Forward/Reverse Fading

Description
* Each LED has its own pot which controls the speed at which it cycles through 
* different brightness levels by determining the "jump" size between values.
* Because the LEDs calculate their output in mod 255 this has the 
* benefit of allowing you to reverse direction and go from brighter to darker
* when the jump size is bigger than 255/2 (Like when car wheels can appear
* to be spinning backwards when they are at a certain speed).
*
* Setting a pot to mid range values (between 103-153 after being converted to a
* 255 scale) will hold it's brightness level constant. Turning the pot to
* either minimum or maximum value will likewise set the LED to 0 or 255.
 
Components
1- Arduino Uno
1 - Breadboard
3 - Potentiometers
3 - LEDs (red, green, blue)
3 − 220 Ω Resistors
1 - homemade diffusor
assorted wires
 
 
Code
/*
* by Jordan Arnesen, 1 Oct 2013
*
* Control 3 LEDs with 3 potentiometers
* Each LED has its own pot which controls the speed at which it cycles through 
* different brightness levels by determining the "jump" size between values.
* Because the LEDs calculate their output in mod 255 this has the 
* benefit of allowing you to reverse direction and go from brighter to darker
* when the jump size is bigger than 255/2 (Like when car wheels can appear
* to be spinning backwards when they are at a certain speed).
*
* Setting a pot to mid range values (between 103-153 after being converted to a
* 255 scale) will hold it's brightness level constant. Turning the pot to
* either minimum or maximum value will likewise set the LED to 0 or 255.
*
*/
 
// Analog pin settings
int rIn = 0;    // Potentiometers connected to analog pins 0, 1, and 2
int gIn = 1;    //   (Connect power to 5V and ground to analog ground)
int bIn = 2;  
 
// Digital pin settings
int rOut = 3;   // LEDs connected to digital pins 9, 10 and 11
int gOut = 5;  //   (Connect cathodes to digital ground)
int bOut = 6;  
 
// Values
int rPot = 0;   // Variables to store the input from the potentiometers
int gPot = 0;  
int bPot = 0;  
int rVal = 0;
int gVal = 0;
int bVal = 0; 
int rInc = 0;  // Variable for brightness increment size
int gInc = 0;
int bInc = 0;
 
int wait = 500;    // Delay between increments in brightness
 
 
void setup()
{
  pinMode(rOut, OUTPUT);   // sets the digital pins as output
  pinMode(gOut, OUTPUT);   
  pinMode(bOut, OUTPUT); 
}
 
void loop()
{
 
  rPot = analogRead(rIn) / 4;  // read input pins, convert to 0-255 scale
  gPot = analogRead(gIn) / 4; 
  bPot = analogRead(bIn) / 4;  
  
  if ( rPot < 103|| rPot > 153) rVal += rPot;   // increment currrent brightness by Pot value
  if ( gPot < 103|| gPot > 153)  gVal += gPot;  // if Pot between 103-153 keep brightness same 
  if ( bPot < 103|| bPot > 153)  bVal += bPot;
 
  if ( rPot == 0 || rPot == 255) rVal = rPot;  // if Pot is at min/max set LED to min/max
  if ( gPot == 0 || gPot == 255) gVal = gPot;
  if ( bPot == 0 || bPot == 255) bVal = bPot;
  
    
      // Send new values to LEDs
  analogWrite(rOut, rVal);
  analogWrite(gOut, gVal);
  analogWrite(bOut, bVal);
 
  delay(wait);
 
}