Since the beginning of NeoPixels in 2012, RGB LED chains have taken control of the entire world. And much of that success is due to the simplicity of their wiring - a single data wire, no matter how many pixels you have. It is therefore not surprising that they are everywhere, blinking their eyes in art exhibitions, makers demonstrations, DJ booths, decorations and costumes.

But, at a given moment, each NeoPixel'er comes up against the constraints of this unique data thread: the timing is very sharp and often the time your code must stop completely so that it can send the data without any interruption. This requirement makes it difficult to create fast lighting effects and limits the number of pixels you can drive before other hardware devices attract attention.

Resident pixel-pro Paint Your Dragon (who invented the name NeoPixel dont-cha-know !) took up this challenge and succeeded brilliantly. By carefully examining the ATSAMD21 data sheet, he noticed that you could use the Timer 0 in'waveform mode' and create 8 unique waveforms on DMA that would support all pixels for you.

Thus was born the NeoPXL8 Arduino and NeoPXL8 Featherwing library! The library runs on our Feather M0's (Basic Proto, Adalogger, Bluefruit, Express, and others) and manages all NeoPixeling for you, up to 8 simultaneous DMA output strands of 250 pixels each for a total of 8 x 250 = 2000 pixels. This leaves you some RAM to make your code work as well - the theoretical maximum is 340 pixels per strand but you would use all the RAM on the M0 chip.

To make the connection easier, this Featherwing takes care of the level adjustment and pin layout for you. All 8 wires have a level adapter that converts 3.3V logic level to 5V logic, there is a small switch-cap converter that generates 5V clean power for you. Then, a 100 ohms resistor in line after the buffer reduces bounce on long wiring runs.

You have two options to connect NeoPixels :

    2 x 8 connector with ground and 5V logic signal, per pair.
    Connector 2 x RJ-45'Ethernet' Jacks, with ground and 5V logic signal per twisted pair.

This corresponds to the same wiring as OctWS281111.

To keep the featherwing compact, we let you choose the wiring, just solder the connectors you prefer. Then you will also need to supply power to the NeoPixels. As you will need a lot of power, we will not be able to do this with the fether wing - the copper on the PCB would be too restrictive. We recommend using terminal blocks or bus bars to connect all power wires to ground/5V and supply them from their own 5V power supply.

Since we use TCC0 (Timer 0), we are limited in what pins can be used for NeoPixel output. Here are the options available to you:

    Output #0 comes from A3
    Output #1 comes from A4
    Output #2 comes from Digital #10 or Serial TX pin (selectable).
    Output #3 comes from Digital #12 or Serial RX pin (selectable).
    Output #4 comes from SPI MOSI or I2C SDA (selectable).
    Output #5 comes from Digital #5 or SPI SCK pin (selectable).
    Output #6 is either Digital #11 or SPI MISO (selectable).
    Output #7 comes from Digital #13.

As you can see, some of these pins are fixed (A3, A4, #13) and the others have two options. If you can't spare both options at all, you can disable this from the NeoPXL8's DMA output and use only 7 strands.

Although we designed it specifically for Feather M0 (based on SAMD21), you can use it with other Feathers, for level shift capabilities. You will only need to determine which NeoPixel driver firmware you can use and which pins are available.

Documentation : Adafruit_NeoPXL8

Dimensions (board only, no components): 50.7 x 23 x 2.6 mm.
Product weight : 3.6 g / 0.1 oz