Author: Danli Zeng

🎃 Result Photos

The result looks great and I’m really proud of this first cosplaying & Halloween parade attempt!! The character is Medusa Gorgon from Soul Eater (the anime) and the goal was to create replicates of her arrows that pair well with the costume. The purple fading light at the arrow heads turned out to be a perfect point of direction for my big classmate group at the parade too and I was recognized by the standby audience. 🥳🥳🥳

What Medusa and Dr. Stein looks like in Soul Eater:

📷Process photos

📘Reason of making

I wanted to cosplay Medusa from Soul Eater and thought NeonPixel and basic Arduino would be the best tools to product a glowing arrow effect, which by itself is a good wearable to wear around the waist and extend from behind.

🎩 How to wear

The plan was to attach 6 arrows around a waist band vertically to prevent sliding but I fell sick half of the week and only got to get 2 arrows done. Becky suggested it is common practice for cosers to wear the gears with a small backpack and that’s what I did with my costume in black. I basically shoveled the root of the arrows, connected to the Gemma M0 board and a power bank, into my backpack. I then fastened the structure by bending and securing the body of the arrow onto the shoulder belts as well as with tightened zippers. It turned out to be pretty sturdy and well.

• Improved soldering skills on tiny LEDs
• Improvising with material to achieve great outcomes
• Basic Arduino coding

💭 What I would do differently

• Plan better and order side LEDs earlier so to reserve more time to the most tedious soldering & wiring process

🧱 Materials

• LEDs
• Gemma M0
• wires (blue, red, black)
• soldering supplies
• black foam tube (1 1/4” inner diameter)
• blue foam
• black acrylic paint

🔌 Circuit Diagram

(Will upload tomorrow morning)

⌨️ Arduino Code

// NeoPixel test program showing use of the WHITE channel for RGBW
// pixels only (won't look correct on regular RGB NeoPixel strips).

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
 #include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif

// Which pin on the Arduino is connected to the NeoPixels?
// On a Trinket or Gemma we suggest changing this to 1:
#define LED_PIN     1

// How many NeoPixels are attached to the Arduino?
#define LED_COUNT  25

// NeoPixel brightness, 0 (min) to 255 (max)
#define BRIGHTNESS 50 // Set BRIGHTNESS to about 1/5 (max = 255)

// Declare our NeoPixel strip object:
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
// Argument 1 = Number of pixels in NeoPixel strip
// Argument 2 = Arduino pin number (most are valid)
// Argument 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)
//   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)

void setup() {
  // These lines are specifically to support the Adafruit Trinket 5V 16 MHz.
  // Any other board, you can remove this part (but no harm leaving it):
#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000)
  clock_prescale_set(clock_div_1);
#endif
  // END of Trinket-specific code.

  strip.begin();           // INITIALIZE NeoPixel strip object (REQUIRED)
  strip.show();            // Turn OFF all pixels ASAP
  strip.setBrightness(BRIGHTNESS);
  Serial.begin(9600);
  colorWipe(strip.Color(0,   0,   0, 0)     , 0); 
}

void loop() {
  // Fill along the length of the strip in various colors...
  /*
  
  colorWipe(strip.Color(  0, 255,   0)     , 50); // Green
  colorWipe(strip.Color(  0,   0, 255)     , 50); // Blue
  colorWipe(strip.Color(  0,   0,   0, 255), 50); // True white (not RGB white)

  whiteOverRainbow(75, 5);

  pulseWhite(5);

  rainbowFade2White(3, 3, 1);
  */
  fadeToPurple(120);
}


void fadeToPurple(int wait) {
  //for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
    //strip.setPixelColor(i, color);         //  Set pixel's color (in RAM)
    // fade in from min to max in increments of 5 points:
    for (int fadeValue = 0; fadeValue <= 255; fadeValue += 5) {
    // sets the value (range from 0 to 255):
        colorAll(strip.Color(fadeValue,   0,   fadeValue,0), 0);

    //strip.setPixelColor(i, strip.Color(fadeValue,   0,   255,0));
   // analogWrite(ledPin, fadeValue);
    // wait for 30 milliseconds to see the dimming effect
    delay(40);
    Serial.print("fadevalue= ");
    Serial.println(fadeValue);
      strip.show();                          //  Update strip to match
  }

  // fade out from max to min in increments of 5 points:
  for (int fadeValue = 255; fadeValue >= 0; fadeValue -= 3) {
    // sets the value (range from 0 to 255):
    colorAll(strip.Color(fadeValue,   0,   fadeValue,0), 0);
    //strip.setPixelColor(i, strip.Color(fadeValue,   0,   255,0));
    // wait for 30 milliseconds to see the dimming effect
    delay(40);
  Serial.print("fadevalue= ");
    Serial.println(fadeValue);  }
  strip.show();                          //  Update strip to match
  
//}
//delay(wait);
}


// Fill strip pixels one after another with a color. Strip is NOT cleared
// first; anything there will be covered pixel by pixel. Pass in color
void colorAll(uint32_t color, int wait) {
  for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
    strip.setPixelColor(i, color);         //  Set pixel's color (in RAM)
  }
    strip.show();                          //  Update strip to match
    delay(wait);                           //  Pause for a moment
}
// (as a single 'packed' 32-bit value, which you can get by calling
// strip.Color(red, green, blue) as shown in the loop() function above),
// and a delay time (in milliseconds) between pixels.
void colorWipe(uint32_t color, int wait) {
  for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
    strip.setPixelColor(i, color);         //  Set pixel's color (in RAM)
    strip.show();                          //  Update strip to match
    delay(wait);                           //  Pause for a moment
  }
}

void whiteOverRainbow(int whiteSpeed, int whiteLength) {

  if(whiteLength >= strip.numPixels()) whiteLength = strip.numPixels() - 1;

  int      head          = whiteLength - 1;
  int      tail          = 0;
  int      loops         = 3;
  int      loopNum       = 0;
  uint32_t lastTime      = millis();
  uint32_t firstPixelHue = 0;

  for(;;) { // Repeat forever (or until a 'break' or 'return')
    for(int i=0; i<strip.numPixels(); i++) {  // For each pixel in strip...
      if(((i >= tail) && (i <= head)) ||      //  If between head & tail...
         ((tail > head) && ((i >= tail) || (i <= head)))) {
        strip.setPixelColor(i, strip.Color(0, 0, 0, 255)); // Set white
      } else {                                             // else set rainbow
        int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
        strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
      }
    }

    strip.show(); // Update strip with new contents
    // There's no delay here, it just runs full-tilt until the timer and
    // counter combination below runs out.

    firstPixelHue += 40; // Advance just a little along the color wheel

    if((millis() - lastTime) > whiteSpeed) { // Time to update head/tail?
      if(++head >= strip.numPixels()) {      // Advance head, wrap around
        head = 0;
        if(++loopNum >= loops) return;
      }
      if(++tail >= strip.numPixels()) {      // Advance tail, wrap around
        tail = 0;
      }
      lastTime = millis();                   // Save time of last movement
    }
  }
}

void pulseWhite(uint8_t wait) {
  for(int j=0; j<256; j++) { // Ramp up from 0 to 255
    // Fill entire strip with white at gamma-corrected brightness level 'j':
    strip.fill(strip.Color(0, 0, 0, strip.gamma8(j)));
    strip.show();
    delay(wait);
  }

  for(int j=255; j>=0; j--) { // Ramp down from 255 to 0
    strip.fill(strip.Color(0, 0, 0, strip.gamma8(j)));
    strip.show();
    delay(wait);
  }
}

void rainbowFade2White(int wait, int rainbowLoops, int whiteLoops) {
  int fadeVal=0, fadeMax=100;

  // Hue of first pixel runs 'rainbowLoops' complete loops through the color
  // wheel. Color wheel has a range of 65536 but it's OK if we roll over, so
  // just count from 0 to rainbowLoops*65536, using steps of 256 so we
  // advance around the wheel at a decent clip.
  for(uint32_t firstPixelHue = 0; firstPixelHue < rainbowLoops*65536;
    firstPixelHue += 256) {

    for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...

      // Offset pixel hue by an amount to make one full revolution of the
      // color wheel (range of 65536) along the length of the strip
      // (strip.numPixels() steps):
      uint32_t pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());

      // strip.ColorHSV() can take 1 or 3 arguments: a hue (0 to 65535) or
      // optionally add saturation and value (brightness) (each 0 to 255).
      // Here we're using just the three-argument variant, though the
      // second value (saturation) is a constant 255.
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue, 255,
        255 * fadeVal / fadeMax)));
    }

    strip.show();
    delay(wait);

    if(firstPixelHue < 65536) {                              // First loop,
      if(fadeVal < fadeMax) fadeVal++;                       // fade in
    } else if(firstPixelHue >= ((rainbowLoops-1) * 65536)) { // Last loop,
      if(fadeVal > 0) fadeVal--;                             // fade out
    } else {
      fadeVal = fadeMax; // Interim loop, make sure fade is at max
    }
  }

  for(int k=0; k<whiteLoops; k++) {
    for(int j=0; j<256; j++) { // Ramp up 0 to 255
      // Fill entire strip with white at gamma-corrected brightness level 'j':
      strip.fill(strip.Color(0, 0, 0, strip.gamma8(j)));
      strip.show();
    }
    delay(1000); // Pause 1 second
    for(int j=255; j>=0; j--) { // Ramp down 255 to 0
      strip.fill(strip.Color(0, 0, 0, strip.gamma8(j)));
      strip.show();
    }
  }

  delay(500); // Pause 1/2 second
}