SILICON LABS Multi Instance Open Thread Support User Guide

SILICON LABS Multi Instance Open Thread Support

USER GUIDE

This section describes how to enable multi-PAN support for OpenThread SoC applications through the use of multiple OpenThread instances. By default, OpenThread is configured to support a single instance per device.

Enabling multiple instances allows a single device to participate in multiple independent Thread networks simultaneously, which is useful for scenarios requiring network isolation or concurrent operation of separate Thread networks.

Key Points

• Understanding multiple OpenThread instances.
• Build configuration requirements.
• Application code modifications.

Understanding Multiple OpenThread Instances

OpenThread supports running multiple independent instances on a single SoC device. Each instance operates as a separate Thread network stack with its own:

• Network configuration and credentials.
• Thread network state.
• Routing tables.
• Security keys and certificates.
• Network buffers and memory resources.

This multi-instance capability enables scenarios such as:

• Participating in multiple Thread networks simultaneously.
• Network isolation for security or testing purposes.
• Gateway applications connecting different Thread networks.

Comparison With Multi-PAN RCP

In a multi-instance SoC application, multiple OpenThread network stacks run concurrently on a single SoC device, enabling it to participate in several independent Thread networks using local resources.

In contrast, a multi-PAN RCP (Radio Co-Processor) configuration allows a host processor to control multiple IEEE 802.15.4 networks by connecting to a single RCP, where the RCP itself does not manage network state but instead provides radio services for multiple networks managed by the host. Typically, this configuration is intended to manage a Zigbee and a Thread network, but multiple Thread networks are architecturally possible.

The key distinction is that multi-instance is handled fully on the SoC, whereas multi-PAN RCP splits network management between the host and the RCP.

Prerequisites

Before enabling multiple OpenThread instances, ensure that:

• Sufficient memory and processing resources are available (see Memory Comparison for details).
• You are using a compatible version of the Silicon Labs OpenThread SDK.
• Simplicity Studio is installed and configured.

Enabling Multiple Instances in Build Configuration

Using Simplicity Studio

1. Open your OpenThread project in Simplicity Studio.
2. Navigate to the Software Components tab.
3. Open the configuration for the selected OpenThread Stack, and enable the following options:

• 1. Multiple OpenThread Instances
• 2. Multiple Static Instance Support
• 3. Set Number of OpenThread Instances to the desired number of instances

4. If running instances on separate channels, enable the following, under RAIL_IEEE802154_OPTIONS: (Platform > Radio):

• 1. RAIL Utility, IEEE802.15.4 Fast Channel Switching Configuration
• 2. RAIL Utility, DMA

5. Generate and build your project.

Using Command Line Build

If building from the command line, add the following configuration options:

• OPENTHREAD_CONFIG_MULTIPLE_INSTANCE_ENABLE:1
• OPENTHREAD_CONFIG_MULTIPLE_STATIC_INSTANCE_ENABLE:1
• OPENTHREAD_CONFIG_MULTIPLE_INSTANCE_NUM:\<number of instances\>

If running instances on separate channels, add the following to enable channel switching support:

Add the following configuration option:

• SL_RAIL_UTIL_IEEE802154_FAST_CHANNEL_SWITCHING_DEFAULT_ENABLED:1
• Generate your project with the following components:
• sl_rail_util_ieee802154_fast_channel_switching
• sl_rail_util_dma

Application Code Modifications

After enabling multiple instances in the build configuration, update your application code to create and manage multiple OpenThread instances.

API Changes

• Use otInstanceInitMultiple to initialize multiple instances rather than otInstanceInitSingle .
• Use otInstanceGetIndex to retrieve the index of a provided instance pointer.
• Use otInstanceGetInstance to retrieve the instance pointer associated with a provided index.

Example: Multi-Instance CLI Sample Application

To help you get started, we provide a ready-to-use sample application and a utility component designed specifically for multi-instance OpenThread development:

Sample App: OpenThread – SoC CLI (FTD multi-instance)
This sample demonstrates how to build and use a CLI-based app that manages and interacts with multiple
Thread instances.

Multi-Instance CLI Utility Component: OpenThread | Multi-Instance CLI Support

This component provides support for CLI control of multiple OpenThread instances by adding an instance CLI user command set to the OpenThread CLI interpreter, which can perform the following operations:

List initialized instances, their static index, and their id value.
Print the index of the instance that the CLI is controlling.

Reset the CLI context to operate on a different instance of a specified index.

Using the CLI with Multiple Instances:

The sample application initializes 2 instances and sets the CLI to operate on instance 0. The following shows a representative interaction with forming a network on each instance using the CLI:

Topology Examples

The diagrams below represent how multi-PAN SoC devices can interact with single instance SoC devices as well as other multi-PAN SoC devices.

A single multi-instance device communicating with single instance devices over separate PANs and channels:

Two multi-instance devices communicating with each other across two independent connections:

Configuration Considerations

Network Configuration

Each OpenThread instance must be configured with unique network parameters:

Extended PAN ID: Each instance should use a different Extended PAN ID.
Network Key: Each instance requires its own network key.
Channel: Instances can operate on the same or different channels.
PAN ID: Each instance should have a unique PAN ID if operating on the same channel.

Platform Limitations

Some platforms may have limitations when running multiple instances:
Platform constraints may limit the number of concurrent instances to no more than 3.
Multi-instance support limited to statically initialized instances with key references enabled.

Memory Comparison

Enabling multi-instance support will require more RAM and use more code size than a single instance application. While the exact difference will vary based on the specific OpenThread configuration values used, here is a relative comparison between applications with a comparable FTD configuration:

Measurement Details:

• SDK release: sisdk-2025.12
• Target part: EFR32MG24
• Link Time Optimization (LTO): Enabled

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