The evolution of automotive computing and the rise of companion microcontrollers.
The automotive E/E architecture is undergoing a significant transformation, driven by the vision of a software-defined vehicle (SDV). This shift is leading to a change from traditional distributed and domain-based architectures to more centralized and mixed domain-zone architectures. Central Electronic Control Units (ECUs) are now powered by sophisticated system-on-chips (SoCs) that combine complex and interoperable functions, such as Advanced Driver Assistance Systems (ADAS), infotainment, and motion control. While these SoCs offer high performance, they can still face challenges in terms of performance, safety, and security when performing real-time operations.
This blog explores how automotive-specific, low-power companion microcontrollers (MCUs) cost-effectively address these challenges by managing real-time control, safety mechanisms, and other crucial vehicle functions.
As automotive design teams strive for faster development and greater efficiency, they’re adopting mixed domain-zone architectures and centralized cockpit compute systems. This shift has led to the use of powerful SoCs that act as the brain of the system, incorporating CPUs, GPUs, and DSPs to support advanced features like high-resolution displays, ADAS, and AI/ML capabilities.
However, these SoCs, often consumer-grade devices certified for automotive use, rely on full-featured operating systems that can compromise predictable and robust real-time performance. This trade-off between high-performance computing and reliable real-time operation is a key challenge in modern automotive systems.
As automotive architectures shift towards centralized compute, the companion microcontroller has emerged as a critical component, operating alongside the SoC. This automotive-specific microcontroller, also known as a Vehicle Interconnect Processor (VIP) or Digital Control Unit (DCU), performs low-level tasks that the SoC cannot easily manage. By running a Real Time Operating System (RTOS), the companion microcontroller ensures predictable behavior, improved real-time performance, and enhanced functional safety and cybersecurity. It also manages SoC startup and shutdown, acts as a communication gateway to the in-vehicle network, and provides a cost-effective path to systemwide ASIL B to ASIL D certification, meeting stringent automotive quality and safety standards.
To meet ISO 26262 compliance, it’s essential to isolate safety and application concerns. However, application processors (SoCs) are often not developed with safety in mind, focusing instead on performance. This lack of built-in safety mechanisms and limited safety documentation makes it challenging to predict behavior during failures. In contrast, companion microcontrollers are designed with safety in mind, supporting ASIL B to ASIL D and featuring built-in safety mechanisms for predictable behavior in failure conditions. While some designers consider using an SoC without a companion MCU, this approach requires a “safety island” within the SoC, which increases complexity, cost, and tradeoffs, limiting its practicality.
Fig. 1: Comparing safety, maturity, scalability, and price for four specific cockpit architectures and companion MCU implementations.
When using a companion microcontroller, there are several implementation methods to choose from, each with its own advantages and limitations. These include pairing a primary SoC with a smaller secondary SoC (A1), using a single SoC with a hypervisor (A2), integrating an ASIL B certified “safety island” within the SoC (A3), or combining a single SoC with a graphic MCU (A4). Regardless of the chosen configuration, it’s essential to separate real-time and Operation System (OS) functions. By using a companion MCU alongside the application processor, developers can reduce development time and effort and have a wider range of component options to consider.
A companion microcontroller plays a crucial role in Zone Controllers or the High-Performance Computer (HPC), performing various functions that can be grouped into system management tasks, application processor security enhancement, vehicle interface functions, and specialized functions. System management tasks include power management, temperature monitoring, and redundancy checks to ensure the SoC operates within safe limits. The companion MCU also enhances security by implementing Hardware Security Modules (HSMs) to meet automotive standards, such as EVITA and ISO 21434. Additionally, it functions as a communication gateway for in-vehicle networks, isolating network traffic from the SoC application processor and ensuring a more consistent and dependable user experience. Finally, the companion MCU can perform specialized functions, such as stepper motor control, sound capabilities, and video processing, improving system cost-effectiveness.
As companion microcontrollers become essential in automotive systems, designers are exploring additional integrated functions to enhance their capabilities. One emerging use case is the Video Safety Companion (VSC) for automotive instrument clusters, which processes graphics, manages IPC, system supervision, network functions, and security, while monitoring for correct graphics and rendering overlays in case of errors. Another area of growth is in supporting the increasing complexity of ADAS endpoints, where companion microcontrollers are required to meet the real-time processing demands of sensor fusion configurations. As AI and ML continue to drive more sophisticated ADAS features, companion microcontrollers will provide a secure foundation for real-time control and system integrity, while evolving to address growing system complexity.
Automotive-specific companion microcontrollers are essential components in domain-based and centralized compute architectures, enabling the efficient and cost-effective implementation of advanced AI-driven ADAS endpoints. By optimizing performance, safety, and security, companion microcontrollers allow SoCs to focus on application-related tasks, ensuring predictable behavior and maintaining system integrity.
With their robust HSMs, medium-agnostic vehicle network interfaces, and ability to handle lower-level tasks, companion microcontrollers provide a secure foundation for real-time control and system integrity.
As the industry advances towards more feature-rich, centralized architectures, new use cases will emerge, and Infineon’s TRAVEO and AURIX microcontroller families are well-positioned to support the growing demand for companion microcontrollers.
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