Matter nRF Connect Light Switch Example Application#

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 was created to facilitate testing and certification of a Matter device communicating over a low-power, 802.15.4 Thread network, or Wi-Fi 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. In the case of Thread, this device works as a Thread Sleepy End Device. Support for both Thread and Wi-Fi is mutually exclusive and depends on the hardware platform, so only one protocol can be supported for a specific light switch device.

Overview#

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.

By default, the Matter accessory device has IPv6 networking disabled. You must pair it with the Matter controller over Bluetooth® LE to get the configuration from the controller to use the device within a Thread or Wi-Fi network. You have to make the device discoverable manually (for security reasons). See Bluetooth LE advertising to learn how to do this. The controller must get the commissioning information from the Matter accessory device and provision the device into the network.

You can test this application remotely over the Thread or the Wi-Fi protocol, which in either case requires more devices, including a Matter controller that you can configure either on a PC or a mobile device.

The sample uses buttons for controlling the bound device’s LEDs. You can test it in the following ways:

Standalone, using a single DK that runs the light switch application.
Remotely over the Thread or the Wi-Fi protocol, which in either case requires more devices, including a Matter controller that you can configure either on a PC or a mobile device.

In Matter, the following types of light switch devices are available:

Group 1: On/Off Light Switch, Dimmer Switch, Color Dimmer Switch, Control Bridge
Group 2: Generic Switch

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.

Group 1 light switch devices overview#

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.

Generic Switch#

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.

Common example settings#

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 the 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.

Bluetooth LE advertising#

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:

On nRF52840 DK, nRF5340 DK, and nRF21540 DK: Button 4.
On nRF7002 DK: Button 2.

Bluetooth LE rendezvous#

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. The emulation of the NFC tag emulation starts automatically when Bluetooth LE advertising is started and stays enabled until Bluetooth LE advertising timeout expires.

Thread or Wi-Fi provisioning#

The provisioning operation, which is the Last part of the rendezvous procedure, involves sending the Thread or Wi-Fi network credentials from the Matter controller to the Matter device. As a result, the device joins the Thread or Wi-Fi network and can communicate with other devices in the network.

Device Firmware Upgrade#

The example supports over-the-air (OTA) device firmware upgrade (DFU) using one of the two available methods:

Matter OTA DFU that is mandatory for Matter-compliant devices. This option is enabled by default.
Simple Management Protocol over Bluetooth LE from Nordic Semiconductor’s nRF Connect SDK. This is an optional proprietary method that is not part of the Matter specification and can be enabled to work alongside the default Matter OTA DFU.

For both methods, the MCUboot bootloader solution is used to replace the old firmware image with the new one.

Matter Over-the-Air DFU#

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#

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.

Bootloader#

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.

Requirements#

The application requires a specific revision of the nRF Connect SDK to work correctly. See Setting up the environment for more information.

Supported devices#

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
nRF7002 DK	`nrf7002dk_nrf5340_cpuapp`	nRF7002DK

Hardware platform

Build target

Platform image

nRF52840 DK

nrf52840dk_nrf52840

nRF52840 DK

nRF5340 DK

nrf5340dk_nrf5340_cpuapp

nRF5340 DK

nRF7002 DK

nrf7002dk_nrf5340_cpuapp

nRF7002DK

IPv6 network support#

The development kits for this sample offer the following IPv6 network support for Matter:

Matter over Thread is supported for nrf52840dk_nrf52840 and nrf5340dk_nrf5340_cpuapp.
Matter over Wi-Fi is supported for nrf7002dk_nrf5340_cpuapp.

Additional requirements for testing#

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:

Lighting Example Application

Read the CHIP Tool user guide to learn how to commission the lighting device to the same Matter network using the CHIP Tool.

Device UI#

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.

LEDs#

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 connectivity for Thread or Wi-Fi network.
Solid On — The device is fully provisioned.

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.

All LEDs

Blink in unison when the factory reset procedure is initiated.

Buttons#

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 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 instructions.
Pressed for more than 3 s — initiates the factory reset of the device. Releasing the button within the 3-second window cancels the factory reset procedure.

Button 2 can be used for the following purposes:

On nRF52840 DK, nRF5340 DK and nRF21540 DK:
- If pressed for less than 0.5 seconds, it changes the light state to the opposite one on the bound lighting device (lighting-app)
- If pressed for more than 0.5 seconds, it changes the brightness of the light on the bound lighting bulb device (lighting-app). The brightness is changing from 0% to 100% with 1% increments every 300 milliseconds as long as Button 2 is pressed.

On nRF7002 DK:

If the device is not commissioned to a Matter network, it starts the NFC tag emulation, enables Bluetooth LE advertising for the predefined period of time (15 minutes by default), and makes the device discoverable over Bluetooth LE. This button is used during the commissioning procedure.

If the device is commissioned to a Matter network, it controls the light on the bound lighting device. Depending on how long you press the button:

- If pressed for less than 0.5 seconds, it changes the light state to the opposite one on the bound lighting device ([lighting-app](../../../../../../examples/lighting-app/nrfconnect/)).

- If pressed for more than 0.5 seconds, it changes the brightness of the light on the bound lighting bulb device ([lighting-app](../../../../../../examples/lighting-app/nrfconnect/)). The brightness is changing from 0% to 100% with 1% increments every 300 milliseconds as long as **Button 2** is pressed.

Button 4

On nRF52840 DK, nRF5340 DK and nRF21540 DK:

Starts the NFC tag emulation, enables Bluetooth LE advertising for the predefined period of time (15 minutes by default), and makes the device discoverable over Bluetooth LE. This button is used during the commissioning procedure.
On nRF7002 DK:

Not available.

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.

Matter CLI commands#

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.

Setting up the environment#

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.

Using Docker container for setup#

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=$(id -u) -v ~/nrfconnect:/var/ncs -v ~/connectedhomeip:/var/chip \
     -v /dev/bus/usb:/dev/bus/usb --device-cgroup-rule "c 189:* rmw" nordicsemi/nrfconnect-chip
```
In this command:
- ~/nrfconnect can be replaced with an absolute path to the nRF Connect SDK source directory.
- ~/connectedhomeip must be replaced with an absolute path to the CHIP source directory.
- -v /dev/bus/usb:/dev/bus/usb –device-cgroup-rule “c 189: rmw”* parameters can be omitted if you are not planning to flash the example onto hardware. These parameters give the container access to USB devices connected to your computer such as the nRF52840 DK.
- –rm can be omitted if you do not want the container to be auto-removed when you exit the container shell session.
- -e RUNAS=$(id -u) is needed to start the container session as the current user instead of root.
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.

Using native shell for setup#

To use the native shell for setup, complete the following steps:

Download and install the following additional software:
- nRF Command Line Tools
- GN meta-build system
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.

Building#

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.

Removing build artifacts#

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

Building with release configuration#

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.

Building with Device Firmware Upgrade support#

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.

Changing bootloader configuration#

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.

Changing flash memory settings#

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.

Configuring the example#

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.

Example build types#

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:

debug – Debug version of the application - can be used to enable additional features for verifying the application behavior, such as logs or command-line shell.
release – Release version of the application - can be used to enable only the necessary application functionalities to optimize its performance.
no_dfu – Debug version of the application without Device Firmware Upgrade feature support - can be used only for the nRF52840 DK and nRF5340 DK, as those platforms have DFU enabled by default.

For more information, see the Configuring nRF Connect SDK examples page.

Flashing and debugging#

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

Testing the example#

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).

Commissioning the lighting device#

To commission the Lighting Example Application to the same Matter network, read the CHIP Tool user guide.

Binding cluster and endpoints#

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.

Unicast binding to a remote endpoint using the CHIP Tool for Windows or Linux#

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.

Group multicast binding to the group of remote endpoints using the CHIP Tool for Windows or Linux#

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.