Build a sci-fi inspired bike light using Adafruit Feather and NeoPixels. Use an RGB LED Button to cycle through different colors and animations. The button will actually match the colors of the NeoPixels!

3D Printed Headlight

This is a 3D printed a headlight for my bike. I designed a mounting plate to house a 24x NeoPixel ring and 7x NeoPixel Jewel. The headlight fixture was inspired by rocket boosters and jet engines. I had the idea of an illuminated edge band that wraps around a cylinder with an illuminated inner core. By combining black PLA and translucent PLA, you can mask out certain geometry while illuminating other elements. I've been meaning to design specifically for dual extrusion such as the Ultimaker 3 and this is what I came up with. 

Adafruit's Feather Platform

I wanted to use the Adafruit Feather platform because it's fully featured and expandable via the FeatherWing add-ons. With on-board USB charging, it makes it easy recharge the battery.    

Parts List

• Adafruit Feather M4 Express
• 24x NeoPixel Ring
• 7x NeoPixel Jewel
• 2200mAh battery
• On/Off Toggle Switch
• RGB LED Button 16mm

Hardware Supplies

• 7x M3 x 6mm (pan head)
• 4x M3 x 8mm (pan head)
• 4x M3 Nylon locknuts
• 4x M2.5 x 5mm (flat head)
• JST-PH 3-pin – Female
• JST-PH 3-pin – Male
• JST-PH 4-pin – Female
• JST-PH 4-pin – Male
• JST-PH 2-pin – Male
• JST-PH 2-pin – Female
• JST-PH Connector Kit
• M2.5 & M3 Screw Taps
• 28AWG Silicone Cover Stranded Ribbon Cable

Tools

List of handy things to assist in any project.

• Wire Strippers
• Wire Cutters
• Soldering Iron
• Solder Wire
• Panavise Jr.
• Third Helping Hands
• Monoprice Inventor II

Prerequisite Guides

If you're new to Adafruit Feather M4 Express, CircuitPython or soldering, take a moment to walk through the following guides to get you started.

• Adafruit Feather M4 Express Intro
• Welcome to Circuit Python
• NeoPixel Uber Guide
• Adafruit's Guide to Excellent Soldering

Circuit Diagram

This provides a visual reference for wiring of the components. They aren't true to scale, just meant to be used as reference. This diagrams was created using Fritzing software.

Adafruit Library for Fritzing

Use our Fritzing parts library to create circuit diagrams for your projects. Download the library or just grab the individual parts. Files are hosted on our github repo linked below.

Wired Connections

24 NeoPixel Ring

• Pin 6 from Feather to Data In on 24x NeoPixel Ring
• GND from Feather to GND on 24x NeoPixel Ring
• 3V from Feather to PWR on 24x NeoPixel Ring

7 NeoPixel Jewel

• PWR from NeoPixel Ring to PWR on NeoPixel Jewel
• GND from NeoPixel Ring to GND on NeoPixel Jewel
• Data Out from NeoPixel Ring to Data In on NeoPixel Jewel

RGB LED Button

• Pin 9 from Feather to Red Cathode on RGB LED
• Pin 10 from Feather to Green Cathode on RGB LED
• Pin 11 from Feather to Blue Cathode on RGB LED
• 3V from Feather to Common Anode on RGB LED
• GND from Feather to Button
• Pin 12 from Feather to Button

Toggle Switch

• GND from Feather to Toggle Switch
• EN from Feather to Toggle Switch

Powering

The Adafruit Feather M4 Express can be powered via USB or JST using a 3.7v lipo battery. In this project, a 4400mAh lipo battery is used. The lipo battery is rechargeable via the USB port on the Adafruit Feather.

Setup Adafruit Feather M4 for CircuitPython

Your Feather M4 should already come with CircuitPython but maybe there's a new version, or you overwrote your board with Arduino code! In that case, see the below for how to reinstall or update CircuitPython. Otherwise you can skip this and proceed with the build.

CircuitPython Libraries

Install the Adafruit NeoPixel library for Circuit Python by downloading the latest bundle. Unzip the file and locate the needed libraries. Drop the libraries into a folder named "lib" on the CIRCUITPY drive.

For non-express boards like the Trinket M0 or Gemma M0, you'll need to manually install the necessary libraries from the bundle.

Required CircuitPython Libraries:

• neopixel
• adafruit_fancyled
• simpleio

Before continuing make sure your board's lib folder or root filesystem has the neopixel.mpy file was copied over.

Upload The Code

Copy and paste the code below into a new text document (we recommend using Mu as your editor, which is designed for CircuitPython.). Save the file and name it as main.py

Once the files has been uploaded to the drive, the board will automatically reboot and run the code.

Clips for Bike Frame

The headlight and box enclosure are designed to clamp onto the bike framing. There's a lot of different types of bikes, each with different sizes of framing. Take a moment to measure your bikes framing to ensure the clips will fit.

• Box clips: 38mm (1.5 inches) diameter
• Headlight clips: 23mm (0.9inches) diameter.

Dry Fit Parts

I suggest testing out the parts before installing the electronics. Print out the clips and try fitting them onto your bike frame. Fit the bhl-box-clip.stl parts onto the railing of the box enclosure – If the tolerances are too tight, use a filing tool to loosen up the edges. Fit the bhl-cover-jst.stl and bhl-cover-usb.stl parts onto the box enclosure.

Tap Mounting Holes

I used a set of screw taps to create threads in the various mounting holes. This greatly improves fastening screws. of the A mix of metric sizes are used here. M2.5 tap for the Feather mounting plate. M3 tap for the majority of the mounting holes.

Slice Settings

Use these settings as reference. Values listed were used in Ultimaker's CURA 3.X slicing software.

• 0.2mm Layer Height / 0.4mm nozzle
• 0.38mm Line Width (inner & outer widths)
• 60mm/s printing speed
• 20% infill

Glitter Infused Filament from Fillamentum

The material used to print the some of the parts in this project are from Fillamentum. From the PLA Extrafill line of filaments, Vertigo Galaxy PLA and  Rapunzel Silver PLA was used. Translucent PLA material was used to print the bhl-headlight-b.stl part.

Soldering NeoPixel Ring

The 3D printed mounting plate (bhl-plate.stl) for the 24 NeoPixel ring has a series of holes that exactly match the pinouts on the PCB.  Take a moment to line up the pins with those holes. The voltage, ground and data pins are labeled on the PCB. Insert wires from the 3-pin JST cable through the holes of the mounting plate. Use the holes that correspond with the 5V, GND and Data-In pins on the 24 NeoPixel ring. Pull the wires through the plate to gain enough length for soldering. The wires will need to be soldered to the bottom side of the PCB. A set of third helping hands can secure the ring in place while soldering. It's a bit tricky to solder the wires with the mounting plate attached so take precautions not to touch the plastic with the soldering iron.

Install NeoPixel Jewel

Insert the wires from the jewel through the center of the mounting plate. The center features holes that match exactly with the pinouts on the neopixel jewel. Line them up so they match. Press the PCB into the center so it's flush. Pull the wires all the way through the back of the mounting plate.

Solder NeoPixel Jewel

Grab the three wires from the jewel and thread them through the holes with corresponding pins. The 24 NeoPixel ring has spare voltage and ground pins that can be used. The Data In wire from the neopixel jewel needs to go to the Data Out pin on the neopixel ring.

Connecting NeoPixel Ring to NeoPixel Jewel

Ensure the connections from the neopixel jewel are going to the correct pins on neopixel ring. There should be enough wire length to reach the pins on the PCB. A set of third helping is essential in assisting with soldering. Otherwise, it's a bit tricky to keep the PCB in place. Be careful not to touch the mounting plate with the soldering iron.

Test NeoPixels

Before proceeding with the assembly, check the NeoPixels are wired correctly. I used a neopixel example code in circuit python to test out the NeoPixels. Be sure to update the code with the correct number of pixels and pin. Upload the code to the board if you haven't done so already. Plug in the battery to the Adafruit Feather to it test out.

Secure Mount to Headlight

Insert M3 x 8mm pan head metric machine screws through the holes on the mounting plate. Fasten the screws until it barely protrudes through the other side. Grab the headlight diffuser and line up the mounting holes. Press the parts together. While holding parts, fasten the screws to fully tighten.

Install Headlight Mounting Clips

Grab one of the clips and press it into one of the square shaped tabs on the mounting plate. Reference the photo to gauge the correct orientation. Insert an M3 lock nut into the recess on the mounting clip – The hexagon shape would allow the lock nut to be press fitted. Fasten a screw through the tab on the mounting plate. Repeat this process for the second tab.

Secure Feather to Mounting Plate

Flat head screws feature a chamfered edge. Pan head screws (sometimes called button heads) have flat surfaces that require adequate space. The mounting holes on the Feather PCB have very little spacing so a flat head screw is ideal. If a pan head screw is used, it will cover up components like the chip LEDs. We suggest using a M2.5 tapping tool to create threads in the mounting plate. 

Install Button

Insert the cables from the button into the large hole on the side of the box. Press the button into the hole until it becomes flush with the surface of the box. Grab the button's hex nut and insert it through the cables. Twist the hex nut onto the threading of the button. Fasten the hex nut until it's fully tightened. A set of needle nose plier can assist in grasping the hex nut.

Install Switch

Place the toggle switch inside the box and fit the stem of the switch through the smaller hole. Press the stem through so the body of the switch is flush. Insert the washer and hex nut onto the threading of the toggle switch. Hold the toggle switch in place while fastening the hex nut. Fasten until fully tightened. A pair of needle nose pliers can assist in grasping the hex nut.

Install Battery 

Inside the box enclosure is a circular clip that is sized for a 2200mAh battery. Grab the battery and begin to work it into the clip. Press the battery through the clip until it's fully enclosed in the box. Allow the JST-PH cable to sit outside the box.

Secure Feather Mount to Box

Grab the Feather mounting plate and orient it so the two mount holes line up with the ones on the box. The bottom of the mounting plate should face the side of the box with the mounting holes. Insert the mount and begin to push it inside the box with the USB port facing the outside. Reference the photo to get an idea of correct orientation. About halfway through, plug in the battery into the Feather. 

Attach Clips to Box

Grab the two clips for the box (bhl-box-clip.stl) and begin to attach them to the box enclosure. The box features a railing that allows the clips to slide into them. Orient the clips with the railing and firmly press it into place. Repeat this process for second clip on the opposite end of the box. If the tolerances are too tight, use a filing tool to loosen them up.

Bike Frame

Take a moment to consider where you'd like to attach the box. On my bike, I clamped it to the bike frame near the head tube. This way it's away from my knees and easily accessible.

Attach Box Clips

Grab hold of the tabs and carefully pull them apart to widen the opening. Press the clip onto the framing of the bike (38mm / 1.5in diameter tubing). The clips should clamp onto framing. Insert a M3 x 10mm pan head machine screw through the hole in the tab. Use an M3 nylon lock nut to secure the clips. A socket wrench or pliers can assist in grasping onto the locknut while fastening. Repeat this process for the second clip. 

Bike Handle Bar

Take a moment to consider where you'd like to attach the headlight. On my bike, I attached them to the lower part of the handlebars.

Attach Headlight Clips

Following a similar process, pull the tabs apart from the headlight clips and clamp it onto the tubing. You might find it easier to do one clip at a time. Use another set of M3 x 10mm screws and M3 lock nuts to secure the clips onto the tubing.