<p><span style="color: #404040; font-family: 굴림;">여러개의 LED를 켜려면 아두이노의 핀을 여러개를 사용해야한다.&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">그러나 핀 1개로 여러개의 LED또는 FND, 도트매트릭스등을 다룰수 있다.&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">즉 74hc595 shift register를 활용하여 아두이노의 포트를 확장하는 것이다.&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp;&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">74hc595는 8-bit serial-in, serial or parallel-out shift register 로&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">8비트의 데이터를 받아 병렬로 출력해주는 IC로&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">아두이노핀에서 10101010을 보내면&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">데이터를 받아 Q0핀~Q7핀에서 동시에 10101010을 각각 출력한다.&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">즉 Q0 -&gt; 1&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q1 -&gt; 0&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q2 -&gt; 1&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q3 -&gt; 0&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q4 -&gt; 1&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q5 -&gt; 0&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q6 -&gt; 1&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">&nbsp; &nbsp; Q7 -&gt; 0을 출력해준다.(핀은 아래그림 참조)&nbsp;</span><br style="color: #404040; font-family: 굴림;" /><span style="color: #404040; font-family: 굴림;">Q7'핀은 8bit이상의 데이터를 보낼때 다음의 74hc595로 데이터를 넘긴다.</span></p>