Code the Slippers
Once you've finished setting up your RP2040 Prop-Maker Feather with CircuitPython, you can access the code and necessary libraries by downloading the Project Bundle.
To do this, click on the Download Project Bundle button in the window below. It will download to your computer as a zipped folder.
# SPDX-FileCopyrightText: 2026 Erin St Blaine for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import time
import board
import digitalio
import neopixel
# =========================================================
# Ripple Footstep Lights with Color Cycling
# Pylint-friendly version
#
# What this project does:
# - Reads an FSR on pin A0
# - Triggers a ripple of light from the center of the strip
# - Changes color on each new press
# - If pressed again while running:
# - the timer extends
# - the color changes immediately
# - the ripple restarts from the center
# =========================================================
# -----------------------------
# USER SETTINGS
# -----------------------------
NUM_PIXELS = 20
ACTIVE_SECONDS = 3.0
PIXEL_BRIGHTNESS = 0.3
# Lower = faster ripple, higher = slower ripple
RIPPLE_DELAY = 0.05
# Lower = shorter trail, higher = longer trail
TRAIL_FADE = 0.6
# End fade settings
FADE_DELAY = 0.03
FADE_STEPS = 20
# Color cycle: white -> pink -> purple -> blue
COLOR_SEQUENCE = [
(255, 255, 255), # white
(255, 100, 180), # pink
(180, 0, 255), # purple
(0, 120, 255), # blue
]
print("boot")
# -----------------------------
# SENSOR SETUP
# -----------------------------
# FSR wired between A0 and GND.
# With internal pull-up enabled:
# - unpressed = True
# - pressed = False
motion = digitalio.DigitalInOut(board.A0)
motion.direction = digitalio.Direction.INPUT
motion.pull = digitalio.Pull.UP
print("motion ready")
# -----------------------------
# EXTERNAL POWER SETUP
# -----------------------------
# The Prop-Maker Feather needs EXTERNAL_POWER enabled
# to power the external NeoPixel terminal.
external_power = digitalio.DigitalInOut(board.EXTERNAL_POWER)
external_power.direction = digitalio.Direction.OUTPUT
external_power.value = True
print("external power enabled")
# -----------------------------
# NEOPIXEL SETUP
# -----------------------------
pixels = neopixel.NeoPixel(
board.EXTERNAL_NEOPIXELS,
NUM_PIXELS,
brightness=PIXEL_BRIGHTNESS,
auto_write=False
)
print("pixels ready")
# -----------------------------
# HELPER FUNCTIONS
# -----------------------------
def clear():
"""Turn all pixels off."""
pixels.fill((0, 0, 0))
pixels.show()
def dim_rgb(rgb_value, factor):
"""Return a dimmed version of an RGB color tuple."""
return (
int(rgb_value[0] * factor),
int(rgb_value[1] * factor),
int(rgb_value[2] * factor),
)
def get_next_color(sequence_index):
"""
Advance to the next color in the sequence.
Returns:
tuple: (new_index, new_rgb)
"""
new_index = (sequence_index + 1) % len(COLOR_SEQUENCE)
return new_index, COLOR_SEQUENCE[new_index]
def ripple_frame(center_pixel, radius, ripple_rgb):
"""
Draw one frame of the ripple animation.
center_pixel: where the ripple starts
radius: how far the wave has expanded
ripple_rgb: current ripple color
"""
for pixel_index in range(NUM_PIXELS):
distance = abs(pixel_index - center_pixel)
# Bright wave front
if distance == radius:
pixels[pixel_index] = ripple_rgb
# Optional thicker wave front:
# Uncomment these two lines and comment out the line above
# if abs(distance - radius) <= 1:
# pixels[pixel_index] = ripple_rgb
# Fade the trail behind the wave
elif distance < radius:
red, green, blue = pixels[pixel_index]
pixels[pixel_index] = (
int(red * TRAIL_FADE),
int(green * TRAIL_FADE),
int(blue * TRAIL_FADE),
)
# Pixels ahead of the wave stay off
else:
pixels[pixel_index] = (0, 0, 0)
pixels.show()
def ripple_for(seconds, start_rgb, starting_index):
"""
Run the ripple animation for a set amount of time.
If the sensor is pressed again while the animation is running:
- extend the timer
- change to the next color
- restart the ripple from the center
Returns:
int: updated color sequence index
"""
center_pixel = NUM_PIXELS // 2
active_rgb = start_rgb
sequence_index = starting_index
end_time = time.monotonic() + seconds
was_pressed = False
radius = 0
while time.monotonic() < end_time:
is_pressed = not motion.value
# Detect a new press during the active animation
if is_pressed and not was_pressed:
sequence_index, active_rgb = get_next_color(sequence_index)
print("extended, new color:", active_rgb)
end_time = time.monotonic() + seconds
radius = 0
ripple_frame(center_pixel, radius, active_rgb)
radius += 1
if radius > NUM_PIXELS:
radius = 0
time.sleep(RIPPLE_DELAY)
was_pressed = is_pressed
return sequence_index
def fade_out():
"""Fade the current pixels smoothly to black."""
current_pixels = [pixels[pixel_index] for pixel_index in range(NUM_PIXELS)]
for step in range(FADE_STEPS, -1, -1):
factor = step / FADE_STEPS
for pixel_index in range(NUM_PIXELS):
pixels[pixel_index] = dim_rgb(current_pixels[pixel_index], factor)
pixels.show()
time.sleep(FADE_DELAY)
clear()
# -----------------------------
# STARTUP FLASH
# -----------------------------
startup_colors = [
(255, 0, 0),
(0, 255, 0),
(0, 0, 255),
]
for startup_rgb in startup_colors:
pixels.fill(startup_rgb)
pixels.show()
time.sleep(0.2)
clear()
print("starting loop")
# -----------------------------
# MAIN LOOP
# -----------------------------
last_state = motion.value
current_sequence_index = -1
while True:
current_state = motion.value
if current_state != last_state:
print("changed:", current_state)
# Trigger on press: True -> False
if not current_state:
print("TRIGGERED")
current_sequence_index, trigger_rgb = get_next_color(
current_sequence_index
)
print("color:", trigger_rgb)
current_sequence_index = ripple_for(
ACTIVE_SECONDS,
trigger_rgb,
current_sequence_index
)
fade_out()
last_state = current_state
time.sleep(0.01)
Upload the Code and Libraries to the RP2040 Prop-Maker Feather
After downloading the Project Bundle, plug your RP2040 Prop-Maker Feather into the computer's USB port with a known good USB data+power cable. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called CIRCUITPY. Unzip the folder and copy the following items to the RP2040 Prop-Maker Feather's CIRCUITPY drive.
- lib folder
- code.py
Your RP2040 Prop-Maker Feather CIRCUITPY drive should look like this after copying the lib folder, and the code.py file.
Customizing the Ripple Slippers Code
This code is designed so you can change the overall look and feel of the effect without needing to rewrite the animation logic. Most of the creative control lives near the top of the file in the settings section.
The easiest ways to personalize the effect are:
-
ACTIVE_SECONDSfor effect length -
PIXEL_BRIGHTNESSfor brightness -
RIPPLE_DELAYfor ripple speed -
TRAIL_FADEfor trail softness -
COLOR_SEQUENCEfor your custom palette
These few settings let you completely change the mood of the animation without needing to dig into the full code logic.
# -----------------------------
# USER SETTINGS
# -----------------------------
NUM_PIXELS = 20
ACTIVE_SECONDS = 3.0
PIXEL_BRIGHTNESS = 0.3
# Lower = faster ripple, higher = slower ripple
RIPPLE_DELAY = 0.05
# Lower = shorter trail, higher = longer trail
TRAIL_FADE = 0.6
# End fade settings
FADE_DELAY = 0.03
FADE_STEPS = 20
# Color cycle: white -> pink -> purple -> blue
COLOR_SEQUENCE = [
(255, 255, 255), # white
(255, 100, 180), # pink
(180, 0, 255), # purple
(0, 120, 255), # blue
]
Effect length
This value controls how long the ripple effect runs after each step.
The code is also set up so that if the sensor is triggered again while the animation is still running, the timer extends and the ripple restarts.
Brightness
This controls the overall LED brightness. A lower value saves battery and creates a softer glow, or a higher value makes more "pop".
Ripple Speed and Trail Length.
Change RIPPLE_DELAY to adjust how quickly the ripple moves out from the center, and change TRAIL_FADE to adjust the fade rate.
Final fade-out
At the end of each run, the animation fades gently to black. FADE_DELAY and FADE_STEPS control that fade.
Colors
Each color is written as:
(red, green, blue)with values from 0 to 255. Change the hex colors to your favorites. Here's a color picker on Google.
Page last edited April 22, 2026
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