Silicon Labs UG235.02 User manual
UG235.02: Using Silicon Labs Connect
v2.x with IEEE 802.15.4
This chapter of the Connect v2.x User’s Guide describes how to
use the Silicon Labs Connect stack v2.x with IEEE 802.15.4. The
Connect v2.x User’s Guide assumes that you have already installed the Simplicity Studio development environment and the Flex
SDK, and that you are familiar with the basics of configuring,
compiling, and flashing Connect-based applications. Refer to
UG235.01: Developing Code with Silicon Labs Connect v2.x for
an overview of the chapters in the Connect v2.x User’s Guide.
The Connect v2.x User’s Guide is a series of documents that provides in-depth information for developers who are using the Silicon Labs Connect Stack for their application
development. If you are new to Connect and the Proprietary Flex SDK, see QSG138:
Proprietary Flex SDK v2.x Quick Start Guide.
Proprietary is supported on all EFR32FG devices. For others, check the device's data
sheet under Ordering Information > Protocol Stack to see if Proprietary is supported. In
Proprietary SDK version 2.7.n, Connect is not supported on EFR32xG22.
KEY POINTS
• Introduction to common terms used in
IEEE 802.15.4
• IEEE 802.15.4 frame formats
• IEEE 802.15.4 security
• Common processes in IEEE 802.15.4
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UG235.02: Using Silicon Labs Connect v2.x with IEEE 802.15.4
Introduction
1. Introduction
Silicon Labs Connect is based on the IEEE 802.15.4-2011 standard (abbreviated to IEEE 802.15.4). Therefore, to understand the Silicon Labs Connect stack, you also need a basic knowledge of 802.15.4 which defines various Physical and Media Access Control layers
that are designed for low-data rate, low-power, and low-complexity, short-range communications in Personal Area Networks. IEEE
802.15.4 is also the basis of mesh network protocols such as Zigbee® or Thread.
This document provides a short introduction to the IEEE 802.15.4 features that are used in Connect so you can understand its MAC
layer without having to read the IEEE 802.15.4 specification.
For more information about IEEE 802.15.4, see https://standards.ieee.org/standard/802_15_4-2011.html.
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UG235.02: Using Silicon Labs Connect v2.x with IEEE 802.15.4
Basic Terms
2. Basic Terms
It is important to define some common terms before delving into the technical details.
2.1 Physical Layer
The Physical (PHY) layer is the lowest layer in a communication stack. It is responsible for the transmission of unstructured data
through a medium. In a wireless networking stack, the PHY defines the modulation, bit rate, and parts of the frame that are required for
successful data reception (for example, the preamble and sync word).
2.2 Data Link Layer
The Data Link Layer (DLL) is built on top of the PHY in a communication stack. It is responsible for reliable data transfer between two
devices (for example, addressing, acknowledgement and integrity checks). In IEEE 802 protocols, the DLL is built up from two layers.
The lower one is called the Media Access Control (MAC) layer. Because IEEE 802.15.4 does not have the upper DLL, the MAC layer is
interchangeable with DLL.
2.3 Personal Area Network
A Personal Area Network (PAN) is a logical group of devices that can communicate with each other. Protocols built on IEEE 802.15.4
usually communicate inside a PAN.
2.4 PAN Coordinator
The PAN coordinator can perform special services in some protocols (for example, allocating short addresses).
2.5 Intra-PAN Message
An intra-PAN message is one where the source and destination device are in the same PAN.
2.6 Inter-PAN Message
An inter-PAN message is one where the source and destination device are in different PANs.
2.7 Long Address
A long address is a globally unique 64-bit address (EUI64). Each Silicon Labs Wireless Gecko is assigned an EUI64 address at the
factory. This is standardized across most IEEE 802 protocols (for example, IPv6 uses the same EUI64 as the MAC address).
2.8 Short Address
A short address is a 16-bit address that is only unique in a PAN. Because IEEE 802.15.4 has a fairly short frame, using long addresses
would consume a lot of the frame. Therefore, devices can use short addresses if they also know the PAN ID. 0xFFFE is a reserved
special address, which means the device is in the PAN, but does not have a source address and it should use its long address to communicate.
2.9 PAN ID
A PAN ID is a 16-bit long address that identifies a PAN. There is no standardized way to allocate PAN IDs so the application should
make sure to use a PAN ID that is not used in the same network.
2.10 Broadcast Address
A broadcast address is special address that should be received by any device. The 0xFFFF short address is the broadcast short address. The 0xFFFF PAN ID is the broadcast PAN ID.
2.11 CSMA/CA
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a "listen-before-talk" protocol: To avoid collisions, the radio listens to a channel before transmission. If the channel is "free" (that is, nothing was received), the device can transmit. If the channel is
"busy" (that is, something was received), the device waits before trying again. After a certain number of retries, the transmit will fail and
an error will be reported to the application.
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