NeoPixel Tiara

2022-09-16 | By Adafruit Industries

License: See Original Project Wearables Arduino Gemma

Guide by Becky Stern

Overview

You can make a crown of light for prom or your birthday this year! A few free-‎wired NeoPixels make you the cyber-pageant queen.‎

‎

For this project you will need:‎

Gemma M0 or GEMMA v2 wearable microcontroller (or build on ‎the GEMMA Starter Pack)
seven sewable NeoPixels (or any combination of pixels, NeoPixel rings, or ‎high-density NeoPixel strip) Use "RGB" NeoPixel rings, not "RGBW" type!
‎2x2032 coin cell battery holder and batteries or rechargeable Li-poly ‎battery
zip ties & hot glue
‎3D printed band, crown, or recycled stiff headband
solid core hookup wire
sharp wire strippers
sharp flush snips

Glamour shots by Andrew Tingle.‎

This guide was written for the Gemma v2 board but can be done with either the ‎v2 or Gemma M0. We recommend the Gemma M0 as it is easier to use and is ‎more compatible with modern computers!‎

Before you get started, follow the Gemma M0 guide or the Classic ‎Introducing GEMMA guide.

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Build it!‎

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This diagram uses the original Gemma, but you can also use the Gemma M0 with ‎the exact same wiring!‎

Above is the circuit diagram for the simple tiara. All ground pads are connected to ‎GND on GEMMA, likewise all power pads are connected to Vout on GEMMA, and ‎data lines are chained from D1 to the inward facing arrow on the first pixel, then ‎from each pixel's outward facing arrow to the next pixel's inward facing arrow.‎

Strip the insulation from a long piece of solid-core hookup wire and clip it to one ‎side of your headband. This will be the pixels' ground bus. ‎

Insert perpendicular wires through holes in the headband and curl their stripped ‎ends around the long ground bus wire. ‎

Crimp wire connections with pliers.‎

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Be sure wire connections are tidy enough to nest snugly against the hair band, ‎and solder connections in place.‎

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Trim wires to the silhouette you like, then strip the ends. Bend the stripped ends ‎over and hand the NeoPixels from them (through the pad marked -). Solder all ‎NeoPixels, making sure they're facing the same way.‎

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Next use bits of wire in the shape of staples to connect up the data lines.‎

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Solder wires from the + side of each pixel and cut to length. Strip the ends and ‎solder to one long power bus.‎

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Connect power, ground, and data lines to GEMMA at the input end of the pixel ‎chain. Plug in over USB and program it up! This basic sketch flashes the seven ‎pixels randomly:‎

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Get creative with your tiara design! This one uses a NeoPixel ring in the center, ‎and the wiring is barely different than above.‎

Arduino Code

The Arduino code presented below works equally well on all versions of GEMMA: ‎v2 and M0. But if you have an M0 board, consider using the CircuitPython code ‎on the next page of this guide, no Arduino IDE required!‎

Click to Download the NeoPixel Library

Installing Arduino libraries is a frequent stumbling block. If this is your first time, ‎or simply needing a refresher, please read the All About Arduino Libraries tutorial.‎ If the library is correctly installed (and the Arduino IDE is restarted), you should be ‎able to navigate through the “File” rollover menus as follows: ‎

File→Sketchbook→Libraries→Adafruit_NeoPixel→strandtest ‎

Connect up your NeoPixels in a solderless breadboard and use alligator clips to ‎attach to GEMMA, referring to the circuit diagram if necessary. ‎

You’ll need to change a few lines in the code regarding the data pin (1), type of ‎pixels (RGB vs GRB), and number of pixels (5). The resulting (and slightly simplified) ‎code is below:‎

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// SPDX-FileCopyrightText: 2017 Dano Wall for Adafruit Industries
// SPDX-FileCopyrightText: 2017 Becky Stern for Adafruit Industries
//
// SPDX-License-Identifier: MIT

//Random Flash animation for Neopixel circuits
//by Dano Wall and Becky Stern for Adafruit Industries
//based on the Sparkle Skirt, minus the accelerometer
#include <Adafruit_NeoPixel.h>

#define PIN 1

// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(7, PIN, NEO_GRB + NEO_KHZ800);

// Here is where you can put in your favorite colors that will appear!
// just add new {nnn, nnn, nnn}, lines. They will be picked out randomly
//                          R   G   B
uint8_t myColors[][3] = {{232, 100, 255},   // purple
                         {200, 200, 20},   // yellow 
                         {30, 200, 200},   // blue
                          };
                               
// don't edit the line below
#define FAVCOLORS sizeof(myColors) / 3

void setup() {
  strip.begin();
  strip.setBrightness(40);
  strip.show(); // Initialize all pixels to 'off'
}

void loop() {
flashRandom(5, 1);  // first number is 'wait' delay, shorter num == shorter twinkle
flashRandom(5, 3);  // second number is how many neopixels to simultaneously light up
flashRandom(5, 2);
}

void flashRandom(int wait, uint8_t howmany) {
 
  for(uint16_t i=0; i<howmany; i++) {
    // pick a random favorite color!
    int c = random(FAVCOLORS);
    int red = myColors[c][0];
    int green = myColors[c][1];
    int blue = myColors[c][2]; 
 
    // get a random pixel from the list
    int j = random(strip.numPixels());
    
    // now we will 'fade' it in 5 steps
    for (int x=0; x < 5; x++) {
      int r = red * (x+1); r /= 5;
      int g = green * (x+1); g /= 5;
      int b = blue * (x+1); b /= 5;
      
      strip.setPixelColor(j, strip.Color(r, g, b));
      strip.show();
      delay(wait);
    }
    // & fade out in 5 steps
    for (int x=5; x >= 0; x--) {
      int r = red * x; r /= 5;
      int g = green * x; g /= 5;
      int b = blue * x; b /= 5;
      
      strip.setPixelColor(j, strip.Color(r, g, b));
      strip.show();
      delay(wait);
    }
  }
  // LEDs will be off when done (they are faded to 0)
}

View on GitHub

From the Tools→Board menu, select the device you are using: ‎

Adafruit Gemma M0‎
Adafruit Gemma 8 MHz ‎

Connect the USB cable between the computer and your device. The original ‎Gemma (8 MHz) needs the reset button pressed on the board, then click the ‎upload button (right arrow icon) in the Arduino IDE. You do not need to press the ‎reset on the newer Gemma M0.‎

When the battery is connected, you should get a light show from the LEDs. All ‎your pixels working? Great! You can take apart this prototype and get ready to ‎put the pixels in the collar. Refer to the NeoPixel Uberguide for more info.‎

CircuitPython Code

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GEMMA M0 boards can run CircuitPython — a different approach to ‎programming compared to Arduino sketches. In fact, CircuitPython ‎comes factory pre-loaded on GEMMA M0. If you’ve overwritten it with an ‎Arduino sketch, or just want to learn the basics of setting up and using ‎CircuitPython, this is explained in the Adafruit GEMMA M0 guide.‎

These directions are specific to the “M0” GEMMA board. The original GEMMA ‎with an 8-bit AVR microcontroller doesn’t run CircuitPython…for those boards, ‎use the Arduino sketch on the “Arduino code” page of this guide.‎

Below is CircuitPython code that works similarly (though not exactly the same) as ‎the Arduino sketch shown on a prior page. To use this, plug the GEMMA M0 into ‎USB…it should show up on your computer as a small flash drive…then edit the file ‎‎“code.py” with your text editor of choice. Select and copy the code below and ‎paste it into that file, entirely replacing its contents (don’t mix it in with lingering ‎bits of old code). When you save the file, the code should start running almost ‎immediately (if not, see notes at the bottom of this page).‎

If GEMMA M0 doesn’t show up as a drive, follow the GEMMA M0 guide link ‎above to prepare the board for CircuitPython.‎

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# SPDX-FileCopyrightText: 2017 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time

import board
import neopixel

try:
    import urandom as random
except ImportError:
    import random

numpix = 7  # Number of NeoPixels
pixpin = board.D1  # Pin where NeoPixels are connected
strip = neopixel.NeoPixel(pixpin, numpix, brightness=1, auto_write=True)
colors = [
    [232, 100, 255],  # Purple
    [200, 200, 20],  # Yellow
    [30, 200, 200],  # Blue
]


def flash_random(wait, howmany):
    for _ in range(howmany):

        c = random.randint(0, len(colors) - 1)  # Choose random color index
        j = random.randint(0, numpix - 1)  # Choose random pixel
        strip[j] = colors[c]  # Set pixel to color

        for i in range(1, 5):
            strip.brightness = i / 5.0  # Ramp up brightness
            time.sleep(wait)

        for i in range(5, 0, -1):
            strip.brightness = i / 5.0  # Ramp down brightness
            strip[j] = [0, 0, 0]  # Set pixel to 'off'
            time.sleep(wait)


while True:
    # first number is 'wait' delay, shorter num == shorter twinkle
    flash_random(.01, 1)
    # second number is how many neopixels to simultaneously light up
    flash_random(.01, 3)
    flash_random(.01, 2)

View on GitHub

This code requires the neopixel.py library. A factory-fresh board will have this ‎already installed. If you’ve just reloaded the board with CircuitPython, create the ‎‎“lib” directory and then download neopixel.py from Github.‎

Download neopixel.py from GitHub

Wear it!‎

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Plug in a coin cell battery holder or rechargeable Li-poly battery! You can pin the ‎battery up into your hairdo or attach to the tiara with glue.‎‎ ‎

Glamour shots by Andrew Tingle.‎