CERTON’s Safety-Critical, Certified-Off-The-Shelf (COTS) Software

CERTOS™

 

CERTOS™ is a partitionable, Real Time Operating System (RTOS) that supports both POSIX and ARINC 653 standards. Hard real time operating systems allow task and application layer portioning in a manner that supports safety critical applications. Any single task or application that hangs, corrupts memory, or generally causes a fault will not cause complete system failure. The faulted task or application can be independently halted, reset, and re-started. In order to create a partitionable software layer the underlying hardware must contain a Memory Management Unit (MMU). Most modern, advanced microcontrollers contain an onboard MMU.

 

CERTOS™ in a non-partitionable environment provides a Hard Real Time Operating System (RTOS) that is POSIX-compliant, supports multiple threads execution without the memory protection and portioning that is available in systems with an MMU. In non—MMU environments, all memory is shared (flat), between threads, so partitioning for separate criticalities and application security levels are not possible.

 

CERTOS™ includes both ANSI C and POSIX standard libraries such as math, stdio, string, etc. These libraries provide functionality such as sin(), cos(), fopen(), etc.

 

 

CERTOS™ FAQs

 

Question

 

What´s the difference between Hard Real Time and Soft Real Time?

 

Answer

 

As any Windows user knows, a single tasks that consumes 99% of the CPU will prevent other tasks from executing (i.e. the MP3 player locking up Microsoft Word) . This is due to the fact that Windows is not a Hard RTOS, but operates on a software based time slice, Round-Robin (Soft RTOS) scheduling algorithm. Hard Real Time Operating Systems are Interrupt Driven from an external source, and require all tasks to complete within the time allowed. Any task that fails to complete will not cause any other thread to execute (blocking) at the next scheduled time. Soft Real Time Operating Systems are at the mercy of other threads not causing a blocking or resource hogging scenario.

 

Question

 

Why do I need an MMU to support multitask and multi application partitioning?

 

Answer

 

Without an MMU there is no protection from one tasks or application from "seeing" another task or application´s memory space. This means that any task or application could inadvertently write over or read another application memory, thus altering data and program flow.

 

Question

 

What BSPs are currently available for CERTOS™?

 

Answer

 

Currently the CERTBOARD™ is the only Hardware platform for which a DO-178B cert kit is available. DO-178B certkits as well as software kits for other Hardware platforms can be developed. For Information contact Certon.