title: Connect sim800 to Raspberry PI (RX, TX)
body: <p>I've been trying to connect my sim800L to my Raspberry pi 3 model B (rasbian) but without success...</p>
  
  <p>I'm at the very first step, and since I'm new to Raspberry pi, I don't understand very well how it works.</p>
  
  <p>Here is how I'm trying to connect it:</p>
  
  <p><img src="https://i.stack.imgur.com/kyEm7.png" alt="montage"></p>
  
  <p>After some research, I've found that I needed to add some things to the <code>/boot/config.txt</code> file in order to enable the UART, so I've added this :</p>
  
  <pre><code>core_freq=250
  enable_uart
  </code></pre>
  
  <p>After, I found out a code that matched what I'm trying to do, here it is:</p>
  
  <pre><code>import serial   
  import os, time
  
  # Enable Serial Communication
  port = serial.Serial('/dev/ttyS0', baudrate=9600, timeout=1)
  
  # Transmitting AT Commands to the Modem
  # '\r\n' indicates the Enter key
  
  port.write('AT'+'\r\n')
  rcv = port.read(10)
  print rcv
  </code></pre>
  
  <p>But nothing is working in the Python Shell, when I try the AT command, which is supposed to answer OK if the sim800L is successfully connected. I'm getting some basic errors, like AT is not defined.</p>
  
  <p>How can I resolve this error?</p>