import processing.serial.*;

float redValue = 0;        // red value
float greenValue = 0;      // green value
float blueValue = 0;       // blue value

Serial myPort;

void setup() {

size(200, 200);

// List all the available serial ports
println(Serial.list()[0]);
// I know that the first port in the serial list on my mac
// is always my  Arduino, so I open Serial.list()[0].
// Open whatever port is the one you’re using.
myPort = new Serial(this, Serial.list()[0], 9600);

// don’t generate a serialEvent() unless you get a newline character:
myPort.bufferUntil(‘\n’);
}

void draw() {
// set the background color with the color values:
background(redValue, greenValue, blueValue);
}

void serialEvent(Serial myPort) {
// get the ASCII string:
String inString = myPort.readStringUntil(‘\n’);

if (inString != null) {
// trim off any whitespace:
inString = trim(inString);
// split the string on the commas and convert the
// resulting substrings into an integer array:
float[] colors = float(split(inString, “,”));
// if the array has at least three elements, you know
// you got the whole thing.  Put the numbers in the
// color variables:
if (colors.length >=3) {
// map them to the range 0-255:
redValue = map(colors[0], 0, 1023, 0, 255);
greenValue = map(colors[1], 0, 1023, 0, 255);
blueValue = map(colors[2], 0, 1023, 0, 255);
}
}
}