Use of EDS for S/W Bus Adaptor

CCSDS SOIS 2013 Spring Meeting

Jonathan Wilmot NASA GSFC

1

Exemplar CFS Architecture

Instrument 1

Manager

TimeServices

C&DH App

Inter-task Message Router (SW Bus)

EventServices

Stored CommandingScheduler

House keeping

ExecutiveServices

Instrument 2

Manager

Checksum

cFE App

CFS App

S-Comm

GN&C App

SoftwareBus

CndIngest

Telemetry Output

SBC1553

SpacecraftData

Recorder

SpaceWire

1553 BusController

S/CData

DataStorage

Health&

Safety

EDACMemoryScrubber

Time HW

RecorderManager

Power

Power hw

TimeManager

LimitChecker

FileManager

CFDP File Transfer

RAM & EEPROM

HousekeepingRecorder

ControlLaw

StateDetermination

OnboardModels

TableServices

IMU

Altimeter

GPS 232

422

GPS IO

Alt IO

LN200 IO

232

GNC Sensors

5 Hz

5 Hz

50 Hz

SpaceWire

CFS Software Bus (SB)

• CFS components publish/subscribe to CCSDS packets– Packets are either telecommand or telemetry– Publishers have no knowledge of subscribers

• One publisher to many subscribers is typical – Control log, Fault management, data storage, telemetry output

• Send and forget • Subscribers can request packet meta data (Publisher appid, system, subsystem)

– Subscriptions are based on packet app id (2^11)– Common CFS applications use a consistent set of app ids, but missions can

redefine them– C structures are used in the software to extract packet data

• CCSDS headers are not part of the C structures but via abstractions

• Ad-hoc tools are used to convert between C structures and ground systems and tool databases– Common definition parsed to generate packet definitions for other systems

• NASA working to establish CFS governance model and community– Architecture, software, and tools commonality across many NASA missions– Potential support for SOIS MTS compliance (Likely in the long term)

3

CFS Software Bus (SB)

• SB implements QOS only at the network interfaces– SB API accepts QOS parameters and passes them down

• There is a Software Bus Network (SBN) component that plugs in for each network type (Ethernet, TTEthernet,1553, SpaceWire...)– SBN is also used for interpartition (ARINC 653, PikeOS...), inter-core

messaging (Multi-core), and intra-processor– SB is not aware that SBN(s) exists– SBN will pass network to network through traffic– SBN implements a peer to peer network

• No protocol master, connection mappings are kept local• Peers can come and go at runtime• All subscription requests are replicated (This can have scaling issues)

• Ground interfaces are through Command Ingest and Telemetry Output plugins

• Not all components look at packet contents– Data storage, telemetry output, both just filter and forward 4

Formats

5

MSB LSBbit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

CRC SecH

Rsvd

Data

sizeVersion Type ID Operation CodeOrigin Code

System ID Content ID sizeContent ID

Seconds MSWSeconds LSW

Source SystemCounter

Source SubsystemMilliseconds Rsvd

CCSDS format

Data Exchange message (DEM) format

• CFS may move toward the DEM format which moves beyond the 2^11 appid (topic) limitation – Support for audio and video encapsulation

EDS gets used in many places

6Device422

DeviceI/O

& Driver

Device

SpaceWireI/ODevice

Device

RIU

1553I/O

Device

Device

I/OSchedule

Device specific driver(s)

Raw Sensor

processing

DataConsumers

Channelizations and service type (packet…)defined here

device

device

device

I/OSchedule

Subnetwork services EDS(s)

Software Bus

Network(SBN)

Software Bus

Network(SBN)

Partition, core, network…

7

Layered Approach:Use of EDS in the System Stack

D1

D2

D3

RIU 1

DVSDAS

Sub PS

DVSDASSub MAS

Software Bus

Adaptor

SpacecraftInterface

(Data Handling)

MissionControlSystem

RS422

SpW

1553

SpW

API

API

SW Bus TM/TC

D3 FI

SpW Access

D1 FI

SpW Access

D1+D2 FI

1553 Access

D1+D2+D3 FI

MTS Access

D1+D2+D3 FI

TM/TC Access

EDS describes interfaces of

Physical Devices

EDS describes interfaces of SW

Components

EDS describes interfaces of Spacecraft

EDS

EDS

EDS EDS

EDS

EDS describes interfaces of SOIS

implementation API

D1+D2 FI

SOISAccess

EDSTelemetry

Output

SensorProcessing

SpaceWire1553

Subnetwork I/O

HW and/or software

logic

End to End

CFDP FileTransfer

FileManage

r

MassStorage

Telemetry

CommandRTU driver

comm

Meta data for file contents?

HW

Star Tracker

HW

ReactionWheel

RTU

HWXTEDS

therm

istor

therm

istor

1451

EDSEDSEDS EDSEDS EDSEDS

EDSEDS

EDS

Telemetry

monitorsEDS

EDSEDS

EDS

comm

XTCEdatabase

1451

SOISStack

EDS

Software Bus SOIS MTS

Control Center