/*
 MultipleLEDsTimer
 Cycle through three LEDs with a timer.
 */

const int delayTime = 500;  // time to wait between LED changes
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

int ledState;               // used to decide which LED is on (0 to 2)

void setup() {
  // 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() {
  delay(delayTime);
  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);  
  }
}