rpi_envsens/dht.py

139 lines
5.0 KiB
Python

import logging
import time
try:
from config import APP_NAME as ROOT_LOGGER_NAME
except ImportError:
ROOT_LOGGER_NAME = 'root'
logger = logging.getLogger(ROOT_LOGGER_NAME).getChild(__name__)
from . import background_task
try:
import adafruit_dht
except ImportError:
logger.warning("Could not import adafruit_dht. DEBUG set to True")
DEBUG = True
else:
from . import DEBUG
class dht_22(background_task):
RUN_SLEEP_TIME = 2.0
MIN_REFRESH_RATE = RUN_SLEEP_TIME
KEY_TEMPERATURE = 'temperature'
KEY_HUMIDITY = 'humidity'
KEY_TIME = 'time'
def __init__(self, gpio, data_callback=None):
self.__data_callback__ = data_callback
self.__temp_monitor__ = gradient_monitor(.5, 'DHT Temperature')
self.__hum_monitor__ = gradient_monitor(5, 'DHT Humidity')
self.__monitor__ = dht_22_monitor(300)
# Initial the dht device, with data pin connected to:
if not DEBUG:
self.__dht_device__ = adafruit_dht.DHT22(gpio, use_pulseio=False)
# Initialise background_task
background_task.__init__(self)
def __run__(self):
data = self.__dht_data_transmission__()
if data is not None:
# check data
if self.__temp_monitor__.process(data[self.KEY_TEMPERATURE], data[self.KEY_TIME]) and self.__hum_monitor__.process(data[self.KEY_HUMIDITY], data[self.KEY_TIME]):
#
logger.debug('DHT-Communication: Successfully: %s', repr(data))
self.__monitor__.process(data)
if self.__data_callback__ is not None:
self.__data_callback__(**data)
if self.__monitor__.status():
logger.warning("DHT measurement stopped caused by too many identical values!")
self.close()
else:
logger.warning("DHT-Gradient to high: Ignoring data %s!", repr(data))
def __dht_data_transmission__(self):
if not DEBUG:
while self.__active__:
try:
# Store the values
data = {}
data[self.KEY_TEMPERATURE] = self.__dht_device__.temperature
data[self.KEY_HUMIDITY] = self.__dht_device__.humidity
data[self.KEY_TIME] = int(time.time())
if data[self.KEY_TEMPERATURE] is not None and data[self.KEY_HUMIDITY] is not None:
return data
time.sleep(self.RUN_SLEEP_TIME)
except RuntimeError as error:
# Errors happen fairly often, DHT's are hard to read, just keep going
logger.debug('DHT-Communication: ' + error.args[0])
time.sleep(2.0)
except Exception as error:
self.__dht_device__.exit()
raise error
else:
return {
self.KEY_TEMPERATURE: -17.17,
self.KEY_HUMIDITY: 1.7,
self.KEY_TIME: int(time.time()),
}
class gradient_monitor(object):
def __init__(self, max_gradient):
self.__max_gradient__ = max_gradient
#
self.__last_value__ = None
self.__last_time__ = None
def process(self, value, time):
rv = True
if self.__last_value__ is not None and self.__last_time__ is not None:
gradient = abs((value - self.__last_value__) / (time - self.__last_time__))
if gradient > self.__max_gradient__:
rv = False
self.__last_value__ = value
self.__last_time__ = time
return rv
class dht_22_monitor(object):
def __init__(self, max_const_treshold=250):
self.__max_const_treshold__ = max_const_treshold
self.__fail__ = False
self.__max_const_measurements__ = 0
self.__init_statevars__()
def __init_statevars__(self):
self.__current_const_measurements__ = 0
self.__last_measurements__ = None
def process(self, data):
if self.__last_measurements__ is None:
self.__last_measurements__ = data
else:
data_is_equal = True
for key in [dht_22.KEY_HUMIDITY, dht_22.KEY_TEMPERATURE]:
if data[key] != self.__last_measurements__[key]:
data_is_equal = False
if data_is_equal:
self.__current_const_measurements__ += 1
if self.__current_const_measurements__ > self.__max_const_measurements__:
self.__max_const_measurements__ = self.__current_const_measurements__
else:
self.__init_statevars__()
if self.__max_const_measurements__ > self.__max_const_treshold__:
if not self.__fail__:
logger.warning("DHT measurement values are suspicious constant!")
self.__fail__ = True
def status(self):
if self.__fail__:
self.__fail__ = False
self.__max_const_measurements__ = 0
return True
return False