www.德州仪器.com
TMS320VC5402A
fixed-pointdigitalsignalprocessor
SPRS015E–SEPTEMBER2001–REVISEDJANUARY2005
table2-2.signaldescriptions(持续)
终端
i/o
(1)
描述
名字
微处理器/microcomputermodeselect.ifactivelowatreset,microcomputermodeisselected,和
theinternalprogramromismappedintotheupper16kwordsofprogrammemoryspace.ifthepinis
mp/mcidrivenhighduringreset,microprocessormodeisselected,andtheon-chipromisremovedfrom
programspace.thispinisonlysampledatreset,andthemp/mcbitoftheprocessormodestatus
(pmst)registercanoverridethemodethatisselectedatreset.
MULTIPROCESSINGSIGNALS
branchcontrol.abranchcanbeconditionallyexecutedwhenbioisactive.iflow,theprocessorexecutes
BIO
(1)
itheconditionalinstruction.thebioconditionissampledduringthedecodephaseofthepipelineforthe
xcinstruction,andallotherinstructionssamplebioduringthereadphaseofthepipeline.
externalflagoutput(latchedsoftware-programmablesignal).xfissethighbythessbxxfinstruction,
setlowbyrsbxxfinstructionorbyloadingst1.xfisusedforsignalingotherprocessorsin
xfo/z
multiprocessorconfigurationsorusedasageneral-purposeoutputpin.xfgoesintothehigh-阻抗
statewhenoffislow,andissethighatreset.
MEMORYCONTROLSIGNALS
数据,程序,andi/ospaceselectsignals.ds,ps,andisarealwayshighunlessdrivenlowfor
DS
communicatingtoaparticularexternalspace.activeperiodcorrespondstovalidaddressinformation.ds,
pso/z
ps,andisareplacedintothehigh-impedancestateintheholdmode;thesesignalsalsogointothe
是
高-impedancestatewhenoffislow.
memorystrobesignal.mstrbisalwayshighunlesslow-levelassertedtoindicateanexternalbus
mstrbo/zaccesstodataorprogrammemory.mstrbisplacedinthehigh-impedancestateintheholdmode;它
alsogoesintothehigh-impedancestatewhenoffislow.
dataready.readyindicatesthatanexternaldeviceispreparedforabustransactiontobecompleted.如果
thedeviceisnotready(readyislow),theprocessorwaitsonecycleandchecksreadyagain.便条
READYI
thattheprocessorperformsreadydetectionifatleasttwosoftwarewaitstatesareprogrammed.这
readysignalisnotsampleduntilthecompletionofthesoftwarewaitstates.
读/writesignal.r/windicatestransferdirectionduringcommunicationtoanexternaldevice.r/wis
normallyinthereadmode(高),unlessitisassertedlowwhenthedspperformsawriteoperation.r/w
r/wo/z
isplacedinthehigh-impedancestateintheholdmode;anditalsogoesintothehigh-impedancestate
whenoffislow.
i/ostrobesignal.iostrbisalwayshighunlesslow-levelassertedtoindicateanexternalbusaccessto
iostrbo/zani/odevice.iostrbisplacedinthehigh-impedancestateintheholdmode;italsogoesintothe
高-impedancestatewhenoffislow.
holdinput.holdisassertedtorequestcontroloftheaddress,数据,andcontrollines.当
HOLDI
acknowledgedbythe5402a,theselinesgointothehigh-impedancestate.
holdacknowledge.holdaindicatestotheexternalcircuitrythattheprocessorisinaholdstateandthat
theaddress,数据,andcontrollinesareinthehigh-impedancestate,allowingthemtobeavailabletothe
holdao/z
externalcircuitry.holdaalsogoesintothehigh-impedancestatewhenoffislow.thispinisdriven
highduringreset.
microstatecomplete.mscindicatescompletionofallsoftwarewaitstates.whentwoormoresoftware
waitstatesareenabled,themscpingoesactiveatthebeginningofthefirstsoftwarewaitstateandgoes
msco/zinactivehighatthebeginningofthelastsoftwarewaitstate.ifconnectedtothereadyinput,msc
forcesoneexternalwaitstateafterthelastinternalwaitstateiscompleted.mscalsogoesintothe
高-impedancestatewhenoffislow.
instructionacquisitionsignal.iaqisasserted(activelow)whenthereisaninstructionaddressonthe
iaqo/z
addressbusandgoesintothehigh-impedancestatewhenoffislow.
振荡器/timersignals
clockoutputsignal.clkoutcanrepresentthemachine-cyclerateofthecpudividedby1,2,3,or4as
clkouto/zconfiguredinthebank-switchingcontrolregister(bscr).followingreset,clkoutrepresentsthe
机器-cycleratedividedby4.
clockmodeselectsignals.clkmd1-clkmd3allowtheselectionandconfigurationofdifferentclock
CLKMD1
(1)
modessuchascrystal,externalclock,andpllmode.theexternalclkmd1-clkmd3pinsaresampled
CLKMD2
(1)
I
todeterminethedesiredclockgenerationmodewhilersislow.followingreset,theclockgeneration
CLKMD3
(1)
modecanbereconfiguredbywritingtotheinternalclockmoderegisterinsoftware.
时钟/oscillatorinput.iftheinternaloscillatorisnotbeingused,x2/clkinfunctionsastheclockinput.
x2/clkin
(1)
I
(thisisrevision-依赖,seesection3.10foradditionalinformation.)
outputpinfromtheinternaloscillatorforthecrystal.iftheinternaloscillatorisnotused,x1shouldbeleft
x1ounconnected.x1doesnotgointothehigh-impedancestatewhenoffislow.(thisisrevision-
依赖,seesection3.10foradditionalinformation.)
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介绍