I got bored and needed something mesmerizing to look at. These offer some decent ambient lighting for my desk. Code and details after the jump.
I modified this excellent code by Ed Halley to run two LEDs instead of one. Very simple project that took only a few minutes.
/*
* Cycles a three-LED common-anode package through the rainbow.
*
* Demonstrates fading multiple outputs, common-anode wiring, and the
* use of functions to repeat similar tasks.
*
* Often, individual LEDs are wired in an “active high” configuration, so
* a LOW output will cause the LED to turn off, and a HIGH output will
* allow current to flow through the lamp. Sometimes, packages of LEDs
* will have a single ground pin for all of the diodes, called a “common
* cathode.” These work on this same HIGH=ON, LOW=OFF principle. You
* just have to connect all of the positive legs of the diodes to their
* respective output pins, and the common cathode goes to the ground.
*
* Other packages use the opposite wiring plan, offering a “common
* anode.” You have to wire the shared pin to the +VDC source, and put
* the resistors and diodes below the source. To light the lamp, you set
* the output LOW, and to extinguish the lamp, you set the output HIGH.
* Signals which do useful things when given a low value are sometimes
* called “active low.”
*
* Wire a common-anode RGB LED package such that the anode connects to
* the Arduino’s +5V pin, and the other pins go to three PWM outputs to
* allow for fading: digital output pins 3, 5 and 6. Don’t forget to
* put a resistor in series with every LED, or you’ll burn it out!
*
* Ed Halley <ed@halley.cc>
*/// Select which PWM-capable pins are to be used.
int redPin = 5;
int greenPin = 6;
int bluePin = 3;
int redPin2 = 9;
int greenPin2 = 10;
int bluePin2 = 11;// A function to fade UP an active-low or common-anode output.
// Optionally, specify a short delay value to slow the loop.
// (This would fade down an LED that was active high.)
//
void fadeUp(int pin, int d = 10)
{
int i;
for (i = 255; i >= 0; i–)
{
analogWrite(pin, i);
delay(d);
}
}// A function to fade DOWN an active-low or common-anode output.
// Optionally, specify a short delay value to slow the loop.
// (This would fade up an LED that was active high.)
//
void fadeDown(int pin, int d = 10)
{
int i;
for (i = 0; i <= 255; i++)
{
analogWrite(pin, i);
delay(d);
}
}// Set up our outputs, and give full high values so the
// LEDs start off. Then fade in the blue LED.
//
void setup()
{
pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
pinMode(redPin2, OUTPUT);
pinMode(greenPin2, OUTPUT);
pinMode(bluePin2, OUTPUT);analogWrite(redPin, 255);
analogWrite(greenPin, 255);
analogWrite(bluePin, 255);
analogWrite(redPin2, 255);
analogWrite(greenPin2, 255);
analogWrite(bluePin2, 255);fadeUp(bluePin);
fadeUp(redPin2);}
// The cycle of ramps will go through all of the primary
// and secondary hues in the RGB rainbow, and repeat.
//
void loop()
{
fadeUp(greenPin);
fadeUp(greenPin2);
fadeDown(bluePin);
fadeDown(redPin2);
fadeUp(redPin);
fadeUp(bluePin2);
fadeDown(greenPin);
fadeDown(greenPin2);
fadeUp(bluePin);
fadeUp(redPin2);
fadeDown(redPin);
fadeDown(bluePin2);
}
