Lab 2 - PWM & Diffuser

Description

Serial commands to control the brightness of LEDs. Using a diffuser to create new colors. Reading string inputs to control LEDs.

Components Used

3 - 220 ohm resistors, 3 LEDs (red, green, blue), wiring, light bulb for the diffuser.

Code 1 - takes rrrr, rrbb as input and adjusts appropriate LEDs.

 /* 
 * Serial RGB LED
 * ---------------
 * Serial commands control the brightness of R,G,B LEDs 
 *
 * Command structure is "<colorCode><colorVal>", where "colorCode" is
 * one of "r","g",or "b" and "colorVal" is a number 0 to 255.
 * E.g. "r0"   turns the red LED off.  
 *      "g127" turns the green LED to half brightness
 *      "b64"  turns the blue LED to 1/4 brightness
 *
 * Alternate command structure is "<colorCode>*", where "colorCode" is
 * one of "r","g", or "b".
 * E.g. "r"    increases the red LED brightness by 10
 *      "rrr"  increases the red LED brightness by 30
 *      "ggb"  increases the green LED brightness by 20 and the blue by 10
 *
 * Created 18 October 2006
 * copyleft 2006 Tod E. Kurt <tod@todbot.com
 * http://todbot.com/
 *
 * Adapted 5 September 2007
 * copylefter 2007 Ryan Aipperspach <ryanaip@alumni.rice.edu>
 *
 */
 
//include support for manipulating strings.
#include <stdio.h>
#include <string.h>

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 colorVal;

int greenPin = 9;  // Green LED, connected to digital pin 9
int redPin   = 10;   // Red LED,   connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11

int redValue = 1;
int greenValue = 1;
int blueValue = 1;

void setup() {
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT);
  Serial.begin(9600);
  analogWrite(redPin,   redValue);   // set them all to mid brightness
  analogWrite(greenPin, greenValue);   // set them all to mid brightness
  analogWrite(bluePin,  blueValue);   // set them all to mid brightness
  Serial.println("enter color command (e.g. 'rr or rrrrrrrrbbbb') :");  
}

void loop () {
  //read the serial port and create a string out of what you read
  readSerialString(serInString, 100);
    
  //read commands of the form 'rrrb'
  processRepeatKeyCommands(serInString, 100);
  
  resetSerialString(serInString, 100);  

  delay(100);  // wait a bit, for serial data
}

void resetSerialString (char *strArray, int length) {
  for (int i = 0; i < length; i++) {
    strArray[i] = '\0';
  }
}

//read a string from the serial and store it in an array
//you must supply the array variable
void readSerialString (char *strArray, int maxLength) {
  int i = 0;

  if(!Serial.available()) {
    return;
  }
  while (Serial.available() && i < maxLength) {
    strArray[i] = Serial.read();
    i++;
  }
}

//go through the string, and increase the red value for each 'r',
//the green value for each 'g', and the blue value for each 'b'.
//For example "rrrg" increases red by 30 and green by 10.
void processRepeatKeyCommands(char *strArray, int maxLength) {
  int i = 0;
  
  //loop through the string (strArray)
  //i = the current position in the string
  //Stop when either (a) i reaches the end of the string or
  //                 (b) there is an empty character '\0' in the string
  while (i < maxLength && strArray[i] != '\0') {
    //Read in the character at position i in the string
    colorCode = serInString[i];
    
    //If the character is r (red)...
    if (colorCode == 'r') {
      //Increase the current red value by 10, and if you reach 255 go back to 0
      redValue = (redValue + 10) % 255;
      analogWrite(redPin, redValue);
      Serial.print("setting color r to ");
      Serial.println(redValue);
      
    //If the character is g (green)...
    } else if (colorCode == 'g') {
      greenValue = (greenValue + 10) % 255;
      analogWrite(greenPin, greenValue);
      Serial.print("setting color g to ");
      Serial.println(greenValue);
    
    //If the character is b (blue)...
    } else if (colorCode == 'b') {
      blueValue = (blueValue + 10) % 255;
      analogWrite(bluePin, blueValue);
      Serial.print("setting color b to ");
      Serial.println(blueValue);
    }
    
    //Move on to the next character in the string
    //From here, the code continues executing from the "while" line above...
    i++;
  }
}

Code 2 - takes names of fruits as input, and changes the LEDs to mimic the color of the fruit.

 /* 
 * Serial RGB LED Control
 * Fruit Names control color of LEDs
 *
 * Credit for some portions of this code to:
 * Tod E. Kurt <tod@todbot.com
 * Ryan Aipperspach <ryanaip@alumni.rice.edu>
 *
 */
 
#include <stdio.h>
#include <string.h>

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

// Output
int greenPin = 9;   // Green LED,   connected to digital pin 9
int redPin = 10;  // Red LED, connected to digital pin 10
int bluePin  = 11;  // Blue LED,  connected to digital pin 11

//initial values
int greenValue = 1;
int redValue = 1;
int blueValue = 1;

// Setup
void setup() {
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT);
  Serial.begin(9600);
  analogWrite(redPin, redValue);
  analogWrite(greenPin, greenValue);
  analogWrite(bluePin, blueValue);
  Serial.println("Enter a fruit name! (Limited to apple, banana, blueberry, cherry and melon only) :");  
}

void loop () {
  //read the serial port and create a string out of what you read
  readSerialString(serInString, 100);

  doFruitName(serInString, 100);
  
  resetSerialString(serInString, 100); 
  delay(100);  // wait a bit, for serial data
}

//reset serial string
void resetSerialString (char *strArray, int length) {
  for (int i = 0; i < length; i++) {
    strArray[i] = '\0';
  }
}

//read a string from the serial and store it in an array
void readSerialString (char *strArray, int length) {
  int i = 0;
  if(!Serial.available()) {
    return;
  }
  while (Serial.available() && i < length) {
    strArray[i] = Serial.read();
    i++;
  }
}

//read a string
void doFruitName(char *strArray, int length) {
	if (stringsEqual(strArray, "cherry", 6)) {
		analogWrite(redPin, 255);
		analogWrite(greenPin, 0);
		analogWrite(bluePin, 0);
	}
	else if (stringsEqual(strArray, "apple", 5)) {
		analogWrite(redPin, 0);
		analogWrite(greenPin, 255);
		analogWrite(bluePin, 0);
	}
	else if (stringsEqual(strArray, "blueberry", 9)) {
		analogWrite(redPin, 0);
		analogWrite(greenPin, 0);
		analogWrite(bluePin, 255);
	}
	else if (stringsEqual(strArray, "melon", 5)) {
		analogWrite(redPin, 0);
		analogWrite(greenPin, 255);
		analogWrite(bluePin, 255);
	}
	else if (stringsEqual(strArray, "banana", 6)) {
		analogWrite(redPin, 255);
		analogWrite(greenPin, 20);
		analogWrite(bluePin, 0);
	}	
}

boolean stringsEqual(char *string1, char *string2, int numCharacters) {
	if (strncmp(string1, string2, numCharacters) == 0) {
		return true;
	} 
	else {
		return false;
	}	
}

Images

blue

green