Texas Instruments TMS320x28xx Network Router User Manual


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Action-qualifier(AQ)Module
AQCTLA[15:0]
Action-qualifiercontrolA
EPWMA
EPWMB
TBCLK
CTR=PRD
CTR=Zero
CTR=CMPA
CTR=CMPB
CTR_dir
AQCTLB[15:0]
Action-qualifiercontrolB
AQSFRC[15:0]
Action-qualifierS/Wforce
AQCSFRC[3:0](shadow)
continuousS/Wforce
AQCSFRC[3:0](active)
continuousS/Wforce
Action-Qualifier(AQ)Submodule
Theaction-qualifiersubmoduleisbasedonevent-drivenlogic.Itcanbethoughtofasaprogrammable
crossswitchwitheventsattheinputandactionsattheoutput,allofwhicharesoftwarecontrolledviathe
setofregistersshowninTable2-6.
Figure2-18.Action-QualifierSubmoduleInputsandOutputs
Forconvenience,thepossibleinputeventsaresummarizedagaininTable2-7.
Table2-7.Action-QualifierSubmodulePossibleInputEvents
SignalDescriptionRegistersCompared
CTR=PRDTime-basecounterequaltotheperiodvalueTBCTR=TBPRD
CTR=ZeroTime-basecounterequaltozeroTBCTR=0x0000
CTR=CMPATime-basecounterequaltothecounter-compareATBCTR=CMPA
CTR=CMPBTime-basecounterequaltothecounter-compareBTBCTR=CMPB
SoftwareforcedeventAsynchronouseventinitiatedbysoftware
Thesoftwareforcedactionisausefulasynchronousevent.ThiscontrolishandledbyregistersAQSFRC
andAQCSFRC.
Theaction-qualifiersubmodulecontrolshowthetwooutputsEPWMxAandEPWMxBbehavewhena
particulareventoccurs.Theeventinputstotheaction-qualifiersubmodulearefurtherqualifiedbythe
counterdirection(upordown).Thisallowsforindependentactiononoutputsonboththecount-upand
count-downphases.
ThepossibleactionsimposedonoutputsEPWMxAandEPWMxBare:
•SetHigh:
SetoutputEPWMxAorEPWMxBtoahighlevel.
•ClearLow:
SetoutputEPWMxAorEPWMxBtoalowlevel.
•Toggle:
IfEPWMxAorEPWMxBiscurrentlypulledhigh,thenpulltheoutputlow.IfEPWMxAorEPWMxBis
currentlypulledlow,thenpulltheoutputhigh.
•DoNothing:
KeepoutputsEPWMxAandEPWMxBatsamelevelascurrentlyset.Althoughthe"DoNothing"option
preventsaneventfromcausinganactionontheEPWMxAandEPWMxBoutputs,thiseventcanstill
triggerinterruptsandADCstartofconversion.SeetheEvent-triggerSubmoduledescriptionin
Section2.8fordetails.
38ePWMSubmodulesSPRU791D–November2004–RevisedOctober2007
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