# Matter nRF Connect LIT ICD Example Application

The nRF Connect LIT ICD Example allows to test the device that utilizes Long
Idle Time feature from the Intermittently Connected Device Management cluster.
It uses buttons to change the 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.

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.

<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 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 device states, and LEDs to show the
state of these changes.

### 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 **Button 4**.

### 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 provisioning

The provisioning operation, which is the Last part of the rendezvous procedure,
involves sending the Thread network credentials from the Matter controller to
the Matter device. As a result, the device joins the Thread 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
Matter OTA mechanism, which is enabled by default.

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.

#### 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>    |

<hr>

## 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 network.

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

**LED 2** is used for the Identify feature purpose. 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** Pressing the button 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 3** Represents the User Active Mode Trigger feature from the
Intermittently Connected Devices Management cluster. Pressing it puts the ICD
device in the active mode and makes it responsive.

**Button 4** 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.

**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:

        $ python3 scripts/checkout_submodules.py --shallow --platform nrfconnect

> **Note**:
>
> For Linux operating system install
> [SEGGER J-Link Software](https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack).

### Install Command Line Tools

With admin permissions enabled, download and install the
[nRF Command Line Tools](https://www.nordicsemi.com/Products/Development-tools/nrf-command-line-tools).

### Install Toolchain Manager

Toolchain Manager is available from
[nRF Connect for Desktop](https://www.nordicsemi.com/Products/Development-tools/nrf-connect-for-desktop),
a cross-platform tool that provides different applications that simplify
installing the nRF Connect SDK. Both the tool and the application are available
for Windows, Linux, and macOS.

To install the Toolchain Manager app, complete the following steps:

1.  [Download nRF Connect for Desktop](https://www.nordicsemi.com/Products/Development-tools/nrf-connect-for-desktop/download#infotabs)
    for your operating system.

2.  Install and run the tool on your machine.

3.  In the **APPS** section, click **Install** button on the Toolchain Manager
    tab.

### Install nRF Connect SDK

Complete the following steps to install the nRF Connect SDK:

1.  Open Toolchain Manager in nRF Connect for Desktop.

2.  Click the **Install** button next to the
    [recommended](../../../config/nrfconnect/.nrfconnect-recommended-revision)
    version of the nRF Connect SDK.

3.  A pop-up window will inform you about the current installation directory. If
    you want to change the directory, click the **Change directory** button.
    Otherwise, click the **Continue installation** button.

4.  When the nRF Connect SDK is installed on your machine, the **Install**
    button changes to the **Open VS Code** button.

5.  Click the dropdown menu next to the **Open VS Code** button for the
    installed nRF Connect SDK version, and select **Open terminal**.

6.  Make sure that the nRF Connect SDK version is compatible with the Matter SDK
    version:

    ```
         $ cd {connectedhomeip directory}
         $ python3 scripts/setup/nrfconnect/update_ncs.py --update
    ```

Now you can proceed with the [Building](#building) instruction.

<hr>

## Building

Complete the following steps to build the sample:

1.  Navigate to the example's directory:

        $ cd examples/lit-icd-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 completely disable support for DFU, 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.

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 network.

### Testing Device Firmware Upgrade

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