RGBshow() - Super Smooth Full Color LED Fading

I was working on putting together OSCars lighting system and of course I had to get my RGB led set up first. Several months back I was looking online for a better method to fade an LED. I cant remember where I found this or I would happily give the creator credit for it.

int periode = 5000;

time = millis();

value = 128+127*cos(2*PI/periode*time);

analogWrite(ledpin, value) ;

So basically what happens is once you reach 'value =' it maps that variable to a point on a wave. As the code loops that point will follow along the wave thanks to 'time=mills();' which uses the Arduinos built in running counter to make it both smooth as well as non-blocking. 


The generated wave rises and falls symetrically and you can control the time from the start to the end of the wave by adjusting the 'periode' value. A value of 1000 will be about one second.

So with the following code  you should be able to smoothly fade one led from minimum to full brightness back to minimum in 5 seconds...

const int ledpin = 13;
long time=0;
int periode = 5000;
int led_val = 0;

void setup() {
//nothing
}

void loop() {
rgbShow();
// Im going to run it as a function for ease of integration
analogWrite(ledpin, led_val)
//we will constantly write the value thats generated from the function to the ledpin
}

void rgbShow() {
time = millis();
value = 128+127*cos(2*PI/periode*time);
led_val = value;
}

But I want to use it with a full color LED!


So were just going to add two more variables called displace and displace2, these two values will offset the start of the wave - from the start of the first wave - by a value of milliseconds.

// declare before setup
int displace = 250;
int displace2 = 500;

//....setup()

 This will allow us to generate three waves for the three colors of our led.

void rgbShow() {

time = millis();
  value = 128+127*cos(2*PI/periode*time);
  value2 = 128+127*cos(2*PI/periode*(displace-time));
  value3 = 128+127*cos(2*PI/periode*(displace2-time));
redval = value;      
greenval = value2;    
blueval = value3;      

}

 Expirement with the values and see what you get!