Blink An LED Using Arduino

This example shows the simplest thing you can do with an Arduino to see physical output: it blinks an LED.

Circuit

To build the circuit, connect one end of the resistor to Arduino pin 13. Connect the long leg of the LED (the positive leg, called the anode) to the other end of the resistor. Connect the short leg of the LED (the negative leg, called the cathode) to the Arduino GND, as shown in the diagram and the schematic below.

Most Arduino boards already have an LED attached to pin 13 on the board itself. If you run this example with no hardware attached, you should see that LED blink.

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Schematic

After you build the circuit plug your Arduino board into your computer, start the Arduino IDE, and enter the code below.

Code

In the program below, the first thing you do is to initialize pin 13 as an output pin with the line

pinMode(13, OUTPUT);

In the main loop, you turn the LED on with the line:

digitalWrite(13, HIGH);

This supplies 5 volts to pin 13. That creates a voltage difference across the pins of the LED, and lights it up. Then you turn it off with the line:

digitalWrite(13, LOW);

 

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