Re: Pressure sensors

[Ignatios Souvatzis <is%netbsd.org@localhost>]

hi,

On Wed, Jan 02, 2019 at 06:31:22PM -0800, John Nemeth wrote:

>      I'm pretty sure that millibars and hPa is metric as well.

Yes, both are syntactic sugar for the SI unit. 
1 Pa = 1 N / m²
1 bar = 10⁵ Pa.

(1 bar happens to sound nice to old-schoolers, because it is slightly
more than 1 % off the average atmospheric pressure at sea level
(atm) and the technical atmosphere at, also nearly the same, which
is one kPond - that is the gravitational force of 1 kG at sea level
- per cm².)

But as we have all those decimal factor keywords, bar is superfluous,
and to get nice useful integer units, we need the milli- prefix
anyway (and hardcore meteorologists would even need dekapascal!)
Probably why meteorologists write hPa instead of mbar nowadays on
this side of the ponds. If you use floats anyway, kPa is as good as hPa.

I agreee that for anything we ever will use in our machines, unsigned
32bit integer Pascals are good enough. We can leave creating 64bit
µPa for the next generation.

	-is