The pre-certified Flexible Safety RTOS

Real-Time Operating System (RTOS)

A real-time operating system (RTOS) provides services, which helps to manage the continuously rising complexity of software development in embedded systems. In comparison to an operating system (OS) like Linux or Windows, the RTOS provides:

Deterministic and highspeed event handling

A scheduler which is able to meet timing deadlines

Usable from tiny microcontrollers to big processors

Note: When discussing the fundamental properties of a real-time operating system, it is not about super fast timings (of course, they are super fast) - more important is the guarantee and determinism of achieving the timing deadlines.

The following video gives an overview of the Flexible Safety RTOS.

Introduction to Flexible Safety RTOS

Your benefits, provided by the Flexible Safety RTOS

RTOS Safety Capability

The Flexible Safety RTOS is pre-certified for all standards, which allows a pre-certification. We achieve in all certifications the highest safety capability a pre-certified software can achieve.

Automotive: ISO 26262 - ASIL D

Industrial: IEC 61508 - SIL 3

Medical: IEC 62304 - Class C

Railway: EN 50128 - SIL 4

Note: The safety capability, according to the basic standard IEC 61508 - SIL3, covers many other standards as well. For example Nuclear Sector (IEC 61513), Machinery Guidance (ISO 13849), Process Industry (IEC 61511) or Machinery (IEC 62061)

Compiler Independence

The certification is performed in a way, that no certified Compiler is required. We can perform certification of the Flexible Safety RTOS with all ANSI-C compiler. Popular compilers are:

IAR Embedded Workbench

Tasking Compiler

Keil Microcontroller Development Kit (MDK)

HighTec Development Platform

Safety with Certificate

Independent assessors have been checked the development multiple times and confirm the safety capability of Flexible Safety RTOS with a certificate. All you need for your safety system development:

Certificate with a RTOS Version List

Safety Manual

User and Integration Manuals

Flexible Certification

The development and certification process is designed to achieve the highest possible flexibility for all end-users of the Flexible Safety RTOS:

Free device selection for a certified CPU core

Change compiler switches or use compiler updates

RTOS is independent of the hardware manufacturers

Supported Services

Multi-Tasking Scheduler

The core service, called scheduler, is selecting and changing the currently running task

Priority based preemptive multi-tasking policy

Optional cooperative multi-tasking policy

Constant runtime on any number of tasks

Software Timer

The software timer service provides the ability to execute callback functions at a specific time

Cyclic callback function execution

One shot timer callback function

System tick or hardware timer as time base

Space Protection

The space protection module is managing the MPU or MMU of the hardware core

Group one or more tasks with same permissions

Separate RTOS memory space from application

Optional activate tasks executing in privileged mode

Memory Management

The memory management is based on equal sized memory block arrays, called partitions

Any number of memory partitions allowed

Support multiple block sizes for different partitions

Constant runtime for fetching and releasing blocks

Event Flags

The event flags is a service which allows synchronization based on multiple conditions

Up to 32 flags in a single flag group

Supports operation if any masked flag is set

Supports operation if all masked flags are set

Semaphores

The semaphore service combines the classic features of counting and binary semaphores

Provides counting semaphores

Supports binary semaphores

Mutex

The mutex service is designed to avoid priority inversion during accessing shared resources

Supports the priority inheritance protocol

Queue

The queue is a data queueing service to pass a series of data between tasks

Supports queueing mode: first-in-first-out (FIFO)

Supports stacking mode: last-in-first-out (LIFO)

Communication with zero copy technology

Mailbox

The mailbox service is an event signaling service, which offers the transport of a single event data set

Event data is consumed autonomously

Communication with zero copy technology

Shared Memory

Shared memory adds a defined memory area to one or more tasks with enabled write permissions

Grants memory access to one or more tasks

Hardware Monitoring

This module provides monitoring of some hardware components

Task and hardware stack monitoring

Memory protection register monitoring

Space protection configuration monitoring

Hook Function

The kernel provides several hook function interfaces to adjust or extend the system

Task lifecycle hooks (create & delete)

Timing hooks (system tick & idle time)

System hooks (context switch & task return)

Pre-certified Safety RTOS

Safety Capability

When using a real-time operating system in a safety system, we need to ensure the correct function. The way and depth for proving of the functional behavior depend on the target market of the safety system. Each primary market has definitions and rules for the way to prove the correct behavior, written in standards:

Industrial: IEC 61508

Medical: IEC 62304

Automotive: ISO 26262

Railway: EN 50128

Aerospace: DO-178C

We call the activities, required to pass the independent safety assessment for a specific standard: the certification. When performing these activities out of the context of a real safety system, we call the resulting component: a pre-certified component.

For the required depth for proving the functional behavior, the standards define safety capability levels with different names. The levels are derived from the occurrence probability of potential risks and the severity when happening:

Safety Capability Overview

Unfortunately, there is no simple mapping of safety capabilities from one market to another. The figure above shows a rough overview, based on the failure rate per hour. Some additional factors are important to consider (e.g., controllability, definitions of severity or risk acceptability frontier)