No Voltage at Pins - Arduino Uno

Using Arduino LEDs and Multiplexing
#1

Hi,
I'm an arduino beginner and I have a problem with lighting up a led.

I connected the led with the + side to Pin 13 and the - side to ground of the arduino.

If I connect the 3,3 v to the led instead of the Pin 13, the led working.

#define LEDPIN 13

void setup() {
  pinMode(LEDPIN, OUTPUT);
}

void loop() {
    digitalWrite(LEDPIN, HIGH); 
}

So whats wrong?
Thanks.

#2

Also tried the example

int ledPin = 12;                 // LED connected to digital pin 13

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  digitalWrite(ledPin, HIGH);   // sets the LED on
  delay(1000);                  // waits for a second
  digitalWrite(ledPin, LOW);    // sets the LED off
  delay(1000);                  // waits for a second
}

same result, no voltage

#3

It's working now. Maybe a cable was broken. :confused:

#4

mranguish:
I connected the led with the + side to Pin 13 and the - side to ground of the arduino.

You should never run a LED without a current limiting resistor directly from the Arduino pins.
You will damage the LED and the Arduino.

#5