The nRF Connect Light Switch Example demonstrates how to remotely control a lighting devices such as light bulbs or LEDs. The application should be used together with the lighting app example. The light switch uses buttons to test changing the lighting application example LED state and works as a brightness dimmer. You can use this example as a reference for creating your own application.
The example is based on Matter and Nordic Semiconductor's nRF Connect SDK, and supports remote access and control of a lighting examples over a low-power, 802.15.4 Thread network.
The example behaves as a Matter accessory, that is a device that can be paired into an existing Matter network and can be controlled by this network. The device works as a Thread Sleepy End Device.
This example is running on the nRF Connect platform, which is based on Nordic Semiconductor‘s nRF Connect SDK and Zephyr RTOS. Visit Matter’s nRF Connect platform overview to read more about the platform structure and dependencies.
In Matter, the following types of light switch devices are available:
The first type (here referred to as Group 1) uses client application clusters (for example, Level Control) and bindings to send commands to the server clusters. This type of switch is on the endpoint 1 of this example.
With the second type (Group 2), controllers can use event subscriptions to be informed about changes on the switch server cluster. This type of switch is on the endpoint 2 of this example.
A light switch device is a simple embedded controller, which has the ability to control lighting devices, such as light bulbs or LEDs. After commissioning into a Matter network, the light switch device does not know what it can control. In other words, it has no information about another device being connected to the same network. You must provide this information to the light switch through the process called binding, which links clusters and endpoints on both devices, so that the devices can interact with each other. This functionality is on the endpoint 1 and triggered by Button 2.
The Generic Switch on the endpoint 2 offers the switch server cluster. It implements the Momentary Switch (MS) and Momentary Switch Release (MSR) features. For this reason, it sends event notifications InitialPress and ShortRelease if Button 3 of the DK is pressed and released.
The Matter device that runs the light switch application is controlled by the Matter controller device over the Thread protocol. By default, the Matter device has Thread disabled, and it should be paired with Matter controller and get configuration from it. Some actions required before establishing full communication are described below.
The example can be configured to use the secure bootloader and utilize it for performing over-the-air Device Firmware Upgrade using Bluetooth LE.
In this example, to commission the device onto a Matter network, it must be discoverable over Bluetooth LE. For security reasons, you must start Bluetooth LE advertising manually after powering up the device by pressing Button 4.
In this example, the commissioning procedure is done over Bluetooth LE between a Matter device and the Matter controller, where the controller has the commissioner role.
To start the rendezvous, the controller must get the commissioning information from the Matter device. The data payload is encoded within a QR code, printed to the UART console, and shared using an NFC tag. NFC tag emulation starts automatically when Bluetooth LE advertising is started and stays enabled until Bluetooth LE advertising timeout expires.
Last part of the rendezvous procedure, the provisioning operation involves sending the Thread network credentials from the Matter controller to the Matter device. As a result, the device is able to join the Thread network and communicate with other Thread devices in the network.
The example supports over-the-air (OTA) device firmware upgrade (DFU) using one of the two available methods:
For both methods, the MCUboot bootloader solution is used to replace the old firmware image with the new one.
The Matter over-the-air DFU distinguishes two types of nodes: OTA Provider and OTA Requestor.
An OTA Provider is a node that hosts a new firmware image and is able to respond on an OTA Requestor's queries regarding availability of new firmware images or requests to start sending the update packages.
An OTA Requestor is a node that wants to download a new firmware image and sends requests to an OTA Provider to start the update process.
Simple Management Protocol (SMP) is a basic transfer encoding that is used for device management purposes, including application image management. SMP supports using different transports, such as Bluetooth LE, UDP, or serial USB/UART.
In this example, the Matter device runs the SMP Server to download the application update image using the Bluetooth LE transport.
See the Building with Device Firmware Upgrade support section to learn how to enable SMP and use it for the DFU purpose in this example.
MCUboot is a secure bootloader used for swapping firmware images of different versions and generating proper build output files that can be used in the device firmware upgrade process.
The bootloader solution requires an area of flash memory to swap application images during the firmware upgrade. Nordic Semiconductor devices use an external memory chip for this purpose. The memory chip communicates with the microcontroller through the QSPI bus.
See the Building with Device Firmware Upgrade support section to learn how to change MCUboot and flash configuration in this example.
The application requires a specific revision of the nRF Connect SDK to work correctly. See Setting up the environment for more information.
The example supports building and running on the following devices:
| Hardware platform | Build target | Platform image |
|---|---|---|
| nRF52840 DK | nrf52840dk_nrf52840 | nRF52840 DK |
| nRF5340 DK | nrf5340dk_nrf5340_cpuapp | nRF5340 DK |
If you want to test the Light Switch Example application with other devices, you also need to flash and program the following examples using the compatible development kits:
Read the CHIP Tool user guide to learn how to commission the lighting device to the same Matter network using the CHIP Tool.
This section lists the User Interface elements that you can use to control and monitor the state of the device. These correspond to PCB components on the platform image.
This section describes all behaviors of LEDs located on platform image.
LED 1 shows the overall state of the device and its connectivity. The following states are possible:
Short Flash On (50 ms on/950 ms off) — The device is in the unprovisioned (unpaired) state and is waiting for a commissioning application to connect.
Rapid Even Flashing (100 ms on/100 ms off) — The device is in the unprovisioned state and a commissioning application is connected through Bluetooth LE.
Short Flash Off (950ms on/50ms off) — The device is fully provisioned, but does not yet have full Thread network or service connectivity.
Solid On — The device is fully provisioned and has full Thread network and service connectivity.
LED 2 simulates the BLE DFU process. The following states are possible:
Off — BLE is not advertising and DFU can not be performed.
Rapid Even Flashing (30 ms off / 170 ms on) — BLE is advertising, DFU process can be started.
LED 3 can be used to identify the device. The LED starts blinking evenly (500 ms on/500 ms off) when the Identify command of the Identify cluster is received. The command's argument can be used to specify the duration of the effect.
This section describes a reaction to pressing or holding buttons located on the platform image.
Button 1 can be used for the following purposes:
Pressed for 6 s — Initiates the factory reset of the device. Releasing the button within the 3-second window cancels the factory reset procedure. LEDs 1-4 blink in unison when the factory reset procedure is initiated.
Pressed for less than 3 s — Initiates the OTA software update process. This feature is disabled by default, but can be enabled by following the Building with Device Firmware Upgrade support instruction.
Button 2 can be used for the following purposes:
Pressed once — Changes the light state to the opposite one on a bound lighting bulb device (lighting-app example).
Pressed for more than 2 s — Changes the brightness of the light on a bound lighting bulb device (lighting-app example) (dimmer functionality). The brightness is changing from 0% to 100% with 1% increments every 300 milliseconds as long as Button 2 is pressed.
Button 3 can be used for the following purposes:
CurrentPosition and (if subscribed) sends the event notifications to the controller.Button 4 can be used to start the NFC tag emulation and enable Bluetooth LE advertising for the predefined period of time (15 minutes by default).
SEGGER J-Link USB port can be used to get logs from the device or communicate with it using the command line interface.
NFC port with antenna attached can be used to start the rendezvous by providing the commissioning information from the Matter device in a data payload that can be shared using NFC.
The Matter CLI allows to run commands via serial interface after USB cable connection to Nordic Semiconductor's kit.
To enable the Matter CLI, you must compile the Light Switch Example application with the additional option -DCONFIG_CHIP_LIB_SHELL=y. Run the following command with build-target replaced with the build target name of Nordic Semiconductor's kit you are using (for example, nrf52840dk_nrf52840):
west build -b build-target -- -DCONFIG_CHIP_LIB_SHELL=y
You can use the following commands to control a device that is programmed with the Light Switch Example application by using the Matter CLI:
uart:~$ switch onoff on : sends unicast On command to bound device uart:~$ switch onoff off : sends unicast Off command to bound device uart:~$ switch onoff toggle : sends unicast Toggle command to bound device
You can use the following commands a group of devices that are programmed with the Light Switch Example application by using the Matter CLI:
uart:~$ switch groups onoff on : sends multicast On command to all bound devices in a group uart:~$ switch groups onoff off : sends multicast Off command to all bound devices in a group uart:~$ switch groups onoff toggle : sends multicast Toggle command to all bound devices in a group
Check the CLI user guide to learn how to use other CLI commands of the application.
Before building the example, check out the Matter repository and sync submodules using the following command:
$ git submodule update --init
The example requires a specific revision of the nRF Connect SDK. You can either install it along with the related tools directly on your system or use a Docker image that has the tools pre-installed.
If you are a macOS user, you won't be able to use the Docker container to flash the application onto a Nordic development kit due to certain limitations of Docker for macOS. Use the native shell for building instead.
To use the Docker container for setup, complete the following steps:
If you do not have the nRF Connect SDK installed yet, create a directory for it by running the following command:
$ mkdir ~/nrfconnect
Download the latest version of the nRF Connect SDK Docker image by running the following command:
$ docker pull nordicsemi/nrfconnect-chip
Start Docker with the downloaded image by running the following command, customized to your needs as described below:
$ docker run --rm -it -e RUNAS=$(id -u) -v ~/nrfconnect:/var/ncs -v ~/connectedhomeip:/var/chip \
-v /dev/bus/usb:/dev/bus/usb --device-cgroup-rule "c 189:* rmw" nordicsemi/nrfconnect-chip
In this command:
Update the nRF Connect SDK to the most recent supported revision, by running the following command:
$ cd /var/chip $ python3 scripts/setup/nrfconnect/update_ncs.py --update
Now you can proceed with the Building instruction.
To use the native shell for setup, complete the following steps:
Download and install the following additional software:
If you do not have the nRF Connect SDK installed, follow the guide in the nRF Connect SDK documentation to install the latest stable nRF Connect SDK version. Since command-line tools will be used for building the example, installing SEGGER Embedded Studio is not required.
If you have the SDK already installed, continue to the next step and update the nRF Connect SDK after initializing environment variables.
Initialize environment variables referred to by the CHIP and the nRF Connect SDK build scripts. Replace nrfconnect-dir with the path to your nRF Connect SDK installation directory, and toolchain-dir with the path to GNU Arm Embedded Toolchain.
$ source nrfconnect-dir/zephyr/zephyr-env.sh $ export ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb $ export GNUARMEMB_TOOLCHAIN_PATH=toolchain-dir
Update the nRF Connect SDK to the most recent supported revision by running the following command (replace matter-dir with the path to Matter repository directory):
$ cd matter-dir $ python3 scripts/setup/nrfconnect/update_ncs.py --update
Now you can proceed with the Building instruction.
Complete the following steps, regardless of the method used for setting up the environment:
Navigate to the example's directory:
$ cd examples/light-switch-app/nrfconnect
Run the following command to build the example, with build-target replaced with the build target name of the Nordic Semiconductor's kit you own, for example nrf52840dk_nrf52840:
$ west build -b build-target
You only need to specify the build target on the first build. See Requirements for the build target names of compatible kits.
The output zephyr.hex file will be available in the build/zephyr/ directory.
If you're planning to build the example for a different kit or make changes to the configuration, remove all build artifacts before building. To do so, use the following command:
$ rm -r build
To build the example with release configuration that disables the diagnostic features like logs and command-line interface, run the following command:
$ west build -b build-target -- -DCONF_FILE=prj_release.conf
Remember to replace build-target with the build target name of the Nordic Semiconductor's kit you own.
Support for DFU using Matter OTA is enabled by default.
To enable DFU over Bluetooth LE, run the following command with build-target replaced with the build target name of the Nordic Semiconductor kit you are using (for example nrf52840dk_nrf52840):
$ west build -b build-target -- -DCONFIG_CHIP_DFU_OVER_BT_SMP=y
To completely disable support for both DFU methods, run the following command with build-target replaced with the build target name of the Nordic Semiconductor kit you are using (for example nrf52840dk_nrf52840):
$ west build -b build-target -- -DCONF_FILE=prj_no_dfu.conf
Note:
There are two types of Device Firmware Upgrade modes: single-image DFU and multi-image DFU. Single-image mode supports upgrading only one firmware image, the application image, and should be used for single-core nRF52840 DK devices. Multi-image mode allows to upgrade more firmware images and is suitable for upgrading the application core and network core firmware in two-core nRF5340 DK devices.
To change the default MCUboot configuration, edit the prj.conf file located in the child_image/mcuboot directory.
Make sure to keep the configuration consistent with changes made to the application configuration. This is necessary for the configuration to work, as the bootloader image is a separate application from the user application and it has its own configuration file.
In the default configuration, the MCUboot uses the Partition Manager to configure flash partitions used for the bootloader application image slot purposes. You can change these settings by defining static partitions. This example uses this option to define using an external flash.
To modify the flash settings of your board (that is, your build-target, for example nrf52840dk_nrf52840), edit the pm_static_dfu.yml file located in the configuration/build-target/ directory.
The Zephyr ecosystem is based on Kconfig files and the settings can be modified using the menuconfig utility.
To open the menuconfig utility, run the following command from the example directory:
$ west build -b build-target -t menuconfig
Remember to replace build-target with the build target name of the Nordic Semiconductor's kit you own.
Changes done with menuconfig will be lost if the build directory is deleted. To make them persistent, save the configuration options in the prj.conf file.
The example uses different configuration files depending on the supported features. Configuration files are provided for different build types and they are located in the application root directory.
The prj.conf file represents a debug build type. Other build types are covered by dedicated files with the build type added as a suffix to the prj part, as per the following list. For example, the release build type file name is prj_release.conf. If a board has other configuration files, for example associated with partition layout or child image configuration, these follow the same pattern.
Before you start testing the application, you can select one of the build types supported by the sample. This sample supports the following build types, depending on the selected board:
For more information, see the Configuring nRF Connect SDK examples page.
To flash the application to the device, use the west tool and run the following command from the example directory:
$ west flash --erase
If you have multiple development kits connected, west will prompt you to pick the correct one.
To debug the application on target, run the following command from the example directory:
$ west debug
After building and flashing the example, you can test its functionalities. For this purpose, you need to prepare a second device that is programmed with the Lighting Example, perform the binding process, and add Access Control Lists (ACLs).
To commission the Lighting Example Application to the same Matter network, read the CHIP Tool user guide.
Binding links clusters and endpoints on both devices, which enables them to communicate with each other.
To perform binding, you need a controller that can write the binding table to the light switch device and write proper ACL to the endpoint light bulb on the Lighting Example application). For example, you can use the CHIP Tool for Windows or Linux as the controller. The ACL should contain information about all clusters that can be called by the light switch application. See the section about interacting with ZCL clusters in the CHIP Tool's user guide for more information about ACLs.
You can perform the binding process to a single remote endpoint (unicast binding) or to a group of remote endpoints (group multicast).
Note: To use a light switch without brightness dimmer, apply only the first binding command with cluster no. 6.
In this scenario, commands are provided for a light switch device with the nodeId = 2 and a light bulb device with nodeId = 1, both commissioned to the same Matter network.
To perform the unicast binding process, complete the following steps:
Build the CHIP Tool according to the steps from the CHIP Tool user guide.
Go to the CHIP Tool build directory.
Add an ACL to the development kit that is programmed with the Lighting Application Example by running the following command:
chip-tool accesscontrol write acl '[{"fabricIndex": 1, "privilege": 5, "authMode": 2, "subjects": [112233], "targets": null}, {"fabricIndex": 1, "privilege": 3, "authMode": 2, "subjects": [2], "targets": [{"cluster": 6, "endpoint": 1, "deviceType": null}, {"cluster": 8, "endpoint": 1, "deviceType": null}]}]' 1 0
In this command:
{"fabricIndex": 1, "privilege": 5, "authMode": 2, "subjects": [112233], "targets": null} is an ACL for the communication with the CHIP Tool.{"fabricIndex": 1, "privilege": 5, "authMode": 2, "subjects": [2], "targets": [{"cluster": 6, "endpoint": 1, "deviceType": null}, {"cluster": 8, "endpoint": 1, "deviceType": null}]} is an ACL for binding (cluster no. 6 is the On/Off cluster and the cluster no. 8 is the Level Control cluster).This command adds permissions on the lighting application device that allows it to receive commands from the light switch device.
Add a binding table to the Light Switch binding cluster:
chip-tool binding write binding '[{"fabricIndex": 1, "node": 1, "endpoint": 1, "cluster": 6}, {"fabricIndex": 1, "node": 1, "endpoint": 1, "cluster": 8}]' 2 1
In this command:
{"fabricIndex": 1, "node": <1>, "endpoint": 1, "cluster": 6} is a binding for the On/Off cluster.{"fabricIndex": 1, "node": <1>, "endpoint": 1, "cluster": 8} is a binding for the Level Control cluster.Note: When a light switch device reboots, the binding table is restored from flash memory and the device tries to bind a known device that is programmed with the Lighting Application Example.
The group multicast binding lets you control more than one lighting device at a time using a single light switch.
The group multicast binding targets all development kits that are programmed with the Lighting Application Example and added to the same multicast group. After the binding is established, the light switch device can send multicast requests, and all of the devices in the bound groups can run the received command.
In this scenario, commands are provided for a light switch device with the nodeId = 2 and a light bulb device with nodeId = 1, both commissioned to the same Matter network.
To perform the unicast binding process, complete the following steps:
Build the CHIP Tool according to the steps from the CHIP Tool user guide.
Go to the CHIP Tool build directory.
Add the light switch device to the multicast group by running the following command:
chip-tool tests TestGroupDemoConfig --nodeId 1
Add all light bulbs to the same multicast group by applying command below for each of the light bulbs, using the appropriate <node_id> (the user-defined ID of the node being commissioned except 2 due to use this <node_id> for light-switch) for each of them:
chip-tool tests TestGroupDemoConfig --nodeId <node_id>
Add Binding commands for group multicast:
chip-tool binding write binding '[{"fabricIndex": 1, "group": 257}]' 2 1
To test the communication between the light switch device and the bound devices, use light switch buttons or Matter CLI commands, as described in the Device UI section.
To test the Generic Switch, complete the following steps:
Enter the interactive mode of the CHIP Tool:
chip-tool interactive start
Subscribe to the InitialPress and ShortRelease event notifications:
switch subscribe-event initial-press 1 20 <node_id> 2 --is-urgent true switch subscribe-event short-release 1 20 <node_id> 2 --is-urgent true --keepSubscriptions true
Read the DFU tutorial to see how to upgrade your device firmware.