/*
 * LedBrightness sketch
 * controls the brightness of LEDs on analog output ports
*/
const int firstLed = 3; // specify the pin for each of the LEDs
const int secondLed = 5;
const int thirdLed = 6;
int brightness = 0;
int increment = 1;
void setup()
{
 // pins driven by analogWrite do not need to be declared as outputs
}
void loop()
{
 if(brightness > 255)
 {
increment = -1; // count down after reaching 255
 }
 else if(brightness < 1)
 {
 increment = 1; // count up after dropping back down to 0
 }
 brightness = brightness + increment; // increment (or decrement sign is minus)
 // write the brightness value to the LEDs
 analogWrite(firstLed, brightness);
 analogWrite(secondLed, brightness);
 analogWrite(thirdLed, brightness );
 delay(10); // 10ms for each step change means 2.55 secs to fade up or down
}