Green Hills Software, an ST Authorized Partner, has engineered an integrated hardware-software solution that offers significant advantages for embedded system developers.
This innovative platform merges the efficiency of Green Hills Software’s µ-velOSity™ Real-Time Operating System (RTOS) with the advanced capabilities of ST’s Stellar SR6 automotive Microcontroller (MCU) and its Microcontroller Abstraction Layer software.
The synergy between a reliable RTOS and a cutting-edge MCU is pivotal for modern embedded solutions. This article delves into the reasons that make this combination an optimal choice for developers, empowering them with a robust foundation for building real-world embedded applications.
The value of a collaboration between RTOS Vendor and SoC Manufacturer
To ensure seamless integration and optimized performance, a strong collaboration between an RTOS vendor and an SoC manufacturer is crucial.
System-on-Chip (SoC) manufacturers design customized solutions for sectors like automotive and industrial automation. The advanced features of their microcontrollers often surpass the capabilities of many real-time operating systems (RTOSes), which can present setup challenges and compatibility issues. ST and Green Hills started cooperating on the RTOS integration with various MCU families in 2013 when both companies decided to combine the benefits of their technologies and significantly improve the performance of the offered platform. This collaboration allowed µ-velOSity to benefit from access to the latest updates regarding hardware versions and documentation of the Stellar SR6 MCUs.
This foster added value for customers by accelerating feature innovation and stabilization. Customer satisfaction is heightened through the seamless integration of ST’s and Green Hills’ dedicated engineering resources, ensuring cohesive software and hardware development for the platform.
Developers can take advantage of the simplified shift-left testing with the Stellar architecture, which provides immediate access to a perfectly tuned production-focused RTOS. The MULTI® integrated development environment (IDE) offers fully integrated development tools with the Stellar Studio, which makes application development faster and debugging easier.
The Foundation of the Platform: The Stellar SR6 MCU
At the heart of this integrated solution lies the powerful and secure Stellar SR6 MCU, specifically designed for the demanding requirements of modern software-defined vehicles.
The emergence of software-defined vehicles has created the need for higher levels of performance, elevated safety, and more stringent security standards. ST has designed an MCU family for software-defined vehicles, which offers up to 10 times more computational power than the previous generation – The Stellar MCU family. It includes features that focus on the highest level of safety and security.
The Arm® Cortex-R52+ core serves as the foundation for a scalable and future-proof architecture, enhancing computational power. Complementing this are features like extensible memory with over-the-air update (OTA) capabilities, an ultra-real-time data routing accelerator, and built-in hardware virtualization that ensures freedom from interference. The integrated design, test and manufacturing approach of ST for automotive microcontrollers ensures architectural optimization, bringing best-in-class power consumption.
The Perfect Match: The µ-velOSity RTOS
What makes µ-velOSity the perfect match for the Stellar SR6 MCU? The μ-velOSity Real-Time Operating System features a unique architecture in which applications, middleware, and drivers run outside the kernel. With this configuration, μ-velOSity can provide memory protection using the Memory Protection Unit of ST’s Stellar SR6 MCU. The foundation for safe and secure applications is created by guaranteeing the isolation of the memory space. Once configured accordingly, each component remains unaffected by another’s failure (Freedom from Interference).
Green Hills and ST provide a great out-of-the-box experience by providing multiple different configurations: speed optimization, size optimization, and debug optimization, as well as a pre-certified sample BSP using ST’s MCAL software (according to ISO 26262 ASIL D). µ velOSity consists of roughly 2000 lines of C code and around 100 assembly instructions. The high maintainability and robustness of the Software help customers leverage the SR6’s longevity.
The µ-velOSity operating system comes with a priority-based, preemptive scheduler that makes it simpler for customers to utilize the Stellar SR6’s performance capabilities without compromising safety and security. For instance, the scheduler prevents priority inversion and guarantees that the most critical tasks are executed first.
Safety BSP – Bridging the Gap between Hardware and Software
The µ-velOSity Board Support Package (BSP) serves as a bridge between the application software and the physical hardware, functioning as a layer that abstracts the hardware details. For safety-critical systems, this BSP is carefully crafted to comply with safety regulations, such as ISO 26262 ASIL D, which includes measures for preventing faults, akin to the requirements for the Real-Time Operating System (RTOS).
A BSP is typically designed for a certain hardware and a certain use case, so, unlike the RTOS, it cannot be certified out of context. This means a BSP comes with an in-context certificate and safety manual. The BSP must address fault control, in that its drivers need to have appropriate measures to mitigate systematic and random hardware and software errors. To mitigate risks, the BSP should also make good use of hardware features, such as those provided by the Stellar SR6.
A key area of innovation of the Stellar SR6 revolves around functional safety and is based on four main pillars:
- Firstly, the MCU’s ASIL D framework, which includes the Cortex-R52+ CPU cores, the interconnect, and the memories, is engineered to meet the rigorous functional safety requirements of ASIL D to a high standard.
- A second safety pillar is hardware virtualization support to enable Virtual Machines (VM) to be assigned fault reactions and recovery), together with dedicated safety pins that can be assigned depending on the type of fault.
- A third dimension of the Stellar SR6 MCU’s safety innovation is replicating communication peripherals to enable the SW to implement measures for ASIL D.
- Lastly, ensuring the highest level of temporal accuracy is a core principle of the system. This is achieved through the implementation of an ASIL D system time base. This highly reliable timekeeping mechanism actively detects and rectifies any timing discrepancies to maintain safety compliance.
What this Symbiosis Looks like in Real-World Applications
ST, Green Hills, and Cetitec join forces to demonstrate the power of their combined technologies in real-world software-defined vehicles. The demo consists of two software components: the Cetitec Gateway and the VConverter.
The automotive industry is currently witnessing a paradigm shift towards software-defined networking (SDN) within vehicles. This transition is driven by the goal of establishing a high-speed, deterministic, and robust communication backbone. Such a backbone is essential for supporting the increasing array of vehicle functionalities, all while maintaining low latency and without the need to overhaul the existing network infrastructure. Until we get to that point, we need to bridge the gap between automotive-specific protocols such as CAN, LIN, FlexRay, and I/O manipulation and the service-oriented world, where much of the communication is going through Ethernet technologies.
Cetitec Gateway is highly configurable, rich in functionality, and supports all the standard automotive networking protocols. With many development and maintenance hours behind it, the Cetitec Gateway has been tested in the field and can effortlessly perform the job. It supports post-build configuration, which allows configuration to be modified through a binary file that can be changed at runtime. On top of the automotive standard protocols, it supports the so-called application bus that can be easily adjusted to the concrete application.
In this example, it is adapted to another Cetitec component called VConverter. VConverter is a component that connects automotive-specific communication protocols with the Green Hills ecosystem of applications.
On the ARM® Cortex-R52 core running µ-velOSity, the system can effectively manage connections between automotive communication protocols and Green Hills applications, determining whether processing should occur internally or be exposed externally.
The VConverter performs two functions:
- The first one exposes selected attributes to a client on another core or in an entirely different node on the network. In this case, the protocol is independent of the actual transport layer.
- The second function enables one core to exchange information with the other through a simple configuration. The Data Management Engine (DME) core running the Cetitec Gateway will provide information to the core running Green Hills µ-velOSity. Here, the VConverter will expose the needed information to the outside clients. The Cetitec Gateway will run on the DME core (cortex-M4 of the SR6), which will perform the functionality and offload the main core (cortex-R52) running Green Hills µ-velOSity.
The DME core can be used for particular functions or routing applications, offloading the main core for application development. The VConverter enables communication between the cores. This component operates on the R52 core running µ-velOSity and the DME core, allowing the CEITEC Gateway to communicate effectively with the applications running on µ-velOSity. It abstracts the DME’s functionality, so applications running within µ-velOSity remain unaware that they are exchanging information with the DME.
This solution is an excellent fit. It leverages the Stellar SR6’s multi-core architecture and µ-velOSity’s performance along with Cetitec’s Networking Solutions, allowing for a successful transition to a software-defined vehicle with highly configurable and efficient networking.
