Bluetooth Mesh: Light Switch

Overview

This project demonstrates how to use Bluetooth Mesh to control light sources in a network. It uses the Generic OnOff Client model to send commands to other devices in the same mesh network. The light switch acts as a client, while the light sources act as servers.

You can pair this project with the Bluetooth Mesh Light to see how it works in a real mesh network.

Key Features:

• Control light sources using buttons on a development kit.
• Support for Low Power Node (LPN) mode to save energy.
• Works with Nordic Semiconductor's nRF Mesh mobile app for provisioning and configuration.

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Requirements

Hardware:

• At least two development kits:
  • One for this light switch (client).
  • One or more for the Bluetooth Mesh Light (server).

Software:

• Nordic Semiconductor's nRF Mesh mobile app:
  • Available for Android and iOS.

Hardware used:

• nrf52833 development kit
  • Containes 4 LEDs and 4 buttons

Software used:

• Visual Studio Code
• nrf Connect App
• nrf Mesh App (iOS)

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How It Works

What is Bluetooth Mesh?

Bluetooth Mesh is a network where devices (nodes) communicate with each other. Each node can send and receive messages, making it ideal for smart lighting, home automation, and more.

What Does This Project Do?

This project sets up a Bluetooth Mesh client that:

• Sends On/Off commands to light sources (servers) in the network.
• Uses buttons on the development kit to control the lights.
• Reflects the light status using LEDs on the development kit.

How Does It Work?

1. Provisioning: The device is added to the mesh network using the nRF Mesh mobile app.
2. Configuration: The app sets up how the client (light switch) communicates with the servers (light sources).
3. Control: Pressing a button sends a command to turn a light on or off.

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Low Power Node (LPN) Mode

What is LPN Mode?

LPN mode reduces power consumption by:

• Sleeping most of the time.
• Waking up only to send or receive messages.

How to Enable LPN Mode:

1. Use the overlay-lpn.conf file during the build process.
2. Example build command:

   west build -b <board_target> -p -- -DEXTRA_CONF_FILE="overlay-lpn.conf"
   

LPN Mode Features:

• Button 4 (or Button 3 on some boards) enables Node ID advertisement for 30 seconds.
• After 30 seconds, the device returns to low-power mode.

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Buttons and LEDs

Buttons:

• Used for provisioning and controlling lights.
• Each button is linked to a specific light source.

LEDs:

• Show the status of the lights.
• Blink during provisioning to indicate activity.

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Building and Running

Steps:

1. Make sure Bluetooth Mesh is enabled in your environment.
2. Build the project using the appropriate configuration.
3. Flash the firmware to your development kit.

Example Build Command:

west build -b <board_target>

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Testing

What You Need:

• A smartphone with the nRF Mesh mobile app.
• At least one server device running the Bluetooth Mesh Light sample.

Steps:

1. Provision the light switch using the app.
2. Configure the client and server models.
3. Press buttons on the client to control the lights on the server.

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Power Consumption

Standard vs. LPN Mode:

• Standard mode: Higher power consumption.
• LPN mode: Significantly lower power consumption.

Example Measurements:

Board	Standard Mode	LPN Mode
nrf52dk/nrf52832	7.14 mA	13.69 µA
nrf52840dk/nrf52840	6.71 mA	14.63 µA
nrf52833dk/nrf52833	6.10 mA	14.43 µA

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Dependencies

Nordic Libraries:

• Generic OnOff Client model.
• Device provisioning library.
• Buttons and LEDs library.

Zephyr Libraries:

• Bluetooth Mesh API.
• Kernel API.

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Source Files

main.c:

Handles initialization and Bluetooth setup.

model_handler.c:

Manages the mesh models and button actions.

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Additional Notes

• This project cannot demonstrate functionality on its own. It needs a server device running the Bluetooth Mesh Light sample.
• For detailed configuration options, refer to the overlay-lpn.conf file.