Loopback

This tutorial demonstrates simple loopback communication.

Table of contents

• Requirements
• Configuration and testing
• Troubleshooting

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Requirements

• One board running Serial example

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Configuration and testing

After building and programming the serial example:

1. Connect to the device with the interactive console:

   $ python interactive_pyaci.py -d /dev/ttyACM0 --no-logfile
   
    To control your device use d[x], type d[x]. and hit tab to see the available methods.
    x is for the device index; devices will be indexed based on the order of com ports
    given with the option -d(the first device, d[0], can also be accessed using device).
   
   Python 3.5.2 (default, Nov 17 2016, 17:05:23)
   Type 'copyright', 'credits' or 'license' for more information
   IPython 6.1.0 -- An enhanced Interactive Python. Type '?' for help.

2. Send a test Echo command to see that the device is connected:
   1. Display information about the command:

      In [1]: cmd.Echo?
      Init signature: cmd.Echo(data)
      Docstring:
      A simple loopback test command, to verify that the serial transport layer is working as
      intended.
      
      Parameters
      ----------
       data : uint8_t[254]
       Data to echo back.
      File: nrf5_sdk_for_mesh/scripts/interactive_pyaci/aci/aci_cmd.py
      Type: type

   2. Test the command:

      In [2]: send(cmd.Echo("hello world"))
      2017-08-02 10:06:29,338 - INFO - ttyACM0: {event: DeviceEchoRsp, data: {'data': bytearray(b'hello world')}}

      The send function is a helper function for sending commands to the first connected device. It accepts a CommandPacket object as a parameter. All of these are imported from aci/aci_cmd.py by the interactive script.
3. Send an Echo command to the first device by addressing the device through the list of devices d, in this case d[0]:

   In [3]: d[0].send(cmd.Echo("hello world"))
   2017-08-02 10:10:29,338 - INFO - ttyACM0: {event: DeviceEchoRsp, data: {'data': bytearray(b'hello world')}}

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Troubleshooting

You might experience the following error:

2017-08-02 10:13:45,427 - INFO - ttyACM0: cmd Echo, timeout waiting for event

In that case, you should ensure that you're connected to the correct board and verify that the example is running. You can also try resetting or reconnecting the board, or both.

Using a serial terminal emulator, you can try to send an Echo command raw:

06 02 48 65 6c 6c 6f

You should receive:

06 82 48 65 6c 6c 6f