Why does this yellow light keep blinking?

This yellow light on my labeled "L"  i/o board is constantly blinking. And I keep trying to upload "blink" but it doesn't reset and it also makes the LED blink in that pattern to.

Comments

[wandersen]

change blink as follows to turn t off:

Not all of blink code:

...
// constants won't change. Used here to
// set pin numbers:
const int led13 = 13;
const int ledPin = 12; // 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)

void setup() {
// set the digital pin as output:
pinMode(ledPin, OUTPUT);
pinMode(led13, OUTPUT);
}
int ledLow = LOW ;
int ledHigh = HIGH ;

void loop()
{
digitalWrite( led13, ledLow) ;
...

[wandersen]

The yellow led on you Ardruino UNO board marked with L is port 13.

[transuranic]

randomly blinking along with "L"

[frollard]

....the blink example code causes the io light to flash...
...uploading code causes the led to flash also...

what EXACTLY is it doing? flickering quickly, or flashing at a 1 second interval?