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The Magic Name-to-Color Transformer

kilian.moser's picture
Wed, 09/14/2011 - 07:05 — kilian.moser

 

/*
 * The Magic Name to Color Transformer
 *
 * Type in any name (or string) and see what color correspondence it has.
 * Type ~ to toggle debug mode.
 *
 * Theory and Practise of Tangible User Interfaces
 * Lab Assignment 2
 *
 * Martin Kiechle, Kilian Moser
 * 9/13/2011
 */
 
/*
 * variables and allocations
 */
 
// CRC table
unsigned crctbl[] = {0x0000, 0x1081, 0x2102, 0x3183, 
                     0x4204, 0x5285, 0x6306, 0x7387, 
                     0x8408, 0x9489, 0xa50a, 0xb58b, 
                     0xc60c, 0xd68d, 0xe70e, 0xf78f}; 
                     
// Output
int redPin   = 9;   // Red LED,   connected to digital pin 9
int greenPin = 10;  // Green LED, connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11
 
// helper vars
int i = 0;   
int DEBUG = 0;
 
// string and color transformations
char inString[100];
unsigned short checksum;
float hue;
int r,g,b;
int iHue;
 
 
// setting it all up
void setup()
{
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT); 
  Serial.begin(9600);  // ...set up the serial ouput on 0004 style
  Serial.println("THE MAGIC NAME-TO-COLOR TRANSFORMER: ");
  Serial.println("-------------------------------------- ");
  Serial.println("Enter ~ for extended information ");
  Serial.println("-------------------------------------- ");
  Serial.print("Enter your name: ");
}
 
 
// main loop
void loop()
{
  memset(inString, 0, 100);      // some initializations
  readSerialString(inString);    // read in some string
  if(*inString != 0){
    if(*inString == '~'){
      DEBUG ^= 1;                // debug toggle symbol
      Serial.println("debug mode switched");
    }
    else{
      checksum = calc_crc((unsigned char*)inString, getStrLength(inString));  // calc checksum
      Serial.println(inString);
      
      hue = checksum * 0.005478;  // transform 2 byte checksum to a 0-359 equivalent
      HSVtoRGB(&r, &g, &b, hue);  // color space conversion
      
      analogWrite(redPin, r);     // color output
      analogWrite(greenPin, g); 
      analogWrite(bluePin, b);
      
      // text interface
      if(DEBUG){
        Serial.print("The CRC checksum of your name is: 0x");
        Serial.println(checksum, HEX);
        Serial.print("The HSV hue value for the CRC is: ");
        iHue = floor(hue);
        Serial.println(iHue, DEC);
        Serial.print("The resulting RGB values are: Red: ");
        Serial.print(r, DEC);
        Serial.print(" Green: ");
        Serial.print(g, DEC);
        Serial.print(" Blue: ");
        Serial.println(b, DEC);    
      }
    }
    Serial.println("####################################");
    Serial.print("Enter your name: ");
  }
  
  delay(500);  // wait a bit, for serial data
}
 
// function for reading an input from the serial interface
void readSerialString (char *strArray) {
  int i = 0;
  if(!Serial.available()) {
    return;
  }
  while (Serial.available()) {
    strArray[i] = Serial.read();
    i++;
  }
}
 
// function for getting the length of a string
unsigned getStrLength (char *strArray) {
  int i = 0;
  while(*strArray != 0){
    strArray++;
    i++;
  }
  return i;
}
 
// function for calculating the CRC CCITT checksum of a string. 
unsigned short calc_crc(unsigned char *ptr, unsigned length) 
  
{ 
  unsigned short crc; 
  unsigned short i; 
  unsigned char pos,ch; 
  
  crc = 0xffff;  /* precondition crc */ 
  for (i = 0; i < length; i++,ptr++) { 
    ch = *ptr; 
    pos = (crc ^ ch) & 15; 
    crc = ((crc >> 4) & 0x0fff) ^ crctbl[pos]; 
    ch >>= 4; 
    pos = (crc^ch) & 15; 
    crc = ((crc >> 4) & 0xffff) ^ crctbl[pos]; 
  } 
  crc = ~crc;  /* post condition */ 
  crc = (crc << 8) | (crc >> 8); /* bytewise reverse */ 
  return crc; 
}
 
// color space conversion HSV to RGB --> http://en.wikipedia.org/wiki/HSL_and_HSV
void HSVtoRGB(int *R, int *G, int *B, float h){
   float s=1;
   float v=1;
   float r,g,b;
   int i;
   float f, p, q, t;
  
   if( s == 0 ) 
    {
  r = g = b = v;
  return;
  }
  
   h /= 60;
   i = floor( h );
   f = h - i;
   p = v * ( 1 - s );
   q = v * ( 1 - s * f );
   t = v * ( 1 - s * ( 1 - f ) );
  
  switch( i ){
    case 0: r = v; g = t; b = p; break;
    case 1: r = q; g = v; b = p; break;
    case 2: r = p; g = v; b = t; break;
    case 3: r = p; g = q; b = v; break;
    case 4: r = t; g = p; b = v; break;
    default: r = v; g = p; b = q; break;
  }
   *R = r * 255;
   *G = g * 255;
   *B = b * 255;
}
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