[PATCH] Unify sample pressure and o2pressure as pressure[2] array

[Willem Ferguson]

On 20/07/2017 23:48, Linus Torvalds wrote:
> From: Linus Torvalds <torvalds at linux-foundation.org>
> Date: Thu, 20 Jul 2017 14:39:02 -0700
> Subject: [PATCH] Unify sample pressure and o2pressure as pressure[2] array
>
> We currently carry two pressures around for all the samples and plot
> info, but the second pressure is reserved for CCR dives as the O2
> cylinder pressure.
>
> That's kind of annoying when we *could* use it for regular sidemount
> dives as the secondary pressure.
>
> So start prepping for that instead: don't make it "pressure" and
> "o2pressure", make it just be an array of two pressure values.
>
> NOTE! This is purely mindless prepwork.  It literally just does a
> search-and-replace, keeping the exact same semantics, so "pressure[1]"
> is still just O2 pressure.
>
> But at some future date, we can now start using it for a second sensor
> value for sidemount instead.
>
> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> ---
I have been doing quite a bit of sidemounting with two pressure 
transducers. For the Galileo, the requirement is that I have to notify 
the DC every time I switch from one cylinder to another. This way, I 
really need only one set of pressure values because I do not use more 
than one cylinder at a time. The Galileo stores only one pressure value, 
regardless of how many cylinders are instrumented.

I gather that some of the newer DCs now actually store more than one 
cylinder pressure at a time? If pressure data for both cylinders are 
stored for each depth measurement this might remove the necessity of 
needing to select the appropriate cylinder on the DC while diving. I 
doubt if one would want to graph both of the pressure values 
simultaneously on the dive profile, as is the case for dil/o2 in CCR.  
But I suspect that one would still have to tell Subsurface when cylinder 
switches were made in order to correctly interpret these pressure data.

Please give a bit more information on how the Perdix AI and the G2 
handle pressure data? I cannot get much technical information from the 
web sites. E.g. on the Perdix AI page it says it can handle two pressure 
transducers but it does not say how the data are stored and presented on 
download. I suspect the G2 is very similar to the Galileo.

Kind regards,
willem