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2.1Overview
Overview
Table2-1liststhesevenkeysubmodulestogetherwithalistoftheirmainconfigurationparameters.For
example,ifyouneedtoadjustorcontrolthedutycycleofaPWMwaveform,thenyoushouldseethe
counter-comparesubmoduleinSection2.3forrelevantdetails.
Table2-1.SubmoduleConfigurationParameters
SubmoduleConfigurationParameterorOption
Time-base(TB)
•Scalethetime-baseclock(TBCLK)relativetothesystemclock(SYSCLKOUT).
•ConfigurethePWMtime-basecounter(TBCTR)frequencyorperiod.
•Setthemodeforthetime-basecounter:
–count-upmode:usedforasymmetricPWM
–count-downmode:usedforasymmetricPWM
–count-up-and-downmode:usedforsymmetricPWM
•Configurethetime-basephaserelativetoanotherePWMmodule.
•Synchronizethetime-basecounterbetweenmodulesthroughhardwareorsoftware.
•Configurethedirection(upordown)ofthetime-basecounterafterasynchronizationevent.
•Configurehowthetime-basecounterwillbehavewhenthedeviceishaltedbyanemulator.
•SpecifythesourceforthesynchronizationoutputoftheePWMmodule:
–Synchronizationinputsignal
–Time-basecounterequaltozero
–Time-basecounterequaltocounter-compareB(CMPB)
–Nooutputsynchronizationsignalgenerated.
Counter-compare(CC)
•SpecifythePWMdutycycleforoutputEPWMxAand/oroutputEPWMxB
•SpecifythetimeatwhichswitchingeventsoccurontheEPWMxAorEPWMxBoutput
Action-qualifier(AQ)
•Specifythetypeofactiontakenwhenatime-baseorcounter-comparesubmoduleeventoccurs:
–Noactiontaken
–OutputEPWMxAand/orEPWMxBswitchedhigh
–OutputEPWMxAand/orEPWMxBswitchedlow
–OutputEPWMxAand/orEPWMxBtoggled
•ForcethePWMoutputstatethroughsoftwarecontrol
•ConfigureandcontrolthePWMdead-bandthroughsoftware
Dead-band(DB)
•Controloftraditionalcomplementarydead-bandrelationshipbetweenupperandlowerswitches
•Specifytheoutputrising-edge-delayvalue
•Specifytheoutputfalling-edgedelayvalue
•Bypassthedead-bandmoduleentirely.InthiscasethePWMwaveformispassedthrough
withoutmodification.
PWM-chopper(PC)
•Createachopping(carrier)frequency.
•Pulsewidthofthefirstpulseinthechoppedpulsetrain.
•Dutycycleofthesecondandsubsequentpulses.
•BypassthePWM-choppermoduleentirely.InthiscasethePWMwaveformispassedthrough
withoutmodification.
Trip-zone(TZ)
•ConfiguretheePWMmoduletoreacttoone,all,ornoneofthetrip-zonepins.
•Specifythetrippingactiontakenwhenafaultoccurs:
–ForceEPWMxAand/orEPWMxBhigh
–ForceEPWMxAand/orEPWMxBlow
–ForceEPWMxAand/orEPWMxBtoahigh-impedancestate
–ConfigureEPWMxAand/orEPWMxBtoignoreanytripcondition.
•ConfigurehowoftentheePWMwillreacttoeachtrip-zonepin:
–One-shot
–Cycle-by-cycle
•Enablethetrip-zonetoinitiateaninterrupt.
•Bypassthetrip-zonemoduleentirely.
20ePWMSubmodulesSPRU791D–November2004–RevisedOctober2007
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