Getting started with embeNET demo for NUCLEO-WL55JC board

This document describes how to run the embeNET demo application on NUCLEO-WL55JC boards.

What you'll need

Initial preparation of the root node

In order for the root node to communicate with the PC, we need to route USART1 via ST-LINK Virtual COM Port. You can achieve this by wiring goldpin connectors, as shown in the diagram below:

If you want to make more permanent solution, you can short the solder bridges SB6 and SB10 on the PCB, and open SB7 and SB9.

The embeNET demo package

The embeNET demo package for Nucleo-WL55JC is distributed as a single ZIP file. Unzip it into a convenient location on disk. Inside you'll find a couple of folders:

  • embenet_br - contains the border router application to run on the PC
  • embenet_demo_cubeide - contains the firmware project for the Nucleo-WL55JC boards
  • enms_visualizer - contains a PC demo application that visualizes the network

Programming the Nucleo-WL55JC boards

Download and install the STM32CubeIDE.

Once you have it installed, open it and import the project located in embenet_demo_cubeide folder.

Deploying embeNET demo application on node

Build the demo application using the Build project option.

The application should build without errors. Connect the Nucleo board that should act as a node. From the Run menu select the embenet_node_demo configuration to program the board. If the configuration is not visible, mark it as favorite in the Organize favorites... menu

Deploying embeNET demo application on root

Deploying application on root node is even simpler, as the firmware is already pre-built and comes attached to the project. Connect the Nucleo board that should act as a root and from the Run menu select cubeide_root_demo configuration.

If you have more than one Nucleo board connected to the PC, you can select which ST-Link should be used for programming root and which for the node by going into "Run configurations" menu and editing the ST-LINK S/N in the "Debugger" section of each run configurations (embenet_node_demo or embenet_root_demo).

Starting the Network

To start the network you need to connect the root Nucleo board to the PC. It should register as a COM port. Next go to the embenet_br folder and edit the config.json file that holds the border router configuration. The file will look similar to this:

{
"serial_port": "COMxx",
"interface_name": "embeNET",
"network": {
"k1": "0xc08b766277099e7d7e9c0222f168cc9e",
"panid": "0xe3be",
"prefix": "0xaaaabbbbccccdddd"
},
"join_rules": [
{
"uid": 0,
"psk": "0x46d7dc94e8ee7496ceaf54a3ab64cbeb"
}
]
}

The file has the following entries:

  • serial_port - defines COM interface for the root node, in COMxx format.
  • interface_name - defines the name of the network interface that will be created within the OS to communicate with the networked nodes
  • panid - it is the 16-bit network identifier - it should be unique for each root
  • k1 is a 128-bit, network-wide key used to authenticate information exchange in the network. This key can be specific to the network or even whole organization.
  • prefix - 64-bit IPv6 prefix of the wireless network
  • join_rules - set of join rules that define which nodes can join the network (see below)

Please edit the file to make sure that the serial_port entry matches the COM port registered for the root board.

IPv6 address of the nodes

Each node in the network, including root has an IPv6 address consisting of two parts:

prefix:uid

where the prefix is set for the network in the config.json file and the uid is the 64-bit IEEE EUI-64 identifier, also know as the MAC address. In case of Nucleo-WL55JC boards it is printed on the ST-Link chip in the bottom-left part of the board, near the micro-USB socket.

Join rules

Each node that wishes to join the embeNET network needs to be authorized by the built-in Authentication Authority. The authentication process uses a pre-shared key (psk), that needs to be configured in the nodes during commissioning. In the provided demo application firmware the key is hardcoded in main.c file. During the authentication process both the uid and psk have to match what is defined in the join_rules in order to let the node join the network. However, when uid is set to 0, EVERY node with matching psk (pre-shared key) will be able to join the network. We call it the "zero rule". It is useful for testing and experimenting, however it should probably be disabled in the real deployment.

Running the border router application

The network is started once you run the border router application embenet_br.exe. The application will try to connect to the root node and then manage the network.

This is a console application that will also log a lot of information about what is going on in the network and what packets are received from the nodes. Analyzing this log may help dealing with problems, if they arise during the further development process.

Connecting the nodes

Once the border router application is running, all nodes within the communication range, should start to join the network. Be aware that this process may take couple of minutes depending on the network topology and the state of the nodes. For example: nodes that previously joined the network may require some time to notice that the border router was restarted before they attempt to join again.

Virtual network interface

While running, the border router application registers a virtual network interface within Windows. The interface name will be set according to the config.json file. You can check the presence of this interface by running the standard Windows command:

ipconfig

Also, each connected node is reachable by ICMPv6 'ping'.

Visualizing the network

The demo package includes an application that visualizes the network. It is called enms_visualizer and it is based on the ENMS service running in the background of the network. To use it simply run the application while the network is running. After a minute or so the ENMS messages will feed the application with the current state of the network, that will be visualized as a graph, spanning from the root node.

Exemplary topology with two nodes may look like this:

Network services

A network service in embeNET, is a separated piece of functionality built around the communication over a single UDP port (rarely - multiple UDP ports). Two examples of services built into the core embeNET stack are:

  • ENMS: embeNET Network Management service that allows to gather information about the network operation from the nodes
  • BOTA: Bulk-Over-The-Air service that allows to send large portions of data (for example - new firmware) between the nodes. Note that BOTA service is not available in this demo

The users however can easily develop their own services. An example of such a custom service is implemented in the demo nodes.

Custom service in the demo application

The custom service implemented in the demo works on UDP port number 1234. Please note that this service works on remote nodes only - it is not available in root node. The service does two things:

  • periodically sends a simple text message with counter to the border router node
  • reacts to some simple text commands that control the on-boards LEDs - these commands are: led1on, led1off, led2on, led2off, led3on and led3off

There are many ways you can interact with UDP ports to test this service. One of the easiest is to use an application called UDP - Sender/Reciever app from Microsoft Store. Once you run set the mode to Sender/Receiver. Next, in the Remote IP box input the IPv6 address of the remote node that you wish to communicate with. When using the default network prefix, this IP address will have the following form:

aaaa:bbbb:cccc:dddd:<UID>

where the <UID> will be the MAC address of the node.

In the Remote Port and Local Port boxes put port number: 1234

Once you hit Connect you should see incoming text messages. You can also send some commands to light the LEDs on and off.

Next steps

In order to get to know the internals of the demo and to modify or extend it refer to Internals of the embeNET demo for NUCLEO-WL55JC board

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