Blink an Arduino LED without writing code
Use an Arduino Uno R3, a USB data cable, and four visual blocks to turn the built-in LED on and off. Follow the steps or simulate it before connecting a board.
No code needed
Add LED on pin 13, Wait 1 second, LED off, and Wait 1 second. This creates one blink cycle. Wrap these four blocks in a Loop when you want it to repeat.
Uses the on-board LED
The Arduino Uno R3 has a built-in LED connected to pin 13. You can follow this tutorial with the board and a USB data cable, without a breadboard or external LED.
A sequence you can keep building on
Change the timing, add a loop, or follow the component guides to connect an external LED and a button. The same project can move from the simulator to a supported physical board.
Step by step
- 1
Create a project
Sign in to ArduinoStudio and create a project from the dashboard. Add a sequence to the canvas. You can explore the live demo first if you want to see a working project before signing in.
- 2
Add a Standard LED block
Click + on the sequence, open LED in the Components tab and pick Standard. Set Digital pin to 13 (the Uno has an LED soldered to pin 13) and Off/On to On.
- 3
Add a Wait block
Click + again, pick Wait from Actions, set Time to 1000 ms. This keeps the LED lit for one second.
- 4
Add LED off + one more Wait
Another Standard LED on pin 13 with Off/On set to Off, then another 1000 ms Wait. That is a full blink cycle.
- 5
Connect your Arduino Uno R3
Use a USB data cable and open the project in desktop Chrome or Edge. Click USB direct in the toolbar, then Connect and select the board in the browser dialog. If needed, follow the firmware setup wizard. Uploading this firmware replaces the sketch already on the board.
- 6
Press Play and adjust the timing
Select your sequence and press Play for one blink cycle. Change both Wait blocks to 2000 ms for a slower blink or 500 ms for a faster one. To repeat a fixed number of times, put the four blocks inside a Loop.
- 7
No board? Press Play anyway
With no board connected, Play runs the same sequence on the simulator’s Virtual Board — you can finish this whole tutorial before the hardware arrives.
See it run
The editor is the real product — this opens the live demo on a working project. No account, nothing to install.
See it run — no account neededQuick answers
What do I need?
For the physical project, use an Arduino Uno R3, a USB data cable, and Chrome or Edge on a computer with permission to access serial devices. Sign in to create and save your project. The simulator lets you practice the sequence without a board.
Do I have to install the Arduino IDE first?
For an Uno R3 with the supported browser setup, the app can upload its Firmata firmware through the connect wizard. You do not need the Arduino IDE for this tutorial. A board using a different bootloader or USB adapter may need additional setup.
Why pin 13?
The Arduino Uno has a tiny LED soldered to pin 13 on the board itself. Sending HIGH to pin 13 lights that LED. No external parts required for the first blink.
What happens after the blink?
Change both Wait values to 2000 ms for a slower blink or 500 ms for a faster blink. Then try the external LED, button, or photoresistor guide to make a project that responds to an input.