Real-Time Systems

Presented by:

www.scisys.co.uk

Stuart D Fowell

SciSys AMS Prototyping

CCSDS Spring 2008 Meeting, Washington D.C, USA

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Overview Project Overview & Reference Mission

Constraints & Assumptions

Use Cases

Tailoring of Specification & Feedback

Design & Implementation

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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SOIS Reference Implementation SciSys (UK) and Astrium SAS (FR) Customer: ESA Jan – Oct 2008

Objectives: Prototype SOIS architecture over SpaceWire and MIL-

STD-1553B Inc. implement tailored AMS in SOIS, driven by onboard use cases

Investigate SOIS Plug-and-Play architecture on SpaceWire

Deploy on ESA’s RASTA Test Facility for future use Provide feedback on SOIS Red Books Provide draft Device Enumeration and Virtualisation Red

Books

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Reference Mission

Data Storage InstrumentStar Tracker

Platform OBC Payload OBC

SpWRouter

MIL-STD-1553B

SpaceWire Link

SpaceWire Link

SpaceWire Link

SpaceWire Link

Control Momentum

Gyro

TM/TC Module

SpaceWire Link

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Constraints & Assumptions Only focussed on onboard software

architecture Hence, no RAMS Gateway

Use SOIS Subnetwork Packet Service as AMS transport layer & offer available QoS’s to users

Allow for integration into wider system FDIR strategy of active/redundant system nodes Simplifies Configuration Manager and Registrars But not a focus for this project

Modular design so only required functions are linked in

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Use Cases Send Message from Onboard Application to Onboard

Application E.g. a Mission Timeline application sends a telecommand

to a Payload Controller Query from Onboard Application to Onboard Application

E.g. an FDIR application queries the status of a Payload Controller application

Announce from Onboard Application to other Onboard Applications

E.g. an FDIR application notifies a group of Payload Controller applications to shutdown

Publish Message from Onboard Application to Subscribed Onboard Applications

E.g. a Payload Controller application publishes the latest data to interested applications, e.g. a Mission Autonomy Controller application

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Tailoring of Specification & Feedback

See SciSys TNs: DOC 006 AMS Terminology Understanding v1.0a DOC 007 AMS Draft Standard Feedback v1.0a DOC 008 AMS Implementation Assumptions v1.0a

SciSys AMS Prototyping - CCSDS Spring 200811th March 2008

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Design & Implementation Modular Design using UML 2 Implemented using MISRA subset of ANSI C RTEMS operating system LEON2 SPARC-based processor SpaceWire Network and MIL-STD-1553B bus Best Effort, Assured and Reserved SOIS QoS

Prototype on Linux PC with UDP simulation of SpaceWire

Port to ESA’s RASTA Test Facility