LwM2M client

Overview

Lightweight Machine to Machine (LwM2M) is an application layer protocol based on CoAP/UDP, and is designed to expose various resources for reading, writing and executing via an LwM2M server in a very lightweight environment.

This LwM2M client sample application for Zephyr implements the LwM2M library and establishes a connection to an LwM2M server using the Open Mobile Alliance Lightweight Machine to Machine Technical Specification (Section 5.3: Client Registration Interface).

The source code for this sample application can be found at: samples/net/lwm2m_client.

Requirements

• Networking with QEMU Ethernet, Networking with QEMU or Networking with native_sim board

• Linux machine

• Leshan Demo Server (https://eclipse.org/leshan/)

Building and Running

There are configuration files for various setups in the samples/net/lwm2m_client directory:

prj.conf	This is the standard default config.
overlay-bootstrap.conf	This overlay config can be added to enable LWM2M Bootstrap support.
overlay-ot.conf	This overlay config can be added for OpenThread support.
overlay-dtls.conf	This overlay config can be added for DTLS support via MBEDTLS.
overlay-queue.conf	This overlay config can be added to enable LWM2M Queue Mode support.
overlay-tickless.conf	This overlay config can be used to stop LwM2M engine for periodically interrupting socket polls. It can have significant effect on power usage on certain devices.

Build the lwm2m-client sample application like this:

west build -b <board to use> samples/net/lwm2m_client -- -DCONF_FILE=<config file to use>

The easiest way to setup this sample application is to build and run it as a native_sim application or as a QEMU target using the default configuration prj.conf. This requires a small amount of setup described in Networking with QEMU Ethernet, Networking with QEMU and Networking with native_sim board.

Download and run the latest build of the Leshan Demo Server:

$ wget https://ci.eclipse.org/leshan/job/leshan/lastSuccessfulBuild/artifact/leshan-server-demo.jar
$ java -jar ./leshan-server-demo.jar -wp 8080

You can now open a web browser to: http://localhost:8080 This is where you can watch and manage connected LwM2M devices.

Build the lwm2m-client sample application for QEMU like this:

west build -b qemu_x86 samples/net/lwm2m_client
west build -t run

The sample will start and automatically connect to the Leshan Demo Server with an IPv6 client endpoint “qemu_x86”.

To change the sample to use IPv4, disable IPv6 by changing these two configurations in prj.conf:

CONFIG_NET_IPV6=n
CONFIG_NET_CONFIG_NEED_IPV6=n

DTLS Support

To build the lwm2m-client sample for QEMU with DTLS support do the following:

west build -b qemu_x86 samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-dtls.conf"
west build -t run

Setup DTLS security in Leshan Demo Server:

1. Open up the Leshan Demo Server web UI

2. Click on “Security”

3. Click on “Add new client security configuration”

4. Enter the following data:

   • Client endpoint: qemu_x86

   • Security mode: Pre-Shared Key

   • Identity: Client_identity

   • Key: 000102030405060708090a0b0c0d0e0f

5. Start the Zephyr sample

Bootstrap Support

In order to run Bootstrap procedure with the sample, you need to download and run the Leshan Demo Bootstrap Server:

$ wget https://ci.eclipse.org/leshan/job/leshan/lastSuccessfulBuild/artifact/leshan-bsserver-demo.jar
$ java -jar ./leshan-bsserver-demo.jar -wp 8888 -lp 5783 -slp 5784

You can now open a web browser to: http://localhost:8888 The Demo Bootstrap Server web UI will open, this is where you can configure your device for bootstrap.

Configure the lwm2m-client sample in the Demo Bootstrap Server:

1. Click on “Add new client bootstrap configuration”

2. Enter the following data:

   • Client endpoint: qemu_x86

3. In the LWM2M Server tab, enter the following data:

   • LWM2M Server URL: coap://[2001:db8::2]:5683 (or coap://192.0.2.2:5683 if IPv4 is used)

   • Security mode: No Security

4. The LWM2M Bootstrap Server tab can be left intact in the default configuration (No Security).

To build the lwm2m-client sample for QEMU with Bootstrap enabled do the following:

west build -b qemu_x86 samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-bootstrap.conf"
west build -t run

The sample will start and automatically connect to the Leshan Demo Bootstrap Server to obtain the LwM2M Server information. After that, the sample will automatically connect to the Leshan Demo Sever, as it was indicated in the Bootstrap Server configuration.

It is possible to combine overlay files, to enable DTLS and Bootstrap for instance. In that case, the user should make sure to update the port number in the overlay file for Bootstrap over DTLS (5784 in case of Leshan Demo Bootstrap Server) and to configure correct security mode in the LWM2M Bootstrap Server tab in the web UI (Pre-shared Key).

OpenThread Support

To build the lwm2m-client sample for hardware requiring OpenThread for networking do the following:

west build -b <board to use> samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-ot.conf"

Note: If not provisioned (fully erased before flash), device will form new OpenThread network and promote itself to leader (Current role: leader). To join into already existing OT network, either enable CONFIG_OPENTHREAD_JOINER=y and CONFIG_OPENTHREAD_JOINER_AUTOSTART=y and send join request from other already joined device with joiner capabilities, or provision it manually from console:

ot thread stop
ot channel <channel>
ot networkname <network name>
ot masterkey <key>
ot panid <panid>
ot extpanid <extpanid>
ot thread start

You could get all parameters for existing OT network from your OTBR with the following command:

wpanctl get Thread:ActiveDataset

Queue Mode Support

To build the lwm2m-client sample with LWM2M Queue Mode support do the following:

west build -b <board to use> samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-queue.conf"

With Queue Mode enabled, the LWM2M client will register with “UDP with Queue Mode” binding. The LWM2M engine will notify the application with LWM2M_RD_CLIENT_EVENT_QUEUE_MODE_RX_OFF event when the RX window is closed so it can e. g. turn the radio off. The next RX window will be open with consecutive LWM2M_RD_CLIENT_EVENT_REG_UPDATE_COMPLETE event.

WNC-M14A2A LTE-M Modem Support

To build the lwm2m-client sample for use with the WNC-M14A2A LTE-M modem shield do the following:

west build -b <board to use> samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-wncm14a2a.conf"

Sample output without DTLS enabled

The following is sample output from the QEMU console. First, LwM2M engine is initialized. Then, several LwM2M Smart Objects register themselves with the engine. The sample app then sets some client values so that they can be seen in the Leshan Demo Server interface, and finally, the registration request is sent to the server where the endpoint is initialized.

To exit from QEMU enter: 'CTRL+a, x'
[QEMU] CPU: qemu32,+nx,+pae
qemu-system-i386: warning: Unknown firmware file in legacy mode: genroms/multiboot.bin

shell> [lib/lwm2m_engine] [DBG] lwm2m_engine_init: LWM2M engine thread started
[lwm2m_obj_security] [DBG] security_create: Create LWM2M security instance: 0
[lwm2m_obj_server] [DBG] server_create: Create LWM2M server instance: 0
[lwm2m_obj_device] [DBG] device_create: Create LWM2M device instance: 0
[lwm2m_obj_firmware] [DBG] firmware_create: Create LWM2M firmware instance: 0
[lwm2m-client] [INF] main: Run LWM2M client
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/0, value:0x0001c99e, len:6
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/1, value:0x0001c9ab, len:23
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/2, value:0x0001c9c9, len:9
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/3, value:0x0001c9d9, len:3
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/9, value:0x0041a3a4, len:1
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/10, value:0x0041a3b4, len:4
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/17, value:0x0001c9fc, len:16
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/18, value:0x0001ca14, len:5
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/20, value:0x0041a3a4, len:1
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3/0/21, value:0x0041a3b4, len:4
[lib/lwm2m_engine] [DBG] lwm2m_engine_create_obj_inst: path:3303/0
[ipso_temp_sensor] [DBG] temp_sensor_create: Create IPSO Temperature Sensor instance: 0
[lib/lwm2m_engine] [DBG] lwm2m_engine_set: path:3303/0/5700, value:0x0041a3b8, len:8
[lib/lwm2m_rd_client] [INF] lwm2m_rd_client_start: LWM2M Client: qemu_x86
[lib/lwm2m_rd_client] [INF] sm_do_init: RD Client started with endpoint 'qemu_x86' and client lifetime 0
[lib/lwm2m_rd_client] [DBG] sm_send_registration: registration sent [2001:db8::2]
[lib/lwm2m_engine] [DBG] lwm2m_udp_receive: checking for reply from [2001:db8::2]
[lib/lwm2m_rd_client] [DBG] do_registration_reply_cb: Registration callback (code:2.1)
[lwm2m-client] [DBG] rd_client_event: Registration complete
[lib/lwm2m_rd_client] [INF] do_registration_reply_cb: Registration Done (EP='EZd501ZF26')
[lib/lwm2m_engine] [DBG] lwm2m_udp_receive: reply 0x004001ec handled and removed

See also

LwM2M high-level API