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Meggy Jr.: Multicolor LED Matrix Display Kit

By Ari Dubinsky

Description: Meggy Jr RGB Kit
Assembly Time: 2-3 hours
Skill level: Intermediate (soldering required)

Meet Meggy Jr., a handheld platform for developing your own pixel-scale video games. Evil Mad Science's Meggy Jr. has an 8x8 LED matrix display, six comfy buttons, a noise making device, and even 8 extra LEDs for whatever you like. Meggy Jr. can run on batteries or an external power source. Meggy Jr. is fast, programmable, open source and hackable. Meggy Jr. is here to play.

Essential Parts and Tools:

Meggy Jr. LED Matrix Display Meggy Jr RGB Kit
Soldering iron
Wire cutters + Pliers
AAA batteries

Optional Tools:

Resistor lead forming tool
Wire strippers

Recommended Parts for Programming:

USB to TTL converter
USB cable

Step 1 - Inventory Check

Like all electronics projects it's important to do an inventory check. You never know when you'll end up with less than the required pieces, so take the time to look through each bag. Who knows, you might even end up with some useful spares.

Kit inventoryKit inventory

Step 2 - Attaching Resistors and Headers

Let's begin! Pull out that wonderfully color coded manual and carefully look over the first 4 pages. You'll notice an inventory of materials and a tool checklist that is important to consider. Flip to page 5. The first thing I noticed when looking over this manual is how easy it is to read and follow. It is a very clear and understandable guide. Way to go Evil Mad Science! Begin by placing either your resistors or headers in their respective spots. I'm putting these two in the same step because at this stage it's not critical which goes first, transistors or headers. The choice is yours; just make sure to bend your transistors to a 90° angle before soldering.

Attaching Resistors and HeadersAttaching Resistors and Headers

Step 3 - Attaching Chips and Buzzer

In come the driver chips and buzzer. Again, at this point it's not too important to place emphasis on which goes first because there isn't much clutter. As a rule of thumb you generally want to begin with the lowest laying components, in this case our resistors, and end with the largest. Make sure to orient the buzzer correctly as it is polarized and don't be afraid to lay the chips flush with board. Solder securely.

Attaching Chips and BuzzerAttaching Chips and Buzzer

Step 4 - Attaching Crystal and Capacitors

Place and solder the crystal in its spot in either orientation. For the capacitors, begin with the ceramic yellow caps (capacitors) and place them in either orientation. After the ceramic caps, bend the leads of the radial caps to a 90° angle and lay them flush with the board. It may be best to place them on the board so you know which way to bend the leads. The capacitors will have a stripe down one side, usually the side that has a minus (-) sign on it. My board did not indicate which direction to face the negative side, but with the board facing as shown in picture above, the negative leads should face you.

Attaching Crystal and CapacitorsAttaching Crystal and Capacitors

Step 5 - Adding LEDs and Optional In-line Header

Place the diffused LEDs at the top of the board and orient them so that the flat side is facing right as pictured. The next step is optional. Only add the 6-pin dual in-line header if you already have and plan to use an ISP programmer. It is not needed for using the Meggy Jr. or for programming through a USB-TTL cable. If you are really sure that you need it, add it on the back side of the circuit board.

Adding LEDs and Optional In-line HeaderAdding LEDs and Optional In-line Header

Step 6 - Socket Strips and Buttons

Now, the instructions tell you to attach the socket strips to the matrix panel before soldering, but I'm here to advise you that it doesn't really matter. Fitting the sockets onto the matrix will produce the same result as soldering the sockets to the board first. Just make sure to apply firm and even pressure when fixing the panel to the sockets. After the panel is attached, go ahead and solder your buttons and watch where the black nubs are on the underside of each button. Don't forget the reset button!

Socket Strips and ButtonsSocket Strips and Buttons

Step 7 - Nearly Finished - Battery Box, Jumper Header and Button Cap

This part is fairly straightforward. Attach your battery box from the underside and remember to pull the wires up through the strain relief holes first. Attach your header jumper over the left two pins of the 3 pin header. Snap the six button caps onto the large button switches. Install the four clear rubber bumpers to the bottom of the circuit board on flat parts of the board close to the four screw hole locations.

Battery Box, Jumper Header and Button CapBattery Box, Jumper Header and Button Cap

Step 8 - Finishing Touches

Place plexicover on and hand tighten screws only as much as needed. The nylon screws secure the upper and lower shell of the handle set. Insert the screws from the top side. And finally, use the strip of Velcro to attach the battery box to the back side of the circuit board.

Scew all the holes
Placing the velcro strip


The Meggy Jr. comes with its own preprogrammed game but if you wish to play additional games you can program the Meggy Jr. through the Arduino development environment.

Follow the step by step guide and either use the examples that come with the library or games programmed by other Meggy Jr. users, which can be found at http://code.google.com/p/meggy-jr-rgb/downloads/list. For a challenge, you can even program your own games.

Step-by-step guide to playing other users' games:

1. Start-up your Arduino software
2. Tools > Board > Arduino Duemilanove or Nano with ATmega328
3. Tools > Serial Port > Choose the correct port
4. Download game and unzip. You should see a .pde file
5. File > Open > Select .pde file
6. Attach the USB cable to the Meggy Jr. using the USB converter and turn on the device
7. Hit the ‘Verify’ button to compile software
8. Once compiled, hit the ‘Upload’ button
9. You should see your converter blink several times and... now you should have a fully functioning new game to play. Enjoy!

Troubleshooting Guide:

1. Check the soldering job. Make sure the solder from leads don't touch each other.
2. Replace the battery.
3. Match components with the instruction's specifications.
3. Check for damaged components.
4. Make sure polarized components are oriented correctly on the board (e.g. IC, capacitors, and LEDs).

Need more help?
Your first stop should be the Evil Mad Scientist Laboratories forums: http://forum.evilmadscientist.com/ Additional documentation and resource links are posted at: http://wiki.evilmadscience.com/Meggy_Jr_RGB
This project was assembled by Ari Dubinsky. Ari currently attends Cal Poly San Luis Obispo in pursuit of a degree in Electrical Engineering. His interests include shredding on the guitar, electronics, and music production.