STMicro’s Automotive MCU Enables Secure Remote Updates

The SPC58 Chorus H Line offers a triple-core solution (200 MHz) and is pin-to-pin compatible with ST’s SPC58 4B and SPC58 C lines of MCUs.

By Murray Slovick, Contributing Editor

Critical vehicle powertrain, body, chassis, and infotainment features are increasingly defined by software securely delivering data, software, and firmware updates such as fixes and new functions. As a result, over the air (OTA) is now considered an essential method of updating and enhancing future autonomous vehicle performance.

To date, in the universe of non-self-driving cars, OTA capabilities have been an unqualified success. Tesla has been doing it for years and the concept is pretty simple: Software updates are sent remotely; there’s no need to take your Tesla into a dealership and have them physically connect to your car to provide the latest versions of software and firmware. This allows Tesla to easily add new features that weren’t available when the car was purchased.

SPC58 H Chorus MCUs

With that in mind, STMicroelectronics has launched a new flagship for its SPC58 H line of Chorus automotive MCUs, designed to allow OTA updates of connected-car functionalities and do so in a secure manner.

The SPC58 Chorus H Line offers a triple-core solution (200 MHz) introducing new features to support connected gateway applications with Gigabit Ethernet MAC for fast downloads, a hyperbus interface to extend the internal RAM and an eMMC interface for storing large data files.

The SPC58 H is a general-purpose MCU targeting body, networking, and security applications. (Source: STMicroelectronics)

It’s designed for body, networking, and security applications such as gateways, body-control modules, battery management, and ADAS safety systems. Inside the SPC58 Chorus H Line you’ll find communication interfaces including two Ethernet, 16 ISO CAN FD, and 24 adhering to the LIN protocol.

“The way carmakers create, configure, deploy, and maintain new vehicles is changing, as software-defined functionality makes advanced features, flexibility, and convenience ever more widely accessible,” says Luca Rodeschini, Automotive and Discrete Product Group Strategy and Microcontroller Business Unit Director, STMicroelectronics. “Our latest and highest-performing Chorus microcontroller, being OTA-ready and with dual Ethernet ports up to gigabit speeds, creates a state-of-the-art platform for seamless, safe, and secure in-car connectivity and control.”

The SPC58 Chorus H Line provides a seamless extension with compatible devices having from 2 up to 10 MB of flash memory. Moreover, it’s pin-to-pin compatible with the other Chorus MCUs: the SPC58 4B and SPC58 C lines.

The part also can act as a gateway for multiple electronic control units (ECUs) transferring data across the many different networks found in vehicles via two Ethernet interfaces also on-chip. Gateway controllers play a fundamental role as a communication bridge between the various ECU networks used by different applications. They manage the exchange of data with external interfaces including CAN (low, high speed), LIN, ISO-9141, FlexRay, and Ethernet protocols. Two independent Ethernet ports provide connectivity between multiple Chorus chips throughout the vehicle to facilitate in-vehicle diagnostics.

Protective Measures 

Updates need resilience to cyber attacks, so security is of paramount importance. To protect connected-car functions and allow OTA updates to be safely applied, the new Chorus chip uses on-chip code storage and a hardware security module (HSM) capable of asymmetric cryptography.

Said by ST to be designed in compliance with ISO 26262 specifications, the SPC58 H Line meets safety standards up to ASIL-D as well as the EVITA Full security level with support for asymmetric keys. Being EVITA Full compliant means it implements industry-leading attack prevention, detection, and containment techniques.

The EVITA project was established to create automotive architectures to protect security-relevant components and sensitive data. The consortium established three HSM security levels (Light, Medium, and Full), with several features similar to the Secure Hardware Extension (SHE) and Trusted Platform Module (TPM) specifications.

The new top-of-the-line Chorus microcontroller gets more than triple-core architecture clocking at 200 MHz. It has 10 MB of on-chip flash and more than 1.2 MB of RAM, and delivers a CoreMark score of 1763. CoreMark is a synthetic benchmark that measures the performance of central processing units (CPUs) used in embedded systems. The speed comes by way of ST’s Power z4 core Architecture.

The SPC58NH92x further allows current application code to run continuously even while an update is downloaded and made ready to be applied later at a safe time. The older software can be retained, giving the option to roll back to the previous version in an emergency. HyperBus and eMMC/SDIO high-speed interfaces to off-chip memory are also integrated, enabling further storage expansion if needed.

The SPC58 H Line, available in packages such as TQFP144, is fully scalable up to FPBGA386.

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