Hi everyone! In this tutorial we are modifying a cool zombie plush toy with LED matrices from Adafruit. Don't worry ...it looks scary, but the zombie is totally harmless! I really love the Plants vs Zombies video games. I bought an official zombie plush toy of the game once. In the last weeks I got really interested in the simple 8x8 matrices made by Adafruit. I came up with the idea of replacing the plush toys eyes with two matrices and implement some funny animations. The toys head seemed big enough to me to contain an Arduino Pro Mini, a 4x AA battery box and all necessary wires. Before I knew it, i already started this awesome project. Sometimes I forgot to take a good picture of the progress. If you have any questions, feel free to ask!

Please note that this tutorial requires sewing, soldering and a few programming skills. It's a challenge!

Step 1: Materials

Before getting all materials you should decide what functions your zombie should feature. My version uses two white and ultra bright matrices from Adafruit. You can get them in many different colours like red or green and two sizes (1.2" or 0.8"). You could also use a little speaker inside to make some noises, a photoconductive cell to measure light intensity and adopt the brightness of the matrices automatically or a little vibration motor. How about a switch to change the color and speed of the matrices animations? It's up to you! If you don't want to use batteries to power your zombie, you could use the Adafruit Trinket as your microcontroller and plug a micro USB in to get power.

For my version as shown in the pictures you need:

Materials:

1 zombie plush toy
2 white 1.2" 8x8 matrices with backpack from Adafruit
1 4xAA Battery Box with on/off switch and batteries (1.5V)
1 Arduino Pro Mini (and a serial port adapter/FTDI to program the Arduino)
1 small zip (fitting the color of the zombies head)
Sewing cotton (fitting the color of the zombies head)
Wires and heat shrink tube

Tools:

Soldering iron and solder
Scissor and needle
Lighter
(Third hand with magnifier)

Step 2: Zombie Preparation

At first remove the eyes of your toy carefully with a sharp scissor (or what you prefer to use). The holes should be a little too small for your matrices (as seen in the picture). Be precise here! The matrices should sit tight in place. Finally cut a little hole on the lower back of your toys head open. This is where we insert the Arduino and the battery box later on. Remove some of the toys stuffing.

Step 3: Soldering Part 1

Now it's time for some soldering. Heat up your soldering iron! Solder the LED Backpacks onto the matrices. Be careful! Follow this tutorial on how to do this correctly. It only takes a few minutes. Afterwards I connected wires to the matrices, that will later be connected to the Arduino. Now solder headers to the Arduino. If you've never done this before, here is a good tutorial.

Hint: I used jumper wires to connect the matrices headers with the Arduino headers to easily reuse these parts in others projects.

Step 4: Soldering Part 2

Let's finish soldering! At first connect minus (-) of both matrices with ground (GND) each on the Arduino. Connect plus (+) with VCC each. Pin 1 (C) of both matrices need to be combined and afterwards connected to pin A4 on the Arduino. Pin 2 (D) of both matrices need to be combined as well and finally connected with pin A5. When combining wires (can be done with GND and VCC as well) be patient and careful. Don't forget to isolate all of your connections with heat shrink as shown in the pictures. Video: How to use heat shrink. Everything needs to be safely isolated.

Overview of connections between the matrices and the Arduino:

+ to VCC
- to GND
D to A5
C to A4

Hint: In the picture showing the Arduino you can see a switch I added later and is not part of this tutorial. I use the switch today to select between a low and a full brightness mode.

Step 5: Coding and Compiling

You can download the complete code from my Github repository. The code is spilt into EyeAnimation.ino, where the action takes place and the anim.h, where the eye expressions are located. Both files are needed for the project. Simply download the complete zip.

It's necessary to install Adafruits Backpack library before uploading the code onto your Arduino. Follow this tutorial in order to download and install the library correctly. Finally upload everything and see if your circuit works fine. Of course you can modify the code in any way you want. Have fun with it and try new animations! It's yours!

Step 6: Sewing and Finalizing

In the last step we are going to sew a zipper to the back of the head to close the hole. With a zipper the battery box and the switch are still accessible. You can tie the battery box on the back of the toy alternatively. So it looks more like a space suited zombie for example. Before starting sewing, get everything inside of the head of your toy (Arduino, wires, batterybox...).

After you've attached the zipper, fill the head with some of the stuffing removed at the beginning of this tutorial. Don't use to much to prevent the wires from being damaged. If the zipper closes correctly and everything is working fine your done! Congratulations!

Progress to my optinal part, if your animated zombie is a gift for someone!

Step 7: Optional: Gift Box

This is just an inspiration if you are going to give away your zombie. I made a little gift box out of cardboard. A perfect way to give your zombie to someone!