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1.DHT Sensor Setup
The DHT11 is a low-cost temperature and humidity sensor. It isn’t the fastest sensor around but its cheap price makes it useful for experimenting or projects where you don’t require new readings multiple times a second. The device only requires three connections to the Pi. +3.3v, ground and one GPIO pin.
he 3-pin modules will usually have this resistor included which makes the wiring a bit easier. For this reason I got hold of the module which I could then attach to the Pi with a piece of 3-way Dupont cable.
Different suppliers may wire the module pins differently so check the PCB markings to identify Vcc (+), data or out and Ground (-).
The 3 pins should be connected to the Pi as shown in the table below :
3.3V - + pin of DHT11 module
Gnd - - pin of DHT11 module
Pin17- out pin of DHT11 module
The DHT11 requires a specific protocol to be applied to the data pin. In order to save time trying to implement this yourself it’s far easier to use the Adafruit DHT library.
The library deals with the data that needs to be exchanged with the sensor but it is sensitive to timing issues. The Pi’s operating system may get in the way while performing other tasks so to compensate for this the library requests a number of readings from the device until it gets one that is valid.
First lets clone the Adafruit Library from their repositary:
Open Terminal and paste the following:
git clone https://github.com/adafruit/Adafruit_Python_DHT.git
cd Adafruit_Python_DHT
Then install the library for python:
sudo python setup.py install
Adafruit provides an example script which can be used to check if the sensor is operating correctly
cd ~
cd Adafruit_Python_DHT
cd examples
Then:
python AdafruitDHT.py 11 17
The link for the code is given here
Run using:
python dht11.py
Source: Raspberry-spy.co.uk