# Stomp-Reactive Light Up Slippers
## Overview
https://youtu.be/mw8Vqz0XOlo
Turn every step into a burst of light with these interactive light-up children's animal slippers. A force-sensitive resistor tucked inside the insole detects steps, and instantly triggers animations across addressable NeoPixel LEDs, glowing in your favorite colors. As you walk, the slippers respond in real time—adding a playful, responsive layer of light to every step. Comfortable, customizable, and full of personality, this project brings wearable tech right to your child's feet.
This guide uses a Feather PropMaker RP2040 board, and we've included sample CircuitPython code to get you up and running. Customize the code to make the colors and animations exactly what you want them to be, and let your animal spirit shine through.
For two slippers you'll want to order two controllers, two resistors, two switches and two batteries. 1 meter (39 inches) of NeoPixels was enough to surround both of the little tyke slippers I made.
## Parts
Featured
### Adafruit RP2040 Prop-Maker Feather with I2S Audio Amplifier
[Adafruit RP2040 Prop-Maker Feather with I2S Audio Amplifier](https://www.adafruit.com/product/5768)
The Adafruit Feather series gives you lots of options for a small, portable, rechargeable microcontroller board. By picking a feather and stacking on a FeatherWing you can create advanced projects quickly. One popular combo is our [Feather M4](https://www.adafruit.com/product/3857)...
In Stock
[Buy Now](https://www.adafruit.com/product/5768)
[Related Guides to the Product](https://learn.adafruit.com/products/5768/guides)
Featured
### Round Force-Sensitive Resistor (FSR) - 0.3 ~ 10 Newton Force
[Round Force-Sensitive Resistor (FSR) - 0.3 ~ 10 Newton Force](https://www.adafruit.com/product/166)
FSRs are sensors that allow you to detect physical pressure, squeezing and weight. They are simple to use and low cost. This sensor is an Alpha MF01A-N-221-A01 with 1/2 diameter sensing region.
We used to stock the Interlink model 402 FSR - the Alpha version is almost half the price...
Out of Stock
[Buy Now](https://www.adafruit.com/product/166)
[Related Guides to the Product](https://learn.adafruit.com/products/166/guides)
Featured
### Adafruit Mini Skinny NeoPixel Digital RGB LED Strip 1m
[Adafruit Mini Skinny NeoPixel Digital RGB LED Strip 1m](https://www.adafruit.com/product/2963)
So thin. So mini. So teeeeeeny-tiny. It's like the child sized version of our classic NeoPixel strips!
These NeoPixel strips have 60 digitally-addressable pixel Mini LEDs per meter and are very affordable and are only 7.5 mm wide, 5 mm if you remove the strip from...
In Stock
[Buy Now](https://www.adafruit.com/product/2963)
[Related Guides to the Product](https://learn.adafruit.com/products/2963/guides)
Featured
### JST 2-pin Extension Cable with On/Off Switch - JST PH2
[JST 2-pin Extension Cable with On/Off Switch - JST PH2](https://www.adafruit.com/product/3064)
By popular request - we now have a way you can turn on-and-off Lithium Polymer batteries without unplugging them.
This **PH2 Female/Male JST 2-pin Extension Cable ** comes with an in-line **Switch** - click once to turn on, click again to turn off....
In Stock
[Buy Now](https://www.adafruit.com/product/3064)
[Related Guides to the Product](https://learn.adafruit.com/products/3064/guides)
### Lithium Ion Battery - 3.7V 2000mAh
quantity: 2
[Lithium Ion Battery - 3.7V 2000mAh](https://www.adafruit.com/product/2011)
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 2000mAh. If you need a larger (or smaller!) battery,
In Stock
[Buy Now](https://www.adafruit.com/product/2011)
[Related Guides to the Product](https://learn.adafruit.com/products/2011/guides)
### Silicone Cover Stranded-Core Wire - 2m 26AWG Red
quantity: 3
[Silicone Cover Stranded-Core Wire - 2m 26AWG Red](https://www.adafruit.com/product/1877)
Silicone-sheathing wire is super-flexible and soft, and its also strong! Able to handle up to 200°C and up to 600V, it will do when PVC covered wire wimps out. We like this wire for being extremely supple and flexible, so it is great for wearables or projects where the wire-harness has to...
In Stock
[Buy Now](https://www.adafruit.com/product/1877)
[Related Guides to the Product](https://learn.adafruit.com/products/1877/guides)
## Additional Tools & Materials
- Animal Slippers! [I ordered these](https://www.amazon.com/dp/B0FV616XCS?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1&psc=1) - the eyes light up already for extra punch
- Needle & thread
- Seam ripper
- Soldering iron & accessories
- Hot glue gun
# Stomp-Reactive Light Up Slippers
## CircuitPython
[CircuitPython](https://github.com/adafruit/circuitpython) is a derivative of [MicroPython](https://micropython.org) designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the **CIRCUITPY** drive to iterate.
## CircuitPython Quickstart
Follow this step-by-step to quickly get CircuitPython running on your board.
[Download the latest version of CircuitPython for this board via circuitpython.org](https://circuitpython.org/board/adafruit_feather_rp2040_prop_maker/)
**Click the link above to download the latest CircuitPython UF2 file.**
Save it wherever is convenient for you.
To enter the bootloader, hold down the **BOOT/**** BOOTSEL button**(highlighted in red above), and while continuing to hold it (don't let go!), press and release the**reset button**(highlighted in red or blue above). **Continue to hold the BOOT/BOOTSEL button until the RPI-RP2 drive appears!**
If the drive does not appear, release all the buttons, and then repeat the process above.
You can also start with your board unplugged from USB, press and hold the BOOTSEL button (highlighted in red above), continue to hold it while plugging it into USB, and wait for the drive to appear before releasing the button.
A lot of people end up using charge-only USB cables and it is very frustrating! **Make sure you have a USB cable you know is good for data sync.**
You will see a new disk drive appear called **RPI-RP2**.
Drag the **adafruit\_circuitpython\_etc.uf2** file to **RPI-RP2.**
The **RPI-RP2** drive will disappear and a new disk drive called **CIRCUITPY** will appear.
That's it, you're done! :)
## Safe Mode
You want to edit your **code.py** or modify the files on your **CIRCUITPY** drive, but find that you can't. Perhaps your board has gotten into a state where **CIRCUITPY** is read-only. You may have turned off the **CIRCUITPY** drive altogether. Whatever the reason, safe mode can help.
Safe mode in CircuitPython does not run any user code on startup, and disables auto-reload. This means a few things. First, safe mode _bypasses any code in_ **boot.py** (where you can set **CIRCUITPY** read-only or turn it off completely). Second, _it does not run the code in_ **code.py**. And finally, _it does not automatically soft-reload when data is written to the_ **CIRCUITPY** _drive_.
Therefore, whatever you may have done to put your board in a non-interactive state, safe mode gives you the opportunity to correct it without losing all of the data on the **CIRCUITPY** drive.
### Entering Safe Mode
To enter safe mode when using CircuitPython, plug in your board or hit reset (highlighted in red above). Immediately after the board starts up or resets, it waits 1000ms. On some boards, the onboard status LED (highlighted in green above) will blink yellow during that time. If you press reset during that 1000ms, the board will start up in safe mode. It can be difficult to react to the yellow LED, so you may want to think of it simply as a slow double click of the reset button. (Remember, a fast double click of reset enters the bootloader.)
### In Safe Mode
If you successfully enter safe mode on CircuitPython, the LED will intermittently blink yellow three times.
If you connect to the serial console, you'll find the following message.
```terminal
Auto-reload is off.
Running in safe mode! Not running saved code.
CircuitPython is in safe mode because you pressed the reset button during boot. Press again to exit safe mode.
Press any key to enter the REPL. Use CTRL-D to reload.
```
You can now edit the contents of the **CIRCUITPY** drive. Remember, _your code will not run until you press the reset button, or unplug and plug in your board, to get out of safe mode._
## Flash Resetting UF2
If your board ever gets into a really _weird_ state and CIRCUITPY doesn't show up as a disk drive after installing CircuitPython, try loading this 'nuke' UF2 to RPI-RP2. which will do a 'deep clean' on your Flash Memory. **You will lose all the files on the board** , but at least you'll be able to revive it! After loading this UF2, follow the steps above to re-install CircuitPython.
[Download flash erasing "nuke" UF2](https://cdn-learn.adafruit.com/assets/assets/000/101/659/original/flash_nuke.uf2?1618945856)
# Stomp-Reactive Light Up Slippers
## 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.
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Ripple_Slippers/code.py
## 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_SECONDS` for effect length
- `PIXEL_BRIGHTNESS` for brightness
- `RIPPLE_DELAY` for ripple speed
- `TRAIL_FADE` for trail softness
- `COLOR_SEQUENCE` for your custom palette
These few settings let you completely change the mood of the animation without needing to dig into the full code logic.
```auto
# -----------------------------
# 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](https://share.google/soeYuqIjHHF8QDEz2).
# Stomp-Reactive Light Up Slippers
## Wiring Diagram
The NeoPixel strip attaches to the screw terminal as shown:
- +5v to +5v
- G to G
- DI to NEO
The force sensitive resistor gets connected into G and A0 - either side can go to either pin.
Plug your inline switch into the JST connector on the board, and plug the battery into the other end of the switch.
# Stomp-Reactive Light Up Slippers
## Electronics Assembly
Figure out how many pixels you need to wrap around the slippers. Mine fit 16 pixels each. Cut two lengths of LED strip to this length.
Cut the connector off the IN end of your NeoPixel strip. Usually this is the female connector, but verify you've got the correct end by looking for arrows on the strip itself -- they should be pointing away from the end you're working with.
Extend the red, black, and white wires by a few inches by soldering on a short length of wire to each. Cover the connections with heat shrink.
For the second slipper, solder these three wires directly to the copper pads on the strip: red to +, white to DI, and black to G.
If you need more help with this, check out our [How to Solder NeoPixels](https://learn.adafruit.com/make-it-glow-how-to-solder-neopixels-a-beginners-guide/soldering-strips) guide.
The trickiest part of this project is preparing the force sensitive resistor (FSR). These little leads are delicate and hard to solder, and it's easy to accidentally melt the plastic so take your time.
Tin both pads with a blob of solder. Cut a couple of 2-3" long wires and tin the ends of each as well. Put the wire in place and gently melt the solder on the pad and the wire at the same time, then hold it very still until the solder solidifies for a firm connection. Cover the connections with heat shrink or electrical tape to protect them from pulling out.
Solder the two wires into the holes marked **G** and **A0**. Insert the wires from the NeoPixel strip into the screw terminal as shown: red to **+5v** , black to **G** , and white to **NEO**.
Plug the switch into the JST connector on the Feather, and plug the battery into the other side of the switch. Flick the switch to "on" and the LEDs should light up with a quick red, green, blue "startup" sequence.
Tap on the force sensitive resistor (FSR) and the LED strip will light up with a ripple effect in the colors you chose in the code.
## Troubleshooting
If your strip isn't lighting up, here are a few things to try:
- Check that the pins you soldered to match the pins in the code. The FSR should be connected to **G** and **A0** , and the LED strip should be in the three rightmost screw terminals reading red, black, white from left to right.
- Be sure your battery is charged. Try plugging the battery directly into the JST port without the switch in between and make sure you get a status light on your board. If not, try powering from the USB port to see if you get different behavior.
- Try re-uploading the code. Check the serial monitor in your code editor to see if you're getting errors. ChatGPT or Claude can be helpful with debugging any errors you see.
- If you get a startup flash of red, green, blue but then nothing when you tap the sensor, then the sensor is likely the problem. Check to be sure you haven't bridged the pads with solder and that the plastic didn't get melted or the lines get broken. These things are super delicate!
- Be sure the wire connections into the screw terminal are secure.
# Stomp-Reactive Light Up Slippers
## Slipper Assembly
Use a thread ripper to open the back seam of the slippers. Go a couple inches along the sole seam on both sides. Pull out the foam insole.
Slip the LEDs into the sole, making sure the lights are facing outwards. Push the foam insole back in to hold them in place. I found it helpful to trim the foam just a little bit to make room for the pixel strip. Try to get the strip in there evenly, so the middle LED is placed right at the front of the slipper.
This is a little harder than it sounds. Turn the lights on once you have everything in place to make sure your LED strip is in there smoothly with no bumps or twists.
Slide the Feather into the right side of the slipper with the USB port facing the back (we need to be able to access it for battery charging), and the screw terminal facing outwards away from the feet. That terminal could make these slippers pretty uncomfortable if it's facing in and rubbing on tiny ankles.
Slip the FSR underneath the fabric lining and above the insole and secure it with a dab of hot glue when it's in striking range of little feet.
Slide the battery in on the left side, and slide in any extra wire from the switch. I found it easier to push the switch wire in first and slide the battery in afterwards.
Keep the switch out and accessible. Sew up the back seam and the sole side seams with a needle & strong thread -- I used heavy duty thread since these will probably take some abuse.
Use hot glue to secure the switch to the back of the slippers where it can be easily reached and pushed by little fingers.
Feel around for the USB port on the Feather. Use your thread ripper to cut a small hole in the fabric that will admit a USB cable for charging the batteries.
Test them out to be sure they are working, and get ready for light-up fun!
## Guide Products
### Adafruit RP2040 Prop-Maker Feather with I2S Audio Amplifier
[Adafruit RP2040 Prop-Maker Feather with I2S Audio Amplifier](https://www.adafruit.com/product/5768)
The Adafruit Feather series gives you lots of options for a small, portable, rechargeable microcontroller board. By picking a feather and stacking on a FeatherWing you can create advanced projects quickly. One popular combo is our [Feather M4](https://www.adafruit.com/product/3857)...
In Stock
[Buy Now](https://www.adafruit.com/product/5768)
[Related Guides to the Product](https://learn.adafruit.com/products/5768/guides)
### Round Force-Sensitive Resistor (FSR) - 0.3 ~ 10 Newton Force
[Round Force-Sensitive Resistor (FSR) - 0.3 ~ 10 Newton Force](https://www.adafruit.com/product/166)
FSRs are sensors that allow you to detect physical pressure, squeezing and weight. They are simple to use and low cost. This sensor is an Alpha MF01A-N-221-A01 with 1/2 diameter sensing region.
We used to stock the Interlink model 402 FSR - the Alpha version is almost half the price...
Out of Stock
[Buy Now](https://www.adafruit.com/product/166)
[Related Guides to the Product](https://learn.adafruit.com/products/166/guides)
### Adafruit Mini Skinny NeoPixel Digital RGB LED Strip 1m
[Adafruit Mini Skinny NeoPixel Digital RGB LED Strip 1m](https://www.adafruit.com/product/2963)
So thin. So mini. So teeeeeeny-tiny. It's like the child sized version of our classic NeoPixel strips!
These NeoPixel strips have 60 digitally-addressable pixel Mini LEDs per meter and are very affordable and are only 7.5 mm wide, 5 mm if you remove the strip from...
In Stock
[Buy Now](https://www.adafruit.com/product/2963)
[Related Guides to the Product](https://learn.adafruit.com/products/2963/guides)
### JST 2-pin Extension Cable with On/Off Switch - JST PH2
[JST 2-pin Extension Cable with On/Off Switch - JST PH2](https://www.adafruit.com/product/3064)
By popular request - we now have a way you can turn on-and-off Lithium Polymer batteries without unplugging them.
This **PH2 Female/Male JST 2-pin Extension Cable ** comes with an in-line **Switch** - click once to turn on, click again to turn off....
In Stock
[Buy Now](https://www.adafruit.com/product/3064)
[Related Guides to the Product](https://learn.adafruit.com/products/3064/guides)
### Lithium Ion Battery - 3.7V 2000mAh
[Lithium Ion Battery - 3.7V 2000mAh](https://www.adafruit.com/product/2011)
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 2000mAh. If you need a larger (or smaller!) battery,
In Stock
[Buy Now](https://www.adafruit.com/product/2011)
[Related Guides to the Product](https://learn.adafruit.com/products/2011/guides)
### Silicone Cover Stranded-Core Wire - 2m 26AWG Red
[Silicone Cover Stranded-Core Wire - 2m 26AWG Red](https://www.adafruit.com/product/1877)
Silicone-sheathing wire is super-flexible and soft, and its also strong! Able to handle up to 200°C and up to 600V, it will do when PVC covered wire wimps out. We like this wire for being extremely supple and flexible, so it is great for wearables or projects where the wire-harness has to...
In Stock
[Buy Now](https://www.adafruit.com/product/1877)
[Related Guides to the Product](https://learn.adafruit.com/products/1877/guides)
## Related Guides
- [Adafruit RP2040 Prop-Maker Feather](https://learn.adafruit.com/adafruit-rp2040-prop-maker-feather.md)
- [Halo Energy Sword RP2040](https://learn.adafruit.com/halo-energy-sword-rp2040.md)
- [Circuit Playground Bluefruit Pumpkin with Lights and Sounds ](https://learn.adafruit.com/pumpkin-with-circuit-playground-bluefruit.md)
- [Sound Reactive Paper Lanterns with LedFx](https://learn.adafruit.com/sound-reactive-paper-lanterns-with-led-fx.md)
- [PropMaker Jack O'Lantern](https://learn.adafruit.com/propmaker-jack-o-lantern.md)
- [Unicorn Hat with Moving Ears](https://learn.adafruit.com/unicorn-hat-with-moving-ears.md)
- [Touch Tone Phone Dial-a-Song](https://learn.adafruit.com/touch-tone-phone-dial-a-song.md)
- [PyLeap ESP32-S3 TFT Boxing Glove Tracker w/ Adafruit IO](https://learn.adafruit.com/esp32-s2-tft-boxing-glove-tracker-w-adafruit-io.md)
- [Halloween Skeleton Transformation Illusion Prop](https://learn.adafruit.com/halloween-skeleton-transformation-illusion-prop.md)
- [LED Snowboard with Motion-Reactive Animation](https://learn.adafruit.com/led-snowboard-with-motion-reactive-animation.md)
- [Zelda Echoes Of Wisdom Tri Rod](https://learn.adafruit.com/zelda-tri-rod.md)
- [Bubble Table with LED Animations and IR Remote Control](https://learn.adafruit.com/bubble-table-with-led-animations-and-ir-remote-control.md)
- [Bricktunes: LEGO Synthesizer Glove](https://learn.adafruit.com/bricktunes-lego-glove-synthesizer.md)
- [ESP32-S2 Reverse TFT Digital Clock Display featuring Blanka-chan!](https://learn.adafruit.com/esp32-s2-tft-digital-clock-display-featuring-blanka-chan.md)
- [LED NeoPixel Corset with Circuit Playground Express and MakeCode](https://learn.adafruit.com/led-corset-with-circuit-playground-and-makecode.md)
- [Motion Sensor Bat](https://learn.adafruit.com/motion-sensor-bat.md)