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/*
* "Coffee-cup" Color Mixer:
* Code for mixing and reporting PWM-mediated color
* Assumes Arduino 0004 or higher, as it uses Serial.begin()-style communication 
* 
* Control 3 LEDs with 3 potentiometers
* If the LEDs are different colors, and are directed at diffusing surface (stuck in a
*   a Ping-Pong ball, or placed in a paper coffee cup with a cut-out bottom and 
*   a white plastic lid), the colors will mix together.
*
* When you mix a color you like, stop adjusting the pots.
* The mix values that create that color will be reported via serial out.
*
* Standard colors for light mixing are Red, Green, and Blue, though you can mix 
*   with any three colors; Red + Blue + White would let you mix shades of red, 
*   blue, and purple (though no yellow, orange, green, or blue-green.)
*
* Put 220 Ohm resistors in line with pots, to prevent circuit from 
*   grounding out when the pots are at zero
*/

// Analog pin settings
int aIn = 0;    // Potentiometers connected to analog pins 0, 1, and 2
int bIn = 1;    //   (Connect power to 5V and ground to analog ground)
int cIn = 2;  

// Digital pin settings
int aOut = 9;   // LEDs connected to digital pins 9, 10 and 11
int bOut = 10;  //   (Connect cathodes to digital ground)
int cOut = 11;  

// Values
int aVal = 0;   // Variables to store the input from the potentiometers
int bVal = 0;  
int cVal = 0;  

// Variables for comparing values between loops
int i = 0;            // Loop counter
int wait = (1000);    // Delay between most recent pot adjustment and output

int checkSum     = 0; // Aggregate pot values
int prevCheckSum = 0;
int sens         = 3; // Sensitivity theshold, to prevent small changes in 
                      // pot values from triggering false reporting
// FLAGS
int PRINT = 1; // Set to 1 to output values
int DEBUG = 1; // Set to 1 to turn on debugging output

void setup()
{
  pinMode(aOut, OUTPUT);   // sets the digital pins as output
  pinMode(bOut, OUTPUT);   
  pinMode(cOut, OUTPUT); 
  Serial.begin(9600);     // Open serial communication for reporting
}

void loop()
{
  i += 1; // Count loop

  aVal = analogRead(aIn) / 4;  // read input pins, convert to 0-255 scale
  bVal = analogRead(bIn) / 4; 
  cVal = analogRead(cIn) / 4;  

  analogWrite(aOut, aVal);    // Send new values to LEDs
  analogWrite(bOut, bVal);
  analogWrite(cOut, cVal);

  if (i % wait == 0)                // If enough time has passed...
  {    
    checkSum = aVal+bVal+cVal;      // ...add up the 3 values.
    if ( abs(checkSum - prevCheckSum) > sens )   // If old and new values differ 
                                                  // above sensitivity threshold
    {
      if (PRINT)                    // ...and if the PRINT flag is set...
      {
        Serial.print("A: ");        // ...then print the values.
        Serial.print(aVal);         
        Serial.print("\t"); 
        Serial.print("B: ");        
        Serial.print(bVal);
        Serial.print("\t");
        Serial.print("C: ");                
        Serial.println(cVal); 
        PRINT = 0;
      }
    }  
    else
    {
      PRINT = 1;  // Re-set the flag   
    } 
    prevCheckSum = checkSum;  // Update the values

    if (DEBUG)   // If we want debugging output as well...
    {
      Serial.print(checkSum);
      Serial.print("<=>");
      Serial.print(prevCheckSum);
      Serial.print("\tPrint: ");
      Serial.println(PRINT);
    }
  }
}