Jack-o'-LED·trix

What happens when a jack-o'-lan·tern gets into a fight with a bunch of LEDs? A Jack-o'-LED·trix!

Ah! Aren't you glad this isn't an instructable about being funny?! Or is it?!

I wanted to put together a pumpkin matrix for Halloween that would give me the opportunity to incorporate some fun sensors and use my bluefruit board. My initial goal for this project was to have a few animations and scrolling text available via the Adafruit Bluefruit IOS app but I ran into a few issues.

First the bootloader on my Adafruit Feather 32u4 Bluefruit kept having issues and I wasn't able to consistently upload a sketch to test things. Though I followed the instructions on the Adafruit site, I couldn't get it working in time and had to come up with another plan.

Second, once I started testing some text examples on my matrix, it looked horrible! With the pixels so far apart, it letters wouldn't be legible unless someone was pretty far away. In addition, many of the text examples I tried were more than 6 pixels high, so a message would likely get lost in one way or another.

Even though I wasn't fully successful in achieving my goals, but I'm still happy with how it turned out. More importantly, I'd love to see what this inspires for you!

Pumpkin or Funkin - I found a large 12" Funkin on sale at a local craft store

12mm stranded LEDs - I used an inexpensive set of 50 WS2811 pixels from Amazon

Knife or pumpkin carving tools

Drill + bits (1/4", 7/16" & possibly 1/2")

Solid core wire or jumper cables

Arduino - I planned on using a Adafruit Feather 32u4 Bluefruit but ended up with using my Arduino Uno

Power Source/Connection - I used a USB cable + USB power bank

Cut a large hole into the top of the pumpkin as an access point. If you're feeling smart, you might want to throw a nice notch in there.

I mapped out the location of my holes with pencil. I picked a location as the center spot to chart out holes that were approximately 1.5" apart. Since the surface is spherical, the holes on the top and bottom row will be closer together than 1.5" apart. You can map things out more strategically on a globe, but I found that the inconsistent surface didn't require perfection of placement.

After marking the holes, drill pilot holes with a 1/4" bit and then larger holes with the 7/16" bit. A 1/2" bit may work better, so it's good to have one around as well. Test the holes with a pixel and go with a larger bit if needed.

For an even number of rows, begin in the bottom left hand corner. For an odd number of rows, begin in the bottom right hand corner. Press the pixels in to the holes in a zig-zag pattern until you reach the top left hand corner.

Due to the issues I had with my bluefruit board, I ended up loading the xymatrix example code from the fastLED library onto my Arduino Uno.

Once I confirmed it was working, I tucked the Uno, a USB cable, and my power source into the pumpkin.

If you've used a real pumpkin, toss the board and battery into a ziploc bag before putting it inside.