Bluetooth: Mesh light

The Bluetooth® mesh light sample demonstrates how to set up a mesh server model application, and control LEDs with Bluetooth mesh using the Generic OnOff models.


This sample is self-contained, and can be tested on its own. However, it is required when testing the Bluetooth: Mesh light switch sample.

This sample also provides support for point-to-point Device Firmware Update (DFU) over the Simple Management Protocol (SMP).


The sample supports the following development kits:

Hardware platforms


Board name

Build target




thingy53_nrf5340_cpuapp_ns thingy53_nrf5340_cpuapp

nRF5340 DK



nrf5340dk_nrf5340_cpuapp_ns nrf5340dk_nrf5340_cpuapp

nRF52 DK




nRF52840 DK




nRF52833 DK




nRF21540 DK




The sample also requires a smartphone with Nordic Semiconductor’s nRF Mesh mobile app installed in one of the following versions:


If you build this application for Thingy:53, it enables additional features. See Thingy:53 application guide for details.

When built for an _ns build target, the sample is configured to compile and run as a non-secure application with Cortex-M Security Extensions enabled. Therefore, it automatically includes Trusted Firmware-M that prepares the required peripherals and secure services to be available for the application.

DFU requirements

The configuration overlay overlay-dfu.conf enables DFU support in the application, and applies for the following platforms:

  • nrf52840dk_nrf52840

  • nrf21540dk_nrf52840

While this overlay configuration is only applicable for the mentioned platforms in this sample, DFU over Bluetooth Low Energy may be used on other platforms as well.

Take the flash size into consideration when using DFU over Bluetooth LE on other platforms. For example, both nRF52832 and nRF52833 have limited flash size.


Point-to-point DFU over Bluetooth Low Energy for Thingy:53 is supported by default. See Updating firmware image for more information about updating firmware image on Thingy:53.

The DFU feature also requires a smartphone with Nordic Semiconductor’s nRF Device Manager mobile app installed in one of the following versions:


The mesh light sample is a Generic OnOff Server with a provisionee role in a mesh network. There can be one or more servers in the network, for example light bulbs.

The sample instantiates up to four instances of the Generic OnOff Server model for controlling LEDs. The number of OnOff Server instances depends on available LEDs, as defined in board DTS file.

Provisioning is performed using the nRF Mesh mobile app. This mobile application is also used to configure key bindings, and publication and subscription settings of the Bluetooth mesh model instances in the sample. After provisioning and configuring the mesh models supported by the sample in the nRF Mesh mobile app, you can control the LEDs on the development kit from the app.


The provisioning is handled by the Bluetooth mesh provisioning handler for Nordic DKs. It supports four types of out-of-band (OOB) authentication methods, and uses the Hardware Information driver to generate a deterministic UUID to uniquely represent the device.


The following table shows the mesh light composition data for this sample:

Element 1

Element 2

Element 3

Element 4

Config Server

Gen. OnOff Server

Gen. OnOff Server

Gen. OnOff Server

Health Server

Gen. OnOff Server


When used with Thingy:53, Element 4 is not available. Thingy:53 supports only one RGB LED, and treats each RGB LED channel as a separate LED.

The models are used for the following purposes:

  • Generic OnOff Server instances in elements 1 to N, where N is number of on board LEDs, each control LEDs 1 to N, respectively.

  • Config Server allows configurator devices to configure the node remotely.

  • Health Server provides attention callbacks that are used during provisioning to call your attention to the device. These callbacks trigger blinking of the LEDs.

The model handling is implemented in src/model_handler.c, which uses the DK Buttons and LEDs library to control each LED on the development kit according to the matching received messages of Generic OnOff Server.

User interface


Can be used to input the OOB authentication value during provisioning. All buttons have the same functionality during this procedure.


Show the OOB authentication value during provisioning if the “Push button” OOB method is used. Show the OnOff state of the Generic OnOff Server of the corresponding element.


See Configuring your application for information about how to permanently or temporarily change the configuration.

For nRF5340 and Thingy:53, the extended advertiser has to be set manually for the network core, because the Bluetooth® Low Energy does not know that the Bluetooth mesh is enabled when built for this core. This is already done for this sample by setting CONFIG_BT_EXT_ADV=y for the network core.

Source file setup

This sample is split into the following source files:

  • main.c used to handle initialization.

  • model_handler.c used to handle mesh models.

DFU configuration

To enable the DFU feature for the supported nRF52 Series development kits, set OVERLAY_CONFIG to overlay-dfu.conf when building the sample. For example, when building from the command line, use the following command:

west build -b <BOARD> -p -- -DOVERLAY_CONFIG="overlay-dfu.conf"

The configuration overlay overlay-dfu.conf enables the DFU feature. To review the required configuration alterations, open and inspect the overlay-dfu.conf file. For more information about using configuration overlay files, see Important Build System Variables in the Zephyr documentation.

FEM support

You can add support for the nRF21540 front-end module to this sample by using one of the following options, depending on your hardware:

  • Build the sample for one board that contains the nRF21540 FEM, such as nrf21540dk_nrf52840.

  • Manually create a devicetree overlay file that describes how FEM is connected to the nRF5 SoC in your device. See Set devicetree overlays for different ways of adding the overlay file.

  • Provide nRF21540 FEM capabilities by using a shield, for example the nRF21540 EK shield that is available in the nRF Connect SDK. In this case, build the project for a board connected to the shield you are using with an appropriate variable included in the build command, for example SHIELD=nrf21540_ek. This variable instructs the build system to append the appropriate devicetree overlay file.

    To build the sample in the nRF Connect for VS Code IDE for an nRF52840 DK with the nRF21540 EK attached, add the shield variable in the build configuration’s Extra CMake arguments and rebuild the build configuration. For example: -DSHIELD=nrf21540_ek.

    See nRF Connect for VS Code extension pack documentation for more information.

    See Programming nRF21540 EK for information about how to program when you are using a board with a network core, for example nRF5340 DK.

Each of these options adds the description of the nRF21540 FEM to the devicetree. See Working with RF front-end modules for more information about FEM in the nRF Connect SDK.

To add support for other front-end modules, add the respective devicetree file entries to the board devicetree file or the devicetree overlay file.

Building and running

This sample can be found under samples/bluetooth/mesh/light in the nRF Connect SDK folder structure.

When built as firmware image for the _ns build target, the sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M). To read more about CMSE, see Processing environments.

To build the sample with Visual Studio Code, follow the steps listed on the How to build an application page in the nRF Connect for VS Code extension documentation. See Building and programming an application for other building and programming scenarios and Testing and debugging an application for general information about testing and debugging in the nRF Connect SDK.


After programming the sample to your development kit, you can test it by using a smartphone with nRF Mesh mobile app installed. Testing consists of provisioning the device and configuring it for communication with the mesh models.

Provisioning the device

The provisioning assigns an address range to the device, and adds it to the mesh network. Complete the following steps in the nRF Mesh app:

  1. Tap Add node to start scanning for unprovisioned mesh devices.

  2. Select the Mesh Light device to connect to it.

  3. Tap Identify, and then Provision, to provision the device.

  4. When prompted, select an OOB method and follow the instructions in the app.

Once the provisioning is complete, the app returns to the Network screen.

Configuring models

See Configuring mesh models using the nRF Mesh mobile app for details on how to configure the mesh models with the nRF Mesh mobile app.

Configure the Generic OnOff Server model on each element on the Mesh Light node:

  • Bind the model to Application Key 1.

    Once the model is bound to the application key, you can control the first LED on the device.

  • In the model view, tap ON (one of the Generic On Off Controls) to light up the first LED on the development kit.

Make sure to complete the configuration on each of the elements on the node to enable controlling each of the remaining three LEDs.

Running DFU

After the sample is built with the overlay-dfu.conf and programmed to your development kit, support for FOTA update is enabled. See FOTA over Bluetooth Low Energy for instructions on how to perform FOTA update and initiate the DFU process.


This sample uses the following nRF Connect SDK libraries:

In addition, it uses the following Zephyr libraries:

The sample also uses the following secure firmware component: