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

2. OMC-INTEGRAL Memory Management ADA Europe 2002 2 INTEGRAL International Gamma-Ray Astrophysics Laboratory 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)

3. 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)

4. 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.

5. OMC-INTEGRAL Memory Management ADA Europe 2002 5 OMC Optical 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

6. 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.

7. OMC-INTEGRAL Memory Management ADA Europe 2002 7 OMC OMC Components OMCAS FEE Camera Unit CSSW DPE HW Ground System Spacecraft SPIIBIS JEM-X OBDH DPE: 1750 Microprocessor MMU : Memory Management Unit CSSW : Common Service SoftWare (Ada 83) OMCAS : OMC Application Software (Ada 83) ASTRES: Operating System 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

8. 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

9. 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

10. 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.

11. OMC-INTEGRAL Memory Management ADA Europe 2002 11 OMCAS (OMC Aplication Software) Software Tasks Perform PHK: It is in charge of executing 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

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

13. OMC-INTEGRAL Memory Management ADA Europe 2002 13 Memory:Architectural Restrictions Total Memory 1 Mword (1 word= 2bytes) 16 data AS16 SW code AS 16 Logical Pages 1 Logical Page (4 Kwords) 1 Physical Page (4 Kwords) Task Static Association Memory available per task: 64Kwords

14. OMC-INTEGRAL Memory Management ADA Europe 2002 14. 16-BIT LOGICAL ADDRESS INSTRUCTION /OPERAND ACCESS DESIGNATOR FROM HARDWARE LOGICAL ADDRESS OF 4K PAGE AL E W P P A EW P P A PSAS PROCESSOR STATUS WORD 4 5 4 8 LOCK & KEY ACCESS PROTECT WRITE PROTECT (OPERAND ACCESS) 4 20-BIT PHYSICAL ADDRESS LPA 1212 4 A L ADDRESS OF WORD WITHIN 4K AS

15. 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 Not accessible Page Accessible Pages

16. OMC-INTEGRAL Memory Management ADA Europe 2002 16 Physical page 1 Low level memory management –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. Solution –Change, in a dynamic way, the Logical to Physical page association. Logical page type t_window is array (1..1024) of t_unsigned16 Physical page 2 Physical page 3 Logical page type t_window is array (1..1024) of t_unsigned16

17. OMC-INTEGRAL Memory Management ADA Europe 2002 17 CCD Charge 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)

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

19. 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

20. 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

21. OMC-INTEGRAL Memory Management ADA Europe 2002 21 Normal Mode

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

23. 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).