  '~' followed by '1' -> Set the UART speed to 115200 baud
  '~' followed by '2' -> Set the UART speed to 250000 baud
  '~' followed by '3' -> Set the UART speed to 500000 baud
- 
+ '~' followeb by '~' -> Sends the bridge's shutdown command to
+                        obtain the console.
+                        
  The circuit:
  * Arduino Yun
  

      } else if (c == '3') {          //     '3' key pressed?
        Serial1.begin(500000);        //        set speed to 500000
        Serial.println("Speed set to 500000");
      } else {                        //     any other key pressed?
        Serial1.write('~');           //        write '~' to Linino
        Serial1.write(c);             //        write char to Linino

    char c = (char)Serial1.read();    // read from Linino  
    Serial.write(c);                  // write to USB-serial
  }
}