My first Arduino sketch

gistfile1.hpp

// Knobber
// Hook up a potentiometer to tri-color LED

int redPin   = 9;   // red LED, digital pin 9
int greenPin = 10;  // green LED, digital pin 10
int bluePin  = 11;  // blue LED, digital pin 11
int potPin   = 0;   // potentiometer, analog pin 0

int redVal   = 1;
int greenVal = 1;
int blueVal  = 1;
int potVal;

void setup()
{
  pinMode(redPin,   OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin,  OUTPUT);
}

void loop()
{
  potVal = analogRead(potPin);

  if (potVal < 255)
  {
    redVal   = (255 - potVal);
    greenVal = (potVal == 0 ? 1 : potVal);
    blueVal  = 1;
  }
  else if (potVal < 510)
  {
    redVal   = 1;
    greenVal = (510 - potVal);
    blueVal  = (1 + (potVal - 255));
  }
  else if (potVal < 765)
  {
    redVal   = (1 + (potVal - 510));
    greenVal = 1;
    blueVal  = (765 - potVal);
  }
  else
  {
    redVal   = 0;
    greenVal = 0;
    blueVal  = 0;
  }

  analogWrite(redPin,   redVal);
  analogWrite(greenPin, greenVal);
  analogWrite(bluePin,  blueVal);
}