SPIRE Design Description - Research Services

Draft SPIRE Design Description Document
Onboard Software: The CPU board carries in the PROM the basic software to drive and control the DPU.
The tasks the OBS carries out are schematically shown in Figure 4-6.
Telecommands
CDMS OBS
Housekeeping
Data
Telemetry
Science
Data
Subsystem
Control
Unit
Commands
61
Housekeeping
Data
Science
Data
Commands
Housekeeping Data
Science Data
Mechanism
Control
Unit
Figure 4-6 SPIRE DPU On Board Software Context Diagram
Commands
Detector
Control
Unit
The main functions of the OBS are the:
(i) acceptance of instrument commands from CDMS;
(ii) execution of predefined commanding sequences;
(iii) instrument health/status monitoring;
(iv) implementation of pre-defined procedures on detection of instrument anomalies. When an anomaly
occurs, the OBS either (i) adjusts the instrument operation parameters, and/or (ii) switches the
operating mode and/or (iii) activates subsystem redundancy;
(v) science data acquisition and packetisation;
(vi) HK data packetisation;
(vii) transmission of data (science, HK, events and telecommand verification) from the instrument to the
CDMS.
In addition, the OBS shall provide the following software oriented functions:
(i) the ability to load, via telecommands, replacement and/or additional software (patches, tables,
command sequences);
(ii) self-test and software verification facilities;
(iii) the possibility to load and dump part of DPU/DCU memory;
(iv) the possibility to write and check EEPROM;
(v) the possibility to inhibit these functions during flight operations.
4.1.2 Detector Readout and Control Unit (HSDRCU)
The DRC is an electronic unit housed into two boxes: the FCU and the DCU, located between the FPU and
the DPU. The DRCU includes the front-end electronics of the following sub-systems:
(i) BDAs,
(ii) SMEC,
(iii) Beam Steering Mirror,
(iv) Cooler,
(v) PCAL and SCAL,
(vi) Thermometry & Analog Housekeeping,