/* Variable Brightness LEDs 2
*  Done with three of Arduino's Pulse Width Modulation (PWM)
*  pins (9,10,11)
*  This time we'll use a direction changing variable to
*  change whether the pwmVal's will go up or down in the Loop
*/

// Set three pin variables for the three PWM pins
int pwmPin1 = 11;
int pwmPin2 = 10;
int pwmPin3 = 9;
// Set a variable for the intial value for the PWM
int pwmVal1 = 0;
int pwmVal2 = 0;
int pwmVal3 = 0;
// Set a variable for the inital direction (increment or decrement) for the PWM
// A value of 1 will increment pwmVal's and a value of -1 will decrement pwmVal's.
int upDown1 = 1;
int upDown2 = 1;
int upDown3 = 1;

// Setup
// Set PWM's to OUTPUT
void setup() 
{
  pinMode(pwmPin1, OUTPUT);
  pinMode(pwmPin2, OUTPUT);
  pinMode(pwmPin3, OUTPUT);
}

//Loop
void loop() 
{
  // analogWrite's range runs from 0 to 255, so when any of 
  // our values reaches maximum, instead of reseting it to 0
  // we'll change the variable upDown to -1. This will cause
  // pwmVal's to get smaller instead of bigger.
  if(pwmVal1 >= 255) {
    upDown1 = -1;
  }
  // Conversely, when it reaches a minimum (0), set the upDown to 1.
  // This will cause pwmVal's to get bigger instead of smaller.
  if(pwmVal1 <= 0) {
    upDown1 = 1;
  }
  // Same process for all pwmVal's (pwmVal2, pwmVal3)
  if(pwmVal2 >= 255) {
    upDown2 = -1;
  }
  if(pwmVal2 <= 0) {
    upDown2 = 1;
  }
  if(pwmVal3 >= 255) {
    upDown3 = -1;
  }
  if(pwmVal3 <= 0) {
    upDown3 = 1;
  }
  // Now set the pwmPins...
  analogWrite(pwmPin1,pwmVal1);
  // ... and depending on whether upDown is 1 or -1, increment
  // or decrement pwmVal's 
  pwmVal1 = pwmVal1 + (1 * upDown1);
  analogWrite(pwmPin2,pwmVal2);
  pwmVal2 = pwmVal2 + (5 * upDown2);
  analogWrite(pwmPin3,pwmVal3);
  pwmVal3 = pwmVal3 + (10 * upDown3);
  // Delay a bit before looping
  delay(10);
}