The Adafruit MagTag is perfect for reminders of upcoming events. This includes space launches. and in this project, launches by SpaceX. SpaceX is launching numerous interesting missions including manned to the ISS, cargo for the ISS, Starlink satellites, and more.

The MagTag fetches launch JSON data via WiFi and displays it on the beautiful eInk display. The mission, when the launch is occurring and a description of the mission (if available) and formatted onto the display.

Place the MagTag on a desk or on a refrigerator - never miss another launch again.

The current version initiates a deep sleep for 24 hours between refreshes, which should make a fully charged battery last a long time. You will still have to charge it up via a USB cable periodically - if it doesn't update, charge it.

This project requires CircuitPython 6.1.0 beta 2 or higher.

Parts

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...
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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
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...
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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...
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As technology changes and adapts, so does Adafruit. This  USB Type A to Type C cable will help you with the transition to USB C, even if you're still...
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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!

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.

wireless_Untitled.jpg
Image via GitHub SpaceX-API Project (project license Apache 2.0)

Projects that use Adafruit displays with WiFi often read local or remote data and display it on the screen. For this project, data from a 3rd party website that provides SpaceX data was used.

The SpaceX-API project is an Open Source REST API for rocket, core, capsule, pad, and launch data. They state "We are not affiliated, associated, authorized, endorsed by, or in any way officially connected with Space Exploration Technologies Inc (SpaceX), or any of its subsidiaries or its affiliates. The names SpaceX as well as related names, marks, emblems and images are registered trademarks of their respective owners."

The url https://api.spacexdata.com/v4/launches/next provides the data for the next launch in JSON format. The project is licensed under the Apache 2.0 License.

Details on what data is available can be found at https://github.com/r-spacex/SpaceX-API.

Three fields which were chosen to display in this project:

  1. name - the mission name
  2. data_local - the launch date locally when the launch will occur
  3. details - details about the launch (when available), a long text string

If other data is desired, the code only need to get the data in the desired fields.

This project requires CircuitPython 6.1.0 beta 2 or higher.

Libraries

The project needs no other libraries other than those in the MagTag CircuitPython Libraries page.

Fonts

To take advantage of the lovely eInk display, 4 different fonts are used. They are obtained when downloading all the project resources using "Download Project Zip" in the code window below. The font files below can be placed in the fonts/ directory on the CIRCUITPY drive which appears on your computer when the MagTag is plugged into your computer via a known good data USB-C cable.

  • Lato-Bold-ltd-25.bdf
  • Arial-Bold-12.bdf
  • Arial-12.bdf

Note the Lato-Bold-ltd-25.bdf font only has the letters to display "Next SpaceX Launch". This is to save space on the limited amount of flash on the MagTag. Lato is a freely licensed version of Arial provided by Google. An additional, built-in font in the terminalio library is used for the details.

If you want to look at using your own fonts, see the excellent guide Custom Fonts for CircuitPython Displays.

Code

Click the "Download Project Zip" link in the code window below and save the file to your computer in a place you can remember. Plug your MagTag into your computer via a known good USB-A to USB-C data cable. A new drive named CIRCUITPY should appear. Open up the Zip file and copy out the contents to your computer. Copy the code.py file from the directory you unzip the files to the MagTag in the main directory on the CIRCUITPY drive. Copy the four .bdf font files to the root directory also.

If you're having difficulty running this example, it could be because your MagTag CircuitPython firmware or library needs to be upgraded! Please be sure to follow https://learn.adafruit.com/adafruit-magtag/circuitpython to install the latest CircuitPython firmware and then also replace/update ALL the MagTag-specific libraries mentioned here https://learn.adafruit.com/adafruit-magtag/circuitpython-libraries-2
# SpaceX Launch Display, by Anne Barela November 2020
# MIT License - for Adafruit Industries LLC
# See https://github.com/r-spacex/SpaceX-API for API info

import time
import terminalio
from adafruit_magtag.magtag import MagTag

months = ["January", "February", "March", "April", "May", "June", "July",
          "August", "September", "October", "November", "December"]
USE_24HR_TIME = True
# in seconds, we can refresh about 100 times on a battery
TIME_BETWEEN_REFRESHES = 24 * 60 * 60  # once a day delay

# Set up data location and fields
DATA_SOURCE = "https://api.spacexdata.com/v4/launches/next"
DETAIL_LOCATION = ['details']
NAME_LOCATION = ['name']
DATE_LOCATION = ['date_local']

# These functions take the JSON data keys and does checks to determine
#   how to display the data. They're used in the add_text blocks below

def mission_transform(val):
    if val == None:
        val = "Unavailable"
    return "Mission: " + val

def time_transform(val2):
    if val2 == None:
        return "When: Unavailable"
    month = int(val2[5:7])
    day = int(val2[8:10])
    hour = int(val2[11:13])
    min = int(val2[14:16])

    if USE_24HR_TIME:
        timestring = "%d:%02d" % (hour, min)
    elif hour > 12:
        timestring = "%d:%02d pm" % (hour-12, min)
    else:
        timestring = "%d:%02d am" % (hour, min)

    return "%s %d, at %s" % (months[month-1], day, timestring)

def details_transform(val3):
    if val3 == None or not len(val3):
        return "Details: To Be Determined"
    return "Details: " + val3[0:166] + "..."

# Set up the MagTag with the JSON data parameters
magtag = MagTag(
    url=DATA_SOURCE,
    json_path=(NAME_LOCATION, DATE_LOCATION, DETAIL_LOCATION)
)

magtag.add_text(
    text_font="/fonts/Lato-Bold-ltd-25.bdf",
    text_position=(10, 15),
    is_data=False
)
# Display heading text below with formatting above
magtag.set_text("Next SpaceX Launch")

# Formatting for the mission text
magtag.add_text(
    text_font="/fonts/Arial-Bold-12.pcf",
    text_position=(10, 38),
    text_transform=mission_transform
)

# Formatting for the launch time text
magtag.add_text(
    text_font="/fonts/Arial-12.bdf",
    text_position=(10, 60),
    text_transform=time_transform
)

# Formatting for the details text
magtag.add_text(
    text_font=terminalio.FONT,
    text_position=(10, 94),
    line_spacing=0.8, 
    text_wrap=47,     # wrap text at this count
    text_transform=details_transform
)

try:
    # Have the MagTag connect to the internet
    magtag.network.connect()
    # This statement gets the JSON data and displays it automagically
    value = magtag.fetch()
    print("Response is", value)
except (ValueError, RuntimeError) as e:
    print("Some error occured, retrying! -", e)

# wait 2 seconds for display to complete
time.sleep(2)
magtag.exit_and_deep_sleep(TIME_BETWEEN_REFRESHES)

All Files

The directory listings at left show the main/root directory of the CIRCUITPY drive, the /lib directory, and the /fonts directory to illustrate which files are needed on the device.

Code Runthrough

The adafruit_magtag library handles much of the internet data fetching and data display for guides like this.

Three magtag.add_text transform functions are defined. They each specify how three different JSON text fields are displayed. time_transform has two different ways to display the time. One in month, day, year, time format and one in year, month, day, time format. Select the one you want and  comment out the other (or create your own, the data returned is formatted as follows: 

2020-12-05T11:39:00-05:00

Error checking is used if fields are blank to note that status on the display.

The MagTag is then invoked with the JSON data.

Each magtag.add_text block defines the data to display. There are four, the first one for the title (is_data = False to set so the function knows this is not a JSON text field). Each text display as a different font in this example (although you can use the same font for multiple fields). The text_position varies for each to spread text over the display. On the last field, there is a text_wrap property to automatically wrap long lines of text, perfect for the long description.

Finally a 2 second delay allows the screen to refresh. Then the board deep sleeps for the specified delay in seconds (set to 24 hours by default).

This example was kept fairly basic to illustrate how to do JSON data fetching and display the data on the MagTag.

A number of additions could be useful. Note, more elaborate display techniques might be beyond the capabilities of the adafruit_magtag library but could be implemented in more discrete code.

Low Power

It is likely one charge of the battery might last a month or so with this change and checking the data once a day. The deep sleep code is still beta, additional savings may be seen. If the display doesn't update after the launch, be sure to charge the battery for awhile.

Countdown to Launch

Use Adafruit IO to get the correct local time and make a display of the days, hours, and minutes until launch. See the following code examples for time manipulation (warning: more intermediate skills may be needed):

The NeoPixels could light up to let the user know a launch is imminent or a sound could be made. This will draw more power and shorten battery life. This isn't a worry if always on USB power.

Launchpad

The launchpad data was a text field in the previous version of the API. Often details contains the launchpad data too. Either have a function to convert the new launchpad number to a known value or parse it from the details. An example in details is "LC-39A, Kennedy Space Center".

Other Space APIs

I chose SpaceX as I live near Cape Canaveral and I like to watch the launches. There are other space launch data feeds that could be used with changes to the URL, fields used, and formatting. For example, see:

This guide was first published on Dec 02, 2020. It was last updated on Dec 02, 2020.