More efficient and safer Bluetooth 5.0 design

The launch of the Bluetooth Mesh networking standard, which connects thousands of small devices together through IoT solutions, has attracted a lot of attention. STMicroelectronics Bluetooth SoC users can migrate to the new standard through a simple firmware update. Therefore, it is necessary to take a closer look at this flagship SoC (BlueNRG-2), its technical issues and product advantages. Like its predecessor, the BlueNRG-1, the latest SoC uses a Cortex-M0 core and 24 kB of RAM, but integrates a larger flash memory (upgraded from 160 kB to 256 kB) and complies with the Bluetooth 5.0 standard.

The industry is very focused on the Bluetooth 5.0 specification and what the new technology means. Manufacturers must have a clear understanding of the features they need to implement to pass Bluetooth 5.0 certification and focus on developing the best features for their products. For ST, the first thing to do is to ensure pin compatibility between BlueNRG-1 and BlueNRG-2. We must ensure that engineers can easily switch between the two with minimal changes to the code base to help them determine which solution makes the most sense for their design.

Our team also incorporated three key features (Data Length Extension, Secure Connections, and Bluetooth Smart Privacy 1.2) into the BlueNRG-2 SoC to obtain Bluetooth 5.0 certification.

Faster and more practical

Our SoC is focused on low power applications. If broadcasting once per second, the average current consumption of the device is only 15.12µA , and using a simple 230 mAh CR2032 button battery, the device can last for one year, eight months and 28 days. However, to support data length extension, our engineers still improved the RF and its performance.

Compared to BlueNRG-1, the transmission rate of BlueNRG-2 has increased from 200kbps to 600kbps. The software protocol stack has also been updated so that developers can get started quickly and implement RF updates more easily. In addition, the new QFN48 package provides 26 programmable GPIOs, while the previous QFN32 package only provides 15 programmable GPIOs, which allows developers to better optimize the use of the latest SoCs.

Bluetooth 5.0 security features

We also work to ensure the security of connections and data transmission. Therefore, the low-power mode of BlueNRG–2 is compatible with secure connections, and the Bluetooth SIG (technology alliance) has adopted a new FIPS-compliant cryptographic mode, a federal information processing standard issued by the National Institute of Standards and Technology (NIST) in the United States, in compliance with the Federal Information Security Management Act. In this case, the new standard prevents key sniffing. BlueNRG–2 also optimizes performance and improves protection against low-level attacks by integrating specific hardware to accelerate cryptographic operations in ECC-256 and AES–128 CCM modes.

BlueNRG-2 also supports Bluetooth Smart privacy 1.2, which is used to prevent hackers from tracking users' MAC addresses. The MAC address is like a serial number for Ethernet, Wi-Fi or Bluetooth modules, etc. Since it is unique to a device, people can track your MAC address and potentially track your activities when you connect to a Wi-Fi access point or when you pair your device with a car or smartphone. Bluetooth Smart privacy prevents inappropriate intrusions on user privacy by replacing the Bluetooth MAC address with a random value at regular intervals or when triggered by specific events (such as turning the device on and off, making it impossible to track people's activities).

Create a Bluetooth 5.0 device now

The easiest way to start prototyping with BlueNRG–2 is to use the STEVAL-IDB008V2 expansion board, which integrates ST’s balun (BALF-NRG-02D3). The expansion board also includes a 3D digital accelerometer and gyroscope (LSM6DS3) and a barometric pressure sensor with an embedded thermometer (LPS25HB), helping developers get started with their IoT applications.

STEVAL-IDB008V2 expansion board

Finally, in addition to the STSW-BNRG-Mesh software package, the STEVAL-IDB008V2 is also compatible with the STSW-BLUENRG1-DK software package, which contains drivers, a radio initialization wizard, libraries, and BlueNRG–1 and BlueNRG-2 application examples, further simplifying the development process. This can help anyone with a basic understanding of RF to generate the correct configuration files. Engineers can also review our use cases and customize them to their needs. The SoC is then programmed using a UART bootloader. As long as a similar design is used, developers can keep most of their code when converting to a custom PCB.

Related previous articles:

How to choose low-power Bluetooth

BlueNRG-1&2 Development Environment Setup (I) Overview

BlueNRG-1&2 Development Environment Construction (Part 2) DK Package

Building the BlueNRG-1&2 Development Environment (Part 3) Current Evaluation Tool

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