Setting Up A DHT11 Sensor On Your RASPBERRY PI — The Easy Way
This is the first of a a two-article series, in which I will show you how I set my DHT11 sensor up at home, to collect Temperature and Humidity measurements using Python. In the second one, I will detail how I exposed those measurements as Prometheus metrics and displayed them in this beautiful Grafana dashboard !
The Hardware
Let’s look at the hardware required to make this project.
A Raspberry Pi, which will serve as a controller. We will be running the Python code on it, that will measure Temperature and Humidity through the sensor. I used a Raspberry pi 3B+ here, simply because I had one lying around. Any Raspberry will do fine to follow this tutorial I guess, you will just have to adapt the pinout.
The DHT11 sensor. You can get one for pretty cheap on Amazon, or even cheaper on Aliexpress. I actually had one lying around from an Arduino starter kit I bought a few years back.
The Wiring
Now that we got all our components ready, it’s time to wire things up !
The DHT11 sensor I used has three pins, because it is already soldered with a resistor to a circuit board. Most DHT11 sensors are shipped like this. If yours has 4 pins, your setup will probably very close to this one, but you might have to throw in an additional resistor. Check out your sensor’s manual to get things right !
Back to my example : from left to right, the pins are for data transmission (blue), 5V (red) and ground (black).
I hooked those up like so :
- Red to pin 2 on the Raspberry Pi, which is a 5V Output
- Black to pin 6, Ground
- Blue to pin 7, GPIO 4
Let’s move on to the fun part : the code !
The Code
We will here be writing a bunch of Python code here. Nothing too complicated, so let’s get started.
Preparing the coding environment
First of all, we will be using pipenv to create a virtual environment. To install it, simply run sudo apt install pipenv.
Then, create a folder, say dht11_control and create file named Pipfile in it with the following contents :
The run pipenv install in this folder. This will create a python 3.7 virtual environment, which we will use to run our python script.
Next, we will install the Adafruit Python DHT Sensor library from https://github.com/adafruit/Adafruit_Python_DHT. To do this, you need to :
- Pull the code to the repo :
git clone https://github.com/adafruit/Adafruit_Python_DHT.git - Activate the Python environment :
pipenv shell - Enter the library folder :
cd Adafruit_Python_DHT - Install the library into the environment :
sudo python setup.py install
Now there we go, we have a full environment, all that’s left is to write a couple lines of code.
Writing the script
The script in itself is fairly simple. A couple imports, making a measurement, and printing the output. Here are the contents of main.py.
And there you have it ! All that’s left to do is to run it with pipenv run measure :
$ pipenv run measure
Measured Temp=19.0°C | Hum=46.0%
Measurement took 2.0763556957244873sMagical, it was quite easy in the end, right ? Some very basic code to measure temperature and humidity in your home, but it can be used as a base to fuel your projects !
