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A Study On Different 32 And 16-bit Processors For Low-Earth Orbit Space Applications

A Study On Different 32 And 16-bit Processors For Low-Earth Orbit Space Applications. Krister Sundström Master’s Project. Background Data. Low-Earth Orbit: 400 - 600 km altitude Short Lifetime: ~ 3 years Small-Satellite Constellation: ~ 60 kg/satellite >100 satellites.

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A Study On Different 32 And 16-bit Processors For Low-Earth Orbit Space Applications

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  1. A Study On Different 32 And 16-bit Processors For Low-Earth Orbit Space Applications Krister Sundström Master’s Project 2000-10-11 RYP-KS

  2. Background Data • Low-Earth Orbit: 400 - 600 km altitude • Short Lifetime: ~ 3 years • Small-Satellite Constellation: ~ 60 kg/satellite >100 satellites 2000-10-11 RYP-KS

  3. Background Information • On-Board Computer Systems (OBC) • Real-Time Systems (RTS) • Single Event Effects (SEE) • Parasitic Silicon Controlled Rectifier • Interrupt Phillosophy 2000-10-11 RYP-KS

  4. Data Handling System • Central Part of The Satellite • Mission Software • Subsystem Master • Shared Processing Power 2000-10-11 RYP-KS

  5. Study Topics • Availability • ErrorToleranceAndRecovery • Error Detection And Correction (EDAC) • Watchdog 2000-10-11 RYP-KS

  6. Study Topics • Peripheral Support • Serial & parallel ports / Bus controllers • Memory types • Multitask Support • Real-time system • Context switching • Processor Architectures 2000-10-11 RYP-KS

  7. What Is A Real-Time System? • Correct functionality, at the right time Soft RTS • Instrument Data Collection • Missed Soft Deadline  • System still functional • Some degradations Hard RTS • Attitude & Orbit Control System (AOCS) • Missed Hard Deadline  • Catastrophe may follow 2000-10-11 RYP-KS

  8. A Simple Memory Cell Model Single Event Effects (cont.) 2000-10-11 RYP-KS

  9. Single Event Effects (cont.) • Spread Out Data Bits • Less risk for multiple bit error 2000-10-11 RYP-KS

  10. Parasitic SCR SCR - Silicon Controlled Rectifier • Can Cause Permanent Damage • Single Event Latch-up • Single Event Burn-out (SEB) • Current Limiter • Silicon On Insulator (SOI) 2000-10-11 RYP-KS

  11. Checkbit Generator = EDAC (cont.) 2000-10-11 RYP-KS

  12. Interrupts • Masked • Threshold 2000-10-11 RYP-KS

  13. Different Processors • RH Thor (32)Saab Ericsson • ERC32 (32)Temics • Leon (32)ESA • HS-RTX2010 RH (16)Harris 2000-10-11 RYP-KS

  14. 1 Giby = 230 bytes RH Thor • 32-bit, 4-Stage Pipelined RISC Processor • 2 Giby Address Space 2000-10-11 RYP-KS

  15. RH Thor (cont.) • Hardware Support For Task Switching • Exception  Resume • SOI – Silicon On Insulator 2000-10-11 RYP-KS

  16. I/O IU MC FPU DMA ERC32 • Fully SPARC v7 Compatible • 3 Main Blocks; IU, MC, FPU 2000-10-11 RYP-KS

  17. 1 Miby = 220 bytes ERC32 • 32 Miby Address Space • Multitask Support – Windows Register File 2000-10-11 RYP-KS

  18. Leon • Open-sourced – Free VHDL Code • Small Design – 30 kGates (without FPU) • 100% ERC32 Compatible • Fully SPARC v8 Compatible 2000-10-11 RYP-KS

  19. Leon (cont.) • Many On-Chip Peripheral Interfaces • 1 Giby Address Space • Multitask Support 2000-10-11 RYP-KS

  20. HS-RTX2010 RH • Small, Well Used 16-bit Processor • High Radiation Tolerant (>300 kRAD) • 1 Miby Address Space 2000-10-11 RYP-KS

  21. Why Leon? • Open-sourced architecture • Free VHDL-code • Optimisation • On-chip add-on possibilities • Small design • Only 27’000 gates + RAM 2000-10-11 RYP-KS

  22. Why Leon? (cont.) • Re-Configurable • Fully SPARC v8 Compatible 2000-10-11 RYP-KS

  23. Disadvantages With Leon? • No Support For Integer Division • DIVU – unsigned division • DIVS – signed division • New Design 2000-10-11 RYP-KS

  24. - The End - www.acc.umu.se/~moschler/x2000 2000-10-11 RYP-KS

  25. OBC Tasks • Processing of Uplink Telecommand (TC) Data Stream • Assemble, decode, and distribute incoming telecommands • Generate Downlink Telemetry (TM) Data Stream • Collect telemetry data • Generate TM frames • Provide General I/O for Command Distribution and Telemetry Data Collection 2000-10-11 RYP-KS

  26. OBC Tasks (cont.) • Provide Processing Power for Various Tasks • Battery charging control • Calculations for non-intelligent payload • Antenna pointing (attitude controlling) • Payload and thermal control • Provide With Timing Functionalities • On-Board Timer (OBT) counter • Time pulse synchronisation, by using GPS receivers • Queuing of internal spacecraft commands 2000-10-11 RYP-KS

  27. OBC Tasks (cont.) • Provide With Autonomy Functionalities • System supervision and context switching (OS aspects) • Automatic system reconfiguration in case of system error(s) • Automatic spacecraft recovery (Sun & Earth) • Bus Controlling and Peripheral Communications • Bus master • Instrument/ Payload interfacing 2000-10-11 RYP-KS

  28. Single Event Effects • Incoming Particles • Single Event Upset (SEU) • Single Event Latch-up (SEL) • Other Single Event Phenomena (SEP) • Technology Dependent • Silicon Wafers vs Silicon On Isolator (SOI) 2000-10-11 RYP-KS

  29. What Is A Real-Time System? “The correctness of a real-time system depends not only on the logical result of the computation but also on the time at which the results are produced.” – [RTSAPL] • Correct functionality, at the right time 2000-10-11 RYP-KS

  30. EDAC Error Detection And Correction • Scrubbing • Hamming Code d(min) = s + t + 1 (I) d(min) = 2 t + 1 (II) 2000-10-11 RYP-KS

  31. Data Flow A Typical Data Handling System 2000-10-11 RYP-KS

  32. ToDo • Förklara: • SCR • P/L egen intelligens som klarar sig självt, fristående från OBC. Bara busstrafik mellan • Realtidssystem och deras hårda och mjuka tidskrav • Att DHU och OBC är tätt sammanfogade i småsatelliter och att de här tituleras OBC • Hur EDAC fungerar • Förslag på EEPROM uppsättnigar och resten av ett OBDH. Kolla in WALT-projektet • Olika interruptfilosofier, typ Masked, Threshold, etc • Atomic Actions? • Pipeline • In 1950, a smart guy named Richard W. Hamming figured out a method of implementing ECC memory using the theoretical minimum number of redundant bits (this is called the Hamming Code). • FPGA • En bild på olika bitorganiseringar I minnen 2000-10-11 RYP-KS

  33. 2000-10-11 RYP-KS

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