<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title>Arduino - AnalogRead </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 »</a> | <a class="urllink" href="http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl" rel="nofollow">Forum »</a> | <a class="urllink" href="http://www.arduino.cc/playground/" rel="nofollow">Playground »</a> </div> <!--/PageLeftFmt--> <div id="pagetext"> <!--PageText--> <div id='wikitext'> <p><strong>Reference</strong> <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>analogRead()</h2> <h4>Description</h4> <p>Reads the value from the specified analog pin. The Arduino board contains a 6 channel (8 channels on the Mini and Nano), 10-bit analog to digital converter. This means that it will map input voltages between 0 and 5 volts into integer values between 0 and 1023. This yields a resolution between readings of: 5 volts / 1024 units or, .0049 volts (4.9 mV) per unit. </p> <p class='vspace'></p><p>It takes about 100 us (0.0001 s) to read an analog input, so the maximum reading rate is about 10,000 times a second. </p> <p class='vspace'></p><h4>Syntax</h4> <p>analogRead(pin) </p> <p class='vspace'></p><h4>Parameters</h4> <p>pin: the number of the analog input pin to read from (0 to 5 on most boards, 0 to 7 on the Mini and Nano) </p> <p class='vspace'></p><h4>Returns</h4> <p>int (0 to 1023) </p> <p class='vspace'></p><h4>Note</h4> <p>If the analog input pin is not connected to anything, the value returned by analogRead() will fluctuate based on a number of factors (e.g. the values of the other analog inputs, how close your hand is to the board, etc.). </p> <p class='vspace'></p><h4>Example</h4> <pre> int analogPin = 3; // potentiometer wiper (middle terminal) connected to analog pin 3 // outside leads to ground and +5V int val = 0; // variable to store the value read void setup() { Serial.begin(9600); // setup serial } void loop() { val = analogRead(analogPin); // read the input pin Serial.println(val); // debug value } </pre> <p class='vspace'></p><h4>See also</h4> <ul><li><a class='wikilink' href='AnalogWrite.html'>analogWrite</a>() </li><li><a class='wikilink' href='http://arduino.cc/en/Tutorial/AnalogInputPins'>Tutorial: Analog Input Pins</a> </li><li><a class='wikilink' href='http://arduino.cc/en/Tutorial/RCtime'>RCtime</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>