On Board Computer

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On Board Computer

• Generic OBC for small satellites

Karl Kaas Laursen, 10th sem. Control Engineering
Intelligent Autonomous SystemsAalborg
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The task at hand

• Design a generic on board computer for pico
  satellites

Goal

• Make it better, faster, smaller, cheaper,
  lighter, more integratable, testable, smaller,
  faster, lighter and better than preceeding pico
  satellite OBCs!

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How to start

• Define basic requirements (throw in all available
  buzzwords)
• Low power
• Low mass
• Low volume
• Lots of MIPS
• Large amount of memory
• Clean simple interfaces
• Easy to integrate
• Cheap - preferrably free

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First design steps

• Chose CPU architecture
• Candidates
• 80x86
• ARM
• XScale
• 8051
• SPARC
• 68000
• PowerPC
• Etc

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First design steps

• Chose CPU architecture
• Atmel ARM7 AT91R40807
• 40 MHz (36 MIPS)
• 32 bit
• 3.3V / low power
• Integrated memory controller
• Supported by eCos operating system
• Available on evaluation board

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Micro system architecture
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First obstacle SSETI-Express

• 1 A few adaptations to make it scalable

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First obstacle SSETI-Express

• 2 Add-on interface card to comply with fluffy
  interfaces

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This slide is censored!
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8 months later
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8 months later
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8 months later
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Design lessons from SSETI-Express

• Let the central system define the interfaces
• Freeze electrical interfaces EARLY
• Define datalink layer specific interfaces
• Throw out all processors in your OBC design
  except from main CPU
• Select a CPU that lets you do the above

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AAUSAT-II a new beginning

• Lets go to page one in the design

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AAUSAT-II a new beginning

• Stripping all the flashy blur

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AAUSAT-II a new beginning

• Engineering model PCB layout

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AAUSAT-II a new beginning

• Engineering model PCB layout

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• AAUSAT-II
• http//aausatii.aau.dk
• SSETI-Express OBC integration
• http//www.control.auc.dk/kkla01/obc_integration.
  pdf