Simple Mesh Node

Table of Contents

• Introduction
• Hardware Prerequisites
• Software Prerequisites
• Menu Usage
  • Init menu
  • Button Menu
  • Led Menu
  • Example - Turn on a Led
  • Generic models Menu
  • Sensor models Menu
• Host PC Tool Usage
• BLE Mesh
  • Overview
  • High Level System Architecture
    • Mesh Profile
    • Zephyr Project
  • TI BLE Stack & Zephyr
  • Changing Profile Configurations

Introduction

The simple_mesh_node project implements a simple Bluetooth Low Energy Mesh device with Mesh functionality.
The application can be controlled in 2 ways:

• Using a menu, controlled by two buttons.
• Using an external Host PC tool (Python script), sending messages over UART.

For information about BLE-Mesh configuration via SysConfig please refer to the BLE Mesh SysConfig Features section in the BLE5-Stack User's Guide provided in the SDK.

This project has the following app configurations available:

App Build Configuration	Description
Release (default)	All TI-RTOS debug features disabled but application-logging to UART remains enabled. The application uses the config file ble_release.cfg and the defines are in <app name>_Release.opt.
Debug	All TI-RTOS debug features enabled. The application uses the config file ble_debug.cfg and the defines are in <app name>_Debug.opt.

All application configurations use the stack library configuration, FlashROM_Library. This build configuration will yield additional flash footprint optimizations by the linker since the application and stack can share contiguous flash pages. This configuration is further discussed in the Stack Library Configuration section of the BLE5-Stack User's Guide provided in the SDK.

Hardware Prerequisites

The default Simple Mesh Node board configuration uses the device's LaunchPad development kit. This hardware configuration is shown in the below image:

For custom hardware, see the Running the SDK on Custom Boards section of the BLE5-Stack User's Guide.

Software Prerequisites

For information on what versions of Code Composer Studio and IAR Embedded Workbench to use, see the Release Notes file provided in the SDK. For information on how to import this project into your IDE workspace and build/run, please refer to the device's Platform section in the BLE5-Stack User's Guide.

Menu Usage

This application uses the UART peripheral to provide an interface for the application. The UART is only used for display messages.

This document will use a terminal program (Tera Term, PuTTY, etc.) to serve as the display for the output from the LaunchPad. Note that any other serial terminal can be used. The following default parameters are used for the UART peripheral display:

UART Param	Default Values
Baud Rate	115200
Data length	8 bits
Parity	None
Stop bits	1 bit
Flow Control	None

Once the Simple Mesh Node sample application starts, the output to the terminal will report its address and that it is initialized and ready to begin discovery, as shown below. On the menu, you can use the left button (BTN-1) to move to the next option and the right button (BTN-2) to select an item:

Main Menu

First lines are for the 5 sub-menus: INIT, BUTTON, LED, GENERIC models and SENSOR models
Middle lines are for the status of the messages between devices.
Last lines are for the Button, Led, Generic models and Sensor models status

• Menu limitation: when confiugred to static provisioning, the node can comunicate with up to 10 other nodes
• The default node configuration is basic mesh functionallity+RELAY+PROXY.
  
• User must set a different UUID for each node.
  The device UUID is configured in SysConfig under BLE → BLE Mesh → Provisioning Data Configuration before compiling the project

Init Menu

The Mesh Init menu contains 2 options to initialize the mesh device:

• With unprovisioned beacon
  
• Load from the Non-Volatile Storage (NVS) the address and provisioning info stored from previous run.
  

When static provisioning is enabled via SysConfig, the unprovisioned beacon option will be replaced with the static provisioning option.

Note: The device address is configured via SysConfig.
The provisioning information that the node will be loaded with, can be updated in the static_prov.c/h files.

Button Menu

The second option that can be selected is the BUTTON menu.
The BUTTON menu contains options to turn on and off a LED on a selected target device.
The menu also enables getting the status of the LED on the target device.
User can first set button target address, range = [Group, 1..10], default=Group (all nodes)

Note: Turn on the LED is not real led on device board
It is only status line ----LED ON---- in the device terminal

Led Menu

The third option that can be selected is the LED menu.
The LED menu contains an option to notify the status of a LED on selected target device.
User can first set led target address, range = [Group, 1..10], default=Group (all nodes)

Example - Turn on a Led

Sending Turn LED ON from Node #1 to Node #2.
As can be seen in the picture below, in the LED status line (buttom line) in Node #2, after sending the request, the status of the LED is ON

Mesh models

Generic models Menu

The GENERIC models menu contains the following models sub-menus (client and server):

    - ONOFF         get, set, set_unack
                    set values 0, 1 (default 0)
                    several timing settings used for qualification testing
                                (default transition time=0, delay=0)
    - LEVEL         level get, set, set_unack
                    delta set, set_unack
                    move  set, set_unack
                    several level value (default 0x01FF) and timings used for qualification testing
                                (default transition time=0, delay=0)
    - TRANSITION    get, set, set_unack
                    several timing values used for qualification testing (default transition time=0)
    - POWER ONOFF   get, set, set_unack (ON, OFF, Restore)
    - BATTERY       get

User can first set the target address, range = [Group, 1..10], default=1

Sensor models Menu

The SENSOR models menu contains Client, Server and Set target address sub-menu.
User can first set the target address, range = [1..10], default=1

Sensor Client models Menu

The SENSOR Client models menu contains Client command for the following states:

    Descriptor - get
    Data       - get
    Column     - get
    Series     - get
    Settings   - get
    Cadence    - get, set, set_unack
    Setting    - get, set, set_unack

User should first select the Property id:

    tmpr8 - id of the temperture sensor implemented in this sample
    0x42  - id of unimplemented sensor, used for qualification testing
    all   - id used to send command for all sensors

Host PC Tool Usage

In order to work with the Host PC tool, the user must enable the Network Processor Mode via SysConfig (Under BLE).

When Network Processor Mode is enabled, the provisioning data and composition data configuration is done on the host side (and not via SysConfig).
For more information, please refer to the TI Bluetooth Mesh Host PC Tool section in the BLE5-Stack User's Guide provided in the SDK.

BLE Mesh

Overview

A general mesh network has a many-to-many topology, where each device is able to communicate with every other device in the mesh network. Communication is achieved using messages, and devices are able to relay messages to other devices so that the end-to-end communication range is extended far beyond the radio range of each individual node.

Basic communication over mesh network is based on flooding, where each node, acting as a relay node, forwards a message which has been received and not designate to the local node. Managed flooding, where time to live and message caching mechanisms are implemented, is used to reduce the flooded traffic over the network. Enhanced implementations include management of forward paths to further optimize the forwarded traffic load.

The Mesh support over BLE networks is standardized by the SIG in the Bluetooth Mesh Profile specification and defines fundamental requirements to enable an interoperable mesh networking solution for Bluetooth low energy wireless technology.

High Level System Architecture

Mesh Profile

Starting from the bottom up, the BLE Mesh standard(Mesh Profile) enables overlay of a complete protocol stack on top of a BLE protocol stack, with the last providing bearer services to carry connection-less (as advertisement bearers) or connection-oriented (as GATT bearers) based connectivity. At the GATT bearers level, the BLE Mesh is seen as a profile where attributes are used to exchange mesh data.

The Mesh layer architecture:

The BLE Mesh network topology is built of different mesh nodes types (features):

• Mesh node: A member of a mesh network. It includes basic node functionality for receiving and processing broadcast, multicast and uni-cast message designate for the node as well as transmission of local mesh data.
• Mesh Relay node: Local processing as well as mesh messages relaying for range extension within a mesh network (Multiple hops support).
• Mesh Proxy node: Proxying between GATT-Bearer and Advertise bearer, for devices that support GATT-bearer only (i.e. Mobiles phones, etc.).
• Mesh Low power node: A power limited node which wakes up on specific time intervals to send messages or receive messages which are aggregated by a friend node.
• Mesh Friend node: Used to aggregate messages for LPN nodes during their sleep cycles and deliver their messages upon wake-up.

Node combinations are allowed over same device. For instance: Friend and Relay node.

An example Mesh network:

For further reading about the Mesh , please refer to the Mesh Networking Specifications on the Bluetooth SIG webpage.

Zephyr Project

The Texas Instruments mesh solution utilizes the open source code kindly provided by the Zephyr Project atop the TI BLE protocol stack.
The Zephyr Project is a community project managed by the Linux Foundation. The source code can be found on Github.

TI BLE Stack & Zephyr

The following diagram shows the top level architecture in which the application, the Mesh profile, the adaptation layer and the BLE stack co-exist:

Changing Profile Configurations

As mentioned before in the Mesh Profile section, there are numerous Mesh capabilites. The node's capabilities are configured via SysConfig under BLE → BLE Mesh.