Let's learn how to blink an LED using Arduino’s
digital output.
If you’re new to Arduino, this is a great
place to start.
You can follow along virtually using Tinkercad
Circuits, then afterward grab your Arduino
Uno board and a USB cable to create a physical
circuit.
Take a look at the circuit in the workplane.
Click Start Simulation to watch the LED blink.
You can use the simulator at any time to test
your circuits.
The LED’s legs are connected to two pins
on the Arduino: ground and pin 13.
This component between the LED and pin 13
is a resistor, which helps limit the current
to prevent the LED from burning itself out.
Without it, you’ll get a warning that the
LED might burn out soon.
It doesn’t matter whether the resistor comes
before or after the LED in the circuit, or
which way around it goes. The colored stripes
indicate the resistor’s value, and for this
circuit, anywhere from 100 ohms to 1000 ohms
will work great. Click once to connect a wire
to a component or pin, and click again to
connect the other end.
The LED, unlike the resistor, is polarized,
which means it only works when the legs are
connected a certain way. The positive leg,
called the anode, usually has a longer leg,
and is wired to power, in this case coming
from your Arduino’s output pin 13. The negative
leg, called the cathode, with its shorter
leg, connects to ground.
Did you notice the small LED flashing on the
board itself? This built-in LED is also connected
to pin 13, and is meant to be used for testing
purposes without the need to connect any external
components. It even has its own tiny resistor,
soldered directly to the surface of the Arduino
board.
Let’s look at the simple code controlling
the blink by checking out the code blocks
editor.
The code starts out with two gray comment
blocks, which are just notes for us humans
to read.
The first blue output block sets the built-in
LED HIGH, which is Arduino’s way of describing
“on.” This output command will activate
a 5V signal to connect anything connected
to the specified pin.
Next up is a a yellow command block that waits
for one second, simple enough. So the program
will pause while the LED is on for one second.
Next, after another comment is a blue output
block to set the LED back to LOW, or “off,”
followed by another second-long pause.
Try customizing this code by changing the
wait times, and clicking Start Simulation.
You can even add more output and wait blocks
to create longer flashing patterns.
In the text editor, you can see the Arduino
code generated by the code blocks. All the
extra symbols are part of Arduino’s syntax,
but don’t get intimidated. It takes time
to learn to write proper code from scratch!
I’ll break it down for you here and you
can always use the blocks for reference as
you level up.
This first section is title block comment,
followed by the code’s setup, which helps
set up things your program will need later.
It runs once when the program starts up. Our
blink sketch’s setup configures pin 13 as
an output, which prepares the board to send
signals to it, rather than listen.
The main body of the program is inside the
loop. This part of the code will execute on
repeat, so long as the board has power. The
colored text following double slashes are
also comments to help make the program easier
to understand.
The output command we’re using is called
digitalWrite(), which is a function that sets
a pin HIGH or LOW, on or off.
To pause the program we’ll use delay(),
which takes a number of milliseconds. One
second is 1000 milliseconds.
Try it for yourself in Tinkercad Circuits!
Grab this circuit and code combo any time
using the Starter available in the components
panel.
To program your physical Arduino Uno, copy
the code from the window and paste it into
an empty Arduino sketch, or click the Download
Code button and open the resulting file using
your Arduino software.
Plug in your USB cable and select your board
in the tools menu. Upload the code and watch
your onboard LED flash with the custom blink
you created earlier!
Now that you know how to blink an LED using
Arduino’s digital output, you're ready to
try other Arduino exercises that utilize the
digitalWrite() function. Try using a breadboard
to add more LEDs and code to control them
in the next lesson.
Thanks for watching and learning how to blink
an LED with Arduino and Tinkercad Circuits.
Check out the rest of our huge collection
of interactive beginner electronics tutorials,
and even build circuits into your 3D designs.
See you next time!
