Part 3 - Get Data from the Internet

So far, this tutorial has taught you how to configure and connect your Pi Pico W to a WiFi network with internet connectivity. Now, you will learn how to receive data (in this case, random facts about cats) over the internet using an API. The code example below uses a so-called REST API, a common way to exchange data over the internet.

Don’t worry if you don’t fully understand every step in this tutorial. By following along and completing the code, you’ll begin to recognize how things like APIs work and how they are used. Even if things remain unclear for now, what you do here will help you to tackle future projects and gain a better understanding over time.

Before beginning, ensure your code.py file is open in Mu Editor and contains the code from part two of the tutorial alongside a valid secrets.py file. Only a few changes are needed to enable your code to request data from an online resource:

1. You must import two more modules to establish socket connections and make HTTP requests:

   # Import modules for establishing socket connections and making HTTP requests
   import ssl
   import adafruit_requests
   

2. Below the import statements, provide the address for the API you want to request data from:

   # URL for the API that will return a random cat fact
   fact_url = "https://meowfacts.herokuapp.com/?lang=eng"
   

3. To enable the requests module to send HTTP requests, you need to set up a socket pool and pass it to the requests session. Here’s how to do it:

   # Create a socket pool and set up requests
   pool = socketpool.SocketPool(wifi.radio)
   requests = adafruit_requests.Session(pool, ssl.create_default_context())
   

4. Replace the existing while True: loop with the following one. During each repetition, the code will open an HTTP connection and send a request to the URL specified in step 2. After receiving a response, the fact contained within is printed to the Serial Monitor before the HTTP connection is closed again.

   while True:
       try:
           print("\nFetching a random cat fact")
           r = requests.get(fact_url)
           fact = r.json()
           print("-" * 40)
           print(fact["data"][0])
           print("-" * 40)
           r.close()
       except Exception as e:
           print("Failed to fetch fact. Error:", e)
   
       time.sleep(10)
   

   The try and except structure prevents your program from crashing if something goes wrong when fetching the fact from the API. The program will continue running and attempt to fetch a new fact again after a short delay.

5. Save your changes and open Mu Editor’s Serial Monitor. If everything went well, your microcontroller will deliver a new cat fact every 10 seconds. Your finished code should look something like this:

   import time
   import wifi 
   import socketpool
   import ssl
   import adafruit_requests
      
   # Get WiFi details from your secrets.py file
   from secrets import secrets
      
   # URL for the API that will return a random cat fact
   fact_url = "https://meowfacts.herokuapp.com/?lang=eng"
         
   # Connect to WiFi using credentials from the secrets file
   wifi.radio.connect(secrets["ssid"], secrets["password"])
         
   # Create a socket pool and set up requests
   pool = socketpool.SocketPool(wifi.radio)
   requests = adafruit_requests.Session(pool, ssl.create_default_context())
      
      
   while True:
       try:
           print("\nFetching a random cat fact")
           r = requests.get(fact_url)
           fact = r.json()
           print("-" * 40)
           print(fact["data"][0])
           print("-" * 40)
           r.close()
       except Exception as e:
           print("Failed to fetch fact. Error:", e)
      
       time.sleep(10)
   

Next Step

You can find a more advanced example of working with an API under Energy Production in the Inspiration section.