Arduino boards come with a little utility: the built-in LED.
It is identified by the letter L
next to it. On the Arduino Uno, it is near pin #13:
On the Arduino MKR 1010 WiFi it is near the 5V output pin:
This LED is connected to the digital I/O pin #13 in most boards. In some boards, like the Arduino MKR series, it’s linked to the pin #6.
In any case you can reference the exact pin using the LED_BUILTIN
constant, that is always correctly mapped by the Arduino IDE to the correct pin, depending on the board you are compiling for.
To light up the LED, first you need to set the pin to be an output in setup()
:
pinMode(LED_BUILTIN, OUTPUT);
Then you can send it a HIGH
signal:
digitalWrite(LED_BUILTIN, HIGH);
or
digitalWrite(LED_BUILTIN, 1);
Here is a simple program that makes the built-in LED blink every second:
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
delay(1000);
}
More electronics tutorials:
- Arduino vs Raspberry Pi
- An introduction to Arduino
- The Arduino Uno rev 3 board
- The Arduino Uno WiFi rev 2 board
- Introduction to the Arduino Programming Language
- Milli Micro Nano Pico
- The Arduino MKR WiFi 1010
- Introduction to Electronics
- Electronics Basics: Analog vs digital
- Electronics Basics: Current
- Electronics Basics: Voltage
- Electronics Basics: Vcc, ground, ...
- Electronics Basics: Resistance
- Electronics Basics: Short Circuit
- Electronics Basics: Your first circuit
- Electronics Basics: Prototyping using breadboards
- Electronics Basics: using a multimeter
- Measuring voltage, current and resistance using a multimeter
- What to buy to get started with Arduino and Electronics
- Arduino project: blink a LED
- The Arduino built-in LED
- Breadboard Power Supply Module
- The Arduino Create Platform
- How to connect to a WiFi network using an Arduino
- How to run a Web Server on an Arduino