AAC Microtec Sirius OBC User Manual
Also see for Sirius OBC: User manual
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Document number 205065Version Rev EIssue date 2017-03-07Sirius OBC and TCM User Manualwww.aacmicrotec.com Page 93 of 131A watchdog is enabled in the TCM-S that must be kicked by the TCM-S Application or areset will occur.7.11. Mass Memory HandlingThe mass memory in TCM-S is intended for storage of telemetry data while awaiting transferto ground. To simplify divisions between different types of data with different configurations,the mass memory is divided into logical partitions. All data stored to mass memory is in theform of PUS packets ready for transmit to ground and are grouped together into segments.Each segment is of a fixed size (configurable for each partition) and is defined as startingwith a PUS packet. If stored PUS packets won't match the segment size exactly, theremaining bytes in each segment must be padded with a bit pattern of 0xF5 which will beremoved during download.Writing/Reading of data to/from a partition is provided by RMAP-commands. Downloading ofdata from a partition to ground is provided by a RMAP-command. See 7.14.1.20 and7.14.1.26 for further info.When a partition is full, there is no possibility to write data. When a partition is full, reading ordownloading of data from the partition must occur before new attempts to write data.Operations to modify read and write pointers of the partitions are provided by RMAP. See7.14.1.22 and 7.14.1.23 for further info.As the mass memory is flash-based, each new block will require erasing before acceptingwrites, but the TCM software will handle this automatically. For each 32-bit word stored inmass memory, there are 8 bits stored as EDAC to be able to detect double errors andcorrect single errors. During erases or writes, the operation may fail and the software willthen mark this block as bad and skip this in all future transactions. The bad block list isstored in NVRAM and will thus survive a reboot and/or power cycling. This gracefuldegradation behaviour of the mass memory implies that all partitions should be created withsome extra space to account for this phenomenon.7.12. ECSS standard serviceThe TCM-S supports a subset of the services described in [RD4]7.12.1. PUS-1 Telecommand verification serviceThe TCM-S performs a verification of APID of the incoming TC. If the verification fails, thetelecommand is rejected and a Telecommand Acceptance Failure - report (1,2) isgenerated as described in [RD4]. On successful verification, the command is routed to thereceiving APID. The receiving APID performs further verification of packet length, checksumof packet, packet type, packet subtype and application data and generates reportsaccordingly (1,1) or (1,2). If specified by the mission, the APID shall implement services forTelecommand Execution Started, Telecommand Execution Progress and TelecommandExecution Complete.Table 7-5: Telecommand Acceptance Report – Failure (1,2)Packet ID Packet Sequence Control CodeUINT16 UINT16 UINT8.0 – Illegal APID |
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