To use with CircuitPython, you need to first install a few libraries, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the directory MagTag_Kitchen_Timer/ and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your CIRCUITPY drive.
Your CIRCUITPY drive should now look similar to the following image:
# SPDX-FileCopyrightText: 2020 Eva Herrada for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import time
import terminalio
from adafruit_magtag.magtag import MagTag
magtag = MagTag()
magtag.peripherals.neopixel_disable = False
magtag.add_text(
text_font=terminalio.FONT,
text_position=(140, 55),
text_scale=7,
text_anchor_point=(0.5, 0.5),
)
magtag.set_text("00:00")
# Function that makes the neopixels display the seconds left
def update_neopixels(seconds):
n = seconds // 15
for j in range(n):
magtag.peripherals.neopixels[3 - j] = (128, 0, 0)
magtag.peripherals.neopixels[3 - n] = (int(((seconds / 15) % 1) * 128), 0, 0)
alarm_set = False
while True:
if not alarm_set:
# Set the timer to 1 minute
if magtag.peripherals.button_a_pressed:
alarm_time = 60
alarm_set = True
start = time.time()
magtag.set_text("01:00")
last_set = 60
magtag.peripherals.neopixels.fill((128, 0, 0))
# Set the timer to 5 minutes
elif magtag.peripherals.button_b_pressed:
alarm_time = 300
alarm_set = True
start = time.time()
magtag.set_text("05:00")
last_set = 300
magtag.peripherals.neopixels.fill((128, 0, 0))
# Set the timer to 20 minutes
elif magtag.peripherals.button_c_pressed:
alarm_time = 1200
alarm_set = True
start = time.time()
magtag.set_text("20:00")
last_set = 1200
magtag.peripherals.neopixels.fill((128, 0, 0))
else:
time.sleep(1)
remaining = alarm_time - (time.time() - start)
if (remaining < 0):
remaining = 0
print(remaining)
if remaining == 0:
magtag.peripherals.neopixels.fill((255, 0, 0))
# Play alarm and flash neopixels to indicate the timer is done
for i in range(2):
magtag.peripherals.neopixels.fill((255, 0, 0))
magtag.peripherals.play_tone(3000, 0.5)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((255, 0, 0))
magtag.peripherals.play_tone(3000, 0.5)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.5)
alarm_set = False
magtag.set_text("00:00")
last_set = 0
continue
update_neopixels(remaining % 60)
if remaining % 60 == 0 and remaining != last_set:
magtag.set_text("{:02d}:00".format(remaining // 60))
last_set = remaining
# Reset the timer
if magtag.peripherals.button_d_pressed:
time.sleep(0.1)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((255, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
alarm_set = False
magtag.set_text("00:00")
Code Behavior
I'll quickly explain how to use this because I recognize it may not be too obvious at first. To set an alarm, press one of the first three buttons. The first button sets a 1-minute alarm, the second one sets a 5-minute alarm, and the third one sets a 20-minute alarm, but you can change these values by making a few small edits in the code that I'll explain in the 'Code Run Through' section. The fourth button stops the current alarm, allowing the user to set a new one.
When the code is running, the number of minutes left will be displayed on the display. However, this only updates once a minute so the built-in NeoPixels are also used as indicators for the seconds. Each NeoPixel represents 15 seconds, so if there are 3 NeoPixels lit and the display says "05:00", there is between 5:30 and 5:45 left on the timer. The NeoPixel furthest to the right that is still illuminated will slowly dim so that at the end of the 15 seconds that it is indicating it will turn off.
import time import terminalio from adafruit_magtag.magtag import MagTag
Then, the code initializes the MagTag object and makes sure built-in NeoPixels are enabled.
magtag = MagTag() magtag.peripherals.neopixel_disable = False
After that, the text object is added to the center of the display and it is set to "00:00."
magtag.add_text(
text_font=terminalio.FONT,
text_position=(140, 55),
text_scale=7,
text_anchor_point=(0.5, 0.5),
)
magtag.set_text("00:00")
Now, the code defines a function, update_neopixels. This function takes the amount of seconds left in the current minute (so if there were 5 minutes and 33 seconds left in the timer, the function would be given 33) and dims one NeoPixel at a time. At 59 seconds, all 4 NeoPixels are fully illuminated. At 46 seconds, the NeoPixel furthest to the right is almost completely out but the other three are still fully illuminated, and when this function is given 45 seconds, it will turn the fourth NeoPixel off and start dimming the third one.
def update_neopixels(seconds):
n = seconds // 15
for j in range(n):
magtag.peripherals.neopixels[3 - j] = (128, 0, 0)
magtag.peripherals.neopixels[3 - n] = (int(((seconds / 15) % 1) * 128), 0, 0)
At this point, the main loop starts. It first checks to see if an alarm is currently active. If there isn't an active alarm, it starts scanning to see if a button is pressed. If button a, b, or c (first three buttons, going left to right) is pressed, it then activates an alarm and sets a few variables that make keeping track of the alarm easier.
If you want to change the time an alarm lasts, change alarm_time, the string in magtag.set_text, and last_set.
alarm_set = False
while True:
if not alarm_set:
# Set the timer to 1 minute
if magtag.peripherals.button_a_pressed:
alarm_time = 60
alarm_set = True
start = time.time()
magtag.set_text("01:00")
last_set = 60
magtag.peripherals.neopixels.fill((128, 0, 0))
# Set the timer to 5 minutes
elif magtag.peripherals.button_b_pressed:
alarm_time = 300
alarm_set = True
start = time.time()
magtag.set_text("05:00")
last_set = 300
magtag.peripherals.neopixels.fill((128, 0, 0))
# Set the timer to 20 minutes
elif magtag.peripherals.button_c_pressed:
alarm_time = 1200
alarm_set = True
start = time.time()
magtag.set_text("20:00")
last_set = 1200
magtag.peripherals.neopixels.fill((128, 0, 0))
This next part of the loop only gets executed when alarm_set is True, that is to say when an alarm is active. It starts by printing out the time left in the alarm (in seconds) to the serial console. Then, if the time remaining has reached zero, it plays an alarm through the speaker and flashes the NeoPixels on and off a few times to indicate that the alarm is done. Next, it sets the necessary variables to indicate that an alarm isn't set.
else:
time.sleep(1)
remaining = alarm_time - (time.time() - start)
if (remaining < 0):
remaining = 0
print(remaining)
if remaining == 0:
magtag.peripherals.neopixels.fill((255, 0, 0))
# Play alarm and flash neopixels to indicate the timer is done
for i in range(2):
magtag.peripherals.neopixels.fill((255, 0, 0))
magtag.peripherals.play_tone(3000, 0.5)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((255, 0, 0))
magtag.peripherals.play_tone(3000, 0.5)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.5)
alarm_set = False
magtag.set_text("00:00")
last_set = 0
continue
If there is still time left in the alarm, update_neopixels is called. The code then checks to see if there is a whole number of minutes left and if there is, updates the display to reflect that.
update_neopixels(remaining % 60)
if remaining % 60 == 0 and remaining != last_set:
magtag.set_text("{:02d}:00".format(remaining // 60))
last_set = remaining
Finally, the code checks to see if button D (furthest to the right) is being pressed. If it is, it flashes the NeoPixels a few times and resets the alarm.
# Reset the timer
if magtag.peripherals.button_d_pressed:
time.sleep(0.1)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((255, 0, 0))
time.sleep(0.1)
magtag.peripherals.neopixels.fill((0, 0, 0))
time.sleep(0.1)
alarm_set = False
magtag.set_text("00:00")
Page last edited January 21, 2025
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