Copy and paste the code below into the code.py file in your CIRCUITPY drive to light up the crown. This code borrows some elements from the CircuitPython Essentials: NeoPixels page. It has a few animations that are described in comments before each animation function.

# SPDX-FileCopyrightText: 2021 Charlyn Gonda for Adafruit Industries
#
# SPDX-License-Identifier: MIT
#
import time
import board
from rainbowio import colorwheel
import neopixel

pixel_pin = board.D4
num_pixels = 13

pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.3,
                           auto_write=False)

# Lights up the message letter by letter
def spell(color, wait):
    for i in range(num_pixels-1, -1, -1):
        pixels[i] = color
        time.sleep(wait)
        pixels.show()
    time.sleep(0.5)

# Lights up a word, given a startIndex and stopIndex
def show_word(startIndex, endIndex, color, wait):
    pixels.fill(OFF)
    pixels.show()
    time.sleep(0.1)

    for i in range(startIndex, endIndex-1, -1):
        pixels[i] = color

    pixels.show()
    time.sleep(wait)

# Lights up every even-numbered index
def alternate(color, wait):
    for i in range(num_pixels):
        if i % 2 == 0:
            pixels[i] = color
        else:
            pixels[i] = OFF
    pixels.show()
    time.sleep(wait)

# Lights up every odd-numbered index
def alternate_reverse(color, wait):
    for i in range(num_pixels):
        if i % 2 == 1:
            pixels[i] = color
        else:
            pixels[i] = OFF
    pixels.show()
    time.sleep(wait)

# Full rainbow!
def rainbow_cycle(wait):
    for j in range(255):
        for i in range(num_pixels):
            rc_index = (i * 256 // num_pixels) + j
            pixels[i] = colorwheel(rc_index & 255)
        pixels.show()
        time.sleep(wait)

RED = (255, 0, 0)
YELLOW = (255, 150, 0)
ORANGE = (255, 40, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
MAGENTA = (255, 0, 20)
JADE = (0, 255, 40)
OFF = (0, 0, 0)

ALT_WAIT = 0.5
CHASE_WAIT = 0.1
WORD_WAIT = 1

while True:
    # indices for "birthday" is from 12 - 5
    show_word(12, 5, MAGENTA, WORD_WAIT)

    # indices for "boss" is from 4 - 0
    show_word(4, 0, JADE, WORD_WAIT)

    # again!
    show_word(12, 5, ORANGE, WORD_WAIT)
    show_word(4, 0, YELLOW, WORD_WAIT)

    spell(GREEN, CHASE_WAIT)
    spell(CYAN, CHASE_WAIT)
    spell(PURPLE, CHASE_WAIT)

    alternate(JADE, ALT_WAIT)
    alternate_reverse(ORANGE, ALT_WAIT)

    alternate(MAGENTA, ALT_WAIT)
    alternate_reverse(BLUE, ALT_WAIT)

    alternate(PURPLE, ALT_WAIT)
    alternate_reverse(GREEN, ALT_WAIT)

    alternate(CYAN, ALT_WAIT)
    alternate_reverse(MAGENTA, ALT_WAIT)

    rainbow_cycle(0)
    rainbow_cycle(0)  # higher number, slower rainbow

You may notice that in the spell function, we loop over a range of numbers that are generated like this: range(num_pixels-1, -1, -1)

This means that we're starting from index 12 (since there are 13 pixels) and decrementing 1 every time we loop. We have to loop through the indices backwards because of how we're going to assemble the crown -- the first letter "B" ends up being lit by the last LED in the strip. The same backwards loop happens in the show_word function as well.

You should see all the NeoPixels light up when you successfully load this code! This will help us align the NeoPixels under the laser cut pieces in our final assembly.

This guide was first published on Nov 10, 2021. It was last updated on 2021-11-10 13:47:15 -0500.

This page (CircuitPython Code) was last updated on Nov 22, 2021.

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