Re: Pressure sensors

[Greg Troxel <gdt%lexort.com@localhost>]

Artturi Alm <artturi.alm%gmail.com@localhost> writes:

> On Tue, Jan 01, 2019 at 12:03:31PM -0500, Greg Troxel wrote:
>> So, I wonder why you are choosing kPa vs hPa, and if that choice ends 
>> up being a framework choice for everything.  And how the rest of the
>> world deals with this issue.
>
> By accident, i guess, and after having read about pascals on wiki[0],
> it felt like a good choice, for being "not just for meteorologists",
> nor imperial, but i'm from metric .eu, fwiw..

Interesting article, and it seems right.

Atmospheric pressure is basically meteorology, IMHO.

> I actually got *= 1000 for mPa in the driver, so i don't really care
> about the unit to be used, as long as it's not loosing any precision/
> limiting range (for kernel -> user, so Pa would work just as well, and
> i'm not sure whether mPa does buy anything w/r.t. future sensors, it
> was more about minimal diff looking reasonable).

The comments about integers, range and precision are compelling.  It's
hard to imagine anything in envsys delivering more than 1 Pa of
precision.

I didn't mean to give you a really hard time about this.   It just felt
like a decision that was likely to control how all envsys pressure
reporting is done in NetBSD, for all time.  But maybe I'm misperceiving
that.