Writing your first Arduino Program

Blinking an LED 

Arduino has on-board LED at PIN13, which can be used for testing purpose. The program for blinking an LED for 1 second, can be written with the following methods.

void setup()

{

     pinMode(13, OUTPUT);      //Set the PIN 13 as output.

}

void loop ()

{

    digitalWrite(13, HIGH);           //Set PIN 13 High.

    delay(1000);                           //Wait for 1 sec.

    digitalWrite(13, LOW);            //Set PIN 13 Low.

    delay(1000);                           //Wait for 1 sec.

}

You can give a name to the PIN no.-

• By declaring a variable to the PIN no.  

int LED=13;

void setup()

{

    pinMode(LED, OUTPUT);      //Set the PIN 13 as output.

}

void loop ()

{

    digitalWrite(LED, HIGH);           //Set PIN 13 High.

    delay(1000);                           //Wait for 1 sec.

    digitalWrite(LED, LOW);            //Set PIN 13 Low.

    delay(1000);                           //Wait for 1 sec.

}

•  Or by defining the pin-

#define LED 13

#define TIME 1000

void setup()

{

    pinMode(LED, OUTPUT);      //Set the PIN 13 as output.

}

void loop ()

{

    digitalWrite(LED, HIGH);           //Set PIN 13 High.

    delay(TIME);                           //Wait for 1 sec.

    digitalWrite(LED, LOW);            //Set PIN 13 Low.

    delay(TIME);                           //Wait for 1 sec.

}

 :Where- #define is a directive command which tells the compiler that, whenever the terms LED, and TIME come, replace them by 13 and 1000 respectively.