digitalWrite

digitalWrite () Function

[Digital I/O]

Description

The digitalWrite () function is used to write a HIGH or a LOW value to a digital pin.

If the pin has been configured as an OUTPUT with pinMode (), its voltage will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) for HIGH, 0V (ground) for LOW.

If the pin is configured as an INPUT, digitalWrite () will enable (HIGH) or disable (LOW) the internal pullup on the input pin. It is recommended to set the pinMode() to INPUT_PULLUP to enable the internal pull-up resistor. 

If you do not set the pinMode () to OUTPUT, and connect an LED to a pin, when calling digitalWrite (HIGH), the LED may appear dim. Without explicitly setting pinMode (), digitalWrite () will have enabled the internal pull-up resistor, which acts like a large current-limiting resistor.

Syntax

digitalWrite (pin, value)

Parameters

pin: the Arduino pin number.

value: HIGH or LOW.

Returns

Nothing

Example Code

The code makes the digital pin 13 an OUTPUT and toggles it by alternating between HIGH and LOW at one second place.

void setup () {

  pinMode (13, OUTPUT);    // sets the digital pin 13 as output

}

void loop () {

  digitalWrite (13, HIGH); // sets the digital pin 13 on

  delay (1000);           // waits for a second

  digitalWrite (13, LOW); // sets the digital pin 13 off

  delay (1000);            // waits for a second

}

Notes and Warnings

The analog input pins can be used as digital pins, referred to as A0, A1, etc. The exception is the Arduino Nano, Pro Mini, and Mini’s A6 and A7 pins, which can only be used as analog inputs.

Also See

-digitalRead ()                                                                          

-pinMode ()