Around Halloween, even the most innocent of things seem to turn evil. For example our office mascot, Goat, has started acting weird lately...

This tutorial teaches you how to make your own plush toy with LED eyes that can be controlled by an iPhone. The perfect Halloween scare!

Step 1: Get the Parts

We will be using an Arduino compatible microcontroller called the LightBlue Bean to change the color of the LEDs. It connects to your phone over BLE and comes with an iPhone app called LightBlue that you can use to control it.

This is what you'll need:

One LightBlue Bean

A plush toy of your liking. We used this goat.

Two common cathode RGB LEDs (common anode also works but requires a bit of extra work)

Six 270-330 ohm resistors

A 2xAA battery holder

Two AA batteries

Wire and some heat shrink tubing

Basic sewing gear

Soldering iron

Wire stripper

Step 2: Solder the LEDs

Connect the battery to the BAT pin on the Bean and ground. Then connect the RGB pins to pin 0-5 on the Bean with resistors in between, and the cathode to ground. Insulate with heat shrink tubing.

Step 3: Perform Surgery on Goat

Find a plush animal of your liking. Cut a hole in its abdomen and feel like a horrible human being for doing this to an innocent toy. Then feel even worse when you remove its eyes.

Step 4: Put in the Electronics

Put the LEDs, battery holder and Bean in your toy and adjust the LEDs so that they fit in the eye sockets.

Sew the goat together where you put in the electronics. Also sew a bit around the eyes if the holes are too big for the LEDs. Nobody likes saggy eye sockets. That's just scary in a wrong way.

Step 5: Install SoftPWM Library

To be able to fade the LEDs, we will need to use a SoftPWM library. This lets you use any digital pin on the Bean as analog output. By calling the function SoftPWMSetPercent(PIN_NUMBER, BRIGHTNESS) we can go from 0-100 percent brightness. If you need help installing libraries to Arduino, check out this guide.

Step 6: Upload Code to Bean

Upload this code to your Bean.

Download the iOS application LightBlue, open it and connect to the Bean, click options and choose Sandbox View. Use the sliders and checkboxes to control the LEDs!

The first slider will set how red the LED is, the second green, the third one blue and the last one sets Goat in disco mode. Nothing makes a party like that!