1Kurt KeutzerLecture 9: Digital Signal Processors:Applications and ArchitecturesPrepared by: Professor Kurt KeutzerComputer Science 252, Spring 2000With contributions from:Dr. Jeff Bier, BDTI; Dr. Brock Barton, TI; Prof. Bob Brodersen, Prof. David Patterson2Kurt KeutzerProcessor ApplicationsGeneral Purpose - high performance● Pentiums, Alpha’s, SPARC● Used for general purpose software ● Heavy weight OS - UNIX, NT● Workstations, PC’sEmbedded processors and processor cores● ARM, 486SX, Hitachi SH7000, NEC V800● Single program● Lightweight, often realtime OS● DSP support● Cellular phones, consumer electronics (e.g. CD players) Microcontrollers ● Extremely cost sensitive● Small word size - 8 bit common● Highest volume processors by far● Automobiles, toasters, thermostats, ... IncreasingCostIncreasingvolume3Kurt KeutzerProcessor Markets$30B$9.3B/31%$5.7B/19%$10B/33%8-bitmicro16-bitmicroDSP32-bitmicro$5.2B/17%$1.2B/4%32 bit DSP4Kurt KeutzerThe Processor Design SpaceCostPerformanceMicroprocessorsPerformance iseverything& Software rulesEmbeddedprocessorsMicrocontrollersCost is everythingApplication specific architecturesfor performance5Kurt KeutzerMarket for DSP ProductsMixed/SignalAnalogDSPDSP is the fastest growing segment of the semiconductor market6Kurt KeutzerDSP ApplicationsAudio applications• MPEG Audio• Portable audioDigital camerasWireless• Cellular telephones• Base stationNetworking• Cable modems• ADSL• VDSL7Kurt KeutzerAnother Look at DSP ApplicationsHigh-end● Wireless Base Station - TMS320C6000● Cable modem ● gatewaysMid-end● Cellular phone - TMS320C540● Fax/ voice serverLow end● Storage products - TMS320C27● Digital camera - TMS320C5000● Portable phones● Wireless headsets● Consumer audio● Automobiles, toasters, thermostats, ... IncreasingCostIncreasingvolume8Kurt KeutzerServing a range of applications9Kurt KeutzerWorld’s Cellular Subscribers01002003004005006007001993 1994 1995 1996 1997 1998 1999 2000 2001MillionsYearDigitalAnalogSource: Ericsson Radio Systems, Inc.Will providea ubiquitousinfrastructurefor wirelessdata as wellas voice10Kurt KeutzerCELLULAR TELEPHONE SYSTEMPHYSICALLAYERPROCESSINGRF MODEMCONTROLLER1 2 3 4 5 67 8 90415-555-1212SPEECHDECODESPEECHENCODEA/DBASEBANDCONVERTERDAC11Kurt KeutzerHW/SW/IC PARTITIONINGPHYSICALLAYERPROCESSINGRF MODEMCONTROLLER1 2 3 4 5 67 8 90415-555-1212SPEECHDECODESPEECHENCODEA/DBASEBANDCONVERTERDACANALOG ICDSPASICMICROCONTROLLER12Kurt KeutzerMapping onto a system on a chip RAMµCRAMDSPCOREASICLOGICS/PDMAphonebookprotocolkeypadintfccontrolS/PDMAspeechqualityenhancmentde-intl &decodervoicerecognitionRPE-LTPspeech decoderdemodulatorandsynchronizerViterbiequalizer13Kurt KeutzerExample Wireless Phone OrganizationC540ARM714Kurt KeutzerMultimedia I/O Architecture Low Power BusRadioModemEmbedded ProcessorFifoVideoDecompVideoAudioFBFifoGraphicsPenSched ECC PactInterfaceDataFlowSRAM15Kurt KeutzerMultimedia System on a ChipFuture chips will be a mix of processors, memory and dedicated hardware for specific algorithms and I/OµPDSPComsVideo UnitcustomMemoryUplink RadioDownlink RadioGraphics OutVideo I/OVoice I/OPen InE.g. Multimedia terminal electronics16Kurt KeutzerRequirements of the Embedded ProcessorsOptimized for a single program - code often in on-chip ROM or off chip EPROMMinimum code size (one of the motivations initially for Java)Performance obtained by optimizing datapathLow cost● Lowest possible area● Technology behind the leading edge● High level of integration of peripherals (reduces system cost)Fast time to market● Compatible architectures (e.g. ARM) allows reuseable code● Customizable coreLow power if application requires portability17Kurt KeutzerArea of processor cores = CostNintendo processorCellular phones18Kurt KeutzerAnother figure of meritComputation per unit areaNintendo processorCellular phones???19Kurt KeutzerCode sizeIf a majority of the chip is the program stored in ROM, then code size is a critical issueThe Piranha has 3 sized instructions - basic 2 byte, and 2 byte plus 16 or 32 bit immediate20Kurt KeutzerBENCHMARKS - DSPstoneZIVOJNOVIC, VERLADE, SCHLAGER: UNIVERSITY OF AACHENAPPLICATION BENCHMARKS● ADPCM TRANSCODER - CCITT G.721● REAL_UPDATE● COMPLEX_UPDATES● DOT_PRODUCT● MATRIX_1X3● CONVOLUTION● FIR● FIR2DIM● HR_ONE_BIQUAD● LMS● FFT_INPUT_SCALED21Kurt KeutzerEvolution of GP and DSPGeneral Purpose Microprocessor traces roots back to Eckert,Mauchly, Von Neumann (ENIAC)DSP evolved from Analog Signal Processors, using analog hardwareto transform phyical signals (classical electrical engineering)ASP to DSP because● DSP insensitive to environment (e.g., same response in snow or desert if it works at all)● DSP performance identical even with variations in components; 2 analog systems behavior varies even if built with same components with 1% variationDifferent history and different applications led to different terms, different metrics, some new inventionsConvergence of markets will lead to architectural showdown22Kurt KeutzerEmbedded Systems vs. General Purpose Computing - 1Embedded SystemRuns a few applications often known at design timeNot end-user programmableOperates in fixed run-time constraints, additional performance may not be useful/valuableGeneral purpose computingIntended to run a fully general set of applicationsEnd-user programmableFaster is always better23Kurt KeutzerEmbedded Systems vs. General Purpose Computing - 2Embedded SystemDifferentiating features:● power● cost● speed (must be predictable)General purpose computingDifferentiating features● speed (need not be fully predictable)● speed● did we mention speed?● cost (largest component power)24Kurt KeutzerDSP vs. General Purpose MPUDSPs tend to be written for 1 program, not many programs. ● Hence OSes are much simpler, there is no virtual memory or protection, ...DSPs sometimes run hard real-time apps● You must account for anything that could happen in a time slot ● All possible interrupts or exceptions must be accounted for and their collective time be subtracted from the time interval. ● Therefore, exceptions are BAD!DSPs have an infinite continuous data stream25Kurt KeutzerDSP vs. General Purpose MPUThe “MIPS/MFLOPS” of DSPs is speed of Multiply-Accumulate (MAC). ● DSP are judged by whether they can keep the multipliers busy 100% of the time.The "SPEC" of DSPs is 4 algorithms:● Inifinite Impule Response (IIR)
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