Summary of Blink LED using Arduino
This article explains a basic Arduino project to blink an LED. It involves connecting a 220-ohm resistor to pin 13 of the Arduino, then attaching the LED (anode to resistor, cathode to ground). The Arduino code sets pin 13 as output, turning the LED on and off with one-second delays to make the blinking visible. Many Arduino boards include a built-in LED on pin 13, so external LEDs are optional. This simple project introduces digital output control and timing with the Arduino.
Parts used in the Blink LED project:
- Arduino Board
- LED
- 220-ohm resistor
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, attach a 220-ohm resistor to pin 13. Then attach the long leg of an LED (the positive leg, called the anode) to the resistor. Attach the short leg (the negative leg, called the cathode) to ground. Then plug your Arduino board into your computer, start the Arduino program, and enter the code 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
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);
That takes pin 13 back to 0 volts, and turns the LED off. In between the on and the off, you want enough time for a person to see the change, so the delay() commands tell the Arduino to do nothing for 1000 milliseconds, or one second. When you use the delay() command, nothing else happens for that amount of time. Once you’ve understood the basic examples, check out the BlinkWithoutDelay example to learn how to create a delay while doing other things.
Hardware Required
- Arduino Board
- LED
For more detail: Blink LED using Arduino
