Controling the brightness of an RGBW LED stip with a potentiometer.

Other Hardware LEDs and Multiplexing
3

Untested.
Leo..

unsigned int potValue[5]; // five pots: dim=A0 red=A1 green=A2 blue=A3 white=A4
const byte redPin = 11, greenPin = 10, bluePin = 9, whitePin = 6;
byte redValue, greenValue, blueValue, whiteValue;
byte prevRed, prevGreen, prevBlue, prevWhite;

void setup() {
  Serial.begin(115200);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
  pinMode(whitePin, OUTPUT);
}

void loop() {
  for (byte i = 0; i < 5; i++) potValue[i] = analogRead(i) >> 2;
  redValue = potValue[0] * potValue[1] / 255;
  if (redValue != prevRed) {
    analogWrite(redPin, redValue);
    prevRed = redValue;
    printRGBW();
  }
  greenValue = potValue[0] * potValue[2] / 255;
  if (greenValue != prevGreen) {
    analogWrite(greenPin, greenValue);
    prevGreen = greenValue;
    printRGBW();
  }
  blueValue = potValue[0] * potValue[3] / 255;
  if (blueValue != prevBlue) {
    analogWrite(bluePin, blueValue);
    prevBlue = blueValue;
    printRGBW();
  }
  whiteValue = potValue[0] * potValue[4] / 255;
  if (whiteValue != prevWhite) {
    analogWrite(whitePin, whiteValue);
    prevWhite = whiteValue;
    printRGBW();
  }
}

void printRGBW() {
  Serial.print("Dim:");
  Serial.print(potValue[0]);
  Serial.print(" Red:");
  Serial.print(redValue);
  Serial.print(" Green:");
  Serial.print(greenValue);
  Serial.print(" Blue:");
  Serial.print(blueValue);
  Serial.print(" White:");
  Serial.println(whiteValue);
  delay(100);
}