This application report presents the concept of the wireless tree structure using Bluetooth Low Energy technology. The important steps when designing a Bluetooth Low Energy tree structure are elaborated on a detailed level throughout the document. With the use of the TI SimpleLink™ Bluetooth low energy software Stack, the tree structure can be done in a simple and intuitive way.
The accompanying software example can be found on github.
SimpleLink is a registered trademark of Texas Instruments.
Bluetooth is a registered trademark of Bluetooth SIG, Inc.
Zigbee is a registered trademark of ZigBee Alliance.
All other trademarks are the property of their respective owners.
Bluetooth Low Energy is a personal local network technology that is designed and sold by Bluetooth Special Interest Group (Bluetooth SIG). It is aimed at applications in the fields of medical and health care, sports and fitness, beacon, security, family entertainment and so on. Especially in the fields of industry and building automation, Bluetooth Low Energy has very low energy consumption and extensive wireless networking features, so Bluetooth Low Energy has a vast market. The Bluetooth Low Energy tree structure network is an extended topology based on star structure networks. Using a tree structure allows the network to include more nodes and a wider range, which makes the Bluetooth Low Energy suitable for more wireless control and sensor applications.
TI SimpleLink Bluetooth Low Energy CC26x2 wireless microcontroller as a Bluetooth central or peripheral has the ability to connect to a maximum of 32 other Bluetooth Low Energy devices simultaneously, that also makes it possible to use the TI Bluetooth Low Energy solution to build a larger and extendable Bluetooth Low Energy network. A tree structure network based on SimpleLink CC26x2 wireless MCU is proposed and analyzed in this application report.
According to the Bluetooth Low Energy Core Specification, there are two roles defined (GAPRoles) when the Bluetooth Low Energy connection is established. The node that initiates the connection defined as the Central device and the node that is connected to by the Central is defined as the Peripheral device.
There are several parameters that are important for the Bluetooth Low Energy connection, two of them are connection interval and slave latency. The connection interval determines how often the central asks for data from the peripheral. The slave latency represents the number of times the peripheral can choose not to answer when the central asks for data. The connection interval and slave latency typically affect the performance of a Bluetooth Low Energy link the most. For example, the lower the slave latency and faster the connection interval, the faster the effective data transfer rate between the peripheral and central. On the other hand, this also leads to a higher average current consumption since the devices use their radio more often than at a longer connection interval.