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3.2.10peripheralinterruptexpansion(pie)块
3.2.11externalinterrupts(xint1,xint2,xnmi)
3.2.12oscillatorandpll
3.2.13watchdog
3.2.14peripheralclocking
3.2.15low-powermodes
tms320f2808,tms320f2806
tms320f2801,ucd9501
DigitalSignalProcessors
SPRS230F–OCTOBER2003–REVISEDSEPTEMBER2005
thepieblockservestomultiplexnumerousinterruptsourcesintoasmallersetofinterruptinputs.这
pieblockcansupportupto96peripheralinterrupts.onthe280x,43ofthepossible96interruptsare
usedbyperipherals.the96interruptsaregroupedintoblocksof8andeachgroupisfedinto1of12
cpuinterruptlines(int1toint12).eachofthe96interruptsissupportedbyitsownvectorstoredina
dedicatedramblockthatcanbeoverwrittenbytheuser.thevectorisautomaticallyfetchedbythecpu
onservicingtheinterrupt.ittakes8cpuclockcyclestofetchthevectorandsavecriticalcpuregisters.
hencethecpucanquicklyrespondtointerruptevents.prioritizationofinterruptsiscontrolledin
hardwareandsoftware.eachindividualinterruptcanbeenabled/disabledwithinthepieblock.
the280xsupportsthreemaskedexternalinterrupts(xint1,xint2,xnmi).xnmicanbeconnectedto
theint13ornmiinterruptofthecpu.eachoftheinterruptscanbeselectedfornegative,积极的,或者
bothnegativeandpositiveedgetriggeringandcanalsobeenabled/无能(includingthexnmi).这
maskedinterruptsalsocontaina16-bitfreerunningupcounter,whichisresettozerowhenavalid
interruptedgeisdetected.thiscountercanbeusedtoaccuratelytimestamptheinterrupt.unlikethe
281xdevices,therearenodedicatedpinsfortheexternalinterrupts.相当,anyportagpiopincanbe
configuredtotriggeranyexternalinterrupt.
the280xcanbeclockedbyanexternaloscillatororbyacrystalattachedtotheon-chiposcillatorcircuit.
apllisprovidedsupportingupto10input-时钟-scalingratios.thepllratioscanbechangedon-这-fly
insoftware,enablingtheusertoscalebackonoperatingfrequencyiflowerpoweroperationisdesired.
refertotheelectricalspecificationsectionfortimingdetails.thepllblockcanbesetinbypassmode.
the280xdevicescontainawatchdogtimer.theusersoftwaremustregularlyresetthewatchdogcounter
withinacertaintimeframe;否则,thewatchdogwillgeneratearesettotheprocessor.thewatchdog
canbedisabledifnecessary.
theclockstoeachindividualperipheralcanbeenabled/disabledsoastoreducepowerconsumption
whenaperipheralisnotinuse.additionally,thesystemclocktotheserialports(exceptecan)andthe
adcblockscanbescaledrelativetothecpuclock.thisenablesthetimingofperipheralstobe
decoupledfromincreasingcpuclockspeeds.
the280xdevicesarefullstaticcmosdevices.threelow-powermodesareprovided:
空闲:placecpuintolow-powermode.peripheralclocksmaybeturnedoffselectivelyandonly
thoseperipheralsthatneedtofunctionduringidleareleftoperating.anenabledinterrupt
fromanactiveperipheralorthewatchdogtimerwillwaketheprocessorfromidlemode.
备用物品:turnoffclocktocpuandperipherals.thismodeleavestheoscillatorandpllfunctional.
anexternalinterrupteventwillwaketheprocessorandtheperipherals.executionbegins
onthenextvalidcycleafterdetectionoftheinterruptevent
halt:turnoffoscillator.thismodebasicallyshutsdownthedeviceandplacesitinthelowest
possiblepowerconsumptionmode.aresetorexternalsignalcanwakethedevicefrom
thismode.
FunctionalOverview
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