EDAC Concerns for Flight Software
and Hardware Design
Craig Pires
LADEE C&DH Lead
NASA-Ames Research Center
Moffett Field, CA
Craig.Pires@nasa.gov
Scott Christa
Karen Gundy-Burlet
Greg Limes
Larry Shackelford (GSFC)
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Mission Overview
• Lunar Atmosphere and Dust Environment
Explorer (LADEE) is a NASA mission that
will orbit the Moon and its main objective
is to characterize the atmosphere and
lunar dust environment.
– Low cost, minimal complexity and rapidly
prototyped “common bus” design.
– Model-Based Software Development
• Specific objectives are:
– Determine the global density,
composition, and time
variability of the lunar
atmosphere;
– Confirm the Apollo astronaut
sightings of dust jumps and
diffuse emission
– Laser Communications
Demonstration: 622 Mbs
Record download rate from the
Moon!
Clementine
spacecraft image of
moon dust corona
Gene Cernan’s
drawings of the lunar
sunrise
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Photo: Buddy Secor
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Photo: Bill Anderson
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Photo: Ben Cooper5
Frog Photobombed Launch!
This photo was taken by a still
camera which was on a sound
trigger at Pad 0B at WFF. The
photographer is Chris Perry of
the WFF Optical Systems
Group.
Photo went viral as soon as
released. Examples of
coverage:
http://www.cnn.com/2013/09/12/t
ech/innovation/frog-androcket/index.html?hpt=hp_c4
“Meet the Press”, on September
15, 2013
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Trajectory
• Phasing Loops
–
–
–
–
3 Perigee Manuevers
Time, Opportunity for Adjustments
Similar to past missions
(Clemintine, Wind WMAP)
• Lunar Orbit Insertion
–
–
First LOI for Capture
2 additional LOI lowering orbit
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Avionics C&DH
• 3U Compact PCI – Broad Reach
Active Memory
• BAE Rad750 128Mb
- Nibble Correct (64 Bit)
• Broad Reach DMOAB SDRAM Storage
- 1GB SECDED (32 Bit)
- 4 FAT16 Partitions*
(*Primary)
• Other C&DH Memory
– SRAM – Devices
– EEPROM & Flash – Program Storage
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Software Requirements
• Requirement Summary:
- Provide ability to enable/disable scrubbing
- Provide corrected/uncorrected memory error
counters and last error address
- Enable/Disable EDAC interrupts
- Provide corrected, uncorrected, and critical
error events
- Overwrite uncorrected memory error locations
to prevent continuous reporting
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Software Structure
• Flight Software built on CFE
• Separate Tasks
• Message Based
• Memory Scrub Task
• VxWorks Driver
• Handles Interrupts
• Silences Correctable and “Uncorrectable”
• MS Task
• Configures Drivers
• Records and Logs Events
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Experiences - Phasing Loops
• Orbital Position Plot
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Experiences - Phasing Loops
• Periapsis #1 Detail
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Experiences - Phasing Loops
• Periapsis #2 Detail
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Experiences - Phasing Loops
• Periapsis #3 Detail
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Lunar Orbit
• Normal Activity
– Average about 1 to 2 a Day
– Some Groups of Events
– Patterns or Locations
• “Uncorrectable” Errors
– Where in Memory
– Sensitive Spots
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Lessons Learned
• Events can happen fast in Groups
(May loose events due to rapid frequency)
• Van Allen Belt effects higher than
expected
• Events happen anywhere
– Groups of events at random times
– Multi-bit errors occurred far from Earth
• Unusual Events
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Lessons Learned - Improvements
• Mapping Locations by usage
– FAT Tables mapped out
– Reverse mapping on Addresses
– Exact location of data files (LLCD has helped)
• Improved logging of Events
• Better ways of injecting events during
testing
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