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114 lines
5.4 KiB
HTML
114 lines
5.4 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> | <a class='wikilink' href='Changes.html'>Changes</a>
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</p>
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<p class='vspace'></p><h2>digitalWrite()</h2>
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<h4>Description</h4>
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<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.
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</p>
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<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.
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</p>
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<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.
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</p>
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<p class='vspace'></p><h4>Syntax</h4>
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<p>digitalWrite(pin, value)
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</p>
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<p class='vspace'></p><h4>Parameters</h4>
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<p>pin: the pin number
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</p>
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<p class='vspace'></p><p>value: <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>Returns</h4>
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<p>none
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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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void setup()
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{
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pinMode(ledPin, OUTPUT); // sets the digital pin as output
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}
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void loop()
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{
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digitalWrite(ledPin, HIGH); // sets the LED on
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delay(1000); // waits for a second
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digitalWrite(ledPin, LOW); // sets the LED off
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delay(1000); // waits for a second
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}
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</pre>
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<p class='vspace'></p><p>Sets pin 13 to HIGH, makes a one-second-long delay, and sets the pin back to LOW.
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</p>
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<p class='vspace'></p><h4>Note</h4>
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<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).
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</p>
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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='DigitalRead.html'>digitalRead</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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