/*
 MultipleLEDsPushButton
 Cycle through three LEDs with a pushnutton
 */

const int pushButtonPin = 2;  // connect the push button to digital pin 2
const int led0 = 13;          // connect an LED to pin 13
const int led1 = 12;          // connect an LED to pin 12
const int led2 = 11;          // connect an LED to pin 11

const int debounceTime = 5;     // number of millisecods to delay after button press

int ledState;                   // used to decide which LED is on (0 to 2)
boolean lastButtonState = HIGH; // value of buttonState from previous loop iteration
boolean buttonState = HIGH;     // start by assuming button is unpressed

boolean debounce(int pinNum) {
  delay(debounceTime);
  return digitalRead(pinNum);
}

void setup() {
  pinMode(pushButtonPin, INPUT);      // make the pushbutton's pin an input
  digitalWrite(pushButtonPin, HIGH);  // turn on pullup resistors

  // make LED pins outputs
  pinMode(led0, OUTPUT);          
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);

  // initialize state
  ledState = 0;
  
  // turn the correct LED on and the others off
  digitalWrite(led0, HIGH);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
}

void loop() {
  buttonState = debounce(pushButtonPin);  // read the input pin

  // if button goes down and previously it was high...
  if (buttonState == LOW && lastButtonState == HIGH) {
    ledState = (ledState + 1) % 3;    // cycle through 0,1,2
  }

  // turn the correct LED on and the others off  
  if (ledState == 0)
  {
    digitalWrite(led0, HIGH);  
    digitalWrite(led1, LOW);  
    digitalWrite(led2, LOW);  
  }
  else if (ledState == 1)
  {
    digitalWrite(led0, LOW);  
    digitalWrite(led1, HIGH);  
    digitalWrite(led2, LOW);  
  }
  else if (ledState == 2)
  {
    digitalWrite(led0, LOW);  
    digitalWrite(led1, LOW);  
    digitalWrite(led2, HIGH);  
  }
  else // turn all LEDs on to indicate an error state.
  {
    digitalWrite(led0, HIGH);  
    digitalWrite(led1, HIGH);  
    digitalWrite(led2, HIGH);  
  }
  
  lastButtonState = buttonState;
}