Bluetooth: Mesh light fixture

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


The sample supports the following development kits:

Hardware platforms


Board name

Build target

nRF52840 DK




nRF52 DK




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


This sample can be used to control the state of light sources. In addition to generic on and off functions, it allows changing the light level (brightness) of a LED light.

The sample instantiates the Light Lightness Server model and the Light Lightness Control Server model. As both Light Lightness Server and the Light LC Server extend the Generic OnOff Server, the two models need to be instantiated on separate elements. For more information, see documentation on Light Lightness Control Server.

Devices are nodes with a provisionee role in a mesh network. 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 dimmable LED 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 fixture composition data for this sample:

Element 1

Element 2

Config Server

Gen. OnOff Server

Health Server

Light LC Server

Gen. Level Server

Light LC Setup Server

Gen. OnOff Server

Gen. DTT Server

Gen. Power OnOff Server

Gen. Power OnOff Setup Server

Light Lightness Server

Light Lightness Setup Server

The models are used for the following purposes:

  • The first element contains a Config Server and a Health Server. The Config Server allows configurator devices to configure the node remotely. The 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 seven other models in the first element are the product of a single instance of the Light Lightness Server. The application implements callbacks for the Light Lightness Server to control the first LED on the device using the PWM (pulse width modulation) driver.

  • The three models in the second element are the product of a single instance of the Light Lightness Control (LC) Server. The Light LC Server controls the Light Lightness Server in the first element, deciding on parameters such as fade time, lighting levels for different states, and inactivity timing. In this sample, the Light LC Server is enabled by default on startup.

Other nodes can control the Light Lightness Server through the Light LC Server, by sending On/Off messages to the Light LC Server or to the Generic OnOff Server in the second element.


It is possible to bypass the Light LC Server by directly communicating with the Light Lightness Server on the first element.

For more details, see Light Lightness Server and Light Lightness Control Server.

The model handling is implemented in src/model_handler.c, which uses the DK Button and LEDs library and the PWM API to control the LEDs on the development kit.

User interface


Can be used to input the out-of-band (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. First LED outputs the current light level of the Light Lightness Server in the first element.


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

Source file setup

This sample is split into the following source files:

  • A main.c file to handle initialization.

  • A file for handling mesh models, model_handler.c.

  • A file for handling PWM driven control of the dimmable LED, lc_pwm_led.c.

Building and running

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

See Building and programming a sample application for information about how to build and program the application.


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 Fixture 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 Fixture 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.

  • Open the Generic OnOff Server in the second element, then tap ON at the bottom of the Generic On Off Controls.

You should now see the following actions:

  1. The LED fades from 0% to 100% over 500ms Standby -> On.

  2. The LED stays at 100% for three seconds On.

  3. The LED fades from 100% to CONFIG_BT_MESH_LIGHT_CTRL_SRV_LVL_PROLONG over five seconds On -> Prolong.

  4. The LED stays at CONFIG_BT_MESH_LIGHT_CTRL_SRV_LVL_PROLONG for three seconds Prolong.

  5. The LED fades from CONFIG_BT_MESH_LIGHT_CTRL_SRV_LVL_PROLONG to 0% over five seconds Prolong -> Standby.

The default value of CONFIG_BT_MESH_LIGHT_CTRL_SRV_LVL_PROLONG is 10000 (~15%).

Light level transitions over time

Light level transitions over time


The configuration of light levels, fade time, and timeouts can be changed by altering the configuration parameters in the prj.conf file, and rebuilding the sample.


This sample uses the following nRF Connect SDK libraries:

In addition, it uses the following Zephyr libraries: