title: SIM800l V2 Keeps Blinking Every Second
body: <p>I'm desperately looking for a solution for my SIM800l v2. The network LED just keeps blinking every second. It does not restart but it keeps blinking and not picking up a signal.</p>
  <p>I tried powering up using a laptop USB port but it does not solve it. I also used a charger adapter that is 5V and 2A but still does not solve the problem. I also tried changing the sim card but still does not solve the problem.</p>
  <p>Here is the Wiring diagram that I followed:</p>
  <p><a href="https://i.stack.imgur.com/MEbDZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MEbDZ.png" alt="enter image description here" /></a>
  <sup>Credits to miliohm.com</sup></p>
  <p>Code:</p>
  <pre class="lang-cpp prettyprint-override"><code>SoftwareSerial sim(10, 11);
  int _timeout;
  String _buffer;
  String number = &quot;+6281222329xxx&quot;; //-&gt; change with your number
  
  void setup() {
    //delay(7000); //delay for 7 seconds to make sure the modules get the signal
    Serial.begin(9600);
    _buffer.reserve(50);
    Serial.println(&quot;Sistem Started...&quot;);
    sim.begin(9600);
    delay(1000);
    Serial.println(&quot;Type s to send an SMS, r to receive an SMS, and c to make a call&quot;);
  }
  
  void loop() {
    if (Serial.available() &gt; 0)
      switch (Serial.read()) {
      case 's':
        SendMessage();
        break;
      case 'r':
        RecieveMessage();
        break;
      case 'c':
        callNumber();
        break;
      }
  
      if (sim.available() &gt; 0)
        Serial.write(sim.read());
  }
  
  void SendMessage() {
    //Serial.println (&quot;Sending Message&quot;);
    sim.println(&quot;AT+CMGF=1&quot;);    //Sets the GSM Module in Text Mode
    delay(200);
    //Serial.println (&quot;Set SMS Number&quot;);
    sim.println(&quot;AT+CMGS=\&quot;&quot; + number + &quot;\&quot;\r&quot;); //Mobile phone number to send message
    delay(200);
    String SMS = &quot;Hello, how are you? greetings from miliohm.com admin&quot;;
    sim.println(SMS);
    delay(100);
    sim.println((char)26);// ASCII code of CTRL+Z
    delay(200);
    _buffer = _readSerial();
  }
  
  void RecieveMessage() {
    Serial.println (&quot;SIM800L Read an SMS&quot;);
    sim.println(&quot;AT+CMGF=1&quot;);
    delay(200);
    sim.println(&quot;AT+CNMI=1,2,0,0,0&quot;); // AT Command to receive a live SMS
    delay(200);
    Serial.write (&quot;Unread Message done&quot;);
  }
  
  String _readSerial() {
    _timeout = 0;
    while (!sim.available() &amp;&amp; _timeout &lt; 12000) {
      delay(13);
      _timeout++;
    }
    if (sim.available()) {
      return sim.readString();
    }
  }
  
  void callNumber() {
    sim.print (F(&quot;ATD&quot;));
    sim.print (number);
    sim.print (F(&quot;;\r\n&quot;));
    _buffer = _readSerial();
    Serial.println(_buffer);
  }
  </code></pre>