RGB_controller.ino

int plus = 2;
int gpin = 0;
int rpin = 1;
int bpin = 4;

float red = 0;
float green = 0;
float blue = 0;

int stage = 0;
float numColors = 128;
float frequency = 0;
float i = 0;

boolean dir = true;

long lastTime = 0;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(plus, OUTPUT);
  pinMode(gpin, OUTPUT);
  pinMode(rpin, OUTPUT);
  pinMode(bpin, OUTPUT);
  digitalWrite(plus, HIGH);
  frequency = 5/numColors;
}

void loop() {
  analogWrite(rpin, red);
  analogWrite(gpin, green);
  analogWrite(bpin, blue);
  
  if (millis() - lastTime > 100) {
    lastTime = millis();
    
    red = sin(frequency * i) * (127.0) + 128.0;
    green = sin(frequency * i + 2.0) * (127.0) + 128.0;
    blue = sin(frequency * i + 4.0) * (127.0) + 128.0;
    
    if (dir) {
      i = i + 1;
    }
    else {
      i = i - 1;
    }
    
    
    if (i > numColors) {
      dir = !dir;
    }
  }
}