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NeoPixels with MakeCode

2017-10-05 | By Adafruit Industries

License: See Original Project

Courtesy of Adafruit

Guide by Peli de Halleux

Overview

The Circuit Playground Express is equipped with 10 NeoPixel LEDs that can be controlled with code to create tons of cool visual effects. In this guide, you will learn the various ways to use the Microsoft MakeCode editor to use those LEDs. The guide also covers how to use additional NeoPixel strips.

Make sure to read the MakeCode primer if you are not familiar with MakeCode and check out the Adafruit NeoPixel Uberguide for more details on those amazing LEDs.

Show Ring

The show ring block lets you choose the colors of the 10 LEDs. You can find it find under the light category.

You use multiple show ring blocks to create basic animations. The example below is a blinking siren animation that repeats in a forever loop.

The example is a blinking siren animation

Copy Code 
loops.forever(function () {
    light.showRing(
    `black black black black black red red black red red`
    )
    light.showRing(
    `black blue blue blue black black black black black black`
    )
}

Required Parts:

Built-in Animations

The show animation block provides a set of built-in animations. You can find it find under the light category.

The block will run the animation for the requested time, then continue the program. If another animation is already running, it will be queued and wait for its turn to run.

The example below shows the Rainbow animation running in a forever loop. The runtime maintains an animation queue and waits until the animation is fully executed before continuing to run.

The example shows the Rainbow animation

Copy Code 
loops.forever(function () {
    light.pixels.showAnimation(light.animation(LightAnimation.Rainbow), 2000)
}

Responsive Animations

When you need to run an animation to respond to an event, you'd typically want it to run immediately. To avoid waiting for other animations to finish, make sure to add the stop all animations block. This block stops the current animation and clears the animation queue.

In the example below, we want to run the Sparkle animation as soon as a shake event is detected. To do so, we add a stop all animations block before the show animation block.

Sparkle animation as soon as a shake event is detected

Copy Code 
loops.forever(function () {
    light.pixels.showAnimation(light.animation(LightAnimation.Rainbow), 2000)
})
input.onGesture(Gesture.Shake, function () {
    light.pixels.stopAllAnimations()
    light.pixels.showAnimation(light.animation(LightAnimation.Sparkle), 2000)
})

Frame by Frame Animations

In some case, you might want to be able to control frame by frame how the animation runs. This is also possible but requires a bit more setup.

You will need to store the animation instance in a variable and call show animation frame whenever you want the next frame to run. You can find this block under the More... category under light or by using block search.

In the example below, we store the Theater Chase animation and we show a new frame in a loop if button A is pressed.

Theater Chase animation

Copy Code 
let anim: light.NeoPixelAnimation = null
loops.forever(function () {
    if (input.buttonA.isPressed()) {
        light.pixels.showAnimationFrame(anim)
    }
})
anim = light.animation(LightAnimation.TheaterChase

Photon

Photon is a simple logo turtle for NeoPixels. The Photon is a color cursor that leaves a trail color as it moves. You can move Photon forward or backward, change the trail color or lift/lower the pen.

In the example below, we repeat 9 times a move forward and a color shift. Then, we set the photon in eraser mode and have it go back to clear up the circle. This creates a cool effect of bouncing rainbow animation.

To get started, try playing with these two blocks:

  • Photon forward let you move the photon on the LED strip
  • Photon set color lets you change the color hue from 0 to 255.

Photon is inspired from LightLogo from Brian Silverman

Copy Code 
let item = 0
loops.forever(function () {
    light.pixels.setPhotonMode(PhotonMode.PenDown)
    for (let i = 0; i < 9; i++) {
        light.pixels.photonForward(1)
        light.pixels.setPhotonColor(item)
        item += 5
        loops.pause(50)
    }
    light.pixels.setPhotonMode(PhotonMode.Eraser)
    for (let i = 0; i < 9; i++) {
        light.pixels.photonForward(-1)
        loops.pause(50)
    }
})
item =

Photon is inspired from LightLogo from Brian Silverman.

External Pixels

MakeCode provides a rich library to more NeoPixel strips (see the API reference) connected on the pins of the Circuit Playground.

If you want to support an external NeoPixel strip, not the 10 built-in LEDs, you can create a NeoPixelStrip instance and store it in a variable. You can configure the number and type of LEDs.

Copy Code 
// mount an external Neopixel strip on pin A1 with 24 RGB pixels
let strip = light.createNeoPixelStrip(pins.A1, 24, NeoPixelMode.RGB);

The example below mounts a NeoPixel strip on pin A1 and turns it to blue or red when buttons A or B are pressed.

To set all the colors on the pixels, use setAll:

Copy Code 
// show blue on all pixels
strip.setAll(Colors.Blue)

You can also use the set pixel color block to set an individual pixel color.

Copy Code 
// set colors one by one
for(let i = 0; i &lt; strip.length(); ++i) {
    strip.setPixelColor(i, Colors.Green);
}

The example mounts a NeoPixel strip

Copy Code 
// mount an external Neopixel strip on pin A1 with 24 RGB pixels
let strip = light.createNeoPixelStrip(pins.A1, 24, NeoPixelMode.RGB);

input.buttonA.onEvent(ButtonEvent.Down, function () {
    // show blue on all pixels
    strip.setAll(Colors.Blue)
})

input.buttonB.onEvent(ButtonEvent.Down, function () {
    // show red on all pixels
    strip.setAll(Colors.Red)
}

Ranges

When working with long strips of NeoPixel, it is quite useful to chunk them into ranges and apply independent colors and animations to them. The range allows you to create a new NeoPixel strip instance over a subset of the pixels.

Copy Code 
// mount an external Neopixel strip on pin A1 with 24 RGB pixels
let strip = light.createNeoPixelStrip(pins.A1, 24, NeoPixelMode.RGB);

// create 2 ranges for each half of the strip
let head = strip.range(0, 12);
let tail = strip.range(12, 12);

Once you have your rangers defined, you can easily apply colors and animation without worrying about complicated index computations.

Copy Code 
// turn on 1 pixel on each range
head.setPixelColor(0, Colors.Blue)
tail.setPixelColor(11, Colors.Red)

The example below create 2 ranges and moves the pixels in opposite directions on each of them.

Example creates 2 ranges and moves the pixels

Copy Code 
// mount an external Neopixel strip on pin A1 with 24 RGB pixels
let strip = light.createNeoPixelStrip(pins.A1, 24, NeoPixelMode.RGB);

// create 2 ranges for each half of the strip
let head = strip.range(0, 12);
let tail = strip.range(12, 12);

// turn on 1 pixel on each range
head.setPixelColor(0, Colors.Blue)
tail.setPixelColor(11, Colors.Red)

// rotate both ranges in opposite direction
loops.forever(function () {
    head.move(LightMove.Rotate, 1)
    tail.move(LightMove.Rotate, -1)
    loops.pause(50)
}

Buffering

By default, all operations on the NeoPixels are immediately transferred to the lights. This works great to get started and for a small number of pixels. However, for a large number of lights and for precise control of the timings, you might want to decide when to send the updates to the hardware.

To turn on buffering, call setBuffered.

Copy Code 
...
strip.setBuffered(false)

Once buffering is on, you need to call show to send the color updates into the NeoPixels.

Copy Code 
... some operations on the colors
strip.show();

call show to send the color updates into the NeoPixels

Copy Code 
// mount an external Neopixel strip on pin A1 with 24 RGB pixels
let strip = light.createNeoPixelStrip(pins.A1, 24, NeoPixelMode.RGB);
strip.setBuffered(false);

// move and show
loops.forever(function () {
    strip.move(LightMove.Rotate)
    strip.show();
}

Bitmap animations (Beta)

This is a cool-yet still rather experimental feature!

NeoAnim is a way to encode NeoPixel animation into bitmaps. It's a surprisingly easy way to design cool animation (once you wrap your head around the concept).

The pxt-neoanim implements this technique for MakeCode. It also comes with a converter that takes an image and turns into the JavaScript code that MakeCode can understand.

The image below is an example of possible animation and the editor shows the animation once converted.

example of animation and the editor

Copy Code 
const animation = light.animationSheet
(hex`2e0a2188ff004cfc024cfd004cfe004cfe8c4df8064dfc8b4dfe024efa8a4ff6084ffe0550f20d50f40b50f98950fe0051e60a51f20551f78851f80b52ed1152f40e53d91053f48654e91654fb0d55ee
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loops.forever(() => {
    light.pixels.showAnimationFrame(animation);
})
制造商零件编号 3333
CIRCUIT PLAYGROUND EXPRESS
Adafruit Industries LLC
¥203.09
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