This project's code uses the CircuitPython OAuth Library for authentication with Google services. Due to Google's update to the OAuth "authentication flow", the library became incompatible. As a result, this project does not currently work (but may in the future)!
Code
In the MagTag_Google_Calendar folder from the previous step, copy code.py to your CIRCUITPY drive. This should overwrite the authenticator code with the calendar event display code.
# SPDX-FileCopyrightText: 2021 Brent Rubell, written for Adafruit Industries
#
# SPDX-License-Identifier: Unlicense
from os import getenv
import time
import rtc
from adafruit_oauth2 import OAuth2
from adafruit_display_shapes.line import Line
from adafruit_magtag.magtag import MagTag
# Get WiFi details, ensure these are setup in settings.toml
ssid = getenv("CIRCUITPY_WIFI_SSID")
password = getenv("CIRCUITPY_WIFI_PASSWORD")
if None in [ssid, password]:
raise RuntimeError(
"WiFi settings are kept in settings.toml, "
"please add them there. The settings file must contain "
"'CIRCUITPY_WIFI_SSID', 'CIRCUITPY_WIFI_PASSWORD', "
"at a minimum."
)
# Calendar ID
CALENDAR_ID = "YOUR_CALENDAR_ID"
# Maximum amount of events to display
MAX_EVENTS = 3
# Amount of time to wait between refreshing the calendar, in minutes
REFRESH_TIME = 15
# Dict. of month names for pretty-printing the header
MONTHS = {
1: "Jan",
2: "Feb",
3: "Mar",
4: "Apr",
5: "May",
6: "Jun",
7: "Jul",
8: "Aug",
9: "Sep",
10: "Oct",
11: "Nov",
12: "Dec",
}
# Dict. of day names for pretty-printing the header
WEEKDAYS = {
0: "Monday",
1: "Tuesday",
2: "Wednesday",
3: "Thursday",
4: "Friday",
5: "Saturday",
6: "Sunday",
}
# Create a new MagTag object
magtag = MagTag()
r = rtc.RTC()
magtag.network.connect()
# Initialize an OAuth2 object with GCal API scope
scopes = ["https://www.googleapis.com/auth/calendar.readonly"]
google_auth = OAuth2(
magtag.network.requests,
getenv("google_client_id"),
getenv("google_client_secret"),
scopes,
getenv("google_access_token"),
getenv("google_refresh_token"),
)
def get_current_time(time_max=False):
"""Gets local time from Adafruit IO and converts to RFC3339 timestamp."""
# Get local time from Adafruit IO
magtag.get_local_time(getenv("timezone"))
# Format as RFC339 timestamp
cur_time = r.datetime
if time_max: # maximum time to fetch events is midnight (4:59:59UTC)
cur_time_max = time.struct_time(
(
cur_time[0],
cur_time[1],
cur_time[2] + 1,
4,
59,
59,
cur_time[6],
cur_time[7],
cur_time[8],
)
)
cur_time = cur_time_max
cur_time = "{:04d}-{:02d}-{:02d}T{:02d}:{:02d}:{:02d}{:s}".format(
cur_time[0],
cur_time[1],
cur_time[2],
cur_time[3],
cur_time[4],
cur_time[5],
"Z",
)
return cur_time
def get_calendar_events(calendar_id, max_events, time_min):
"""Returns events on a specified calendar.
Response is a list of events ordered by their start date/time in ascending order.
"""
time_max = get_current_time(time_max=True)
print("Fetching calendar events from {0} to {1}".format(time_min, time_max))
headers = {
"Authorization": "Bearer " + google_auth.access_token,
"Accept": "application/json",
"Content-Length": "0",
}
url = (
"https://www.googleapis.com/calendar/v3/calendars/{0}"
"/events?maxResults={1}&timeMin={2}&timeMax={3}&orderBy=startTime"
"&singleEvents=true".format(calendar_id, max_events, time_min, time_max)
)
resp = magtag.network.requests.get(url, headers=headers)
resp_json = resp.json()
if "error" in resp_json:
raise RuntimeError("Error:", resp_json)
resp.close()
# parse the 'items' array so we can iterate over it easier
items = []
resp_items = resp_json["items"]
if not resp_items:
print("No events scheduled for today!")
for event in range(0, len(resp_items)):
items.append(resp_items[event])
return items
def format_datetime(datetime, pretty_date=False):
"""Formats ISO-formatted datetime returned by Google Calendar API into
a struct_time.
:param str datetime: Datetime string returned by Google Calendar API
:return: struct_time
"""
times = datetime.split("T")
the_date = times[0]
the_time = times[1]
year, month, mday = [int(x) for x in the_date.split("-")]
the_time = the_time.split("-")[0]
if "Z" in the_time:
the_time = the_time.split("Z")[0]
hours, minutes, _ = [int(x) for x in the_time.split(":")]
am_pm = "am"
if hours >= 12:
am_pm = "pm"
# convert to 12hr time
if not hours == 12:
hours -= 12
# via https://github.com/micropython/micropython/issues/3087
formatted_time = "{:01d}:{:02d}{:s}".format(hours, minutes, am_pm)
if pretty_date: # return a nice date for header label
formatted_date = "{} {}.{:02d}, {:04d} ".format(
WEEKDAYS[r.datetime[6]], MONTHS[month], mday, year
)
return formatted_date
# Event occurs today, return the time only
return formatted_time
def display_calendar_events(resp_events):
# Display all calendar events
for event_idx in range(len(resp_events)):
event = resp_events[event_idx]
# wrap event name around second line if necessary
event_name = magtag.wrap_nicely(event["summary"], 25)
event_name = "\n".join(event_name[0:2]) # only wrap 2 lines, truncate third..
event_start = event["start"]["dateTime"]
print("-" * 40)
print("Event Description: ", event_name)
print("Event Time:", format_datetime(event_start))
print("-" * 40)
# Generate labels holding event info
magtag.add_text(
text_font=font_event,
text_position=(7, 40 + (event_idx * 35)),
text_color=0x000000,
text=format_datetime(event_start),
)
magtag.add_text(
text_font=font_event,
text_position=(88, 40 + (event_idx * 35)),
text_color=0x000000,
text=event_name,
line_spacing=0.65,
)
# DisplayIO Setup
magtag.set_background(0xFFFFFF)
# Add the header
line_header = Line(0, 30, 320, 30, color=0x000000)
magtag.graphics.root_group.append(line_header)
label_header = magtag.add_text(
text_font="fonts/Arial-18.pcf",
text_position=(5, 15),
text_color=0x000000,
)
# Set up calendar event fonts
font_event = "fonts/Arial-12.pcf"
if not google_auth.refresh_access_token():
raise RuntimeError("Unable to refresh access token - has the token been revoked?")
access_token_obtained = int(time.monotonic())
# check if we need to refresh token
if int(time.monotonic()) - access_token_obtained >= google_auth.access_token_expiration:
print("Access token expired, refreshing...")
if not google_auth.refresh_access_token():
raise RuntimeError(
"Unable to refresh access token - has the token been revoked?"
)
access_token_obtained = int(time.monotonic())
# fetch calendar events!
print("fetching local time...")
now = get_current_time()
# setup header label
magtag.set_text(
format_datetime(now, pretty_date=True), label_header, auto_refresh=False
)
print("fetching calendar events...")
events = get_calendar_events(CALENDAR_ID, MAX_EVENTS, now)
print("displaying events")
display_calendar_events(events)
magtag.graphics.display.refresh()
print("Sleeping for %d minutes" % REFRESH_TIME)
magtag.exit_and_deep_sleep(REFRESH_TIME * 60)
Set Google Calendar ID
Before using this code with your calendar, you'll need to obtain the Google calendar's unique identifier. Navigate to the Google Calendar Settings Page and click the calendar you'd like to display on the MagTag.
Before using this code with your calendar, you'll need to obtain the Google calendar's unique identifier.
Navigate to the Google Calendar Settings Page and click the calendar you'd like to display on the MagTag.
In the code.py file, set CALENDAR_ID using the calendar ID you obtained above.
CALENDAR_ID = "YOUR_CALENDAR_ID"
Every 15 minutes, the MagTag will attempt to fetch your calendar's latest events and display three of them on the screen.
Once an event finishes and the MagTag refreshes, it will be removed from the display.
Change the refresh rate
After fetching and displaying calendar events, the MagTag goes into a deep-sleep mode for 15 minutes. Modify the following line in the code to reflect how long the MagTag will enter the deep sleep mode for, in minutes.
# Amount of time to wait between refreshing the calendar, in minutes REFRESH_TIME = 15
More frequent refresh will use more battery life. If you want the refresh to be quite frequent, consider using a USB C power supply (or connection to USB power from a computer or phone charger brick) to have the MagTag powered all the time.
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Page last edited May 06, 2025
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