LED

Just as printing “Hello, world!” is the first step in learning to program, using a program to drive an LED is the traditional introduction to learning physical programming.

Wiring

Code

Note:

• You can open the file 10-led.ino under the path of Basic-Starter-Kit-for-Arduino-Uno-R4-WiFi-main\10-led.

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Code Analysis

Here, we connect the LED to the digital pin 9, so we need to declare an int variable called ledpin at the beginning of the program and assign a value of 9.

constintledPin=9; Now, initialize the pin in the setup() function, where you need to initialize the pin to OUTPUT mode.

voidsetup()
{
pinMode(ledPin,OUTPUT);
}

In loop(), digitalWrite() is used to provide 5V high level signal for ledpin, which will cause voltage difference between LED pins and light LED up.

digitalWrite(ledPin,HIGH);

If the level signal is changed to LOW, the ledPin’s signal will be returned to 0 V to turn LED off.

digitalWrite(ledPin,LOW);

An interval between on and off is required to allow people to see the change, so we use a delay(1000) code to let the controller do nothing for 1000 ms.

delay(1000);