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Getting rid of the tree was NOT an option. I had to fix it.<\/p>\n\n\n\n
I\u2019m going to tell you what I did, as an adventure story, not a tutorial. There\u2019s a lot I did over the past two nights that was guesswork, and\u2026 probably not the best way to do it. (If you don\u2019t want the gory details of the project, feel free to scroll down to the end.)<\/p>\n\n\n\n
I started by hopping on Adafruit.com<\/a> and perusing their Neopixel options. <\/p>\n\n\n\n Neopixels are individually addressable programable LEDs. Which means that if you have a Neopixel strip with 30 LEDs, you can write a program to set of the color and brightness of each LED separately. You have complete control!<\/p>\n\n\n\n I read a lot of product pages, and took some measurements of the fiber-optic base of the tree (where all the fibers came together.)<\/p>\n\n\n\n Adafruit has a whole Neopixel guide, and there are lots of sample projects. However, none of those were \u201cfix your twenty-year-old Christmas tree\u201d and, a lot of the project write ups had assumed knowledge that I, um, didn\u2019t have.<\/p>\n\n\n\n (Knitters, it was the equivalent of the single-line instruction \u201cturn the heel\u201d in old sock patterns.)<\/p>\n\n\n\n So I took my best guess and bought some stuff:<\/p>\n\n\n\n On hand I already had:<\/p>\n\n\n\n Here\u2019s my workbench<\/p>\n\n\n\n The white box on the left held the supplies for this project. The box on the right is for a different project.<\/p>\n\n\n\n My first challenge was figuring out how to connect the Neopixel shield to the Arduino Uno. The shield came with two types of headers, stacking and plain. <\/p>\n\n\n\n I wasn\u2019t sure which to use, and was even more confused about what connecting the headers would do. Neopixels really only care about three connections: 5V power, ground, and pin 6 on the controller. The shield headers would connect the Neopixel shield to 32 pins on the Arduino. What the heck would that even do?<\/p>\n\n\n\n I toyed around with putting all the headers on, none of the headers, some of the headers. There was no place I found that said \u201cdear reader, here\u2019s all about headers when attaching a shield to an Arduino\u201d. Finally, after looking at pictures of other people\u2019s projects and zooming in, it looked like everyone was using all the headers, making a solid connection.<\/p>\n\n\n\n So I did, too. I chose the plain headers because they stuck up less than the stacking headers and it was important for this project for the LEDs to be as close as possible to the end of the tree where the fiber optic fibers came out.<\/p>\n\n\n\n I was very happy to have my \u201chelping hands\u201d doo-dad when soldering on the headers. I had one hand hold the header and the other the shield.<\/p>\n\n\n\n NEVER solder on headers this way. I learned the hard way that this is a recipe for soldering on your headers crooked, and then they won\u2019t fit into the Arduino Uno (unless you get\u2026 creative with some needle-nose pliers.)<\/p>\n\n\n\n Next time, I\u2019ll try setting the headers on or into a cardboard box and lay the shield on top, letting gravity hold it in place while I solder. I think that might help the headers come out straight. (If you have any killer header-soldering tips, please tell me them.)<\/p>\n\n\n\n Helping hands not so helpful, actually. \ud83d\ude41<\/p>\n\n\n\n In addition to the plain headers, Adafruit included a terminal block for the Neopixel shield, so you can power the Neopixels with a bigger power supply than is provided by the Arduino. Because I wanted bright lights for my tree. I installed it. It\u2019s the bit with the two tiny screws on the bottom of the board.<\/p>\n\n\n\n There was a bad moment where I couldn\u2019t find a screwdriver that would fit those screws. Fortunately a glasses repair kit had the right size.<\/p>\n\n\n\n The cord coming off of the terminal block is half of the 2-pin JST SM plug. This isn\u2019t essential to the project, but does make it easy to connect and disconnect the shield from the power cord. I was very happy I had added it later, as it gave me more slack when I went to install things in the tree.<\/p>\n\n\n\n This is an aside. These are the best wire strippers ever. I highly recommend them. I bought them for working on el-wire and have never regretted it. They\u2019re so easy and accurate!<\/p>\n\n\n\n The other thing I dithered over was the instruction \u201ccut the center of the solder jumper to the right of the terminal block\u201d. This was something Adafruit said to do in order to power the Neopixel shield separately from the Arduino.<\/p>\n\n\n\n Um, what the heck does the solder jumper look like? <\/p>\n\n\n\n This was another place where everyone seemed to already know this so well, that they didn\u2019t feel the need to explain. Looking closely at the shield I had two candidates of what to cut:<\/p>\n\n\n\n I mean, I was guessing they meant cut the line between the two gold pads\u2014maybe? Of course there was the black thing directly beside the terminal. Maybe they meant that instead?<\/p>\n\n\n\n It was tense. I didn\u2019t buy duplicates of anything. Cutting the wrong one would mean no lights on Christmas Eve. \ud83d\ude41<\/p>\n\n\n\n I Googled, I search on YouTube. I squinted at tiny project pictures that I\u2019d zoomed up to maximum. And it seemed like the gold pads were the thing.<\/p>\n\n\n\n So I took an Exacto knife out and cut the link.<\/p>\n\n\n\n And then, how do I connect pin 6 to the Arduino? I just guessed that maybe connecting the shield headers to the Arduino would do that automatically? Because that\u2019s how I\u2019d design it.<\/p>\n\n\n\n (There was a lot of guessing going on at that point.)<\/p>\n\n\n\n This is what the shield looked like after I\u2019d soldered on the headers, cut the jumper, and attached the power adapter to the terminal.<\/p>\n\n\n\n And then, the moment of truth. I finagled the wonky headers and put the shield onto the Arduino, connected the shield\u2019s terminal to the 5V power supply, attached the USB cable to the computer, opened the Arduino IDE, and uploaded some code. <\/p>\n\n\n\n Many hours in, many guesses\u2026 the moment of truth\u2026<\/p>\n\n\n\n This was a very happy moment for me. All the LEDs lit! Nothing blew up!<\/p>\n\n\n\n The next bit was to write the software that would animate the tree lights. I was trying to replicate this: a light that shines through an spinning plastic disk that has been painted different translucent colors.<\/p>\n\n\n\n What I soon realized was that animating analog spinning on a 5×8 grid was a non-trivial coding problem. This was around 3:30am.<\/p>\n\n\n\n So I started plinking at it.<\/p>\n\n\n\n I mapped out the grid into blocks to simplify things, and recreate the size of blocks the original tree had. (I crossed off the pixels on the sides because they didn\u2019t fit the round base of the tree.)<\/p>\n\n\n\n I could change the color of the blocks, but that would have created a strobe effect on the tree, and I wanted the smooth color transitions of the original.<\/p>\n\n\n\n After some pondering, I realized that what I needed was a fade transition from one color to another. I couldn\u2019t find a fade library for Neopixels, so I wrote some fade functions on the fly. (Not bad for someone who hasn\u2019t coded C in at least five years.) <\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a><\/figure>\n\n\n\n