugheslogcabin.net

--
___
Owfs-developers mailing list
Owfs-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/owfs-developers

Re: [Owfs-developers] Owserver on pi (zero) using DS18B20 and pullup resistor

[Jan Kandziora]

Am 04.09.2016 um 19:08 schrieb Colin Law:
> 
> I have it to 3.3V ok. So 4.7k is ok for 3 wire mode but for parasitic
> it should be 1.5k
> 
Yes.

> 
> To summarize then, for parasitic mode I should not need an external
> strong pullup and should be able to use just a 1.5k pullup and to
> specify
> dtoverlay=w1-gpio,gpiopin=4
> and
> sudo modprobe w1-gpio pullup=1
> 
> With in addition the 3.3 to 5V level shifter as in your first post if
> any devices on the bus need 5V
> 
Yes.


>> There are two drawbacks when you use such a strong "weak" pullup. First,
>> the power consumption. I think that's negligible. Second, heating up the
>> sensor from inside by its bus output transistor. That's negligible as
>> long as you don't measure low temperatures.
> 
> My rudimentary knowledge of thermodynamics tells me that if one
> provides a certain amount of power from inside as you suggest and that
> heats the device by (for example) 0.1 degrees when the device is in
> ambient 0C, then if the device were in ambient 50C then the heating
> would still be the same (0.1 degrees).  Is that wrong?
> 
It's a constant heat amount. Not a constant temperature amount.
Temperature inside the sensor is a derivative value.

That said, when someone mentions the absolute temperature of something,
you can immediately say it's about radiation. Heat radiation works much
better at higher temperature. It goes with T^4.

So, at lower temperature, changes of the sensor temperature in reaction
to ambient temperature will be much slower, and internally generated
heat can make a difference when sampling the temperatures often.

For your application, you always have to check if radiation is dominant.
If your answer is yes, be aware absolute temperature matters.


Kind regards

Jan

--
___
Owfs-developers mailing list
Owfs-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/owfs-developers

Re: [Owfs-developers] Owserver on pi (zero) using DS18B20 and pullup resistor

[Colin Law]

On 3 September 2016 at 13:04, Jan Kandziora  wrote:
> Am 03.09.2016 um 10:36 schrieb Colin Law:
> ...
> 2. You have to put
>
> dtoverlay=w1-gpio,gpiopin=4
>
> or
>
> dtoverlay=w1-gpio-pullup,gpiopin=4,pullup=5
>
> into your Raspberry Pi boot partition config.txt. And of course, the
> w1-gpio resp. w1-gpio-pullup dtb files have to be present in the boot
> partition overlays directory. Then reboot.

Could I ask for further clarification on this please?  I have used
dtoverlay=w1-gpio,gpiopin=4
and installed the kernel module using
sudo modprobe w1-gpio
and the DS18B20 works fine in three wire mode with a 4.7k pullup on DQ

Google tells me (Ithink) that if I use
dtoverlay=w1-gpio-pullup,gpiopin=4,pullup=5
then I can use parasitic mode with an external strong pullup driven by
gpio05 in the way described in [1]
However other results appear to suggest that I can use parasitic mode
without the strong pullup, and I have also seen suggestions that to
install the module I could use
modprobe w1-gpio pullup=1
and I have been unable to determine exactly how the various options
relate to each other.

Further clarification would be much appreciated.

Regards

Colin

[1] 
https://hatfors.wordpress.com/2015/09/12/measuring-temperature-with-a-parasite-power-1-wire-sensor-raspberry-pi-and-integrating-into-ose-using-haskell/
>
>
> 3. You have to use --w1 for this. The w1 kernel driver is the only way
> to use the bitbanging host adapter.
>
>
> 4. You have to update your owfs to 3.1p1 or later, because Debian Jessie
> uses kernel 3.16.x, and there was a long-unseen incompatiblity between
> post-3.16rc kernels and pre-3.1p1 owfs.
>
> You can use the owfs packages from the Raspbian testing repository. Edit
> (or create) your /etc/apt/preferences to contain:
> --
> Package: *
> Pin: release o=Raspbian,a=stable
> Pin-Priority: 500
>
> Package: *
> Pin: release o=Raspbian,a=testing
> Pin-Priority: 300
> --
> This is important so you keep stable (Jessie) for all packages but the ones
> explicitly taken from testing (Stretch).
>
>
> Then, add a line
> --
> deb http://mirrordirector.raspbian.org/raspbian/ testing main contrib 
> non-free rpi
> --
> to your /etc/apt/sources.list to get access to the Raspbian testing
> repository.
>
> Do an
>
> $ sudo apt-get update
>
> to read the package metadata, then check
>
> $ sudo apt-cache policy
>
> whether the testing repo is there with priority 300. Then
>
> $ sudo apt-get update -t testing owserver ow-shell
>
> That should install all you need, including the startup files and systemd 
> units.
> Note you have to edit /etc/owfs.conf again to contain (this and only this)
> --
> !server: server = localhost:4304
> server: w1
> --
> Restart the owserver service after that.
>
>
> Done.
>
>
> Kind regards
>
> Jan
>
> --
> ___
> Owfs-developers mailing list
> Owfs-developers@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/owfs-developers

--
___
Owfs-developers mailing list
Owfs-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/owfs-developers