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.

Learning Objectives

• Learn how to use the requests library in python to get data from a URL
• Learn how to interpret data presented in the JSON format
• Learn how to process data in python so that it can be saved in variables

Requesting new data from a sensor URL in Python

• 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.

Create a new file in python named atm_sensor_get.py

• 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

• As a placeholder we can add this file name within our new file.
• We will however add a # (hash) in front of the name so that we comment it out.
• When we comment out text in a file the computer will ignore it.
• The line will only be useful for humans.
• To signal that the text has been commented out, the text colour will change to red.