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Jose Manuel Pérez Lobato Eva Martín Lobo

OMC - INTEGRAL Memory Management. Jose Manuel Pérez Lobato Eva Martín Lobo. INTEGRAL I nternational G amma- R ay A strophysics L aboratory. Spacecraft Description : International mission with the participation of all 14 member states of ESA .

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Jose Manuel Pérez Lobato Eva Martín Lobo

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  1. OMC - INTEGRAL Memory Management Jose Manuel Pérez Lobato Eva Martín Lobo

  2. INTEGRALInternationalGamma-RayAstrophysicsLaboratory • Spacecraft Description : International mission with the participation of all 14 member states of ESA . • Objective: Gather the most energetic radiation that comes from space (Gamma- ray). • Date of launch: October 2002. • Launcher:A Russian Proton rocket will place the spacecraft into orbit. • Time of use : 2 years ( Possible extension for up to 5 years) OMC-INTEGRAL Memory Management ADA Europe 2002

  3. INTEGRAL INSTRUMENTS • The SPECTROMETER (SPI) • The IMAGER (IBIS ) • The two X-RAY MONITOR (JEM-X) • The OPTICAL MONITORING CAMERA ( OMC) OMC-INTEGRAL Memory Management ADA Europe 2002

  4. INTEGRAL INSTRUMENTS • The SPECTROMETER (SPI) • Will perform spectral analysis of gamma-ray point sources and extended regions over an energy range between 20 keV and 8 MeV. • The Imager on Board the INTEGRAL Satellite (IBIS ) • Will give sharper gamma-ray images than any previous instrument, it will achieve a high angular resolution of 12 arcmin over an energy range between 15 keV and 10 MeV. • The Joint European X-Ray Monitor (JEM-X) • will make observations simultaneously with the main gamma-ray instruments and will provide images in the energy range of 3 - 35 keV. OMC-INTEGRAL Memory Management ADA Europe 2002

  5. OMCOptical Monitoring Camera • OMC offers the first opportunity to make long observations of the visible light coming from the gamma-ray and X-ray sources. • OMC is a CCD detector of 1024x 1024 pixels located in the top of the satellite. • It is sensitive to stars with a visual magnitude up to 19.7 OMC-INTEGRAL Memory Management ADA Europe 2002

  6. OMC Modes • Normal Mode : • Some windows to centre the image • Small windows of stellar objects. • Trigger Mode : • One big window for sporadic events (supernova explosion, stellar black hole) • Calibration Modes • Flat Field Calibration: • Extraction of large sections from the CCD in order to calibrate the CCD and detect damaged pixels. • Dark Current Calibration: • Extraction of sections on the left and right borders of the visible imaging area. OMC-INTEGRAL Memory Management ADA Europe 2002

  7. OMC OMCAS FEE DPE HW Camera Unit OBDH Spacecraft Ground System SPI IBIS JEM-X OMC Components • DPE: • 1750 Microprocessor • MMU : Memory Management Unit • ASTRES: Operating System • CSSW : Common Service SoftWare • (Ada 83) CSSW • OMCAS : OMC Application Software • (Ada 83) • FEE: Front-End Electronics • DPE-FEE Interface: • RS-422 serial lines (HSL,LSL) • Bi-level, ON/OFF commands • TM (Analogue channels) • OBDH: OMC <->Spacecraft • Communication Module OMC-INTEGRAL Memory Management ADA Europe 2002

  8. OMCAS(OMC Aplication Software) • Software Tasks • Collect TC : It is in charge of collecting and validating the incoming commands performing the syntax and sequence analysis OMC-INTEGRAL Memory Management ADA Europe 2002

  9. OMCAS(OMC Aplication Software) • Software Tasks • Control OMC : It is responsible for performing mode changes and all the related mode activities OMC-INTEGRAL Memory Management ADA Europe 2002

  10. OMCAS(OMC Aplication Software) • Software Tasks • Generate TM:It will pack the OMC telemetry provided by the different data transformations and will send it to the OBDH. OMC-INTEGRAL Memory Management ADA Europe 2002

  11. OMCAS(OMC Aplication Software) • Software Tasks • Perform PHK:It is in charge ofexecuting the tasks related to the periodic monitor (HouseKeeping Telemetry). The information is acquired once each TM cycle (8 sec.) and included in the TM packet OMC-INTEGRAL Memory Management ADA Europe 2002

  12. Extended Memory System Physical Memory 64 Kwords 256 Pages Address State (AS) 64 Kwords 16 AS 16 pages Logical Page= 4Kwords 1750 Address Space OMC-INTEGRAL Memory Management ADA Europe 2002

  13. Static Association Memory:Architectural Restrictions Total Memory 1 Mword (1 word= 2bytes) Task 16 data AS 16 SW code AS Task 16 Logical Pages 16 Logical Pages 1 Physical Page (4 Kwords) 1 Logical Page (4 Kwords) 1 Logical Page (4 Kwords) 1 Physical Page (4 Kwords) Memory available per task: 64Kwords OMC-INTEGRAL Memory Management ADA Europe 2002

  14. 20-BIT PHYSICAL ADDRESS LOCK & KEY ACCESS PROTECT WRITE PROTECT (OPERAND ACCESS) 4 8 AL P P A E W P P A A L EW 12 4 5 LPA 4 AS PS AS 4 PROCESSOR STATUS WORD . 16-BIT LOGICAL ADDRESS LOGICAL ADDRESS OF 4K PAGE ADDRESS OF WORD WITHIN 4K INSTRUCTION /OPERAND ACCESS DESIGNATOR FROM HARDWARE OMC-INTEGRAL Memory Management ADA Europe 2002

  15. Low level memory management • SW requirements: • To share data between AS (tasks ) • Reuse code  Store code in a physical page to be used by several tasks • Problem • There are 256 logical pages and 256 physical pages • If 2 logical pages are associated to 1 physical page, 1 physical page will not be accessible. Logical Pages Physical Pages Accessible Pages Not accessible Page OMC-INTEGRAL Memory Management ADA Europe 2002

  16. Low level memory management • Solution • Change, in a dynamic way, the Logical to Physical page association. Physical page 1 • The solution implies to change the values of the MMU registers • It should be programmed in assembler. • The data structure defined in ADA is the “filter” to access to the physical memory. Changing the association implies that a single register is used to access to several parts of the memory. Logical page type t_window is array (1..1024) of t_unsigned16 Physical page 2 Logical page type t_window is array (1..1024) of t_unsigned16 Physical page 3 OMC-INTEGRAL Memory Management ADA Europe 2002

  17. CCDCharge Copled Device • Structure: • Visible area: 1024x1024 visible pixels + several non visible lines • Hide area : storage area ,same size visible area, • Working algorithm: • Image exposure for a TC time • Transmit the Visible Area -->> Hide Area • Digitalize the individual pixels values and transmit them to the memory processor • Restriction: • Images can not be more than10 seconds at the Hide Area 1 pixel =16 bits (12 useful) OMC-INTEGRAL Memory Management ADA Europe 2002

  18. Visible Area Hiden Area CCD Graphic Diagram A/D A/D OMC-INTEGRAL Memory Management ADA Europe 2002

  19. OMC Working modes • Normal Mode : • 10 windows of 31x31 pixels to centre the image • 400 windows of variable size from 5x5 to 11x11 pixels each one • Trigger Mode : • 1 window of 100x100 pixels. • Calibration modes : • High size window => • Use all the available memory and • Change the Logical---Physical page association OMC-INTEGRAL Memory Management ADA Europe 2002

  20. Window extraction 1.- Order windows by its position in the CCD 2.- Extract 8 lines from the CCD ( 8 x1024 words = 2 pages) 3.-Get the pixels of each window, discarding the 4 non useful bits of each pixel 4.-Transfer the windows to the TM memory pages marking them as empty, half-full or full 5.-Construct TM packets TM task and Science Task share physical pages OMC-INTEGRAL Memory Management ADA Europe 2002

  21. CCD STORAGE AREA RAM DPE Physical Pages TELEMETRY TASK Address State Logical Pages SCIENCE TASK Address State 1 80 1 2 3 4 Logical Pages 1 1 40 41 39 5 6 40 2 2 1 2 3 4 41 80 10 1 2 3 4 8 9 7 5 6 3 6 3 40 5 4 5 6 2 3 40 8 rows HSSL 4 10 ROE FIFO Normal Mode OMC-INTEGRAL Memory Management ADA Europe 2002

  22. Full Full RAM DPE Free Physical Pages FFCAL TASK Address State TELEMETRY TASK Address State CCD STORAGE AREA Free Logical Pages 1 1 2 Logical Page 4K bytes 2 HSSL 3 ROE FIFO FF Calibration Mode OMC-INTEGRAL Memory Management ADA Europe 2002

  23. Conclusions • Solution approved by ESA engineers and included in the CSSW module in order to all instruments could use it. • In Embedded Systems low level restrictions define high level design solutions. • Experience acquired will be reused in future projects (Eddington). OMC-INTEGRAL Memory Management ADA Europe 2002

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