<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
  <title>Arduino - DigitalWrite </title>
  <link rel='stylesheet' href='arduino.css' type='text/css' />
  <meta name="verify-v1" content="TtxFIEJAB6zdJ509wLxjnapQzKAMNm9u0Wj4ho6wxIY=" />
</head>
<body>
<div id="page">
<!--PageHeaderFmt-->
<div id="pageheader">
  <div class="title"><a href="http://www.arduino.cc"/>Arduino</a></div>
  <div class="search">
    <!-- SiteSearch Google -->
    <FORM method=GET action="http://www.google.com/search">
    <input type=hidden name=ie value=UTF-8>
    <input type=hidden name=oe value=UTF-8>
    <INPUT TYPE=text name=q size=25 maxlength=255 value="">
    <INPUT type=submit name=btnG VALUE="search">
    <input type=hidden name=domains value="http://www.arduino.cc/">
    <input type=hidden name=sitesearch value="http://www.arduino.cc/">
    </FORM>
    <!-- SiteSearch Google -->
  </div>
</div>
<!--/PageHeaderFmt-->
<!--PageLeftFmt-->
<div id="pagenav" style="text-align: right">
  <div style="float: left;">
  <p><a class='wikilink' href='http://arduino.cc/en/Main/Buy'>Buy</a>
|
<a class='wikilink' href='http://arduino.cc/en/Main/Software'>Download</a>
|
<a class='wikilink' href='Guide_index.html'>Getting Started</a>
|
<a class='wikilink' href='http://arduino.cc/en/Tutorial/HomePage'>Learning</a>
|
<a class='wikilink' href='index.html'>Reference</a>
|
<a class='wikilink' href='http://arduino.cc/en/Main/Hardware'>Hardware</a>
|
<a class='wikilink' href='FAQ.html'>FAQ</a>
</p>
<p class='vspace'></p>

  </div>
  <a class="urllink" href="http://www.arduino.cc/blog/" rel="nofollow">Blog &raquo;</a> |
  <a class="urllink" href="http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl" rel="nofollow">Forum &raquo;</a> |
  <a class="urllink" href="http://www.arduino.cc/playground/" rel="nofollow">Playground &raquo;</a>
</div>
<!--/PageLeftFmt-->
<div id="pagetext">
<!--PageText-->
<div id='wikitext'>
<p><strong>Reference</strong> &nbsp;  <a class='wikilink' href='index.html'>Language</a> (<a class='wikilink' href='Extended.html'>extended</a>) | <a class='wikilink' href='Libraries.html'>Libraries</a> | <a class='wikilink' href='Comparison.html'>Comparison</a> | <a class='wikilink' href='Changes.html'>Changes</a>
</p>
<p class='vspace'></p><h2>digitalWrite()</h2>
<h4>Description</h4>
<p>Write a <a class='wikilink' href='Constants.html'>HIGH</a> or a <a class='wikilink' href='Constants.html'>LOW</a> value to a digital pin.
</p>
<p class='vspace'></p><p>If the pin has been configured as an OUTPUT with <a class='wikilink' href='PinMode.html'>pinMode</a>(), its voltage will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) for HIGH, 0V (ground) for LOW.
</p>
<p class='vspace'></p><p>If the pin is configured as an INPUT, writing a HIGH value with digitalWrite()  will enable an internal 20K pullup resistor (see the <a class='wikilink' href='http://arduino.cc/en/Tutorial/DigitalPins'>tutorial on digital pins</a>).  Writing LOW will disable the pullup. The pullup resistor is enough to light an LED dimly, so if <span class='wikiword'>LEDs</span> appear to work, but very dimly, this is a likely cause. The remedy is to set the pin to an output with the pinMode() function.
</p>
<p class='vspace'></p><h4>Syntax</h4>
<p>digitalWrite(pin, value)
</p>
<p class='vspace'></p><h4>Parameters</h4>
<p>pin: the pin number
</p>
<p class='vspace'></p><p>value: <a class='wikilink' href='Constants.html'>HIGH</a> or <a class='wikilink' href='Constants.html'>LOW</a>
</p>
<p class='vspace'></p><h4>Returns</h4>
<p>none
</p>
<p class='vspace'></p><h4>Example</h4>
<pre> 
int ledPin = 13;                 // LED connected to digital pin 13

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  digitalWrite(ledPin, HIGH);   // sets the LED on
  delay(1000);                  // waits for a second
  digitalWrite(ledPin, LOW);    // sets the LED off
  delay(1000);                  // waits for a second
}

</pre>
<p class='vspace'></p><p>Sets pin 13 to HIGH, makes a one-second-long delay, and sets the pin back to LOW.
</p>
<p class='vspace'></p><h4>Note</h4>
<p>The analog input pins can also be used as digital pins, referred to as numbers 14 (analog input 0) to 19 (analog input 5).
</p>
<p class='vspace'></p><h4>See also</h4>
<ul><li><a class='wikilink' href='PinMode.html'>pinMode</a>()
</li><li><a class='wikilink' href='DigitalRead.html'>digitalRead</a>()
</li><li><a class='wikilink' href='http://arduino.cc/en/Tutorial/DigitalPins'>Tutorial: Digital Pins</a>
</li></ul><p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a>
</p>
<p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?board=swbugs' rel='nofollow'>Forum</a>.</em>
</p>
<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
<a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>.  Code samples in the reference are released into the public domain.
</p>
</div>

</div>
<!--PageFooterFmt-->
<div id="pagefooter">
  <a href='#'>Edit Page</a> | <a href='#'>Page History</a> | <a href='#' target='_blank'>Printable View</a> | <a href='http://arduino.cc/en/Site/AllRecentChanges'>All Recent Site Changes</a>
</div>
<!--/PageFooterFmt-->
</div>
</body>
</html>