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Oct 08, 2025 / 4 min read
Virtual ECUs (vECUs) have significantly changed software development and testing within the automotive industry. By simulating the functionality of physical ECUs in a virtual environment, vECUs facilitate quicker software development and validation, and significantly reduce the need for physical hardware. This allows software teams to initiate development and testing even in the beginning when no actual hardware is available. More importantly, enabling Software-Defined Vehicle (SDV) processes, such as Continuous Integration and Continuous Deployment (CI/CD), utilize vECUs throughout the entire software lifecycle, and enable the fastest feedback on code changes and bug-fixes.
Therefore, it is crucial for leading Software-in-the-Loop (SIL) tools like Synopsys SilverTM to address the latest industry requirements by supporting the virtualization of open-source operating systems such as FreeRTOS. This enables customers to use Silver in known comprehensive workflows to build vECUs. It was never simpler to generate FreeRTOS-based vECUs for deterministic and reproducible SIL test execution.
For decades, the world of automotive software has been dominated by AUTOSAR Classic – a reliable but heavyweight standard. Recently, however, OEMs and suppliers are increasingly investigating lightweight alternatives like FreeRTOS. What once sounded like a tool for microcontrollers or IoT now gains traction in vehicle architectures.
In the age of SDV, OEMs do no longer depend solely on AUTOSAR Classic for real-time specific ECUs. Even though FreeRTOS is not an equivalent replacement for AUTOSAR Classic, it brings significant value to the developers of embedded devices. FreeRTOS serves as a lightweight, open real-time operating system (RTOS) that is particularly well-suited for applications demanding little resources. It operates under the FreeRTOS License, which is a permissive license similar to MIT, and is available for all major architectures (Arm, RISC-V, MIPS, Intel) that allows high flexibility in sourcing the right MCU and semiconductor vendor. For example, Infineon also provides FreeRTOS support as part of their MCU Starter Kits1.
What OEMs Gain from Using FreeRTOS:
On the other hand, FreeRTOS does not provide an automotive-grade middleware stack and associated tooling out of the box. Essential middleware functions like communication, diagnostic, or system state management are missing and force the OEM developers to find individual solutions. Thus, it is not a surprise that today’s OEMs experiment with hybrid solutions based on FreeRTOS & AUTOSAR Classic modules.
In fact, it comes with its own set of challenges:
Without proper versioning and update management, technical debt builds up quickly.
While AUTOSAR is still the dominant solution for safety-critical ECUs, with SAFERTOS2 we’re seeing a solution also to use FreeRTOS in safety critical systems. Additionally, we’re seeing a clear market transformation for:
These concepts demand modular, scalable software – and for many domains, AUTOSAR Classic is too rigid and resource-heavy. FreeRTOS is filling the gap and is gaining share.
Ever since, Synopsys Silver has given priority to provide a software stack- and framework-agnostic simulation solution. Today, this enables our customers to benefit from the same maturity level of simulation capabilities and expertise to explore and adapt new approaches like FreeRTOS/SAFERTOS for automotive software development. Silver provides a comprehensive, automotive-grade development environment – also applicable for RTOS-based ECUs – featuring:
vECU creation and integration into a vast co-simulation and 3rd party tool ecosystem to enable closed-loop, multi-node validation and verification based on automotive standards
Reproducible simulation results by deterministic task scheduling decoupled from the host system’s time.
Single- and multi-core support for realistic simulation behavior
Intuitive hands-on stimulation, measurement and debugging during simulation runtime
Interactive UI and headless simulation execution
Windows and Linux support
etc.
The listed features by far exceed the capabilities of other RTOS simulators, which clearly lack the requirements of automotive software development and testing teams and their supply chain.
The solution lends itself to shift left not only start of production (SOP) dates, but also technological assessments and decision making as described above. For instance, porting resource intensive AUTOSAR Classic software components to a lightweight RTOS-based stack running on a separate core.
The associated video in this blog showcases how to debug a Silver vECU that runs an Onboard Charging software component on top of FreeRTOS in addition to a MICROSAR-based Battery Management System distributed on two cores.
In summary, the advanced feature set outlined here positions this vECU solution as a transformative tool for automotive software development and validation. Its integration capability, deterministic simulation, multi-core realism, and flexible runtime options empower engineering teams to accelerate production timelines and make informed technological decisions early in the process. By supporting industry standards and offering compatibility across platforms, it surpasses conventional RTOS simulators and stands as an essential asset for modern automotive software projects.
References
AURIXTM TC3x from Infineon supports FreeRTOS
https://www.infineon.com/market-news/2024/infatv202411-027
SAFERTOS® is a pre-certified safety Real Time Operating System (RTOS) for embedded processors
SAFERTOS®, the safety certified RTOS - available pre-certified to IEC 61508