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THEMIS INSTRUMENT TRAINING IDPU

THEMIS INSTRUMENT TRAINING IDPU. Overview. Introduction The IDPU is the instrument interface to the spacecraft. There are 3 main boards in the IDPU The Low Voltage Power Supply takes the spacecraft provided 28V and converts it into the voltages required by the instruments.

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THEMIS INSTRUMENT TRAINING IDPU

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  1. THEMIS INSTRUMENT TRAINING • IDPU

  2. Overview • Introduction • The IDPU is the instrument interface to the spacecraft. • There are 3 main boards in the IDPU • The Low Voltage Power Supply takes the spacecraft provided 28V and converts it into the voltages required by the instruments. • The Power Control Board switches the supplies to the instruments and provides some over current protection. It also switches the spacecraft supplied Actuator supply to the mag booms / EFI. • The Data Control Board contains the processor and memory where the instrument data is stored before being telemeted to the spacecraft.

  3. Overview • IDPU also has most of the electronics for the other instruments – the FGM (FGE), EFI (BEB & DFB), SST (DAP) as well as the particle instrument data processing board (ETC).

  4. IDPU Photo DAP BEB DFB DCB PCB LVPS Data Interface Power Supply Interface Actuator Supply Interface

  5. IDPU Power On • On power on of the IDPU: • The reset counter will display a random number until cleared by the IDPUCLEAR command. • The FSW version will read 0x21. This the version of software in the one time programmable PROM. If there is a ‘good’ program in the EEPROM it will be loaded. The FSW version will then change. Currently this is version 0x42. • The IDPU starts in SAFE mode

  6. IDPU Modes IDPU Init Script clears errors and puts the IDPU in Normal Mode. IDPU MODES SAFE – default on power up, and mode before power down. NORMAL – standard operating mode, enables instrument switching. ENGINEERING – Deployment mode, for EFI and Mag Boom deployment & ESA cover opening. LOW POWER – All instruments off except FGM.

  7. Instrument Power On Before powering on an Instrument the switched needs to be enabled. Then the Instrument can be powered on.

  8. IDPU Voltages Instrument Voltages FGM: +2.5VD, +5VD, ±5VA, ±8VA SCM: ±10VA (also requires EFI to be powered) EFI: No voltage monitors, only total EFI board, and individual axis floating supply current monitors. SST: +2.5VD, +5VD, ±5VA ESA: +28V, ESA has it’s own DC-DC power converter. SMA Supply is used for the ESA Cover and SST Attenuators. Note when not in use and the SST is powered there maybe a voltage present.

  9. IDPU Current Draw IMON_IDPU current monitor should indicate total current drawn on IDPU supplies – all LVPS supplies except ESA and EFI. IDPU current monitors – there is no current monitor for +8V, current is drawn from the +10V supply.

  10. IDPU Commands Listed in the thm_fsw_003_ctm.xls in the commands tab. See handout…

  11. IDPU Telemetry IDPU produces Housekeeping data only. There are three types of IDPU housekeeping packet: APID 404 – IDPU Housekeeping. APID 406 – Instrument Housekeeping. APID 407 – Memory Dump Packet.

  12. SSR ITOS Page SSR Mode – SLOW, FAST, PARTICLE BURST, WAVE BURST. Packets assigned to memory – not packets completed. When playing telemetry packet minimums prevent the play out of all packets from Engineering, Quick Look and Survey. Burst memory plays all packets.

  13. ETC The ETC takes the data from the ESA and SST instruments and formats into the distributions and moment data that are telemetered to the ground. The ETC controls the way it counts the particles by using tables that say how to bin particular particle counts from each of the instruments. These tables are stored in the IDPU EEProm and are uploaded using the 0x66?? command. Currently the version is 0x5? where ? is the table number. Table 50 is the largest and has all the tables the ETC needs to compute the moments and the default maps for SST and ESA. Note: If you load table 50 it will upload tables to both instruments! The other tables are for either ESA or SST.

  14. Compression The IDPU compresses the science data to make full use of the downlink. It is expected that the compression ratio will be about 2. If you play data while the compressor is on, you will get corrupt packets.

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