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Lab 2: Diffuser

Posted by sgeiger

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Description

Use the Arduino to input the name of a color from serial, and then set the intensities of red, blue, and green light emitting diodes to match.  Create a diffuser to evenly blend the light together.

Components Used

  • 3 Light Emitting Diode (LED)
  • 3 Resistors
  • 1 Styrofoam cup
  • 1 Coffee filter
     

Arduino Code

 

/* 
 * Text-based color dimmer
 * ---------------
 * Serial text commands control the brightness of R,G,B LEDs 
 *
 * Command structure is "<colorText>", where "colorText" is
 * a lowercase color
 * E.g. "red"   turns the red LED on to full brightness.  
 *      "magenta" turns the red and blue LEDs on to full brightness
 *      "indigo"  turns the red LED to 1/3 brightness, blue LED to 1/2 brightness
 *
 * Created 5 Feb 2011
 * CC-BY 2011 R.Stuart Geiger, stuart@stuartgeiger.com
 *
 * Based on code by:
 * copyleft 2006 Tod E. Kurt <tod@todbot.com
 
char serInString[20];  
char colorCode[20];
char colorName[20];
int colorVal;
 
int redPin   = 10;   // Red LED,   connected to digital pin 9
int greenPin = 9;  // Green LED, connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11
 
int rDec=0;
int bDec=0;      //intensity of the target color's R,G,B values in decimal, 0-255
int gDec=0;
 
int rDecPrev=0;
int bDecPrev=0;      //intensity of the previous color's R,G,B values in decimal, 0-255
int gDecPrev=0;
 
 
void setup() {
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT);
  Serial.begin(9600);           // Tried to TURN IT UP TO 11(5200) for faster fades. Bad idea.
  analogWrite(redPin,   255);   // set them all to full brightness
  analogWrite(greenPin, 255);   // set them all to full brightness
  analogWrite(bluePin,  255);   // set them all to full brightness
  Serial.println("enter the name of a color in lowercase (e.g. 'red' or 'cyan') :");  
 
}
 
void loop () {  
 
  
  
  // clear all strings
  memset(serInString, 0, 20);
  memset(colorCode,0,20);
  memset(colorName,0,20);
 
  // read the serial port and create a string out of what you read
  readSerialString(serInString);
 
  if(serInString[0]>0){  //if we've actually got something coming through the serial...
 
    // copy the input from the serial to two variables
    // because we have to use pointers with functions
 
    strcpy(colorCode,serInString);  
    strcpy(colorName,serInString);
 
 
    //Call function to turn the color name string into its corresponding HTML hex color
    textToRGB(colorCode);  
 
 
    // store old RGB intensity values
    rDecPrev=rDec;
    gDecPrev=gDec;
    bDecPrev=bDec;
    
    // reset RGB intensity values
    rDec=0;
    gDec=0;
    bDec=0;
 
    // step through the hex color string character by character
    // why yes, I am a fan of rube goldberg, how did you know?
    // okay not really, I just miss python :(
    rDec=(16*hexToDec(colorCode[0]))+hexToDec(colorCode[1]);  
    gDec=(16*hexToDec(colorCode[2]))+hexToDec(colorCode[3]);
    bDec=(16*hexToDec(colorCode[4]))+hexToDec(colorCode[5]);
 
 
    //if there is an error IDing colors, hexToDec will throw a -1 and make something negative
    if(rDec>=0 && gDec>=0 && bDec>=0){  
 
      // verbosity
      Serial.print("setting color ");
      Serial.print(colorName);
      Serial.print(" to ");
      Serial.print(rDec);
      Serial.print(" ");
      Serial.print(gDec);
      Serial.print(" ");
      Serial.print(bDec);
      Serial.println();
 
      // fade from the previous color to the target color, write the color to pins
      while(rDecPrev!=rDec || gDecPrev!=gDec || bDecPrev!=bDec) {
        
        if(rDecPrev > rDec) {rDecPrev--;}
        if(gDecPrev > gDec) {gDecPrev--;}  
        if(bDecPrev > bDec) {bDecPrev--;}
        
        if(rDecPrev < rDec) {rDecPrev++;}
        if(gDecPrev < gDec) {gDecPrev++;}  
        if(bDecPrev < bDec) {bDecPrev++;}
        
        analogWrite(redPin, rDecPrev);
        analogWrite(greenPin, gDecPrev);
        analogWrite(bluePin, bDecPrev);
 
 
         // more verbosity
         Serial.print("setting color ");
         Serial.print(colorName);
         Serial.print(" to ");
         Serial.print(rDecPrev);
         Serial.print(" ");
         Serial.print(gDecPrev);
         Serial.print(" ");
         Serial.print(bDecPrev);
         Serial.println();
        
         delay(1);
      }
      
      analogWrite(redPin, rDec);
      analogWrite(greenPin, gDec);
      analogWrite(bluePin, bDec);
 
      Serial.println("----------------------------------------------");
 
    }
    else {
      Serial.print("I don't know the color:");
      Serial.println(colorName);
    }
 
    serInString[0] = 0;  // apparently this is *really* necessary
 
 
 
  }
  delay(100);  // wait a bit, you've got time 
 
}
 
//read a string from the serial and store it in an array
// you must supply the array variable
void readSerialString (char *strArray) {
  int i = 0;
  if(!Serial.available()) {
    return;
  }
 
  while (Serial.available()) {
 
    strArray[i] = Serial.read();
    i++;
  }
}
 
//convert a single hex character into its corresponding int value
//this is ridiculous
int hexToDec(char hexChar) {
  switch(hexChar) {
  case '0':
    return 0;
  case '1':
    return 1;
  case '2':
    return 2;
  case '3':
    return 3;
  case '4': return 4;
  case '5':
    return 5;
  case '6':
    return 6;
  case '7':
    return 7;
  case '8':
    return 8;
  case '9':
    return 9;
  case 'A':
    return 10;
  case 'B':
    return 11;
  case 'C':
    return 12;
  case 'D':
    return 13;
  case 'E':
    return 14;
  case 'F':
    return 15;   
  }
  return -1;  //if another character, return error
}
 
 
//convert a string containing a color name into its corresponding HTML hex color value
//Taken from list of color names in the HTML spec, from http://www.w3schools.com/html/html_colornames.asp
//not all HTML color values are here, just the good ones
//returns ZZZZZZ if color is not found
void textToRGB(char *colorText) {
 
  char hex[7];
  
  //compare the input string to color names, if it is the same, copy it into temp string
  if (strcmp(colorText,"azure") == 0) {
    strcpy(hex,"F0FFFF");
  }
  else if (strcmp(colorText,"beige") == 0) {
    strcpy(hex,"F5F5DC");
  }
  else if (strcmp(colorText,"black") == 0) {
    strcpy(hex,"000000");
  }
  else if (strcmp(colorText,"blue") == 0) {
    strcpy(hex,"0000FF");
  }
  else if (strcmp(colorText,"brown") == 0) {
    strcpy(hex,"A52A2A");
  }
  else if (strcmp(colorText,"crimson") == 0) {
    strcpy(hex,"DC143C");
  }
  else if (strcmp(colorText,"cyan") == 0) {
    strcpy(hex,"00FFFF");
  }
  else if (strcmp(colorText,"gold") == 0) {
    strcpy(hex,"FFD700");
  }
  else if (strcmp(colorText,"gray") == 0) {
    strcpy(hex,"808080");
  }
  else if (strcmp(colorText,"grey") == 0) {
    strcpy(hex,"808080");
  }
  else if (strcmp(colorText,"green") == 0) {
    strcpy(hex,"00FF00");
  }
  else if (strcmp(colorText,"indigo") == 0) {
    strcpy(hex,"4B0082");
  }
  else if (strcmp(colorText,"ivory") == 0) {
    strcpy(hex,"FFFFF0");
  }
  else if (strcmp(colorText,"khaki") == 0) {
    strcpy(hex,"F0E68C");
  }
  else if (strcmp(colorText,"limegreen") == 0) {
    strcpy(hex,"32CD32");
  }
  else if (strcmp(colorText,"maroon") == 0) {
    strcpy(hex,"800000");
  }
  else if (strcmp(colorText,"magenta") == 0) {
    strcpy(hex,"FF00FF");
  }
  else if (strcmp(colorText,"navy") == 0) {
    strcpy(hex,"000080");
  }
  else if (strcmp(colorText,"orange") == 0) {
    strcpy(hex,"FFA500");
  }
  else if (strcmp(colorText,"pink") == 0) {
    strcpy(hex,"FFC0CB");
  }
  else if (strcmp(colorText,"purple") == 0) {
    strcpy(hex,"800080");
  }
  else if (strcmp(colorText,"red") == 0) {
    strcpy(hex,"FF0000");
  }
  else if (strcmp(colorText,"silver") == 0) {
    strcpy(hex,"C0C0C0");
  }
  else if (strcmp(colorText,"skyblue") == 0) {
    strcpy(hex,"87CEEB");
  }
  else if (strcmp(colorText,"violet") == 0) {
    strcpy(hex,"EE82EE");
  }
  else if (strcmp(colorText,"white") == 0) {
    strcpy(hex,"FFFFFF");
  }
  else if (strcmp(colorText,"yellow") == 0) {
    strcpy(hex,"FFFF00");
  }
 
  else {
    strcpy(hex,"ZZZZZZ");
  }  //if the color isn't listed, throw an error
 
  memset(colorText,0,20);  
  strcpy(colorText,hex);       //pass the hex value back into colorText
  return;
}
 
 
 
Lab2 - diffuser housing
Lab2 - diffuser colors
Lab2 - arduino board
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