/*
Changing duty cycle of PWM LED with a button. 
This was adapted from: http://www.arduino.cc/en/Tutorial/Debounce
 */

// constants won't change. They're used here to 
// set pin numbers:
const int buttonPin = 3;     // the number of the pushbutton pin
const int ledPin =  7;      // the number of the LED pin

// Variables will change:
int buttonState;             // the current reading from the input pin
int lastButtonState = LOW;   // the previous reading from the input pin
int toggle = 0;
int buttonPressed;

long lastDebounceTime = 0;  // the last time the output pin was toggled
long debounceDelay = 50;    // the debounce time; increase if the output flickers

void setup() {
  pinMode(buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

//duty cycles that we will have
float duty[] = {0.,.1,.2,.4,1.0};
int which_duty = 0;
int period = 10; //ms

void loop() {
  digitalWrite(ledPin, HIGH); 
  delay(duty[which_duty]*period); 

  digitalWrite(ledPin, LOW);     
  delay((1-duty[which_duty])*period);

  //check out the button to see if we need to switch duty cycle.
  buttonPressed = 0;
  int reading = digitalRead(buttonPin);
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  } 
  
  if ((millis() - lastDebounceTime) > debounceDelay) {
    buttonState = reading;
  } 
  if(toggle == 0 && buttonState == 1){
    which_duty = (which_duty+1) % 5;
    toggle = 1; 
  }
  if(toggle == 1 && buttonState == 0){
     toggle = 0; 
  }
  lastButtonState = reading;
}