Document number
205065
Version
Rev. N
Issue date
2019-02-04
Sirius OBC and TCM User Manual
Page
119
of
174
AVAILABLE is set by signal Carrier lock in and the flag NO BIT LOCK is set by signal Sub-
carrier lock in.
7.7. Time Management
The TCM-S has an internal SCET timer that can be synchronised to an external time source.
In order for synchronisation to occur, a stable PPS input must first be provided for at least 7
seconds, after which the PPS will be considered “qualified” and the TCM
-S will automatically
sync SCET subseconds to the external PPS arrival time. A received SCETTime write
command can then synchronise the seconds value, see 7.12.4.17.
If the PPS is not stable, the TCM-S will abort synchronisation to the external source and will
attempt to re-qualify the PPS. When the PPS is not qualified, neither subseconds nor
seconds synchronisation will occur.
The current criteria for stability is set to be extremely generous, and only after a PPS interval
of 2 seconds or more will the PPS be considered unstable by the TCM-S.
7.7.1. TM time stamps
A timestamp can be generated when a TM Transfer Frame is sent on VC0. The rate of
timestamp generation is configurable through an RMAP command and the latest timestamp
is readable on the same interface. See 7.12.4.11 and 7.12.4.12 for further info.
7.8. Error Management and System Supervision
The Error Manager in the TCM-S provides information about different errors and operational
status of the system such as:
•
EDAC single error count
•
EDAC multiple error count
•
Watchdog trips
•
CPU Parity errors.
Error Manager related information and housekeeping data is available by RMAP. See
7.12.4.16
The status of the TM Downlink and TC Uplink are available through RMAP. See 7.12.4.14
and 7.12.4.1
A watchdog is enabled in the TCM-S that must be kicked by the TCM-S Application or a
reset will occur.
7.9. Mass Memory Handling
The mass memory in the TCM-S is primarily intended for storage of telemetry data while
awaiting transfer to ground, but can also be used for internal data storage. The mass
memory is configurable as described in chapter 7.4
The mass memory is accessed through RMAP commands as described in chapters
7.12.4.19 to 7.12.4.26. The mass memory is nandflash-based and that also slightly colours
its user interface, even though the detailed handling has been abstracted away. The primary
storage units in a flash are the block of 2097152 bytes, i.e. 2 Mbytes, and the page of 16384