By: Andrew Tuline

A Fast Introduction to the ArduinoAnd Addressable LED Strips

Spark FUN

The Arduino Family

Early Projects

Too Many Pins

Someone has more skills, patience and time than I do!

Addressable LED Strips

• Addressable LED strips provide circuitry to communicate serially

• Each LED has a chip to receive, decode, drive LED’s and propagate data

Form Factors

Also 30, 60, 144 pixels/m

Enter Adafruit

• Adafruit has branded WS2812’s and APA102C’s

• They are called NeoPixels and DotStars

Adafruit sells addressable LED’s in many shapes and sizes!

NeoPixels vs. DotStars

DotStars

• Data and clock pin

• High data rate

• Interrupt compatible

• More $$

• Currently strip only

• APA102C

https://learn.adafruit.com/adafruit-dotstar-leds/overview

NeoPixels

• Data pin only

• Slow data rate

• Not interrupt compatible

• Less $$

• Strips and more

• WS2812 & WS2812B

A Typical Addressable Strip

Strips include:

• WS2812, WS2812B• APA102, APA102C• WS2801, others . .

12V accent lighting strips don’t count!

Simple APA102C Connection

D12 –D11 –

5V –Gnd –Vin –

Data inClock in5VGnd, Battery -Battery +

If using the Arduino 5V pin, keep the strip SHORT and reduce brightness!

Addressable LED Libraries

• Adafruit NeoPixel library

• Adafruit DotStar library

And then there’s:

• FastLED

Why FastLED?

• FastLED is a fast, easy-to-use Arduino library for programming addressable LED strips.

• It supports multiple microcontroller platforms.• It supports multiple addressable LED types.• It has a lots of of function calls.• FastLED is used by thousands of developers.• The developers count clock cycles.

Do a YouTube search for ‘FastLED’

Downloading FastLED

• Follow the link at www.fastled.io

• The current version is on GitHub at:https://github.com/FastLED/FastLED

• Download the zip file

• Extract the directory FastLED-master.

• Rename the directory from:

FastLED-master to FastLED

• Place that directory into:

C:\Program Files(x86)\Arduino\libraries

I use the development version (currently 3.1)!

FirstLight Example

• In the Arduino IDE, select

‘File | Examples | FastLED | FirstLight’

• I’m using APA102C, so I need to change some definitions

We need to configure it for our LED strip!

Modified FirstLight Code#include "FastLED.h"

#define NUM_LEDS 20#define DATA_PIN 12#define CLOCK_PIN 11uint8_t max_bright = 64;

CRGB leds[NUM_LEDS];

void setup() {FastLED.addLeds<APA102, DATA_PIN, CLOCK_PIN, BGR>(leds, NUM_LEDS);FastLED.setBrightness(max_bright);

}

void loop() {for (int count = 0; count < NUM_LEDS; count++) {

leds[count] = CRGB::White;FastLED.show();delay(100);leds[count] = CRGB::Black;

}} The white LED should march across the array.

// Include the library

// Number of LED’s// Our data pin// Our clock pin// Define brightness limiter

// Define the LED array

// Run once// Initialize the LED library

// Limit the brightness

// Run continuously// Cycle through all LED’s// Set the current one white// Show it// Wait for a bit// Set it to black

Setting LED values

• leds[9] = CRGB::Cyan; // Web colours

• leds[9].g = 255; // Just set green

• leds[0] = CRGB(255,0,0); // CRGB values (red, green, blue)

• leds[0] = 0x0000ff; // Use a long hex value

Or via HSV

• leds[9] = CSHV(hue, sat, bright); // Each goes up to 255

FastLED provides lots more ways to assign colours to LED’s

FastLED Is Just Getting Started

FastLED contains a LOT of functions including:• Random number generation

• Fast 8 and 16 bit basic math functions

• Fast trigonometry

• Setting RGB and HSV values

• fill_rainbow, fill_gradient, fading, scaling, blending, noise, palettes, palette blending, beats and more. . .

• Power management

We’re talking loads of functionality and FAST

Rainbow March#include "FastLED.h"

#define LED_DT 12 // Data & clock pin

#define NUM_LEDS 20 // Number of LED's

#define COLOR_ORDER BRG // Change the order as necessary

#define LED_TYPE WS2812 // What kind of strip are you using?

uint8_t max_bright = 64; // How bright do we want to go

struct CRGB leds[NUM_LEDS]; // Initialize our array

uint8_t thisdelay = 8; // A delay value for the sequence

uint8_t thishue = 0; // Starting hue value.

uint8_t deltahue = 5; // Difference in hue between LED’s

Use variables where possible

Rainbow March cont’d

void setup() {

LEDS.addLeds<LED_TYPE, LED_DT, COLOR_ORDER>(leds, NUM_LEDS);

FastLED.setBrightness(max_bright);

}

void loop () {

rainbow_march();

FastLED.show();

delay(thisdelay); // or FastLED.delay(thisdelay);

}

void rainbow_march() {

thishue++;

fill_rainbow (leds, NUM_LEDS, thishue, deltahue); // FastLED does the heavy lifting

}

It boils down to just a few lines of loop code

Power Managed Rainbow March

1) In setup add:set_max_power_in_volts_and_milliamps(5, 500); // Power management set at 5V, 500mA.

2) Change delay from:delay(thisdelay); // or

FastLED.delay(thisdelay);

To:delay_at_max_brightness_for_power(thisdelay); // Power managed FastLED delay.

3) Change show from:FastLED.show();

To:show_at_max_brightness_for_power(); // Power managed display of LED's.

More FastLED Demos

• FastLED provides several demos with the library

• I’ve also written several demos downloadable at:

https://github.com/atuline/FastLED-Demos

• There’s loads of other demos available

The FastLED community is at Google+

My Demos include

• one_sine demo

• pop_fade_demo

• ripple

• two_sin_demo

• noise16_demo

• three_sin_demo

• rainbow_march_demo

• aalight

aalight provides many routines, IR, keyboard, serial and button input

• fht_log

• matrix_demo

• soundbracelet

• soundmems

• and more. .

High School Trigonometry

• An increasing linear input value yields a sine wave output value

• Map the output to brightness or location

• Change frequency, phase, amplitude

• Mix multiple sine waves

• 8 or 16 bit

Why count pixels when you can use sine waves

More Topics

• Power issues• Data line conditioning• Troubleshooting, getting support• Diffusers• 2D matrix• POV• Sound reactive, MSGEQ7 vs FFT• Other platforms (ie. Teensy 3.1, Octo WS2811)• IR and other kinds of control• DMX• Loop friendly routines

LED Research

• fastled.io

• github.com

• pastebin.com

• arduino.cc/tutorial

• playground.arduino.cc

• learn.adafruit.com

I mostly use my Google-fu

Sources for Parts

• Lee’s Electronics

• Adafruit

• Sparkfun

• eBay

• Aliexpress

All it takes is a VISA card and your imagination

Demo Time