Before you can use the Google Calendar API to request events on your calendar, you must first authenticate the device with Google's authentication server.
We've handled this authorization "flow" by creating a CircuitPython library for Google's implementation of OAuth2.0 and an application to run on your device.
Secrets File Setup
Open the secrets.py file on your CircuitPython device using Mu or your favorite text editor. If you don't have one, copy the generic one below. You're going to edit this file to enter your Google API credentials.
-
Change
aio_username
to your Adafruit IO username -
Change
aio_key
to your Adafruit IO active key -
Change
timezone
to"Etc/UTC"
-
Change
google_client_id
to the Google client ID you obtained in the previous step -
Change
google_client_secret
to the Google client ID you obtained in the previous step
Your secrets.py file should look like this:
# This file is where you keep secret settings, passwords, and tokens! # If you put them in the code you risk committing that info or sharing it secrets = { 'ssid' : 'YOUR_SSID', 'password' : 'YOUR_SSID_PASS', 'aio_username': 'YOUR_AIO_USERNAME', 'aio_key': 'YOUR_AIO_KEY', 'timezone' : "Etc/UTC", # http://worldtimeapi.org/timezones 'google_client_id' : 'YOUR_GOOGLE_CLIENT_ID', 'google_client_secret' : 'YOUR_GOOGLE_CLIENT_SECRET' }
Add CircuitPython Code and Project Assets
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the directory MagTag_Google_Calendar/ and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your CIRCUITPY drive.
CIRCUITPY
# SPDX-FileCopyrightText: 2021 Brent Rubell, written for Adafruit Industries # # SPDX-License-Identifier: Unlicense from adafruit_oauth2 import OAuth2 from adafruit_display_text.label import Label from adafruit_bitmap_font import bitmap_font from adafruit_magtag.magtag import Graphics, Network from adafruit_display_shapes.rect import Rect # Add a secrets.py to your filesystem that has a dictionary called secrets with "ssid" and # "password" keys with your WiFi credentials. DO NOT share that file or commit it into Git or other # source control. # pylint: disable=no-name-in-module,wrong-import-order try: from secrets import secrets except ImportError: print("Credentials and tokens are kept in secrets.py, please add them there!") raise network = Network() network.connect() # DisplayIO setup font_small = bitmap_font.load_font("/fonts/Arial-12.pcf") font_large = bitmap_font.load_font("/fonts/Arial-14.pcf") graphics = Graphics(auto_refresh=False) display = graphics.display background = Rect(0, 0, 296, 128, fill=0xFFFFFF) graphics.splash.append(background) label_overview_text = Label( font_large, x=0, y=10, line_spacing=0.75, color=0x000000, text="Authorize this device with Google:", ) graphics.splash.append(label_overview_text) label_verification_url = Label(font_small, x=0, y=40, line_spacing=0.75, color=0x000000) graphics.splash.append(label_verification_url) label_user_code = Label(font_small, x=0, y=80, color=0x000000, line_spacing=0.75) graphics.splash.append(label_user_code) label_qr_code = Label( font_small, x=0, y=100, color=0x000000, text="Or scan the QR code:" ) graphics.splash.append(label_qr_code) # Set scope(s) of access required by the API you're using scopes = ["https://www.googleapis.com/auth/calendar.readonly"] # Initialize an OAuth2 object google_auth = OAuth2( network.requests, secrets["google_client_id"], secrets["google_client_secret"], scopes, ) # Request device and user codes # https://developers.google.com/identity/protocols/oauth2/limited-input-device#step-1:-request-device-and-user-codes google_auth.request_codes() # Display user code and verification url # NOTE: If you are displaying this on a screen, ensure the text label fields are # long enough to handle the user_code and verification_url. # Details in link below: # https://developers.google.com/identity/protocols/oauth2/limited-input-device#displayingthecode print( "1) Navigate to the following URL in a web browser:", google_auth.verification_url ) print("2) Enter the following code:", google_auth.user_code) label_verification_url.text = ( "1. On your computer or mobile device,\ngo to %s" % google_auth.verification_url ) label_user_code.text = "2. Enter code: %s" % google_auth.user_code graphics.qrcode(google_auth.verification_url.encode(), qr_size=2, x=240, y=70) graphics.display.root_group = graphics.splash display.refresh() # Poll Google's authorization server print("Waiting for browser authorization...") if not google_auth.wait_for_authorization(): raise RuntimeError("Timed out waiting for browser response!") print("Successfully Authenticated with Google!") print("Add the following lines to your secrets.py file:") print("\t'google_access_token' " + ":" + " '%s'," % google_auth.access_token) print("\t'google_refresh_token' " + ":" + " '%s'" % google_auth.refresh_token) graphics.splash.pop() graphics.splash.pop() graphics.splash.pop() label_overview_text.text = "Successfully Authenticated!" label_verification_url.text = ( "Check the REPL for tokens to add\n\tto your secrets.py file" ) display.refresh()
Authenticator Code Usage
On your CIRCUITPY drive, rename authenticator.py to code.py. Then, open the CircuitPython REPL using Mu or another serial monitor.
Your CircuitPython device should boot into the Google Authenticator code and display a code and URL.
Navigate to the Google Device page and enter the code you see on your device.
Click Next
Select the Google Account you'd like to use with the calendar viewer.
- We are using the
https://www.googleapis.com/auth/calendar.readonly
scope which will gives an application read-only access to your calendar events.
Since Google has not formally verified the application you created in the previous step, you'll be greeted with a warning.
- Click Advanced
- Then, Click the Go to {your application name} link
Finally, a dialog will appear displaying the application's requested permissions.
Click Allow.
You'll be presented with a dialog telling you the device has been authenticated.
After 5 seconds, the CircuitPython REPL should display a google_access_token
and google_refresh_token
.
Copy and paste these lines into the secrets.py file.
Your secrets.py file should look like this:
# This file is where you keep secret settings, passwords, and tokens! # If you put them in the code you risk committing that info or sharing it secrets = { 'ssid' : 'YOUR_SSID', 'password' : 'YOUR_SSID_PASS', 'aio_username': 'YOUR_AIO_USERNAME', 'aio_key': 'YOUR_AIO_KEY' 'timezone' : "Etc/UTC", # http://worldtimeapi.org/timezones 'google_client_id' : 'YOUR_GOOGLE_CLIENT_ID', 'google_client_secret' : 'YOUR_GOOGLE_CLIENT_SECRET', 'google_access_token' : 'YOUR_GOOGLE_ACCESS_TOKEN', 'google_refresh_token' : 'YOUR_GOOGLE_REFRESH_TOKEN' }
Now that your device is authorized to make requests to the Google Calendar API, let's use it to fetch calendar events!
Page last edited January 22, 2025
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