Description

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 and 0V (ground) for LOW.

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

If you do not set the pin as an OUTPUT, and connect an LED to it, when calling digitalWrite(pin, 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

Use the following function to write a digital value to a pin:

digitalWrite(pin, value)

Parameters

The function admits the following parameters:

pin: the Arduino pin number to be controlled.
value: HIGH or LOW

Returns

The function returns nothing.

Example Code

Set the Arduino digital pin 13 (built-in LED) as an OUTPUT and toggles it by alternating between HIGH and LOW at one second pace.

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