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
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