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<p class='vspace'></p><h2><span class='wikiword'>SoftwareSerial</span> Library</h2>
<p>The Arduino hardware has built-in support for serial communication on pins 0 and 1 (which also goes to the computer via the USB connection). The native serial support happens via a piece of hardware (built into the chip) called a <a class='urllink' href='http://en.wikipedia.org/wiki/UART' rel='nofollow'>UART</a>. This hardware allows the Atmega chip to receive serial communication even while working on other tasks, as long as there room in the 64 byte serial buffer.
</p>
<p class='vspace'></p><p>The <span class='wikiword'>SoftwareSerial</span> library has been developed to allow serial communication on other digital pins of the Arduino, using software to replicate the functionality (hence the name "<span class='wikiword'>SoftwareSerial</span>"). It is possible to have multiple software serial ports with speeds up to 115200 bps. A parameter enables inverted signaling for devices which require that protocol.
</p>
<p class='vspace'></p><p>The version of <span class='wikiword'>SoftwareSerial</span> included in 1.0 and later is based on the <a class='urllink' href='http://arduiniana.org/libraries/newsoftserial' rel='nofollow'>NewSoftSerial library</a> by Mikal Hart.
</p>
<p class='vspace'></p><h4>Limitations</h4>
<p>The library has the following known limitations:
</p>
<p class='vspace'></p><ul><li>If using multiple software serial ports, only one can receive data at a time.
</li><li>Not all pins on the Mega and Mega 2560 support change interrupts, so only the following can be used for RX: 10, 11, 12, 13, 50, 51, 52, 53, 62, 63, 64, 65, 66, 67, 68, 69
</li><li>Not all pins on the Leonardo support change interrupts, so only the following can be used for RX: 8, 9, 10, 11, 14 (MISO), 15 (SCK), 16 (MOSI).
</li></ul><p class='vspace'></p><h4>Example</h4>
<div class='code' >
<p class='vspace'></p><p>
<div class='sourceblock ' id='sourceblock1'>
<div class='sourceblocktext'><div class="arduino"><span class="coMULTI">/*<br />
Software serial multple serial test<br />
<br />
Receives from the hardware serial, sends to software serial.<br />
Receives from software serial, sends to hardware serial.<br />
<br />
The circuit: <br />
* RX is digital pin 10 (connect to TX of other device)<br />
* TX is digital pin 11 (connect to RX of other device)<br />
<br />
Note:<br />
Not all pins on the Mega and Mega 2560 support change interrupts, <br />
so only the following can be used for RX: <br />
10, 11, 12, 13, 50, 51, 52, 53, 62, 63, 64, 65, 66, 67, 68, 69<br />
<br />
Not all pins on the Leonardo support change interrupts, <br />
so only the following can be used for RX: <br />
8, 9, 10, 11, 14 (MISO), 15 (SCK), 16 (MOSI).<br />
<br />
created back in the mists of time<br />
modified 25 May 2012<br />
by Tom Igoe<br />
based on Mikal Hart's example<br />
<br />
This example code is in the public domain.<br />
<br />
*/</span><br />
<span class="co2">#include <SoftwareSerial.h></span><br />
<br />
SoftwareSerial mySerial<span class="br0">(</span><span class="nu0">10</span><span class="sy0">,</span> <span class="nu0">11</span><span class="br0">)</span><span class="sy0">;</span> <span class="co1">// RX, TX</span><br />
<br />
<span class="kw1">void</span> <span class="kw3">setup</span><span class="br0">(</span><span class="br0">)</span> <br />
<span class="br0">{</span><br />
<span class="co1">// Open serial communications and wait for port to open:</span><br />
<span class="kw1">Serial</span>.<span class="kw1">begin</span><span class="br0">(</span><span class="nu0">57600</span><span class="br0">)</span><span class="sy0">;</span><br />
<span class="kw1">while</span> <span class="br0">(</span><span class="sy0">!</span><span class="kw1">Serial</span><span class="br0">)</span> <span class="br0">{</span><br />
<span class="sy0">;</span> <span class="co1">// wait for serial port to connect. Needed for Leonardo only</span><br />
<span class="br0">}</span><br />
<br />
<br />
<span class="kw1">Serial</span>.<span class="kw1">println</span><span class="br0">(</span><span class="st0">"Goodnight moon!"</span><span class="br0">)</span><span class="sy0">;</span><br />
<br />
<span class="co1">// set the data rate for the SoftwareSerial port</span><br />
mySerial.<span class="kw1">begin</span><span class="br0">(</span><span class="nu0">4800</span><span class="br0">)</span><span class="sy0">;</span><br />
mySerial.<span class="kw1">println</span><span class="br0">(</span><span class="st0">"Hello, world?"</span><span class="br0">)</span><span class="sy0">;</span><br />
<span class="br0">}</span><br />
<br />
<span class="kw1">void</span> <span class="kw3">loop</span><span class="br0">(</span><span class="br0">)</span> <span class="co1">// run over and over</span><br />
<span class="br0">{</span><br />
<span class="kw1">if</span> <span class="br0">(</span>mySerial.<span class="kw1">available</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><br />
<span class="kw1">Serial</span>.<span class="kw1">write</span><span class="br0">(</span>mySerial.<span class="kw1">read</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy0">;</span><br />
<span class="kw1">if</span> <span class="br0">(</span><span class="kw1">Serial</span>.<span class="kw1">available</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><br />
mySerial.<span class="kw1">write</span><span class="br0">(</span><span class="kw1">Serial</span>.<span class="kw1">read</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy0">;</span><br />
<span class="br0">}</span></div></div>
<div class='sourceblocklink'><a href='#' type='text/plain'>[Get Code]</a></div>
</div>
</p>
<p class='vspace'></p></div>
<p class='vspace'></p><h4>Functions</h4>
<ul><li><a class='wikilink' href='SoftwareSerialConstructor.html'>SoftwareSerial</a>()
</li><li><a class='wikilink' href='SoftwareSerialAvailable.html'>available</a>()
</li><li><a class='wikilink' href='SoftwareSerialBegin.html'>begin</a>()
</li><li><a class='wikilink' href='SoftwareSerialIsListening.html'>isListening</a>()
</li><li><a class='wikilink' href='SoftwareSerialOverflow.html'>overflow</a>()
</li><li><a class='wikilink' href='SoftwareSerialPeek.html'>peek</a>()
</li><li><a class='wikilink' href='SoftwareSerialRead.html'>read</a>()
</li><li><a class='wikilink' href='SoftwareSerialPrint.html'>print</a>()
</li><li><a class='wikilink' href='SoftwareSerialPrintln.html'>println</a>()
</li><li><a class='wikilink' href='SoftwareSerialListen.html'>listen</a>()
</li><li><a class='wikilink' href='SoftwareSerialWrite.html'>write</a>()
</li></ul><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://arduino.cc/forum/index.php/board,23.0.html' 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.
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