Code PyPortal with CircuitPython

Event Countdown

With the PyPortal coded in CircuitPython, we can set the date and time of a one-time occurrence, such as a conference, convention, or movie release date.

The PyPortal Countdown Clock will do the following:

  • Display a custom background .bmp for the event
  • Determine the current local time using the WiFi connection to the Internet
  • Draw out the countdown time in days, hours, and minutes
  • Display a second custom background graphic once the day of the event arrives

Adafruit IO Time Server

In order to get the precise time, our project will query the Adafruit IO Internet of Things service for the time. Adafruit IO is absolutely free to use, but you'll need to log in with your Adafruit account to use it. If you don't already have an Adafruit login, create one here.

If you haven't used Adafruit IO before, check out this guide for more info.

Once you have logged into your account, there are two pieces of information you'll need to place in your secrets.py file: Adafruit IO username, and Adafruit IO key. Head to io.adafruit.com and simply click the View AIO Key link on the left hand side of the Adafruit IO page to get this information.

Then, add them to the secrets.py file like this:

Download: file
secrets = {
    'ssid' : 'your_wifi_ssid',
    'password : 'your_wifi_password',
    'aio_username' : 'your_aio_username',
    'aio_key' : 'your_big_huge_super_long_aio_key'
    }

Install CircuitPython Code and Assets

In the embedded code element below, click on the Download: Project Zip link, and save the .zip archive file to your computer.

Then, uncompress the .zip file, it will unpack to a folder named PyPortal_EventCountdown.

Copy the contents of the PyPortal_EventCountdown directory to your PyPortal's CIRCUITPY drive, and then be sure to rename the eventcountdown.py file to code.py so it will automatically run when the PyPortal re-starts.

This is what the final contents of the CIRCUITPY drive will look like:

"""
This example will figure out the current local time using the internet, and
then draw out a countdown clock until an event occurs!
Once the event is happening, a new graphic is shown
"""
import time
import board
from adafruit_pyportal import PyPortal
from adafruit_bitmap_font import bitmap_font
from adafruit_display_text.label import Label

# The time of the thing!
EVENT_YEAR = 2019
EVENT_MONTH = 4
EVENT_DAY = 15
EVENT_HOUR = 9
EVENT_MINUTE = 0
# we'll make a python-friendly structure
event_time = time.struct_time((EVENT_YEAR, EVENT_MONTH, EVENT_DAY,
                               EVENT_HOUR, EVENT_MINUTE, 0,  # we don't track seconds
                               -1, -1, False))  # we dont know day of week/year or DST

# determine the current working directory
# needed so we know where to find files
cwd = ("/"+__file__).rsplit('/', 1)[0]
# Initialize the pyportal object and let us know what data to fetch and where
# to display it
pyportal = PyPortal(status_neopixel=board.NEOPIXEL,
                    default_bg=cwd+"/countdown_background.bmp")

big_font = bitmap_font.load_font(cwd+"/fonts/Helvetica-Bold-36.bdf")
big_font.load_glyphs(b'0123456789') # pre-load glyphs for fast printing
event_background = cwd+"/countdown_event.bmp"

days_position = (8, 207)
hours_position = (110, 207)
minutes_position = (220, 207)
text_color = 0xFFFFFF

text_areas = []
for pos in (days_position, hours_position, minutes_position):
    textarea = Label(big_font, max_glyphs=3)
    textarea.x = pos[0]
    textarea.y = pos[1]
    textarea.color = text_color
    pyportal.splash.append(textarea)
    text_areas.append(textarea)
refresh_time = None

while True:
    # only query the online time once per hour (and on first run)
    if (not refresh_time) or (time.monotonic() - refresh_time) > 3600:
        try:
            print("Getting time from internet!")
            pyportal.get_local_time()
            refresh_time = time.monotonic()
        except RuntimeError as e:
            print("Some error occured, retrying! -", e)
            continue

    now = time.localtime()
    print("Current time:", now)
    remaining = time.mktime(event_time) - time.mktime(now)
    print("Time remaining (s):", remaining)
    if remaining < 0:
        # oh, its event time!
        pyportal.set_background(event_background)
        while True:  # that's all folks
            pass
    secs_remaining = remaining % 60
    remaining //= 60
    mins_remaining = remaining % 60
    remaining //= 60
    hours_remaining = remaining % 24
    remaining //= 24
    days_remaining = remaining
    print("%d days, %d hours, %d minutes and %s seconds" %
          (days_remaining, hours_remaining, mins_remaining, secs_remaining))
    text_areas[0].text = '{:>2}'.format(days_remaining)  # set days textarea
    text_areas[1].text = '{:>2}'.format(hours_remaining) # set hours textarea
    text_areas[2].text = '{:>2}'.format(mins_remaining)  # set minutes textarea

    # update every 10 seconds
    time.sleep(10)
If you run into any errors, such as "ImportError: no module named `adafruit_display_text.label`" be sure to update your libraries to the latest release bundle!

How it Works

The PyPortal Countdown is doing a couple of cool things to make your event display:

Background

First, it displays a bitmap graphic named countdown_background.bmp as the screen's background. This is a 320 x 240 pixel RGB 16-bit raster graphic in .bmp format.

Time

In order to calculate the countdown, the PyPortal's CircuitPython code determines the local time by checking the internet time via the WiFi connection. It uses your IP address information to determine the local time. The good news is that once you've set up your timezone (or if the IP is fine) you do not have to adjust for daylight savings, leap years, etc.

In some cases, the time may not appear correctly based on your IP address, but don't fear! You can override that by manually setting the timezone in your secrets.py file. Plus, you can explicitly set your PyPortal to display a different time zone in case you have travel plans or a friend in Tokyo or something!

To do this, you'll add this line to your secrets file:

'timezone' : "America/Los_Angeles"

Here's a great list of valid timezones from the IANA Timezone Database. Head there to find the name of the one you want. Simply find the nearest timezone to your desired location, and use that name as displayed in the TZ database name column. 

Event Time

Since this is a one-time event, you'll need to tell the PyPortal when the event is, this is with respect to your local time so if its an event in another country or time zone, convert that to the local time where you are at. You can adjust the following variables to make this work:

  • EVENT_YEAR
  • EVENT_MONTH
  • EVENT_DAY
  • EVENT_HOUR
  • EVENT_MINUTE

For example, here's the countdown setting for PyCon:

Download: file
# The time of the thing!
EVENT_YEAR = 2019
EVENT_MONTH = 4
EVENT_DAY = 15
EVENT_HOUR = 9
EVENT_MINUTE = 0

Note that EVENT_HOUR is in 24-hour time so it will range from 00 to 23

Font

Then, it displays the info with bitmapped fonts to overlay on top of the background. You can learn more about converting type in this guide.

Now, the PyPortal will display the background and countdown until it reaches the event! When the event time arrives, you'll be treated with the other countdown_event.bmp image. Look, there's Dan, Kattni, and Scott just as they may appear at PyCon!*

*Blinka does not currently plan on attending the event. Some restrictions apply, see site for details.

Customization

If you like, you can also customize the background for a different event, by making your own 320x240 16-bit RGB color .bmp file. Then, adjust your setting to match the new event's time.

Graphics

Let's have a look at how the code places the elements on screen. Below, we can see the text items that are displayed.

Text Position

Depending on the design of your background bitmap and the length of the text you're displaying, you may want to reposition the text and caption.

The PyPortal's display is 320 pixels wide and 240 pixels high. In order to refer to those positions on the screen, we use an x/y coordinate system, where x is horizontal and y is vertical.

The origin of this coordinate system is the upper left corner. This means that a pixel placed at the upper left corner would be (0,0) and the lower right corner would be (320, 240).

Text Color

Another way to customize your display is to adjust the color of the text. The line text_color=0xFFFFFF in the constructor shows how. You will need to use the hexadecimal value for any color you want to display.

You can use something like https://htmlcolorcodes.com/ to pick your color and then copy the hex value, in this example it would be 0x0ED9EE

So, in order to customize the position and color of the text, you would adjust the values in these lines of code in code.py:

Download: file
    days_position = (8, 207)
hours_position = (110, 207)
minutes_position = (220, 207)
text_color = 0xFFFFFF
  

3D Printed Stand

If you'd like to create a 3D printed stand for your PyPortal Countdown Clock, you can follow the general instructions in this guide, but use the horizontal PyPortal Stand model linked here.

Use the four sets of standoffs and screws to fasten them together as shown.

This guide was first published on Mar 13, 2019. It was last updated on Mar 13, 2019. This page (Code PyPortal with CircuitPython) was last updated on Aug 20, 2019.