Making Uncanny Eyes

Spooky eyes blink, move and even dilate their pupils.

My middle son and I have a tradition of incorporating electronics projects into our Halloween costumes. This year we saw the tutorial for Uncanny Eyes on Adafruit, written by Phillip Burgess, and instantly decided that we had to make them. The project uses two TFT or OLED screens to create realistic moving and blinking eyes controlled by a Teensy 3.1. This post documents our build process and how we’ve each decided to use the eyes differently in our Halloween costumes. It will make more sense if you’ve read the tutorial on Adafruit, however, you should still be able to follow along even if you haven’t.

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3D Printed No-Carve Pumpkin Decorations for Halloween

3D printed goggles make the minion.
3D printed goggles make the minion.

I love Halloween for its spooky and amusing decorations and am always amazed by the creativity people put into making jack-o-lanterns.  However, it’s frustrating to put hours of creative work into carving a pumpkin, just to have it rot after only a few days.  The simplest solution is no-carve pumpkin decorating.  You can find articles on painted and embellished pumpkins online, however, I haven’t seen any that explore the possibilities that a 3D printer adds.  So, I thought I’d bring a little high-tech to my arts-and-crafts projects.

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“Life” on a SmartMatrix Board

SmartMatrix Game of Life
Custom controller + SmartMatrix board + Teensy 3.1 with SmartMatrix shield = Conway’s Game of Life

The SmartMatrix board is a 32×32 RGB pixel RGB display (other sizes are available), and it makes an eye-catching display.  There is an existing code library to run it from a Teensy 3.1 with a SmartMatrix Shield. The hardware setup and code library are documented at the pixelmatrix website.  The library has all kinds of cool looking built-in effects, like text scrolling and geometric shapes.

The easiest way to program the Teensy is to add the TeensyDuino extension to the Arduino IDE.  Once the extension is setup, the code can be written in the IDE, and it is loaded onto the Teensy board just like an Arduino.  The only noticeable difference is that the code does not automatically load if the Teensy is running a program.  In that case, you have to press the Teensy’s “reset” button to complete the loading of new code.

Any project on the SmartMatrix board had to look good at a low pixel resolution.  Jason Coon’s implementation of Conway’s Game of Life seemed like an interesting application to run.  

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TinyScreen Case with Buttons

3D Printed necklace case with buttons for TinyScreen
3D Printed necklace case with buttons for TinyScreen

I just updated the TinyScreen case I’d 3D printed for my new TinyScreen and TinyDuino.  The new version of the case has protruding buttons to help access the two very small buttons built into each side of the TinyScreen.  I also wrote a new Arduino sketch to demonstrate the button functionality.  The sketch displays a 3d rotating wireframe shape, which changes when the buttons are pushed.

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New IMU Library for Arduino- RTIMULib

Obtaining orientation angles can be a challenge! RTIMULib may make things easier.
Obtaining orientation angles can be a challenge. RTIMULib may make things easier.

My blog traffic shows that a lot of the visitors are looking for information on IMUs (Inertial Measurement Units) like the MPU-6050.  Understanding how to use IMUs and access the data they provide can be daunting.  However, I just came across a new Arduino library for getting IMU data that looks like it will make things simpler.  Written by a company named Richards-Tech, the library is called RTIMULib, and can be found at

What’s incredibly awesome, and more or less unique about this library is that it comes with well-documented sample programs.

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TinyScreen and TinyDuino

TinyScreen displays the Mandelbrot set.
TinyScreen displays the Mandelbrot set.

A few months ago, I signed up for a Kickstarter for TinyScreen – a minuscule 96×64 pixel screen run by a similarly diminutive TinyDuino, an Arduino clone that is smaller than a quarter.  My parts arrived yesterday, and I jumped right into playing with them.

I had ordered the video game package which came with a TinyDuino, a TinyScreen, a TinyShield Joystick, a TinyShield USB (for connecting to the computer with a micro USB cable), and a 140 mAh LiPo battery that plugs directly into the TinyDuino.

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Making MeArm

Fully built MeArm
Fully built MeArm with custom controller.

MeArm is an open-source robotic arm kit by Benjamin Gray and Jack Howard.  They published design files for their robot on Thingiverse and a set of instructions on Instructables.  You can 3D print or lasercut the parts, or you can order them as a kit which includes all servos and screws from Adafruit.  If you create the parts yourself, you’ll need to purchase four 9g servos and assorted lenghts of M3 screws to complete the assembly.

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YAWP – Yet Another Wall Plotter

 The Inspiration:

I’ve been very slow to create posts these last few months.  I like to think it’s not due to laziness, but just that I’ve been so busy playing with other projects.  I’m pushing myself to write up the more interesting ones.  These days I’ve been obsessed with machines that draw.  The biggest of these projects has been my wall plotter, nicknamed YAWP (Yet Another Wall Plotter).

A wall plotter (also known as V-plotter or polargraph) works by moving a pen around a vertical (or slightly angled) drawing surface by means of two motors attached to string or a timing belt.  Although wall plotters are really just very slow, low resolution printers, the potentially unlimited scalability and numerous variations in the output make them compelling to watch.  Because of their simple design and because it’s fun to watch a machine drawing with a pen, they are far more engaging than a typical desktop printer.

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Building PlotClock

I found a YouTube video of a clock that can draw the time with an erasable pen, then wipe it away before restarting the cycle:

There is something very human and endearing about the motion of the arms as they perform their task of drawing and erasing over and over and over again.  After locating the plans and instructions by joo at Thingiverse, I absolutely had to make one.

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Halloween Photoresistor Circuit

Spooky skeleton’s eyes glow when it gets dark out.

Here is a simple project we made for Halloween.  We used a photoresistor and a couple of LEDs to make a spooky skeleton with eyes that light up when it gets dark out.

The Parts:

  • Small rubber skeleton (Party City)
  • Tiny breadboard (I cut a larger breadboard into pieces)
  • Resistors (68 Ω and 82 KΩ or similar)
  • 2N2222 Transistor
  • Photoresistor (eBay)
  • Two red LEDs
  • One double “AA”  (or “AAA”) battery box – as long as the output is 3V
  • Small piece of insulated wire

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