[Xastir] SHOW OF HANDS REQUESTED: Davis Weather Station users

[Tom Russo]

On Thu, Jul 19, 2012 at 01:34:14PM -0700, we recorded a bogon-computron collision of the <curt.we7u at gmail.com> flavor, containing:
> On Thu, 19 Jul 2012, Tom Russo wrote:
> 
> > I am unable to test anything rain-related here --- not only do I not have a
> > Davis unit (I have a LaCrosse), but I live in New Mexico.  We only get about
> > 7" of rain a year, and I'm invariably away from the computer on the day it
> > happens.
> 
> Well, rain I can do...  But Davis I cannot.  I have enough parts for two or three LaCrosse stations and one Dallas One-Wire station.

No good.


On the other hand, maybe if you can put one LaCrosse together and observe
the Own Weather Data screen over the span of a day or two of rain to see if
it reports data properly.

The issue is that Xastir needs a weather station to report "total rain" and 
uses the (monotonically increasing) value over time to compute 24-hour, 1-hour,
and since-midnight values, which it then reports as an APRS WX report.

The Davis code (and by extension, the LaCrosse code) reads 24-hour rain data
from the weather station and stores it in wx_rain_total --- incorrectly, as
far as I can tell.

Later, Xastir uses "cycle_weather" and uses this wx_rain_total to compute
24-hour and other values, but since Davis is already storing it as 24-hour,
it's going wrong because the value isn't a steadily increasing thing.

Also, the Davis code, unlike other code, doesn't call "compute_rain" right
after reading data, so some of the numbers are complete junk coming out
of the parsing code.  

The patch I sent to Mike copied a compute_rain call out of other parts of the
code, but I'm not convinced it's right yet --- especially since the Meteo
code (which is used also by LaCrosse) pulls 24-hour data out of the wx station,
not total rain.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick