MA28140 Datasheet, PDF (5/72 Pages) Dynex Semiconductor – Packet Telecommand Decoder

MA28140
PACKETISATION
LAYER
SEGMENTATION
LAYER
PACKET
HEADER
EXAMPLE : 256 OCTETS
PACKET
DATA
PACKET
ERROR
CONTROL
1 OCTET
SEGMENT
HEADER
248 OCTETS
FIRST PACKET
SEGMENT
1
SEGMENT
HEADER
8
LAST PACKET
SEGMENT
TRANSFER
LAYER
5
FRAME
HEADER
249 (MAX.)
FRAME DATA
FIELD
2
FRAME
ERROR
CONTROL
5
9
2
FRAME
FRAME DATA
FRAME
ERROR
HEADER
FIELD
CONTROL
CODING
LAYER
(CODEBLOCK
LENGTH = 8
OCTETS)
2
START
SEQUENCE
7
1
INFOR- ERROR
MATION CONTROL
CODEBLOCK
No.1
7
1
E.C.
CODEBLOCK
No.2
1
7
1
4
3
1
8
E.C.
E.C.
FILL
E.C.
TAIL
SEQUENCE
CODEBLOCK
No.36
CODEBLOCK
No.37
PHYSICAL
LAYER
(ESA PLOP-2)
16 OCTETS
ACQUISITION
SEQUENCE
306 OCTETS
FIRST CLTU
MIN. 1 OCTET
IDLE SEQUENCE
34 OCTETS
LAST CLTU
IDLE SEQUENCE
(OPTIONAL)
Figure 3: CCSDS Protocol Layer Architecture
COMMAND PULSE DISTRIBUTION UNIT
The CPDU is integrated into the PTD ensuring higher
reliability for this critical function (direct telecommand for
spacecraft reconfiguration) than if implemented in an external
chip. The critical commands executed by the CPDU are
received in specific packets. The CPDU responds to the MAP
identifier 0, and to a mission dependent application process
identifier (stored in ROM). No segmentation is accepted, the
commands must be contained in an unsegmented package.
The unit generates a reporting word (CPDU Status = 16 bits).
BUS CONTROLLER
This block is the interface between external memories and
on chip modules. Its different functions are:
• address decoding.
• internal and external bus access arbitration.
TELEMETRY MODULE
This block is the interface with the telemetry subsystem. It
manages the data report storage using double buffered
registers.
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