Weatherg : Lecture des capteurs DHT22 et BMP185 en Python

Installer les dépendances :

Pour le DHT22, cloner la bibliothèque fourni par Adafruit et installer là :

$ git clone https://github.com/adafruit/Adafruit_Python_DHT.git
$ cd Adafuit_Python_DHT && sudo python setup.py install

Pour tester l’installation et votre câblage :

sudo examples/Adafruit_DHT 22 4

Ici 22  correspond au DHT22, pour le DHT11, utiliser 11 . Le 4 correspond à la broche GPIO #4 du Raspberry PI.

Recommencer pour le BMP185, ce dernier est câblé sur les broche I2C.

$ git clone https://github.com/adafruit/Adafruit_Python_BMP.git
$ cd Adafruit_Python_BMP && sudo python setup.py install

Enfin un petit test :

sudo examples/simpletest.py

Exemple de code

# Adafruit library
import Adafruit_DHT
import Adafruit_BMP.BMP085 as BMP085

# sensor config
DHT_SENSOR = 22
PIN = 4

# 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(DHT_SENSOR, PIN)
#
#
# Default constructor will pick a default I2C bus.
#
# For the Raspberry Pi this means you should hook up to the only exposed I2C bus
# from the main GPIO header and the library will figure out the bus number based
# on the Pi's revision.
#
# For the Beaglebone Black the library will assume bus 1 by default, which is
# exposed with SCL = P9_19 and SDA = P9_20.
#
# Can enable debug output by uncommenting:
#import logging
#logging.basicConfig(level=logging.DEBUG)
bmp_sensor = BMP085.BMP085()

# Optionally you can override the bus number:
#sensor = BMP085.BMP085(busnum=2)

# You can also optionally change the BMP085 mode to one of BMP085_ULTRALOWPOWER,
# BMP085_STANDARD, BMP085_HIGHRES, or BMP085_ULTRAHIGHRES.  See the BMP085
# datasheet for more details on the meanings of each mode (accuracy and power
# consumption are primarily the differences).  The default mode is STANDARD.
sensor = BMP085.BMP085(mode=BMP085.BMP085_ULTRAHIGHRES)

bmp_temp = bmp_sensor.read_temperature()
bmp_pressure = bmp_sensor.read_pressure()
bmp_altitude = bmp_sensor.read_altitude()
bmp_sealevel_pressure = bmp_sensor.read_sealevel_pressure()

print 'BMP measures'
print 'Temp = {0:0.2f} *C'.format(bmp_temp)
print 'Pressure = {0:0.2f} Pa'.format(bmp_pressure)
print 'Altitude = {0:0.2f} m'.format(bmp_altitude)
print 'Sealevel Pressure = {0:0.2f} Pa'.format(bmp_sealevel_pressure)


print 'DHT ' + str(DHT_SENSOR) + ' measures'
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)

Sources :

A venir