DCH RequirementsDCH Requirements

Process at a rate fast enough to maintain all Process at a rate fast enough to maintain all data storage and command handling tasks.data storage and command handling tasks.

Have sufficient storage space to hold the OS, Have sufficient storage space to hold the OS, science data, and other command handling science data, and other command handling softwaresoftware

Must detect, verify and distribute all commandsMust detect, verify and distribute all commands Must withstand a total dose radiation of up to Must withstand a total dose radiation of up to

15Krads15Krads Must be able to recover from single event upset Must be able to recover from single event upset

errors/ hard bit errorserrors/ hard bit errors

DCH Requirements, cont.DCH Requirements, cont.

Maximum Power consumption of 12 Maximum Power consumption of 12 watts(transient) and 7 watts (steady state)watts(transient) and 7 watts (steady state)

Maximum Volume goal of 7500 cc’sMaximum Volume goal of 7500 cc’s Must provide internal housekeeping functions Must provide internal housekeeping functions

for all other satellite subsystems and for all other satellite subsystems and instruments.instruments.

Selecting ProcessorSelecting Processor

Need a low power embedded processor Need a low power embedded processor Need a processor that withstands a radiation environment Need a processor that withstands a radiation environment

( to within certain tolerances)( to within certain tolerances) Processor must be able to recover from single event Processor must be able to recover from single event

upsetsupsets Need a processor with various power consumption modesNeed a processor with various power consumption modes Need to have DMA, so that subsystems can write to and Need to have DMA, so that subsystems can write to and

read from memory without effecting the CPU’s read from memory without effecting the CPU’s performance.performance.

About the Intel 386EX About the Intel 386EX ProcessorProcessor

Contains a modular, fully static 386CX CPU Contains a modular, fully static 386CX CPU 16 bit data bus and 26 bit address bus16 bit data bus and 26 bit address bus 64Mbytes of memory address space64Mbytes of memory address space 64Kbytes of I/O address space64Kbytes of I/O address space Available in three clock rates (16, 25, 33 MHz)Available in three clock rates (16, 25, 33 MHz) Watchdog timerWatchdog timer Idle mode and Powerdown mode to conserve powerIdle mode and Powerdown mode to conserve power

More about the 386EXMore about the 386EX

Normal operation power consumption is Normal operation power consumption is 1.125-1.76 Watts (depends on Clock 1.125-1.76 Watts (depends on Clock speed)speed)

University of Surrey and Honeywell University of Surrey and Honeywell have radiation tested this processor.have radiation tested this processor.

Software and Data Software and Data StorageStorage

OS and any other command handling software will be OS and any other command handling software will be stored on an EPROMstored on an EPROM

Data from Science Team will be buffered while satellite Data from Science Team will be buffered while satellite is out of contact with the radio groundstationis out of contact with the radio groundstation• The data will be saved to Static RAM and then sent to the The data will be saved to Static RAM and then sent to the

groundstation. groundstation.

OS considerationsOS considerations

Need a protected mode kernalNeed a protected mode kernal Need a multitasking, real time OSNeed a multitasking, real time OS Types of operating systems we have considered buyingTypes of operating systems we have considered buying

• DR-DOS - by CalderaDR-DOS - by Caldera• eCos - by CygnuseCos - by Cygnus• iRMXII - by RadisysiRMXII - by Radisys

System I/O ConcernsSystem I/O Concerns Guidance, Navigation and ControlGuidance, Navigation and Control

• magnetonmeter - measure magnetic fieldsmagnetonmeter - measure magnetic fields• sun sensors- Frequency Countersun sensors- Frequency Counter• horizon sensors - Analog Inputhorizon sensors - Analog Input

Power Generation and DistributionPower Generation and Distribution• monitor power systems -Analog inputmonitor power systems -Analog input

Mechanical and Structural AnalysisMechanical and Structural Analysis• monitor thermal - Analog inputmonitor thermal - Analog input

Laser ExperimentLaser Experiment• experimental uplink communicating at 10Mbit/sexperimental uplink communicating at 10Mbit/s

Tracking, Telemetry and CommandTracking, Telemetry and Command• communication with groundstationcommunication with groundstation

– 2Mbit/s downlink2Mbit/s downlink– 9600 bit/s uplink 9600 bit/s uplink

ScienceScience• buffering science databuffering science data• data compressiondata compression

Systems I/O Concerns, Systems I/O Concerns, cont.cont.

DCH Block Diagram

Opportunities with UASatOpportunities with UASat

We need Electrical Engineers, Computer We need Electrical Engineers, Computer Engineers, and Computer Science Engineers, and Computer Science majors. majors.

Consists of one meeting a week and any Consists of one meeting a week and any assignments designated by team leaderassignments designated by team leader

We have a full version of Layout Plus We have a full version of Layout Plus and Capture(the new PSPICE products)and Capture(the new PSPICE products)

Programmers will gain embedded Programmers will gain embedded systems software experience. systems software experience.