Linear Potentiometer to quadratic CCT Light - Arduino Controlled

cct_linear_light.ino

// Uses a linear potentiometer to adjust the brightness of an CCT light connected to the arduino.
// the darker the light, the warmer the color temperature gets.
// The brightness get's adjusted quadratically to the potentiometer value.
// This is ideal for a night lamp with fine control in the lower spectrum but the ability to use full brightness at day.

#define PIN_WW 5
#define PIN_CW 6
#define PIN_IN A0
#define MAX_BRIGHTNESS 255
#define threshold 10

void setup() {
  pinMode(PIN_IN, INPUT);
  pinMode(PIN_WW, OUTPUT);
  pinMode(PIN_CW, OUTPUT);
}

void loop() {
  int sensorValue = analogRead(PIN_IN);
  if(sensorValue <= threshold){
    analogWrite(PIN_WW, 0);
    analogWrite(PIN_CW, 0);
  }else{
    float x = map(sensorValue - threshold, threshold, 1024, 0, 1024);
    float brightness = pow(float(x) * 0.016, 2);
    float ratio = pow(brightness / MAX_BRIGHTNESS, 2);
    analogWrite(PIN_WW, min(int(brightness), MAX_BRIGHTNESS));
    analogWrite(PIN_CW, min(int(ratio * brightness), MAX_BRIGHTNESS));
  }
}