There are so many cool projects that use the MagTag, so why limit yourself to just one at a time?

This project allows you to load eight different projects on your MagTag at the same time. You can select which project to display using the four built-in buttons and then have it display that project until you decide to change it.

This project is heavily based on some code that Adafruit community member @DavidGlaude wrote and posted on Twitter.

Parts

This kit contains all the parts except for a cable:

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...
$44.95
In Stock

Or get the pieces 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...
$34.95
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
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
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...
$3.95
In Stock

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.

Installing the Project Code

Download a zip of the project by clicking 'Download: Project Zip' below.

After unzipping the file, copy its contents to the CIRCUITPY drive which appears when the MagTag is connected to your computer via a USB cable and turned on via a small on/off switch onboard.

The files for this project just barely fit on the MagTag. To make sure you have enough space, you'll have to clear the MagTag filesystem which requires you to enter the REPL over a serial console. To do that, read through the three pages linked below.

Now that you have done that, enter the following two lines and it will erase all the files on your MagTag.

import storage
storage.erase_filesystem()

At this point, I would recommend going through the other guides that this project makes use of, which are linked below. For most of the projects, you can copy all of their contents to the CIRCUITPY drive. However, for the MagTag Progress Displays guide, only the epilogue18.bdf font and year_progress_percent.py should be copied over.

All the .py files for the individual projects need to be put in a new directory on the CIRCUITPY drive named projects/ and renamed

Here is a list of all the libraries required, since it's a lot easier to just copy them all over at once:

  • adafruit_bitmap_font
  • adafruit_display_shapes
  • adafruit_display_text
  • adafruit_imageload
  • adafruit_io
  • adafruit_magtag
  • adafruit_portalbase
  • adafruit_fakerequests
  • adafruit_miniqr
  • adafruit_progressbar
  • adafruit_requests
  • adafruit_slideshow
  • neopixel
  • simpleio

As far as the secrets.py file goes, one with all the necessary fields has been included in the project zip that you can just fill out as you go through each guide.

After you've copied everything over, this is what the CIRCUITPY drive should look like (you can click on each image to expand it since the text might be small on some screens).

# Based on code written by @DavidGlaude on Twitter
# https://twitter.com/DavidGlaude/status/1340365817138044933
# https://gist.github.com/dglaude/4bf8d0a13c9c8ca8b05d6c0e9176bd20

import time
import alarm
import displayio
import board
import adafruit_imageload
from adafruit_display_shapes.rect import Rect
from adafruit_magtag.magtag import Graphics
from digitalio import DigitalInOut, Direction, Pull

projects = [
    "weather",
    "spacex",
    "covid",
    "showerthoughts",
    "tides",
    "year",
    "showtimes",
    "slideshow",
]

btnA = DigitalInOut(board.D15)
btnA.direction = Direction.INPUT
btnA.pull = Pull.UP

btnB = DigitalInOut(board.D14)
btnB.direction = Direction.INPUT
btnB.pull = Pull.UP

btnC = DigitalInOut(board.D12)
btnC.direction = Direction.INPUT
btnC.pull = Pull.UP

btnD = DigitalInOut(board.D11)
btnD.direction = Direction.INPUT
btnD.pull = Pull.UP

graphics = Graphics(auto_refresh=False)
display = graphics.display
group = displayio.Group()

selector = False
if not btnA.value or not btnB.value or not btnC.value or not btnD.value:
    selector = True

if selector:
    background = Rect(0, 0, 296, 128, fill=0xFFFFFF)
    group.append(background)
    for i in range(8):
        sprite_sheet, palette = adafruit_imageload.load(
            f"/bmps/{projects[i]}.bmp",
            bitmap=displayio.Bitmap,
            palette=displayio.Palette,
        )
        sprite = displayio.TileGrid(
            sprite_sheet,
            pixel_shader=palette,
            width=1,
            height=1,
            tile_width=62,
            tile_height=54,
            x=6 + 74 * (i % 4),
            y=6 + 62 * (i // 4),
        )
        group.append(sprite)

    rect = Rect(4, 4, 66, 58, outline=0x000000, stroke=2)
    group.append(rect)
    display.show(group)
    display.refresh()

    time.sleep(5)
    print("Ready")
    selected = 0
    while True:
        if not btnA.value and not btnD.value:
            alarm.sleep_memory[0] = selected
            break

        if not btnA.value and selected != 0 and selected != 4:
            selected -= 1
            rect.x -= 74
            display.refresh()
            print("left")
            time.sleep(5)
            continue

        if not btnB.value and selected > 3:
            selected -= 4
            rect.y -= 62
            display.refresh()
            print("up")
            time.sleep(5)
            continue

        if not btnC.value and selected < 4:
            selected += 4
            rect.y += 62
            display.refresh()
            print("down")
            time.sleep(5)
            continue

        if not btnD.value and selected != 3 and selected != 7:
            selected += 1
            rect.x += 74
            display.refresh()
            print("right")
            time.sleep(5)
            continue

btnA.deinit()
btnB.deinit()
btnC.deinit()
btnD.deinit()

print("Starting ", projects[int(alarm.sleep_memory[0])])
__import__("/projects/" + projects[int(alarm.sleep_memory[0])])
Be sure you have the libraries and secrets.py file complete and loaded onto the CIRCUITPY drive also or the code will not run properly.

Code Behavior

So, now that everything's all set up, it'd probably be a good idea to actually know how to use it. Basically, when the MagTag restarts or resets (from the slide switch, reset button, or through the serial terminal), you've got the option of going into a simple UI that will let you choose a project to load. You can enter this UI by pressing any of the four buttons when the MagTag is reloading and holding it down until the screen shows eight boxes with little pictures inside them. 

Once you're in the UI, use the four buttons to navigate it. Each button has an arrow on it, and pressing that button will move the cursor one square in that direction. Once the cursor (a black outline on the selected picture) is on the project you want, press and hold both the first and last buttons for five seconds. The MagTag can only update the screen once every five seconds, so keep that in mind while navigating the UI.

If you don't press a button when the code is restarting, it will automatically run the last run project. However, due to the constraints of the alarm library used to accomplish this, it only works during a soft reset (i.e. through the REPL or automatically) and not when the RESET button is pressed or the slide switch is turned off and on. If there isn't one, it will choose the first project and run that one.

First, the code imports the required libraries.

# Based on code written by @DavidGlaude on Twitter
# https://twitter.com/DavidGlaude/status/1340365817138044933
# https://gist.github.com/dglaude/4bf8d0a13c9c8ca8b05d6c0e9176bd20

import time
import alarm
import displayio
import board
import adafruit_imageload
from adafruit_display_shapes.rect import Rect
from adafruit_magtag.magtag import Graphics
from digitalio import DigitalInOut, Direction, Pull

Next, a list of the projects to choose from is declared. The names in this list should match the name of the .bmp used in the selection screen and the .py file in the projects/ directory, so weather has /bmps/weather.bmp and /projects/weather.py.

projects = [
    "weather",
    "spacex",
    "covid",
    "showerthoughts",
    "tides",
    "year",
    "showtimes",
    "slideshow",
]

Then, the four buttons that will be used to navigate the UI are initialized.

btnA = DigitalInOut(board.D15)
btnA.direction = Direction.INPUT
btnA.pull = Pull.UP

btnB = DigitalInOut(board.D14)
btnB.direction = Direction.INPUT
btnB.pull = Pull.UP

btnC = DigitalInOut(board.D12)
btnC.direction = Direction.INPUT
btnC.pull = Pull.UP

btnD = DigitalInOut(board.D11)
btnD.direction = Direction.INPUT
btnD.pull = Pull.UP

After that, the display is set up and the code checks to see if any buttons are pressed down. If any of them are, that means that the code will let the user choose a project to load. If none of them are, then the most recently loaded project will be loaded (if no project has been previously loaded, it defaults to the first one).

graphics = Graphics(auto_refresh=False)
display = graphics.display
group = displayio.Group()

selector = False
if not btnA.value or not btnB.value or not btnC.value or not btnD.value:
    selector = True

The code now checks to see if it should run the UI to let the user select the project to load. If it should, it then sets up the display with a white background and all the background images.

The MagTag is rather particular about what bmps it supports, so if you want to make your own bmps, click the link below. Just remember that for the MagTag, you need to use 8-bit indexed color.

The colors that I used are: 0x000000, 0xb1afad, 0x70696b, and 0xffffff

if selector:
    background = Rect(0, 0, 296, 128, fill=0xFFFFFF)
    group.append(background)
    for i in range(8):
        sprite_sheet, palette = adafruit_imageload.load(
            f"/bmps/{projects[i]}.bmp",
            bitmap=displayio.Bitmap,
            palette=displayio.Palette,
        )
        sprite = displayio.TileGrid(
            sprite_sheet,
            pixel_shader=palette,
            width=1,
            height=1,
            tile_width=62,
            tile_height=54,
            x=6 + 74 * (i % 4),
            y=6 + 62 * (i // 4),
        )
        group.append(sprite)

Before the main loop is started, there's still some more display setup to do. A hollow rectangle is added that will be used as a sort of cursor to show what project is currently selected, and then the whole display group is displayed. The code then waits a few seconds and sets selected, which is used to track the currently selected project, to 0.

[...]   
    rect = Rect(4, 4, 66, 58, outline=0x000000, stroke=2)
    group.append(rect)
    display.show(group)
    display.refresh()

    time.sleep(5)
    print("Ready")
    selected = 0

The code now enters the main loop. It first checks if the first and last buttons are selected. If they are, it makes the first item in alarm.sleep_memory the selected variable. If another button is selected, it moves the cursor rectangle in the direction indicated by the arrows on the MagTag buttons (first is left, second is up, third is down, fourth is right), refreshes the display, and changes the selected variable to reflect where the cursor is.

[...]   
    while True:
        if not btnA.value and not btnD.value:
            alarm.sleep_memory[0] = selected
            break
        
        if not btnA.value and selected != 0 and selected != 4:
            selected -= 1
            rect.x -= 74
            display.refresh()
            print("left")
            time.sleep(5)
            continue

        if not btnB.value and selected > 3:
            selected -= 4
            rect.y -= 62
            display.refresh()
            print("up")
            time.sleep(5)
            continue

        if not btnC.value and selected < 4:
            selected += 4
            rect.y += 62
            display.refresh()
            print("down")
            time.sleep(5)
            continue

        if not btnD.value and selected != 3 and selected != 7:
            selected += 1
            rect.x += 74
            display.refresh()
            print("right")
            time.sleep(5)
            continue

Now that the main loop is done, the buttons can be deinitialized so that they don't conflict with any buttons used in the chosen project.

btnA.deinit()
btnB.deinit()
btnC.deinit()
btnD.deinit()

Finally, the first item in alarm.sleep_memory is used as an index of the projects list to get the project to import. When something is imported like at the top of this file, it is usually a class, so it usually doesn't run anything but imports until it is initialized. In this case, a script is being imported so it is run just like if it was code.py or if it was run with python file.py on a computer.

print("Starting ", projects[int(alarm.sleep_memory[0])])
__import__("/projects/" + projects[int(alarm.sleep_memory[0])])

This guide was first published on Dec 30, 2020. It was last updated on Dec 30, 2020.