Jose Manuel Pérez Lobato Eva Martín Lobo

INTA

Jose Manuel Pérez LobatoEva Martín Lobo

OMC - INTEGRAL

Memory Management

OMC-INTEGRAL Memory Management ADA Europe 2002

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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)


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INTEGRAL INSTRUMENTS

• The SPECTROMETER (SPI) • The IMAGER (IBIS )

• The two X-RAY MONITOR

(JEM-X)

• The OPTICAL MONITORING CAMERA

( OMC)


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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.


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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


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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.


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OMC

OMC Components

OMCAS

FEE

Camera Unit

CSSW

DPE HW

Ground System

Spacecraft

SPI IBIS JEM-X

OBDH

•DPE:1750 MicroprocessorMMU : 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


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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

1CollectTC

2ControlOMC

3Generate

TM

4PerformPHK

tc

validtc

rawtm

mode

sc

tc_info

hk_tm

hk pm_cmd

tm

roe_cmd

control_omc_tm

ccd_tm


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• Software Tasks• Control OMC : It is responsible for performing mode changes and all

the related mode activities

1CollectTC

2ControlOMC

3Generate

TM

4PerformPHK

tc

validtc

rawtm

mode

sc

tc_info

hk_tm

hk pm_cmd

tm

roe_cmd

control_omc_tm

ccd_tm


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• Software Tasks• Generate TM: It will pack the OMC telemetry provided by the

different data transformations and will send it to the OBDH.

1CollectTC

2ControlOMC

3Generate

TM

4PerformPHK

tc

validtc

rawtm

mode

sc

tc_info

hk_tm

hk pm_cmd

tm

roe_cmd

control_omc_tm

ccd_tm


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• 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

1CollectTC

2ControlOMC

3Generate

TM

4PerformPHK

tc

validtc

rawtm

mode

sc

tc_info

hk_tm

hk pm_cmd

tm

roe_cmd

control_omc_tm

ccd_tm


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1750 Address Space

PhysicalMemory

64 Kwords

256

Pages

LogicalPage=4Kwords

Extended MemorySystem

16 AS

AddressState(AS)

64 Kwords

16 pages


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Memory:Architectural Restrictions

Total Memory1 Mword(1 word= 2bytes)

16 data AS 16 SW code AS

16 Logical Pages

16 Logical Pages

1 Logical Page (4 Kwords)

1 Logical Page (4 Kwords)

1 Physical Page (4 Kwords)

1 Physical Page (4 Kwords)

Task Task

Static Association

Memory available per task: 64Kwords


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.

16-BIT LOGICAL ADDRESS

INSTRUCTION /OPERAND ACCESS DESIGNATOR FROM HARDWARE

LOGICAL ADDRESS OF 4K PAGE

AL E WP P A

EW P P A

PS AS

PROCESSOR STATUS WORD

4

5

4

8

LOCK & KEY ACCESS PROTECT WRITE PROTECT

(OPERAND ACCESS)4

20-BIT PHYSICAL ADDRESS

LPA

124

A L

ADDRESS OF WORD WITHIN 4K

AS


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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


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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 pagetype t_window is

array (1..1024) of t_unsigned16

Physical page 2

Physical page 3

Logical pagetype t_window is

array (1..1024) of t_unsigned16


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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)


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A/DA/D

VisibleArea

HidenArea

CCD Graphic Diagram


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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


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Window extraction1.- 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


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Normal Mode

RAM DPE

SCIENCE TASKAddress State

Logical Pages

TELEMETRY TASK Address StateLogical Pages

Physical Pages

1

2

3

10

80

2

1

3

4

1 2 3 4

5 640

1 2 3 4

5 6

40

41

HSSL

CCD STORAGE AREA

1 25

3

679

41

ROE FIFO

8 rows

4

8

3940

10

80

1 2 3 4

5 6

40


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FF Calibration Mode

CCD STORAGE AREA

ROE FIFO

RAM DPE

FFCAL TASKAddress State

1

2 Logical Page

TELEMETRY TASK Address State

Physical Pages

4K bytes

HSSL

2

1

3

Logical Pages

Full

FullFree

Free


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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).

Documents

Jose Manuel Pérez Lobato Eva Martín Lobo