Onboard CORBA Studies Project Review Kevin Rice GST/NASA-GSFC Code 588 April 2001
Project Phases
• Phase 1– Port satellite flight software to CORBA
• Phase 2– Port “micro” CORBA to flight u-controllers– Connect u-controllers & main CPUs via PPP over
MUX-1553 bus, using CORBA• Phase 3
– Develop “ground to space” CORBA experiment in lab environment
– Possibly team with Science System Ltd (Plc) for flight experiments on UoSat-12
GSFC Flight Software Heritage
MAP 6/01?
XTE 12/95 TRMM 11/97 FUSE 6/99
SAMPEX 7/92 FAST 8/96 SWAS 12/98 TRACE 12/97WIRE 3/99
TRIANA ???
Architecture:!ANSI C!1 main flight computer! several u-controller sub-systems!1553/1773 ‘network’!VxWorks
Architecture:!C++!1 main flight computer!VxWorks
Use MAP Flight Software
• Microwave Anisotropy Probe• Follow on to COBE• Measures the cosmic micro-wave
background radiation in the Universe• Will launch in early summer 2001• Well understood by GSFC flight software
branch & largely finished…• Written in ANSI C
RT
R000
RT
R000
RT
R000Power RSN HouseKeeping
RSNTransponder
RSN(A)BC
Mongoose-V
MAC Processor
(A)
1773 Bus
MSSP
MAP Hardware Architecture Diagram (Simplified)
IRU
CSS
DSS
RWA
PCS
R000
RTRTACE
Custom I/O
ACERSN (A)
R000
RT
DEURSN
Sensors
•~12-14Mhz•32MB of “program memory”•256 MB recorder storage,•VxWorks
•Harvard Architecture•64K IRAM•64KDRAM•Custom RSN-OS•( 160k, 1MB of IRAM possible)1553/1773
MUX BusInterconnect
Basically a Distributed Architecture
Ground System
Phase 1: MAP Software Architecture Overview
1773
Medium Speed SerialLine
MAC Processor
Software Bus
Time Code Task
1773 Bus Controller Task
Checksum Task
Command Ingest Task
Mem. Scrub Task
Memory Dwell Task
Ephemeris Task
Attitude Control Task
Instrument Support Task
Data Storage Task
Telemetry Output Task
Telem. & Stat. TaskHealth &
Safety Task
Stored Command Task
CMD & Tel.
Transponder Power Attitude Control Housekeeping Digital Sensor Input
XRSN PSERSN ACE HK DEU
The SBUS is used as
the message passing
“channel”
MSG
MSG
MSG
Phase 1: CORBA PORT
1773
Medium Speed SerialLine
NT Processor
RT Events
Time Code Task
Checksum Task
Command Ingest Task Mem. Scrub
Task
Memory Dwell Task
Ephemeris Task
Attitude Control Task
Instrument Support Task
Data Storage Task
Telemetry Output Task
Telem. & Stat. TaskHealth &
Safety Task
Stored Command Task
CMD & Tel.
Replaced SBUS with TAO Real-time Event
Channel
1773 Bus Controller Task
Transponder Power Attitude Control Housekeeping Digital Sensor Input
XRSN PSERSN ACE HK DEU
Actually ported Linux PORT of
MAP to CORBA, on NT
CMD & Tel.
MSG
Ground System
MSG
MSG
Phase 2: Use Micro-CORBA ORB
• Science Systems Ltd (Plc) developed a small flight ORB for their RATE experiment
• RATE flew on the STRV-1b satellite last fall with goal of testing CORBA “calls” ground to space…
• Unfortunately, the STRV-1b failed shortly after launch…
• The RATE ORB can be configured to 5-20k depending on desired functionality.
• BUT it is NOT a full featured ORB, or necessarily 100% CORBA compliant…
Phase 2: Port Micro-CORBA to RSNs
• Science System agreed to provide binary version of CORBA using our cross-compilers
• Run PPP over 1553/1773 bus to provide “network” link…
• Map GIOP over PPP, or use GIOP+TCP+PPP if limited address space permits (easiest)
Phase 2: Micro-CORBA + GIOP + PPP
1773
Medium Speed SerialLine
MAC Processor
RT Events/RMI?
Time Code Task
1773 Bus Controller Task
Checksum Task
Command Ingest Task
Mem. Scrub Task
Memory Dwell Task
Ephemeris Task
Attitude Control Task
Instrument Support Task
Data Storage Task
Telemetry Output Task
Telem. & Stat. TaskHealth &
Safety Task
Stored Command Task
CMD & Tel.
Transponder Power Attitude Control Housekeeping Digital Sensor Input
XRSN PSERSN ACE HK DEU
PPP
Ground System
MSG
MSG
MSG
Use micro-ORB here, RTEMS, plus 1MB
of ram
Continue using
ACE/TAOhere
Use 50% of 1553 as serial stream for PPP
Phase 3: CORBA Ground to Space
• Develop in lab “flat sat” test bed to simulate ground to space CORBA
• Possibly experiment with simulated link delays and alternative protocol suites– TCP, SCPS-TP, CCSDS (using ORB level re-
transmission of GIOP?)• Team with Science Systems Ltd on RATE
“2”, using UoSAT-12
Phase 3: CORBA Ground to Space Concept
End-User ORBControl Center ORB(s)ORB Bridge?
Protocol Gateway?
Flight ORB
TCP/IPTCP/IP
GIOPGIOP
TCP or SCPS-TP
CORBA
TCP/IIOP
SCPS-TP?
GIOP
ORB Router?
Phase Status
• Phase 1:– Complete, but limited testing…
• Phase 2:– Currently working w/OAR Inc, to port RTEMS-OS to
u-controller, RTEMS can be configured to 32-120K with TCP stack (An RSN 160KB, or 1MB will need to be used…)
– July ’01 to start work w/SSL to port micro-ORB • Phase 3:
– SSL secured funding with BNSC for UoSat-12 experiments
– NASA-GSFC seeking funding…