Seeking your opinion on ways to report both Altitude and Pressure sensors for the DPS310 as well as Temperature from dbus-sensors.

[Bruce Mitchell]

On 6/2/2021 09:03, Ed Tanous wrote:
> On Wed, Jun 2, 2021 at 8:58 AM Bruce Mitchell
> <bruce.mitchell at linux.vnet.ibm.com> wrote:
>>
>> On 6/2/2021 08:39, Ed Tanous wrote:
>>> On Tue, Jun 1, 2021 at 8:43 AM Bruce Mitchell
>>> <bruce.mitchell at linux.vnet.ibm.com> wrote:
>>>>
>>>> Hello Ed,
>>>>
>>>> It has been suggest I seeking your opinion on ways to report both
>>>> Altitude and Pressure sensors for the DPS310 as well as Temperature from
>>>> dbus-sensors before going to far down the road.  Thus that is what I am
>>>> attempting to do in the email, others on the mailing list input is
>>>> desirable as well.
>>>
>>> Thanks for discussing this before getting too far along.  I haven't
>>> worked on any systems with physical pressure sensors, but I'm excited
>>> to see new things get added.
>>>
>>>>
>>>> As I see it, Altitude and Pressure are different in that
>>>>        1) Altitude is computed base off of essentially a policy
>>>
>>> I have no idea what this means.....   In what way is altitude a
>>> "policy"?  Can you elaborate a little?
>>>
>>
>> I view a mechanism is something like update a FLASH part with
>> an image provided.
>>
>> I view a policy is what decides if the the update of the FLASH part
>> with the specific image is allowed.
>>
>> I the case if Pressure and Temperature I view them as mechanism,
>> merely a simple reading and possibly some well defined computations
>> that are universal.
>>
>> With Altitude computed from Pressure there are several ways to
>> compute the Altitude and they are not universal.  So I see it as
>> a policy of which Pressure to Altitude model is chosen and why.
> 
> Sounds like I interpreted your intention correctly. (I think).

I believe you did.

> 
>>
>>>>        2) Pressures is a read measurement which is a mechanism
>>>>        3) Temperature is a read measurement which is also a mechanism
>>>
>>> I'm really struggling with the above to understand what you're getting
>>> after, so if I go down the wrong path, please forgive me.
>>>
>>> I think what you're saying is that altitude is calculated based on
>>> pressure + some transfer function to determine an altitude?  And that
>>> transfer function might be fungible depending on the platform?
>>>
>>> If I got the above right (big if) I would probably expect a new
>>> pressure sensor type to be added that reports a pressure sensor, then
>>> we'd put the transform code in something that looks a lot like CFM
>>> sensor (which oddly enough has a hardcoded 0 for altitude in its
>>> algorithm for systems without pressure sensors).  Considering how
>>> related a pressure sensor is to altitude, I could see putting them in
>>> the same application if you wanted;  It might simplify the code some.
>>>
>>>
>>> I think overall a better picture of what you're wanting to accomplish
>>> would be a good place to start, then we can iterate from there on what
>>> pieces we need that are new.
>>
>> I have Temperature, Pressure, possibly Humidity sensors all which are
>> variables to different models to compute Altitude from.  I do not have a
>> true Altitude sensor.
> 
> This sounds exactly like the CFM sensor, and Exit air temp sensor;
> Most systems don't have exit air temp sensors, but they have input
> power and individual fan speeds, which can be put into models to
> determine CFM and ultimately exit air temperature.  I would expect
> Altitude to do something very similar in code (although with a
> completely different algorithm).
> 

So the DPS310 has 2 sensors in it a Pressure and a Temperature sensor.
Do I create a Pressure reading and a Temperature reading for the DPS310
and then add Altitude to it as well?

Or do I create 3 separate things,  one for each Pressure, Temperature,
and Altitude?

Also I believe I should be looking to the CFM sensor and Exit air 
temperature sensor as reference examples.

>>
>> I am being asked to provide Altitude.
>>
>> Personally I believe the desired feature is how much cooling a parcel of
>> air per unit of time.  Thus I would think air Temperature, Humidity, and
>> Density (probably compute-able from Pressure, but I have not checked on
>> the specifics) would be the important factors.