When developing motor control for automotive and industrial systems, functional safety is a core requirement to ensure a motor does not produce unintended torque or speed.
However, implementing complex algorithms like Field-Oriented Control (FOC) as a functionally safe component introduces severe architectural complexity, significantly increases development effort, and degrades overall performance.
To solve this, NXP utilizes a safety decomposition approach that divides the application into a non-safety-related part (QM) and a safety-related part (ASIL). For this approach, NXP plans to provide the Automotive Safety Checker Library (ASCLib), which delivers ready-to-use safety checkers for the safety part. This enables high safety compliance without requiring a redesign of the QM motor control (MC) part.
The Perfect Match: AMMCLib (QM) + ASCLib (ASIL)
Many applications use highly optimized NXP's Automotive Math and Motor Control Library (AMMCLib) for the motor control part. While AMMCLib delivers exceptional performance, it is a Quality Management (QM) level library.
Compliance with safety standards (such as ISO 26262) required teams to build custom safety mechanisms around the QM-level AMMCLib, consuming significant time and effort. NXP's ASCLib solves this by providing standardized, production-ready safety checkers. This eliminates proprietary safety software development and significantly reduces time-to-certification.
How AMMCLib and ASCLib Fit Together
The block diagram below illustrates a standard FOC system using this concept. The blue motor control blocks represents the QM-level AMMCLib functions, while the green blocks represent the ASCLib checkers that monitor key points to ensure safety. This architecture is based on the IEEE Low Complexity Safety Concept for FOC PMSM.
This reference architecture shows that integrating ASCLib requires no changes to the existing QM motor control architecture. Full data-type compatibility allows ASCLib checkers to map directly to AMMCLib signals, ensuring seamless interconnection. The architecture assumes that Freedom from Interference (FFI) between the safety-related and QM software components is ensured.
While standard FOC is a common use case, ASCLib is not limited to it. Thanks to its modular, independent blocks, the library supports alternative topologies and advanced techniques - including sensorless FOC and single-shunt current measurement.
Inside ASCLib: A Layered Safety Architecture
The ASCLib features a highly structured, layered software model organized hierarchically into Layers and Packages:
The Service Layer (Top Layer)
Exposes high-level functionalities directly to the safety application through two independent packages:
- High-Level Checkers (HLC): Wide range of application-level safety checkers tailored for various motor control systems.
- Fault Manager (FMG): Sophisticated fault-handling component managing error synchronization, configuration, and application notifications.
The Core Layer (Foundational Layer)
Provides the low-level building blocks utilized by the Service Layer. It consists of two essential packages:
- Low-Level Checkers (LLC): Delivers fundamental mathematical and verification functions.
- Fault-Debouncing (FDB): Provides generic fault debouncing algorithms.
 Developer Tip: The entire library is fully modular, isolated, and independent. If your application requires a unique checker, you can easily build your own custom checkers using the existing low-level blocks inside the LLC and FDB packages. Furthermore, the Fault Management (FMG) package is entirely optional—you are not forced to use it and can implement your own application-level error handling instead. |
Not Just For Automotive
Don't let the name fool you. While ASCLib has "Automotive" in its title and natively supports ISO 26262 workflows, its safety principles are universal. ASCLib applies perfectly to industrial systems complying with IEC 61508.
To fit seamlessly into your existing development workflow, ASCLib features a dual-delivery option:
- Pure C Source Files: For direct integration into any bare-metal or RTOS-based embedded project.
- BAM (Bit Accurate Models): Ready-to-use blocks for Model-Based Design (MBD), allowing you to drag, drop, and simulate your safety architecture directly in MATLAB®/Simulink®.
Key Benefits for Developers
- AMMCLib Remains QM: Keep using your existing, highly optimized AMMCLib code for core motor control.
- Model-Based development: Accelerate your design cycle by building and simulating your entire safety part using dedicated ASCLib BAM directly in MATLAB®/Simulink® before generating target C code.
- Accelerated Certification: Pre-designed safety checkers and integrated fault management significantly simplify your safety compliance and auditing processes.
Get Started and Share Your Thoughts
ASCLib is designed to be completely MCU-independent, giving you the flexibility to deploy it across various NXP hardware platforms. To accelerate your development, it is planned to be fully verified and ready to integrate with NXP’s automotive and industrial MCUs. By separating control from safety, you get the best of both worlds: maximum motor performance and uncompromising safety.
Working on an upcoming ISO 26262 or IEC 61508 motor control project? Let’s discuss in the comments how the AMMCLib + ASCLib approach can simplify your design. We would also highly appreciate it if you could take a moment to fill out our quick survey below to share your insights with us!