FastLED HSV Dials - Example project showing how to use Hue, Saturation, and Value to create color.

FastLED-HSV-Dials.ino

#include "FastLED.h"

// How many leds in your strip?
#define NUM_LEDS 12

#define DATA_PIN 0

#define HUE_PIN A4
#define SAT_PIN A5
#define VAL_PIN A6

// Define the array of leds
CRGB leds[NUM_LEDS];

byte hue = 0;

void setup() {
  FastLED.addLeds<WS2811, DATA_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(64);
}

void loop() {
  int value = 0;

  value = analogRead(HUE_PIN); // read the value from the potentiometer
  byte hue = map(value, 0, 1023, 0, 255); // scale value from 0-1023 to 0-255

  value = analogRead(SAT_PIN); // read the value from the potentiometer
  byte sat = map(value, 0, 1023, 0, 255); // scale value from 0-1023 to 0-255

  value = analogRead(VAL_PIN); // read the value from the potentiometer
  byte val = map(value, 0, 1023, 0, 255); // scale value from 0-1023 to 0-255

  CHSV color = CHSV(hue, sat, val);

  fill_solid(leds, NUM_LEDS, color);

  FastLED.show();
}