12006 MAPLD International ConferenceSpaceWire 101 Seminar NASA SpaceWire Architectures: Present &...

12006 MAPLD International Conference SpaceWire 101 Seminar

NASA SpaceWire Architectures:

Present & Future

Glenn Parker Rakow

NASA – Goddard Space Flight Center

2006 MAPLD International Conference

Washington, D.C.

September 25, 2006


•SpaceWire point-to-point links•16 links from segmented detector array & readout Electronics to Instrument CDH

•Science Data & Commands

•PCI

•Instrument CDH to Memory

•Memory to DSP

•MIL-STD-1553

•CMD bus to Spacecraft

Current SpaceWire Architectures: Swift Data Flow

Detectors &Instrument Readout Electronics

Mem

SpW

Processor

DSP

Cmd Bus CDH ACS

16

Instrument CDH Spacecraft

Back-plane

Detectors &Instrument Readout Electronics

Mem

SpW

Processor

DSP

Cmd Bus CDH ACS

16

Instrument CDH Spacecraft

Back-plane

1553


Current SpaceWire Architectures: LRO Data Flow

Processor Memory IOHighrate

Comm

Low rateComm

Instr AInstr C

Low Rate/Unique serial bus

Instr B

SpaceWireRouter

Parallel Bus

SpaceWireRouter

SpaceWire SpaceWire

SpaceWire SpaceWire

C&DH

PowerSupply

Backplane

HGAHi- Rate

Xpndr

Xmtr

Low- Rate

Parallel Bus

Processor Memory IOHighrate

Comm

Low rateComm

Instr AInstr C

Low Rate/Unique serial bus

Instr B

SpaceWireRouter

Parallel Bus

SpaceWireRouter

SpaceWireRouter

SpaceWire Router

SpaceWire SpaceWire Router

C&DH

PowerSupply

Backplane

HGAHi- Rate

Xpndr

Xmtr

Low- Rate

Parallel Bus

•Routed SpaceWire traffic

•End-node routers on C&DH boards

–Used as Serial backplane

»Single Board Computer Board

»Instrument Interface Board

»S-Band Communication Board

»Ka-Band Communications Board

•Interface to moderate rate instruments

•Not memory mapped like RMAP or GAP

•Side band signaling using Time-Codes

–1pps

–Barker code detect – uplink

–Upper level flow control on downlink frames

•MIL-STD-1553

•Interface to spacecraft subsystem

•Used for low-rate heritage instruments


SpW Port

SpW Port

SpW Port

Router

SpW

Port

SpW Port

SpW

Por

t

SpW Port

SpW Port

Instrument RouterRouter

SpW Port

LocalcPCI

Instrument Processing Electronics

Interface Board Focal Plane Array Processor(FPAP) # 1

(FPAP) # 2

(FPAP) # 3

Router

Router

SpW Port

Local Port

Local Port

Local Port

Local Port

Local Port

Local Port

SpW Port

Local Port

Local Port

Local Port

SpW Port

SpW Port

SpW Port

Router

Lo

cal P

ortS

pW P

ort

SpW Port

SpW

Po

rt

SpW Port

Compression&

Packetization

SpW Port

Note:

Colors denote logical address for aparticular destination address

Focal Plane Electronics(FPE) #1

Packet # 1

CMD Buffer

Pixel Data Segment # 1

.

.

.

.

.

.

.

Packet # 2

Packet #N

SpW Link


Pixel Data Segment # N

Packet # 1

CMD Buffer


.

.

.

.

.

.

.

Packet # 2

Packet #N

SpW Link


Pixel Data Segment # N

FPE # 2

FPE # 3

FPE # 4

FPE # 5

Recorder

SpW LinkMemory

Comm

Clk Data

Current SpaceWire Architectures: JWST Data Flow


Current SpaceWire Architectures

• JWST– Routed SpaceWire traffic

• From 4 instruments to local router to end node router (Instrument C&DH [IC&DH]) (cable)

• ICDH end node router to hardware processors (same box over backplane)

• Hardware processors to compression engine (same box over backplane)

• Compression engine to recorder (cable)

• GOES-R – Point-to-point links– Instrument - C&DH with Reliable Data Delivery Protocol


Traditional Systems

Red

Black

Black

BluePurple

Purple

Purple

Red – High-speed interfaceBlack – Discrete sync pulseBlue – TDMA low rate bus (MIL_STD-1553)Purple – Parallel Backplane

Legend:

• Different physical interfaces using different protocols that require unique hardware and software to bridge between them

• Serial interface at one point per enclosure @ NIC

• Extra board area and more power for multiple interfaces

• Only boards in same enclosure have memory mapped access via arbitration

• Enclosures represent limited access

• Reuse & reconfigurability limited


Non-BlockingCross-Bar

Switch

Future Systems

Red

Blue

Blue

Blue Blue

Blue

Blue

Blue

RedRed

Lt. Blue

Lt. Blue

Red – SpaceFibre (optical or copper)Blue – SpaceWireLt Blue – Local port interface (parallel)

Legend:

Hardware bridgeBetween SpaceWire

& SpaceFibre

• Same protocols supported across both physical interfaces SpaceWire and SpaceFibre

• Bridged by hardware router• Low-level protocols (RMAP &

GAP) for memory mapped DMA or single transactions – no software required & blurs enclosure boundaries

• Plug and Play network mapping and Change-of-Status indication supported in hardware

– Coming soon!

• Tunnel higher layer protocols


Advantages• One communications infrastructure

– Simplifies system design– Consists of 2 different physical layers

• SpaceWire• SpaceFibre• Bridged in hardware via routing switch

– Seamless integration

• Supports low-level & high-level protocols• Virtual serial backplanes

– RMAP & GAP

• Upper layer protocol may be identified– Via Protocol ID (PID)

• Low latency bus– Wormhole routing

• Side-Band signaling– Reducing number of interfaces– Time-Code enhancements

• Pending

• May be used as a time-triggered or event triggered bus– Time-triggered via Time-code defined slots

• Command bus features have been addressed• Cable redundancy (presented later)

– Transparent mechanism has been implemented» Proposed for standardization

• Data retries– Protocol ID (PID) can accommodate Retry protocols

» MIL-STD-1553 over SpaceWire (no PID assigned)» Reliable Data Delivery Protocol (RDDP) (no PID assigned)


System Engineer Toolkit

SpaceFiber (cell based virtual channels)•Long distance•Isolation•EMC/EMI•Bridge to SpW via hardware router

SpaceFiber•High Rate

Group Adaptive RoutingAcross multiple SpW links

•Dedicated link for low latency

•Buffers match packet size•Optimize throughput

•Multiple SpW local ports to prevent blocking; increase throughput

•Full Duplex•Cmd & Tlm opposite directions

CMDTLM•Redundant cables

•Router blockage prevention•Time-out•Max length

•Redundant paths

•Message sharing•Time-critical network•Consensus computing

•Time-codes •Near zero-jitter across entire network•Synchronization

•TDMA•1 pps

•Time-Code expansion•Interrupts•Polling•Multi-TimeCode

•Priority routing

Group Adaptive Routing

•Multiple SpW links


Conclusions• Simple protocol that is being developed from bottom up to

meet advanced spacecraft applications• One bus standard can meet requirements

– Real time control– Large data throughput– Safety

• Guaranteed Low latency• High reliability

• Reuse & reconfiguration of systems easier with standard interface– Modular functions with standard interface

• Serial interface– cable– backplane

• Provide system engineers more “tools” for more efficient designs

12006 MAPLD International ConferenceSpaceWire 101 Seminar NASA SpaceWire Architectures: Present &...

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