title: RN4020 PICtail™ Bluetooth Low Energy Programming
body: <p>When connecting RN4020 PICtail™ to my PC, I open the A terminal emulator application , then I type $$$ to enter the PIC18 command shell, but the only command I am able to execute is H, for all the other as SS, SF, etc.. I got an error</p>
  
  <pre><code>&gt;H
  &gt;I#X,YY-Sets/Clears IO
  &gt;I%X-Reads IO
  &gt;I@X,YY-Sets IO dir
  &gt;SS
  &gt;ERR
  &gt;SF
  &gt;ERR
  </code></pre>