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

[Jef Driesen]

On 2017-05-10 15:43, Anton Lundin wrote:
>> >That said, I think setpoint values are still interesting to see, to
>> >validate how well the controller did manage to try to keep the o2 close
>> >to the setpoint.
>> 
>> After looking at the data, I had the impression that the setpoint
>> value is "unused" because it seems to just contain some "dummy"
>> value (for example the last used value, or some default value).
>> 
>> I'll illustrate with an example dive from Steve's Petrel (*). This
>> dive has a fixed setpoint of 0.70 on every sample, but the ppo2
>> values range from 0.32 to 1.74!
> 
> This sounds like a mCCR. Then its up to the diver to press a button
> until the ppo2 matches what the diver would like to have.

That makes sense!

>> (*) I can send you the data if you want to take a look. I don't know
>> if Steve is okay with sending his dives to a public mailinglist, so
>> I didn't attach it to this email.
>> 
>> To me that doesn't look like the dive computer is even trying to
>> keep the ppo2 close to the setpoint. At least not to the setpoint
>> value that's stored in the sample. Hence my question whether this
>> value is relevant or not?
> 
> I think so.
> 
> My guess is that the setpoint is what the computer will continue to use
> as its ppo2 value if it looses the connection with the sensors.
> 
> Its better to expose the information to the user, and let the user
> ignore/delete it if they don't care about it.

My only concern here is that if the info is useless, like those zero 
millivolt values when external O2 sensor monitoring is disabled, the we 
better don't report them at all. But if that's not the case, then it's 
of course fine to keep reporting them.

>> >The only real comment about the code is that I would have liked to see
>> >the calibration factor kept as a int, and just change the unit factor
>> >from .00001 to .000022, between the models.
>> 
>> What would be the advantage of that? That would mean yet some other
>> field to store the scaling factor, or doing some "if (model ==
>> PREDATOR)" when calculating the ppo2. Now it's just done once in
>> advance, making the conversion from millivolt to ppO2 independent of
>> the model. I'm even tempted to pre-multiply the value with the
>> 100000.0 factor too, to get rid of an extra
> 
> I'd store it as a separate calibration factor unit. Anyway, if you
> multiply the calibration factor with 2.2 as of now, its better to
> include the 1/100000 factor to, rather than having them in two separate
> places.

I replaced your patch with your latest version, and updated the rest of 
the series. Please have a look. If you are okay with the changes, I'll 
merge them to master.

Jef
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