The Arduino Uno has a built-in LED connected to digital pin 13. In this project, we write a basic sketch to turn the LED on and off every second using digitalWrite () and delay ().

Arduino_led_blink Blinking the led on Arduino Uno and observing the rate of speed for different delay values.

This is tutorial number 1 from our series of Arduino tutorials and in this part I will talk about blinking an LED using the one already available on the Arduino Uno board or using an external LED to ...

For the first sketch, let's blink an LED and then extend it to blink multiple LEDs alternately. Before the software part, let's first set up the circuit to connect the LED to the Arduino.

Once the code is uploaded to the BlinkM, you essentially have a micro Arduino running at 8MHz with a built in LED and 2 I/O lines (5 if you snip off the LED).