Notes

/* Blink without Delay

Turns on and off a light emitting diode (LED) connected to a digital
pin, without using the delay() function. This means that other code
can run at the same time without being interrupted by the LED code.

The circuit:
* LED attached from pin 13 to ground.
* Note: on most Arduinos, there is already an LED on the board
that's attached to pin 13, so no hardware is needed for this example.

created 2005
by David A. Mellis
modified 8 Feb 2010
by Paul Stoffregen
modified 11 Nov 2013
by Scott Fitzgerald


This example code is in the public domain.

http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
*/

// constants won't change. Used here to set a pin number :
const int ledPin = 13; // the number of the LED pin
const int buttonPin = 8;
const int buttonPin2 = 7;

// Variables will change :
bool ledState = LOW; // ledState used to set the LED
bool buttonState = LOW;
bool buttonState2 = LOW;

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0; // will store last time LED was updated

// constants won't change :
long interval = 1000; // interval at which to blink (milliseconds)

void setup() {
// set the digital pin as output:
pinMode(ledPin, OUTPUT);
pinMode(buttonPin, INPUT);
pinMode(buttonPin2, INPUT);
}

void loop() {
// here is where you'd put code that needs to be running all the time.

// check to see if it's time to blink the LED; that is, if the
// difference between the current time and last time you blinked
// the LED is bigger than the interval at which you want to
// blink the LED.
buttonState = digitalRead(buttonPin);
buttonState2 = digitalRead(buttonPin2);
unsigned long currentMillis = millis();

if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;

// if the LED is off turn it on and vice-versa:
if (buttonState == buttonState2) {
digitalWrite(13, LOW);
} else {
if(buttonState == HIGH){
digitalWrite(13, HIGH);
if(buttonState2 == HIGH){
interval = 2000;
digitalWrite(13, HIGH);
}
}
}
}
}