[PATCH] Visualisation of individual oxygen sensor data for CCR dives

Anton Lundin glance at acc.umu.se
Wed Apr 12 01:47:57 PDT 2017

On 12 April, 2017 - Davide DB wrote:

> On 11 April 2017 at 23:44, Jef Driesen <jef at libdivecomputer.org> wrote:
> >
> > I'll need to look again at the old discussion, but if I remember
> > correctly, your patch produced bogus results for some of the data I tested
> > against. And that's why I wanted to double check with Shearwater. But so
> > far I wasn't able to get any info from Shearwater. So yes, let's have
> > another look

Directly after that revision of the patch, I sent you another which
always handled the calibration values the same, no matter what they
were, which produced sane values even in that case.

I didn't have that test data you referenced when developing the code,
but after seeing that data, it clear that its the right thing to do.

> Maybe I'm really messing up things but reading Dirk email regarding his
> contact at Shearwater "Perdix / Perdix AI info from Shearwater" it seems
> that Perdix and Petrel devices don't carry O2 info via their protocol:


> They carry only a global pO2 (I guess it's the result PO2 from so called
> voting logic hence used in all further calculation) and mV values for each
> sensor. BTW individual mV 02 sensor graph was added in version 2.3.5:
> https://www.shearwater.com/release-notes-firmware/shearwater-desktop-2-3-5-released/
> <https://www.shearwater.com/release-notes-firmware/shearwater-desktop-2-3-5-released/>
> Hence would be impossible to display single individual pO2.

No, its not impossible. The calibration values are in the Dive header,
and with those, the mV values can be converted into pO2 values.

The issue with current libdivecomputer DC_SAMPLE_PPO2 is that you cant
distinguish between ha "real" "voted" pO2 and the raw sensor value.

I would like to see a option to export both, and be able to handle them

> > For the Shearwater Petrel CCR divers reading this: Can you supply us with
> > some more data to test against? The Petrel protocol doesn't support memory
> > dumps, so you'll need to dump the individual dives. You can do that with
> > libdivecomputer' dctool:
> >
> > http://www.libdivecomputer.org/builds/stable/linux/dctool
> >
> > Execute with these options:
> >
> > ./dctool -v -l petrel.log -f petrel download -o dive.%n.bin -f raw
> > /dev/rfcommX
> >
> > Send back the petrel.log and all the dive.*.bin files.
> Is there something equivalent for a Windows CCR user? :-)


replace /dev/rfcommX with COMX


Anton Lundin	+46702-161604

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