nRF5 SDK for Mesh
This example shows the implementation of a device supporting the Low Power node (LPN) feature. It emulates an occupancy sensor device through button presses and a timer.
You can use this example as the starting point for adding the LPN feature to your device, as it demonstrates all the required changes to the application. Read more about the Low Power Node feature in Low Power node feature.
When configured to interact with a device with a Generic OnOff Server model, the device running this example turns on the LED on the light switch server device upon a button press, which emulates triggering the occupancy sensor. It also sends an off message to the light switch server device after five seconds to emulate inactivity.
This example also supports the Buttonless Secure DFU Service to perform Device Firmware Upgrade over BLE. The DFU over BLE is disabled by default. See nRF5 SDK Bootloader and DFU modules for more information.
Table of contents
Running this example requires three PCA10040 Development Kits:
As the Friend feature is not supported by this version of the nRF5 SDK for Mesh, use a precompiled version of the Friend node from the Zephyr RTOS to fulfill the Friend device role. The precompiled Friend node hex files are available at
<InstallFolder>/examples/experimental_lpn/bin. See Zephyr RTOS binaries for additional information on how they were built.
You can find the light switch server example files in the following folder:
You can find the source code and the project file of the example in the following folder:
These assignments refer to the LPN device only.
To send messages between the LPN device and the light switch server device, complete the following steps:
To set up the example:
examples/experimental_lpn/bin/, and program it to the third development kit using nrfjprog:
All three devices are now running Bluetooth Mesh enabled firmware.
Before a friendship can be established between the LPN device and the Friend device, they both must be provisioned to the same mesh network. As the Low Power node example only supports the PB-GATT bearer for provisioning, use nRF Mesh mobile app (for iOS or Android) to provision and configure all three devices.
The light switch server device shows up in the nRF Mesh App as "nRF5x Mesh LPN Switch".
Application key 1through its configuration menu, if it doesn't already have it. This application key will represent the light switch application. The key will be used by the Generic OnOff client on the LPN device and the Generic OnOff server to communicate.
Application key 1to a Generic OnOff Server model that the light switch server device instantiates in its first element.
The light switch server is now a part of the mesh network, and is ready to receive messages from the LPN device.
The LPN device shows up in the nRF Mesh App as "nRF5x Mesh LPN".
Application key 1through its configuration menu, if it doesn't already have it. The key has the same role and usage as in the case of the light switch server device.
Application key 1to a Generic OnOff Client model that the LPN device instantiates in its first element.
The LPN device is now part of the mesh network and can control the LEDs of the light switch server device. It has not entered the low power mode yet, as it needs a Friend device to accept its Friend requests.
The Friend shows up in the nRF Mesh App as "Zephyr". Provision the Friend device with the nRF Mesh App. No additional configuration is needed.
After the initial configuration and provisioning are complete, the LPN device enters the idle state.
To start the friendship establishment process, press button 3 on the LPN device. The device starts searching for an appropriate Friend in the mesh network.
The LPN example always accepts the first friendship it is offered with. Establishing a friendship normally takes less than a second. If the LPN device cannot find a Friend after 5-10 seconds, all LEDs will blink intensively. You have to press button 3 again to retry.
Once the friendship is established, LED 2 turns on and stays lit throughout the friendship.
You can send on and off messages by pressing buttons 1 and 2, respectively. These buttons also control the LED 1 of the light switch server through the Generic OnOff client model.
This behavior is identical to the one in the light switch client example.
When the Low Power node is running, you can update it using DFU over BLE:
initialize()function to the following:
Pressing button 4 resets and unprovisions the LPN device.