NeoPXL8 FeatherWing for Feather M0 - 8
x DMA NeoPixels!
PRODUCT ID: 3249
Since we first started carrying NeoPixels back in 2012, the chainable RGB LEDs
have taken over the world. And a big part of that success is due to the simplicity
surprise they're
everywhere
, blinking away in art exhibits, maker faire demos, DJ
booths, decorations and costumes.
of their wiring - just one data wire, no matter how many pixels you've got. So no
But, at some point, every NeoPixel'er bumps into the constraints of that single-
data-wire: the timing is very picky and often time your code has to stop
completely so that it can burst out the data without any interruptions. This
requirement makes it tough to create fast-update lighting effects, and limits the
number of pixels you can drive before other hardware peripherals get attention.
Resident pixel-pro Paint Your Dragon (who coined the name NeoPixel dont-cha-
know!) took on this challenge and has succeeded gloriously. By carefully
examining the ATSAMD21 datasheet he noticed you could use the Timer 0 in
'waveform' mode, and create 8 unique waveforms over DMA that would handle
all the pixel-pushing for you.
Thus is born the NeoPXL8 Arduino library and NeoPXL8 Featherwing! The library
runs on our Feather M0's (the Basic Proto, Adalogger, Bluefruit, Express, and
DMA output each one can be 250 pixels long for a total of 8 x 250 = 2000
pixels. That leaves you some RAM for your code to run in as well - the
M0 chip.
To make connection easy, this Featherwing does the level-shifting and pin
arrangements for you. All 8 strands have a level shifter that converts the 3.3V
logic level to 5V logic, there's a little switch-cap converter that generates the
reduces ringing on long wiring runs.
You get two options for connecting NeoPixels:
others) and handles all the NeoPixeling for you, up to 8 strands of concurrent
theoretical max is 340 pixels per strand but you'd be using all the RAM on the
clean 5V power supply for you. Then a 100 ohm resistor in line after the buffer
2 x 8 Header with ground and 5V-logic signal, in pairs
pair. This matches the same wiring as the OctWS2811
2 x RJ-45 'Ethernet' Jacks, with ground and 5V-logic signal per twisted
To keep the 'Wing compact we let you choose which wiring you'd like to go with,
just solder in the connectors you prefer. Then you'll also need to provide power
through the Wing - the PCB copper would be too limiting. We recommend
together and powering them from their own chunky 5V supply.
to the NeoPixels. Since you'll need many Amps of current, we don't manage that
using terminal blocks or bus bars to connect all the ground/5V power wires
Since we are using TCC0 (Timer 0), we are limited in what pins can be used for
NeoPixel output. Here are the options you have:
Output #0 comes from A3
Output #1 comes from A4
Output #2 comes from either Digital #10 or the Serial TX pin (selectable)
Output #3 comes from either Digital #12 or the Serial RX pin (selectable)
Output #4 comes from either SPI MOSI or I2C SDA (selectable)
Output #5 comes from either Digital #5 or the SPI SCK pin (selectable)
Output #6 comes from either Digital #11 or the SPI MISO pin (selectable)
Output #7 comes from Digital #13
As you can see, some of these pins are fixed (A3, A4, #13) and the rest have two
options. If you absolutely cannot spare both options, you can disable that from
the NeoPXL8 DMA output and live with 7 strands only.
While we designed this specifically for use with Feather M0 (SAMD21 based),
you
could
use it with other Feathers, for the level shifting capabilites. You'll just
have to figure out what NeoPixel driver firmware you can use and what pins are
available.
If that all sounds groovy to you, pick up one of these wings and check out the
NeoPXL8 Arduino library examples to get your massive LED project going!
Dimensions (board only, no components): 50.7 x 23 x 2.6mm
Product Weight: 3.6g / 0.1oz
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