Arduino Universal Serial Adapter
Sketch
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  This sketch currently only shows the four serial modes and
  uses S1-S3 to select the current mode.
  
  A trailing * after the mode indicates the current mode
  
  Button Map:
    S1: Up
    S2: Select/Enter
    S3: Down
  
  Serial Modes:
    Phone UART
    DB9 Normal
    DB9 Null Modem
    Cisco console