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.
Building and Running
There are configuration files for various setups in the samples/net/lwm2m_client directory:
prj.confThis is the standard default config.
overlay-bootstrap.confThis overlay config can be added to enable LWM2M Bootstrap support.
overlay-ot.confThis overlay config can be added for OpenThread support.
overlay-dtls.confThis overlay config can be added for DTLS support via MBEDTLS.
overlay-bt.confThis overlay config can be added to enable Bluetooth networking support.
overlay-queue.confThis overlay config can be added to enable LWM2M Queue Mode support.
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 native POSIX application or as a QEMU target using the default configuration
This requires a small amount of setup described in Networking with QEMU Ethernet, Networking with QEMU and Networking with native_posix 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
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:
Open up the Leshan Demo Server web UI
Click on “Security”
Click on “Add new client security configuration”
Enter the following data:
Client endpoint: qemu_x86
Security mode: Pre-Shared Key
Start the Zephyr sample
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:
Click on “Add new client bootstrap configuration”
Enter the following data:
Client endpoint: qemu_x86
LWM2M Servertab, 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
LWM2M Bootstrap Servertab 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).
To build the lwm2m-client sample for hardware requiring Bluetooth for networking (IPSP node connected via 6lowpan) do the following:
west build -b <board to use> samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-bt.conf"
The overlay-*.conf files can also be combined. For example, you could build a DTLS-enabled LwM2M client sample for BLENano2 hardware by using the following commands (requires Bluetooth for networking):
west build -b nrf52_blenano2 samples/net/lwm2m_client -- -DCONF_FILE="prj.conf overlay-bt.conf overlay-dtls.conf"
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
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