109 lines
4.7 KiB
HTML
109 lines
4.7 KiB
HTML
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<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>
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</p>
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<p class='vspace'></p><h2>digitalRead()</h2>
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<h4>Description</h4>
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<p>Reads the value from a specified digital pin, either <a class='wikilink' href='Constants.html'>HIGH</a> or <a class='wikilink' href='Constants.html'>LOW</a>.
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<p class='vspace'></p><h4>Syntax</h4>
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<p>digitalRead(pin)
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<p class='vspace'></p><h4>Parameters</h4>
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<p>pin: the number of the digital pin you want to read (<em>int</em>)
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</p>
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<p class='vspace'></p><h4>Returns</h4>
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<p><a class='wikilink' href='Constants.html'>HIGH</a> or <a class='wikilink' href='Constants.html'>LOW</a>
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</p>
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<p class='vspace'></p><h4>Example</h4>
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<pre>
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int ledPin = 13; // LED connected to digital pin 13
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int inPin = 7; // pushbutton connected to digital pin 7
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int val = 0; // variable to store the read value
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void setup()
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{
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pinMode(ledPin, OUTPUT); // sets the digital pin 13 as output
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pinMode(inPin, INPUT); // sets the digital pin 7 as input
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}
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void loop()
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{
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val = digitalRead(inPin); // read the input pin
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digitalWrite(ledPin, val); // sets the LED to the button's value
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}
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</pre>
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<p class='vspace'></p><p>Sets pin 13 to the same value as the pin 7, which is an input.
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</p>
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<p class='vspace'></p><h4>Note</h4>
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<p>If the pin isn't connected to anything, digitalRead() can return either HIGH or LOW (and this can change randomly).
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</p>
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<p class='vspace'></p><p>The analog input pins can be used as digital pins w/ numbers 14 (analog input 0) to 19 (analog input 5).
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<p class='vspace'></p><h4>See also</h4>
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<ul><li><a class='wikilink' href='PinMode.html'>pinMode</a>()
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</li><li><a class='wikilink' href='DigitalWrite.html'>digitalWrite</a>()
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</li><li><a class='wikilink' href='http://arduino.cc/en/Tutorial/DigitalPins'>Tutorial: Digital Pins</a>
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</li></ul><p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a>
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<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>
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</p>
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<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
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<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.
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