For the past couple of weeks, I've been happily playing with Adafruit's NeoPixels. Sad to relate, I just ran into a slight problem, which may have taken out one of my NeoPixel Rings. Fortunately, there is a solution.
Now, before we plunge headfirst into the fray, I'd like to start by saying that I have the utmost respect for the stuff (products, tutorials, and whatnot) from the folks at Adafruit. Quite apart from anything else, I really like the way the company seems to anticipate things I need. As a simple example, I recently purchased a 5V 10A switching power supply to power my NeoPixels (about which, more below).
As we can see, the output from this power supply is delivered via a 2.1mm male plug. In the past, I would typically have cut this plug off (which I hate doing) and connected the wires directly into my project, but this gets to be a pain when one wishes to move the supply from one project to another. So you can only imagine my surprise and delight to discover that Adafruit also offers a female DC power adapter (a 2.1mm socket with a screw terminal block) as shown below.
I don't know if this is an Adafruit special, or if you can find such devices all over the place. What I do know is that I've never seen one before, but I love the idea. I immediately ordered one, and I will be adding a bunch more to my next order (which I will be placing sooner rather than later, I have no doubt).
But that's not what I wanted to talk to you about. A couple of weeks ago, I decided to make an infinity mirror. This is when I first became aware of Adafruit's NeoPixels, which are an incredibly cool idea. Each NeoPixel is presented in a small (3/16" square) package that includes red, green, and blue LEDs along with pulse-width modulated controllers. Furthermore, each NeoPixel has only four external terminals: 5V, 0V (ground), data-in, and data-out, which allows you to daisy chain a bunch of them together. For example, consider the Adafruit NeoPixel Digital RGB LED strip, which contains 60 NeoPixels per meter. You actually purchase this by the meter.
Using the Arduino library that you download from the Adafruit website, you can control the color and brightness of each pixel individually -- and the amazing thing is that all this requires only a single digital output pin on your Arduino microcontroller.
While I was playing with such a strip in the context of my infinity mirror, I thought, "Just a minute. These NeoPixels would be ideal for my pedagogical and phantasmagorical inamorata prognostication engine. I've had this project on the back burner for a couple of years. The problem is that I need to be able to monitor a lot of switches and knobs and control a lot of LEDs and analog meters. Every time I've turned my attention to this in the past, things have quickly grown too cumbersome, and my attention has drifted away again. But it struck me that I could use an Arduino to control all the LEDs using a single output pin. Also, I can use the Arduino's PWM outputs to control my analog meters and its analog inputs to monitor my rotary potentiometers.
The image below shows my first-pass layout for the control panel. Things have evolved a little since I took this picture, but the overall feel is the same.
Currently, I think we are looking at using 116 LEDs. In the case of standalone LEDs, I might simply cut them off a NeoPixel strip like the one shown above. Alternatively, I might be tempted to use the individually presented Flora NeoPixels shown below.
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