Bluetooth: Mesh OnOff Model

Overview

This is a simple application demonstrating a Bluetooth mesh multi-element node. Each element has a mesh onoff client and server model which controls one of the 4 sets of buttons and LEDs .

Prior to provisioning, an unprovisioned beacon is broadcast that contains a unique UUID. It is obtained from the device address set by Nordic in the FICR. Each button controls the state of its corresponding LED and does not initiate any mesh activity.

The models for button 1 and LED 1 are in the node’s root element. The 3 remaining button/LED pairs are in elements 1 through 3. Assuming the provisioner assigns 0x100 to the root element, the secondary elements will appear at 0x101, 0x102 and 0x103.

After provisioning, the button clients must be configured to publish and the LED servers to subscribe.

If a LED server is provided with a publish address, it will also publish its status on an onoff state change.

If a button is pressed only once within a 1 second interval, it sends an “on” message. If it is pressed more than once, it sends an “off” message. The buttons are quite noisy and are debounced in the button_pressed() interrupt handler. An interrupt within 250ms of the previous is discarded. This might seem a little clumsy, but the alternative of using one button for “on” and another for “off” would reduce the number of onoff clients from 4 to 2.

Requirements

This sample has been tested on the Nordic nRF52840-PDK board, but would likely also run on the nrf52_pca10040 board.

Building and Running

This sample can be found under samples/boards/nrf52/mesh/onoff-app in the Zephyr tree.

The following commands build the application.

Using west:

west build -b nrf52840_pca10056 samples/boards/nrf52/mesh/onoff-app
west flash

Using CMake and ninja:

cmake -B build -GNinja -DBOARD=nrf52840_pca10056 samples/boards/nrf52/mesh/onoff-app
ninja -C build
ninja -C build flash

Prior to provisioning, each button controls its corresponding LED as one would expect with an actual switch.

Provisioning is done using the BlueZ meshctl utility. Below is an example that binds button 2 and LED 1 to application key 1. It then configures button 2 to publish to group 0xc000 and LED 1 to subscribe to that group.

discover-unprovisioned on
provision <discovered UUID>
menu config
target 0100
appkey-add 1
bind 0 1 1000                # bind appkey 1 to LED server on element 0 (unicast 0100)
sub-add 0100 c000 1000       # add subscription to group address c000 to the LED server
bind 1 1 1001                # bind appkey 1 to button 2 on element 1 (unicast 0101)
pub-set 0101 c000 1 0 0 1001 # publish button 2 to group address c000

The meshctl utility maintains a persistent JSON database containing the mesh configuration. As additional nodes (boards) are provisioned, it assigns sequential unicast addresses based on the number of elements supported by the node. This example supports 4 elements per node.

The first or root element of the node contains models for configuration, health, and onoff. The secondary elements only have models for onoff. The meshctl target for configuration must be the root element’s unicast address as it is the only one that has a configuration server model.

If meshctl is gracefully exited, it can be restarted and reconnected to network 0x0.

The meshctl utility also supports a onoff model client that can be used to change the state of any LED that is bound to application key 0x1. This is done by setting the target to the unicast address of the element that has that LED’s model and issuing the onoff command. Group addresses are not supported.

This application was derived from the sample mesh skeleton at samples/bluetooth/mesh.

See bluetooth samples section for details.