// Demonstration potentiometers and RGB leds
// 9 May 2024, by Koepel, Public Domain

// Pins that support PWM to dim the leds
const int ledPins[3] = {6, 5, 3};     // pins of the R, G, B leds
const int potPins[3] = {A0, A1, A2};

void setup() 
{
  Serial.begin(115200);
  Serial.println("The demonstration sketch has started.");

  // Set the led pins as output
  for(int i=0; i<3; i++)
  {
    pinMode(ledPins[i], OUTPUT);
  }

  // The analog pins don't need a pinMode().
}

void loop() 
{
  for(int i=0; i<3; i++)
  {
    int value = analogRead(potPins[i]);
    Serial.print(value);

    // The Arduino Uno has analog inputs of 10 bits,
    // with a value from 0...1023.
    // The analogWrite is only 0...255.
    // The human eye sees the brightness
    // with a curve close to 10log.

    // scale to 0...1 to prepare for the exponential function
    float t1 = float(value) / 1023.0; 
    // convert 0...1 to 1...10 with exponential scale with base 10
    float t2 = pow( 10, t1);          
    // convert 1...10 to 0...255. Add 0.5 to 255 for rounding
    float t3 = (255.5 / 9.0 * (t2 - 1.0)); 
    int pwm = int(t3);
    analogWrite(ledPins[i], pwm);

    Serial.print(" (");
    Serial.print(pwm);
    Serial.print(")");
    if(i != 2)
      Serial.print(",   ");
  }
  Serial.println();

  delay(250);
}