RGB

/*
 * RGB.ino
 * Program to make the color of an RGB LED attached to an Arduino change based on the reading of a potentiometer.
 * Shows how to use RGB LEDs, potentiometers, and switch statements
 * 123D Circuits demo: https://123d.circuits.io/circuits/1543748-the-unnamed-circuit/
 * Codebender: https://codebender.cc/sketch:230656
 * Diagram of color changes: http://i.imgur.com/jDrOQUy.png
 * Schematic: http://i.imgur.com/hTR5oGr.png
 */

int redpin = 11; // setting pin #s for the colors
int greenpin = 10;
int bluepin = 9;
int r, g, b = 0; // these will be used for color values; init to 0 for now
int value;

void setup() {                    // run once, when the sketch starts
	pinMode(redpin, OUTPUT); // set pinmodes
	pinMode(greenpin, OUTPUT);
	pinMode(bluepin, OUTPUT);
	Serial.begin(9600);           // set up Serial library at 9600 bps
}

void loop() {                      // run over and over again
	value = analogRead(A0); //find potentiometer value
	Serial.println(value);
	switch ((value-value%170)/170){ //figures out how many times 170 goes into the value to the nearest whole number, then switches on this number
		//* this part of the code is for a common anode LED; remove the first slash to switch to common cathode
		case 0: // increases red
			r = 255-(value)*3/2; // because 0<value<170, 0<value for color<255 (it is a common anode so the values are reversed)
			g = 255;
			b = 255; // green and blue are not lit up
			break;
		case 1: // increases green
			r = 0;
			g = 255-(value-170)*3/2;
			b = 255;
			break;
		case 2: // increases blue
			r = 0;
			g = 0;
			b = 255-(value-340)*3/2;
			break;
		case 3: // decreases value for red
			r = (value-510)*3/2;
			g = 0;
			b = 0;
			break;
		case 4: // decreases value for green
			r = 255;
			g = (value-680)*3/2;
			b = 0;
			break;
		case 5: // decreases value for blue
			r = 255;
			g = 255;
			b = (value-850)*3/2;
			break;
		default: // since 170 * 6 is 1020, this will usually happen from 1020 to 1024, and it also works fine as a default if something goes wrong
			r = 255; // all colors are turned off
			g = 255;
			b = 255;
			break;
		/*/ this part of the code is for a common cathode LED
		case 0: // increases red
			r = (value)*3/2;
			g = 0;
			b = 0;
			break;
		case 1: // increases green
			r = 255;
			g = (value-170)*3/2;
			b = 0;
			break;
		case 2: // increases blue
			r = 255;
			g = 255;
			b = (value-340)*3/2;
			break;
		case 3: // decreases red
			r = 255-(value-510)*3/2;
			g = 255;
			b = 255;
			break;
		case 4: // decreases greeen
			r = 0;
			g = 255-(value-680)*3/2;
			b = 255;
			break;
		case 5: //decreases blue
			r = 0;
			g = 0;
			b = 255-(value-850)*3/2;
			break;
		default: //all colors are off
			r = 0;
			g = 0;
			b = 0;
			break;
		//*/
	}
	analogWrite(redpin, r); // setting colors to the led
	analogWrite(greenpin, g);
	analogWrite(bluepin, b);
	delay(10); //brief delay
}