Description

First, I added three potentiometers to control the brightness of each LED individually. Next, I remapped the potentiometers. In this version, pot 2 controls "brightness" and pot 3 controls "step delay". Pot 1 is the One Knob that controls hue, by mapping a brightness function for each LED to pot 1. A sin function (offset for each LED) handles this nicely. "Brightness" is accomplished with a percentage multiplier, and "Step delay" is simply a delay between LED updates.

This project brought out some hardware limitations of Arduino. In the project's first iteration, each LED employed a complete set of calculations. This duplication slowed Arduino noticeably, to the extent that it was frustrating to use. Streamlining the script by consolidating calculations improved performance significantly.

Materials

• 3 LEDs
• 3 potentiometers
• 1 resistor
• wires
• Arduino

Code

/*
 * Pot 1 changes color of all three LEDs according to a sin function
 * Pot 2 changes brightness of all three LEDs
 * Pot 3 controls a variable "step delay" between updates
 */

//select pot input pins
int pot1Pin = 0;
int pot2Pin = 1;
int pot3Pin = 2;

//variables to store values from pots
int pot1Val = 0;
int pot2Val = 0;
int pot3Val = 0;
int pot2Adj = 0;

//select LED output pins
int led1Pin = 9; 
int led2Pin = 10;
int led3Pin = 11;

//offset for calculating pin colors
int led2Offset = 2.1;   // roughly 2π/3
int led3Offset = 4.2;   // roughly 4π/3

int multiplier = 0;
int pot1Rad = 0;

void setup() {
   pinMode(led1Pin, OUTPUT);  // declare the led1Pin as an OUTPUT
   pinMode(led2Pin, OUTPUT);  // declare the led2Pin as an OUTPUT
   pinMode(led3Pin, OUTPUT);
}

void loop() {
   pot1Val = analogRead(pot1Pin);   // read the value from pot 1, between 0 - 1024, for hue
   pot1Rad = pot1Val/163;           // converts pot 1 value into a radian value (0-2π)
   pot2Val = analogRead(pot2Pin);   // read the value from pot 2, between 0 - 1024, for dimming
   pot3Val = analogRead(pot3Pin);   // read the value from pot 3, for blinking
   multiplier = 128*pot2Val/1024;   // converts sin value to brightness, including dimming factor
   analogWrite(led1Pin, (sin(pot1Rad)+1)*multiplier); // dim LED to value from pot1
   analogWrite(led2Pin, (sin(pot1Rad-led2Offset)+1)*multiplier); // dim LED to value from pot1
   analogWrite(led3Pin, (sin(pot1Val-led3Offset)+1)*multiplier); // dim LED to value from pot1
   delay(pot3Val);                  // stop the program for some time
}

Picture