INTA
OMC - INTEGRAL
Memory Management
Jose Manuel Pérez Lobato
Eva Martín Lobo
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 (Gammaray).
• 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
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INTEGRAL INSTRUMENTS
• The SPECTROMETER (SPI)
• The IMAGER (IBIS )
• The two X-RAY MONITOR
(JEM-X)
• The OPTICAL
MONITORING CAMERA
( OMC)
OMC-INTEGRAL Memory
Management
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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.
OMC-INTEGRAL Memory
Management
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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
OMC-INTEGRAL Memory
Management
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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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Management
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OMC Components
OMC
•ASTRES: Operating System
OMCAS
CSSW
DPE HW
FEE
Camera
Unit
OBDH
Ground
System
Spacecraft
SPI
IBIS
•DPE:
1750 Microprocessor
MMU : Memory Management Unit
JEM-X
•CSSW : Common Service SoftWare
(Ada 83)
•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
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Management
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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
roe_cmd
valid
tc
tc
mode
sc
ccd_tm
1
Collect
TC
2
Control
OMC
control_omc_tm
3
Generate
TM
tm
tc_info
raw
tm
hk_tm
hk
4
Perform
PHK
pm_cmd
OMC-INTEGRAL Memory
Management
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OMCAS
(OMC Aplication Software)
• Software Tasks
• Control OMC : It is responsible for performing mode changes and all
the related mode activities
roe_cmd
valid
tc
tc
mode
sc
ccd_tm
1
Collect
TC
2
Control
OMC
control_omc_tm
3
Generate
TM
tm
tc_info
raw
tm
hk_tm
hk
4
Perform
PHK
pm_cmd
OMC-INTEGRAL Memory
Management
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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.
roe_cmd
valid
tc
tc
mode
sc
ccd_tm
1
Collect
TC
2
Control
OMC
control_omc_tm
3
Generate
TM
tm
tc_info
raw
tm
hk_tm
hk
4
Perform
PHK
pm_cmd
OMC-INTEGRAL Memory
Management
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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
roe_cmd
valid
tc
tc
mode
sc
ccd_tm
1
Collect
TC
2
Control
OMC
control_omc_tm
3
Generate
TM
tm
tc_info
raw
tm
hk_tm
hk
4
Perform
PHK
pm_cmd
OMC-INTEGRAL Memory
Management
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1750 Address Space
Extended Memory
System
Physical
Memory
64
Kwords
256
16
AS
Pages
Address
State 16
(AS) pages
64 Kwords
Logical
Page=
4Kwords
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Management
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Memory:Architectural Restrictions
Total Memory
1 Mword
(1 word= 2bytes)
Task
1 Physical Page
(4 Kwords)
16 data AS
16 SW code AS
16 Logical
Pages
16 Logical
Pages
1 Logical Page
(4 Kwords)
1 Logical Page
(4 Kwords)
Task
1 Physical Page
(4 Kwords)
Memory available per task: 64Kwords
Static Association
OMC-INTEGRAL Memory
Management
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LOCK & KEY
ACCESS
PROTECT
20-BIT PHYSICAL ADDRESS
WRITE PROTECT
(OPERAND ACCESS)
4
.
8
AL
P P A
EW
4
AL
EW
P PA
4
1
2
5
PS
AS
AS
PROCESSOR STATUS WORD
16-BIT
LOGICAL
ADDRESS
LPA
4
INSTRUCTION
/OPERAND ACCESS
DESIGNATOR FROM
HARDWARE
OMC-INTEGRAL Memory
Management
LOGICAL
ADDRESS
OF
4K
PAGE
ADDRESS OF
WORD WITHIN
4K
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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
Accessible Pages
Not accessible
Page
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Management
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Low level memory management
• Solution
– Change, in a dynamic way, the Logical to Physical page
association.
– 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.
OMC-INTEGRAL Memory
Management
Physical page 1
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
16
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)
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Management
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CCD Graphic Diagram
Visible
Area
Hiden
Area
A/D
A/D
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Management
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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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Management
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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
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Management
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Normal Mode
CCD STORAGE AREA
RAM DPE
SCIENCE TASK
Address State
80
40
41
1
1 2
Logical
Pages
1
39
Physical Pages
5
3
TELEMETRY TASK
Address State
Logical Pages
4
6
40
2
2
1 2
41
10
7
2
3
3
4
4
80
4
5 6
3
6
5
1
1 2
8
9
3
5 6
3
40
40
8 rows
4
HSSL
10
ROE FIFO
OMC-INTEGRAL Memory
Management
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FF Calibration Mode
RAM DPE
FFCAL TASK
Address State
CCD STORAGE AREA
Logical
Pages
Physical
Pages
TELEMETRY TASK
Address State
1
Full
Free
1
2
Full
Free
Logical Page
4K bytes
2
HSSL
3
ROE FIFO
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Management
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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).
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Management
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