Getting Started with Connect Stack
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Silicon Labs is developing products designed to meet the demands of customers as we move to an ever-connected world of devices in the home, what is often referred to as the IoT (Internet of Things). At a high level the goals of IoT for Silicon Labs are to:
- Connect all the devices in the home with best-in-class mesh networking, whether with Ember ZigBee PRO or other emerging standards.
- Leverage the company's expertise in low-power, constrained devices.
- Enhance established low-power, mixed-signal chips.
- Provide low-cost bridging to existing Ethernet and Wi-Fi devices.
- Enable cloud services and connectivity to smartphones and tablets that promote ease of use and a common user experience for customers.
Achieving all of these goals will increase adoption rates and user acceptance for IoT devices in the Connected Home.
One such challenge is managing devices requiring low power consumption, such as battery-powered devices where long battery life is essential. To meet this challenge Silicon Labs has developed the Silicon Labs Connect stack. Connect provides a fully-featured, easily-customizable wireless networking solution optimized for devices that require low power consumption and are used in a simple network topology. Connect is configurable to be compliant with regional communications standards worldwide. Each RF configuration is designed for maximum performance under each regional standard.
The Silicon Labs Connect stack supports many combinations of radio modulation, frequency and data rates. The stack provides support for end nodes, coordinators, and range extenders. It includes all wireless MAC (Medium Access Control) layer functions such as scanning and joining, setting up a point-to-point or star network, and managing device types such as sleepy end devices, routers, and coordinators. With all this functionality already implemented in the stack, users can focus on their end application development and not worry about the lower-level radio and network details.
The Connect stack should be used in applications with simple network topologies, such as a set of data readers feeding information directly to a single central collection point (star or extended star topology), or a set of nodes in the same range exchanging data in a single-hop fashion (direct devices or MAC devices). It does not provide a full mesh networking solution such as that provided by the EmberZNet PRO or Silicon Labs Thread stacks.
The Connect stack is part of the Silicon Labs Flex SDK (Software Development Kit), installed through Simplicity Studio. Connect runs on top of RAIL (Radio Abstraction Interface Layer), also included with the Flex SDK. RAIL provides an intuitive, easily-customizable radio interface layer that is designed to support proprietary or standards-based wireless protocols. For more information, see UG103.13: RAIL Fundamentals.
The Connect stack supports efficient application development through its “building block” plug-in design. When used with the Simplicity Studio IDE (Integrated Development Environment), developers can easily select the functions that should be included in the application. The resulting applications are completely portable, in that they can be recompiled for different regions, different MCUs, and different radios.
The Connect stack supports the following device types:
- Star coordinator: The star coordinator forms and manages the star or extended star network. The star coordinator also communicates with other range extenders and end nodes. Each Connect star network has a single coordinator.
- Star range extender: A device between the star coordinator and one or more star end nodes that can be used to extend the range of the star end nodes. Each range extender can serve up to 32 star end nodes.
- Star end node: Joins to a star coordinator or a star range extender.
- Direct device: A device able to send and receive messages from other (direct) devices in range on the same PAN, with no star topology restrictions. Such a device does not relay messages.
- MAC device: A device able to send and receive standard 802.15.4 messages from other 802.15.4 devices in range. Such a device does not relay messages.
The Connect stack supports three topologies, shown in the figure below:
- Point to Point
- Extended Star
- Single Hop Direct
- Single Hop MAC
A Point to Point network provides simple communications between two devices: a star coordinator (blue node) and a star end node (white node).
A Star network has a single star coordinator hub communicating with multiple star end nodes. All communication is through the star coordinator.
An Extended Star network includes a star range extender (red node) between the star coordinator and star end node(s) in one or more arms of the star. Communications between the star coordinator and the far star end node(s) flow through one of the star range extenders.
A Single Hop Direct or MAC network includes two or more direct nodes (green node) communicating with each other in a single hop fashion.
The Connect stack provides code organized into three functional layers, as shown in the following figure:
- PHY (physical)
The PHY and MAC layers are based on the IEEE 802.15.4-2011 standard IEEE 802.15.4-2011 Specification.
The Network layer is based on a proprietary protocol.
Finally, the Connect Application Framework provides a complete tool and API infrastructure over the underlying stack layers. Functionality within the Application Framework and the Connect stack layers is provided in the form of individual building blocks called plugins. Details of the plugins for each layer are provided in the Silicon Labs Connect Application Framework API Reference included in the stack documentation.
For more information about Connect Stack, see UG103.12.