Real LED Blink - Device Heartbeat

I just created a heartbeat for my standalone Arduino based hardware.
The code (based on this example) can blink a LED givin a better sense of heartbeat (instead flashing). In addition runs without utilizing the delay function.

Its a noob solution but it may be useful for some users.

/* Heartbeat
 Based on example BlinkWithoutDelay http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
 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.
 
 Created JAN 2011
 by Nikos Georgousis
 
 Original code authors
 created 2005
 by David A. Mellis
 modified 8 Feb 2010
 by Paul Stoffregen
 */

// constants won't change. Used here to 
// set pin numbers:
const int ledPin =  13;      // the number of the LED pin

// Variables will change:
int ledState = LOW;             // ledState used to set the LED
long previousMillis = 0;        // will store last time LED was updated
// the follow variables is a long because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long interval = 1000;           // interval at which to blink (milliseconds)
long interval2 = 50;            // this second interval variable is for light duration
void setup() {
  // set the digital pin as output:
  pinMode(ledPin, OUTPUT);      
}

void loop()
{

  if (ledState == LOW) // if the led is OFF then check if its time to blink it 
  { 
       unsigned long currentMillis = millis();
    if(currentMillis - previousMillis > interval) {
      // save the last time you blinked the LED 
      previousMillis = currentMillis;   
      ledState = HIGH;
      // set the LED with the ledState of the variable:
      digitalWrite(ledPin, ledState);
    }
  }
  else // if the led is ON wait just a shorter period of time (interval2) and turn it OFF
  {
     unsigned long currentMillis = millis();
    if(currentMillis - previousMillis > interval2) {
      // save the last time you blinked the LED 
      previousMillis = currentMillis;   
        ledState = LOW;
      // set the LED with the ledState of the variable:
      digitalWrite(ledPin, ledState);
    }
  }
}

Cheers

Nice. We all begin somewhere and progress.

All your milli-stuff should use [b]unsigned long[/b], not just long. millis() is unsigned long.