Data Sheet

15
Lessons
Lesson 1 Blink and Breathing LED
Overview
In this project, you will learn the simplest thing you can do with an Arduino and see physical
world by blinking the on-board LED and without doing any programming.
Second step, you will learn how to use the PWM square-wave signal to control the external
LED as a breathing lamp which gradually becomes brighter and then gradually becomes dark.
Components required
Name Qty Name Qty
UNO R3 or MEGA 2560 1 220Ω Resistor 1
5mm Red LED 1 DuPont Wire 2
Component Introduction
The UNO R3 board has rows of connectors along both sides that are used to connect to
different electronic devices and plug-in 'shields' that extends its capability.
It also has a single LED that you can control from your sketches. This LED is built onto the
UNO R3 board and is often referred to as the 'L' LED as this is how it is labeled on the board.
You may find that your UNO R3 board's 'L' LED already blinks when you connect it to a USB
plug. This is because the boards are generally shipped with the 'Blink' sketch pre-installed.
Since the first experiment of blinking onboard LED is quite so easy without any programming,
it just gives you an idea about how electronic device works. The next step we will try something
interesting and more complex by connecting a breadboard and external LED to build a
breathing lamp.
Breadboard is just a grid of holes in a plastic block. Inside are
strips of metal that provide electrical connection between holes
in the shorter rows. Pushing the legs of two different
components into the same row joins them together electrically.
LED is the abbreviation of light emitting diode. The LED has two electrodes, a positive
electrode and a negative electrode, it will light only when a forward current passes. Generally,
the drive current for LED is 5-20mA. Therefore, it needs an extra resistor for current limitation