text: #!/usr/bin/python
  # Copyright (c) 2014 Adafruit Industries
  # Author: Tony DiCola
  
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  
  # The above copyright notice and this permission notice shall be included in all
  # copies or substantial portions of the Software.
  
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  import sys
  
  import Adafruit_DHT
  
  
  # Parse command line parameters.
  sensor_args = { '11': Adafruit_DHT.DHT11,
                  '22': Adafruit_DHT.DHT22,
                  '2302': Adafruit_DHT.AM2302 }
  if len(sys.argv) == 3 and sys.argv[1] in sensor_args:
      sensor = sensor_args[sys.argv[1]]
      pin = sys.argv[2]
  else:
      print('Usage: sudo ./Adafruit_DHT.py [11|22|2302] <GPIO pin number>')
      print('Example: sudo ./Adafruit_DHT.py 2302 4 - Read from an AM2302 connected to GPIO pin #4')
      sys.exit(1)
  
  # Try to grab a sensor reading.  Use the read_retry method which will retry up
  # to 15 times to get a sensor reading (waiting 2 seconds between each retry).
  humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
  
  # Un-comment the line below to convert the temperature to Fahrenheit.
  # temperature = temperature * 9/5.0 + 32
  
  # Note that sometimes you won't get a reading and
  # the results will be null (because Linux can't
  # guarantee the timing of calls to read the sensor).
  # If this happens try again!
  while True:
  	humidity, temperature = Adafruit_DHT.read_retry(sensor,4)
  	if humidity is not None and temperature is not None:
      		print('Temp={0:0.1f}*  Humidity={1:0.1f}%'.format(temperature, humidity))
  	else:
     		 print('Failed to get reading. Try again!')
    		 sys.exit(1)
  