Adafruit NeoPixel

Objectives

• hook up a NeoPixel to a micro-controller program the pixel (to do)

See also

• Adafruit Circuit Playground Express
• Adafruit GEMMA
• Adafruit NeoPixel
• MakeCode

• Quality: draft

• Difficulty: beginner

Introduction

In this article we describe the Flora RGB Smart NeoPixel version 2

See also:

• Adafruit Circuit Playground Express
• Adafruit FLORA
• Adafruit GEMMA

The pixel

Main characteristics:

• 12.5mm diameter
• 2.5mm total thickness
• 800 KHz speed protocol
• Chainable design, meaning that you can connect several of these to one pin and chain them
• 5-9VDC power (can run at 3.5V but color will be dimmed), constant current 18.5mA per LED (~55mA max total per pixel)

Hooking up a NeoPixel

According to Hook up alligator clips (retrieved Aug 2019), a NeoPixel must be connected with three wires to a FLORA-type board. Depending on the board, the wiring is bit different. E.g. on a GEMMA, the signal must be wired from A1, but the principle is the same:

• Connect the + cable to a VOUT (Volt Out) pad
• Connect the - cable to a GND (Grounding) pad
• Connect the data cable to Ax an input/output pad

Wiring from a CPX

Wiring with a Circuit Playground Express

Board	NeoPixel	Strip with cables (but verify that)
VOUT (Power output)	+	red
GND (Grounding)	-	black
A1 (or another general Purpose Input Ouput pad)	↑ (arrow pointing towards the inside)	white

Wiring from a Gemma

Wiring with a GEMMA

Board	NeoPixel
VOUT Power output	+
GND Grounding	-
D1 / ~A0 General Purpose Input Ouput	↑ (arrow pointing towards the inside)

Gemma - NexPixel wiring (improvised): Read is power, black is grounding and white is the signal

MakeCode example for the Circuit Playground Express

This does the following:

• On start, a short animation of 5 seconds of the strip
• After that all turned to black (off)
• Pressing Button A -> All Pixels will be blue
• Pressing Button B -> All Pixels will be red
• Pressing A3 (or the attached copper) band: Three loops that will light up with different colors. After that: all set to yellow

Connecting a NeoPixelstrip to a playground Express

To play with this example, simply copy the code below, then paste it into the {} JavaScript code tab at https://makecode.adafruit.com/#editor. You then can switch to the blocks editor. Make sure to start from a fresh project.

// Button A down
input.buttonA.onEvent(ButtonEvent.Down, function () {
    // show blue on all pixels
    strip.setAll(0x0000FF)
})
// Button B down
input.buttonB.onEvent(ButtonEvent.Down, function () {
    // show red on all pixels
    strip.setAll(0xFF0000)
})
// A3 touched (you could add a strip of copper)
input.touchA3.onEvent(ButtonEvent.Down, function () {
    for (let index2 = 0; index2 <= strip.length(); index2++) {
        strip.setPixelColor(index2, 0xff0000)
        pause(100)
    }
    for (let index22 = 0; index22 <= strip.length(); index22++) {
        strip.setPixelColor(index22, 0x00ff00)
        pause(100)
    }
    for (let index3 = 0; index3 <= strip.length(); index3++) {
        strip.setPixelColor(index3, 0x0000ff)
        pause(100)
    }
    for (let index32 = 0; index32 <= strip.length(); index32++) {
        strip.setPixelColor(index32, 0xffff00)
    }
})
let strip: light.NeoPixelStrip = null
// mount an external Neopixel strip on pin A1 with 30
strip = light.createStrip(pins.A1, 30)
// show default animation for 5 seconds
strip.showAnimation(light.rainbowAnimation, 5000)
// Turn it off (make colors black)
for (let index = 0; index <= strip.length(); index++) {
    strip.setPixelColor(index, 0x000000)
}

To celebrate, 3D print the little cup from BlockSCAD with a food safe plastic, then fill it with an invigorating drink.

Programming a strand of pixels

This also works with a single pixel...

• Code with Makecode

Links

Official general documentation (read this)

• Adafruit NeoPixel Überguide

• Sewable NeoPixels
  • Code with Makecode

Tutorials

• Wearable neopixels