title: Arduino Nano no serial communication SIM800C
body: <p>I am trying to get my SIM800C to talk with my Arduino. There is no communication happening, though.</p>
  
  <pre class="lang-c prettyprint-override"><code>#include &lt;SoftwareSerial.h&gt;
  
  SoftwareSerial at(2, 3);
  
  void setup() {
    Serial.begin(9600);
    at.begin(9600);
  }
  
  void loop() {
    // try every 2 seconds
    delay(2000);
  
    Serial.println("sending AT ... ");
    at.println("AT");
  
    while (at.available() &gt; 0) {
      Serial.write(at.read());
    }
  }
  </code></pre>
  
  <p>I am not able to get an <code>OK</code> back. SIM800C is supposed to detect the baud rate by itself.</p>
  
  <p><a href="https://i.stack.imgur.com/FbDGT.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FbDGT.jpg" alt="wiring of Arduino and SIM800C"></a></p>
  
  <p>I am sure there has to be a simple stupid mistake. I just don't know what to do at this point. I obviously already checked for cable break. Out of desperation I already tried to switch <code>RX</code> and <code>TX</code>. I also tried different baud rates (whatever is within the usual limitations of <code>SoftwareSerial</code>) but it should automatically detect it once a couple of AT commands got in anyway.</p>