Thanks for your response Gary! I agree with you.. I have done some more
digging and figuring (Texan for math) and can't figure out where the heck
the number is coming from.....
So here is what my sensor reads raw.. 95261.2968494 Pa...convert that to
hPa (Pa/100) and you get 952.612968494...Convert that to mbar (hPa = mbar)
and you get 952.612968494... convert that to inHg (mbar * .02953) and you
get 28.1306609596... this is in the QA range and would be recorded..
I did this in a text program I built using all of what MWall wrote for me
in my driver.. and it looks like this...
#!/usr/bin/python
import time
import Adafruit_BME280
from datetime import datetime
from time import strftime, localtime
sensor = Adafruit_BME280.BME280(mode=Adafruit_BME280.BME280_OSAMPLE_8)
pascals = sensor.read_pressure()
#time
start_time = time.time()
datetime = strftime("%H:%M:%S %m-%d-%y")
#Calcs
hPa = pascals / 100
mbar = hPa
inHg = mbar * .02953
#Print
print 'dateTime,', datetime
print 'Pa,',format(pascals)
print 'hPa,',format(hPa)
print 'mbar,',format(mbar)
print 'inHg,',format(inHg)
The output from my driver in what I think to be hPa is 2908.61213797. I
procured that reading by removing the * weewx.units.INHG_PER_MBAR from the
statement packet['pressure'] = self._sensor1.read_pressure().
I am stumped.. I will keep changing things till I get the right number..
but maybe this will shake something loose.
T
On Friday, April 7, 2017 at 7:58:37 PM UTC-5, gjr80 wrote:
>
> Hi,
>
> Straight up I can see you running into a units problem. In your driver you
> are using weewx.METRIC for field usUnits, so in other words all of the obs
> in your loop packet should be from the weewx.METRIC unit system, for
> barometer that is hPa. To calculate your barometer field you are taking
> your sensor reading (I presume that is in Pa but I am not sure) and then
> multiplying by a conversion factor that is in inHg/hPa, so the resulting
> value will be in some sort of derivative of inHg, definitely not hPa.
>
> I think you need to go back and trace through your barometer units very
> carefully, remember the conversion factor is not just a number, but it has
> units itself ie inHg/hPa. If you put values in US customary units in a
> METRIC packet they will be converted/stored /displayed incorrectly
> somewhere.
>
> Gary
>
> On 08/04/2017 8:23 AM, "Tommy Denton" <[email protected] <javascript:>>
> wrote:
>
>> I have a custom hardware setup.. the DH22 and BME280 are outputting data
>> las they should..(best I can tell)
>>
>> For my own quick and dirty webpage I did some maths to get pascals to
>> inHg but now I want to do this in weewx and with some expert help on this
>> forum I am like 98 percent there.. I have learned a lot but have hit the
>> wall I always hit when I can't find some code to read or I don't know what
>> code I am reading. Now I have read the manual and each time I get over one
>> of these hurdles more of that manual changes from greek to english...but
>> alas I am blocked by my own ignorance..
>>
>> So.. here is what I am doing for my own webpage..
>>
>> #Setup and pull data from the Sensor
>> #bme280
>> from Adafruit_BME280 import *
>> sensor = BME280(mode=BME280_OSAMPLE_8)
>> temperature = sensor.read_temperature()
>> pascals = sensor.read_pressure()
>>
>> #Setup and pull data from the Sensor
>> #AM2303
>> import Adafruit_DHT
>> sensor = Adafruit_DHT.AM2302
>> pin = 17
>> humidity, degrees = Adafruit_DHT.read_retry(sensor, pin)
>>
>> #Setup Time
>> #time
>> import time
>> from datetime import datetime
>> from time import strftime, localtime
>>
>> #Load up Converter
>> #calcs
>> from meteocalc import dew_point, heat_index
>> temp = degrees*9/5+32
>> baro = pascals/3386.389
>> dewpoint = dew_point(temperature=degrees, humidity=humidity)
>> heatindex = heat_index(temperature=degrees, humidity=humidity)
>>
>>
>> My sensor puts out Pa
>> I divide PA by 3386.839 and that gets me to inHg
>>
>> I output this to a file and it comes in to the right range and matches
>> other weather stations around me plus or minus .10 inHg, so I feel like I
>> have things setup correctly.
>>
>> Now this leads me to the error I am getting.
>> The error I get is because the reading is outside the QA range limits..
>> So I have to tried to back into the number some to figure out what is going
>> on....engine: 2017-04-06 23:10:39 CDT (1491538239) LOOP value 'pressure'
>> 85.32306 outside limits (24.0, 34.5)
>>
>> 85.32306... Where the heck did that number come from? Well that
>> is 85.32inHg/.029 = 2942.06896hPa*100 = 294206.8965517Pa
>> Since hPa = mBAR there is no conversion there..
>>
>> The math is wrong in weewx.units?.. but I don't believe that either.. it
>> has to be me messing up the math.. but I am not sure where to go from here
>> to put in a custom conversion into extensions.py... I just have not been
>> able to figure out the code to do so..
>>
>> or I am otherwise all wet..
>>
>> My driver looks like this.. (Expertly written by a very nice MWall)
>>
>> !/usr/bin/python
>>
>> import time
>> import Adafruit_BME280
>> import Adafruit_DHT
>> import weewx.drivers
>> from weewx.units import INHG_PER_MBAR
>>
>> DRIVER_NAME = 'PiHat'
>> DRIVER_VERSION = '0.1'
>>
>> def loader(config_dict, engine):
>> return PiHatDriver(**config_dict[DRIVER_NAME])
>>
>> class PiHatDriver(weewx.drivers.AbstractDevice):
>> def __init__(self, **stn_dict):
>> self._sensor1 =
>> Adafruit_BME280.BME280(mode=Adafruit_BME280.BME280_OSAMPLE_8)
>> self._sensor2 = Adafruit_DHT.AM2302
>> self._pin = 17
>>
>> def genLoopPackets(self):
>> while True:
>> try:
>> packet = dict()
>> packet['dateTime'] = int(time.time() + 0.5)
>> packet['usUnits'] = weewx.METRIC
>> packet['inTemp'] = self._sensor1.read_temperature()
>> packet['pressure'] = self._sensor1.read_pressure() *
>> weewx.units.INHG_PER_MBAR
>> packet['outHumidity'], packet['outTemp'] =
>> Adafruit_DHT.read_retry(self._sensor2, self._pin)
>> yield packet
>> except IOError, e:
>> syslog.syslog(syslog.LOG_ERR, "get data failed: %s" % e)
>> time.sleep(10) # wait 60 seconds before getting next set of
>> data
>>
>>
>>
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "weewx-user" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected] <javascript:>.
>> For more options, visit https://groups.google.com/d/optout.
>>
>
--
You received this message because you are subscribed to the Google Groups
"weewx-user" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
