Reading data from an atmospheric sensor

Overview

In this lesson we are going to write code that will allow us to download data from an atmospheric sensor.
The sensor will give us data on temperature, atmospheric pressure, battery voltage and signal strength.
We will use the python language to get this data.
Once we have data we can do other amazing things such as save the data and even graph the data.
Environmental data is very important because it allows us to monitor the environment we live in more closely.

Sensors are now commonly connected to the internet.
This has given rise to the term – The Internet of Things.
If a sensor is connected to the internet then it will often have a URL (Universal Resource Locator) to allow us to interact with the sensor.
One common interaction is to be able to see or download data collected by the sensor.
To get data from a sensor we need to import the requests library in python.
In this lesson we will download some data from an atmospheric sensor.
The sensor data includes temperature, air pressure, sensor battery voltage and signal strength.
In this example we write a python3 program to download sensor data using the requests library.
The data will be presented in the python Shell.

From the Raspberry Pi main menu drop down select Programming > Python3 (IDLE).
This will open up the Python Shell.
From the File drop down menu select New File.
This will open up a new file Editor Window.
We are going to name the file atm_sensor_get.py

We can add notes within our program called Comments.
Comments always start with a # (hash symbol) at the start of the line.
Computers ignore comments because comments are only read by humans.
To signal that the text has been commented out, the text colour will change to red.
In this example the comment is the file name.

Navigate to your working directory and then save the file as atm_sensor_get.py
In Linux we never use names that include spaces.
Replace spaces with either the _ (underline) symbol or the – (hyphen) symbol.

Enter the following lines of request to request data from the atmospheric sensor.
The key items in the code are described:
- import requests – this statement imports a python library so that the python program can get data from the internet.
- r = requests.get(URL) – this statement gets the data from a specified URL and stores the result in the variable object named r. URL is short for Uniform Resource Location, also known as a web address.
- print(r) – this statement prints a code that determines if the request was successful or not.
Save and the Run the program.