Document number
205065
Version
Rev. N
Issue date
2019-02-04
Sirius OBC and TCM User Manual
Page
108
of
174
7. Sirius TCM
7.1. Description
The Sirius TCM handles receiving of Telecommands (TCs) and Telemetry (TM) as well as
Spacewire communication using the RMAP protocol.
TC, received from ground, can be of two command types; a pulse command or a
Telecommand. A pulse command is decoded directly in the hardware and the hardware then
sets an output pin according to the pulse command parameters. All other commands are
handled by the Sirius TCM
software. Any command not addressing the Sirius TCM will be
routed to other nodes on the SpaceWire network according to the current Sirius TCM
configuration.
TM is received from other nodes on the SpaceWire network. The Sirius TCM supports both
live TM transmissions directly to ground as well as storage of TM to the Mass Memory for
later retrieval or download to ground during ground passes.
The Sirius TCM is highly configurable to be adaptable to different customer needs and
missions and currently supports SpaceWire (SpW) using the Read Memory Access Protocol
(RMAP), UART interfaces, pulse commands as well as Telecommand and Telemetry using
CCSDS frame encodings and ECSS PUS packets.
The default configuration of the TM downlink is:
•
FECF is included in TM transfer frames.
•
Master Channel Frame counter is enabled for telemetry.
•
Generation of Idle frames is enabled.
•
Pseudo randomization of telemetry is enaled.
•
Reed Solomon encoding of telemetry is enabled.
•
Convolutional encoding of telemetry is disabled.
•
The divisor of the TM clock is set to 25.
•
All available interrupts from the CCSDS IP are enabled.
•
Generation of OCF/CLCW in TM Transfer frames is enabled.
•
TM is enabled.