![]() ![]() The downside to this method is that the diode dissipates quite a bit of power.The Neopixels still work fine at 4V, and the difference in logic levels is much smaller. ![]() The diode "fixes" this by dropping Vin at the Neopixels by about 1V. On other power supplies, though, the difference between logic high for the Neopixels and logic high for the Imp is too great, so the Neopixels don't respond. ![]() On some power supplies, the Neopixels don't mind this so much and they listen and do the Right Thing.As such, when the imp sends signals to the Neopixels, logic high is 3.3V, not 5V. The breakout board includes a power supply that provides the Imp with the necessary 3.3V rail. I put a diode between VIN on the Imp breakout and PWR_IN on the Neopixel ring - strange! This is a bit of a hack, and it has to do with the fact that the Imp doesn't run at 5V.If you're planning to power your board some other way, keep this requirement in mind. When the imp is running from the 5V on the USB connector, the "Vin" pad on the Imp breakout passes 5V through. We're going to provide this by powering our gadget from a USB connector (VBUS is 5V). The Neopixels are intended to be used with a 5V power rail.If you just want to build it as drawn and not worry about the details, skip the bullet points: A couple notes on the electrical design here. Check out the circuit diagram above to see how this goes together. Basically very serious double-sided tape. I used a roll meant for mounting glass in shower doors, which is clear and very, very sticky. Ruler (A T-square is super helpful, if you can get one).A 1/8" hole is the right size for the 4-40 hardware we've picked out. Drilling through acrylic with a wood drillbit is a nightmare you'll almost certainly break the acrylic. You only need this for one step (connecting the Imp), so you can borrow one from a friend if you don't have one of your own. You'll program the Imp from your web browser. This is the full wish list you can make do without having every last one: (Or more accurately, you've already spent your $10 and don't have to spend it again) If you have spare machine screws lying around, you save $10. I picked up a plastic picture hanger while I was at TAP for $0.45.Īpproximate parts cost: $77.00.Home Depot and similar may also be able to help out with this piece. I got mine from Tap Plastics in Mountain View they gave me 9 of them for $8.00 (call it $1.00 a square). Two 3"x3" squares of 1/8" Smoked Acrylic.This will set you back a whopping $0.15 or so. Radioshack or Fry's keep these around, too. You'll want one that can handle 1 A or more. We use this just to do a little hack to make the imp play nice with the Neopixels. You can use bigger or smaller, but I'll assume for the sake of mechanical design that you're using the 24-pixel variety, too. We'll be programming the imp entirely over WiFi. You'll need a Mini USB Cable, too - it's only for power.An Electric Imp card and an Electric Imp Breakout - About $37.50 total.The weather indicator is really handy - let's build one! I'm really looking forward to seeing what else it can do. By the end of the day that I built this project, it could already also be used to track packages or tell time. My theory was that the geeks I work with would be unable to resist writing other applications for the shiny new toy, and it turned out I was right. It turns out to be a snap to build, and not expensive! This seemed as good a place as any to start, so I connected an Adafruit Neopixel Ring to the internet with Electric Imp, cooked up some animations, and set it up to grab the forecast from Weather Underground. I've had a theory for a little while that just a dozen (or two) pixels and an internet connection are all you need for a seriously vast number or applications. When it comes time to make the trek down the street to get some lunch, I'm never quite sure what I'm going to find in the great out-of-doors. In my case, my coworker at the desk across from mine has the window seat. We can't all have the desk next to the window. ![]()
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