The Covid Tracking Project (https://covidtracking.com) tracks all US state data and collates it into one report. This project for MagTag wakes up once a day at 8pm, about a half hour after the data is posted daily, and displays the latest data report.

In between check-ins the MagTag goes into a deep sleep mode so it will run for many weeks on a charge

Parts Required

You'll want a MagTag + battery, and magnetic feet to attach it to your fridge or other metallic surface

The Adafruit MagTag combines the new ESP32-S2 wireless module and a 2.9" grayscale E-Ink display to make a low-power IoT display that can show data on its screen...
Out of Stock

You can also get the parts separately

The Adafruit MagTag combines the new ESP32-S2 wireless module and a 2.9" grayscale E-Ink display to make a low-power IoT display that can show data on its screen even when power...
Out of Stock
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
$6.95
In Stock
Got a glorious RGB Matrix project you want to mount and display in your workspace or home? If you have one of the matrix panels listed below, you'll need a pack of these...
$2.50
In Stock

Also needed:

  • WiFi network (802.11 b/g/n)
  • A desktop or laptop computer is required for initial setup: any text editor will suffice
  • An Adafruit IO account. If you’ve previously purchased from Adafruit and created an account, this is automagic (and free)!

CircuitPython is a derivative of MicroPython designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the CIRCUITPY drive to iterate.

Set Up CircuitPython

Follow the steps to get CircuitPython installed on your MagTag.

Click the link above and download the latest .BIN and .UF2 file

(depending on how you program the ESP32S2 board you may need one or the other, might as well get both)

Download and save it to your desktop (or wherever is handy).

Plug your MagTag into your computer using a known-good USB cable.

A lot of people end up using charge-only USB cables and it is very frustrating! So make sure you have a USB cable you know is good for data sync.

Option 1 - Load with UF2 Bootloader

This is by far the easiest way to load CircuitPython. However it requires your board has the UF2 bootloader installed. Some early boards do not (we hadn't written UF2 yet!) - in which case you can load using the built in ROM bootloader.

Still, try this first!

Try Launching UF2 Bootloader

Loading CircuitPython by drag-n-drop UF2 bootloader is the easier way and we recommend it. If you have a MagTag where the front of the board is black, your MagTag came with UF2 already on it.

Launch UF2 by double-clicking the Reset button (the one next to the USB C port). You may have to try a few times to get the timing right.

If the UF2 bootloader is installed, you will see a new disk drive appear called MAGTAGBOOT

Copy the UF2 file you downloaded at the first step of this tutorial onto the MAGTAGBOOT drive

If you're using Windows and you get an error at the end of the file copy that says Error from the file copy, Error 0x800701B1: A device which does not exist was specified. You can ignore this error, the bootloader sometimes disconnects without telling Windows, the install completed just fine and you can continue. If its really annoying, you can also upgrade the bootloader (the latest version of the UF2 bootloader fixes this warning)

Your board should auto-reset into CircuitPython, or you may need to press reset. A CIRCUITPY drive will appear. You're done! Go to the next pages.

Option 2 - Use esptool to load BIN file

If you have an original MagTag with while soldermask on the front, we didn't have UF2 written for the ESP32S2 yet so it will not come with the UF2 bootloader.

You can upload with esptool to the ROM (hardware) bootloader instead!

Follow the initial steps found in the Run esptool and check connection section of the ROM Bootloader page to verify your environment is set up, your board is successfully connected, and which port it's using.

In the final command to write a binary file to the board, replace the port with your port, and replace "firmware.bin" with the the file you downloaded above.

The output should look something like the output in the image.

Press reset to exit the bootloader.

Your CIRCUITPY drive should appear!

You're all set! Go to the next pages.

Option 3 - Use Chrome Browser To Upload BIN file

If for some reason you cannot get esptool to run, you can always try using the Chrome-browser version of esptool we have written. This is handy if you don't have Python on your computer, or something is really weird with your setup that makes esptool not run (which happens sometimes and isn't worth debugging!) You can follow along on the Web Serial ESPTool page and either load the UF2 bootloader and then come back to Option 1 on this page, or you can download the CircuitPython BIN file directly using the tool in the same manner as the bootloader.

To use the internet-connectivity built into your ESP32-S2 with CircuitPython, you must first install a number of libraries. This page covers that process.

Adafruit CircuitPython Library Bundle

Download the Adafruit CircuitPython Bundle. You can find the latest release here:

Download the adafruit-circuitpython-bundle-version-mpy-*.zip bundle zip file, and unzip a folder of the same name. Inside you'll find a lib folder. The entire collection of libraries is too large to fit on the CIRCUITPY drive. Instead, add each library as you need it, this will reduce the space usage but you'll need to put in a little more effort.

At a minimum we recommend the following libraries, in fact we more than recommend. They're basically required. So grab them and install them into CIRCUITPY/lib now!

  • adafruit_requests.mpy - A requests-like library for HTTP commands.
  • neopixel.mpy - Helper library to use NeoPixel LEDs, often built into the boards so they're great for quick feedback

Once you have added those files, please continue to the next page to set up and test Internet connectivity

Once you have CircuitPython installed and the minimum libraries installed we can get your board connected to the Internet. 

To get connected, you will need to start by creating a secrets.py file.

Secrets File

We expect people to share tons of projects as they build CircuitPython WiFi widgets. What we want to avoid is people accidentally sharing their passwords or secret tokens and API keys. So, we designed all our examples to use a secrets.py file, that is in your CIRCUITPY drive, to hold secret/private/custom data. That way you can share your main project without worrying about accidentally sharing private stuff.

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' : 'home_wifi_network',
    'password' : 'wifi_password',
    'aio_username' : 'my_adafruit_io_username',
    'aio_key' : 'my_adafruit_io_key',
    'timezone' : "America/New_York", # http://worldtimeapi.org/timezones
    }

Copy and paste that text/code into a file called secrets.py and save it to your CIRCUITPY folder like so:

Inside is a python dictionary named secrets with a line for each entry. Each entry has an entry name (say 'ssid') and then a colon to separate it from the entry key 'home ssid' and finally a comma ,

At a minimum you'll need to adjust the ssid and password for your local WiFi setup so do that now!

As you make projects you may need more tokens and keys, just add them one line at a time. See for example other tokens such as one for accessing github or the hackaday API. Other non-secret data like your timezone can also go here, just cause its called secrets doesn't mean you can't have general customization data in there!

For the correct time zone string, look at http://worldtimeapi.org/timezones and remember that if your city is not listed, look for a city in the same time zone, for example Boston, New York, Philadelphia, Washington DC, and Miami are all on the same time as New York.

Of course, don't share your secrets.py - keep that out of GitHub, Discord or other project-sharing sites.

Don't share your secrets.py file, it has your passwords and API keys in it!

Connect to WiFi

OK now you have your secrets setup - you can connect to the Internet using the Requests module.

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle. Our introduction guide has a great page on how to install the library bundle.

  • adafruit_requests
  • neopixel

Before continuing make sure your board's CIRCUITPY/lib folder or root filesystem has the above files copied over.

Once that's done, load up the following example using Mu or your favorite editor:

import ipaddress
import ssl
import wifi
import socketpool
import adafruit_requests

# URLs to fetch from
TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_QUOTES_URL = "https://www.adafruit.com/api/quotes.php"
JSON_STARS_URL = "https://api.github.com/repos/adafruit/circuitpython"

# Get wifi details and more from a secrets.py file
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

print("ESP32-S2 WebClient Test")

print("My MAC addr:", [hex(i) for i in wifi.radio.mac_address])

print("Available WiFi networks:")
for network in wifi.radio.start_scanning_networks():
    print("\t%s\t\tRSSI: %d\tChannel: %d" % (str(network.ssid, "utf-8"),
            network.rssi, network.channel))
wifi.radio.stop_scanning_networks()

print("Connecting to %s"%secrets["ssid"])
wifi.radio.connect(secrets["ssid"], secrets["password"])
print("Connected to %s!"%secrets["ssid"])
print("My IP address is", wifi.radio.ipv4_address)

ipv4 = ipaddress.ip_address("8.8.4.4")
print("Ping google.com: %f ms" % (wifi.radio.ping(ipv4)*1000))

pool = socketpool.SocketPool(wifi.radio)
requests = adafruit_requests.Session(pool, ssl.create_default_context())

print("Fetching text from", TEXT_URL)
response = requests.get(TEXT_URL)
print("-" * 40)
print(response.text)
print("-" * 40)

print("Fetching json from", JSON_QUOTES_URL)
response = requests.get(JSON_QUOTES_URL)
print("-" * 40)
print(response.json())
print("-" * 40)

print()

print("Fetching and parsing json from", JSON_STARS_URL)
response = requests.get(JSON_STARS_URL)
print("-" * 40)
print("CircuitPython GitHub Stars", response.json()["stargazers_count"])
print("-" * 40)

print("done")

And save it to your board. Make sure the file is named code.py.

Open up your REPL, you should see something like the following:

In order, the example code...

Checks the ESP32-S2's MAC address.

print("My MAC addr:", [hex(i) for i in wifi.radio.mac_address])

Performs a scan of all access points and prints out the access point's name (SSID), signal strength (RSSI), and channel.

print("Avaliable WiFi networks:")
for network in wifi.radio.start_scanning_networks():
    print("\t%s\t\tRSSI: %d\tChannel: %d" % (str(network.ssid, "utf-8"),
            network.rssi, network.channel))
wifi.radio.stop_scanning_networks()

Connects to the access point you defined in the secrets.py file, prints out its local IP address, and attempts to ping google.com to check its network connectivity. 

print("Connecting to %s"%secrets["ssid"])
wifi.radio.connect(secrets["ssid"], secrets["password"])
print(print("Connected to %s!"%secrets["ssid"]))
print("My IP address is", wifi.radio.ipv4_address)

ipv4 = ipaddress.ip_address("8.8.4.4")
print("Ping google.com: %f ms" % wifi.radio.ping(ipv4))

The code creates a socketpool using the wifi radio's available sockets. This is performed so we don't need to re-use sockets. Then, it initializes a a new instance of the requests interface - which makes getting data from the internet really really easy.

pool = socketpool.SocketPool(wifi.radio)
requests = adafruit_requests.Session(pool, ssl.create_default_context())

To read in plain-text from a web URL, call requests.get - you may pass in either a http, or a https url for SSL connectivity. 

print("Fetching text from", TEXT_URL)
response = requests.get(TEXT_URL)
print("-" * 40)
print(response.text)
print("-" * 40)

Requests can also display a JSON-formatted response from a web URL using a call to requests.get

print("Fetching json from", JSON_QUOTES_URL)
response = requests.get(JSON_QUOTES_URL)
print("-" * 40)
print(response.json())
print("-" * 40)

Finally, you can fetch and parse a JSON URL using requests.get. This code snippet obtains the stargazers_count field from a call to the GitHub API.

print("Fetching and parsing json from", JSON_STARS_URL)
response = requests.get(JSON_STARS_URL)
print("-" * 40)
print("CircuitPython GitHub Stars", response.json()["stargazers_count"])
print("-" * 40)

OK you now have your ESP32-S2 board set up with a proper secrets.py file and can connect over the Internet. If not, check that your secrets.py file has the right ssid and password and retrace your steps until you get the Internet connectivity working!

A very common need for projects is to know the current date and time. Especially when you want to deep sleep until an event, or you want to change your display based on what day, time, date, etc. it is

Determining the correct local time is really really hard. There are various time zones, Daylight Savings dates, leap seconds, etc. Trying to get NTP time and then back-calculating what the local time is, is extraordinarily hard on a microcontroller just isn't worth the effort and it will get out of sync as laws change anyways.

For that reason, we have the free adafruit.io time service. Free for anyone, with a free adafruit.io account. You do need an account because we have to keep accidentally mis-programmed-board from overwhelming adafruit.io and lock them out temporarily. Again, it's free!

There are other services like WorldTimeAPI, but we don't use those for our guides because they are nice people and we don't want to accidentally overload their site. Also, there's a chance it may eventually go down or also require an account.

Step 1) Make an Adafruit account

It's free! Visit https://accounts.adafruit.com/ to register and make an account if you do not already have one

Step 2) Sign into Adafruit IO

Head over to io.adafruit.com and click Sign In to log into IO using your Adafruit account. It's free and fast to join.

Step 3) Get your Adafruit IO Key

Click on My Key in the top bar

You will get a popup with your Username and Key (In this screenshot, we've covered it with red blocks)

Go to your secrets.py file on your CIRCUITPY drive and add three lines for aio_username, aio_key and timezone so you get something like the following:

# 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' : 'home_wifi_network',
    'password' : 'wifi_password',
    'aio_username' : 'my_adafruit_io_username',
    'aio_key' : 'my_adafruit_io_key',
    'timezone' : "America/New_York", # http://worldtimeapi.org/timezones
    }

The timezone is optional, if you don't have that entry, adafruit.io will guess your timezone based on geographic IP address lookup. You can visit http://worldtimeapi.org/timezones to see all the time zones available (even though we do not use worldtimeapi for time-keeping we do use the same time zone table)

Step 4) Upload Test Python Code

This code is like the Internet Test code from before, but this time it will connect to adafruit.io and get the local time

import ipaddress
import ssl
import wifi
import socketpool
import adafruit_requests
import secrets


TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_QUOTES_URL = "https://www.adafruit.com/api/quotes.php"
JSON_STARS_URL = "https://api.github.com/repos/adafruit/circuitpython"

# Get wifi details and more from a secrets.py file
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

# Get our username, key and desired timezone
aio_username = secrets["aio_username"]
aio_key = secrets["aio_key"]
location = secrets.get("timezone", None)
TIME_URL = "https://io.adafruit.com/api/v2/%s/integrations/time/strftime?x-aio-key=%s" % (aio_username, aio_key)
TIME_URL += "&fmt=%25Y-%25m-%25d+%25H%3A%25M%3A%25S.%25L+%25j+%25u+%25z+%25Z"

print("ESP32-S2 Adafruit IO Time test")

print("My MAC addr:", [hex(i) for i in wifi.radio.mac_address])

print("Available WiFi networks:")
for network in wifi.radio.start_scanning_networks():
    print("\t%s\t\tRSSI: %d\tChannel: %d" % (str(network.ssid, "utf-8"),
            network.rssi, network.channel))
wifi.radio.stop_scanning_networks()

print("Connecting to %s"%secrets["ssid"])
wifi.radio.connect(secrets["ssid"], secrets["password"])
print("Connected to %s!"%secrets["ssid"])
print("My IP address is", wifi.radio.ipv4_address)

ipv4 = ipaddress.ip_address("8.8.4.4")
print("Ping google.com: %f ms" % wifi.radio.ping(ipv4))

pool = socketpool.SocketPool(wifi.radio)
requests = adafruit_requests.Session(pool, ssl.create_default_context())

print("Fetching text from", TIME_URL)
response = requests.get(TIME_URL)
print("-" * 40)
print(response.text)
print("-" * 40)

After running this, you will see something like the below text. We have blocked out the part with the secret username and key data!

Note at the end you will get the date, time, and your timezone! If so, you have correctly configured your secrets.py and can continue to the next steps!

To use all the amazing features of your MagTag with CircuitPython, you must first install a number of libraries. This page covers that process.

Get Latest Adafruit CircuitPython Bundle

Download the Adafruit CircuitPython Library Bundle. You can find the latest release here:

Download the adafruit-circuitpython-bundle-version-mpy-*.zip bundle zip file, and unzip a folder of the same name. Inside you'll find a lib folder. The entire collection of libraries is too large to fit on the CIRCUITPY drive. Therefore, you'll need to copy the necessary libraries to your board individually.

At a minimum, the following libraries are required. Copy the following folders or .mpy files to the lib folder on your CIRCUITPY drive. If the library is a folder, copy the entire folder to the lib folder on your board.

Library folders (copy the whole folder over to lib):

  • adafruit_magtag - This is a helper library designed for using all of the features of the MagTag, including networking, buttons, NeoPixels, etc.
  • adafruit_portalbase - This library is the base library that adafruit_magtag is built on top of.
  • adafruit_bitmap_font - There is fancy font support, and it's easy to make new fonts. This library reads and parses font files.
  • adafruit_display_text - This library displays text on the screen.
  • adafruit_io - This library helps connect the MagTag to our free data logging and viewing service

Library files:

  • adafruit_requests.mpy - This library allows us to perform HTTP requests and get responses back from servers. GET/POST/PUT/PATCH - they're all in here!
  • adafruit_fakerequests.mpy  - This library allows you to create fake HTTP requests by using local files.
  • adafruit_miniqr.mpy  - QR creation library lets us add easy-to-scan 2D barcodes to the E-Ink display
  • neopixel.mpy - This library is used to control the onboard NeoPixels.
  • simpleio.mpy - This library is used for tone generation.

Secrets

Even if you aren't planning to go online with your MagTag, you'll need to have a secrets.py file in the root directory (top level) of your CIRCUITPY drive. If you do not intend to connect to wireless, it does not need to have valid data in it. Here's more info on the secrets.py file.

Download and Install Code + Font

Make sure you've installed CircuitPython and all the required libraries, as well as set up adafruit.io API access to be able to get the local time on the previous pages.

Once ready, click the Download: Project Zip File link below in the code window to get a zip file with all the files needed for the project. Copy code.py from the zip file and place on the CIRCUITPY drive along with the fonts/ directory that contains the arial-bold-12.pcf font

# SPDX-FileCopyrightText: 2020 ladyada, written for Adafruit Industries
#
# SPDX-License-Identifier: Unlicense
import time
import alarm
import supervisor
import alarm
from adafruit_magtag.magtag import MagTag

# Change this to the hour you want to check the data at, for us its 8pm
# local time (eastern), which is 20:00 hrs
DAILY_UPDATE_HOUR = 20

# Set up where we'll be fetching data from
DATA_SOURCE = "https://api.covidtracking.com/v1/us/current.json"
DATE_LOCATION = [0, 'dateChecked']
NEWPOS_LOCATION = [0, 'positiveIncrease']
CURRHOSP_LOCATION = [0, 'hospitalizedCurrently']
NEWHOSP_LOCATION = [0, 'hospitalizedIncrease']
ALLDEATH_LOCATION = [0, 'death']
NEWDEATH_LOCATION = [0, 'deathIncrease']

magtag = MagTag(
    url=DATA_SOURCE,
    json_path=(DATE_LOCATION, NEWPOS_LOCATION,
               CURRHOSP_LOCATION, NEWHOSP_LOCATION,
               ALLDEATH_LOCATION, NEWDEATH_LOCATION),
)


# Date stamp of info
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 15),
    text_transform=lambda x: "Date: {}".format(x[0:10]),
)
# Positive increase
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 35),
    text_transform=lambda x: "New positive:   {:,}".format(x),
)
# Curr hospitalized
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 55),
    text_transform=lambda x: "Current Hospital:   {:,}".format(x),
)
# Change in hospitalized
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 75),
    text_transform=lambda x: "Change in Hospital:   {:,}".format(x),
)
# All deaths
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 95),
    text_transform=lambda x: "Total deaths:   {:,}".format(x),
)
# new deaths
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 115),
    text_transform=lambda x: "New deaths:   {:,}".format(x),
)

# updated time
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(245, 30),
    line_spacing=0.75,
    is_data=False
)

magtag.graphics.qrcode(b"https://covidtracking.com/data",
                       qr_size=2, x=240, y=70)

magtag.peripherals.neopixels.brightness = 0.1
magtag.peripherals.neopixel_disable = False # turn on lights
magtag.peripherals.neopixels.fill(0x0F0000) # red!

magtag.get_local_time()
try:
    now = time.localtime()
    print("Now: ", now)

    # display the current time since its the last-update
    updated_at = "%d/%d\n%d:%02d" % now[1:5]
    magtag.set_text(updated_at, 6, False)

    # get data from the Covid Tracking Project
    value = magtag.fetch()
    print("Response is", value)

    # OK we're done!
    magtag.peripherals.neopixels.fill(0x000F00) # greten
except (ValueError, RuntimeError) as e:
    print("Some error occured, trying again later -", e)

time.sleep(2) # let screen finish updating

# we only wanna wake up once a day, around the event update time:
event_time = time.struct_time((now[0], now[1], now[2],
                               DAILY_UPDATE_HOUR, 0, 0,
                               -1, -1, now[8]))
# how long is that from now?
remaining = time.mktime(event_time) - time.mktime(now)
if remaining < 0:             # ah its aready happened today...
    remaining += 24 * 60 * 60 # wrap around to the next day
remaining_hrs = remaining // 3660
remaining_min = (remaining % 3600) // 60
print("Gonna zzz for %d hours, %d minutes" % (remaining_hrs, remaining_min))

# Turn it all off and go to bed till the next update time
magtag.exit_and_deep_sleep(remaining)

Code Walkthrough

Thankfully, the Covid Tracking Project folks made a free, easy-to-use JSON API endpoint that you can easily query with the MagTag to get the current stats at https://api.covidtracking.com/v1/us/current.json You can click on it right from your browser to see the current data and you'll get something like this

[
  {
    "date": 20201210,
    "states": 56,
    "positive": 15360841,
    "negative": 167187901,
    "pending": 12409,
    "hospitalizedCurrently": 107258,
    "hospitalizedCumulative": 603554,
    "inIcuCurrently": 21023,
    "inIcuCumulative": 32919,
    "onVentilatorCurrently": 7442,
    "onVentilatorCumulative": 3394,
    "recovered": 5985047,
    "dateChecked": "2020-12-10T24:00:00Z",
    "death": 283555,
    "hospitalized": 603554,
    "totalTestResults": 213015816,
    "lastModified": "2020-12-10T24:00:00Z",
    "total": 0,
    "posNeg": 0,
    "deathIncrease": 3067,
    "hospitalizedIncrease": 4335,
    "negativeIncrease": 1339749,
    "positiveIncrease": 215669,
    "totalTestResultsIncrease": 1954686,
    "hash": "27226d54c5463327b7303d241b4085e06d976068"
  }
]

These are pretty self-explanatory, note that date is not the current date, but the date at which the data was collected. We'll be displaying positiveIncrease, hospitalizedCurrently, hospitalizedIncrease, death and deathIncrease but of course the display can be customized.

Daily Update Time

The report from CTP only gets updated once a day, so its a good project for MagTag to deep-sleep between reads. That way it can last many weeks on a charge. Data is updated at around 7:30pm eastern, which is our local time. To account for any delay in reporting, we will check every night at 8pm eastern. 8pm eastern in 24-hour-time numbers is 20:00, so we put in 20 as the daily-check-hour. If you're in another timezone, figure out what local time that translates to if you'd like to catch the report right after its posted.

# Change this to the hour you want to check the data at, for us its 8pm
# local time (eastern), which is 20:00 hrs
DAILY_UPDATE_HOUR = 20

Text Transforms with lambdas

The numbers we get from CTP need to have some text before them to explain what they are, for example "New Positive" before the number we extract from the json API as "negativeIncrease": 1339749

To do that we use an 'anonymous function' (a.k.a. a lambda) which we can code in-line that will take the string extracted "1339749" and preface it with the text "New positive:" as well as putting commas in between the digit groupings.

Thats what this line does:

text_transform=lambda x: "New positive: {:,}".format(x)

lambda x: is basically the same as making a new function with:

def anonymous_function(x):
     return "New positive: {:,}".format(x)

except it doesn't even have a name!

Adding a QR Code

For more info, you can visit the CTP website, we insert a QR code which will show on the E-Ink display very nicely and can be scanned to get the full report

magtag.graphics.qrcode(b"https://covidtracking.com/data", qr_size=2, x=240, y=70)

The 'qr_size' indicates the scaling, e.g. how big the pixel squares are. X and Y coordinates puts it over on the bottom right

Connect and Update

The main chunk of code turns on the NeoPixels red for an indicator that we're connecting to the Internet, gets the local time (we need this later), updates a text box in the top-right with the timestamp of the current date/time so you know when it was last running, then calls magtag.fetch() to update all the text boxes.

magtag.peripherals.neopixels.brightness = 0.1
magtag.peripherals.neopixel_disable = False # turn on lights
magtag.peripherals.neopixels.fill(0x0F0000) # red!

magtag.get_local_time()
try:
    now = time.localtime()
    print("Now: ", now)

    # display the current time since its the last-update
    updated_at = "%d/%d\n%d:%02d" % now[1:5]
    magtag.set_text(updated_at, 6, False)

    # get data from the Covid Tracking Project
    value = magtag.fetch()
    print("Response is", value)

    # OK we're done!
    magtag.peripherals.neopixels.fill(0x000F00) # greten
except (ValueError, RuntimeError) as e:
    print("Some error occured, trying again later -", e)

time.sleep(2) # let screen finish updating

After the display has updated, its time to go to sleep. For this project we want to wake up at exactly 8pm, which might be later today or it might be tomorrow. Since we don't know what day it will be, we first assume that we will be waking up later today by creating a new time structure with the same year, month, day as today but the hour, min, sec is DAILY_UPDATE_HOUR, 0, 0:

event_time = time.struct_time((now[0], now[1], now[2], DAILY_UPDATE_HOUR, 0, 0, -1, -1, now[8]))

Then we convert the current time, and the next-wakeup time to seconds using time.mktime() and subtract the difference. That is, what is the number of seconds between these two time points

remaining = time.mktime(event_time) - time.mktime(now)

If the amount of time is negative, that mean's that the "wake up today" time already happened, so we add 24-hours-worth of seconds to the time difference, to get to the event time one day later (tomorrow!)

if remaining < 0: # ah its aready happened today...
    remaining += 24 * 60 * 60 # wrap around to the next day

We then display that time in hours and minutes, just for us to debug as humans

remaining_hrs = remaining // 3660
remaining_min = (remaining % 3600) // 60
print("Gonna zzz for %d hours, %d minutes" % (remaining_hrs, remaining_min))

And finally, we go into deep sleep mode until that time comes up

# Turn it all off and go to bed till the next update time
magtag.exit_and_deep_sleep(remaining)

If you'd like to give your MagTag a custom plastic cutout, you can cut out this AI file on a laser cutter or CNC cutter out of 1.5mm thick material

This guide was first published on Dec 11, 2020. It was last updated on Dec 11, 2020.