This document describes how to use mesh networking to communicate with a ARM mbed Device Connector that is a new web service hosted by ARM. However, at the time of publishing this example, the service may not yet be live or fully ready for use. If the example does not work for you, or you are having problems with it, that probably means we have not yet managed to get the service online. Please, look out for mbed Device Connector release announcements in ARM mbed. If, however, you are a mbed partner and have your own mbed Device Server setup, you can use this example application just by changing the mbed Device Server address from https://api.connector.mbed.com to your own mbed Device Server address.

This example application demonstrates how to:

• Connect a client to a 6LoWPAN ND or Thread type of mesh network.
• Register, read resource values and send observations to ARM mbed Device Connector.
• Deregister from ARM mbed Device Connector.
• Disconnect the client from the mesh network.

By default, the example application makes a 6LoWPAN ND type of bootstrap. To change the bootstrap mode to Thread you need to define (uncomment) the macro APPL_BOOTSTRAP_MODE_THREAD in the file source/main.cpp.

• An FRDM-K64F development board (client end-point).
• An mbed 6LoWPAN shield (with a radio module).
• An mbed 6LoWPAN Gateway router.
• A micro-USB cable.
• A micro-USB charger for powering the mbed 6LoWPAN Gateway router.
• An Ethernet cable.

• yotta - to build the example programs.
• ARM mbed Device Connector website - Web service running on Internet.

• Wireshark - for packet inspection and network debugging.
• PuTTY - for serial terminal emulation.

• Setup block diagram

• Connect the Gateway router with an Ethernet cable to a router/L3 switch.

• To power up the Gateway router, use a micro-USB charger connected to a wall socket or a micro-USB cable connected to a computer.

• To flash the Gateway router with the firmware, you need a micro-USB cable (see gateway flashing instructions below).

• The wireless link between the FRDM-K64F board (client end-point) and the Gateway router follows the IEEE 802.15.4 standard.

• To power up the FRDM-K64F board (client end-point), use either a micro-USB charger or a micro-USB cable. If you are using micro-USB, you can view the debug and trace messages using third party software like PuTTY.

Note!

• If you are using a virtual machine, please set your network adapter mode to Bridged.

##Setting up the environment

To set up the environment, you need to configure the mbed 6LoWPAN Gateway router and the client as follows:

1. Use an Ethernet cable to connect the mbed 6LoWPAN Gateway router to the Internet.

2. Use a micro-USB cable to connect the mbed 6LoWPAN Gateway router to your computer. The computer will list the router as removable storage.

3. The firmware for the Gateway is located in the GW_Binary folder in the root of this example. You should select the binary matching your application bootstrap mode:

   • For 6LoWPAN ND bootstrap, use gateway6LoWPANDynamic.bin.
   • For Thread bootstrap, use gatewayThreadDynamic.bin.

4. Copy the gateway binary file to the mbed 6LoWPAN Gateway router to flash the device. The device will reboot automatically after flashing. If that does not happen, push the Reset button on the board.

For client side configuration, please follow the steps below.

1. Set the application certificate as described in Setting Certificate for the application section.
2. Configure the mbed-client-example-6lowpan application to use the IPv6 address of the ARM mbed Device Connector:
   • The /source/mbedclient.cpp file contains the IPv6 address of the ARM mbed Device Connector. By default, this is set to 2607:f0d0:3701:9f::20. It can be found on line 35, as the value of MBED_DEVICE_CONNECTOR_URI. The full address format is coap://<IPv6 address>:PORT, that is coap://2607:f0d0:3701:9f::20:5684.
3. Configure the mbed-client-example-6lowpan application to use an appropriate radio channel based on your hardware. See Changing radio channel section for instructions.
4. Build mbed-client-example-6lowpan (see Build instructions).
5. Load the mbed-client-example-6lowpan application binary to the FRDM-K64F board (see Running the example application).

Note: You may need to open UDP port 5684 in your computer's firewall for the ARM mbed Device Connector to communicate with this example application.

This example uses IPv6 to communicate with the mbed Device Connector Server. The example program should automatically get an IPv6 address from the mbed 6LoWPAN Gateway router when it is connected via Ethernet.

1. Go to mbed Device Connector website and log in with your mbed.org account.
2. Navigate to Security credentials under My devices.
3. Click GET MY DEVICE SECURITY CREDENTIALS. You will get the needed certificate information as well as the endpoint name and domain.
4. Copy the created security credentials to file source/security.h.

To change the radio channel you are using:

• Clone the mbed-mesh-api repository to your work area:

git clone git@github.com:ARMmbed/mbed-mesh-api.git

• Modify the source code:

  • In your copy of the mbed-mesh-api repository, find the file ./source/include/static_config.h.

  • You need to use channel 1 for a sub-GHz module and channel 12 for a 2.4 GHz module.

    Tip: To identify which radio module you have, see the section Radio Module Identification.

    • For 6LoWPAN-ND, change the macro SCAN_CHANNEL_LIST to either 1 (1<<1) or 12 (1<<12).

    • For Thread, change the macro THREAD_RF_CHANNEL to either 1 or 12.

• Create a yotta link to your code:

   cd mbed-mesh-api
   yt link
  

• Go back to the mbed-client-example-6lowpan application folder and make a link to the cloned mbed-mesh-api repository:

   cd mbed-client-example-6lowpan
   yt link mbed-mesh-api
  

• Use the command yt ls to check that the link was established successfully and the module mbed-mesh-api points to the cloned repository.

• Make sure that you are using the same radio modules on both server and client sides:

  • If the radio module on the Gateway router supports the 2.4 GHz frequency band, the client side must have an mbed 6LoWPAN shield that uses a 2.4 GHz radio module (such as Atmel AT86RF233).

  • If the radio module on the Gateway router supports the sub-GHz frequency band, the client side must have an mbed 6LoWPAN shield that uses a sub-GHz radio module (such as Atmel AT86RF212B).

• An easy way to identify which frequency band your setup uses is to check the Antenna size on the radio module:

  • The sub-GHz band antenna is larger than the 2.4 GHz antenna.

  • For the client side (mbed 6LoWPAN shield connected to an FRDM-K64F board), see the image below:

  • For the Gateway router, see the image below:

1. Install yotta. See instructions here. On Linux, enter pip install --pre pyusb and then pip install yotta.

2. Install the necessary toolchains. See Required software.

3. Set the IPv6 address for the ARM mbed Device Connector in source/lwm2mclient.cpp if you have not done it yet. The instructions are in the Client side configuration section of this document.

4. In the command line, move to the root of this example application.

5. Set up the target device: yotta target frdm-k64f-gcc.

6. Build the binary: yotta build.

The executable file will be created in the /build/frdm-k64f-gcc/source/ folder.

1. Find the binary file mbed-client-example-6lowpan.bin in the folder mbed-client-example-6lowpan/build/frdm-k64f-gcc/source/.

2. Copy the binary to the USB mass storage root of the FRDM-K64F development board. It will be automatically flashed to the target MCU. After flashing, the board will restart itself. Press the Reset button of the development board if it does not restart automatically.

3. The program starts up and will begin registration with the ARM mbed Device Connector.

4. After a successful registration, the program will automatically start sending observations every 10 seconds.

Step 1: Go to the mbed Device Connector website.

Step 2: Log in using your mbed account.

Step 3: Click the Connected devices link under My devices to see your registered devices.

Step 4: To send requests to mbed Client device with mbed Device Connector API, click API Console under mbed Device Connector. Click the URL textbox to create a request. The textbox will show a list of registered resources. After selecting the resource press the TEST API button to send the request.

The /Test/0/S represents the static resource that is a fixed value set in the example application. For example: https://api.connector.mbed.com/endpoints/<ENDPOINT_NAME>/Test/0/S?sync=true, where <ENDPOINT_NAME> is the name of the connected device. It creates a request to the /Test/0/S resource.

The /Test/0/D represents the dynamic resource that can be read by the mbed Device Connector. It is linked with the SW2 button on the FRDM board. The value starts from zero and every time you press the SW2 button the node increases the counter value by 1. You can make a CoAP request to the node resources to get the latest value. To do that, click API Console under mbed Device Connector. Click the URL textbox to create a request.

For example: https://api.connector.mbed.com/endpoints/<ENDPOINT_NAME>/Test/0/D?sync=true, where <ENDPOINT_NAME> is the name of the connected device, creates a GET request to the /Test/0/D resource. This returns the latest value of /Test/0/D.

NOTE: If you get, for example, an error Server Response:410(Gone) or other such error, clear the cache of your browser, log out and log in again.

For more information on the mbed Device Connector REST API, see the help pages.

Step 5: If you press the SW3 button the endpoint sends a deregister message to the mbed Device Connector. After a successful deregistration, LED D12 starts blinking indicating that the application has successfully completed the task.

To see the debug trace for the mbed Client, you can use either Wireshark or terminal emulation software.

The following is an example of using PuTTY and Linux:

1. On the computer, open PuTTY with root privileges: $ sudo putty.

2. Give the command dmesgto see which serial port your mbed Client controller is connected to.

3. Go to the Serial category in PuTTY.

4. Type your identified port in the section Serial line to connect to, for example /dev/ttyACM0.

5. In the Configure the serial line section, enter the following details:

   • Baud-rate = 115200.
   • Data bits = 8.
   • Stop bits = 1.
   • flow control = xon/xoff.

6. Click the Session category. Give the session a name, for example mbed_trace, and save it.

7. Select Connection_type Serial.

8. Click Open.

This will give you the client's debug trace.

If lwm2m-client-6lowpan-endpoint is not visible in the ARM mbed Device Connector try one of the following:

• Clear your browser cache.
• Restart the 6LoWPAN Gateway.
• Restart the FRDM-K64F board.

You can also check the following settings:

• Check that channels are set as described in Changing radio channel.
• Check that the mbed 6LoWPAN Gateway is using the correct binary, as explained in Gateway configuration.
• Check that the ARM mbed Device Connector address is set to mbed-client-example-6lowpan, as explained in Client side configuration.
• Check the client trace. It should indicate that the bootstrap is ready when the FRDM-K64F board is connected to the mbed 6LoWPAN Gateway.

For example, the 6LoWPAN ND bootstrap trace window will indicate the bootstrap state and object registration as follows:

[INFO][m6LND]: 6LoWPAN ND bootstrap ready
...
[DBG ][m6LND]: Channel: 1
[DBG ][mbedclient]: mesh_network_handler() 0
[DBG ][mbedclient]: waiting 15s before sending registration...
[DBG ][mbedclient]: send_registration()
...
[DBG ][mbedclient]: object_registered()