Lab 2: Diffuser & Different Digital I/O with Arduino

 
Description
For this week's lab we had to choose a good diffuser for our RGB LEDs. My winner was a Tide wash bag that gave an almost omogenous effect of color. I uploaded a video with the result on youtube (http://www.youtube.com/watch?v=GhfzUGG6OrQ).
We then had to change the code to control the RGB values with multiple key presses. In my code, I asked the user to give me a string of "r", "g" and "b" and changed the brightness of each led accordingly. 0 "r"s turned off the red led whereas 10 "r"s turned it fully on (r value 255).
 
Components
1 Arduino Uno
1 Breadboard
3 leds
1 220 Ohm resistor
cables
 
Code
 

/* 

 * Serial RGB counting

 * ---------------

 * Serial commands control the brightness of R,G,B LEDs 

 *

 * Command structure is "string", where "string" is a text input from the user

 * Code counts the number of "r","g" or "b" in the string. "colorVal" is a number 0 to 255.

 * E.g. "rrrbbbbb"   turns the red LED to 30%, turns the green LED off and the blue LED on to 50%.  

 *

 * Created 24 September 2013

 */

char serInString[100];  // array that will hold the different bytes of the string. 100=100characters;

                        // -> you must state how long the array will be else it won't work properly

char colorCode;

int colorValr,colorValg,colorValb,r,g,b,n;

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

void setup() {

  pinMode(redPin,   OUTPUT);   // sets the pins as output

  pinMode(greenPin, OUTPUT);   

  pinMode(bluePin,  OUTPUT);

  Serial.begin(9600);

  analogWrite(redPin,   0);   // set them all to mid brightness

  analogWrite(greenPin, 0);   // set them all to mid brightness

  analogWrite(bluePin,  0);   // set them all to mid brightness

  Serial.println("Change the brightness (from 0-10) of the led typing r,g,b multiple times.");  

}

void loop () {

//Turn off the leds.

  r=0; g=0; b=0;

  // clear the string

  memset(serInString, 0, 100);

  //read the serial port and create a string out of what you read

  readSerialString(serInString);

  n=0;

  colorCode = serInString[0];

  while( colorCode != '\0' ) {

//as long as there is a string look for rgb characters

    if (colorCode == 'r')

      r++;

    else if  (colorCode == 'g')

      g++;

    else if  (colorCode == 'b')

      b++;   

    serInString[n] = 0;       // indicates we've used this string  

    n++;

    colorCode = serInString[n];

  }     

//output the value with brightness from 0-10

  colorValr =  floor(r*2.55);

  colorValg =  floor(g*2.55);

  colorValb =  floor(b*2.55);  

  analogWrite(redPin, colorValr);

  analogWrite(greenPin, colorValg);

  analogWrite(bluePin, colorValb);

  while (!Serial.available()) {

      delay(500); // wait a bit, for serial data

  }

}

//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++;

  }

}