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Internal Housekeeping Unit (IHU)
- Fabrication Responsibility:
- Lyle Johnson, WA7GXD (USA)
Chuck Green, N0ADI (USA)
Peter Gülzow, DB2OS (Germany) - Size:
- 270x200
- Average Power Dissipation:
- 1 Watt
Description
The Integrated Housekeeping Unit (IHU) is the primary control computer for the Phase 3D spacecraft. It is based on legacy designs used aboard Phase 3A, AO-10 and AO-13. The P3D IHU is based on a Sandia-processed (rad hard) CDP1802 COSMAC processor and standard 4000-series CMOS logic operating at a nominal power supply of 10-volts. The memory array is based on donated GEC Plessey MA9287 rad-hard CMOS static RAMs, giving a total memory size of 64k bytes. The memory is error-correcting, using the same algorithms that have flown on previous Phase 3 missions. In addition to the normal complement of features (digital inputs and outputs, analog-to-digital converter, timers, telemetry parallel-to-serial converters, clock oscillator, and the like), the P3D version of the IHU also incorporates a Controller Area Network (CAN) interface based on the Intel 82527 chip.The module uses through-hole technology, a 4-layer PC board and right-angle PCB mounted connectors to eliminate the internal wiring harness. It is constructed on a single 200mm X 270mm PCB and includes the command decoder. In previous missions, the command decoder, memory and CPU were on a total of three (3) PCBs using the previous standard module size of 200mm X 300mm.
The flight unit was delivered to Marburg in October, 1995. Several engineering units have also been built and are in use for flight software development and spacecraft systems checkout.
Last updated: Feb 4, 1996
by Ralf Zimmermann, DL1FDT
This URL: http://www.RalfZimmermann.de/phase3d/ihu.html