Description

I used an Arduino to control three LED’s: red, green, and blue. With pulse width modification, I control the brightness of each. They are all under a plastic container that has been covered with a couple layers of bubble wrap to act as a diffuser. The brightness of each can be controlled by using serial communication sending combinations of the letters “r”, “g”, and “b”. For example, “rrrrrbbbb” will result in a purple light.

Components

• Arduino
• 3 LED’s: red, green, blue
• 3 Resistors (220Ω)
• 5 Wires
• 1 Breadboard
• 1 Plastic storage container
• Bubble wrap

Code

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 redVal;
int greenVal;
int blueVal;
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, 127); // set them all to mid brightness
analogWrite(greenPin, 127); // set them all to mid brightness
analogWrite(bluePin, 127); // set them all to mid brightness
Serial.println("enter color command using r's, b's, and g's (e.g. 'rrrrrrggggg') :");
}
void loop () {
// clear the string
memset(serInString, 0, 100);
//read the serial port and create a string out of what you read
readSerialString(serInString);
// initialize all back to zero for each loop
redVal = 0;
greenVal = 0;
blueVal = 0;
colorCode = serInString[0];
if( colorCode == 'r' || colorCode == 'g' || colorCode == 'b' ) {
// increment each color based on number of each letter
for (int i = 0; i < strlen(serInString); i++) { switch(serInString[i]) { case 'r': redVal += 25; break; case 'g': greenVal += 25; break; case 'b': blueVal += 25; break; } } Serial.print("Setting color "); Serial.println(); Serial.print("red to "); Serial.print(redVal); Serial.println(); Serial.print("green to "); Serial.print(greenVal); Serial.println(); Serial.print("blue to "); Serial.print(blueVal); Serial.println(); serInString[0] = 0; // indicates we've used this string analogWrite(redPin, redVal); analogWrite(greenPin, greenVal); analogWrite(bluePin, blueVal); } delay(100); // 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++; } }