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The Many Flavors of Bluetooth IoT Connectivity

The Many Flavors of Bluetooth IoT Connectivity.png

Introduction

The market for wirelessly connected Internet of Things (IoT) devices is expected to grow explosively over the next few years, so developers are rushing to find the best platforms and tools with which to build their systems. But making the right choices can be challenging. Connectivity options include Classic Bluetooth and Bluetooth Smart (also called Bluetooth Low Energy or BLE) for point-to-point, Wi-Fi for IP gateways, or ZigBee and Thread for mesh networks that enable machine-to-machine connections.

The fastest growing segments of the IoT are personal area networking (PAN) apps that give humans access to and control of the devices in their immediate environment or that they wear on their bodies. Because the protocol is already incorporated into virtually every mobile and smartphone, Bluetooth is the fastest and least expensive route to accomplish this objective. It provides users with a familiar and convenient connectivity option, and developers with a familiar set of building blocks.

Bluetooth allows developers to build IoT systems across a variety of applications and do so in the most costeffective manner on a platform flexible enough to meet varying operating constraints.

 

Bluetooth’s IoT Building Blocks

Bluetooth was originally developed as a wireless alternative to RS-232 data cables and point-to-point audio. Now managed and directed by the Bluetooth Special Interest Group (SIG), Bluetooth has evolved into a point-tomultipoint protocol typically supporting a few end-nodes on the same domain and operating over the 2.4 to 2.485 GHz spectrum to provide direct connections between two or more nodes – usually an end user and a “thing” to be controlled or interrogated. In Version 4.0, the standard was extended to support Bluetooth Smart as well as devices that can operate with Bluetooth Classic and also in BLE mode. Bluetooth 4.2 also introduced higher data rates with extended packet sizes as well as TCI/IP connectivity, making Bluetooth a great candidate for accessing networks seamlessly via access points among mobile phones.

Bluetooth Smart was incorporated into the main Bluetooth standard in 2010 with the adoption of the Bluetooth Core Specification Version 4.0 and operates over the same spectrum as Classic Bluetooth but uses it somewhat differently. Bluetooth Smart is designed to provide considerably reduced power consumption and cost while maintaining a similar communication range. Instead of the Classic Bluetooth specification's 79 1 MHz channels, Bluetooth Smart supports 40 2 MHz channels.

While Bluetooth Smart has been limited to bit rates of up to 1 Mbit/s, with a maximum transmit power of +10 dBm, Bluetooth Classic is capable of 4 Mbit/s and +20 dBm. Although Bluetooth Smart is not backward-compatible with Classic, the Bluetooth 4.0 specification permits devices to implement either or both of the Smart and Classic systems. There has been decision in the Bluetooth SIG to allow +20 dBm transmit output power for Bluetooth Smart. When this becomes a reality, Silicon Labs is uniquely positioned to meet this requirement with Blue Gecko SoCs and modules that natively support up to +19.5 dBm output power. Bluetooth Smart is evolving even further and the 5.0 specification will significantly improve the receiver sensitivity increasing the link budget to (approximately 120 dB) levels Silicon Labs modules and SoC will reach over a half a mile range.

 

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