Computer Controls

Arm FuSa RTS available now

Since 1st July 2019 Functional Safety Run-Time System (Arm FuSa RTS) is available for customers.

Functional Safety Run-Time System (Arm FuSa RTS) is a set of qualified software components for Cortex-M microcontrollers, that lets developers focus on their end applications:

• Keil RTX5 real-time operating system (RTOS)
• A derivative of the Arm C library with the most commonly used C library functions
• Event Recorder for visibility to the dynamic operation of the software
• CMSIS-Core (the Arm specific part)

RTS is certified by TÜV SÜD to use in automotive, industrial, medical, and railway systems.

Arm Keil FuSa building blocks diagram

Together with the TÜV-certified Arm Compiler toolchain, software engineers can create and deliver a reliable, more secure and highly optimized end-user application, while getting the product to market faster.

RTS components

Keil RTX5

Keil RTX5 is a proven and well-established RTOS in the embedded space. Its predecessors have been around for more than 20 years. The latest implementation is the reference design for the CMSIS-RTOS API v2. It is easy to use and well supported within the µVision IDE/debugger. The debugger's features enable you to debug your RTX applications faster. As it is royalty-free, there are no run-time royalty payments or other hidden charges.

Ship your RTX based products without further fees or recurring costs. It offers flexible, low-latency scheduling, allowing you to use the best suited one in your application. It delivers fully deterministic behavior meaning that events and interrupts are handled within a predefined time (deadline).

Your application can rely on consistent and known process timings. It is written specifically for applications running on Arm Cortex-M based MCUs. It runs fast and requires only minimal MCU resources with a memory footprint as small as 5 KB (ROM).

Event Recorder

The Event Recorder offers an API (function calls) for event annotations to add it to the application code. These functions record events along with timestamps and additional information. The data is stored in the event buffer located in the RAM of the target hardware. The µVision debugger reads the content of the event buffer and displays it in multiple windows, depending on the data and its usage.


The Arm core-specific part of CMSIS-Core provides a hardware abstraction layer (HAL) for Cortex-M processor registers with standardized definitions for the SysTick, Nested Vectored Interrupt Controller (NVIC), System Control Block (SCB), MPU, and FPU registers, as well as core access functions.

Functional safety library

The Arm functional safety C library implements a restricted subset of functions specified in the ISO C99 C language standard and comes with usage guidelines and examples on how to work effectively with it. The following functions are included:

  • Math routines (acos, asin, log, etc.)
  • Buffer manipulation routines (memcpy, memset, etc.)
  • Character routines (isalnum, isalpha, toascii, etc.)
  • Data conversion functions (abs, labs, etc.)
  • String routines (strcat, strcpy, etc.)

Supported standards and cores


  • ISO 26262 (ASIL D)
  • IEC 61508 (SIL 3)
  • IEC 62304 (Class C)
  • EN 50128 (SIL 4)


  • Arm Cortex-M0/M0+
  • Cortex-M3
  • Cortex-M4
  • Cortex-M7

Arm FuSa RTS is certified in combination with the safety qualified Arm C/C++ compiler 6. This fully qualified software development environment lets you concentrate on the development and certification of the end application.

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