# 3.1 LED Blinking

## Hardware Wiring

![LED Blinking](https://2341898987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LCFDbcteyTR3tQSs-5x%2F-LCFE4dCRQBMq1ajywfh%2F-LCFE7WNSkDx5xhe3mti%2F002_ledblinking.jpg?generation=1526059549009876\&alt=media)

## Sketch

The code can be found at [Examples\_Arduino - geek-workshop - studynotes - \_002\_LED\_Blinking - \_002\_LED\_Blinking.ino](https://github.com/LongerVisionRobot/Examples_Arduino/blob/master/geek-workshop/studynotes/_002_LED_Blinking/_002_LED_Blinking.ino).

```
/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.

  This example code is in the public domain.
 */

// Pin 9 has an LED connected on most Arduino boards.
// give it a name:
int led = 9;

// the setup routine runs once when you press reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);     
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}
```

## Verify & Compile

In Arduino IDe, to compile the above codes, click **Sketch->Verify/Compile**; to upload the code onto Arduino board afterwards, click **Sketch->Upload**.