Secure Bluetooth LE adoption on rise in automotive applications

With a developed ecosystem, an ultra-low-power consumption profile, and an established presence in mobile phones, it is understandable why Bluetooth Low Energy (Bluetooth LE) technology has emerged as the preferred wireless protocol for new connectivity use cases in automotive applications.

This article examines the drivers behind the rising use of wireless connectivity in automobiles and reviews some current and potential future use cases for Bluetooth LE.

BLE driving factors in vehicles

The automotive industry is undergoing an unprecedented revolution, with a near-simultaneous convergence in the trends toward electrification, autonomous driving, and vehicle-to-everything (V2X) connectivity. Cars are evolving from providing an essential transport service to providing occupants with a rewarding travel experience. Vehicle occupants will increasingly look to use their smartphones to gain access to their vehicles and customize this experience.

In addition, as the number of sensors, safety and infotainment systems in cars grows, so does the requirement to interconnect them to in-vehicle computers. Here, using cables, which add significant weight and volume to a vehicle, poses challenges for manufacturability, cost, and complexity.

Figure 1 Wireless connectivity in vehicles enhances user experience. Source: onsemi

Bluetooth LE is a low-power and cost-effective alternative to traditional interconnectivity solutions based on controller area networks (CAN) and local interconnect networks (LIN). So, several automotive OEMs are trying to leverage a Bluetooth LE infrastructure to replace these technologies in some use cases.

Bluetooth LE has several advantages over other wireless technologies, which makes it the preferred choice for automotive applications, including:

Proven communication with smartphones allays concerns about interoperability
Standardized specification and certification
Robust performance in electrically noisy and harsh environments
Availability of AEC-Q100 automotive qualified parts
Low-power consumption which is a critical requirement in electric vehicles
Availability of low-cost system-on-chip (SoC) components and antennas

Bluetooth LE automotive use cases

Bluetooth technology in automobiles was first used with vehicle access systems, enabling features like the phone-as-a-key feature for passive-entry and passive-start. Future developments around Bluetooth LE in this application will see customized user experiences based on individual digital keys and profiles. For example, a vehicle will be able to automatically identify a profile stored in a driver’s or passenger’s mobile phone and then seamlessly adjust the position of mirrors, seats, and the steering wheel to match individual preferences.

Additionally, it will be possible to create shared keys for other vehicle users, eventually making phone-as-a-key a practical solution for the emerging trend of shared autonomous vehicles. However, this will also require profiles to be protected by the highest security levels to prevent them from being copied by unauthorized third parties who could steal or alter how the vehicle operates.

Here, it’s worth mentioning that low power is crucial in infotainment systems like telematics boxes and head-unit displays. Often, these systems include high-power-consumption connectivity devices like cellular telecommunications modems, Wi-Fi, and other connectivity protocols. These systems have stringent power budgets that must be adhered to so as not to place a drain on a vehicle’s battery when a car is not in use.

Meeting these requirements is driving system developers to look for low-power wireless MCUs that can shut off the higher power consumption components in the vehicle but still wake them up when needed. Bluetooth LE is an excellent option for this purpose, allowing a telematics box or head-unit display to determine if it needs to wake up to handle over-the-air software updates or perform other diagnostic functions, for example.

Apart from vehicle body applications, another emerging trend is to use radios featuring Bluetooth technology in battery-management systems to send periodic temperature and voltage information about battery packs to the main computer. Bluetooth LE can also help OEMs to reduce costs with features like wireless tire pressure monitoring systems (TPMS) that allow drivers to check tire pressure using their phones or even receive notifications when a tire is flat.

Bluetooth LE can also simplify designs for controlling multi-position power seats, mirrors, locks, and sunroofs. Apart from ultra-low-power consumption, a small form factor and the ability to secure data communication within and outside the vehicle are critical requirements when selecting a Bluetooth LE-enabled MCU for use in a car.

Low-power wireless MCUs

Besides connectivity, wireless MCUs also feature embedded security and ultra-low power for automotive applications. The wireless MCU shown below has four low-power modes to reduce power consumption while maintaining system responsiveness. These include sleep, standby, smart sense, and idle. Smart sense mode takes advantage of the low-power capability of sleep mode while allowing some digital and analog peripherals to remain active with minimal processor intervention.

Figure 2 The NCV-RSL15 wireless MCU is designed with a smart sense power mode. Source: onsemi

These features allow wireless MCUs to support applications like vehicle access, tire pressure, and tire monitoring systems for up to 10 years off the power from a single coin cell. Next, OEMs continue to find ways to exploit Bluetooth LE-enabled MCUs in developing lighter, more scalable battery management systems that are easier to manufacture.

Moreover, the wireless MCU shown above is built around an Arm Cortex−M33 processor core with TrustZone Armv8−M security extensions, which form the basis of its security platform. The MCU also incorporates embedded security with an Arm CryptoCell featuring hardware-based root-of-trust secure boot, many user-accessible hardware-accelerated cryptographic algorithms, and firmware-over-the-air (FOTA) capabilities to support future firmware updates and deployment of security patches.

Such security features make Bluetooth LE-enabled MCUs highly suitable for remote access devices.

Ben Widsten is product manager for Bluetooth Low Energy solutions at onsemi.

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Secure Bluetooth LE adoption on rise in automotive applications

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