The Imp doesn't support this natively, so we use the Imp's SPI bus to emulate it. Neopixels use a special 1-wire protocol to communicate, and timing is critical.You can make one out of a PFET and two 1kΩ resistors! If you want to drive a lot of Neopixels (and use a lot of power), you should solve this problem in your design *properly* - by adding a level translator. 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.
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