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What’s Fresh Today? In-Season Produce Reminder for Adafruit MagTag

What’s Fresh Today? In-Season Produce Reminder for Adafruit MagTag

Get to know your local fruits and veggies

Image for user pburgess
by Phillip Burgess
published December 07, 2020, last edited February 11, 2026
posted in CircuitPython Internet of Things - IOT LCDs & Displays/ eInk / ePaper
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Project guide

Overview

circuitpython_produce-banner.jpg

We live in a bright, if somewhat detached, future. In just about any city, 365 days a year, snow or desert heat, you can buy a pineapple. Not canned…an actual tropical pineapple fruit from across the globe, in your hand. It’s amazing when you think about it. Behind the scenes, it takes an army to get that pineapple (or any other peculiar food) to you alive…inordinate energy and labor, and all that entails. So tasty, but it does give one pause.

Consider the benefits of locally-grown fruits and vegetables sold at farmers’ markets, produce stands and smaller independent grocers:

  • Vine-ripened foods taste amazing, so much more flavorful than canned, frozen or store-shelf ripened. If you’ve ever wondered “why are tomatoes considered a fruit?”, now you’ll know. Sweetness and flavor!
  • Local growers often have nifty varieties too delicate for industrial-scale agriculture and distribution. Flavors, colors, sizes and shapes you seldom see at big grocers. Romanesco broccoli looks exactly like 1990s computer graphics.
  • Fewer middlemen means farm workers have a better chance for a living wage.
  • A lower carbon footprint as your food arrives from a nearby county rather than four states away, and with less processing, packaging and waste.

Not to push an agenda — let’s be practical, pineapple is delicious, among other fruits and veggies you might otherwise miss year ’round. The notion is to prioritize local seasonal selections, for some good reasons above, then round out anything else during routine grocery trips.

Okay then, how to start? It’s not just about what can grow locally, but when? Without freezers or cans, just fresh off the land, your options change throughout the year. Meal planning suddenly isn’t so simple. This knowledge goes back generations…we’ve started with data from the venerable Farmers’ Almanac and fully automated it. Punch in your location and MagTag keeps track of the seasons and offers suggestions. High tech, but pragmatic.

This currently only works for the lower 48 United States. Information for Alaska, Hawaii (Pineapple!), and non-US countries is not present in the dataset.

Parts Required

The MagTag starter kit includes an e-ink development board, LiPoly battery and magnetic feet…bring-your-own USB type A to type C cable. Or the individual pieces can be rounded up separately…

MagTag dev board with enclosure pieces, four magnet feet, and lipoly battery
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...
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Angled shot of rectangle-shaped electronic ink display breakout with the text: "MAGTAG 2025 Edition with SSD1680 Chipset"
The Adafruit MagTag combines the 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 is...
guides with product
$34.95
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Angled shot of a coiled black, USB-C to USB-A cable.
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...
$4.95
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Lithium Ion Polymer Battery 3.7v 420mAh with JST 2-PH connector and short cable
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
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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)!

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Install CircuitPython

Make sure that you update the TinyUF2 Bootloader before installing CircuitPython!

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.

WARNING: The updated Adafruit MagTag 2025 Edition will not work with CircuitPython 9.2.x or earlier. Make sure you install 10.x.x or later!

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

You can use a 9.x.x release for a pre-2025 MagTag. You must use a 10.x.x release for the updated MagTag 2025 Edition.

(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).

adafruit_products_MagTag_top.jpg

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!

Make sure that you update the TinyUF2 Bootloader before following these steps for the UF2 bootloader!
adafruit_products_IMG_0169.jpg

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.

adafruit_products_MagTag_pinouts_Reset_and_Boot0.jpg

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.

adafruit_products_image.png

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

adafruit_products_image.png

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)

adafruit_products_image.png

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!

adafruit_products_Metro_ESP32_S2_binary_install.png

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.

adafruit_products_Metro_ESP32_S2_CIRCUITPY.png

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.

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CircuitPython Internet Test

One of the great things about most Espressif microcontrollers are their built-in WiFi capabilities. This page covers the basics of getting connected using CircuitPython.

The first thing you need to do is update your code.py to the following (it will error until WiFi details are added). Click the Download Project Bundle button to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Download Project Bundle
Copy Code 
# SPDX-FileCopyrightText: 2020 Brent Rubell for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import os
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"

print("ESP32-S2 WebClient Test")

print(f"My MAC address: {[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(f"Connecting to {os.getenv('CIRCUITPY_WIFI_SSID')}")
wifi.radio.connect(os.getenv("CIRCUITPY_WIFI_SSID"), os.getenv("CIRCUITPY_WIFI_PASSWORD"))
print(f"Connected to {os.getenv('CIRCUITPY_WIFI_SSID')}")
print(f"My IP address: {wifi.radio.ipv4_address}")

ping_ip = ipaddress.IPv4Address("8.8.8.8")
ping = wifi.radio.ping(ip=ping_ip)

# retry once if timed out
if ping is None:
    ping = wifi.radio.ping(ip=ping_ip)

if ping is None:
    print("Couldn't ping 'google.com' successfully")
else:
    # convert s to ms
    print(f"Pinging 'google.com' took: {ping * 1000} ms")

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

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

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

print()

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

print("Done")
View on GitHub

Your CIRCUITPY drive should resemble the following.

CIRCUITPY

To get connected, the next thing you need to do is update the settings.toml file.

The settings.toml 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 settings.toml file, that is on your CIRCUITPY drive, to hold secret/private/custom data. That way you can share your main project without worrying about accidentally sharing private stuff.

If you have a fresh install of CircuitPython on your board, the initial settings.toml file on your CIRCUITPY drive is empty.

To get started, you can update the settings.toml on your CIRCUITPY drive to contain the following code.

Download File
Copy Code 
# SPDX-FileCopyrightText: 2023 Adafruit Industries
#
# SPDX-License-Identifier: MIT

# This is where you store the credentials necessary for your code.
# The associated demo only requires WiFi, but you can include any
# credentials here, such as Adafruit IO username and key, etc.
CIRCUITPY_WIFI_SSID = "your-wifi-ssid"
CIRCUITPY_WIFI_PASSWORD = "your-wifi-password"
View on GitHub

This file should contain a series of Python variables, each assigned to a string. Each variable should describe what it represents (say wifi_ssid), followed by an = (equals sign), followed by the data in the form of a Python string (such as "my-wifi-password" including the quote marks).

At a minimum you'll need to add/update your WiFi SSID and WiFi password, 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.

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 settings.toml - keep that out of GitHub, Discord or other project-sharing sites.

Don't share your settings.toml file! It has your passwords and API keys in it!

If you connect to the serial console, you should see something like the following:

adafruit_products_1__screen__Users_brentrubell__screen_.png

In order, the example code...

Checks the ESP32's MAC address.

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print(f"My MAC address: {[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.

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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()

Connects to the access point you defined in the settings.toml file, and prints out its local IP address.

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print(f"Connecting to {os.getenv('WIFI_SSID')}")
wifi.radio.connect(os.getenv("WIFI_SSID"), os.getenv("WIFI_PASSWORD"))
print(f"Connected to {os.getenv('WIFI_SSID')}")
print(f"My IP address: {wifi.radio.ipv4_address}")

Attempts to ping a Google DNS server to test connectivity. If a ping fails, it returns None. Initial pings can sometimes fail for various reasons. So, if the initial ping is successful (is not None), it will print the echo speed in ms. If the initial ping fails, it will try one more time to ping, and then print the returned value. If the second ping fails, it will result in "Ping google.com: None ms" being printed to the serial console. Failure to ping does not always indicate a lack of connectivity, so the code will continue to run.

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ping_ip = ipaddress.IPv4Address("8.8.8.8")
ping = wifi.radio.ping(ip=ping_ip) * 1000
if ping is not None:
    print(f"Ping google.com: {ping} ms")
else:
    ping = wifi.radio.ping(ip=ping_ip)
    print(f"Ping google.com: {ping} ms")

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.

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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. 

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Copy Code 
print(f"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. 

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Copy Code 
print(f"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.

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

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

IPv6 Networking

Starting in CircuitPython 9.2, IPv6 networking is available on most Espressif wifi boards. Socket-using libraries like adafruit_requests and adafruit_ntp will need to be updated to use the new APIs and for now can only connect to services on IPv4.

IPv6 connectivity & privacy

IPv6 addresses are divided into many special kinds, and many of those kinds (like those starting with FC, FD, FE) are private or local; Addresses starting with other prefixes like 2002: and 2001: are globally routable. In 2024, far from all ISPs and home networks support IPv6 internet connectivity. For more info consult resources like Wikipedia. If you're interested in global IPv6 connectivity you can use services like Hurricane Electric to create an "IPv6 tunnel" (free as of 2024, but requires expertise and a compatible router or host computer to set up)

It's also important to be aware that, as currently implemented by Espressif, there are privacy concerns especially when these devices operate on the global IPv6 network: The device's unique identifier (its EUI-64 or MAC address) is used by default as part of its IPv6 address. This means that the device identity can be tracked across multiple networks by any service it connects to.

Enable IPv6 networking

Due to the privacy consideration, IPv6 networking is not automatically enabled. Instead, it must be explicitly enabled by a call to start_dhcp_client with the ipv6=True argument specified:

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wifi.start_dhcp_client(ipv6=True)

Check IP addresses

The read-only addresses property of the wifi.radio object holds all addresses, including IPv4 and IPv6 addresses:

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>>> wifi.radio.addresses
('FE80::7EDF:A1FF:FE00:518C', 'FD5F:3F5C:FE50:0:7EDF:A1FF:FE00:518C', '10.0.3.96')

The wifi.radio.dns servers can be IPv4 or IPv6:

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>>> wifi.radio.dns
('FD5F:3F5C:FE50::1',)
>>> wifi.radio.dns = ("1.1.1.1",)
>>> wifi.radio.dns
('1.1.1.1',)

Ping v6 networks

wifi.radio.ping accepts v6 addresses and names:

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Copy Code 
>>> wifi.radio.ping("google.com")
0.043
>>> wifi.radio.ping("ipv6.google.com")
0.048

Create & use IPv6 sockets

Use the address family socket.AF_INET6. After the socket is created, use methods like connect, send, recfrom_into, etc just like for IPv4 sockets. This code snippet shows communicating with a private-network NTP server; this IPv6 address will not work on your network:

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>>> ntp_addr = ("fd5f:3f5c:fe50::20e", 123)
>>> PACKET_SIZE = 48
>>> 
>>> buf = bytearray(PACKET_SIZE)
>>> with socket.socket(socket.AF_INET6, socket.SOCK_DGRAM) as s:
...     s.settimeout(1)
...     buf[0] = 0b0010_0011
...     s.sendto(buf, ntp_addr)
...     print(s.recvfrom_into(buf))
...     print(buf)
... 
48
(48, ('fd5f:3f5c:fe50::20e', 123))
bytearray(b'$\x01\x03\xeb\x00\x00\x00\x00\x00\x00\x00GGPS\x00\xeaA0h\x07s;\xc0\x00\x00\x00\x00\x00\x00\x00\x00\xeaA0n\xeb4\x82-\xeaA0n\xebAU\xb1')

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Getting The Date & Time

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

adafruit_products_image.png
"My Key" has been replaced with a key-shaped icon!

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

adafruit_products_image.png

Go to the settings.toml file on your CIRCUITPY drive (or create one with the text editor with your operating system) and add three lines for AIO_USERNAME, ADAFRUIT_AIO_KEY and TIMEZONE so you get something like the following:

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Copy Code 
# 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

CIRCUITPY_WIFI_SSID = "your-wifi-ssid"
CIRCUITPY_WIFI_PASSWORD = "your-wifi-password"
ADAFRUIT_AIO_USERNAME = "your-adafruit-io-username"
ADAFRUIT_AIO_KEY = "your-adafruit-io-key"
# Timezone names from http://worldtimeapi.org/timezones
TIMEZONE="America/New_York"

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 Worldtime 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

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Copy Code 
import ipaddress
import os
import ssl
import wifi
import socketpool
import adafruit_requests


# Get our username, key and desired timezone
ssid = os.getenv("CIRCUITPY_WIFI_SSID")
password = os.getenv("CIRCUITPY_WIFI_PASSWORD")
aio_username = os.getenv("ADAFRUIT_AIO_USERNAME")
aio_key = os.getenv("ADAFRUIT_AIO_KEY")
timezone = os.getenv("TIMEZONE")
TIME_URL = f"https://io.adafruit.com/api/v2/{aio_username}/integrations/time/strftime?x-aio-key={aio_key}&tz={timezone}"
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", ssid)
wifi.radio.connect(ssid, password)
print(f"Connected to {ssid}!")
print("My IP address is", wifi.radio.ipv4_address)

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

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!

adafruit_products_image.png

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

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MagTag-Specific CircuitPython Libraries

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
  • adafruit_minimqtt - This library provides MQTT service for Adafruit IO.

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.

settings.toml

Even if you aren't planning to go online with your MagTag, you'll need to have a settings.toml 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. See the previous page on creating a settings.toml file.

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Install Code and Graphics

Back up any existing code or files you want to keep from your MagTag CIRCUITPY drive.

Fetch the files for our Seasonal Produce project from Github by clicking "Download Project Zip" at the top of the code below - this will fetch all the necessary files in one zip file which you can then use in the project.

Here’s a map of all this project’s required images, fonts and code on the CIRCUITPY drive:

CIRCUITPY
Download Project Bundle
Copy Code 
# SPDX-FileCopyrightText: 2020 Phillip Burgess for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""
Seasonal produce finder for Adafruit MagTag w/CircuitPython 6.1 or later.
Lists in-season fruits and vegetables for a user's location and season.
"Smart cursive" BDF font by Thomas A. Fine, helvB12 from Xorg fonts.
"""

# pylint: disable=import-error, line-too-long

from os import getenv
import time
import rtc
from adafruit_display_shapes.rect import Rect
from adafruit_magtag.magtag import MagTag
from produce import Produce


# 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."
    )

# CONFIGURABLE SETTINGS and ONE-TIME INITIALIZATION ------------------------

TWELVE_HOUR = True # If set, show 12-hour vs 24-hour (e.g. 3:00 vs 15:00)
DD_MM = False      # If set, show DD/MM instead of MM/DD dates
# Location of produce data (file:// or http:// or https://):
JSON_URL = 'https://raw.githubusercontent.com/adafruit/Adafruit_Learning_System_Guides/master/MagTag/MagTag_Seasonal_Produce/produce.json'

# Location is configured in settings.toml. If location is not contained there,
# default value below will be used.
LOCATION = getenv('location', 'NY') # default to 'NY'

PRODUCE = Produce(JSON_URL, LOCATION)
MAGTAG = MagTag(rotation=0) # Portrait (vertical) display


# SOME UTILITY FUNCTIONS ---------------------------------------------------

def hh_mm(time_struct, twelve_hour=True):
    """ Given a time.struct_time, return a string as H:MM or HH:MM, either
        12- or 24-hour style depending on twelve_hour flag.
    """
    if twelve_hour:
        if time_struct.tm_hour > 12:
            hour_string = str(time_struct.tm_hour - 12) # 13-23 -> 1-11 (pm)
        elif time_struct.tm_hour > 0:
            hour_string = str(time_struct.tm_hour) # 1-12
        else:
            hour_string = '12' # 0 -> 12 (am)
    else:
        hour_string = '{hh:02d}'.format(hh=time_struct.tm_hour)
    return hour_string + ':{mm:02d}'.format(mm=time_struct.tm_min)


# GRAPHICS INITIALIZATION --------------------------------------------------

MAGTAG.graphics.set_background('bitmaps/produce.bmp')

# Produce list is inserted at this position
MAGTAG.add_text(
    text_font='/fonts/cursive-smart.pcf',
    text_position=(3, 2),
    line_spacing=1.0,
    text_anchor_point=(0, 0),  # top left
    is_data=False, # we'll set this text manually
)

# Add 14-pixel-tall black bar at bottom of display. It's a distinct layer
# (not just background) to appear on top of produce list if it runs long.
MAGTAG.graphics.root_group.append(Rect(0, MAGTAG.graphics.display.height - 14,
                                   MAGTAG.graphics.display.width,
                                   MAGTAG.graphics.display.height, fill=0x0))

# Center white text label over black bar to show last update time
# (Initially a placeholder, string is not assigned to label until later)
MAGTAG.add_text(
    text_font='/fonts/helvB12.pcf',
    text_position=(MAGTAG.graphics.display.width // 2,
                   MAGTAG.graphics.display.height - 1),
    text_color=0xFFFFFF,
    text_anchor_point=(0.5, 1),
    is_data=False, # we'll set this text manually later
)


# MAIN LOOP ----------------------------------------------------------------

# FYI: Not really a "loop" -- deep sleep makes the whole system restart on
# wake, this only needs to run once.

try:
    MAGTAG.network.connect() # Sneak this in last, as WiFi uses power
    print('Updating time')
    MAGTAG.get_local_time()
    NOW = rtc.RTC().datetime
    print(NOW)

    print('Updating produce')
    PRODUCE.fetch(MAGTAG)

    # Set the "Updated" date and time label
    if DD_MM:
        DATE = '%d/%d' % (NOW.tm_mday, NOW.tm_mon)
    else:
        DATE = '%d/%d' % (NOW.tm_mon, NOW.tm_mday)
    MAGTAG.set_text('Updated %s %s' % (DATE, hh_mm(NOW, TWELVE_HOUR)), 1,
                    auto_refresh=False)

    # Look up the matching produce data (returned as list of strings)
    PRODUCE_LIST = PRODUCE.in_season(NOW.tm_mon)
    NUM_ITEMS = len(PRODUCE_LIST)
    print('Produce list: ', PRODUCE_LIST)
    # List one item per line since some may be long
    VEGGIE_LIST = ''
    for item in PRODUCE_LIST:
        VEGGIE_LIST += '\n'.join(MAGTAG.wrap_nicely(item, 15)) + '\n'
    MAGTAG.set_text(VEGGIE_LIST) # Update list on the display

    time.sleep(2) # Allow refresh to finish before deep sleep
    print('Zzzz time')
    MAGTAG.exit_and_deep_sleep(24 * 60 * 60) # 24 hour snooze

except RuntimeError as error:
    # If there's an error above, no harm, just try again in ~15 minutes.
    # Usually it's a common network issue or time server hiccup.
    print('Retrying in 15 min - ', error)
    MAGTAG.exit_and_deep_sleep(15 * 60) # 15 minute snooze
View on GitHub

Unzip this file after downloading.

The bitmaps and fonts folders should be copied into the CIRCUITPY root directory. If folders with these names already exist, copy the individual .BMP and .BDF files into the corresponding folders.

code.py and produce.py should also be copied to the CIRCUITPY root directory.

One of the files in the project folder — produce.json — does not get copied. Our code will pull the latest from the internet each time it’s needed, so it always has the latest information.

One additional file — settings.toml — isn’t distributed in the project folder…if you don’t already have this file from a prior MagTag project, we’ll create this file on the next page.

If you run out of space when copying items to CIRCUITPY: make a backup of any files currently on that drive, then delete files that aren’t related to this project to free up space.

The following page gets mirrored into several MagTag guides…being a catch-all for many things, it kind of goes off into the weeds. Only the first part is important — getting the settings.toml file created if you haven’t before, setting up WiFi network credentials and timezone in there — then you can skip ahead.

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CircuitPython Internet Test

One of the great things about most Espressif microcontrollers are their built-in WiFi capabilities. This page covers the basics of getting connected using CircuitPython.

The first thing you need to do is update your code.py to the following (it will error until WiFi details are added). Click the Download Project Bundle button to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Download Project Bundle
Copy Code 
# SPDX-FileCopyrightText: 2020 Brent Rubell for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import os
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"

print("ESP32-S2 WebClient Test")

print(f"My MAC address: {[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(f"Connecting to {os.getenv('CIRCUITPY_WIFI_SSID')}")
wifi.radio.connect(os.getenv("CIRCUITPY_WIFI_SSID"), os.getenv("CIRCUITPY_WIFI_PASSWORD"))
print(f"Connected to {os.getenv('CIRCUITPY_WIFI_SSID')}")
print(f"My IP address: {wifi.radio.ipv4_address}")

ping_ip = ipaddress.IPv4Address("8.8.8.8")
ping = wifi.radio.ping(ip=ping_ip)

# retry once if timed out
if ping is None:
    ping = wifi.radio.ping(ip=ping_ip)

if ping is None:
    print("Couldn't ping 'google.com' successfully")
else:
    # convert s to ms
    print(f"Pinging 'google.com' took: {ping * 1000} ms")

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

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

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

print()

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

print("Done")
View on GitHub

Your CIRCUITPY drive should resemble the following.

CIRCUITPY

To get connected, the next thing you need to do is update the settings.toml file.

The settings.toml 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 settings.toml file, that is on your CIRCUITPY drive, to hold secret/private/custom data. That way you can share your main project without worrying about accidentally sharing private stuff.

If you have a fresh install of CircuitPython on your board, the initial settings.toml file on your CIRCUITPY drive is empty.

To get started, you can update the settings.toml on your CIRCUITPY drive to contain the following code.

Download File
Copy Code 
# SPDX-FileCopyrightText: 2023 Adafruit Industries
#
# SPDX-License-Identifier: MIT

# This is where you store the credentials necessary for your code.
# The associated demo only requires WiFi, but you can include any
# credentials here, such as Adafruit IO username and key, etc.
CIRCUITPY_WIFI_SSID = "your-wifi-ssid"
CIRCUITPY_WIFI_PASSWORD = "your-wifi-password"
View on GitHub

This file should contain a series of Python variables, each assigned to a string. Each variable should describe what it represents (say wifi_ssid), followed by an = (equals sign), followed by the data in the form of a Python string (such as "my-wifi-password" including the quote marks).

At a minimum you'll need to add/update your WiFi SSID and WiFi password, 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.

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 settings.toml - keep that out of GitHub, Discord or other project-sharing sites.

Don't share your settings.toml file! It has your passwords and API keys in it!

If you connect to the serial console, you should see something like the following:

adafruit_products_1__screen__Users_brentrubell__screen_.png

In order, the example code...

Checks the ESP32's MAC address.

Download File
Copy Code 
print(f"My MAC address: {[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.

Download File
Copy Code 
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()

Connects to the access point you defined in the settings.toml file, and prints out its local IP address.

Download File
Copy Code 
print(f"Connecting to {os.getenv('WIFI_SSID')}")
wifi.radio.connect(os.getenv("WIFI_SSID"), os.getenv("WIFI_PASSWORD"))
print(f"Connected to {os.getenv('WIFI_SSID')}")
print(f"My IP address: {wifi.radio.ipv4_address}")

Attempts to ping a Google DNS server to test connectivity. If a ping fails, it returns None. Initial pings can sometimes fail for various reasons. So, if the initial ping is successful (is not None), it will print the echo speed in ms. If the initial ping fails, it will try one more time to ping, and then print the returned value. If the second ping fails, it will result in "Ping google.com: None ms" being printed to the serial console. Failure to ping does not always indicate a lack of connectivity, so the code will continue to run.

Download File
Copy Code 
ping_ip = ipaddress.IPv4Address("8.8.8.8")
ping = wifi.radio.ping(ip=ping_ip) * 1000
if ping is not None:
    print(f"Ping google.com: {ping} ms")
else:
    ping = wifi.radio.ping(ip=ping_ip)
    print(f"Ping google.com: {ping} ms")

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.

Download File
Copy Code 
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. 

Download File
Copy Code 
print(f"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. 

Download File
Copy Code 
print(f"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.

Download File
Copy Code 
print(f"Fetching and parsing json from {JSON_STARS_URL}")
response = requests.get(JSON_STARS_URL)
print("-" * 40)
print(f"CircuitPython GitHub Stars: {response.json()['stargazers_count']}")
print("-" * 40)

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

IPv6 Networking

Starting in CircuitPython 9.2, IPv6 networking is available on most Espressif wifi boards. Socket-using libraries like adafruit_requests and adafruit_ntp will need to be updated to use the new APIs and for now can only connect to services on IPv4.

IPv6 connectivity & privacy

IPv6 addresses are divided into many special kinds, and many of those kinds (like those starting with FC, FD, FE) are private or local; Addresses starting with other prefixes like 2002: and 2001: are globally routable. In 2024, far from all ISPs and home networks support IPv6 internet connectivity. For more info consult resources like Wikipedia. If you're interested in global IPv6 connectivity you can use services like Hurricane Electric to create an "IPv6 tunnel" (free as of 2024, but requires expertise and a compatible router or host computer to set up)

It's also important to be aware that, as currently implemented by Espressif, there are privacy concerns especially when these devices operate on the global IPv6 network: The device's unique identifier (its EUI-64 or MAC address) is used by default as part of its IPv6 address. This means that the device identity can be tracked across multiple networks by any service it connects to.

Enable IPv6 networking

Due to the privacy consideration, IPv6 networking is not automatically enabled. Instead, it must be explicitly enabled by a call to start_dhcp_client with the ipv6=True argument specified:

Download File
Copy Code 
wifi.start_dhcp_client(ipv6=True)

Check IP addresses

The read-only addresses property of the wifi.radio object holds all addresses, including IPv4 and IPv6 addresses:

Download File
Copy Code 
>>> wifi.radio.addresses
('FE80::7EDF:A1FF:FE00:518C', 'FD5F:3F5C:FE50:0:7EDF:A1FF:FE00:518C', '10.0.3.96')

The wifi.radio.dns servers can be IPv4 or IPv6:

Download File
Copy Code 
>>> wifi.radio.dns
('FD5F:3F5C:FE50::1',)
>>> wifi.radio.dns = ("1.1.1.1",)
>>> wifi.radio.dns
('1.1.1.1',)

Ping v6 networks

wifi.radio.ping accepts v6 addresses and names:

Download File
Copy Code 
>>> wifi.radio.ping("google.com")
0.043
>>> wifi.radio.ping("ipv6.google.com")
0.048

Create & use IPv6 sockets

Use the address family socket.AF_INET6. After the socket is created, use methods like connect, send, recfrom_into, etc just like for IPv4 sockets. This code snippet shows communicating with a private-network NTP server; this IPv6 address will not work on your network:

Download File
Copy Code 
>>> ntp_addr = ("fd5f:3f5c:fe50::20e", 123)
>>> PACKET_SIZE = 48
>>> 
>>> buf = bytearray(PACKET_SIZE)
>>> with socket.socket(socket.AF_INET6, socket.SOCK_DGRAM) as s:
...     s.settimeout(1)
...     buf[0] = 0b0010_0011
...     s.sendto(buf, ntp_addr)
...     print(s.recvfrom_into(buf))
...     print(buf)
... 
48
(48, ('fd5f:3f5c:fe50::20e', 123))
bytearray(b'$\x01\x03\xeb\x00\x00\x00\x00\x00\x00\x00GGPS\x00\xeaA0h\x07s;\xc0\x00\x00\x00\x00\x00\x00\x00\x00\xeaA0n\xeb4\x82-\xeaA0n\xebAU\xb1')

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Configure Location

A few more items need to go in the settings.toml file described on the prior page.

In addition to WiFi network credentials and timezone, our veggie code also needs:

  • ADAFRUIT_AIO_USERNAME and ADAFRUIT_AIO_KEY matching your Adafruit IO credentials. If logged into your account at adafruit.com, click the “IO” link in the top navigation bar, then “My Key.”

  • location is the 2-letter postal code for your state, in quotes: e.g. 'NY' or 'TX'.

This currently only works for the lower 48 United States. Information for Alaska, Hawaii, and non-US countries is not present in the dataset.
Download File
Copy Code 
CIRCUITPY_WIFI_SSID="your-wifi-ssid"
CIRCUITPY_WIFI_PASSWORD="your-wifi-password"
ADAFRUIT_AIO_USERNAME="my_username"
ADAFRUIT_AIO_KEY="my_key"
timezone="America/New_York"  # http://worldtimeapi.org/timezones
location="NY"

After editing and saving settings.toml, tap the reset button and within a minute or so you’ll see some veggies!

If the project does NOT start up: most likely the WiFi credentials are incorrect, or something is wrong with the settings.toml file syntax…make sure every quote, comma and colon is there and in the right place.

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Usage

circuitpython_produce-hand.jpg

Once configured for your location, there’s literally nothing to do. The device will quietly go about its business, checking for changes in the seasons and updating the list once a day. There are no buttons to press or menus to navigate.

When it’s time to go shopping, you can bring the MagTag list with you, or snap a picture with your smartphone before heading out.

Other Configurable Settings

Aside from the location (in settings.toml), there are some other configurable settings that can be adjusted in the code itself.

In code.py, starting around line 18 are a few global variables. Each of these is briefly commented in the code, but for posterity…

TWELVE_HOUR selects whether to display the “Updated” time as 12-hour vs. 24-hour time (e.g. 3:00 vs. 15:00). Default is True, use 12-hour format.

DD_MM selects whether the “Updated” date is displayed as day/month vs. month/day. Default is False — use month/day formatting — since the data is U.S.-centric for now, and that’s the more common date format here.

JSON_URL is the internet location of the agricultural data file. The default is a long URL pointing to a file hosted on Github that might see updates from time to time. It’s possible to use a file:// URL instead, and place this data on the CIRCUITPY drive…but that won’t automatically pick up any future changes to the data.

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