Getting familiar with CircuitPython
CircuitPython is a programming language based on Python, one of the fastest growing programming languages in the world. It is specifically designed to simplify experimenting and learning to code on low-cost microcontroller boards.
CircuitPython is easiest to use within the Mu Editor. If you haven't previously used Mu, this guide will get you started.
Preparing your Board
1) Download the latest 4.0 library pack,
2) Unzip it the library pack and drag the adafruit_bus_device, adafruit_ds3231, adafruit_register, and neopixel libraries over into the /lib folder on CIRCUITPY.
If there is no lib directory on your CIRCUITPY drive, create one to put the file into.
More info on installing libraries can be found here.
Make sure you have the following libraries installed:
- adafruit_bus_device
- adafruit_ds3231
- adafruit_register
- neopixel
Setting the Time
First things first, let's tell the RTC FeatherWing what time it is!
Copy and paste the code below into Mu. In line 22, fill in the correct year, month, day, hour, and minute. Save this as code.py to your CIRCUITPY device.
(More details on using the DS3231 Precision RTC can be found in this guide)
# SPDX-FileCopyrightText: 2019 Limor Fried for Adafruit Industries
# SPDX-FileCopyrightText: 2019 Anne Barela for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# Write the time for the Adafruit DS3231 real-time clock.
# Limor Fried/Anne Barela for Adafruit Industries
import time
import board
import busio as io
import digitalio
import adafruit_ds3231
i2c = io.I2C(board.SCL, board.SDA)
# Create the RTC instance:
rtc = adafruit_ds3231.DS3231(i2c)
LED13 = digitalio.DigitalInOut(board.D13)
LED13.direction = digitalio.Direction.OUTPUT
# pylint: disable-msg=using-constant-test
if True:
# year, mon, date, hour, min, sec, wday, yday, isdst
t = time.struct_time((2019, 7, 10, 17, 00, 0, 0, -1, -1))
# you must set year, mon, date, hour, min, sec and weekday
# yearday is not supported
# isdst can be set but we don't do anything with it at this time
print("Setting time to:", t) # uncomment for debugging
rtc.datetime = t
print("Done!")
LED13.value = True
# pylint: enable-msg=using-constant-test
Once the time has been set we're ready to move on to uploading the Wordclock code.
Vertical Wordclock Code
Make sure you've connected the Feather M4 Express to your computer (mac/PC/Linux) via a known good USB A to micro-B cable. Your board should show up as a flash disk drive named CIRCUITPY (If you see a disk name FEATHERBOOT, try pressing the reset button again. If the only drive name you get is named FEATHERBOOT, CircuitPython may not be loaded on the board. You can load CircuitPython as per this guide).
Once your board is connected, copy the code below from the window below to a file on the Feather CIRCUITPY drive as code.py. You can select Download in the upper left to save the code onto your computer.
# SPDX-FileCopyrightText: 2019 Anne Barela for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# Vertical Word Clock using the Adafruit Feather M4 and
# the Adafruit DS3231 real-time clock FeatherWing
import time
import board
import busio as io
import digitalio
import adafruit_ds3231
import neopixel
i2c = io.I2C(board.SCL, board.SDA)
# Create the RTC instance:
rtc = adafruit_ds3231.DS3231(i2c)
# Set up Feather M4 onboard LED for output
LED13 = digitalio.DigitalInOut(board.D13)
LED13.direction = digitalio.Direction.OUTPUT
# Set digital 6 as an input for slide switch
Slide_Switch = digitalio.DigitalInOut(board.D6)
Slide_Switch.switch_to_input(pull=digitalio.Pull.UP)
pixel_pin = board.D5
num_pixels = 21
pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=1.0,
auto_write=False)
pixels.fill((0, 0, 0)) # Blanking Display
COLOR = (0, 200, 0) # Green for time later in code
# Bitmap values for each value. These can be OR'ed together
THREE = 1
EIGHT = 1 << 1
ELEVEN = 1 << 2
TWO = 1 << 3
SIX = 1 << 4
FOUR = 1 << 5
SEVEN = 1 << 6
NOON = 1 << 7
TEN = 1 << 8
ONE = 1 << 9
FIVE = 1 << 10
MIDNIGHT = 1 << 11
NINE = 1 << 12
PAST = 1 << 13
TO = 1 << 14
FIVEMIN = 1 << 15
QUARTER = 1 << 16
TENMIN = 1 << 17
HALF = 1 << 18
TWENTY = 1 << 19
# Pass in hour and minute, return LED bitmask
# pylint: disable=too-many-branches
# pylint: disable=too-many-statements
def writetime(the_hr, the_min):
value = 0 # Start with zero, which is no words
if (the_hr == 24) and (the_min == 0): # Special cases: Midnight and Noon
return MIDNIGHT
if (the_hr == 12) and (the_min == 0):
return NOON
# set minute
if (the_min > 3) and (the_min < 8):
value = value | FIVEMIN
if (the_min > 7) and (the_min < 13):
value = value | TENMIN
if (the_min > 12) and (the_min < 18):
value = value | QUARTER
if (the_min > 17) and (the_min < 23):
value = value | TWENTY
if (the_min > 22) and (the_min < 28):
value = value | TWENTY | FIVEMIN
if (the_min > 27) and (the_min < 33):
value = value | HALF
if (the_min > 32) and (the_min < 38):
value = value | TWENTY | FIVEMIN
if (the_min > 37) and (the_min < 43):
value = value | TWENTY
if (the_min > 42) and (the_min < 48):
value = value | QUARTER
if (the_min > 47) and (the_min <= 53):
value = value | TENMIN
if the_min >= 54:
value = value | FIVEMIN
# before or after
if (the_min > 3) and (the_min <= 32):
value = value | PAST
if the_min >= 33:
the_hr = the_hr + 1 # for the TO case
value = value | TO
# set hour
if the_hr > 12:
the_hr = the_hr - 12 # Convert 24 hour format to 12 hour
if the_hr == 1:
value = value | ONE
if the_hr == 2:
value = value | TWO
if the_hr == 3:
value = value | THREE
if the_hr == 4:
value = value | FOUR
if the_hr == 5:
value = value | FIVE
if the_hr == 6:
value = value | SIX
if the_hr == 7:
value = value | SEVEN
if the_hr == 8:
value = value | EIGHT
if the_hr == 9:
value = value | NINE
if the_hr == 10:
value = value | TEN
if the_hr == 11:
value = value | ELEVEN
if the_hr == 0:
value = value | MIDNIGHT
if the_hr == 12:
value = value | NOON
return value
# end def
# pylint: enable=too-many-branches
# pylint: enable=too-many-statements
# Main loop
LEDstate = 0
Write_Now = True
while True:
t = rtc.datetime
# print("The date is {} {}/{}/{}".format(days[int(t.tm_wday)],
# t.tm_mday, t.tm_mon, t.tm_year))
# print("The time is {}:{:02}:{:02}".format(t.tm_hour, t.tm_min, t.tm_sec))
hour = t.tm_hour
if not Slide_Switch.value: # Slide switch activate = Daylight savings
# print("Switch detected for daylight savings")
if hour == 24:
hour = 1
else:
hour += 1
Write_Now = True # Trigger a write
minute = t.tm_min
second = t.tm_sec
if second == 59 or Write_Now:
# print("The time is {}:{:02}".format(t.tm_hour, t.tm_min))
pixels.fill((0, 0, 0)) # blank all pixels for change
the_time = writetime(hour, minute)
for i in range(0, 21): # Check all bits
if the_time & 1 << i: # If the bit is true
pixels[i+1] = COLOR # set pixel on (shift up 2 for buried one)
pixels.show()
if LEDstate == 0: # Flash the D13 LED every other second for activity
LED13.value = True
LEDstate = 1
else:
LED13.value = False
LEDstate = 0
Write_Now = False
time.sleep(1) # wait a second
Open the code up in the Mu editor. Press the Save button and your code should automatically be saved to the CIRCUITPY disk drive (which appears when the Feather M4 Express is plugged into your computer) as code.py.
Making Changes
If you'd like to adjust the color of your clock, this can be changed in line 29 of the code. Simply change the numbers in COLOR = (0, 200, 0) (green) - make the clock glow blue (0, 0, 200) or red (200, 0, 0), or any color in between! A great color picker is at https://www.w3schools.com/colors/colors_picker.asp.
Page last edited January 20, 2025
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