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#!/usr/bin/python
# vim: set fileencoding=utf-8 :
#
# Copyright 2014 Guido Guenther <agx@sigxcpu.org>
#
# Licesnse: GPLv3
#
# A munin plugin to measure temperature and humidity
#
#%# capabilities=autoconf
#%# family=contrib
import os
import sys
import math
# Useful to run from within the source tree
exe = os.path.abspath(os.path.dirname(os.path.realpath(sys.argv[0])))
dev_path='%s/Adafruit_Python_DHT/build/lib.linux-armv6l-2.7/' % (exe, )
if os.path.exists(dev_path):
sys.path.insert(0, dev_path)
import Adafruit_DHT
sensortype = os.getenv('sensor', 'AM2302')
pin = os.getenv('pin', 4)
def print_config():
where = os.getenv('where')
if where is None:
where = sys.argv[0].split('_', 1)[1]
print """graph_title Humidity and Temperature in %(where)s
graph_category heating
graph_info Show temperature, humidity and dewpoint in %(where)s using a %(sensortype)s
temp.label Temperature
temp.type GAUGE
temp.max 100
temp.min -50
hum.label Humidity
hum.type GAUGE
hum.max 100
hum.min 0
hum.critical 60
hum.warning 50
dp.label Dewpoint
dp.type GAUGE
""" % dict(sensortype=sensortype, where=where)
K2 = 17.5043
K3 = 241.2
def calc_dewpoint(temp, hum):
"""
See https://de.wikipedia.org/wiki/Taupunkt
>>> calc_dewpoint(20, 100)
20.0
"""
phi = hum / 100.0
theta = temp
lnphi = math.log(phi)
z = ((K2 * theta) / (K3 + theta)) + lnphi
n = ((K2 * K3) / (K3 + theta)) - lnphi
return K3 * (z/n)
def fetch_values():
sensor = eval('Adafruit_DHT.' + sensortype)
hum, temp = Adafruit_DHT.read_retry(sensor, pin)
dp = calc_dewpoint(temp, hum)
print "temp.value %f" % temp
print "hum.value %f" % hum
print "dp.value %f" % dp
def main(args):
if len(args) > 1:
if args[1] in [ 'autoconf', 'detect' ]:
try:
fetch_raw()
print "yes"
return 0
except:
print "no"
return 1
elif args[1] == 'config':
try:
print_config()
except Exception as e:
print >>sys.stderr, "Failed to fetch config: '%s'" % e
return 1
return 0
try:
fetch_values()
except Exception as e:
print >>sys.stderr, "Failed to fetch values: '%s'" % e
return 1
return 0
if __name__ == "__main__":
sys.exit(main(sys.argv))
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