This project starts when you find the perfect hoodie or coat to light up. Find your style and use something that you'll want to wear even during the daytime.
Now it's time to do some sketches. My favorite way to do this is to print out a photo of the hoodie and draw on it with a sharpie. Here are some things you'll want to plan:
Microcontroller
What microcontroller should you use? There are so many pros and cons to every controller out there. I'm using the Metro Mini because:
- Lots of memory means I can upload lots of patterns
- It has 8+ available digital I/O holes in a row and I need that for my 7 buttons
- It's fast, so, better able to handle interrupts to the code from the buttons
If you're planning to add bluetooth or wifi control, look for a board that has that built in (check out the Feather line).
Think about where the microcontroller will be attached. You'll want it someplace that won't get too sweaty if you're dancing (so, maybe avoid armpits, or your hoodie will short out as soon as the fun starts) but close enough to all your LEDs to avoid super long wire runs.
LED Style & Number
How many LEDs do you want to add? Many microcontrollers have limits to how many LEDs they can drive from one pin. Do some research -- although if you keep the LEDs to less than 100-125 you'll be fine with just about any microcontroller.
Remember, more lights will translate to a shorter battery life, so find the smallest number you can be happy with and go from there.
The 144/m neopixel strips make for a buttery smooth animation, but don't cover a lot of area. The 30/m ones look a little spotty, so for my project, the 60/m seem to be just right.
For the back of my hoodie I wanted a starry-night style random scattering of LEDs, so I used individual neopixels. I get a large area lit without so much power draw overhead.
This technique is a bit more work to install. But it's worth it.
Controls Placement
Where will the on/off switch go? Put it someplace you can reach it easily, but where it won't get switched off accidentally if someone hugs you or bumps into you on the dance floor.
If you're using tactile switch buttons, how many do you want to use, and where will you place them?
Battery & Power
Will this hoodie be worn by a kid? If so, a AAA battery pack is the safest and simplest option.
LiPoly batteries are smaller, lighter, and last longer but they do have their dangers, so know about them before you strap one to your body.
Where will the battery live? Pockets are often great for holding batteries, but if your hoodie doesn't have pockets, or if it's form fitting, find a place where the battery will be safe and unobtrusive.
Failing Gracefully
LED strands and wires are delicate, finnicky creatures. Even with all the strain relief and hot glue in the world, your hoodie is likely to break at some point during its lifetime, probably (if you're like me) right before your big stage debut.
One trouble with Neopixels is that when a strand breaks, a pixel goes bad, or a wire gets pulled out, every pixel "downstream" of the break goes dark.
There are a few things you can do to help minimize the number of dark pixels if something goes wrong.
- Connect power and ground to both the "in" and the "out" end of your strip. That way if one power wire breaks, you're still getting power to your pixels.
- Split the pixels into multiple data paths. My design mirrors the left side and the right side, so if one side loses power or data, at least the other side stays on.
- Place high-stress pixels at the tail end of the design. If a pixel is in a bendy place like an elbow, or someplace where it's going to get sat upon, make it the last pixel in line so that when it breaks, it won't ruin the fun for every other pixel.
