Trigger remotely 6P packets over serial port, openvisualizer and ZMQ

Goal: Send a command through a serial port to a mote to make it send a 6P packet.

Requierements: You need a 6TiSCH network up and running. See Kickstart Linux to get started.

Usually, we would get this working by using the command line of OpenVisualizer:

set /dev/ttyUSB0 6pAdd [6,7]

This would send the following bytes over the serial bus towards the mote:

[67, 9, 2, 6, 7] in decimal

Explanation:

67 indicates the char 'C', the mote can recognize this is a command, rather a packet send to mote. https://github.com/openwsn-berkeley/openwsn-sw/blob/develop/software/openvisualizer/openvisualizer/moteConnector/OpenParser.py#L22
9 is the commandId for 6pAdd https://github.com/openwsn-berkeley/openwsn-sw/blob/develop/software/openvisualizer/openvisualizer/moteState/moteState.py#L416
2 is the length of the payload of 6pAdd command (in bytes)
6 and 7 are the two bytes of data.

Now we are going to send it over a ZMQ socket. To do that we will use the following script:

#!/usr/bin/env python
import zmq

zmq_inject_port = 60000
d = {"signal": "cmdToMote",
     "data": {"action": ["imageCommand", "6pAdd", "[6,7]"],
              "serialPort": "/dev/ttyUSB0"},
     "sender": "mySender"}
context = zmq.Context()
publisher = context.socket(zmq.REQ)
publisher.connect("tcp://localhost:%d" % zmq_inject_port)
publisher.send_json(d)

You can tell whether a given 6P request passed or failed depending on its return code. Return codes are documented there:

https://github.com/openwsn-berkeley/openwsn-fw/blob/develop/openstack/02b-MAChigh/sixtop.h