Patches to add basic support for the Suunto EON Steel

[Artur Wroblewski]

On Thu, Oct 30, 2014 at 5:17 PM, Linus Torvalds
<torvalds at linux-foundation.org> wrote:
> On Wed, Oct 29, 2014 at 5:00 PM, Artur Wroblewski <wrobell at pld-linux.org> wrote:
> >
> > The 15 tissue compartments half-times are documented in the Suunto manual.
>
> Hmm. Interesting. I hadn't actually noticed that, but right you are.
> Not that they are exhaustively documented, but the Nitrogen half-times
> for the compartments are indeed there (with "halftimes are divided by
> a constant factor to obtain helium halftimes")

It seems, I have exaggerated the documentation part. The constant is probably
around 2.65 (helium diffuses 2.65 faster than nitrogen). In [1] Wienke says
"around 2.7" (pages 82-83) or "around 2.65" (i.e. page 143). Also, divide the
Buhlmann nitrogen half-times by helium ones (5 / 1.88 == 2.66).

> > IMHO, there is much more value in such information than in
> > Subsurface's recalculation of inert gas pressure in tissue
> > compartment recalculation with Buhlmann.
>
> I'm not sure that follows, though.. The ones we calculate are much
> better documented, and at least as well-tested as the one Suunto does,
> and you can actually see how changing the values and settings changes
> things, and how it affects the loading during the dive - while I can
> only download the saturation before/after the dive, with no logging of
> it during..

OK. I misread your e-mail thinking you get the data during the
dive as well.

[...]

Anyway, you have pressure of inert gas in tissue compartments. An application
using libdivecomputer could fetch the data to calculate surface intervals, no
fly time and for multi-day dive planning or apply it to some other use cases we
cannot predict here. A calculation does not have to use the same decompression
model principles as the one implemented in a dive computer.

Inert gas pressure in tissue compartments data is quite common in many
decompression models (ZH-L16, VVAL 18, VPM, RGBM) and, if I understand
well, the Cochran backend could provide such data, too. We could ask
HeinrichsWeikamp to have it in OSTC dive computers.

Therefore, IMHO, it would be good to model this data as, for example, a list of
pressure values (in unit used by libdivecomputer for pressure) for each inert
gas (but not strings).

Regards,

w

[1] http://www.sergiodestro.com/decodoc/RGBM_Update8402.pdf