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RGBEffects

A library for displaying colour effects using RGB LEDs.
The main motivation for writing this was to learn how to write an Arduino library, and tidy up the code for a remote controlled LED lamp project.

Please note I had no experience with C++ before this. Apologies if the source makes you weep. Pull requests gladly accepted.

Installation

Assuming you are using the standard Arduino IDE, clone or download the project, then copy it into your Arduino libraries directory. For more information, see the Arduino Libraries Guide.

When the library is installed properly, it will be available in the Sketch > Import library list.

There are examples included as part of the library. Once the library is installed, the examples can be viewed in File > Examples > RGBEffects > ...

Usage

RGBEffects is concerned with calculating the next colour in an effect and displaying that colour. It is up to you to control the frequency that the update() method is called. The usual way to do this is use Arduinos delay(ms) function.

Note that you do not need to set the red, green and blue pin modes, this will be done in the rgbEffects initialisation.

Examples

#include <RGBEffects.h>

int redPin = 3;
int greenPin = 5;
int bluePin = 6;

int updateCount = 0;

RGBEffects rgbEffects( redPin, greenPin, bluePin );

void setup(){
  Serial.begin(115200);
}

void loop(){
  rgbEffects.update();
  updateCount++;

  // calls update 100 times before changing to the next effect.
  if(updateCount >= 100){
    updateCount = 0;
    rgbEffects.nextEffect();
    Serial.println("Changing effect.");
  }

  // 200ms delay between each update call.
  delay(200);
}
#include <RGBEffects.h>

const int redPin = 3;
const int greenPin = 5;
const int bluePin = 6;

int updateDelay = 500;

RGBEffects rgbEffects( redPin, greenPin, bluePin );

void setup(){
  rgbEffects.setEffect(EFFECT_BLINK);
}

void loop(){
  rgbEffects.update();
  delay(updateDelay);
}

API

The RGBEffects class has the following public API.

  • RGBEffects(int redPin, int greenPin, int bluePin)
    Class constructor. redPin, greenPin, and bluePin are the pin numbers for the LED attached to the Arduino. The default effect is EFFECT_RAINBOW
  • nextEffect()
    Changes to the next mode, as defined by the ordering in RGBEffects.h. It will loop back to the first mode if called on the last mode.
  • setEffect(RGBEffectType effect)
    Set the effect mode to a specific effect.
  • update()
    Calculates the next colour in the effect and updates the LED.

Available Effects

  • EFFECT_OFF Turns the LEDs off.
  • EFFECT_SOLID_RED Shows a solid red colour RGB(255,0,0)
  • EFFECT_SOLID_GREEN Shows a solid green colour RGB(0,255,0)
  • EFFECT_SOLID_BLUE Shows a solid blue colour RGB(0,0,255)
  • EFFECT_SOLID_YELLOW Shows a solid yellow colour RGB(255,255,0)
  • EFFECT_SOLID_PURPLE Shows a solid purple colour RGB(148,0,211)
  • EFFECT_SOLID_VIOLET Shows a solid violet colour RGB(238,130,238)
  • EFFECT_SOLID_WHITE Shows a solid white colour RGB(255,255,255);
  • EFFECT_RAINBOW Shows the colours of the rainbow in sequence (red, orange, yellow, green, blue, indigo, violet).
  • EFFECT_FADE Fades between colours.
  • EFFECT_CUBE Transitions in steps between different colours defined by a cube.
  • EFFECT_BLINK Alternates between turning the LED off and showing blue.

Adding more effects

Adding new effects is pretty simple.

  1. Increase the size of the _effects array in RGBEffect.h
  2. Create an entry for your new effect in RGBEffectType in RGBEffects.h
  3. Create a subclass of Effect in RGBEffects.cpp
  4. Create an instance of that class in the RGBEffects constructor and add it to the _effects array in RGBEffects.cpp
  5. Add a case for your effect in the RGBEffects::setEffect method in RGBEffects.cpp

There is a commit which adds a new effect called Blink.

If you want to share your effect, send a pull request with your changes.

Debugging effects

If you want to see what colour the update call is setting, change the 0 to a 1 in the line #define DEBUG_COLOURS_ENABLED (0) at the top of RGBEffects.h.

Backlog

I am not planning to make many more changes to the library as for my current projects it works fine. Possible future work includes:

  • Refactor to reduce memory usage when running.
  • Add ability to control multiple RGB LEDs. At the moment I get around this problem by having two LEDs on a single set of pins which seems to work just swell.