One of the greatest things about the Maker scene is that there's just so much of it—it encompasses everything from rocketry to hydroponics. And as a maker, just getting started can be the hardest part: deciding what to work on next, or if you're new to the scene, what to work on first. So I'm starting up a new series of articles that I hope will help you get your bearings on what's possible. But I'm going to refrain from calling out specific projects to work on; not only would my list probably be unhelpful (there's only so many ways to write "build a fighting robot"), it sort of defeats the point of the whole endeavor, which is to express yourself through creating something suitable to your own abilities and interests. Instead, I'm going to look at some cool components that could be a major part of lots of different projects. Hopefully you'll be inspired.
Today, we're going to explore the uses of LED strip lighting—a great, simple component that can add a lot of visual impact to any project. LED's provide bright, colorful and (in some cases) customizable light, and by buying them in strip form you save yourself a lot of time and effort at the soldering bench.
In order to examine the world of flexible lighting, I chose to put together a quick project of my own. I have some problems with the lighting in my living room—particularly when watching movies. With all the overhead lights and lamps turned off, the room gets pitch black, aside from the screen. With any room lights on, glare appears on the TV. So for a simple lighting project, I decided to mount a strip of lights to the back of the screen, to provide a gentle glow for the wall behind it.
Step one was to buy some lights. There are a whole lot of varieties of LED strip lighting on the market right now, but for the most part they fall into three categories, as follows:
Single Color, Non-Addressable: This is your basic "dumb" LED strip lighting. They come in plenty of colors, and are great for providing bright, colorful lighting in fixed location. These are commonly mounted under cabinets or tables to provide a nice recessed glow, or as a source of indirect lighting for home theater setups or display cases. They're relatively inexpensive, and you can buy them in plenty of colors and intensities.
RGB, Non-Addressable: RGB strips are able to display any RGB color, and can change dynamically. They're a good alternative for lighting projects where you want to be able to create different moods. They're more expensive than single-color strips, and require some sort of microcontroller. If you're so inclined, pre-made kits are available which include everything you need.
RGB, Addressable: The most customizable, most controllable, and just generally most awesome LED strips. Addressable LED strips are color-changing, like the previous category, but go a step further and include a tiny chip in between each and every LED, allowing you to control them all individually. They're the most expensive, and to get the most out of one you will definitely need a microcontroller. They can be used for the most sophisticated lighting projects, or can even act as an art object all on their own. Additionally, they're perfect for projects that rely on persistence of vision to create images in the air.
For my project, I decided to go with the RGB addressable strip. "Hold on," you might be saying, "didn't you just say that single color strips were good for home theater installations?" Yes, I did, but it's also important to keep in mind how truly sweet those addressable RGB strips are. I mean, you really should watch the video. I decided on the spot that my TV backlight project is going to have a fiesta mode.
In addition to the lighting itself, I needed a power source. LED strips are powered by direct current sources, and their voltage needs differ from strip to strip—you've got to pay close attention to the spec when you buy it, and make sure you've got a power source that can provide just the right amount. I decided to go with the addressable strip from Adafruit, which is a very reasonable $29.95 per meter, as well as the power supply I would need to run it. There's a chance I could have found better prices on individual components by shopping around more, but because I live in Hawaii shipping prices can be a pain, and it's helpful to get everything from a single retailer.
Finally, there's the issue of control. You're not going to get the LEDs to change color by asking them nicely—you need a microcontroller. There are a number of solutions, but the most widely used is Arduino. So I went ahead and tossed an Arduino Uno R3 and its power supply into the cart.
A few days later I got the parts in the mail, and started the process of building my TV backlight. There's not much to a backlight, of course, but anything involving addressable LEDs takes at least three steps:
First, you have to solder leads to the strip of lights. When you buy LED ribbon, unless you get a whole 5 meter roll at once, you get a piece that's been cut off of a longer quantity, so they tend to come without leads attached. It's pretty simple soldering, you just have to make sure that you're attaching wires to the correct side of the ribbon. Both ends will have a set of four contacts, but on one end the middle two contacts are labeled "DI" and "CI", and on the other end they are "DO" and "CO". You want the side with "I"s—they're short for "In." The connections are a little vulnerable at this point, so I suggest strengthening and insulating them with a little heat shrink tubing or electrical tape.
Second, you connect the LED strip to the Arduino and the power source. This involves connecting the "DI" and "CI" (data in and clock in) wires to two of the digital pins on the Arduino, and the other two to the power supply and the power supply and Arduino's common ground. For a more in-depth guide to wiring an addressable LED strip, check out Adafruit's excellent tutorial.
Finally, you need to use your computer to send a program to the Arduino for it to execute using the LEDs. For this you need the Arduino IDE (which includes the Arduino USB driver), as well as a library that allows you to control the chips on the LED strip. For the particular strip I bought, that library is available here.
I'm not going to go too deeply into how Arduino works or how to use it, because that's a topic I'll cover in a future guide. For now, I'll just mention that you program the Arduino by writing a very simple program in C that defines which LEDs should light up at what time. It's still programming, so be warned if that makes you squeamish, but controlling the LEDs is about as simple as C programming gets, and you could easily learn everything you need for the task in a few hours.
For my project, I added two push buttons to the Arduino, and wrote a simple program where one button cycles through three modes (steady light, slow "throbbing", and fiesta mode) and the second button cycles through several different color options. To mount the backlight to the TV, I bought some standard 3M two-sided mounting tape and applied it to the Arduino and the LED strip. I stuck the whole thing to the back of the TV and voila, pleasant mood lighting for any genre of movie and/or fiesta.