Bluetooth 5 Technology for the Internet of Things

Bluetooth 5 offers a long range, high speed and extended support for connectionless services. This opens up new IoT applications for the smart environment.

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MicroConsult Microelectronics Consulting & Training GmbH

ROHM Semiconductor GmbH

NetModule AG

The move from Bluetooth 4.2 to Bluetooth 5 allows companies and developers to bring about an accessible, interoperable Internet of Things. The new standard specifies modes with four times the range of existing devices by reducing the data rate to 500 Kbps and 250 Kbps to allow more sensors to be used reliably around the home.

This range not only allows more distance between a controller and a sensor, but also provides a more robust link for the end devices. It also allows for twice the data rate to 2 Mbps to allow for higher quality audio streaming from monitors or to wireless speakers to improve the user experience.

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Bluetooth Will Be in One-Third of All IoT Devices by 2020

Market research estimates that Bluetooth will be in more than one-third of all installed IoT devices by 2020, driven by the ubiquitous implementation in smartphones to act as controllers. However, the requirement for a Bluetooth 5 chip in a smartphone as the controller or for streaming to a wireless headset is very different from the requirements for the Internet of Things. These IoT applications also need more sophisticated power management to maximize the battery life of the system, so an optimized DC-DC converter is an increasingly common element of the SoC.

The designs now being delivered to chip designers accommodate the requirements of SoC devices for IoT. For example, the RivieraWaves Bluetooth IP platform consists of a hardware baseband controller, a digital modem, and a detailed software protocol stack. The stack encompasses the Link Layer up to the GAP/GATT plus a set of Services and Profiles. The Riviera technology has already been used for previous generations of Bluetooth 4.2 devices from NXP such as the MKW31Z256.

The hardware baseband controller is provided as a Verilog IP package. It performs packet encoding/decoding and frame scheduling, and is complemented by a hardware AES128 encryption engine. The software stack is provided as a C code IP package with the Link Layer, L2CAP, ATT, SMP, GAP/GATT, services and profiles that can be modified by the chip developer.

The BLE mode differs from the Bluetooth dual mode, where the protocol stack includes an industry standard HCI interface in the smartphone. A flexible radio interface allows the platform to be deployed with either one of the RivieraWaves RF IPs or various partners' RF IPs enabling optimal selection of foundry and process node.

Another IP supplier, Mindtree, has worked with Texas Instruments to put the Bluetooth 4.2 stack onto the CC1350 processor. This combines a flexible low-power RF transceiver with a 48 MHz ARM® Cortex®-M3 microcontroller that is designed for multiple physical layers and RF standards, making an upgrade to Bluetooth 5 relatively simple. The 2 Mbps GFSK modulation scheme for the radio enables significant improvement in system throughput for users, and is relatively simple to implement in hardware.

The stack is run on a dedicated Cortex-M0 as the radio controller that handles the low-level RF protocol commands that are stored in ROM or RAM. Sensors for the Internet of Things can be handled by a dedicated, autonomous, ultra-low-power controller that can be configured to handle analog and digital sensors, allowing the main Cortex-M3 core to remain in sleep mode. The power, clock management, and radio systems require specific configuration and handling by software to operate correctly, which has been implemented in a dedicated real-time operating system (TI-RTOS). This would also be updated to include the new functionality of Bluetooth 5. This includes the extension of the advertising packets to 237 bytes, which opens up data channels for advertisement, and also introduces the concept of periodic advertisement.

Mindtree has also worked with Synopsys to develop a complete Bluetooth Smart IP design for 4.2 on TSMC's 55 nm and 180 nm processes. This combines the Synopsys physical IP with Mindtree's BlueLitE link layer and software stack IP, providing chip designers with a complete BLE block that minimizes risk and integration challenges for ultra-low-power system-on-chips (SoCs) for IoT applications. Synopsys' PHY IP operates below a one volt supply to extend battery life, and has an integrated antenna-matching network to ensure proper signal transmission between antenna and source, reducing external component cost.

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