# Matter nRF Connect Lock Example Application

The nRF Connect Lock Example demonstrates how to remotely control a door lock
device with one basic bolt. It uses buttons to test changing the lock and device
states and LEDs to show the state of these changes. You can use this example as
a reference for creating your own application.

<img src="../../platform/nrfconnect/doc/images/Logo_RGB_H-small.png" alt="Nordic Semiconductor logo"/>
<img src="../../platform/nrfconnect/doc/images/nRF52840-DK-small.png" alt="nRF52840 DK">

The example is based on
[Matter](https://github.com/project-chip/connectedhomeip) 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 lock device.

<hr>

## Overview

This example is running on the nRF Connect platform, which is based on Nordic
Semiconductor's
[nRF Connect SDK](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/index.html)
and [Zephyr RTOS](https://zephyrproject.org/). Visit Matter's
[nRF Connect platform overview](../../../docs/guides/nrfconnect_platform_overview.md)
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](#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.

The sample uses buttons for changing the lock and device states, and LEDs to
show the state of these changes. You can test it in the following ways:

-   Standalone, using a single DK that runs the door lock 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.

### 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 update that is mandatory for Matter-compliant devices and enabled
    by default
-   [Simple Management Protocol](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/device_mgmt/index.html#device-mgmt)
    over Bluetooth LE, an optional proprietary method that can be enabled to
    work alongside the default Matter OTA update. Note that this protocol is not
    a part of the Matter specification.

For both methods, the
[MCUboot](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/mcuboot/index.html)
bootloader solution is used to replace the old firmware image with the new one.

#### Matter Over-the-Air Update

The Matter over-the-air update 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](#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](#building-with-device-firmware-upgrade-support)
section to learn how to change MCUboot and flash configuration in this example.

<hr>

## Requirements

The application requires a specific revision of the nRF Connect SDK to work
correctly. See [Setting up the environment](#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](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-DK) | `nrf52840dk_nrf52840`      | <details><summary>nRF52840 DK</summary><img src="../../platform/nrfconnect/doc/images/nRF52840_DK_info-medium.jpg" alt="nRF52840 DK"/></details> |
| [nRF5340 DK](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF5340-DK)   | `nrf5340dk_nrf5340_cpuapp` | <details><summary>nRF5340 DK</summary><img src="../../platform/nrfconnect/doc/images/nRF5340_DK_info-medium.jpg" alt="nRF5340 DK"/></details>    |
| [nRF7002 DK](https://www.nordicsemi.com/Products/Development-hardware/nRF7002-DK)         | `nrf7002dk_nrf5340_cpuapp` | <details><summary>nRF7002 DK</summary><img src="../../platform/nrfconnect/doc/images/nRF7002-DK_Front-small.png" alt="nRF7002 DK"/></details>    |

<hr>

### 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`.

## 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.

**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)_ &mdash; 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)_ &mdash; The device is in the
    unprovisioned state and a commissioning application is connected through
    Bluetooth LE.

-   _Short Flash Off (950ms on/50ms off)_ &mdash; The device is fully
    provisioned, but does not yet have full connectivity for Thread or Wi-Fi
    network.

-   _Solid On_ &mdash; The device is fully provisioned.

**LED 2** simulates the lock bolt and shows the state of the lock. The following
states are possible:

-   _Solid On_ &mdash; The bolt is extended and the door is locked.

-   _Off_ &mdash; The bolt is retracted and the door is unlocked.

-   _Rapid Even Flashing (100 ms on/100 ms off during 2 s)_ &mdash; The
    simulated bolt is in motion from one position to another.

    Additionally, the LED starts blinking evenly (500 ms on/500 ms off) when the
    Identify command of the Identify cluster is received on the endpoint 1. The
    command’s argument can be used to specify the duration of the effect.

**Button 1** can be used for the following purposes:

-   _Pressed for less than 3 s_ &mdash; 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](#building-with-device-firmware-upgrade-support)
    instructions.

-   _Pressed for more than 3 s_ &mdash; initiates the factory reset of the
    device. Releasing the button within the 3-second window cancels the factory
    reset procedure.

**Button 2** &mdash; Pressing the button once changes the lock state to the
opposite one.

-   On nRF52840 DK, nRF5340 DK, and nRF21540 DK: Changes the lock state to the
    opposite one.

-   On nRF7002 DK:

    -   If pressed for less than three seconds, it changes the lock state to the
        opposite one.

    -   If pressed for more than three seconds, 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.

**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](../../../docs/guides/nrfconnect_examples_cli.md).

**NFC port with antenna attached** can be used to start the
[rendezvous](#bluetooth-le-rendezvous) by providing the commissioning
information from the Matter device in a data payload that can be shared using
NFC.

<hr>

## 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](https://docs.docker.com/docker-for-mac/faqs/#can-i-pass-through-a-usb-device-to-a-container).
Use the [native shell](#using-native-shell-for-setup) for building instead.

### Using Docker container for setup

To use the Docker container for setup, complete the following steps:

1.  If you do not have the nRF Connect SDK installed yet, create a directory for
    it by running the following command:

        $ mkdir ~/nrfconnect

2.  Download the latest version of the nRF Connect SDK Docker image by running
    the following command:

        $ docker pull nordicsemi/nrfconnect-chip

3.  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.

4.  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](#building) instruction.

### Using native shell for setup

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

1.  Download and install the following additional software:

    -   [nRF Command Line Tools](https://www.nordicsemi.com/Software-and-Tools/Development-Tools/nRF-Command-Line-Tools)
    -   [GN meta-build system](https://gn.googlesource.com/gn/)

2.  If you do not have the nRF Connect SDK installed, follow the
    [guide](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/gs_assistant.html#)
    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.

3.  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

4.  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](#building) instruction.

<hr>

## Building

Complete the following steps, regardless of the method used for setting up the
environment:

1.  Navigate to the example's directory:

        $ cd examples/lock-app/nrfconnect

2.  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](#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](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/scripts/partition_manager/partition_manager.html#partition-manager)
to configure flash partitions used for the bootloader application image slot
purposes. You can change these settings by defining
[static partitions](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/scripts/partition_manager/partition_manager.html#ug-pm-static).
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.

<hr>

## 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](../../../docs/guides/nrfconnect_examples_configuration.md)
page.

<hr>

## 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

<hr>

## Testing the example

Check the [CLI tutorial](../../../docs/guides/nrfconnect_examples_cli.md) to
learn how to use command-line interface of the application.

### Testing using Linux CHIPTool

Read the [CHIP Tool user guide](../../../docs/guides/chip_tool_guide.md) to see
how to use [CHIP Tool for Linux or mac OS](../../chip-tool/README.md) to
commission and control the application within a Matter-enabled Thread or Wi-Fi
network.

### Testing using Android CHIPTool

Read the
[Android commissioning guide](../../../docs/guides/nrfconnect_android_commissioning.md)
to see how to use [CHIPTool](../../../examples/android/CHIPTool/README.md) for
Android smartphones to commission and control the application within a
Matter-enabled Thread or Wi-Fi network.

### Testing Device Firmware Upgrade

Read the
[DFU tutorial](../../../docs/guides/nrfconnect_examples_software_update.md) to
see how to upgrade your device firmware.