Team Kawaii Tech:

•

Abraham Contreras

Published October 17, 2019

Nyan Earrings

Yet another Nyan Cat board with ATtiny85. This time using rechargeable battery and WS2812. <3

BeginnerWork in progress1 hour1,588

Things used in this project

Hardware components

Microchip ATtiny85

ws2812b 3535

JLCPCB Customized PCB

0.1uF 0805 cap

slide switch smd

jst-ph 2pin

Software apps and online services

Arduino IDE

Microchip Studio

Hand tools and fabrication machines

ATMEL ICE programmer

Soldering iron (generic)

Story

The Nyan earrings were inspired by Nyan Cat the pop tart cat flying across the universe with a rainbow on its tail?

Refer to other Nyan Cat earring projects Nyan Board and Nyancat Earrings also using ATtiny85. <3

This board is also using ATtiny85 including 7 small WS2812B 3535 addressable LEDs and it is powered by a rechargeable battery.

Again, we are using inkscape, the svg2Shenzhen extension and KiCAD.

The board size is limited by the battery size which is around 2.5mmx2.5mm. Since I wanted earrings I decided to make the rainbow shorter because I didn't want it to be too big, in the end the size of the board is 56.6mmx29.5mm.

1 / 2 • KiCAD render of nyancat board

Preliminary version of bottom view.

The original concept was placing 3 WS2812B 5050 package but instead I got the WS2812 3535 package. I don't care much about power consumption right now but I will be using a rechargeable battery.

On PCB WS2812 5050 package vs WS2812B 3535 package

I left a pad to place a pin because I had some friends who wanted a pin instead of earrings.

1 / 2 • Layout screenshot everything is placed on bottom. Big footprint is for pin placement

Just drilled a hole for the earring hooks.

Earring hooks, disregard the hanging battery will explain later

I found out I didn't mirror the pads when I was creating the footprint of the WS2812b mini.So it is not possible to reverse mount them, this is the assembly as you can see the WS2812b are placed on bottom but not reverse mount.

LEDs facing up

But Abraham reworked one board because we just had to know how it would look with the WS2812b reverse mounted. In this video on the right you can see the reworked board with the WS2812b reverse mount on bottom. On the left, the LEDs are facing up, but we added hot glue to diffuse light. This is only 10 out of 255 brightness value.

Hot glue seems to do the trick diffusing light, but I don't really like how it looks.

Hot glue to diffuse light

The board has an ISP footprint so is easy to reprogram soldering a header and using the Atmel ICE programmer, in order to place the battery we need to remove the header that's why you see all pics with the battery hanging. We created an Arduino sketch based on Adafruit's rainbow chaser. And set the brightness at 10 (0-255 possible values).

1 / 3 • Modified rainbow chaser code

The header was removed, and the battery was placed with double side tape AND it tilts :( the hot glue makes it heavier.

Tilted Nyan Cat board

I have been playing with the code and different brightness, this photo has 255 level.

Super bright Nyan Cat board

I am still figuring out how much the battery will last I think 128 brightness value is just fine, will solder another board with no hot glue to check if is still tilted.

As for Gerber files I will update I think I will place the LEDs on top, or maybe fix the symbol so I can reverse mount them, what do you think looks better on the previous video? Please post your comments :)

Nyan nyan nyan nyan nyan nyan nyan nyan nyan nyan nyan

We showcased these during the Jalisco Maker Faire.

Photo by Sabas.uf2

Brightness level 128 (out of 255). Super bright! I am unsure of the battery capacity, but the earrings last around an hour at 128 brightness level :(

Nyan it !

Code

Arduino sketch

#include <Adafruit_NeoPixel.h>
//#include <avr/sleep.h>    // Sleep Modes

#define PIN 3
#define NUM_PXLS 7
#define BRIGHTS 128
// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino 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(NUM_PXLS, PIN, NEO_GRB + NEO_KHZ800);

// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel.  Avoid connecting
// on a live circuit...if you must, connect GND first.


// Change these to set speed (lower is faster)

#define ROTATION_RATE  100
 
// Change these to be whatever color you want
// Use color picker to come up with hex values
#define FLASH_COLOR   0xFF0000
#define SPIN_COLOR    0xFF0000
#define CYLON_COLOR   0xFF0000

int colorIndex;
int startIndex;

// Define 10 colors here.
// Must be 10 entries.
// Use 0x000000 if you want a blank space.
uint32_t RAINBOW_COLORS[7] = {
  strip.Color(255, 0, 0),  //red
  strip.Color(255, 255, 10),  //yellowish
  strip.Color(0, 255, 0),  //green
  strip.Color(0, 30, 255), //blue
  strip.Color(128, 0, 255),  //purple
  strip.Color(0, 0, 0),  
  strip.Color(0, 0, 0)
};


void setup() {
  ADCSRA &= ~(1<<ADEN); //Disable ADC, saves ~230uA
  strip.setBrightness(BRIGHTS); 
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
  startIndex=0;
}

void loop() { 
    rainbowChase();
  }

void rainbowChase()
{
  strip.clear();
  strip.show();
  colorIndex = startIndex;
  for (int p=0; p<NUM_PXLS; p++)
  {
    strip.setPixelColor(p, RAINBOW_COLORS[colorIndex]);
    //strip.setPixelColor(p, (0,   0, 127));
    strip.show();
    colorIndex++;
    if (colorIndex>NUM_PXLS)
       colorIndex = 0;
  }
  startIndex++;
  if(startIndex>NUM_PXLS)
      startIndex = 0;
  delay(ROTATION_RATE);  
  }